diff options
Diffstat (limited to 'pkg/sentry/fsimpl')
77 files changed, 6324 insertions, 622 deletions
diff --git a/pkg/sentry/fsimpl/devpts/BUILD b/pkg/sentry/fsimpl/devpts/BUILD index 585764223..93512c9b6 100644 --- a/pkg/sentry/fsimpl/devpts/BUILD +++ b/pkg/sentry/fsimpl/devpts/BUILD @@ -18,6 +18,7 @@ go_library( "//pkg/context", "//pkg/safemem", "//pkg/sentry/arch", + "//pkg/sentry/fs/lock", "//pkg/sentry/fsimpl/kernfs", "//pkg/sentry/kernel", "//pkg/sentry/kernel/auth", diff --git a/pkg/sentry/fsimpl/devpts/devpts.go b/pkg/sentry/fsimpl/devpts/devpts.go index c03c65445..e6fda2b4f 100644 --- a/pkg/sentry/fsimpl/devpts/devpts.go +++ b/pkg/sentry/fsimpl/devpts/devpts.go @@ -116,6 +116,8 @@ type rootInode struct { kernfs.InodeNotSymlink kernfs.OrderedChildren + locks vfs.FileLocks + // Keep a reference to this inode's dentry. dentry kernfs.Dentry @@ -183,7 +185,7 @@ func (i *rootInode) masterClose(t *Terminal) { // Open implements kernfs.Inode.Open. func (i *rootInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) if err != nil { return nil, err } diff --git a/pkg/sentry/fsimpl/devpts/master.go b/pkg/sentry/fsimpl/devpts/master.go index 7a7ce5d81..1081fff52 100644 --- a/pkg/sentry/fsimpl/devpts/master.go +++ b/pkg/sentry/fsimpl/devpts/master.go @@ -18,6 +18,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/unimpl" @@ -34,6 +35,8 @@ type masterInode struct { kernfs.InodeNotDirectory kernfs.InodeNotSymlink + locks vfs.FileLocks + // Keep a reference to this inode's dentry. dentry kernfs.Dentry @@ -55,6 +58,7 @@ func (mi *masterInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vf inode: mi, t: t, } + fd.LockFD.Init(&mi.locks) if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil { mi.DecRef() return nil, err @@ -63,8 +67,8 @@ func (mi *masterInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vf } // Stat implements kernfs.Inode.Stat. -func (mi *masterInode) Stat(vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { - statx, err := mi.InodeAttrs.Stat(vfsfs, opts) +func (mi *masterInode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { + statx, err := mi.InodeAttrs.Stat(ctx, vfsfs, opts) if err != nil { return linux.Statx{}, err } @@ -85,6 +89,7 @@ func (mi *masterInode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds type masterFileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl + vfs.LockFD inode *masterInode t *Terminal @@ -181,7 +186,17 @@ func (mfd *masterFileDescription) SetStat(ctx context.Context, opts vfs.SetStatO // Stat implements vfs.FileDescriptionImpl.Stat. func (mfd *masterFileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { fs := mfd.vfsfd.VirtualDentry().Mount().Filesystem() - return mfd.inode.Stat(fs, opts) + return mfd.inode.Stat(ctx, fs, opts) +} + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (mfd *masterFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return mfd.Locks().LockPOSIX(ctx, &mfd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (mfd *masterFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return mfd.Locks().UnlockPOSIX(ctx, &mfd.vfsfd, uid, start, length, whence) } // maybeEmitUnimplementedEvent emits unimplemented event if cmd is valid. diff --git a/pkg/sentry/fsimpl/devpts/slave.go b/pkg/sentry/fsimpl/devpts/slave.go index 526cd406c..a91cae3ef 100644 --- a/pkg/sentry/fsimpl/devpts/slave.go +++ b/pkg/sentry/fsimpl/devpts/slave.go @@ -18,6 +18,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/vfs" @@ -33,6 +34,8 @@ type slaveInode struct { kernfs.InodeNotDirectory kernfs.InodeNotSymlink + locks vfs.FileLocks + // Keep a reference to this inode's dentry. dentry kernfs.Dentry @@ -51,6 +54,7 @@ func (si *slaveInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs fd := &slaveFileDescription{ inode: si, } + fd.LockFD.Init(&si.locks) if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil { si.DecRef() return nil, err @@ -69,8 +73,8 @@ func (si *slaveInode) Valid(context.Context) bool { } // Stat implements kernfs.Inode.Stat. -func (si *slaveInode) Stat(vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { - statx, err := si.InodeAttrs.Stat(vfsfs, opts) +func (si *slaveInode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { + statx, err := si.InodeAttrs.Stat(ctx, vfsfs, opts) if err != nil { return linux.Statx{}, err } @@ -91,6 +95,7 @@ func (si *slaveInode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds type slaveFileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl + vfs.LockFD inode *slaveInode } @@ -127,7 +132,7 @@ func (sfd *slaveFileDescription) Write(ctx context.Context, src usermem.IOSequen return sfd.inode.t.ld.outputQueueWrite(ctx, src) } -// Ioctl implements vfs.FileDescripionImpl.Ioctl. +// Ioctl implements vfs.FileDescriptionImpl.Ioctl. func (sfd *slaveFileDescription) Ioctl(ctx context.Context, io usermem.IO, args arch.SyscallArguments) (uintptr, error) { switch cmd := args[1].Uint(); cmd { case linux.FIONREAD: // linux.FIONREAD == linux.TIOCINQ @@ -178,5 +183,15 @@ func (sfd *slaveFileDescription) SetStat(ctx context.Context, opts vfs.SetStatOp // Stat implements vfs.FileDescriptionImpl.Stat. func (sfd *slaveFileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { fs := sfd.vfsfd.VirtualDentry().Mount().Filesystem() - return sfd.inode.Stat(fs, opts) + return sfd.inode.Stat(ctx, fs, opts) +} + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (sfd *slaveFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return sfd.Locks().LockPOSIX(ctx, &sfd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (sfd *slaveFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return sfd.Locks().UnlockPOSIX(ctx, &sfd.vfsfd, uid, start, length, whence) } diff --git a/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go b/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go index 142ee53b0..d0e06cdc0 100644 --- a/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go +++ b/pkg/sentry/fsimpl/devtmpfs/devtmpfs.go @@ -136,6 +136,8 @@ func (a *Accessor) pathOperationAt(pathname string) *vfs.PathOperation { // CreateDeviceFile creates a device special file at the given pathname in the // devtmpfs instance accessed by the Accessor. func (a *Accessor) CreateDeviceFile(ctx context.Context, pathname string, kind vfs.DeviceKind, major, minor uint32, perms uint16) error { + actx := a.wrapContext(ctx) + mode := (linux.FileMode)(perms) switch kind { case vfs.BlockDevice: @@ -145,12 +147,24 @@ func (a *Accessor) CreateDeviceFile(ctx context.Context, pathname string, kind v default: panic(fmt.Sprintf("invalid vfs.DeviceKind: %v", kind)) } + + // Create any parent directories. See + // devtmpfs.c:handle_create()=>path_create(). + for it := fspath.Parse(pathname).Begin; it.NextOk(); it = it.Next() { + pop := a.pathOperationAt(it.String()) + if err := a.vfsObj.MkdirAt(actx, a.creds, pop, &vfs.MkdirOptions{ + Mode: 0755, + }); err != nil { + return fmt.Errorf("failed to create directory %q: %v", it.String(), err) + } + } + // NOTE: Linux's devtmpfs refuses to automatically delete files it didn't // create, which it recognizes by storing a pointer to the kdevtmpfs struct // thread in struct inode::i_private. Accessor doesn't yet support deletion // of files at all, and probably won't as long as we don't need to support // kernel modules, so this is moot for now. - return a.vfsObj.MknodAt(a.wrapContext(ctx), a.creds, a.pathOperationAt(pathname), &vfs.MknodOptions{ + return a.vfsObj.MknodAt(actx, a.creds, a.pathOperationAt(pathname), &vfs.MknodOptions{ Mode: mode, DevMajor: major, DevMinor: minor, diff --git a/pkg/sentry/fsimpl/eventfd/eventfd.go b/pkg/sentry/fsimpl/eventfd/eventfd.go index c573d7935..d12d78b84 100644 --- a/pkg/sentry/fsimpl/eventfd/eventfd.go +++ b/pkg/sentry/fsimpl/eventfd/eventfd.go @@ -37,6 +37,7 @@ type EventFileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl vfs.DentryMetadataFileDescriptionImpl + vfs.NoLockFD // queue is used to notify interested parties when the event object // becomes readable or writable. diff --git a/pkg/sentry/fsimpl/ext/BUILD b/pkg/sentry/fsimpl/ext/BUILD index ff861d0fe..abc610ef3 100644 --- a/pkg/sentry/fsimpl/ext/BUILD +++ b/pkg/sentry/fsimpl/ext/BUILD @@ -54,6 +54,7 @@ go_library( "//pkg/safemem", "//pkg/sentry/arch", "//pkg/sentry/fs", + "//pkg/sentry/fs/lock", "//pkg/sentry/fsimpl/ext/disklayout", "//pkg/sentry/kernel/auth", "//pkg/sentry/memmap", @@ -95,7 +96,7 @@ go_test( "//pkg/syserror", "//pkg/test/testutil", "//pkg/usermem", - "@com_github_google_go-cmp//cmp:go_default_library", - "@com_github_google_go-cmp//cmp/cmpopts:go_default_library", + "@com_github_google_go_cmp//cmp:go_default_library", + "@com_github_google_go_cmp//cmp/cmpopts:go_default_library", ], ) diff --git a/pkg/sentry/fsimpl/ext/block_map_file.go b/pkg/sentry/fsimpl/ext/block_map_file.go index a2d8c3ad6..8bb104ff0 100644 --- a/pkg/sentry/fsimpl/ext/block_map_file.go +++ b/pkg/sentry/fsimpl/ext/block_map_file.go @@ -58,15 +58,16 @@ var _ io.ReaderAt = (*blockMapFile)(nil) // newBlockMapFile is the blockMapFile constructor. It initializes the file to // physical blocks map with (at most) the first 12 (direct) blocks. -func newBlockMapFile(regFile regularFile) (*blockMapFile, error) { - file := &blockMapFile{regFile: regFile} +func newBlockMapFile(args inodeArgs) (*blockMapFile, error) { + file := &blockMapFile{} file.regFile.impl = file + file.regFile.inode.init(args, &file.regFile) for i := uint(0); i < 4; i++ { - file.coverage[i] = getCoverage(regFile.inode.blkSize, i) + file.coverage[i] = getCoverage(file.regFile.inode.blkSize, i) } - blkMap := regFile.inode.diskInode.Data() + blkMap := file.regFile.inode.diskInode.Data() binary.Unmarshal(blkMap[:numDirectBlks*4], binary.LittleEndian, &file.directBlks) binary.Unmarshal(blkMap[numDirectBlks*4:(numDirectBlks+1)*4], binary.LittleEndian, &file.indirectBlk) binary.Unmarshal(blkMap[(numDirectBlks+1)*4:(numDirectBlks+2)*4], binary.LittleEndian, &file.doubleIndirectBlk) diff --git a/pkg/sentry/fsimpl/ext/block_map_test.go b/pkg/sentry/fsimpl/ext/block_map_test.go index 181727ef7..6fa84e7aa 100644 --- a/pkg/sentry/fsimpl/ext/block_map_test.go +++ b/pkg/sentry/fsimpl/ext/block_map_test.go @@ -85,20 +85,6 @@ func (n *blkNumGen) next() uint32 { // the inode covers and that is written to disk. func blockMapSetUp(t *testing.T) (*blockMapFile, []byte) { mockDisk := make([]byte, mockBMDiskSize) - regFile := regularFile{ - inode: inode{ - fs: &filesystem{ - dev: bytes.NewReader(mockDisk), - }, - diskInode: &disklayout.InodeNew{ - InodeOld: disklayout.InodeOld{ - SizeLo: getMockBMFileFize(), - }, - }, - blkSize: uint64(mockBMBlkSize), - }, - } - var fileData []byte blkNums := newBlkNumGen() var data []byte @@ -125,9 +111,20 @@ func blockMapSetUp(t *testing.T) (*blockMapFile, []byte) { data = binary.Marshal(data, binary.LittleEndian, triplyIndirectBlk) fileData = append(fileData, writeFileDataToBlock(mockDisk, triplyIndirectBlk, 3, blkNums)...) - copy(regFile.inode.diskInode.Data(), data) + args := inodeArgs{ + fs: &filesystem{ + dev: bytes.NewReader(mockDisk), + }, + diskInode: &disklayout.InodeNew{ + InodeOld: disklayout.InodeOld{ + SizeLo: getMockBMFileFize(), + }, + }, + blkSize: uint64(mockBMBlkSize), + } + copy(args.diskInode.Data(), data) - mockFile, err := newBlockMapFile(regFile) + mockFile, err := newBlockMapFile(args) if err != nil { t.Fatalf("newBlockMapFile failed: %v", err) } diff --git a/pkg/sentry/fsimpl/ext/dentry.go b/pkg/sentry/fsimpl/ext/dentry.go index bfbd7c3d4..55902322a 100644 --- a/pkg/sentry/fsimpl/ext/dentry.go +++ b/pkg/sentry/fsimpl/ext/dentry.go @@ -60,3 +60,20 @@ func (d *dentry) DecRef() { // inode.decRef(). d.inode.decRef() } + +// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. +// +// TODO(b/134676337): Implement inotify. +func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {} + +// Watches implements vfs.DentryImpl.Watches. +// +// TODO(b/134676337): Implement inotify. +func (d *dentry) Watches() *vfs.Watches { + return nil +} + +// OnZeroWatches implements vfs.Dentry.OnZeroWatches. +// +// TODO(b/134676337): Implement inotify. +func (d *dentry) OnZeroWatches() {} diff --git a/pkg/sentry/fsimpl/ext/directory.go b/pkg/sentry/fsimpl/ext/directory.go index 12b875c8f..357512c7e 100644 --- a/pkg/sentry/fsimpl/ext/directory.go +++ b/pkg/sentry/fsimpl/ext/directory.go @@ -20,6 +20,7 @@ import ( "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/sentry/fs" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/fsimpl/ext/disklayout" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/sync" @@ -54,16 +55,15 @@ type directory struct { } // newDirectory is the directory constructor. -func newDirectory(inode inode, newDirent bool) (*directory, error) { +func newDirectory(args inodeArgs, newDirent bool) (*directory, error) { file := &directory{ - inode: inode, childCache: make(map[string]*dentry), childMap: make(map[string]*dirent), } - file.inode.impl = file + file.inode.init(args, file) // Initialize childList by reading dirents from the underlying file. - if inode.diskInode.Flags().Index { + if args.diskInode.Flags().Index { // TODO(b/134676337): Support hash tree directories. Currently only the '.' // and '..' entries are read in. @@ -74,7 +74,7 @@ func newDirectory(inode inode, newDirent bool) (*directory, error) { // The dirents are organized in a linear array in the file data. // Extract the file data and decode the dirents. - regFile, err := newRegularFile(inode) + regFile, err := newRegularFile(args) if err != nil { return nil, err } @@ -82,7 +82,7 @@ func newDirectory(inode inode, newDirent bool) (*directory, error) { // buf is used as scratch space for reading in dirents from disk and // unmarshalling them into dirent structs. buf := make([]byte, disklayout.DirentSize) - size := inode.diskInode.Size() + size := args.diskInode.Size() for off, inc := uint64(0), uint64(0); off < size; off += inc { toRead := size - off if toRead > disklayout.DirentSize { @@ -306,3 +306,13 @@ func (fd *directoryFD) Seek(ctx context.Context, offset int64, whence int32) (in fd.off = offset return offset, nil } + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *directoryFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *directoryFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/ext/extent_file.go b/pkg/sentry/fsimpl/ext/extent_file.go index 11dcc0346..c36225a7c 100644 --- a/pkg/sentry/fsimpl/ext/extent_file.go +++ b/pkg/sentry/fsimpl/ext/extent_file.go @@ -38,9 +38,10 @@ var _ io.ReaderAt = (*extentFile)(nil) // newExtentFile is the extent file constructor. It reads the entire extent // tree into memory. // TODO(b/134676337): Build extent tree on demand to reduce memory usage. -func newExtentFile(regFile regularFile) (*extentFile, error) { - file := &extentFile{regFile: regFile} +func newExtentFile(args inodeArgs) (*extentFile, error) { + file := &extentFile{} file.regFile.impl = file + file.regFile.inode.init(args, &file.regFile) err := file.buildExtTree() if err != nil { return nil, err diff --git a/pkg/sentry/fsimpl/ext/extent_test.go b/pkg/sentry/fsimpl/ext/extent_test.go index a2382daa3..cd10d46ee 100644 --- a/pkg/sentry/fsimpl/ext/extent_test.go +++ b/pkg/sentry/fsimpl/ext/extent_test.go @@ -177,21 +177,19 @@ func extentTreeSetUp(t *testing.T, root *disklayout.ExtentNode) (*extentFile, [] t.Helper() mockDisk := make([]byte, mockExtentBlkSize*10) - mockExtentFile := &extentFile{ - regFile: regularFile{ - inode: inode{ - fs: &filesystem{ - dev: bytes.NewReader(mockDisk), - }, - diskInode: &disklayout.InodeNew{ - InodeOld: disklayout.InodeOld{ - SizeLo: uint32(mockExtentBlkSize) * getNumPhyBlks(root), - }, - }, - blkSize: mockExtentBlkSize, + mockExtentFile := &extentFile{} + args := inodeArgs{ + fs: &filesystem{ + dev: bytes.NewReader(mockDisk), + }, + diskInode: &disklayout.InodeNew{ + InodeOld: disklayout.InodeOld{ + SizeLo: uint32(mockExtentBlkSize) * getNumPhyBlks(root), }, }, + blkSize: mockExtentBlkSize, } + mockExtentFile.regFile.inode.init(args, &mockExtentFile.regFile) fileData := writeTree(&mockExtentFile.regFile.inode, mockDisk, node0, mockExtentBlkSize) diff --git a/pkg/sentry/fsimpl/ext/file_description.go b/pkg/sentry/fsimpl/ext/file_description.go index 92f7da40d..90b086468 100644 --- a/pkg/sentry/fsimpl/ext/file_description.go +++ b/pkg/sentry/fsimpl/ext/file_description.go @@ -26,6 +26,7 @@ import ( type fileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl + vfs.LockFD } func (fd *fileDescription) filesystem() *filesystem { diff --git a/pkg/sentry/fsimpl/ext/inode.go b/pkg/sentry/fsimpl/ext/inode.go index 485f86f4b..30636cf66 100644 --- a/pkg/sentry/fsimpl/ext/inode.go +++ b/pkg/sentry/fsimpl/ext/inode.go @@ -54,6 +54,8 @@ type inode struct { // diskInode gives us access to the inode struct on disk. Immutable. diskInode disklayout.Inode + locks vfs.FileLocks + // This is immutable. The first field of the implementations must have inode // as the first field to ensure temporality. impl interface{} @@ -115,7 +117,7 @@ func newInode(fs *filesystem, inodeNum uint32) (*inode, error) { } // Build the inode based on its type. - inode := inode{ + args := inodeArgs{ fs: fs, inodeNum: inodeNum, blkSize: blkSize, @@ -124,19 +126,19 @@ func newInode(fs *filesystem, inodeNum uint32) (*inode, error) { switch diskInode.Mode().FileType() { case linux.ModeSymlink: - f, err := newSymlink(inode) + f, err := newSymlink(args) if err != nil { return nil, err } return &f.inode, nil case linux.ModeRegular: - f, err := newRegularFile(inode) + f, err := newRegularFile(args) if err != nil { return nil, err } return &f.inode, nil case linux.ModeDirectory: - f, err := newDirectory(inode, fs.sb.IncompatibleFeatures().DirentFileType) + f, err := newDirectory(args, fs.sb.IncompatibleFeatures().DirentFileType) if err != nil { return nil, err } @@ -147,6 +149,21 @@ func newInode(fs *filesystem, inodeNum uint32) (*inode, error) { } } +type inodeArgs struct { + fs *filesystem + inodeNum uint32 + blkSize uint64 + diskInode disklayout.Inode +} + +func (in *inode) init(args inodeArgs, impl interface{}) { + in.fs = args.fs + in.inodeNum = args.inodeNum + in.blkSize = args.blkSize + in.diskInode = args.diskInode + in.impl = impl +} + // open creates and returns a file description for the dentry passed in. func (in *inode) open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts *vfs.OpenOptions) (*vfs.FileDescription, error) { ats := vfs.AccessTypesForOpenFlags(opts) @@ -157,6 +174,7 @@ func (in *inode) open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts *vfs.OpenOpt switch in.impl.(type) { case *regularFile: var fd regularFileFD + fd.LockFD.Init(&in.locks) if err := fd.vfsfd.Init(&fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } @@ -168,6 +186,7 @@ func (in *inode) open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts *vfs.OpenOpt return nil, syserror.EISDIR } var fd directoryFD + fd.LockFD.Init(&in.locks) if err := fd.vfsfd.Init(&fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } @@ -178,6 +197,7 @@ func (in *inode) open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts *vfs.OpenOpt return nil, syserror.ELOOP } var fd symlinkFD + fd.LockFD.Init(&in.locks) fd.vfsfd.Init(&fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{}) return &fd.vfsfd, nil default: diff --git a/pkg/sentry/fsimpl/ext/regular_file.go b/pkg/sentry/fsimpl/ext/regular_file.go index 30135ddb0..66d14bb95 100644 --- a/pkg/sentry/fsimpl/ext/regular_file.go +++ b/pkg/sentry/fsimpl/ext/regular_file.go @@ -20,6 +20,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/safemem" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/sync" @@ -43,28 +44,19 @@ type regularFile struct { // newRegularFile is the regularFile constructor. It figures out what kind of // file this is and initializes the fileReader. -func newRegularFile(inode inode) (*regularFile, error) { - regFile := regularFile{ - inode: inode, - } - - inodeFlags := inode.diskInode.Flags() - - if inodeFlags.Extents { - file, err := newExtentFile(regFile) +func newRegularFile(args inodeArgs) (*regularFile, error) { + if args.diskInode.Flags().Extents { + file, err := newExtentFile(args) if err != nil { return nil, err } - - file.regFile.inode.impl = &file.regFile return &file.regFile, nil } - file, err := newBlockMapFile(regFile) + file, err := newBlockMapFile(args) if err != nil { return nil, err } - file.regFile.inode.impl = &file.regFile return &file.regFile, nil } @@ -77,6 +69,7 @@ func (in *inode) isRegular() bool { // vfs.FileDescriptionImpl. type regularFileFD struct { fileDescription + vfs.LockFD // off is the file offset. off is accessed using atomic memory operations. off int64 @@ -157,3 +150,13 @@ func (fd *regularFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpt // TODO(b/134676337): Implement mmap(2). return syserror.ENODEV } + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *regularFileFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *regularFileFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/ext/symlink.go b/pkg/sentry/fsimpl/ext/symlink.go index 1447a4dc1..62efd4095 100644 --- a/pkg/sentry/fsimpl/ext/symlink.go +++ b/pkg/sentry/fsimpl/ext/symlink.go @@ -30,18 +30,17 @@ type symlink struct { // newSymlink is the symlink constructor. It reads out the symlink target from // the inode (however it might have been stored). -func newSymlink(inode inode) (*symlink, error) { - var file *symlink +func newSymlink(args inodeArgs) (*symlink, error) { var link []byte // If the symlink target is lesser than 60 bytes, its stores in inode.Data(). // Otherwise either extents or block maps will be used to store the link. - size := inode.diskInode.Size() + size := args.diskInode.Size() if size < 60 { - link = inode.diskInode.Data()[:size] + link = args.diskInode.Data()[:size] } else { // Create a regular file out of this inode and read out the target. - regFile, err := newRegularFile(inode) + regFile, err := newRegularFile(args) if err != nil { return nil, err } @@ -52,8 +51,8 @@ func newSymlink(inode inode) (*symlink, error) { } } - file = &symlink{inode: inode, target: string(link)} - file.inode.impl = file + file := &symlink{target: string(link)} + file.inode.init(args, file) return file, nil } @@ -67,6 +66,7 @@ func (in *inode) isSymlink() bool { // O_PATH. For this reason most of the functions return EBADF. type symlinkFD struct { fileDescription + vfs.NoLockFD } // Compiles only if symlinkFD implements vfs.FileDescriptionImpl. diff --git a/pkg/sentry/fsimpl/fuse/BUILD b/pkg/sentry/fsimpl/fuse/BUILD new file mode 100644 index 000000000..999111deb --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/BUILD @@ -0,0 +1,63 @@ +load("//tools:defs.bzl", "go_library", "go_test") +load("//tools/go_generics:defs.bzl", "go_template_instance") + +licenses(["notice"]) + +go_template_instance( + name = "request_list", + out = "request_list.go", + package = "fuse", + prefix = "request", + template = "//pkg/ilist:generic_list", + types = { + "Element": "*Request", + "Linker": "*Request", + }, +) + +go_library( + name = "fuse", + srcs = [ + "connection.go", + "dev.go", + "fusefs.go", + "init.go", + "register.go", + "request_list.go", + ], + visibility = ["//pkg/sentry:internal"], + deps = [ + "//pkg/abi/linux", + "//pkg/context", + "//pkg/log", + "//pkg/sentry/fsimpl/devtmpfs", + "//pkg/sentry/fsimpl/kernfs", + "//pkg/sentry/kernel", + "//pkg/sentry/kernel/auth", + "//pkg/sentry/vfs", + "//pkg/sync", + "//pkg/syserror", + "//pkg/usermem", + "//pkg/waiter", + "//tools/go_marshal/marshal", + "@org_golang_x_sys//unix:go_default_library", + ], +) + +go_test( + name = "fuse_test", + size = "small", + srcs = ["dev_test.go"], + library = ":fuse", + deps = [ + "//pkg/abi/linux", + "//pkg/sentry/fsimpl/testutil", + "//pkg/sentry/kernel", + "//pkg/sentry/kernel/auth", + "//pkg/sentry/vfs", + "//pkg/syserror", + "//pkg/usermem", + "//pkg/waiter", + "//tools/go_marshal/marshal", + ], +) diff --git a/pkg/sentry/fsimpl/fuse/connection.go b/pkg/sentry/fsimpl/fuse/connection.go new file mode 100644 index 000000000..6df2728ab --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/connection.go @@ -0,0 +1,437 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package fuse + +import ( + "errors" + "fmt" + "sync" + "sync/atomic" + "syscall" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/waiter" + "gvisor.dev/gvisor/tools/go_marshal/marshal" +) + +// maxActiveRequestsDefault is the default setting controlling the upper bound +// on the number of active requests at any given time. +const maxActiveRequestsDefault = 10000 + +// Ordinary requests have even IDs, while interrupts IDs are odd. +// Used to increment the unique ID for each FUSE request. +var reqIDStep uint64 = 2 + +const ( + // fuseDefaultMaxBackground is the default value for MaxBackground. + fuseDefaultMaxBackground = 12 + + // fuseDefaultCongestionThreshold is the default value for CongestionThreshold, + // and is 75% of the default maximum of MaxGround. + fuseDefaultCongestionThreshold = (fuseDefaultMaxBackground * 3 / 4) + + // fuseDefaultMaxPagesPerReq is the default value for MaxPagesPerReq. + fuseDefaultMaxPagesPerReq = 32 +) + +// Request represents a FUSE operation request that hasn't been sent to the +// server yet. +// +// +stateify savable +type Request struct { + requestEntry + + id linux.FUSEOpID + hdr *linux.FUSEHeaderIn + data []byte +} + +// Response represents an actual response from the server, including the +// response payload. +// +// +stateify savable +type Response struct { + opcode linux.FUSEOpcode + hdr linux.FUSEHeaderOut + data []byte +} + +// connection is the struct by which the sentry communicates with the FUSE server daemon. +type connection struct { + fd *DeviceFD + + // The following FUSE_INIT flags are currently unsupported by this implementation: + // - FUSE_ATOMIC_O_TRUNC: requires open(..., O_TRUNC) + // - FUSE_EXPORT_SUPPORT + // - FUSE_HANDLE_KILLPRIV + // - FUSE_POSIX_LOCKS: requires POSIX locks + // - FUSE_FLOCK_LOCKS: requires POSIX locks + // - FUSE_AUTO_INVAL_DATA: requires page caching eviction + // - FUSE_EXPLICIT_INVAL_DATA: requires page caching eviction + // - FUSE_DO_READDIRPLUS/FUSE_READDIRPLUS_AUTO: requires FUSE_READDIRPLUS implementation + // - FUSE_ASYNC_DIO + // - FUSE_POSIX_ACL: affects defaultPermissions, posixACL, xattr handler + + // initialized after receiving FUSE_INIT reply. + // Until it's set, suspend sending FUSE requests. + // Use SetInitialized() and IsInitialized() for atomic access. + initialized int32 + + // initializedChan is used to block requests before initialization. + initializedChan chan struct{} + + // blocked when there are too many outstading backgrounds requests (NumBackground == MaxBackground). + // TODO(gvisor.dev/issue/3185): update the numBackground accordingly; use a channel to block. + blocked bool + + // connected (connection established) when a new FUSE file system is created. + // Set to false when: + // umount, + // connection abort, + // device release. + connected bool + + // aborted via sysfs. + // TODO(gvisor.dev/issue/3185): abort all queued requests. + aborted bool + + // connInitError if FUSE_INIT encountered error (major version mismatch). + // Only set in INIT. + connInitError bool + + // connInitSuccess if FUSE_INIT is successful. + // Only set in INIT. + // Used for destory. + connInitSuccess bool + + // TODO(gvisor.dev/issue/3185): All the queue logic are working in progress. + + // NumberBackground is the number of requests in the background. + numBackground uint16 + + // congestionThreshold for NumBackground. + // Negotiated in FUSE_INIT. + congestionThreshold uint16 + + // maxBackground is the maximum number of NumBackground. + // Block connection when it is reached. + // Negotiated in FUSE_INIT. + maxBackground uint16 + + // numActiveBackground is the number of requests in background and has being marked as active. + numActiveBackground uint16 + + // numWating is the number of requests waiting for completion. + numWaiting uint32 + + // TODO(gvisor.dev/issue/3185): BgQueue + // some queue for background queued requests. + + // bgLock protects: + // MaxBackground, CongestionThreshold, NumBackground, + // NumActiveBackground, BgQueue, Blocked. + bgLock sync.Mutex + + // maxRead is the maximum size of a read buffer in in bytes. + maxRead uint32 + + // maxWrite is the maximum size of a write buffer in bytes. + // Negotiated in FUSE_INIT. + maxWrite uint32 + + // maxPages is the maximum number of pages for a single request to use. + // Negotiated in FUSE_INIT. + maxPages uint16 + + // minor version of the FUSE protocol. + // Negotiated and only set in INIT. + minor uint32 + + // asyncRead if read pages asynchronously. + // Negotiated and only set in INIT. + asyncRead bool + + // abortErr is true if kernel need to return an unique read error after abort. + // Negotiated and only set in INIT. + abortErr bool + + // writebackCache is true for write-back cache policy, + // false for write-through policy. + // Negotiated and only set in INIT. + writebackCache bool + + // cacheSymlinks if filesystem needs to cache READLINK responses in page cache. + // Negotiated and only set in INIT. + cacheSymlinks bool + + // bigWrites if doing multi-page cached writes. + // Negotiated and only set in INIT. + bigWrites bool + + // dontMask if filestestem does not apply umask to creation modes. + // Negotiated in INIT. + dontMask bool +} + +// newFUSEConnection creates a FUSE connection to fd. +func newFUSEConnection(_ context.Context, fd *vfs.FileDescription, maxInFlightRequests uint64) (*connection, error) { + // Mark the device as ready so it can be used. /dev/fuse can only be used if the FD was used to + // mount a FUSE filesystem. + fuseFD := fd.Impl().(*DeviceFD) + fuseFD.mounted = true + + // Create the writeBuf for the header to be stored in. + hdrLen := uint32((*linux.FUSEHeaderOut)(nil).SizeBytes()) + fuseFD.writeBuf = make([]byte, hdrLen) + fuseFD.completions = make(map[linux.FUSEOpID]*futureResponse) + fuseFD.fullQueueCh = make(chan struct{}, maxInFlightRequests) + fuseFD.writeCursor = 0 + + return &connection{ + fd: fuseFD, + maxBackground: fuseDefaultMaxBackground, + congestionThreshold: fuseDefaultCongestionThreshold, + maxPages: fuseDefaultMaxPagesPerReq, + initializedChan: make(chan struct{}), + connected: true, + }, nil +} + +// SetInitialized atomically sets the connection as initialized. +func (conn *connection) SetInitialized() { + // Unblock the requests sent before INIT. + close(conn.initializedChan) + + // Close the channel first to avoid the non-atomic situation + // where conn.initialized is true but there are + // tasks being blocked on the channel. + // And it prevents the newer tasks from gaining + // unnecessary higher chance to be issued before the blocked one. + + atomic.StoreInt32(&(conn.initialized), int32(1)) +} + +// IsInitialized atomically check if the connection is initialized. +// pairs with SetInitialized(). +func (conn *connection) Initialized() bool { + return atomic.LoadInt32(&(conn.initialized)) != 0 +} + +// NewRequest creates a new request that can be sent to the FUSE server. +func (conn *connection) NewRequest(creds *auth.Credentials, pid uint32, ino uint64, opcode linux.FUSEOpcode, payload marshal.Marshallable) (*Request, error) { + conn.fd.mu.Lock() + defer conn.fd.mu.Unlock() + conn.fd.nextOpID += linux.FUSEOpID(reqIDStep) + + hdrLen := (*linux.FUSEHeaderIn)(nil).SizeBytes() + hdr := linux.FUSEHeaderIn{ + Len: uint32(hdrLen + payload.SizeBytes()), + Opcode: opcode, + Unique: conn.fd.nextOpID, + NodeID: ino, + UID: uint32(creds.EffectiveKUID), + GID: uint32(creds.EffectiveKGID), + PID: pid, + } + + buf := make([]byte, hdr.Len) + hdr.MarshalUnsafe(buf[:hdrLen]) + payload.MarshalUnsafe(buf[hdrLen:]) + + return &Request{ + id: hdr.Unique, + hdr: &hdr, + data: buf, + }, nil +} + +// Call makes a request to the server and blocks the invoking task until a +// server responds with a response. Task should never be nil. +// Requests will not be sent before the connection is initialized. +// For async tasks, use CallAsync(). +func (conn *connection) Call(t *kernel.Task, r *Request) (*Response, error) { + // Block requests sent before connection is initalized. + if !conn.Initialized() { + if err := t.Block(conn.initializedChan); err != nil { + return nil, err + } + } + + return conn.call(t, r) +} + +// CallAsync makes an async (aka background) request. +// Those requests either do not expect a response (e.g. release) or +// the response should be handled by others (e.g. init). +// Return immediately unless the connection is blocked (before initialization). +// Async call example: init, release, forget, aio, interrupt. +// When the Request is FUSE_INIT, it will not be blocked before initialization. +func (conn *connection) CallAsync(t *kernel.Task, r *Request) error { + // Block requests sent before connection is initalized. + if !conn.Initialized() && r.hdr.Opcode != linux.FUSE_INIT { + if err := t.Block(conn.initializedChan); err != nil { + return err + } + } + + // This should be the only place that invokes call() with a nil task. + _, err := conn.call(nil, r) + return err +} + +// call makes a call without blocking checks. +func (conn *connection) call(t *kernel.Task, r *Request) (*Response, error) { + if !conn.connected { + return nil, syserror.ENOTCONN + } + + if conn.connInitError { + return nil, syserror.ECONNREFUSED + } + + fut, err := conn.callFuture(t, r) + if err != nil { + return nil, err + } + + return fut.resolve(t) +} + +// Error returns the error of the FUSE call. +func (r *Response) Error() error { + errno := r.hdr.Error + if errno >= 0 { + return nil + } + + sysErrNo := syscall.Errno(-errno) + return error(sysErrNo) +} + +// UnmarshalPayload unmarshals the response data into m. +func (r *Response) UnmarshalPayload(m marshal.Marshallable) error { + hdrLen := r.hdr.SizeBytes() + haveDataLen := r.hdr.Len - uint32(hdrLen) + wantDataLen := uint32(m.SizeBytes()) + + if haveDataLen < wantDataLen { + return fmt.Errorf("payload too small. Minimum data lenth required: %d, but got data length %d", wantDataLen, haveDataLen) + } + + m.UnmarshalUnsafe(r.data[hdrLen:]) + return nil +} + +// callFuture makes a request to the server and returns a future response. +// Call resolve() when the response needs to be fulfilled. +func (conn *connection) callFuture(t *kernel.Task, r *Request) (*futureResponse, error) { + conn.fd.mu.Lock() + defer conn.fd.mu.Unlock() + + // Is the queue full? + // + // We must busy wait here until the request can be queued. We don't + // block on the fd.fullQueueCh with a lock - so after being signalled, + // before we acquire the lock, it is possible that a barging task enters + // and queues a request. As a result, upon acquiring the lock we must + // again check if the room is available. + // + // This can potentially starve a request forever but this can only happen + // if there are always too many ongoing requests all the time. The + // supported maxActiveRequests setting should be really high to avoid this. + for conn.fd.numActiveRequests == conn.fd.fs.opts.maxActiveRequests { + if t == nil { + // Since there is no task that is waiting. We must error out. + return nil, errors.New("FUSE request queue full") + } + + log.Infof("Blocking request %v from being queued. Too many active requests: %v", + r.id, conn.fd.numActiveRequests) + conn.fd.mu.Unlock() + err := t.Block(conn.fd.fullQueueCh) + conn.fd.mu.Lock() + if err != nil { + return nil, err + } + } + + return conn.callFutureLocked(t, r) +} + +// callFutureLocked makes a request to the server and returns a future response. +func (conn *connection) callFutureLocked(t *kernel.Task, r *Request) (*futureResponse, error) { + conn.fd.queue.PushBack(r) + conn.fd.numActiveRequests += 1 + fut := newFutureResponse(r.hdr.Opcode) + conn.fd.completions[r.id] = fut + + // Signal the readers that there is something to read. + conn.fd.waitQueue.Notify(waiter.EventIn) + + return fut, nil +} + +// futureResponse represents an in-flight request, that may or may not have +// completed yet. Convert it to a resolved Response by calling Resolve, but note +// that this may block. +// +// +stateify savable +type futureResponse struct { + opcode linux.FUSEOpcode + ch chan struct{} + hdr *linux.FUSEHeaderOut + data []byte +} + +// newFutureResponse creates a future response to a FUSE request. +func newFutureResponse(opcode linux.FUSEOpcode) *futureResponse { + return &futureResponse{ + opcode: opcode, + ch: make(chan struct{}), + } +} + +// resolve blocks the task until the server responds to its corresponding request, +// then returns a resolved response. +func (f *futureResponse) resolve(t *kernel.Task) (*Response, error) { + // If there is no Task associated with this request - then we don't try to resolve + // the response. Instead, the task writing the response (proxy to the server) will + // process the response on our behalf. + if t == nil { + log.Infof("fuse.Response.resolve: Not waiting on a response from server.") + return nil, nil + } + + if err := t.Block(f.ch); err != nil { + return nil, err + } + + return f.getResponse(), nil +} + +// getResponse creates a Response from the data the futureResponse has. +func (f *futureResponse) getResponse() *Response { + return &Response{ + opcode: f.opcode, + hdr: *f.hdr, + data: f.data, + } +} diff --git a/pkg/sentry/fsimpl/fuse/dev.go b/pkg/sentry/fsimpl/fuse/dev.go new file mode 100644 index 000000000..2225076bc --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/dev.go @@ -0,0 +1,397 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package fuse + +import ( + "syscall" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" +) + +const fuseDevMinor = 229 + +// fuseDevice implements vfs.Device for /dev/fuse. +type fuseDevice struct{} + +// Open implements vfs.Device.Open. +func (fuseDevice) Open(ctx context.Context, mnt *vfs.Mount, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + if !kernel.FUSEEnabled { + return nil, syserror.ENOENT + } + + var fd DeviceFD + if err := fd.vfsfd.Init(&fd, opts.Flags, mnt, vfsd, &vfs.FileDescriptionOptions{ + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return &fd.vfsfd, nil +} + +// DeviceFD implements vfs.FileDescriptionImpl for /dev/fuse. +type DeviceFD struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.DentryMetadataFileDescriptionImpl + vfs.NoLockFD + + // mounted specifies whether a FUSE filesystem was mounted using the DeviceFD. + mounted bool + + // nextOpID is used to create new requests. + nextOpID linux.FUSEOpID + + // queue is the list of requests that need to be processed by the FUSE server. + queue requestList + + // numActiveRequests is the number of requests made by the Sentry that has + // yet to be responded to. + numActiveRequests uint64 + + // completions is used to map a request to its response. A Writer will use this + // to notify the caller of a completed response. + completions map[linux.FUSEOpID]*futureResponse + + writeCursor uint32 + + // writeBuf is the memory buffer used to copy in the FUSE out header from + // userspace. + writeBuf []byte + + // writeCursorFR current FR being copied from server. + writeCursorFR *futureResponse + + // mu protects all the queues, maps, buffers and cursors and nextOpID. + mu sync.Mutex + + // waitQueue is used to notify interested parties when the device becomes + // readable or writable. + waitQueue waiter.Queue + + // fullQueueCh is a channel used to synchronize the readers with the writers. + // Writers (inbound requests to the filesystem) block if there are too many + // unprocessed in-flight requests. + fullQueueCh chan struct{} + + // fs is the FUSE filesystem that this FD is being used for. + fs *filesystem +} + +// Release implements vfs.FileDescriptionImpl.Release. +func (fd *DeviceFD) Release() { + fd.fs.conn.connected = false +} + +// PRead implements vfs.FileDescriptionImpl.PRead. +func (fd *DeviceFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + + return 0, syserror.ENOSYS +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (fd *DeviceFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + + // We require that any Read done on this filesystem have a sane minimum + // read buffer. It must have the capacity for the fixed parts of any request + // header (Linux uses the request header and the FUSEWriteIn header for this + // calculation) + the negotiated MaxWrite room for the data. + minBuffSize := linux.FUSE_MIN_READ_BUFFER + inHdrLen := uint32((*linux.FUSEHeaderIn)(nil).SizeBytes()) + writeHdrLen := uint32((*linux.FUSEWriteIn)(nil).SizeBytes()) + negotiatedMinBuffSize := inHdrLen + writeHdrLen + fd.fs.conn.maxWrite + if minBuffSize < negotiatedMinBuffSize { + minBuffSize = negotiatedMinBuffSize + } + + // If the read buffer is too small, error out. + if dst.NumBytes() < int64(minBuffSize) { + return 0, syserror.EINVAL + } + + fd.mu.Lock() + defer fd.mu.Unlock() + return fd.readLocked(ctx, dst, opts) +} + +// readLocked implements the reading of the fuse device while locked with DeviceFD.mu. +func (fd *DeviceFD) readLocked(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + if fd.queue.Empty() { + return 0, syserror.ErrWouldBlock + } + + var readCursor uint32 + var bytesRead int64 + for { + req := fd.queue.Front() + if dst.NumBytes() < int64(req.hdr.Len) { + // The request is too large. Cannot process it. All requests must be smaller than the + // negotiated size as specified by Connection.MaxWrite set as part of the FUSE_INIT + // handshake. + errno := -int32(syscall.EIO) + if req.hdr.Opcode == linux.FUSE_SETXATTR { + errno = -int32(syscall.E2BIG) + } + + // Return the error to the calling task. + if err := fd.sendError(ctx, errno, req); err != nil { + return 0, err + } + + // We're done with this request. + fd.queue.Remove(req) + + // Restart the read as this request was invalid. + log.Warningf("fuse.DeviceFD.Read: request found was too large. Restarting read.") + return fd.readLocked(ctx, dst, opts) + } + + n, err := dst.CopyOut(ctx, req.data[readCursor:]) + if err != nil { + return 0, err + } + readCursor += uint32(n) + bytesRead += int64(n) + + if readCursor >= req.hdr.Len { + // Fully done with this req, remove it from the queue. + fd.queue.Remove(req) + break + } + } + + return bytesRead, nil +} + +// PWrite implements vfs.FileDescriptionImpl.PWrite. +func (fd *DeviceFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + + return 0, syserror.ENOSYS +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (fd *DeviceFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + fd.mu.Lock() + defer fd.mu.Unlock() + return fd.writeLocked(ctx, src, opts) +} + +// writeLocked implements writing to the fuse device while locked with DeviceFD.mu. +func (fd *DeviceFD) writeLocked(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + + var cn, n int64 + hdrLen := uint32((*linux.FUSEHeaderOut)(nil).SizeBytes()) + + for src.NumBytes() > 0 { + if fd.writeCursorFR != nil { + // Already have common header, and we're now copying the payload. + wantBytes := fd.writeCursorFR.hdr.Len + + // Note that the FR data doesn't have the header. Copy it over if its necessary. + if fd.writeCursorFR.data == nil { + fd.writeCursorFR.data = make([]byte, wantBytes) + } + + bytesCopied, err := src.CopyIn(ctx, fd.writeCursorFR.data[fd.writeCursor:wantBytes]) + if err != nil { + return 0, err + } + src = src.DropFirst(bytesCopied) + + cn = int64(bytesCopied) + n += cn + fd.writeCursor += uint32(cn) + if fd.writeCursor == wantBytes { + // Done reading this full response. Clean up and unblock the + // initiator. + break + } + + // Check if we have more data in src. + continue + } + + // Assert that the header isn't read into the writeBuf yet. + if fd.writeCursor >= hdrLen { + return 0, syserror.EINVAL + } + + // We don't have the full common response header yet. + wantBytes := hdrLen - fd.writeCursor + bytesCopied, err := src.CopyIn(ctx, fd.writeBuf[fd.writeCursor:wantBytes]) + if err != nil { + return 0, err + } + src = src.DropFirst(bytesCopied) + + cn = int64(bytesCopied) + n += cn + fd.writeCursor += uint32(cn) + if fd.writeCursor == hdrLen { + // Have full header in the writeBuf. Use it to fetch the actual futureResponse + // from the device's completions map. + var hdr linux.FUSEHeaderOut + hdr.UnmarshalBytes(fd.writeBuf) + + // We have the header now and so the writeBuf has served its purpose. + // We could reset it manually here but instead of doing that, at the + // end of the write, the writeCursor will be set to 0 thereby allowing + // the next request to overwrite whats in the buffer, + + fut, ok := fd.completions[hdr.Unique] + if !ok { + // Server sent us a response for a request we never sent? + return 0, syserror.EINVAL + } + + delete(fd.completions, hdr.Unique) + + // Copy over the header into the future response. The rest of the payload + // will be copied over to the FR's data in the next iteration. + fut.hdr = &hdr + fd.writeCursorFR = fut + + // Next iteration will now try read the complete request, if src has + // any data remaining. Otherwise we're done. + } + } + + if fd.writeCursorFR != nil { + if err := fd.sendResponse(ctx, fd.writeCursorFR); err != nil { + return 0, err + } + + // Ready the device for the next request. + fd.writeCursorFR = nil + fd.writeCursor = 0 + } + + return n, nil +} + +// Readiness implements vfs.FileDescriptionImpl.Readiness. +func (fd *DeviceFD) Readiness(mask waiter.EventMask) waiter.EventMask { + var ready waiter.EventMask + ready |= waiter.EventOut // FD is always writable + if !fd.queue.Empty() { + // Have reqs available, FD is readable. + ready |= waiter.EventIn + } + + return ready & mask +} + +// EventRegister implements waiter.Waitable.EventRegister. +func (fd *DeviceFD) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + fd.waitQueue.EventRegister(e, mask) +} + +// EventUnregister implements waiter.Waitable.EventUnregister. +func (fd *DeviceFD) EventUnregister(e *waiter.Entry) { + fd.waitQueue.EventUnregister(e) +} + +// Seek implements vfs.FileDescriptionImpl.Seek. +func (fd *DeviceFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + // Operations on /dev/fuse don't make sense until a FUSE filesystem is mounted. + if !fd.mounted { + return 0, syserror.EPERM + } + + return 0, syserror.ENOSYS +} + +// sendResponse sends a response to the waiting task (if any). +func (fd *DeviceFD) sendResponse(ctx context.Context, fut *futureResponse) error { + // See if the running task need to perform some action before returning. + // Since we just finished writing the future, we can be sure that + // getResponse generates a populated response. + if err := fd.noReceiverAction(ctx, fut.getResponse()); err != nil { + return err + } + + // Signal that the queue is no longer full. + select { + case fd.fullQueueCh <- struct{}{}: + default: + } + fd.numActiveRequests -= 1 + + // Signal the task waiting on a response. + close(fut.ch) + return nil +} + +// sendError sends an error response to the waiting task (if any). +func (fd *DeviceFD) sendError(ctx context.Context, errno int32, req *Request) error { + // Return the error to the calling task. + outHdrLen := uint32((*linux.FUSEHeaderOut)(nil).SizeBytes()) + respHdr := linux.FUSEHeaderOut{ + Len: outHdrLen, + Error: errno, + Unique: req.hdr.Unique, + } + + fut, ok := fd.completions[respHdr.Unique] + if !ok { + // Server sent us a response for a request we never sent? + return syserror.EINVAL + } + delete(fd.completions, respHdr.Unique) + + fut.hdr = &respHdr + if err := fd.sendResponse(ctx, fut); err != nil { + return err + } + + return nil +} + +// noReceiverAction has the calling kernel.Task do some action if its known that no +// receiver is going to be waiting on the future channel. This is to be used by: +// FUSE_INIT. +func (fd *DeviceFD) noReceiverAction(ctx context.Context, r *Response) error { + if r.opcode == linux.FUSE_INIT { + creds := auth.CredentialsFromContext(ctx) + rootUserNs := kernel.KernelFromContext(ctx).RootUserNamespace() + return fd.fs.conn.InitRecv(r, creds.HasCapabilityIn(linux.CAP_SYS_ADMIN, rootUserNs)) + } + + return nil +} diff --git a/pkg/sentry/fsimpl/fuse/dev_test.go b/pkg/sentry/fsimpl/fuse/dev_test.go new file mode 100644 index 000000000..84c222ad6 --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/dev_test.go @@ -0,0 +1,428 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package fuse + +import ( + "fmt" + "io" + "math/rand" + "testing" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/testutil" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" + "gvisor.dev/gvisor/tools/go_marshal/marshal" +) + +// echoTestOpcode is the Opcode used during testing. The server used in tests +// will simply echo the payload back with the appropriate headers. +const echoTestOpcode linux.FUSEOpcode = 1000 + +type testPayload struct { + data uint32 +} + +// TestFUSECommunication tests that the communication layer between the Sentry and the +// FUSE server daemon works as expected. +func TestFUSECommunication(t *testing.T) { + s := setup(t) + defer s.Destroy() + + k := kernel.KernelFromContext(s.Ctx) + creds := auth.CredentialsFromContext(s.Ctx) + + // Create test cases with different number of concurrent clients and servers. + testCases := []struct { + Name string + NumClients int + NumServers int + MaxActiveRequests uint64 + }{ + { + Name: "SingleClientSingleServer", + NumClients: 1, + NumServers: 1, + MaxActiveRequests: maxActiveRequestsDefault, + }, + { + Name: "SingleClientMultipleServers", + NumClients: 1, + NumServers: 10, + MaxActiveRequests: maxActiveRequestsDefault, + }, + { + Name: "MultipleClientsSingleServer", + NumClients: 10, + NumServers: 1, + MaxActiveRequests: maxActiveRequestsDefault, + }, + { + Name: "MultipleClientsMultipleServers", + NumClients: 10, + NumServers: 10, + MaxActiveRequests: maxActiveRequestsDefault, + }, + { + Name: "RequestCapacityFull", + NumClients: 10, + NumServers: 1, + MaxActiveRequests: 1, + }, + { + Name: "RequestCapacityContinuouslyFull", + NumClients: 100, + NumServers: 2, + MaxActiveRequests: 2, + }, + } + + for _, testCase := range testCases { + t.Run(testCase.Name, func(t *testing.T) { + conn, fd, err := newTestConnection(s, k, testCase.MaxActiveRequests) + if err != nil { + t.Fatalf("newTestConnection: %v", err) + } + + clientsDone := make([]chan struct{}, testCase.NumClients) + serversDone := make([]chan struct{}, testCase.NumServers) + serversKill := make([]chan struct{}, testCase.NumServers) + + // FUSE clients. + for i := 0; i < testCase.NumClients; i++ { + clientsDone[i] = make(chan struct{}) + go func(i int) { + fuseClientRun(t, s, k, conn, creds, uint32(i), uint64(i), clientsDone[i]) + }(i) + } + + // FUSE servers. + for j := 0; j < testCase.NumServers; j++ { + serversDone[j] = make(chan struct{}) + serversKill[j] = make(chan struct{}, 1) // The kill command shouldn't block. + go func(j int) { + fuseServerRun(t, s, k, fd, serversDone[j], serversKill[j]) + }(j) + } + + // Tear down. + // + // Make sure all the clients are done. + for i := 0; i < testCase.NumClients; i++ { + <-clientsDone[i] + } + + // Kill any server that is potentially waiting. + for j := 0; j < testCase.NumServers; j++ { + serversKill[j] <- struct{}{} + } + + // Make sure all the servers are done. + for j := 0; j < testCase.NumServers; j++ { + <-serversDone[j] + } + }) + } +} + +// CallTest makes a request to the server and blocks the invoking +// goroutine until a server responds with a response. Doesn't block +// a kernel.Task. Analogous to Connection.Call but used for testing. +func CallTest(conn *connection, t *kernel.Task, r *Request, i uint32) (*Response, error) { + conn.fd.mu.Lock() + + // Wait until we're certain that a new request can be processed. + for conn.fd.numActiveRequests == conn.fd.fs.opts.maxActiveRequests { + conn.fd.mu.Unlock() + select { + case <-conn.fd.fullQueueCh: + } + conn.fd.mu.Lock() + } + + fut, err := conn.callFutureLocked(t, r) // No task given. + conn.fd.mu.Unlock() + + if err != nil { + return nil, err + } + + // Resolve the response. + // + // Block without a task. + select { + case <-fut.ch: + } + + // A response is ready. Resolve and return it. + return fut.getResponse(), nil +} + +// ReadTest is analogous to vfs.FileDescription.Read and reads from the FUSE +// device. However, it does so by - not blocking the task that is calling - and +// instead just waits on a channel. The behaviour is essentially the same as +// DeviceFD.Read except it guarantees that the task is not blocked. +func ReadTest(serverTask *kernel.Task, fd *vfs.FileDescription, inIOseq usermem.IOSequence, killServer chan struct{}) (int64, bool, error) { + var err error + var n, total int64 + + dev := fd.Impl().(*DeviceFD) + + // Register for notifications. + w, ch := waiter.NewChannelEntry(nil) + dev.EventRegister(&w, waiter.EventIn) + for { + // Issue the request and break out if it completes with anything other than + // "would block". + n, err = dev.Read(serverTask, inIOseq, vfs.ReadOptions{}) + total += n + if err != syserror.ErrWouldBlock { + break + } + + // Wait for a notification that we should retry. + // Emulate the blocking for when no requests are available + select { + case <-ch: + case <-killServer: + // Server killed by the main program. + return 0, true, nil + } + } + + dev.EventUnregister(&w) + return total, false, err +} + +// fuseClientRun emulates all the actions of a normal FUSE request. It creates +// a header, a payload, calls the server, waits for the response, and processes +// the response. +func fuseClientRun(t *testing.T, s *testutil.System, k *kernel.Kernel, conn *connection, creds *auth.Credentials, pid uint32, inode uint64, clientDone chan struct{}) { + defer func() { clientDone <- struct{}{} }() + + tc := k.NewThreadGroup(nil, k.RootPIDNamespace(), kernel.NewSignalHandlers(), linux.SIGCHLD, k.GlobalInit().Limits()) + clientTask, err := testutil.CreateTask(s.Ctx, fmt.Sprintf("fuse-client-%v", pid), tc, s.MntNs, s.Root, s.Root) + if err != nil { + t.Fatal(err) + } + testObj := &testPayload{ + data: rand.Uint32(), + } + + req, err := conn.NewRequest(creds, pid, inode, echoTestOpcode, testObj) + if err != nil { + t.Fatalf("NewRequest creation failed: %v", err) + } + + // Queue up a request. + // Analogous to Call except it doesn't block on the task. + resp, err := CallTest(conn, clientTask, req, pid) + if err != nil { + t.Fatalf("CallTaskNonBlock failed: %v", err) + } + + if err = resp.Error(); err != nil { + t.Fatalf("Server responded with an error: %v", err) + } + + var respTestPayload testPayload + if err := resp.UnmarshalPayload(&respTestPayload); err != nil { + t.Fatalf("Unmarshalling payload error: %v", err) + } + + if resp.hdr.Unique != req.hdr.Unique { + t.Fatalf("got response for another request. Expected response for req %v but got response for req %v", + req.hdr.Unique, resp.hdr.Unique) + } + + if respTestPayload.data != testObj.data { + t.Fatalf("read incorrect data. Data expected: %v, but got %v", testObj.data, respTestPayload.data) + } + +} + +// fuseServerRun creates a task and emulates all the actions of a simple FUSE server +// that simply reads a request and echos the same struct back as a response using the +// appropriate headers. +func fuseServerRun(t *testing.T, s *testutil.System, k *kernel.Kernel, fd *vfs.FileDescription, serverDone, killServer chan struct{}) { + defer func() { serverDone <- struct{}{} }() + + // Create the tasks that the server will be using. + tc := k.NewThreadGroup(nil, k.RootPIDNamespace(), kernel.NewSignalHandlers(), linux.SIGCHLD, k.GlobalInit().Limits()) + var readPayload testPayload + + serverTask, err := testutil.CreateTask(s.Ctx, "fuse-server", tc, s.MntNs, s.Root, s.Root) + if err != nil { + t.Fatal(err) + } + + // Read the request. + for { + inHdrLen := uint32((*linux.FUSEHeaderIn)(nil).SizeBytes()) + payloadLen := uint32(readPayload.SizeBytes()) + + // The raed buffer must meet some certain size criteria. + buffSize := inHdrLen + payloadLen + if buffSize < linux.FUSE_MIN_READ_BUFFER { + buffSize = linux.FUSE_MIN_READ_BUFFER + } + inBuf := make([]byte, buffSize) + inIOseq := usermem.BytesIOSequence(inBuf) + + n, serverKilled, err := ReadTest(serverTask, fd, inIOseq, killServer) + if err != nil { + t.Fatalf("Read failed :%v", err) + } + + // Server should shut down. No new requests are going to be made. + if serverKilled { + break + } + + if n <= 0 { + t.Fatalf("Read read no bytes") + } + + var readFUSEHeaderIn linux.FUSEHeaderIn + readFUSEHeaderIn.UnmarshalUnsafe(inBuf[:inHdrLen]) + readPayload.UnmarshalUnsafe(inBuf[inHdrLen : inHdrLen+payloadLen]) + + if readFUSEHeaderIn.Opcode != echoTestOpcode { + t.Fatalf("read incorrect data. Header: %v, Payload: %v", readFUSEHeaderIn, readPayload) + } + + // Write the response. + outHdrLen := uint32((*linux.FUSEHeaderOut)(nil).SizeBytes()) + outBuf := make([]byte, outHdrLen+payloadLen) + outHeader := linux.FUSEHeaderOut{ + Len: outHdrLen + payloadLen, + Error: 0, + Unique: readFUSEHeaderIn.Unique, + } + + // Echo the payload back. + outHeader.MarshalUnsafe(outBuf[:outHdrLen]) + readPayload.MarshalUnsafe(outBuf[outHdrLen:]) + outIOseq := usermem.BytesIOSequence(outBuf) + + n, err = fd.Write(s.Ctx, outIOseq, vfs.WriteOptions{}) + if err != nil { + t.Fatalf("Write failed :%v", err) + } + } +} + +func setup(t *testing.T) *testutil.System { + k, err := testutil.Boot() + if err != nil { + t.Fatalf("Error creating kernel: %v", err) + } + + ctx := k.SupervisorContext() + creds := auth.CredentialsFromContext(ctx) + + k.VFS().MustRegisterFilesystemType(Name, &FilesystemType{}, &vfs.RegisterFilesystemTypeOptions{ + AllowUserList: true, + AllowUserMount: true, + }) + + mntns, err := k.VFS().NewMountNamespace(ctx, creds, "", "tmpfs", &vfs.GetFilesystemOptions{}) + if err != nil { + t.Fatalf("NewMountNamespace(): %v", err) + } + + return testutil.NewSystem(ctx, t, k.VFS(), mntns) +} + +// newTestConnection creates a fuse connection that the sentry can communicate with +// and the FD for the server to communicate with. +func newTestConnection(system *testutil.System, k *kernel.Kernel, maxActiveRequests uint64) (*connection, *vfs.FileDescription, error) { + vfsObj := &vfs.VirtualFilesystem{} + fuseDev := &DeviceFD{} + + if err := vfsObj.Init(); err != nil { + return nil, nil, err + } + + vd := vfsObj.NewAnonVirtualDentry("genCountFD") + defer vd.DecRef() + if err := fuseDev.vfsfd.Init(fuseDev, linux.O_RDWR|linux.O_CREAT, vd.Mount(), vd.Dentry(), &vfs.FileDescriptionOptions{}); err != nil { + return nil, nil, err + } + + fsopts := filesystemOptions{ + maxActiveRequests: maxActiveRequests, + } + fs, err := NewFUSEFilesystem(system.Ctx, 0, &fsopts, &fuseDev.vfsfd) + if err != nil { + return nil, nil, err + } + + return fs.conn, &fuseDev.vfsfd, nil +} + +// SizeBytes implements marshal.Marshallable.SizeBytes. +func (t *testPayload) SizeBytes() int { + return 4 +} + +// MarshalBytes implements marshal.Marshallable.MarshalBytes. +func (t *testPayload) MarshalBytes(dst []byte) { + usermem.ByteOrder.PutUint32(dst[:4], t.data) +} + +// UnmarshalBytes implements marshal.Marshallable.UnmarshalBytes. +func (t *testPayload) UnmarshalBytes(src []byte) { + *t = testPayload{data: usermem.ByteOrder.Uint32(src[:4])} +} + +// Packed implements marshal.Marshallable.Packed. +func (t *testPayload) Packed() bool { + return true +} + +// MarshalUnsafe implements marshal.Marshallable.MarshalUnsafe. +func (t *testPayload) MarshalUnsafe(dst []byte) { + t.MarshalBytes(dst) +} + +// UnmarshalUnsafe implements marshal.Marshallable.UnmarshalUnsafe. +func (t *testPayload) UnmarshalUnsafe(src []byte) { + t.UnmarshalBytes(src) +} + +// CopyOutN implements marshal.Marshallable.CopyOutN. +func (t *testPayload) CopyOutN(task marshal.Task, addr usermem.Addr, limit int) (int, error) { + panic("not implemented") +} + +// CopyOut implements marshal.Marshallable.CopyOut. +func (t *testPayload) CopyOut(task marshal.Task, addr usermem.Addr) (int, error) { + panic("not implemented") +} + +// CopyIn implements marshal.Marshallable.CopyIn. +func (t *testPayload) CopyIn(task marshal.Task, addr usermem.Addr) (int, error) { + panic("not implemented") +} + +// WriteTo implements io.WriterTo.WriteTo. +func (t *testPayload) WriteTo(w io.Writer) (int64, error) { + panic("not implemented") +} diff --git a/pkg/sentry/fsimpl/fuse/fusefs.go b/pkg/sentry/fsimpl/fuse/fusefs.go new file mode 100644 index 000000000..200a93bbf --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/fusefs.go @@ -0,0 +1,228 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +// Package fuse implements fusefs. +package fuse + +import ( + "strconv" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" +) + +// Name is the default filesystem name. +const Name = "fuse" + +// FilesystemType implements vfs.FilesystemType. +type FilesystemType struct{} + +type filesystemOptions struct { + // userID specifies the numeric uid of the mount owner. + // This option should not be specified by the filesystem owner. + // It is set by libfuse (or, if libfuse is not used, must be set + // by the filesystem itself). For more information, see man page + // for fuse(8) + userID uint32 + + // groupID specifies the numeric gid of the mount owner. + // This option should not be specified by the filesystem owner. + // It is set by libfuse (or, if libfuse is not used, must be set + // by the filesystem itself). For more information, see man page + // for fuse(8) + groupID uint32 + + // rootMode specifies the the file mode of the filesystem's root. + rootMode linux.FileMode + + // maxActiveRequests specifies the maximum number of active requests that can + // exist at any time. Any further requests will block when trying to + // Call the server. + maxActiveRequests uint64 +} + +// filesystem implements vfs.FilesystemImpl. +type filesystem struct { + kernfs.Filesystem + devMinor uint32 + + // conn is used for communication between the FUSE server + // daemon and the sentry fusefs. + conn *connection + + // opts is the options the fusefs is initialized with. + opts *filesystemOptions +} + +// Name implements vfs.FilesystemType.Name. +func (FilesystemType) Name() string { + return Name +} + +// GetFilesystem implements vfs.FilesystemType.GetFilesystem. +func (fsType FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) { + devMinor, err := vfsObj.GetAnonBlockDevMinor() + if err != nil { + return nil, nil, err + } + + var fsopts filesystemOptions + mopts := vfs.GenericParseMountOptions(opts.Data) + deviceDescriptorStr, ok := mopts["fd"] + if !ok { + log.Warningf("%s.GetFilesystem: communication file descriptor N (obtained by opening /dev/fuse) must be specified as 'fd=N'", fsType.Name()) + return nil, nil, syserror.EINVAL + } + delete(mopts, "fd") + + deviceDescriptor, err := strconv.ParseInt(deviceDescriptorStr, 10 /* base */, 32 /* bitSize */) + if err != nil { + return nil, nil, err + } + + kernelTask := kernel.TaskFromContext(ctx) + if kernelTask == nil { + log.Warningf("%s.GetFilesystem: couldn't get kernel task from context", fsType.Name()) + return nil, nil, syserror.EINVAL + } + fuseFd := kernelTask.GetFileVFS2(int32(deviceDescriptor)) + + // Parse and set all the other supported FUSE mount options. + // TODO(gVisor.dev/issue/3229): Expand the supported mount options. + if userIDStr, ok := mopts["user_id"]; ok { + delete(mopts, "user_id") + userID, err := strconv.ParseUint(userIDStr, 10, 32) + if err != nil { + log.Warningf("%s.GetFilesystem: invalid user_id: user_id=%s", fsType.Name(), userIDStr) + return nil, nil, syserror.EINVAL + } + fsopts.userID = uint32(userID) + } + + if groupIDStr, ok := mopts["group_id"]; ok { + delete(mopts, "group_id") + groupID, err := strconv.ParseUint(groupIDStr, 10, 32) + if err != nil { + log.Warningf("%s.GetFilesystem: invalid group_id: group_id=%s", fsType.Name(), groupIDStr) + return nil, nil, syserror.EINVAL + } + fsopts.groupID = uint32(groupID) + } + + rootMode := linux.FileMode(0777) + modeStr, ok := mopts["rootmode"] + if ok { + delete(mopts, "rootmode") + mode, err := strconv.ParseUint(modeStr, 8, 32) + if err != nil { + log.Warningf("%s.GetFilesystem: invalid mode: %q", fsType.Name(), modeStr) + return nil, nil, syserror.EINVAL + } + rootMode = linux.FileMode(mode) + } + fsopts.rootMode = rootMode + + // Set the maxInFlightRequests option. + fsopts.maxActiveRequests = maxActiveRequestsDefault + + // Check for unparsed options. + if len(mopts) != 0 { + log.Warningf("%s.GetFilesystem: unknown options: %v", fsType.Name(), mopts) + return nil, nil, syserror.EINVAL + } + + // Create a new FUSE filesystem. + fs, err := NewFUSEFilesystem(ctx, devMinor, &fsopts, fuseFd) + if err != nil { + log.Warningf("%s.NewFUSEFilesystem: failed with error: %v", fsType.Name(), err) + return nil, nil, err + } + + fs.VFSFilesystem().Init(vfsObj, &fsType, fs) + + // Send a FUSE_INIT request to the FUSE daemon server before returning. + // This call is not blocking. + if err := fs.conn.InitSend(creds, uint32(kernelTask.ThreadID())); err != nil { + log.Warningf("%s.InitSend: failed with error: %v", fsType.Name(), err) + return nil, nil, err + } + + // root is the fusefs root directory. + root := fs.newInode(creds, fsopts.rootMode) + + return fs.VFSFilesystem(), root.VFSDentry(), nil +} + +// NewFUSEFilesystem creates a new FUSE filesystem. +func NewFUSEFilesystem(ctx context.Context, devMinor uint32, opts *filesystemOptions, device *vfs.FileDescription) (*filesystem, error) { + fs := &filesystem{ + devMinor: devMinor, + opts: opts, + } + + conn, err := newFUSEConnection(ctx, device, opts.maxActiveRequests) + if err != nil { + log.Warningf("fuse.NewFUSEFilesystem: NewFUSEConnection failed with error: %v", err) + return nil, syserror.EINVAL + } + + fs.conn = conn + fuseFD := device.Impl().(*DeviceFD) + fuseFD.fs = fs + + return fs, nil +} + +// Release implements vfs.FilesystemImpl.Release. +func (fs *filesystem) Release() { + fs.Filesystem.VFSFilesystem().VirtualFilesystem().PutAnonBlockDevMinor(fs.devMinor) + fs.Filesystem.Release() +} + +// inode implements kernfs.Inode. +type inode struct { + kernfs.InodeAttrs + kernfs.InodeNoDynamicLookup + kernfs.InodeNotSymlink + kernfs.InodeDirectoryNoNewChildren + kernfs.OrderedChildren + + locks vfs.FileLocks + + dentry kernfs.Dentry +} + +func (fs *filesystem) newInode(creds *auth.Credentials, mode linux.FileMode) *kernfs.Dentry { + i := &inode{} + i.InodeAttrs.Init(creds, linux.UNNAMED_MAJOR, fs.devMinor, fs.NextIno(), linux.ModeDirectory|0755) + i.OrderedChildren.Init(kernfs.OrderedChildrenOptions{}) + i.dentry.Init(i) + + return &i.dentry +} + +// Open implements kernfs.Inode.Open. +func (i *inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) + if err != nil { + return nil, err + } + return fd.VFSFileDescription(), nil +} diff --git a/pkg/sentry/fsimpl/fuse/init.go b/pkg/sentry/fsimpl/fuse/init.go new file mode 100644 index 000000000..779c2bd3f --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/init.go @@ -0,0 +1,166 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package fuse + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" +) + +// consts used by FUSE_INIT negotiation. +const ( + // fuseMaxMaxPages is the maximum value for MaxPages received in InitOut. + // Follow the same behavior as unix fuse implementation. + fuseMaxMaxPages = 256 + + // Maximum value for the time granularity for file time stamps, 1s. + // Follow the same behavior as unix fuse implementation. + fuseMaxTimeGranNs = 1000000000 + + // Minimum value for MaxWrite. + // Follow the same behavior as unix fuse implementation. + fuseMinMaxWrite = 4096 + + // Temporary default value for max readahead, 128kb. + fuseDefaultMaxReadahead = 131072 + + // The FUSE_INIT_IN flags sent to the daemon. + // TODO(gvisor.dev/issue/3199): complete the flags. + fuseDefaultInitFlags = linux.FUSE_MAX_PAGES +) + +// Adjustable maximums for Connection's cogestion control parameters. +// Used as the upperbound of the config values. +// Currently we do not support adjustment to them. +var ( + MaxUserBackgroundRequest uint16 = fuseDefaultMaxBackground + MaxUserCongestionThreshold uint16 = fuseDefaultCongestionThreshold +) + +// InitSend sends a FUSE_INIT request. +func (conn *connection) InitSend(creds *auth.Credentials, pid uint32) error { + in := linux.FUSEInitIn{ + Major: linux.FUSE_KERNEL_VERSION, + Minor: linux.FUSE_KERNEL_MINOR_VERSION, + // TODO(gvisor.dev/issue/3196): find appropriate way to calculate this + MaxReadahead: fuseDefaultMaxReadahead, + Flags: fuseDefaultInitFlags, + } + + req, err := conn.NewRequest(creds, pid, 0, linux.FUSE_INIT, &in) + if err != nil { + return err + } + + // Since there is no task to block on and FUSE_INIT is the request + // to unblock other requests, use nil. + return conn.CallAsync(nil, req) +} + +// InitRecv receives a FUSE_INIT reply and process it. +func (conn *connection) InitRecv(res *Response, hasSysAdminCap bool) error { + if err := res.Error(); err != nil { + return err + } + + var out linux.FUSEInitOut + if err := res.UnmarshalPayload(&out); err != nil { + return err + } + + return conn.initProcessReply(&out, hasSysAdminCap) +} + +// Process the FUSE_INIT reply from the FUSE server. +func (conn *connection) initProcessReply(out *linux.FUSEInitOut, hasSysAdminCap bool) error { + // No support for old major fuse versions. + if out.Major != linux.FUSE_KERNEL_VERSION { + conn.connInitError = true + + // Set the connection as initialized and unblock the blocked requests + // (i.e. return error for them). + conn.SetInitialized() + + return nil + } + + // Start processing the reply. + conn.connInitSuccess = true + conn.minor = out.Minor + + // No support for limits before minor version 13. + if out.Minor >= 13 { + conn.bgLock.Lock() + + if out.MaxBackground > 0 { + conn.maxBackground = out.MaxBackground + + if !hasSysAdminCap && + conn.maxBackground > MaxUserBackgroundRequest { + conn.maxBackground = MaxUserBackgroundRequest + } + } + + if out.CongestionThreshold > 0 { + conn.congestionThreshold = out.CongestionThreshold + + if !hasSysAdminCap && + conn.congestionThreshold > MaxUserCongestionThreshold { + conn.congestionThreshold = MaxUserCongestionThreshold + } + } + + conn.bgLock.Unlock() + } + + // No support for the following flags before minor version 6. + if out.Minor >= 6 { + conn.asyncRead = out.Flags&linux.FUSE_ASYNC_READ != 0 + conn.bigWrites = out.Flags&linux.FUSE_BIG_WRITES != 0 + conn.dontMask = out.Flags&linux.FUSE_DONT_MASK != 0 + conn.writebackCache = out.Flags&linux.FUSE_WRITEBACK_CACHE != 0 + conn.cacheSymlinks = out.Flags&linux.FUSE_CACHE_SYMLINKS != 0 + conn.abortErr = out.Flags&linux.FUSE_ABORT_ERROR != 0 + + // TODO(gvisor.dev/issue/3195): figure out how to use TimeGran (0 < TimeGran <= fuseMaxTimeGranNs). + + if out.Flags&linux.FUSE_MAX_PAGES != 0 { + maxPages := out.MaxPages + if maxPages < 1 { + maxPages = 1 + } + if maxPages > fuseMaxMaxPages { + maxPages = fuseMaxMaxPages + } + conn.maxPages = maxPages + } + } + + // No support for negotiating MaxWrite before minor version 5. + if out.Minor >= 5 { + conn.maxWrite = out.MaxWrite + } else { + conn.maxWrite = fuseMinMaxWrite + } + if conn.maxWrite < fuseMinMaxWrite { + conn.maxWrite = fuseMinMaxWrite + } + + // Set connection as initialized and unblock the requests + // issued before init. + conn.SetInitialized() + + return nil +} diff --git a/pkg/sentry/fsimpl/fuse/register.go b/pkg/sentry/fsimpl/fuse/register.go new file mode 100644 index 000000000..b5b581152 --- /dev/null +++ b/pkg/sentry/fsimpl/fuse/register.go @@ -0,0 +1,42 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package fuse + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/fsimpl/devtmpfs" + "gvisor.dev/gvisor/pkg/sentry/vfs" +) + +// Register registers the FUSE device with vfsObj. +func Register(vfsObj *vfs.VirtualFilesystem) error { + if err := vfsObj.RegisterDevice(vfs.CharDevice, linux.MISC_MAJOR, fuseDevMinor, fuseDevice{}, &vfs.RegisterDeviceOptions{ + GroupName: "misc", + }); err != nil { + return err + } + + return nil +} + +// CreateDevtmpfsFile creates a device special file in devtmpfs. +func CreateDevtmpfsFile(ctx context.Context, dev *devtmpfs.Accessor) error { + if err := dev.CreateDeviceFile(ctx, "fuse", vfs.CharDevice, linux.MISC_MAJOR, fuseDevMinor, 0666 /* mode */); err != nil { + return err + } + + return nil +} diff --git a/pkg/sentry/fsimpl/gofer/BUILD b/pkg/sentry/fsimpl/gofer/BUILD index 67e916525..4a800dcf9 100644 --- a/pkg/sentry/fsimpl/gofer/BUILD +++ b/pkg/sentry/fsimpl/gofer/BUILD @@ -35,6 +35,7 @@ go_library( "fstree.go", "gofer.go", "handle.go", + "host_named_pipe.go", "p9file.go", "regular_file.go", "socket.go", @@ -47,11 +48,13 @@ go_library( "//pkg/abi/linux", "//pkg/context", "//pkg/fd", + "//pkg/fdnotifier", "//pkg/fspath", "//pkg/log", "//pkg/p9", "//pkg/safemem", "//pkg/sentry/fs/fsutil", + "//pkg/sentry/fs/lock", "//pkg/sentry/fsimpl/host", "//pkg/sentry/hostfd", "//pkg/sentry/kernel", @@ -71,6 +74,7 @@ go_library( "//pkg/unet", "//pkg/usermem", "//pkg/waiter", + "@org_golang_x_sys//unix:go_default_library", ], ) diff --git a/pkg/sentry/fsimpl/gofer/directory.go b/pkg/sentry/fsimpl/gofer/directory.go index b98218753..8c7c8e1b3 100644 --- a/pkg/sentry/fsimpl/gofer/directory.go +++ b/pkg/sentry/fsimpl/gofer/directory.go @@ -85,6 +85,7 @@ func (d *dentry) createSyntheticChildLocked(opts *createSyntheticOpts) { d2 := &dentry{ refs: 1, // held by d fs: d.fs, + ino: d.fs.nextSyntheticIno(), mode: uint32(opts.mode), uid: uint32(opts.kuid), gid: uint32(opts.kgid), @@ -138,6 +139,7 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba fd.dirents = ds } + d.InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent) if d.cachedMetadataAuthoritative() { d.touchAtime(fd.vfsfd.Mount()) } @@ -183,13 +185,13 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) { { Name: ".", Type: linux.DT_DIR, - Ino: d.ino, + Ino: uint64(d.ino), NextOff: 1, }, { Name: "..", Type: uint8(atomic.LoadUint32(&parent.mode) >> 12), - Ino: parent.ino, + Ino: uint64(parent.ino), NextOff: 2, }, } @@ -225,7 +227,7 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) { } dirent := vfs.Dirent{ Name: p9d.Name, - Ino: p9d.QID.Path, + Ino: uint64(inoFromPath(p9d.QID.Path)), NextOff: int64(len(dirents) + 1), } // p9 does not expose 9P2000.U's DMDEVICE, DMNAMEDPIPE, or @@ -258,7 +260,7 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) { dirents = append(dirents, vfs.Dirent{ Name: child.name, Type: uint8(atomic.LoadUint32(&child.mode) >> 12), - Ino: child.ino, + Ino: uint64(child.ino), NextOff: int64(len(dirents) + 1), }) } @@ -299,3 +301,8 @@ func (fd *directoryFD) Seek(ctx context.Context, offset int64, whence int32) (in return 0, syserror.EINVAL } } + +// Sync implements vfs.FileDescriptionImpl.Sync. +func (fd *directoryFD) Sync(ctx context.Context) error { + return fd.dentry().handle.sync(ctx) +} diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index 7f2181216..00e3c99cd 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -16,6 +16,7 @@ package gofer import ( "sync" + "sync/atomic" "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" @@ -118,7 +119,7 @@ func putDentrySlice(ds *[]*dentry) { // must be up to date. // // Postconditions: The returned dentry's cached metadata is up to date. -func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, ds **[]*dentry) (*dentry, error) { +func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, mayFollowSymlinks bool, ds **[]*dentry) (*dentry, error) { if !d.isDir() { return nil, syserror.ENOTDIR } @@ -149,11 +150,9 @@ afterSymlink: return nil, err } if d != d.parent && !d.cachedMetadataAuthoritative() { - _, attrMask, attr, err := d.parent.file.getAttr(ctx, dentryAttrMask()) - if err != nil { + if err := d.parent.updateFromGetattr(ctx); err != nil { return nil, err } - d.parent.updateFromP9Attrs(attrMask, &attr) } rp.Advance() return d.parent, nil @@ -168,7 +167,7 @@ afterSymlink: if err := rp.CheckMount(&child.vfsd); err != nil { return nil, err } - if child.isSymlink() && rp.ShouldFollowSymlink() { + if child.isSymlink() && mayFollowSymlinks && rp.ShouldFollowSymlink() { target, err := child.readlink(ctx, rp.Mount()) if err != nil { return nil, err @@ -208,18 +207,28 @@ func (fs *filesystem) getChildLocked(ctx context.Context, vfsObj *vfs.VirtualFil // Preconditions: As for getChildLocked. !parent.isSynthetic(). func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *dentry, name string, child *dentry, ds **[]*dentry) (*dentry, error) { + if child != nil { + // Need to lock child.metadataMu because we might be updating child + // metadata. We need to hold the lock *before* getting metadata from the + // server and release it after updating local metadata. + child.metadataMu.Lock() + } qid, file, attrMask, attr, err := parent.file.walkGetAttrOne(ctx, name) if err != nil && err != syserror.ENOENT { + if child != nil { + child.metadataMu.Unlock() + } return nil, err } if child != nil { - if !file.isNil() && qid.Path == child.ino { - // The file at this path hasn't changed. Just update cached - // metadata. + if !file.isNil() && inoFromPath(qid.Path) == child.ino { + // The file at this path hasn't changed. Just update cached metadata. file.close(ctx) - child.updateFromP9Attrs(attrMask, &attr) + child.updateFromP9AttrsLocked(attrMask, &attr) + child.metadataMu.Unlock() return child, nil } + child.metadataMu.Unlock() if file.isNil() && child.isSynthetic() { // We have a synthetic file, and no remote file has arisen to // replace it. @@ -275,7 +284,7 @@ func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir func (fs *filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, ds **[]*dentry) (*dentry, error) { for !rp.Final() { d.dirMu.Lock() - next, err := fs.stepLocked(ctx, rp, d, ds) + next, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds) d.dirMu.Unlock() if err != nil { return nil, err @@ -301,7 +310,7 @@ func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath, } for !rp.Done() { d.dirMu.Lock() - next, err := fs.stepLocked(ctx, rp, d, ds) + next, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds) d.dirMu.Unlock() if err != nil { return nil, err @@ -371,17 +380,33 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir } parent.touchCMtime() parent.dirents = nil + ev := linux.IN_CREATE + if dir { + ev |= linux.IN_ISDIR + } + parent.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */) return nil } if fs.opts.interop == InteropModeShared { - // The existence of a dentry at name would be inconclusive because the - // file it represents may have been deleted from the remote filesystem, - // so we would need to make an RPC to revalidate the dentry. Just - // attempt the file creation RPC instead. If a file does exist, the RPC - // will fail with EEXIST like we would have. If the RPC succeeds, and a - // stale dentry exists, the dentry will fail revalidation next time - // it's used. - return createInRemoteDir(parent, name) + if child := parent.children[name]; child != nil && child.isSynthetic() { + return syserror.EEXIST + } + // The existence of a non-synthetic dentry at name would be inconclusive + // because the file it represents may have been deleted from the remote + // filesystem, so we would need to make an RPC to revalidate the dentry. + // Just attempt the file creation RPC instead. If a file does exist, the + // RPC will fail with EEXIST like we would have. If the RPC succeeds, and a + // stale dentry exists, the dentry will fail revalidation next time it's + // used. + if err := createInRemoteDir(parent, name); err != nil { + return err + } + ev := linux.IN_CREATE + if dir { + ev |= linux.IN_ISDIR + } + parent.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */) + return nil } if child := parent.children[name]; child != nil { return syserror.EEXIST @@ -397,6 +422,11 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir } parent.touchCMtime() parent.dirents = nil + ev := linux.IN_CREATE + if dir { + ev |= linux.IN_ISDIR + } + parent.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */) return nil } @@ -443,21 +473,61 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b defer mntns.DecRef() parent.dirMu.Lock() defer parent.dirMu.Unlock() + child, ok := parent.children[name] if ok && child == nil { return syserror.ENOENT } - // We only need a dentry representing the file at name if it can be a mount - // point. If child is nil, then it can't be a mount point. If child is - // non-nil but stale, the actual file can't be a mount point either; we - // detect this case by just speculatively calling PrepareDeleteDentry and - // only revalidating the dentry if that fails (indicating that the existing - // dentry is a mount point). + + sticky := atomic.LoadUint32(&parent.mode)&linux.ModeSticky != 0 + if sticky { + if !ok { + // If the sticky bit is set, we need to retrieve the child to determine + // whether removing it is allowed. + child, err = fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds) + if err != nil { + return err + } + } else if child != nil && !child.cachedMetadataAuthoritative() { + // Make sure the dentry representing the file at name is up to date + // before examining its metadata. + child, err = fs.revalidateChildLocked(ctx, vfsObj, parent, name, child, &ds) + if err != nil { + return err + } + } + if err := parent.mayDelete(rp.Credentials(), child); err != nil { + return err + } + } + + // If a child dentry exists, prepare to delete it. This should fail if it is + // a mount point. We detect mount points by speculatively calling + // PrepareDeleteDentry, which fails if child is a mount point. However, we + // may need to revalidate the file in this case to make sure that it has not + // been deleted or replaced on the remote fs, in which case the mount point + // will have disappeared. If calling PrepareDeleteDentry fails again on the + // up-to-date dentry, we can be sure that it is a mount point. + // + // Also note that if child is nil, then it can't be a mount point. if child != nil { + // Hold child.dirMu so we can check child.children and + // child.syntheticChildren. We don't access these fields until a bit later, + // but locking child.dirMu after calling vfs.PrepareDeleteDentry() would + // create an inconsistent lock ordering between dentry.dirMu and + // vfs.Dentry.mu (in the VFS lock order, it would make dentry.dirMu both "a + // FilesystemImpl lock" and "a lock acquired by a FilesystemImpl between + // PrepareDeleteDentry and CommitDeleteDentry). To avoid this, lock + // child.dirMu before calling PrepareDeleteDentry. child.dirMu.Lock() defer child.dirMu.Unlock() if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil { - if parent.cachedMetadataAuthoritative() { + // We can skip revalidation in several cases: + // - We are not in InteropModeShared + // - The parent directory is synthetic, in which case the child must also + // be synthetic + // - We already updated the child during the sticky bit check above + if parent.cachedMetadataAuthoritative() || sticky { return err } child, err = fs.revalidateChildLocked(ctx, vfsObj, parent, name, child, &ds) @@ -518,7 +588,7 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b if child == nil { return syserror.ENOENT } - } else { + } else if child == nil || !child.isSynthetic() { err = parent.file.unlinkAt(ctx, name, flags) if err != nil { if child != nil { @@ -527,6 +597,18 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b return err } } + + // Generate inotify events for rmdir or unlink. + if dir { + parent.watches.Notify(name, linux.IN_DELETE|linux.IN_ISDIR, 0, vfs.InodeEvent, true /* unlinked */) + } else { + var cw *vfs.Watches + if child != nil { + cw = &child.watches + } + vfs.InotifyRemoveChild(cw, &parent.watches, name) + } + if child != nil { vfsObj.CommitDeleteDentry(&child.vfsd) child.setDeleted() @@ -754,25 +836,27 @@ afterTrailingSymlink: } // Determine whether or not we need to create a file. parent.dirMu.Lock() - child, err := fs.stepLocked(ctx, rp, parent, &ds) + child, err := fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds) if err == syserror.ENOENT && mayCreate { if parent.isSynthetic() { parent.dirMu.Unlock() return nil, syserror.EPERM } - fd, err := parent.createAndOpenChildLocked(ctx, rp, &opts) + fd, err := parent.createAndOpenChildLocked(ctx, rp, &opts, &ds) parent.dirMu.Unlock() return fd, err } + parent.dirMu.Unlock() if err != nil { - parent.dirMu.Unlock() return nil, err } - // Open existing child or follow symlink. - parent.dirMu.Unlock() if mustCreate { return nil, syserror.EEXIST } + if !child.isDir() && rp.MustBeDir() { + return nil, syserror.ENOTDIR + } + // Open existing child or follow symlink. if child.isSymlink() && rp.ShouldFollowSymlink() { target, err := child.readlink(ctx, rp.Mount()) if err != nil { @@ -793,20 +877,32 @@ func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vf if err := d.checkPermissions(rp.Credentials(), ats); err != nil { return nil, err } + + trunc := opts.Flags&linux.O_TRUNC != 0 && d.fileType() == linux.S_IFREG + if trunc { + // Lock metadataMu *while* we open a regular file with O_TRUNC because + // open(2) will change the file size on server. + d.metadataMu.Lock() + defer d.metadataMu.Unlock() + } + + var vfd *vfs.FileDescription + var err error mnt := rp.Mount() switch d.fileType() { case linux.S_IFREG: if !d.fs.opts.regularFilesUseSpecialFileFD { - if err := d.ensureSharedHandle(ctx, ats&vfs.MayRead != 0, ats&vfs.MayWrite != 0, opts.Flags&linux.O_TRUNC != 0); err != nil { + if err := d.ensureSharedHandle(ctx, ats&vfs.MayRead != 0, ats&vfs.MayWrite != 0, trunc); err != nil { return nil, err } fd := ®ularFileFD{} + fd.LockFD.Init(&d.locks) if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{ AllowDirectIO: true, }); err != nil { return nil, err } - return &fd.vfsfd, nil + vfd = &fd.vfsfd } case linux.S_IFDIR: // Can't open directories with O_CREAT. @@ -826,6 +922,7 @@ func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vf } } fd := &directoryFD{} + fd.LockFD.Init(&d.locks) if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } @@ -842,10 +939,28 @@ func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vf } case linux.S_IFIFO: if d.isSynthetic() { - return d.pipe.Open(ctx, mnt, &d.vfsd, opts.Flags) + return d.pipe.Open(ctx, mnt, &d.vfsd, opts.Flags, &d.locks) + } + } + + if vfd == nil { + if vfd, err = d.openSpecialFileLocked(ctx, mnt, opts); err != nil { + return nil, err + } + } + + if trunc { + // If no errors occured so far then update file size in memory. This + // step is required even if !d.cachedMetadataAuthoritative() because + // d.mappings has to be updated. + // d.metadataMu has already been acquired if trunc == true. + d.updateFileSizeLocked(0) + + if d.cachedMetadataAuthoritative() { + d.touchCMtimeLocked() } } - return d.openSpecialFileLocked(ctx, mnt, opts) + return vfd, err } func (d *dentry) connectSocketLocked(ctx context.Context, opts *vfs.OpenOptions) (*vfs.FileDescription, error) { @@ -873,19 +988,37 @@ func (d *dentry) openSpecialFileLocked(ctx context.Context, mnt *vfs.Mount, opts if opts.Flags&linux.O_DIRECT != 0 { return nil, syserror.EINVAL } - h, err := openHandle(ctx, d.file, ats&vfs.MayRead != 0, ats&vfs.MayWrite != 0, opts.Flags&linux.O_TRUNC != 0) + // We assume that the server silently inserts O_NONBLOCK in the open flags + // for all named pipes (because all existing gofers do this). + // + // NOTE(b/133875563): This makes named pipe opens racy, because the + // mechanisms for translating nonblocking to blocking opens can only detect + // the instantaneous presence of a peer holding the other end of the pipe + // open, not whether the pipe was *previously* opened by a peer that has + // since closed its end. + isBlockingOpenOfNamedPipe := d.fileType() == linux.S_IFIFO && opts.Flags&linux.O_NONBLOCK == 0 +retry: + h, err := openHandle(ctx, d.file, ats.MayRead(), ats.MayWrite(), opts.Flags&linux.O_TRUNC != 0) if err != nil { + if isBlockingOpenOfNamedPipe && ats == vfs.MayWrite && err == syserror.ENXIO { + // An attempt to open a named pipe with O_WRONLY|O_NONBLOCK fails + // with ENXIO if opening the same named pipe with O_WRONLY would + // block because there are no readers of the pipe. + if err := sleepBetweenNamedPipeOpenChecks(ctx); err != nil { + return nil, err + } + goto retry + } return nil, err } - seekable := d.fileType() == linux.S_IFREG - fd := &specialFileFD{ - handle: h, - seekable: seekable, + if isBlockingOpenOfNamedPipe && ats == vfs.MayRead && h.fd >= 0 { + if err := blockUntilNonblockingPipeHasWriter(ctx, h.fd); err != nil { + h.close(ctx) + return nil, err + } } - if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{ - DenyPRead: !seekable, - DenyPWrite: !seekable, - }); err != nil { + fd, err := newSpecialFileFD(h, mnt, d, &d.locks, opts.Flags) + if err != nil { h.close(ctx) return nil, err } @@ -894,7 +1027,7 @@ func (d *dentry) openSpecialFileLocked(ctx context.Context, mnt *vfs.Mount, opts // Preconditions: d.fs.renameMu must be locked. d.dirMu must be locked. // !d.isSynthetic(). -func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions) (*vfs.FileDescription, error) { +func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions, ds **[]*dentry) (*vfs.FileDescription, error) { if err := d.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil { return nil, err } @@ -919,7 +1052,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving // Filter file creation flags and O_LARGEFILE out; the create RPC already // has the semantics of O_CREAT|O_EXCL, while some servers will choke on // O_LARGEFILE. - createFlags := p9.OpenFlags(opts.Flags &^ (linux.O_CREAT | linux.O_EXCL | linux.O_NOCTTY | linux.O_TRUNC | linux.O_LARGEFILE)) + createFlags := p9.OpenFlags(opts.Flags &^ (vfs.FileCreationFlags | linux.O_LARGEFILE)) fdobj, openFile, createQID, _, err := dirfile.create(ctx, name, createFlags, (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID)) if err != nil { dirfile.close(ctx) @@ -947,6 +1080,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } return nil, err } + *ds = appendDentry(*ds, child) // Incorporate the fid that was opened by lcreate. useRegularFileFD := child.fileType() == linux.S_IFREG && !d.fs.opts.regularFilesUseSpecialFileFD if useRegularFileFD { @@ -959,10 +1093,6 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving child.handleWritable = vfs.MayWriteFileWithOpenFlags(opts.Flags) child.handleMu.Unlock() } - // Take a reference on the new dentry to be held by the new file - // description. (This reference also means that the new dentry is not - // eligible for caching yet, so we don't need to append to a dentry slice.) - child.refs = 1 // Insert the dentry into the tree. d.cacheNewChildLocked(child, name) if d.cachedMetadataAuthoritative() { @@ -974,6 +1104,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving var childVFSFD *vfs.FileDescription if useRegularFileFD { fd := ®ularFileFD{} + fd.LockFD.Init(&child.locks) if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &child.vfsd, &vfs.FileDescriptionOptions{ AllowDirectIO: true, }); err != nil { @@ -981,26 +1112,21 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } childVFSFD = &fd.vfsfd } else { - seekable := child.fileType() == linux.S_IFREG - fd := &specialFileFD{ - handle: handle{ - file: openFile, - fd: -1, - }, - seekable: seekable, + h := handle{ + file: openFile, + fd: -1, } if fdobj != nil { - fd.handle.fd = int32(fdobj.Release()) + h.fd = int32(fdobj.Release()) } - if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &child.vfsd, &vfs.FileDescriptionOptions{ - DenyPRead: !seekable, - DenyPWrite: !seekable, - }); err != nil { - fd.handle.close(ctx) + fd, err := newSpecialFileFD(h, mnt, child, &d.locks, opts.Flags) + if err != nil { + h.close(ctx) return nil, err } childVFSFD = &fd.vfsfd } + d.watches.Notify(name, linux.IN_CREATE, 0, vfs.PathEvent, false /* unlinked */) return childVFSFD, nil } @@ -1052,7 +1178,8 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa return err } } - if err := oldParent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil { + creds := rp.Credentials() + if err := oldParent.checkPermissions(creds, vfs.MayWrite|vfs.MayExec); err != nil { return err } vfsObj := rp.VirtualFilesystem() @@ -1067,12 +1194,15 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa if renamed == nil { return syserror.ENOENT } + if err := oldParent.mayDelete(creds, renamed); err != nil { + return err + } if renamed.isDir() { if renamed == newParent || genericIsAncestorDentry(renamed, newParent) { return syserror.EINVAL } if oldParent != newParent { - if err := renamed.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil { + if err := renamed.checkPermissions(creds, vfs.MayWrite); err != nil { return err } } @@ -1083,7 +1213,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa } if oldParent != newParent { - if err := newParent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil { + if err := newParent.checkPermissions(creds, vfs.MayWrite|vfs.MayExec); err != nil { return err } newParent.dirMu.Lock() @@ -1181,10 +1311,12 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa if newParent.cachedMetadataAuthoritative() { newParent.dirents = nil newParent.touchCMtime() - if renamed.isDir() { + if renamed.isDir() && (replaced == nil || !replaced.isDir()) { + // Increase the link count if we did not replace another directory. newParent.incLinks() } } + vfs.InotifyRename(ctx, &renamed.watches, &oldParent.watches, &newParent.watches, oldName, newName, renamed.isDir()) return nil } @@ -1197,12 +1329,21 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) return err } - return d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount()) + if err := d.setStat(ctx, rp.Credentials(), &opts, rp.Mount()); err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) + return err + } + fs.renameMuRUnlockAndCheckCaching(&ds) + + if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { + d.InotifyWithParent(ev, 0, vfs.InodeEvent) + } + return nil } // StatAt implements vfs.FilesystemImpl.StatAt. @@ -1326,24 +1467,38 @@ func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) return err } - return d.setxattr(ctx, rp.Credentials(), &opts) + if err := d.setxattr(ctx, rp.Credentials(), &opts); err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) + return err + } + fs.renameMuRUnlockAndCheckCaching(&ds) + + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt. func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) return err } - return d.removexattr(ctx, rp.Credentials(), name) + if err := d.removexattr(ctx, rp.Credentials(), name); err != nil { + fs.renameMuRUnlockAndCheckCaching(&ds) + return err + } + fs.renameMuRUnlockAndCheckCaching(&ds) + + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // PrependPath implements vfs.FilesystemImpl.PrependPath. @@ -1352,3 +1507,7 @@ func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDe defer fs.renameMu.RUnlock() return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b) } + +func (fs *filesystem) nextSyntheticIno() inodeNumber { + return inodeNumber(atomic.AddUint64(&fs.syntheticSeq, 1) | syntheticInoMask) +} diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index 6295f6b54..e20de84b5 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -45,6 +45,7 @@ import ( "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/p9" "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/kernel/pipe" ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time" @@ -84,12 +85,6 @@ type filesystem struct { // devMinor is the filesystem's minor device number. devMinor is immutable. devMinor uint32 - // uid and gid are the effective KUID and KGID of the filesystem's creator, - // and are used as the owner and group for files that don't specify one. - // uid and gid are immutable. - uid auth.KUID - gid auth.KGID - // renameMu serves two purposes: // // - It synchronizes path resolution with renaming initiated by this @@ -115,6 +110,26 @@ type filesystem struct { syncMu sync.Mutex syncableDentries map[*dentry]struct{} specialFileFDs map[*specialFileFD]struct{} + + // syntheticSeq stores a counter to used to generate unique inodeNumber for + // synthetic dentries. + syntheticSeq uint64 +} + +// inodeNumber represents inode number reported in Dirent.Ino. For regular +// dentries, it comes from QID.Path from the 9P server. Synthetic dentries +// have have their inodeNumber generated sequentially, with the MSB reserved to +// prevent conflicts with regular dentries. +type inodeNumber uint64 + +// Reserve MSB for synthetic mounts. +const syntheticInoMask = uint64(1) << 63 + +func inoFromPath(path uint64) inodeNumber { + if path&syntheticInoMask != 0 { + log.Warningf("Dropping MSB from ino, collision is possible. Original: %d, new: %d", path, path&^syntheticInoMask) + } + return inodeNumber(path &^ syntheticInoMask) } type filesystemOptions struct { @@ -122,6 +137,8 @@ type filesystemOptions struct { fd int aname string interop InteropMode // derived from the "cache" mount option + dfltuid auth.KUID + dfltgid auth.KGID msize uint32 version string @@ -230,6 +247,15 @@ type InternalFilesystemOptions struct { OpenSocketsByConnecting bool } +// _V9FS_DEFUID and _V9FS_DEFGID (from Linux's fs/9p/v9fs.h) are the default +// UIDs and GIDs used for files that do not provide a specific owner or group +// respectively. +const ( + // uint32(-2) doesn't work in Go. + _V9FS_DEFUID = auth.KUID(4294967294) + _V9FS_DEFGID = auth.KGID(4294967294) +) + // Name implements vfs.FilesystemType.Name. func (FilesystemType) Name() string { return Name @@ -315,6 +341,31 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt } } + // Parse the default UID and GID. + fsopts.dfltuid = _V9FS_DEFUID + if dfltuidstr, ok := mopts["dfltuid"]; ok { + delete(mopts, "dfltuid") + dfltuid, err := strconv.ParseUint(dfltuidstr, 10, 32) + if err != nil { + ctx.Warningf("gofer.FilesystemType.GetFilesystem: invalid default UID: dfltuid=%s", dfltuidstr) + return nil, nil, syserror.EINVAL + } + // In Linux, dfltuid is interpreted as a UID and is converted to a KUID + // in the caller's user namespace, but goferfs isn't + // application-mountable. + fsopts.dfltuid = auth.KUID(dfltuid) + } + fsopts.dfltgid = _V9FS_DEFGID + if dfltgidstr, ok := mopts["dfltgid"]; ok { + delete(mopts, "dfltgid") + dfltgid, err := strconv.ParseUint(dfltgidstr, 10, 32) + if err != nil { + ctx.Warningf("gofer.FilesystemType.GetFilesystem: invalid default UID: dfltgid=%s", dfltgidstr) + return nil, nil, syserror.EINVAL + } + fsopts.dfltgid = auth.KGID(dfltgid) + } + // Parse the 9P message size. fsopts.msize = 1024 * 1024 // 1M, tested to give good enough performance up to 64M if msizestr, ok := mopts["msize"]; ok { @@ -422,8 +473,6 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt client: client, clock: ktime.RealtimeClockFromContext(ctx), devMinor: devMinor, - uid: creds.EffectiveKUID, - gid: creds.EffectiveKGID, syncableDentries: make(map[*dentry]struct{}), specialFileFDs: make(map[*specialFileFD]struct{}), } @@ -553,21 +602,27 @@ type dentry struct { // returned by the server. dirents is protected by dirMu. dirents []vfs.Dirent - // Cached metadata; protected by metadataMu and accessed using atomic - // memory operations unless otherwise specified. + // Cached metadata; protected by metadataMu. + // To access: + // - In situations where consistency is not required (like stat), these + // can be accessed using atomic operations only (without locking). + // - Lock metadataMu and can access without atomic operations. + // To mutate: + // - Lock metadataMu and use atomic operations to update because we might + // have atomic readers that don't hold the lock. metadataMu sync.Mutex - ino uint64 // immutable - mode uint32 // type is immutable, perms are mutable - uid uint32 // auth.KUID, but stored as raw uint32 for sync/atomic - gid uint32 // auth.KGID, but ... - blockSize uint32 // 0 if unknown + ino inodeNumber // immutable + mode uint32 // type is immutable, perms are mutable + uid uint32 // auth.KUID, but stored as raw uint32 for sync/atomic + gid uint32 // auth.KGID, but ... + blockSize uint32 // 0 if unknown // Timestamps, all nsecs from the Unix epoch. atime int64 mtime int64 ctime int64 btime int64 // File size, protected by both metadataMu and dataMu (i.e. both must be - // locked to mutate it). + // locked to mutate it; locking either is sufficient to access it). size uint64 // nlink counts the number of hard links to this dentry. It's updated and @@ -634,6 +689,11 @@ type dentry struct { // If this dentry represents a synthetic named pipe, pipe is the pipe // endpoint bound to this file. pipe *pipe.VFSPipe + + locks vfs.FileLocks + + // Inotify watches for this dentry. + watches vfs.Watches } // dentryAttrMask returns a p9.AttrMask enabling all attributes used by the @@ -670,10 +730,10 @@ func (fs *filesystem) newDentry(ctx context.Context, file p9file, qid p9.QID, ma d := &dentry{ fs: fs, file: file, - ino: qid.Path, + ino: inoFromPath(qid.Path), mode: uint32(attr.Mode), - uid: uint32(fs.uid), - gid: uint32(fs.gid), + uid: uint32(fs.opts.dfltuid), + gid: uint32(fs.opts.dfltgid), blockSize: usermem.PageSize, handle: handle{ fd: -1, @@ -725,8 +785,8 @@ func (d *dentry) cachedMetadataAuthoritative() bool { // updateFromP9Attrs is called to update d's metadata after an update from the // remote filesystem. -func (d *dentry) updateFromP9Attrs(mask p9.AttrMask, attr *p9.Attr) { - d.metadataMu.Lock() +// Precondition: d.metadataMu must be locked. +func (d *dentry) updateFromP9AttrsLocked(mask p9.AttrMask, attr *p9.Attr) { if mask.Mode { if got, want := uint32(attr.Mode.FileType()), d.fileType(); got != want { d.metadataMu.Unlock() @@ -760,11 +820,8 @@ func (d *dentry) updateFromP9Attrs(mask p9.AttrMask, attr *p9.Attr) { atomic.StoreUint32(&d.nlink, uint32(attr.NLink)) } if mask.Size { - d.dataMu.Lock() - atomic.StoreUint64(&d.size, attr.Size) - d.dataMu.Unlock() + d.updateFileSizeLocked(attr.Size) } - d.metadataMu.Unlock() } // Preconditions: !d.isSynthetic() @@ -776,6 +833,10 @@ func (d *dentry) updateFromGetattr(ctx context.Context) error { file p9file handleMuRLocked bool ) + // d.metadataMu must be locked *before* we getAttr so that we do not end up + // updating stale attributes in d.updateFromP9AttrsLocked(). + d.metadataMu.Lock() + defer d.metadataMu.Unlock() d.handleMu.RLock() if !d.handle.file.isNil() { file = d.handle.file @@ -791,7 +852,7 @@ func (d *dentry) updateFromGetattr(ctx context.Context) error { if err != nil { return err } - d.updateFromP9Attrs(attrMask, &attr) + d.updateFromP9AttrsLocked(attrMask, &attr) return nil } @@ -803,10 +864,18 @@ func (d *dentry) statTo(stat *linux.Statx) { stat.Mask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_NLINK | linux.STATX_UID | linux.STATX_GID | linux.STATX_ATIME | linux.STATX_MTIME | linux.STATX_CTIME | linux.STATX_INO | linux.STATX_SIZE | linux.STATX_BLOCKS | linux.STATX_BTIME stat.Blksize = atomic.LoadUint32(&d.blockSize) stat.Nlink = atomic.LoadUint32(&d.nlink) + if stat.Nlink == 0 { + // The remote filesystem doesn't support link count; just make + // something up. This is consistent with Linux, where + // fs/inode.c:inode_init_always() initializes link count to 1, and + // fs/9p/vfs_inode_dotl.c:v9fs_stat2inode_dotl() doesn't touch it if + // it's not provided by the remote filesystem. + stat.Nlink = 1 + } stat.UID = atomic.LoadUint32(&d.uid) stat.GID = atomic.LoadUint32(&d.gid) stat.Mode = uint16(atomic.LoadUint32(&d.mode)) - stat.Ino = d.ino + stat.Ino = uint64(d.ino) stat.Size = atomic.LoadUint64(&d.size) // This is consistent with regularFileFD.Seek(), which treats regular files // as having no holes. @@ -819,7 +888,8 @@ func (d *dentry) statTo(stat *linux.Statx) { stat.DevMinor = d.fs.devMinor } -func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx, mnt *vfs.Mount) error { +func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs.SetStatOptions, mnt *vfs.Mount) error { + stat := &opts.Stat if stat.Mask == 0 { return nil } @@ -827,7 +897,7 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin return syserror.EPERM } mode := linux.FileMode(atomic.LoadUint32(&d.mode)) - if err := vfs.CheckSetStat(ctx, creds, stat, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil { + if err := vfs.CheckSetStat(ctx, creds, opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil { return err } if err := mnt.CheckBeginWrite(); err != nil { @@ -844,14 +914,14 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin // Prepare for truncate. if stat.Mask&linux.STATX_SIZE != 0 { - switch d.mode & linux.S_IFMT { - case linux.S_IFREG: + switch mode.FileType() { + case linux.ModeRegular: if !setLocalMtime { // Truncate updates mtime. setLocalMtime = true stat.Mtime.Nsec = linux.UTIME_NOW } - case linux.S_IFDIR: + case linux.ModeDirectory: return syserror.EISDIR default: return syserror.EINVAL @@ -860,8 +930,25 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin } d.metadataMu.Lock() defer d.metadataMu.Unlock() + if stat.Mask&linux.STATX_SIZE != 0 { + // The size needs to be changed even when + // !d.cachedMetadataAuthoritative() because d.mappings has to be + // updated. + d.updateFileSizeLocked(stat.Size) + } if !d.isSynthetic() { if stat.Mask != 0 { + if stat.Mask&linux.STATX_SIZE != 0 { + // Check whether to allow a truncate request to be made. + switch d.mode & linux.S_IFMT { + case linux.S_IFREG: + // Allow. + case linux.S_IFDIR: + return syserror.EISDIR + default: + return syserror.EINVAL + } + } if err := d.file.setAttr(ctx, p9.SetAttrMask{ Permissions: stat.Mask&linux.STATX_MODE != 0, UID: stat.Mask&linux.STATX_UID != 0, @@ -908,6 +995,8 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin } else { atomic.StoreInt64(&d.atime, dentryTimestampFromStatx(stat.Atime)) } + // Restore mask bits that we cleared earlier. + stat.Mask |= linux.STATX_ATIME } if setLocalMtime { if stat.Mtime.Nsec == linux.UTIME_NOW { @@ -915,48 +1004,56 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin } else { atomic.StoreInt64(&d.mtime, dentryTimestampFromStatx(stat.Mtime)) } + // Restore mask bits that we cleared earlier. + stat.Mask |= linux.STATX_MTIME } atomic.StoreInt64(&d.ctime, now) - if stat.Mask&linux.STATX_SIZE != 0 { + return nil +} + +// Preconditions: d.metadataMu must be locked. +func (d *dentry) updateFileSizeLocked(newSize uint64) { + d.dataMu.Lock() + oldSize := d.size + atomic.StoreUint64(&d.size, newSize) + // d.dataMu must be unlocked to lock d.mapsMu and invalidate mappings + // below. This allows concurrent calls to Read/Translate/etc. These + // functions synchronize with truncation by refusing to use cache + // contents beyond the new d.size. (We are still holding d.metadataMu, + // so we can't race with Write or another truncate.) + d.dataMu.Unlock() + if d.size < oldSize { + oldpgend, _ := usermem.PageRoundUp(oldSize) + newpgend, _ := usermem.PageRoundUp(d.size) + if oldpgend != newpgend { + d.mapsMu.Lock() + d.mappings.Invalidate(memmap.MappableRange{newpgend, oldpgend}, memmap.InvalidateOpts{ + // Compare Linux's mm/truncate.c:truncate_setsize() => + // truncate_pagecache() => + // mm/memory.c:unmap_mapping_range(evencows=1). + InvalidatePrivate: true, + }) + d.mapsMu.Unlock() + } + // We are now guaranteed that there are no translations of + // truncated pages, and can remove them from the cache. Since + // truncated pages have been removed from the remote file, they + // should be dropped without being written back. d.dataMu.Lock() - oldSize := d.size - d.size = stat.Size - // d.dataMu must be unlocked to lock d.mapsMu and invalidate mappings - // below. This allows concurrent calls to Read/Translate/etc. These - // functions synchronize with truncation by refusing to use cache - // contents beyond the new d.size. (We are still holding d.metadataMu, - // so we can't race with Write or another truncate.) + d.cache.Truncate(d.size, d.fs.mfp.MemoryFile()) + d.dirty.KeepClean(memmap.MappableRange{d.size, oldpgend}) d.dataMu.Unlock() - if d.size < oldSize { - oldpgend, _ := usermem.PageRoundUp(oldSize) - newpgend, _ := usermem.PageRoundUp(d.size) - if oldpgend != newpgend { - d.mapsMu.Lock() - d.mappings.Invalidate(memmap.MappableRange{newpgend, oldpgend}, memmap.InvalidateOpts{ - // Compare Linux's mm/truncate.c:truncate_setsize() => - // truncate_pagecache() => - // mm/memory.c:unmap_mapping_range(evencows=1). - InvalidatePrivate: true, - }) - d.mapsMu.Unlock() - } - // We are now guaranteed that there are no translations of - // truncated pages, and can remove them from the cache. Since - // truncated pages have been removed from the remote file, they - // should be dropped without being written back. - d.dataMu.Lock() - d.cache.Truncate(d.size, d.fs.mfp.MemoryFile()) - d.dirty.KeepClean(memmap.MappableRange{d.size, oldpgend}) - d.dataMu.Unlock() - } } - return nil } func (d *dentry) checkPermissions(creds *auth.Credentials, ats vfs.AccessTypes) error { return vfs.GenericCheckPermissions(creds, ats, linux.FileMode(atomic.LoadUint32(&d.mode)), auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))) } +func (d *dentry) mayDelete(creds *auth.Credentials, child *dentry) error { + return vfs.CheckDeleteSticky(creds, linux.FileMode(atomic.LoadUint32(&d.mode)), auth.KUID(atomic.LoadUint32(&child.uid))) +} + func dentryUIDFromP9UID(uid p9.UID) uint32 { if !uid.Ok() { return uint32(auth.OverflowUID) @@ -1011,6 +1108,37 @@ func (d *dentry) decRefLocked() { } } +// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. +func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) { + if d.isDir() { + events |= linux.IN_ISDIR + } + + d.fs.renameMu.RLock() + // The ordering below is important, Linux always notifies the parent first. + if d.parent != nil { + d.parent.watches.Notify(d.name, events, cookie, et, d.isDeleted()) + } + d.watches.Notify("", events, cookie, et, d.isDeleted()) + d.fs.renameMu.RUnlock() +} + +// Watches implements vfs.DentryImpl.Watches. +func (d *dentry) Watches() *vfs.Watches { + return &d.watches +} + +// OnZeroWatches implements vfs.DentryImpl.OnZeroWatches. +// +// If no watches are left on this dentry and it has no references, cache it. +func (d *dentry) OnZeroWatches() { + if atomic.LoadInt64(&d.refs) == 0 { + d.fs.renameMu.Lock() + d.checkCachingLocked() + d.fs.renameMu.Unlock() + } +} + // checkCachingLocked should be called after d's reference count becomes 0 or it // becomes disowned. // @@ -1042,6 +1170,9 @@ func (d *dentry) checkCachingLocked() { // Deleted and invalidated dentries with zero references are no longer // reachable by path resolution and should be dropped immediately. if d.vfsd.IsDead() { + if d.isDeleted() { + d.watches.HandleDeletion() + } if d.cached { d.fs.cachedDentries.Remove(d) d.fs.cachedDentriesLen-- @@ -1050,6 +1181,14 @@ func (d *dentry) checkCachingLocked() { d.destroyLocked() return } + // If d still has inotify watches and it is not deleted or invalidated, we + // cannot cache it and allow it to be evicted. Otherwise, we will lose its + // watches, even if a new dentry is created for the same file in the future. + // Note that the size of d.watches cannot concurrently transition from zero + // to non-zero, because adding a watch requires holding a reference on d. + if d.watches.Size() > 0 { + return + } // If d is already cached, just move it to the front of the LRU. if d.cached { d.fs.cachedDentries.Remove(d) @@ -1155,7 +1294,7 @@ func (d *dentry) setDeleted() { // We only support xattrs prefixed with "user." (see b/148380782). Currently, // there is no need to expose any other xattrs through a gofer. func (d *dentry) listxattr(ctx context.Context, creds *auth.Credentials, size uint64) ([]string, error) { - if d.file.isNil() { + if d.file.isNil() || !d.userXattrSupported() { return nil, nil } xattrMap, err := d.file.listXattr(ctx, size) @@ -1181,6 +1320,9 @@ func (d *dentry) getxattr(ctx context.Context, creds *auth.Credentials, opts *vf if !strings.HasPrefix(opts.Name, linux.XATTR_USER_PREFIX) { return "", syserror.EOPNOTSUPP } + if !d.userXattrSupported() { + return "", syserror.ENODATA + } return d.file.getXattr(ctx, opts.Name, opts.Size) } @@ -1194,6 +1336,9 @@ func (d *dentry) setxattr(ctx context.Context, creds *auth.Credentials, opts *vf if !strings.HasPrefix(opts.Name, linux.XATTR_USER_PREFIX) { return syserror.EOPNOTSUPP } + if !d.userXattrSupported() { + return syserror.EPERM + } return d.file.setXattr(ctx, opts.Name, opts.Value, opts.Flags) } @@ -1207,10 +1352,20 @@ func (d *dentry) removexattr(ctx context.Context, creds *auth.Credentials, name if !strings.HasPrefix(name, linux.XATTR_USER_PREFIX) { return syserror.EOPNOTSUPP } + if !d.userXattrSupported() { + return syserror.EPERM + } return d.file.removeXattr(ctx, name) } -// Preconditions: !d.isSynthetic(). d.isRegularFile() || d.isDirectory(). +// Extended attributes in the user.* namespace are only supported for regular +// files and directories. +func (d *dentry) userXattrSupported() bool { + filetype := linux.FileMode(atomic.LoadUint32(&d.mode)).FileType() + return filetype == linux.ModeRegular || filetype == linux.ModeDirectory +} + +// Preconditions: !d.isSynthetic(). d.isRegularFile() || d.isDir(). func (d *dentry) ensureSharedHandle(ctx context.Context, read, write, trunc bool) error { // O_TRUNC unconditionally requires us to obtain a new handle (opened with // O_TRUNC). @@ -1302,23 +1457,21 @@ func (d *dentry) ensureSharedHandle(ctx context.Context, read, write, trunc bool } // incLinks increments link count. -// -// Preconditions: d.nlink != 0 && d.nlink < math.MaxUint32. func (d *dentry) incLinks() { - v := atomic.AddUint32(&d.nlink, 1) - if v < 2 { - panic(fmt.Sprintf("dentry.nlink is invalid (was 0 or overflowed): %d", v)) + if atomic.LoadUint32(&d.nlink) == 0 { + // The remote filesystem doesn't support link count. + return } + atomic.AddUint32(&d.nlink, 1) } // decLinks decrements link count. -// -// Preconditions: d.nlink > 1. func (d *dentry) decLinks() { - v := atomic.AddUint32(&d.nlink, ^uint32(0)) - if v == 0 { - panic(fmt.Sprintf("dentry.nlink must be greater than 0: %d", v)) + if atomic.LoadUint32(&d.nlink) == 0 { + // The remote filesystem doesn't support link count. + return } + atomic.AddUint32(&d.nlink, ^uint32(0)) } // fileDescription is embedded by gofer implementations of @@ -1326,6 +1479,9 @@ func (d *dentry) decLinks() { type fileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl + vfs.LockFD + + lockLogging sync.Once } func (fd *fileDescription) filesystem() *filesystem { @@ -1354,7 +1510,13 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu // SetStat implements vfs.FileDescriptionImpl.SetStat. func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error { - return fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts.Stat, fd.vfsfd.Mount()) + if err := fd.dentry().setStat(ctx, auth.CredentialsFromContext(ctx), &opts, fd.vfsfd.Mount()); err != nil { + return err + } + if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { + fd.dentry().InotifyWithParent(ev, 0, vfs.InodeEvent) + } + return nil } // Listxattr implements vfs.FileDescriptionImpl.Listxattr. @@ -1369,10 +1531,41 @@ func (fd *fileDescription) Getxattr(ctx context.Context, opts vfs.GetxattrOption // Setxattr implements vfs.FileDescriptionImpl.Setxattr. func (fd *fileDescription) Setxattr(ctx context.Context, opts vfs.SetxattrOptions) error { - return fd.dentry().setxattr(ctx, auth.CredentialsFromContext(ctx), &opts) + d := fd.dentry() + if err := d.setxattr(ctx, auth.CredentialsFromContext(ctx), &opts); err != nil { + return err + } + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // Removexattr implements vfs.FileDescriptionImpl.Removexattr. func (fd *fileDescription) Removexattr(ctx context.Context, name string) error { - return fd.dentry().removexattr(ctx, auth.CredentialsFromContext(ctx), name) + d := fd.dentry() + if err := d.removexattr(ctx, auth.CredentialsFromContext(ctx), name); err != nil { + return err + } + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil +} + +// LockBSD implements vfs.FileDescriptionImpl.LockBSD. +func (fd *fileDescription) LockBSD(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, block fslock.Blocker) error { + fd.lockLogging.Do(func() { + log.Infof("File lock using gofer file handled internally.") + }) + return fd.LockFD.LockBSD(ctx, uid, t, block) +} + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *fileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + fd.lockLogging.Do(func() { + log.Infof("Range lock using gofer file handled internally.") + }) + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *fileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) } diff --git a/pkg/sentry/fsimpl/gofer/handle.go b/pkg/sentry/fsimpl/gofer/handle.go index 724a3f1f7..8792ca4f2 100644 --- a/pkg/sentry/fsimpl/gofer/handle.go +++ b/pkg/sentry/fsimpl/gofer/handle.go @@ -126,11 +126,16 @@ func (h *handle) writeFromBlocksAt(ctx context.Context, srcs safemem.BlockSeq, o } func (h *handle) sync(ctx context.Context) error { + // Handle most common case first. if h.fd >= 0 { ctx.UninterruptibleSleepStart(false) err := syscall.Fsync(int(h.fd)) ctx.UninterruptibleSleepFinish(false) return err } + if h.file.isNil() { + // File hasn't been touched, there is nothing to sync. + return nil + } return h.file.fsync(ctx) } diff --git a/pkg/sentry/fsimpl/gofer/host_named_pipe.go b/pkg/sentry/fsimpl/gofer/host_named_pipe.go new file mode 100644 index 000000000..7294de7d6 --- /dev/null +++ b/pkg/sentry/fsimpl/gofer/host_named_pipe.go @@ -0,0 +1,97 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package gofer + +import ( + "fmt" + "sync" + "time" + + "golang.org/x/sys/unix" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/syserror" +) + +// Global pipe used by blockUntilNonblockingPipeHasWriter since we can't create +// pipes after sentry initialization due to syscall filters. +var ( + tempPipeMu sync.Mutex + tempPipeReadFD int + tempPipeWriteFD int + tempPipeBuf [1]byte +) + +func init() { + var pipeFDs [2]int + if err := unix.Pipe(pipeFDs[:]); err != nil { + panic(fmt.Sprintf("failed to create pipe for gofer.blockUntilNonblockingPipeHasWriter: %v", err)) + } + tempPipeReadFD = pipeFDs[0] + tempPipeWriteFD = pipeFDs[1] +} + +func blockUntilNonblockingPipeHasWriter(ctx context.Context, fd int32) error { + for { + ok, err := nonblockingPipeHasWriter(fd) + if err != nil { + return err + } + if ok { + return nil + } + if err := sleepBetweenNamedPipeOpenChecks(ctx); err != nil { + return err + } + } +} + +func nonblockingPipeHasWriter(fd int32) (bool, error) { + tempPipeMu.Lock() + defer tempPipeMu.Unlock() + // Copy 1 byte from fd into the temporary pipe. + n, err := unix.Tee(int(fd), tempPipeWriteFD, 1, unix.SPLICE_F_NONBLOCK) + if err == syserror.EAGAIN { + // The pipe represented by fd is empty, but has a writer. + return true, nil + } + if err != nil { + return false, err + } + if n == 0 { + // The pipe represented by fd is empty and has no writer. + return false, nil + } + // The pipe represented by fd is non-empty, so it either has, or has + // previously had, a writer. Remove the byte copied to the temporary pipe + // before returning. + if n, err := unix.Read(tempPipeReadFD, tempPipeBuf[:]); err != nil || n != 1 { + panic(fmt.Sprintf("failed to drain pipe for gofer.blockUntilNonblockingPipeHasWriter: got (%d, %v), wanted (1, nil)", n, err)) + } + return true, nil +} + +func sleepBetweenNamedPipeOpenChecks(ctx context.Context) error { + t := time.NewTimer(100 * time.Millisecond) + defer t.Stop() + cancel := ctx.SleepStart() + select { + case <-t.C: + ctx.SleepFinish(true) + return nil + case <-cancel: + ctx.SleepFinish(false) + return syserror.ErrInterrupted + } +} diff --git a/pkg/sentry/fsimpl/gofer/regular_file.go b/pkg/sentry/fsimpl/gofer/regular_file.go index 0d10cf7ac..09f142cfc 100644 --- a/pkg/sentry/fsimpl/gofer/regular_file.go +++ b/pkg/sentry/fsimpl/gofer/regular_file.go @@ -24,11 +24,11 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/log" + "gvisor.dev/gvisor/pkg/p9" "gvisor.dev/gvisor/pkg/safemem" "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sentry/pgalloc" - "gvisor.dev/gvisor/pkg/sentry/platform" "gvisor.dev/gvisor/pkg/sentry/usage" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/syserror" @@ -67,12 +67,46 @@ func (fd *regularFileFD) OnClose(ctx context.Context) error { return d.handle.file.flush(ctx) } +// Allocate implements vfs.FileDescriptionImpl.Allocate. +func (fd *regularFileFD) Allocate(ctx context.Context, mode, offset, length uint64) error { + + d := fd.dentry() + d.metadataMu.Lock() + defer d.metadataMu.Unlock() + + size := offset + length + + // Allocating a smaller size is a noop. + if size <= d.size { + return nil + } + + d.handleMu.Lock() + defer d.handleMu.Unlock() + + err := d.handle.file.allocate(ctx, p9.ToAllocateMode(mode), offset, length) + if err != nil { + return err + } + d.dataMu.Lock() + atomic.StoreUint64(&d.size, size) + d.dataMu.Unlock() + if !d.cachedMetadataAuthoritative() { + d.touchCMtimeLocked() + } + return nil +} + // PRead implements vfs.FileDescriptionImpl.PRead. func (fd *regularFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { if offset < 0 { return 0, syserror.EINVAL } - if opts.Flags != 0 { + + // Check that flags are supported. + // + // TODO(gvisor.dev/issue/2601): Support select preadv2 flags. + if opts.Flags&^linux.RWF_HIPRI != 0 { return 0, syserror.EOPNOTSUPP } @@ -120,21 +154,53 @@ func (fd *regularFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts // PWrite implements vfs.FileDescriptionImpl.PWrite. func (fd *regularFileFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + n, _, err := fd.pwrite(ctx, src, offset, opts) + return n, err +} + +// pwrite returns the number of bytes written, final offset, error. The final +// offset should be ignored by PWrite. +func (fd *regularFileFD) pwrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (written, finalOff int64, err error) { if offset < 0 { - return 0, syserror.EINVAL + return 0, offset, syserror.EINVAL } - if opts.Flags != 0 { - return 0, syserror.EOPNOTSUPP + + // Check that flags are supported. + // + // TODO(gvisor.dev/issue/2601): Support select pwritev2 flags. + if opts.Flags&^linux.RWF_HIPRI != 0 { + return 0, offset, syserror.EOPNOTSUPP + } + + d := fd.dentry() + // If the fd was opened with O_APPEND, make sure the file size is updated. + // There is a possible race here if size is modified externally after + // metadata cache is updated. + if fd.vfsfd.StatusFlags()&linux.O_APPEND != 0 && !d.cachedMetadataAuthoritative() { + if err := d.updateFromGetattr(ctx); err != nil { + return 0, offset, err + } + } + + d.metadataMu.Lock() + defer d.metadataMu.Unlock() + // Set offset to file size if the fd was opened with O_APPEND. + if fd.vfsfd.StatusFlags()&linux.O_APPEND != 0 { + // Holding d.metadataMu is sufficient for reading d.size. + offset = int64(d.size) } limit, err := vfs.CheckLimit(ctx, offset, src.NumBytes()) if err != nil { - return 0, err + return 0, offset, err } src = src.TakeFirst64(limit) + n, err := fd.pwriteLocked(ctx, src, offset, opts) + return n, offset + n, err +} +// Preconditions: fd.dentry().metatdataMu must be locked. +func (fd *regularFileFD) pwriteLocked(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { d := fd.dentry() - d.metadataMu.Lock() - defer d.metadataMu.Unlock() if d.fs.opts.interop != InteropModeShared { // Compare Linux's mm/filemap.c:__generic_file_write_iter() => // file_update_time(). This is d.touchCMtime(), but without locking @@ -154,12 +220,12 @@ func (fd *regularFileFD) PWrite(ctx context.Context, src usermem.IOSequence, off return 0, syserror.EINVAL } mr := memmap.MappableRange{pgstart, pgend} - var freed []platform.FileRange + var freed []memmap.FileRange d.dataMu.Lock() cseg := d.cache.LowerBoundSegment(mr.Start) for cseg.Ok() && cseg.Start() < mr.End { cseg = d.cache.Isolate(cseg, mr) - freed = append(freed, platform.FileRange{cseg.Value(), cseg.Value() + cseg.Range().Length()}) + freed = append(freed, memmap.FileRange{cseg.Value(), cseg.Value() + cseg.Range().Length()}) cseg = d.cache.Remove(cseg).NextSegment() } d.dataMu.Unlock() @@ -197,8 +263,8 @@ func (fd *regularFileFD) PWrite(ctx context.Context, src usermem.IOSequence, off // Write implements vfs.FileDescriptionImpl.Write. func (fd *regularFileFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { fd.mu.Lock() - n, err := fd.PWrite(ctx, src, fd.off, opts) - fd.off += n + n, off, err := fd.pwrite(ctx, src, fd.off, opts) + fd.off = off fd.mu.Unlock() return n, err } @@ -489,15 +555,24 @@ func (d *dentry) writeback(ctx context.Context, offset, size int64) error { func (fd *regularFileFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { fd.mu.Lock() defer fd.mu.Unlock() + newOffset, err := regularFileSeekLocked(ctx, fd.dentry(), fd.off, offset, whence) + if err != nil { + return 0, err + } + fd.off = newOffset + return newOffset, nil +} + +// Calculate the new offset for a seek operation on a regular file. +func regularFileSeekLocked(ctx context.Context, d *dentry, fdOffset, offset int64, whence int32) (int64, error) { switch whence { case linux.SEEK_SET: // Use offset as specified. case linux.SEEK_CUR: - offset += fd.off + offset += fdOffset case linux.SEEK_END, linux.SEEK_DATA, linux.SEEK_HOLE: // Ensure file size is up to date. - d := fd.dentry() - if fd.filesystem().opts.interop == InteropModeShared { + if !d.cachedMetadataAuthoritative() { if err := d.updateFromGetattr(ctx); err != nil { return 0, err } @@ -525,7 +600,6 @@ func (fd *regularFileFD) Seek(ctx context.Context, offset int64, whence int32) ( if offset < 0 { return 0, syserror.EINVAL } - fd.off = offset return offset, nil } @@ -536,20 +610,19 @@ func (fd *regularFileFD) Sync(ctx context.Context) error { func (d *dentry) syncSharedHandle(ctx context.Context) error { d.handleMu.RLock() - if !d.handleWritable { - d.handleMu.RUnlock() - return nil - } - d.dataMu.Lock() - // Write dirty cached data to the remote file. - err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, d.fs.mfp.MemoryFile(), d.handle.writeFromBlocksAt) - d.dataMu.Unlock() - if err == nil { - // Sync the remote file. - err = d.handle.sync(ctx) + defer d.handleMu.RUnlock() + + if d.handleWritable { + d.dataMu.Lock() + // Write dirty cached data to the remote file. + err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, d.fs.mfp.MemoryFile(), d.handle.writeFromBlocksAt) + d.dataMu.Unlock() + if err != nil { + return err + } } - d.handleMu.RUnlock() - return err + // Sync the remote file. + return d.handle.sync(ctx) } // ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap. @@ -747,7 +820,7 @@ func maxFillRange(required, optional memmap.MappableRange) memmap.MappableRange // InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable. func (d *dentry) InvalidateUnsavable(ctx context.Context) error { - // Whether we have a host fd (and consequently what platform.File is + // Whether we have a host fd (and consequently what memmap.File is // mapped) can change across save/restore, so invalidate all translations // unconditionally. d.mapsMu.Lock() @@ -795,8 +868,8 @@ func (d *dentry) Evict(ctx context.Context, er pgalloc.EvictableRange) { } } -// dentryPlatformFile implements platform.File. It exists solely because dentry -// cannot implement both vfs.DentryImpl.IncRef and platform.File.IncRef. +// dentryPlatformFile implements memmap.File. It exists solely because dentry +// cannot implement both vfs.DentryImpl.IncRef and memmap.File.IncRef. // // dentryPlatformFile is only used when a host FD representing the remote file // is available (i.e. dentry.handle.fd >= 0), and that FD is used for @@ -804,7 +877,7 @@ func (d *dentry) Evict(ctx context.Context, er pgalloc.EvictableRange) { type dentryPlatformFile struct { *dentry - // fdRefs counts references on platform.File offsets. fdRefs is protected + // fdRefs counts references on memmap.File offsets. fdRefs is protected // by dentry.dataMu. fdRefs fsutil.FrameRefSet @@ -816,29 +889,29 @@ type dentryPlatformFile struct { hostFileMapperInitOnce sync.Once } -// IncRef implements platform.File.IncRef. -func (d *dentryPlatformFile) IncRef(fr platform.FileRange) { +// IncRef implements memmap.File.IncRef. +func (d *dentryPlatformFile) IncRef(fr memmap.FileRange) { d.dataMu.Lock() d.fdRefs.IncRefAndAccount(fr) d.dataMu.Unlock() } -// DecRef implements platform.File.DecRef. -func (d *dentryPlatformFile) DecRef(fr platform.FileRange) { +// DecRef implements memmap.File.DecRef. +func (d *dentryPlatformFile) DecRef(fr memmap.FileRange) { d.dataMu.Lock() d.fdRefs.DecRefAndAccount(fr) d.dataMu.Unlock() } -// MapInternal implements platform.File.MapInternal. -func (d *dentryPlatformFile) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) { +// MapInternal implements memmap.File.MapInternal. +func (d *dentryPlatformFile) MapInternal(fr memmap.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) { d.handleMu.RLock() bs, err := d.hostFileMapper.MapInternal(fr, int(d.handle.fd), at.Write) d.handleMu.RUnlock() return bs, err } -// FD implements platform.File.FD. +// FD implements memmap.File.FD. func (d *dentryPlatformFile) FD() int { d.handleMu.RLock() fd := d.handle.fd diff --git a/pkg/sentry/fsimpl/gofer/special_file.go b/pkg/sentry/fsimpl/gofer/special_file.go index a464e6a94..811528982 100644 --- a/pkg/sentry/fsimpl/gofer/special_file.go +++ b/pkg/sentry/fsimpl/gofer/special_file.go @@ -16,20 +16,22 @@ package gofer import ( "sync" + "sync/atomic" "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/fdnotifier" "gvisor.dev/gvisor/pkg/safemem" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/syserror" "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/pkg/waiter" ) -// specialFileFD implements vfs.FileDescriptionImpl for files other than -// regular files, directories, and symlinks: pipes, sockets, etc. It is also -// used for regular files when filesystemOptions.specialRegularFiles is in -// effect. specialFileFD differs from regularFileFD by using per-FD handles -// instead of shared per-dentry handles, and never buffering I/O. +// specialFileFD implements vfs.FileDescriptionImpl for pipes, sockets, device +// special files, and (when filesystemOptions.regularFilesUseSpecialFileFD is +// in effect) regular files. specialFileFD differs from regularFileFD by using +// per-FD handles instead of shared per-dentry handles, and never buffering I/O. type specialFileFD struct { fileDescription @@ -40,13 +42,48 @@ type specialFileFD struct { // file offset is significant, i.e. a regular file. seekable is immutable. seekable bool + // haveQueue is true if this file description represents a file for which + // queue may send I/O readiness events. haveQueue is immutable. + haveQueue bool + queue waiter.Queue + // If seekable is true, off is the file offset. off is protected by mu. mu sync.Mutex off int64 } +func newSpecialFileFD(h handle, mnt *vfs.Mount, d *dentry, locks *vfs.FileLocks, flags uint32) (*specialFileFD, error) { + ftype := d.fileType() + seekable := ftype == linux.S_IFREG + haveQueue := (ftype == linux.S_IFIFO || ftype == linux.S_IFSOCK) && h.fd >= 0 + fd := &specialFileFD{ + handle: h, + seekable: seekable, + haveQueue: haveQueue, + } + fd.LockFD.Init(locks) + if haveQueue { + if err := fdnotifier.AddFD(h.fd, &fd.queue); err != nil { + return nil, err + } + } + if err := fd.vfsfd.Init(fd, flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{ + DenyPRead: !seekable, + DenyPWrite: !seekable, + }); err != nil { + if haveQueue { + fdnotifier.RemoveFD(h.fd) + } + return nil, err + } + return fd, nil +} + // Release implements vfs.FileDescriptionImpl.Release. func (fd *specialFileFD) Release() { + if fd.haveQueue { + fdnotifier.RemoveFD(fd.handle.fd) + } fd.handle.close(context.Background()) fs := fd.vfsfd.Mount().Filesystem().Impl().(*filesystem) fs.syncMu.Lock() @@ -62,12 +99,44 @@ func (fd *specialFileFD) OnClose(ctx context.Context) error { return fd.handle.file.flush(ctx) } +// Readiness implements waiter.Waitable.Readiness. +func (fd *specialFileFD) Readiness(mask waiter.EventMask) waiter.EventMask { + if fd.haveQueue { + return fdnotifier.NonBlockingPoll(fd.handle.fd, mask) + } + return fd.fileDescription.Readiness(mask) +} + +// EventRegister implements waiter.Waitable.EventRegister. +func (fd *specialFileFD) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + if fd.haveQueue { + fd.queue.EventRegister(e, mask) + fdnotifier.UpdateFD(fd.handle.fd) + return + } + fd.fileDescription.EventRegister(e, mask) +} + +// EventUnregister implements waiter.Waitable.EventUnregister. +func (fd *specialFileFD) EventUnregister(e *waiter.Entry) { + if fd.haveQueue { + fd.queue.EventUnregister(e) + fdnotifier.UpdateFD(fd.handle.fd) + return + } + fd.fileDescription.EventUnregister(e) +} + // PRead implements vfs.FileDescriptionImpl.PRead. func (fd *specialFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { if fd.seekable && offset < 0 { return 0, syserror.EINVAL } - if opts.Flags != 0 { + + // Check that flags are supported. + // + // TODO(gvisor.dev/issue/2601): Support select preadv2 flags. + if opts.Flags&^linux.RWF_HIPRI != 0 { return 0, syserror.EOPNOTSUPP } @@ -76,11 +145,14 @@ func (fd *specialFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offs // mmap due to lock ordering; MM locks precede dentry.dataMu. That doesn't // hold here since specialFileFD doesn't client-cache data. Just buffer the // read instead. - if d := fd.dentry(); d.fs.opts.interop != InteropModeShared { + if d := fd.dentry(); d.cachedMetadataAuthoritative() { d.touchAtime(fd.vfsfd.Mount()) } buf := make([]byte, dst.NumBytes()) n, err := fd.handle.readToBlocksAt(ctx, safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf)), uint64(offset)) + if err == syserror.EAGAIN { + err = syserror.ErrWouldBlock + } if n == 0 { return 0, err } @@ -105,32 +177,76 @@ func (fd *specialFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts // PWrite implements vfs.FileDescriptionImpl.PWrite. func (fd *specialFileFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + n, _, err := fd.pwrite(ctx, src, offset, opts) + return n, err +} + +// pwrite returns the number of bytes written, final offset, error. The final +// offset should be ignored by PWrite. +func (fd *specialFileFD) pwrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (written, finalOff int64, err error) { if fd.seekable && offset < 0 { - return 0, syserror.EINVAL + return 0, offset, syserror.EINVAL } - if opts.Flags != 0 { - return 0, syserror.EOPNOTSUPP + + // Check that flags are supported. + // + // TODO(gvisor.dev/issue/2601): Support select pwritev2 flags. + if opts.Flags&^linux.RWF_HIPRI != 0 { + return 0, offset, syserror.EOPNOTSUPP + } + + d := fd.dentry() + // If the regular file fd was opened with O_APPEND, make sure the file size + // is updated. There is a possible race here if size is modified externally + // after metadata cache is updated. + if fd.seekable && fd.vfsfd.StatusFlags()&linux.O_APPEND != 0 && !d.cachedMetadataAuthoritative() { + if err := d.updateFromGetattr(ctx); err != nil { + return 0, offset, err + } } if fd.seekable { + // We need to hold the metadataMu *while* writing to a regular file. + d.metadataMu.Lock() + defer d.metadataMu.Unlock() + + // Set offset to file size if the regular file was opened with O_APPEND. + if fd.vfsfd.StatusFlags()&linux.O_APPEND != 0 { + // Holding d.metadataMu is sufficient for reading d.size. + offset = int64(d.size) + } limit, err := vfs.CheckLimit(ctx, offset, src.NumBytes()) if err != nil { - return 0, err + return 0, offset, err } src = src.TakeFirst64(limit) } // Do a buffered write. See rationale in PRead. - if d := fd.dentry(); d.fs.opts.interop != InteropModeShared { + if d.cachedMetadataAuthoritative() { d.touchCMtime() } buf := make([]byte, src.NumBytes()) // Don't do partial writes if we get a partial read from src. if _, err := src.CopyIn(ctx, buf); err != nil { - return 0, err + return 0, offset, err } n, err := fd.handle.writeFromBlocksAt(ctx, safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf)), uint64(offset)) - return int64(n), err + if err == syserror.EAGAIN { + err = syserror.ErrWouldBlock + } + finalOff = offset + // Update file size for regular files. + if fd.seekable { + finalOff += int64(n) + // d.metadataMu is already locked at this point. + if uint64(finalOff) > d.size { + d.dataMu.Lock() + defer d.dataMu.Unlock() + atomic.StoreUint64(&d.size, uint64(finalOff)) + } + } + return int64(n), finalOff, err } // Write implements vfs.FileDescriptionImpl.Write. @@ -140,8 +256,8 @@ func (fd *specialFileFD) Write(ctx context.Context, src usermem.IOSequence, opts } fd.mu.Lock() - n, err := fd.PWrite(ctx, src, fd.off, opts) - fd.off += n + n, off, err := fd.pwrite(ctx, src, fd.off, opts) + fd.off = off fd.mu.Unlock() return n, err } @@ -153,27 +269,15 @@ func (fd *specialFileFD) Seek(ctx context.Context, offset int64, whence int32) ( } fd.mu.Lock() defer fd.mu.Unlock() - switch whence { - case linux.SEEK_SET: - // Use offset as given. - case linux.SEEK_CUR: - offset += fd.off - default: - // SEEK_END, SEEK_DATA, and SEEK_HOLE aren't supported since it's not - // clear that file size is even meaningful for these files. - return 0, syserror.EINVAL - } - if offset < 0 { - return 0, syserror.EINVAL + newOffset, err := regularFileSeekLocked(ctx, fd.dentry(), fd.off, offset, whence) + if err != nil { + return 0, err } - fd.off = offset - return offset, nil + fd.off = newOffset + return newOffset, nil } // Sync implements vfs.FileDescriptionImpl.Sync. func (fd *specialFileFD) Sync(ctx context.Context) error { - if !fd.vfsfd.IsWritable() { - return nil - } - return fd.handle.sync(ctx) + return fd.dentry().syncSharedHandle(ctx) } diff --git a/pkg/sentry/fsimpl/gofer/time.go b/pkg/sentry/fsimpl/gofer/time.go index 2608e7e1d..0eef4e16e 100644 --- a/pkg/sentry/fsimpl/gofer/time.go +++ b/pkg/sentry/fsimpl/gofer/time.go @@ -36,8 +36,11 @@ func statxTimestampFromDentry(ns int64) linux.StatxTimestamp { } } -// Preconditions: fs.interop != InteropModeShared. +// Preconditions: d.cachedMetadataAuthoritative() == true. func (d *dentry) touchAtime(mnt *vfs.Mount) { + if mnt.Flags.NoATime { + return + } if err := mnt.CheckBeginWrite(); err != nil { return } @@ -48,8 +51,8 @@ func (d *dentry) touchAtime(mnt *vfs.Mount) { mnt.EndWrite() } -// Preconditions: fs.interop != InteropModeShared. The caller has successfully -// called vfs.Mount.CheckBeginWrite(). +// Preconditions: d.cachedMetadataAuthoritative() == true. The caller has +// successfully called vfs.Mount.CheckBeginWrite(). func (d *dentry) touchCtime() { now := d.fs.clock.Now().Nanoseconds() d.metadataMu.Lock() @@ -57,8 +60,8 @@ func (d *dentry) touchCtime() { d.metadataMu.Unlock() } -// Preconditions: fs.interop != InteropModeShared. The caller has successfully -// called vfs.Mount.CheckBeginWrite(). +// Preconditions: d.cachedMetadataAuthoritative() == true. The caller has +// successfully called vfs.Mount.CheckBeginWrite(). func (d *dentry) touchCMtime() { now := d.fs.clock.Now().Nanoseconds() d.metadataMu.Lock() @@ -67,6 +70,8 @@ func (d *dentry) touchCMtime() { d.metadataMu.Unlock() } +// Preconditions: d.cachedMetadataAuthoritative() == true. The caller has +// locked d.metadataMu. func (d *dentry) touchCMtimeLocked() { now := d.fs.clock.Now().Nanoseconds() atomic.StoreInt64(&d.mtime, now) diff --git a/pkg/sentry/fsimpl/host/BUILD b/pkg/sentry/fsimpl/host/BUILD index ca0fe6d2b..bd701bbc7 100644 --- a/pkg/sentry/fsimpl/host/BUILD +++ b/pkg/sentry/fsimpl/host/BUILD @@ -22,17 +22,18 @@ go_library( "//pkg/context", "//pkg/fdnotifier", "//pkg/fspath", + "//pkg/iovec", "//pkg/log", "//pkg/refs", "//pkg/safemem", "//pkg/sentry/arch", "//pkg/sentry/fs/fsutil", + "//pkg/sentry/fs/lock", "//pkg/sentry/fsimpl/kernfs", "//pkg/sentry/hostfd", "//pkg/sentry/kernel", "//pkg/sentry/kernel/auth", "//pkg/sentry/memmap", - "//pkg/sentry/platform", "//pkg/sentry/socket/control", "//pkg/sentry/socket/unix", "//pkg/sentry/socket/unix/transport", diff --git a/pkg/sentry/fsimpl/host/host.go b/pkg/sentry/fsimpl/host/host.go index 18b127521..c894f2ca0 100644 --- a/pkg/sentry/fsimpl/host/host.go +++ b/pkg/sentry/fsimpl/host/host.go @@ -28,6 +28,7 @@ import ( "gvisor.dev/gvisor/pkg/fspath" "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/refs" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" "gvisor.dev/gvisor/pkg/sentry/hostfd" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" @@ -90,7 +91,9 @@ func NewFD(ctx context.Context, mnt *vfs.Mount, hostFD int, opts *NewFDOptions) isTTY: opts.IsTTY, wouldBlock: wouldBlock(uint32(fileType)), seekable: seekable, - canMap: canMap(uint32(fileType)), + // NOTE(b/38213152): Technically, some obscure char devices can be memory + // mapped, but we only allow regular files. + canMap: fileType == linux.S_IFREG, } i.pf.inode = i @@ -182,6 +185,8 @@ type inode struct { kernfs.InodeNotDirectory kernfs.InodeNotSymlink + locks vfs.FileLocks + // When the reference count reaches zero, the host fd is closed. refs.AtomicRefCount @@ -254,7 +259,7 @@ func (i *inode) Mode() linux.FileMode { } // Stat implements kernfs.Inode. -func (i *inode) Stat(vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { +func (i *inode) Stat(ctx context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { if opts.Mask&linux.STATX__RESERVED != 0 { return linux.Statx{}, syserror.EINVAL } @@ -368,7 +373,7 @@ func (i *inode) fstat(fs *filesystem) (linux.Statx, error) { // SetStat implements kernfs.Inode. func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error { - s := opts.Stat + s := &opts.Stat m := s.Mask if m == 0 { @@ -381,7 +386,7 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre if err := syscall.Fstat(i.hostFD, &hostStat); err != nil { return err } - if err := vfs.CheckSetStat(ctx, creds, &s, linux.FileMode(hostStat.Mode&linux.PermissionsMask), auth.KUID(hostStat.Uid), auth.KGID(hostStat.Gid)); err != nil { + if err := vfs.CheckSetStat(ctx, creds, &opts, linux.FileMode(hostStat.Mode), auth.KUID(hostStat.Uid), auth.KGID(hostStat.Gid)); err != nil { return err } @@ -391,6 +396,9 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre } } if m&linux.STATX_SIZE != 0 { + if hostStat.Mode&linux.S_IFMT != linux.S_IFREG { + return syserror.EINVAL + } if err := syscall.Ftruncate(i.hostFD, int64(s.Size)); err != nil { return err } @@ -454,10 +462,12 @@ func (i *inode) open(ctx context.Context, d *vfs.Dentry, mnt *vfs.Mount, flags u fileType := s.Mode & linux.FileTypeMask // Constrain flags to a subset we can handle. - // TODO(gvisor.dev/issue/1672): implement behavior corresponding to these allowed flags. - flags &= syscall.O_ACCMODE | syscall.O_DIRECT | syscall.O_NONBLOCK | syscall.O_DSYNC | syscall.O_SYNC | syscall.O_APPEND + // + // TODO(gvisor.dev/issue/2601): Support O_NONBLOCK by adding RWF_NOWAIT to pread/pwrite calls. + flags &= syscall.O_ACCMODE | syscall.O_NONBLOCK | syscall.O_DSYNC | syscall.O_SYNC | syscall.O_APPEND - if fileType == syscall.S_IFSOCK { + switch fileType { + case syscall.S_IFSOCK: if i.isTTY { log.Warningf("cannot use host socket fd %d as TTY", i.hostFD) return nil, syserror.ENOTTY @@ -468,35 +478,41 @@ func (i *inode) open(ctx context.Context, d *vfs.Dentry, mnt *vfs.Mount, flags u return nil, err } // Currently, we only allow Unix sockets to be imported. - return unixsocket.NewFileDescription(ep, ep.Type(), flags, mnt, d) - } + return unixsocket.NewFileDescription(ep, ep.Type(), flags, mnt, d, &i.locks) - // TODO(gvisor.dev/issue/1672): Whitelist specific file types here, so that - // we don't allow importing arbitrary file types without proper support. - if i.isTTY { - fd := &TTYFileDescription{ - fileDescription: fileDescription{inode: i}, - termios: linux.DefaultSlaveTermios, + case syscall.S_IFREG, syscall.S_IFIFO, syscall.S_IFCHR: + if i.isTTY { + fd := &TTYFileDescription{ + fileDescription: fileDescription{inode: i}, + termios: linux.DefaultSlaveTermios, + } + fd.LockFD.Init(&i.locks) + vfsfd := &fd.vfsfd + if err := vfsfd.Init(fd, flags, mnt, d, &vfs.FileDescriptionOptions{}); err != nil { + return nil, err + } + return vfsfd, nil } + + fd := &fileDescription{inode: i} + fd.LockFD.Init(&i.locks) vfsfd := &fd.vfsfd if err := vfsfd.Init(fd, flags, mnt, d, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } return vfsfd, nil - } - fd := &fileDescription{inode: i} - vfsfd := &fd.vfsfd - if err := vfsfd.Init(fd, flags, mnt, d, &vfs.FileDescriptionOptions{}); err != nil { - return nil, err + default: + log.Warningf("cannot import host fd %d with file type %o", i.hostFD, fileType) + return nil, syserror.EPERM } - return vfsfd, nil } // fileDescription is embedded by host fd implementations of FileDescriptionImpl. type fileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl + vfs.LockFD // inode is vfsfd.Dentry().Impl().(*kernfs.Dentry).Inode().(*inode), but // cached to reduce indirections and casting. fileDescription does not hold @@ -521,8 +537,8 @@ func (f *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) } // Stat implements vfs.FileDescriptionImpl. -func (f *fileDescription) Stat(_ context.Context, opts vfs.StatOptions) (linux.Statx, error) { - return f.inode.Stat(f.vfsfd.Mount().Filesystem(), opts) +func (f *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { + return f.inode.Stat(ctx, f.vfsfd.Mount().Filesystem(), opts) } // Release implements vfs.FileDescriptionImpl. @@ -530,6 +546,16 @@ func (f *fileDescription) Release() { // noop } +// Allocate implements vfs.FileDescriptionImpl. +func (f *fileDescription) Allocate(ctx context.Context, mode, offset, length uint64) error { + if !f.inode.seekable { + return syserror.ESPIPE + } + + // TODO(gvisor.dev/issue/2923): Implement Allocate for non-pipe hostfds. + return syserror.EOPNOTSUPP +} + // PRead implements FileDescriptionImpl. func (f *fileDescription) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { i := f.inode @@ -556,7 +582,7 @@ func (f *fileDescription) Read(ctx context.Context, dst usermem.IOSequence, opts } return n, err } - // TODO(gvisor.dev/issue/1672): Cache pages, when forced to do so. + f.offsetMu.Lock() n, err := readFromHostFD(ctx, i.hostFD, dst, f.offset, opts.Flags) f.offset += n @@ -565,8 +591,10 @@ func (f *fileDescription) Read(ctx context.Context, dst usermem.IOSequence, opts } func readFromHostFD(ctx context.Context, hostFD int, dst usermem.IOSequence, offset int64, flags uint32) (int64, error) { - // TODO(gvisor.dev/issue/1672): Support select preadv2 flags. - if flags != 0 { + // Check that flags are supported. + // + // TODO(gvisor.dev/issue/2601): Support select preadv2 flags. + if flags&^linux.RWF_HIPRI != 0 { return 0, syserror.EOPNOTSUPP } reader := hostfd.GetReadWriterAt(int32(hostFD), offset, flags) @@ -577,41 +605,58 @@ func readFromHostFD(ctx context.Context, hostFD int, dst usermem.IOSequence, off // PWrite implements FileDescriptionImpl. func (f *fileDescription) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { - i := f.inode - if !i.seekable { + if !f.inode.seekable { return 0, syserror.ESPIPE } - return writeToHostFD(ctx, i.hostFD, src, offset, opts.Flags) + return f.writeToHostFD(ctx, src, offset, opts.Flags) } // Write implements FileDescriptionImpl. func (f *fileDescription) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { i := f.inode if !i.seekable { - n, err := writeToHostFD(ctx, i.hostFD, src, -1, opts.Flags) + n, err := f.writeToHostFD(ctx, src, -1, opts.Flags) if isBlockError(err) { err = syserror.ErrWouldBlock } return n, err } - // TODO(gvisor.dev/issue/1672): Cache pages, when forced to do so. - // TODO(gvisor.dev/issue/1672): Write to end of file and update offset if O_APPEND is set on this file. + f.offsetMu.Lock() - n, err := writeToHostFD(ctx, i.hostFD, src, f.offset, opts.Flags) + // NOTE(gvisor.dev/issue/2983): O_APPEND may cause memory corruption if + // another process modifies the host file between retrieving the file size + // and writing to the host fd. This is an unavoidable race condition because + // we cannot enforce synchronization on the host. + if f.vfsfd.StatusFlags()&linux.O_APPEND != 0 { + var s syscall.Stat_t + if err := syscall.Fstat(i.hostFD, &s); err != nil { + f.offsetMu.Unlock() + return 0, err + } + f.offset = s.Size + } + n, err := f.writeToHostFD(ctx, src, f.offset, opts.Flags) f.offset += n f.offsetMu.Unlock() return n, err } -func writeToHostFD(ctx context.Context, hostFD int, src usermem.IOSequence, offset int64, flags uint32) (int64, error) { - // TODO(gvisor.dev/issue/1672): Support select pwritev2 flags. +func (f *fileDescription) writeToHostFD(ctx context.Context, src usermem.IOSequence, offset int64, flags uint32) (int64, error) { + hostFD := f.inode.hostFD + // TODO(gvisor.dev/issue/2601): Support select pwritev2 flags. if flags != 0 { return 0, syserror.EOPNOTSUPP } writer := hostfd.GetReadWriterAt(int32(hostFD), offset, flags) n, err := src.CopyInTo(ctx, writer) hostfd.PutReadWriterAt(writer) + // NOTE(gvisor.dev/issue/2979): We always sync everything, even for O_DSYNC. + if n > 0 && f.vfsfd.StatusFlags()&(linux.O_DSYNC|linux.O_SYNC) != 0 { + if syncErr := unix.Fsync(hostFD); syncErr != nil { + return int64(n), syncErr + } + } return int64(n), err } @@ -682,7 +727,7 @@ func (f *fileDescription) Seek(_ context.Context, offset int64, whence int32) (i // Sync implements FileDescriptionImpl. func (f *fileDescription) Sync(context.Context) error { - // TODO(gvisor.dev/issue/1672): Currently we do not support the SyncData optimization, so we always sync everything. + // TODO(gvisor.dev/issue/1897): Currently, we always sync everything. return unix.Fsync(f.inode.hostFD) } @@ -712,3 +757,13 @@ func (f *fileDescription) EventUnregister(e *waiter.Entry) { func (f *fileDescription) Readiness(mask waiter.EventMask) waiter.EventMask { return fdnotifier.NonBlockingPoll(int32(f.inode.hostFD), mask) } + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (f *fileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return f.Locks().LockPOSIX(ctx, &f.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (f *fileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return f.Locks().UnlockPOSIX(ctx, &f.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/host/mmap.go b/pkg/sentry/fsimpl/host/mmap.go index 8545a82f0..65d3af38c 100644 --- a/pkg/sentry/fsimpl/host/mmap.go +++ b/pkg/sentry/fsimpl/host/mmap.go @@ -19,13 +19,12 @@ import ( "gvisor.dev/gvisor/pkg/safemem" "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" "gvisor.dev/gvisor/pkg/sentry/memmap" - "gvisor.dev/gvisor/pkg/sentry/platform" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/usermem" ) -// inodePlatformFile implements platform.File. It exists solely because inode -// cannot implement both kernfs.Inode.IncRef and platform.File.IncRef. +// inodePlatformFile implements memmap.File. It exists solely because inode +// cannot implement both kernfs.Inode.IncRef and memmap.File.IncRef. // // inodePlatformFile should only be used if inode.canMap is true. type inodePlatformFile struct { @@ -34,7 +33,7 @@ type inodePlatformFile struct { // fdRefsMu protects fdRefs. fdRefsMu sync.Mutex - // fdRefs counts references on platform.File offsets. It is used solely for + // fdRefs counts references on memmap.File offsets. It is used solely for // memory accounting. fdRefs fsutil.FrameRefSet @@ -45,32 +44,32 @@ type inodePlatformFile struct { fileMapperInitOnce sync.Once } -// IncRef implements platform.File.IncRef. +// IncRef implements memmap.File.IncRef. // // Precondition: i.inode.canMap must be true. -func (i *inodePlatformFile) IncRef(fr platform.FileRange) { +func (i *inodePlatformFile) IncRef(fr memmap.FileRange) { i.fdRefsMu.Lock() i.fdRefs.IncRefAndAccount(fr) i.fdRefsMu.Unlock() } -// DecRef implements platform.File.DecRef. +// DecRef implements memmap.File.DecRef. // // Precondition: i.inode.canMap must be true. -func (i *inodePlatformFile) DecRef(fr platform.FileRange) { +func (i *inodePlatformFile) DecRef(fr memmap.FileRange) { i.fdRefsMu.Lock() i.fdRefs.DecRefAndAccount(fr) i.fdRefsMu.Unlock() } -// MapInternal implements platform.File.MapInternal. +// MapInternal implements memmap.File.MapInternal. // // Precondition: i.inode.canMap must be true. -func (i *inodePlatformFile) MapInternal(fr platform.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) { +func (i *inodePlatformFile) MapInternal(fr memmap.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) { return i.fileMapper.MapInternal(fr, i.hostFD, at.Write) } -// FD implements platform.File.FD. +// FD implements memmap.File.FD. func (i *inodePlatformFile) FD() int { return i.hostFD } diff --git a/pkg/sentry/fsimpl/host/socket.go b/pkg/sentry/fsimpl/host/socket.go index 38f1fbfba..fd16bd92d 100644 --- a/pkg/sentry/fsimpl/host/socket.go +++ b/pkg/sentry/fsimpl/host/socket.go @@ -47,11 +47,6 @@ func newEndpoint(ctx context.Context, hostFD int, queue *waiter.Queue) (transpor return ep, nil } -// maxSendBufferSize is the maximum host send buffer size allowed for endpoint. -// -// N.B. 8MB is the default maximum on Linux (2 * sysctl_wmem_max). -const maxSendBufferSize = 8 << 20 - // ConnectedEndpoint is an implementation of transport.ConnectedEndpoint and // transport.Receiver. It is backed by a host fd that was imported at sentry // startup. This fd is shared with a hostfs inode, which retains ownership of @@ -114,10 +109,6 @@ func (c *ConnectedEndpoint) init() *syserr.Error { if err != nil { return syserr.FromError(err) } - if sndbuf > maxSendBufferSize { - log.Warningf("Socket send buffer too large: %d", sndbuf) - return syserr.ErrInvalidEndpointState - } c.stype = linux.SockType(stype) c.sndbuf = int64(sndbuf) diff --git a/pkg/sentry/fsimpl/host/socket_iovec.go b/pkg/sentry/fsimpl/host/socket_iovec.go index 584c247d2..fc0d5fd38 100644 --- a/pkg/sentry/fsimpl/host/socket_iovec.go +++ b/pkg/sentry/fsimpl/host/socket_iovec.go @@ -17,13 +17,10 @@ package host import ( "syscall" - "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/iovec" "gvisor.dev/gvisor/pkg/syserror" ) -// maxIovs is the maximum number of iovecs to pass to the host. -var maxIovs = linux.UIO_MAXIOV - // copyToMulti copies as many bytes from src to dst as possible. func copyToMulti(dst [][]byte, src []byte) { for _, d := range dst { @@ -74,7 +71,7 @@ func buildIovec(bufs [][]byte, maxlen int64, truncate bool) (length int64, iovec } } - if iovsRequired > maxIovs { + if iovsRequired > iovec.MaxIovs { // The kernel will reject our call if we pass this many iovs. // Use a single intermediate buffer instead. b := make([]byte, stopLen) diff --git a/pkg/sentry/fsimpl/host/tty.go b/pkg/sentry/fsimpl/host/tty.go index 68af6e5af..4ee9270cc 100644 --- a/pkg/sentry/fsimpl/host/tty.go +++ b/pkg/sentry/fsimpl/host/tty.go @@ -18,6 +18,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel" "gvisor.dev/gvisor/pkg/sentry/unimpl" "gvisor.dev/gvisor/pkg/sentry/vfs" @@ -325,9 +326,9 @@ func (t *TTYFileDescription) checkChange(ctx context.Context, sig linux.Signal) task := kernel.TaskFromContext(ctx) if task == nil { // No task? Linux does not have an analog for this case, but - // tty_check_change is more of a blacklist of cases than a - // whitelist, and is surprisingly permissive. Allowing the - // change seems most appropriate. + // tty_check_change only blocks specific cases and is + // surprisingly permissive. Allowing the change seems + // appropriate. return nil } @@ -377,3 +378,13 @@ func (t *TTYFileDescription) checkChange(ctx context.Context, sig linux.Signal) _ = pg.SendSignal(kernel.SignalInfoPriv(sig)) return kernel.ERESTARTSYS } + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (t *TTYFileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, typ fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return t.Locks().LockPOSIX(ctx, &t.vfsfd, uid, typ, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (t *TTYFileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return t.Locks().UnlockPOSIX(ctx, &t.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/host/util.go b/pkg/sentry/fsimpl/host/util.go index 2bc757b1a..412bdb2eb 100644 --- a/pkg/sentry/fsimpl/host/util.go +++ b/pkg/sentry/fsimpl/host/util.go @@ -49,16 +49,6 @@ func wouldBlock(fileType uint32) bool { return fileType == syscall.S_IFIFO || fileType == syscall.S_IFCHR || fileType == syscall.S_IFSOCK } -// canMap returns true if a file with fileType is allowed to be memory mapped. -// This is ported over from VFS1, but it's probably not the best way for us -// to check if a file can be memory mapped. -func canMap(fileType uint32) bool { - // TODO(gvisor.dev/issue/1672): Also allow "special files" to be mapped (see fs/host:canMap()). - // - // TODO(b/38213152): Some obscure character devices can be mapped. - return fileType == syscall.S_IFREG -} - // isBlockError checks if an error is EAGAIN or EWOULDBLOCK. // If so, they can be transformed into syserror.ErrWouldBlock. func isBlockError(err error) bool { diff --git a/pkg/sentry/fsimpl/kernfs/BUILD b/pkg/sentry/fsimpl/kernfs/BUILD index ef34cb28a..3835557fe 100644 --- a/pkg/sentry/fsimpl/kernfs/BUILD +++ b/pkg/sentry/fsimpl/kernfs/BUILD @@ -45,6 +45,7 @@ go_library( "//pkg/fspath", "//pkg/log", "//pkg/refs", + "//pkg/sentry/fs/lock", "//pkg/sentry/kernel/auth", "//pkg/sentry/memmap", "//pkg/sentry/socket/unix/transport", @@ -69,6 +70,6 @@ go_test( "//pkg/sentry/vfs", "//pkg/syserror", "//pkg/usermem", - "@com_github_google_go-cmp//cmp:go_default_library", + "@com_github_google_go_cmp//cmp:go_default_library", ], ) diff --git a/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go index 1568a9d49..c6c4472e7 100644 --- a/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go +++ b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go @@ -19,6 +19,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/vfs" "gvisor.dev/gvisor/pkg/syserror" @@ -38,7 +39,8 @@ type DynamicBytesFile struct { InodeNotDirectory InodeNotSymlink - data vfs.DynamicBytesSource + locks vfs.FileLocks + data vfs.DynamicBytesSource } var _ Inode = (*DynamicBytesFile)(nil) @@ -55,7 +57,7 @@ func (f *DynamicBytesFile) Init(creds *auth.Credentials, devMajor, devMinor uint // Open implements Inode.Open. func (f *DynamicBytesFile) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { fd := &DynamicBytesFD{} - if err := fd.Init(rp.Mount(), vfsd, f.data, opts.Flags); err != nil { + if err := fd.Init(rp.Mount(), vfsd, f.data, &f.locks, opts.Flags); err != nil { return nil, err } return &fd.vfsfd, nil @@ -77,13 +79,15 @@ func (*DynamicBytesFile) SetStat(context.Context, *vfs.Filesystem, *auth.Credent type DynamicBytesFD struct { vfs.FileDescriptionDefaultImpl vfs.DynamicBytesFileDescriptionImpl + vfs.LockFD vfsfd vfs.FileDescription inode Inode } // Init initializes a DynamicBytesFD. -func (fd *DynamicBytesFD) Init(m *vfs.Mount, d *vfs.Dentry, data vfs.DynamicBytesSource, flags uint32) error { +func (fd *DynamicBytesFD) Init(m *vfs.Mount, d *vfs.Dentry, data vfs.DynamicBytesSource, locks *vfs.FileLocks, flags uint32) error { + fd.LockFD.Init(locks) if err := fd.vfsfd.Init(fd, flags, m, d, &vfs.FileDescriptionOptions{}); err != nil { return err } @@ -97,12 +101,12 @@ func (fd *DynamicBytesFD) Seek(ctx context.Context, offset int64, whence int32) return fd.DynamicBytesFileDescriptionImpl.Seek(ctx, offset, whence) } -// Read implmenets vfs.FileDescriptionImpl.Read. +// Read implements vfs.FileDescriptionImpl.Read. func (fd *DynamicBytesFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { return fd.DynamicBytesFileDescriptionImpl.Read(ctx, dst, opts) } -// PRead implmenets vfs.FileDescriptionImpl.PRead. +// PRead implements vfs.FileDescriptionImpl.PRead. func (fd *DynamicBytesFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { return fd.DynamicBytesFileDescriptionImpl.PRead(ctx, dst, offset, opts) } @@ -123,7 +127,7 @@ func (fd *DynamicBytesFD) Release() {} // Stat implements vfs.FileDescriptionImpl.Stat. func (fd *DynamicBytesFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { fs := fd.vfsfd.VirtualDentry().Mount().Filesystem() - return fd.inode.Stat(fs, opts) + return fd.inode.Stat(ctx, fs, opts) } // SetStat implements vfs.FileDescriptionImpl.SetStat. @@ -131,3 +135,13 @@ func (fd *DynamicBytesFD) SetStat(context.Context, vfs.SetStatOptions) error { // DynamicBytesFiles are immutable. return syserror.EPERM } + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *DynamicBytesFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *DynamicBytesFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go index 8284e76a7..1d37ccb98 100644 --- a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go +++ b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go @@ -19,6 +19,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sentry/vfs" @@ -42,6 +43,7 @@ import ( type GenericDirectoryFD struct { vfs.FileDescriptionDefaultImpl vfs.DirectoryFileDescriptionDefaultImpl + vfs.LockFD vfsfd vfs.FileDescription children *OrderedChildren @@ -55,9 +57,9 @@ type GenericDirectoryFD struct { // NewGenericDirectoryFD creates a new GenericDirectoryFD and returns its // dentry. -func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildren, opts *vfs.OpenOptions) (*GenericDirectoryFD, error) { +func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions) (*GenericDirectoryFD, error) { fd := &GenericDirectoryFD{} - if err := fd.Init(children, opts); err != nil { + if err := fd.Init(children, locks, opts); err != nil { return nil, err } if err := fd.vfsfd.Init(fd, opts.Flags, m, d, &vfs.FileDescriptionOptions{}); err != nil { @@ -69,11 +71,12 @@ func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildre // Init initializes a GenericDirectoryFD. Use it when overriding // GenericDirectoryFD. Caller must call fd.VFSFileDescription.Init() with the // correct implementation. -func (fd *GenericDirectoryFD) Init(children *OrderedChildren, opts *vfs.OpenOptions) error { +func (fd *GenericDirectoryFD) Init(children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions) error { if vfs.AccessTypesForOpenFlags(opts)&vfs.MayWrite != 0 { // Can't open directories for writing. return syserror.EISDIR } + fd.LockFD.Init(locks) fd.children = children return nil } @@ -109,7 +112,7 @@ func (fd *GenericDirectoryFD) PWrite(ctx context.Context, src usermem.IOSequence return fd.DirectoryFileDescriptionDefaultImpl.PWrite(ctx, src, offset, opts) } -// Release implements vfs.FileDecriptionImpl.Release. +// Release implements vfs.FileDescriptionImpl.Release. func (fd *GenericDirectoryFD) Release() {} func (fd *GenericDirectoryFD) filesystem() *vfs.Filesystem { @@ -120,7 +123,7 @@ func (fd *GenericDirectoryFD) inode() Inode { return fd.vfsfd.VirtualDentry().Dentry().Impl().(*Dentry).inode } -// IterDirents implements vfs.FileDecriptionImpl.IterDirents. IterDirents holds +// IterDirents implements vfs.FileDescriptionImpl.IterDirents. IterDirents holds // o.mu when calling cb. func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback) error { fd.mu.Lock() @@ -129,7 +132,7 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent opts := vfs.StatOptions{Mask: linux.STATX_INO} // Handle ".". if fd.off == 0 { - stat, err := fd.inode().Stat(fd.filesystem(), opts) + stat, err := fd.inode().Stat(ctx, fd.filesystem(), opts) if err != nil { return err } @@ -149,7 +152,7 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent if fd.off == 1 { vfsd := fd.vfsfd.VirtualDentry().Dentry() parentInode := genericParentOrSelf(vfsd.Impl().(*Dentry)).inode - stat, err := parentInode.Stat(fd.filesystem(), opts) + stat, err := parentInode.Stat(ctx, fd.filesystem(), opts) if err != nil { return err } @@ -173,7 +176,7 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent childIdx := fd.off - 2 for it := fd.children.nthLocked(childIdx); it != nil; it = it.Next() { inode := it.Dentry.Impl().(*Dentry).inode - stat, err := inode.Stat(fd.filesystem(), opts) + stat, err := inode.Stat(ctx, fd.filesystem(), opts) if err != nil { return err } @@ -195,7 +198,7 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent return err } -// Seek implements vfs.FileDecriptionImpl.Seek. +// Seek implements vfs.FileDescriptionImpl.Seek. func (fd *GenericDirectoryFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { fd.mu.Lock() defer fd.mu.Unlock() @@ -223,7 +226,7 @@ func (fd *GenericDirectoryFD) Seek(ctx context.Context, offset int64, whence int func (fd *GenericDirectoryFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { fs := fd.filesystem() inode := fd.inode() - return inode.Stat(fs, opts) + return inode.Stat(ctx, fs, opts) } // SetStat implements vfs.FileDescriptionImpl.SetStat. @@ -232,3 +235,18 @@ func (fd *GenericDirectoryFD) SetStat(ctx context.Context, opts vfs.SetStatOptio inode := fd.vfsfd.VirtualDentry().Dentry().Impl().(*Dentry).inode return inode.SetStat(ctx, fd.filesystem(), creds, opts) } + +// Allocate implements vfs.FileDescriptionImpl.Allocate. +func (fd *GenericDirectoryFD) Allocate(ctx context.Context, mode, offset, length uint64) error { + return fd.DirectoryFileDescriptionDefaultImpl.Allocate(ctx, mode, offset, length) +} + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *GenericDirectoryFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *GenericDirectoryFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/kernfs/filesystem.go b/pkg/sentry/fsimpl/kernfs/filesystem.go index 4a12ae245..61a36cff9 100644 --- a/pkg/sentry/fsimpl/kernfs/filesystem.go +++ b/pkg/sentry/fsimpl/kernfs/filesystem.go @@ -35,7 +35,7 @@ import ( // Preconditions: Filesystem.mu must be locked for at least reading. !rp.Done(). // // Postcondition: Caller must call fs.processDeferredDecRefs*. -func (fs *Filesystem) stepExistingLocked(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry) (*vfs.Dentry, error) { +func (fs *Filesystem) stepExistingLocked(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, mayFollowSymlinks bool) (*vfs.Dentry, error) { d := vfsd.Impl().(*Dentry) if !d.isDir() { return nil, syserror.ENOTDIR @@ -81,7 +81,7 @@ afterSymlink: return nil, err } // Resolve any symlink at current path component. - if rp.ShouldFollowSymlink() && next.isSymlink() { + if mayFollowSymlinks && rp.ShouldFollowSymlink() && next.isSymlink() { targetVD, targetPathname, err := next.inode.Getlink(ctx, rp.Mount()) if err != nil { return nil, err @@ -152,7 +152,7 @@ func (fs *Filesystem) walkExistingLocked(ctx context.Context, rp *vfs.ResolvingP vfsd := rp.Start() for !rp.Done() { var err error - vfsd, err = fs.stepExistingLocked(ctx, rp, vfsd) + vfsd, err = fs.stepExistingLocked(ctx, rp, vfsd, true /* mayFollowSymlinks */) if err != nil { return nil, nil, err } @@ -178,7 +178,7 @@ func (fs *Filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.Resolving vfsd := rp.Start() for !rp.Final() { var err error - vfsd, err = fs.stepExistingLocked(ctx, rp, vfsd) + vfsd, err = fs.stepExistingLocked(ctx, rp, vfsd, true /* mayFollowSymlinks */) if err != nil { return nil, nil, err } @@ -449,7 +449,7 @@ afterTrailingSymlink: return nil, syserror.ENAMETOOLONG } // Determine whether or not we need to create a file. - childVFSD, err := fs.stepExistingLocked(ctx, rp, parentVFSD) + childVFSD, err := fs.stepExistingLocked(ctx, rp, parentVFSD, false /* mayFollowSymlinks */) if err == syserror.ENOENT { // Already checked for searchability above; now check for writability. if err := parentInode.CheckPermissions(ctx, rp.Credentials(), vfs.MayWrite); err != nil { @@ -684,7 +684,7 @@ func (fs *Filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf if err != nil { return linux.Statx{}, err } - return inode.Stat(fs.VFSFilesystem(), opts) + return inode.Stat(ctx, fs.VFSFilesystem(), opts) } // StatFSAt implements vfs.FilesystemImpl.StatFSAt. diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go index 982daa2e6..579e627f0 100644 --- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go +++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go @@ -243,7 +243,7 @@ func (a *InodeAttrs) Mode() linux.FileMode { // Stat partially implements Inode.Stat. Note that this function doesn't provide // all the stat fields, and the embedder should consider extending the result // with filesystem-specific fields. -func (a *InodeAttrs) Stat(*vfs.Filesystem, vfs.StatOptions) (linux.Statx, error) { +func (a *InodeAttrs) Stat(context.Context, *vfs.Filesystem, vfs.StatOptions) (linux.Statx, error) { var stat linux.Statx stat.Mask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_INO | linux.STATX_NLINK stat.DevMajor = a.devMajor @@ -267,7 +267,7 @@ func (a *InodeAttrs) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *aut if opts.Stat.Mask&^(linux.STATX_MODE|linux.STATX_UID|linux.STATX_GID) != 0 { return syserror.EPERM } - if err := vfs.CheckSetStat(ctx, creds, &opts.Stat, a.Mode(), auth.KUID(atomic.LoadUint32(&a.uid)), auth.KGID(atomic.LoadUint32(&a.gid))); err != nil { + if err := vfs.CheckSetStat(ctx, creds, &opts, a.Mode(), auth.KUID(atomic.LoadUint32(&a.uid)), auth.KGID(atomic.LoadUint32(&a.gid))); err != nil { return err } @@ -293,6 +293,8 @@ func (a *InodeAttrs) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *aut // inode numbers are immutable after node creation. // TODO(gvisor.dev/issue/1193): Implement other stat fields like timestamps. + // Also, STATX_SIZE will need some special handling, because read-only static + // files should return EIO for truncate operations. return nil } @@ -469,6 +471,8 @@ func (o *OrderedChildren) Unlink(ctx context.Context, name string, child *vfs.De if err := o.checkExistingLocked(name, child); err != nil { return err } + + // TODO(gvisor.dev/issue/3027): Check sticky bit before removing. o.removeLocked(name) return nil } @@ -516,6 +520,8 @@ func (o *OrderedChildren) Rename(ctx context.Context, oldname, newname string, c if err := o.checkExistingLocked(oldname, child); err != nil { return nil, err } + + // TODO(gvisor.dev/issue/3027): Check sticky bit before removing. replaced := dst.replaceChildLocked(newname, child) return replaced, nil } @@ -555,6 +561,8 @@ type StaticDirectory struct { InodeAttrs InodeNoDynamicLookup OrderedChildren + + locks vfs.FileLocks } var _ Inode = (*StaticDirectory)(nil) @@ -584,7 +592,7 @@ func (s *StaticDirectory) Init(creds *auth.Credentials, devMajor, devMinor uint3 // Open implements kernfs.Inode. func (s *StaticDirectory) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := NewGenericDirectoryFD(rp.Mount(), vfsd, &s.OrderedChildren, &opts) + fd, err := NewGenericDirectoryFD(rp.Mount(), vfsd, &s.OrderedChildren, &s.locks, &opts) if err != nil { return nil, err } diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go index a83151ad3..46f207664 100644 --- a/pkg/sentry/fsimpl/kernfs/kernfs.go +++ b/pkg/sentry/fsimpl/kernfs/kernfs.go @@ -225,9 +225,24 @@ func (d *Dentry) destroy() { } } +// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. +// +// Although Linux technically supports inotify on pseudo filesystems (inotify +// is implemented at the vfs layer), it is not particularly useful. It is left +// unimplemented until someone actually needs it. +func (d *Dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) {} + +// Watches implements vfs.DentryImpl.Watches. +func (d *Dentry) Watches() *vfs.Watches { + return nil +} + +// OnZeroWatches implements vfs.Dentry.OnZeroWatches. +func (d *Dentry) OnZeroWatches() {} + // InsertChild inserts child into the vfs dentry cache with the given name under // this dentry. This does not update the directory inode, so calling this on -// it's own isn't sufficient to insert a child into a directory. InsertChild +// its own isn't sufficient to insert a child into a directory. InsertChild // updates the link count on d if required. // // Precondition: d must represent a directory inode. @@ -331,7 +346,7 @@ type inodeMetadata interface { // Stat returns the metadata for this inode. This corresponds to // vfs.FilesystemImpl.StatAt. - Stat(fs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) + Stat(ctx context.Context, fs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) // SetStat updates the metadata for this inode. This corresponds to // vfs.FilesystemImpl.SetStatAt. Implementations are responsible for checking @@ -413,10 +428,10 @@ type inodeDynamicLookup interface { // IterDirents is used to iterate over dynamically created entries. It invokes // cb on each entry in the directory represented by the FileDescription. // 'offset' is the offset for the entire IterDirents call, which may include - // results from the caller. 'relOffset' is the offset inside the entries - // returned by this IterDirents invocation. In other words, - // 'offset+relOffset+1' is the value that should be set in vfs.Dirent.NextOff, - // while 'relOffset' is the place where iteration should start from. + // results from the caller (e.g. "." and ".."). 'relOffset' is the offset + // inside the entries returned by this IterDirents invocation. In other words, + // 'offset' should be used to calculate each vfs.Dirent.NextOff as well as + // the return value, while 'relOffset' is the place to start iteration. IterDirents(ctx context.Context, callback vfs.IterDirentsCallback, offset, relOffset int64) (newOffset int64, err error) } diff --git a/pkg/sentry/fsimpl/kernfs/kernfs_test.go b/pkg/sentry/fsimpl/kernfs/kernfs_test.go index 412cf6ac9..dc407eb1d 100644 --- a/pkg/sentry/fsimpl/kernfs/kernfs_test.go +++ b/pkg/sentry/fsimpl/kernfs/kernfs_test.go @@ -100,8 +100,10 @@ type readonlyDir struct { kernfs.InodeNotSymlink kernfs.InodeNoDynamicLookup kernfs.InodeDirectoryNoNewChildren - kernfs.OrderedChildren + + locks vfs.FileLocks + dentry kernfs.Dentry } @@ -117,7 +119,7 @@ func (fs *filesystem) newReadonlyDir(creds *auth.Credentials, mode linux.FileMod } func (d *readonlyDir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts) if err != nil { return nil, err } @@ -128,10 +130,12 @@ type dir struct { attrs kernfs.InodeNotSymlink kernfs.InodeNoDynamicLookup + kernfs.OrderedChildren + + locks vfs.FileLocks fs *filesystem dentry kernfs.Dentry - kernfs.OrderedChildren } func (fs *filesystem) newDir(creds *auth.Credentials, mode linux.FileMode, contents map[string]*kernfs.Dentry) *kernfs.Dentry { @@ -147,7 +151,7 @@ func (fs *filesystem) newDir(creds *auth.Credentials, mode linux.FileMode, conte } func (d *dir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts) if err != nil { return nil, err } diff --git a/pkg/sentry/fsimpl/overlay/BUILD b/pkg/sentry/fsimpl/overlay/BUILD new file mode 100644 index 000000000..8cf5b35d3 --- /dev/null +++ b/pkg/sentry/fsimpl/overlay/BUILD @@ -0,0 +1,41 @@ +load("//tools:defs.bzl", "go_library") +load("//tools/go_generics:defs.bzl", "go_template_instance") + +licenses(["notice"]) + +go_template_instance( + name = "fstree", + out = "fstree.go", + package = "overlay", + prefix = "generic", + template = "//pkg/sentry/vfs/genericfstree:generic_fstree", + types = { + "Dentry": "dentry", + }, +) + +go_library( + name = "overlay", + srcs = [ + "copy_up.go", + "directory.go", + "filesystem.go", + "fstree.go", + "non_directory.go", + "overlay.go", + ], + visibility = ["//pkg/sentry:internal"], + deps = [ + "//pkg/abi/linux", + "//pkg/context", + "//pkg/fspath", + "//pkg/sentry/fs/lock", + "//pkg/sentry/kernel/auth", + "//pkg/sentry/memmap", + "//pkg/sentry/socket/unix/transport", + "//pkg/sentry/vfs", + "//pkg/sync", + "//pkg/syserror", + "//pkg/usermem", + ], +) diff --git a/pkg/sentry/fsimpl/overlay/copy_up.go b/pkg/sentry/fsimpl/overlay/copy_up.go new file mode 100644 index 000000000..8f8dcfafe --- /dev/null +++ b/pkg/sentry/fsimpl/overlay/copy_up.go @@ -0,0 +1,262 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package overlay + +import ( + "fmt" + "io" + "sync/atomic" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/fspath" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" +) + +func (d *dentry) isCopiedUp() bool { + return atomic.LoadUint32(&d.copiedUp) != 0 +} + +// copyUpLocked ensures that d exists on the upper layer, i.e. d.upperVD.Ok(). +// +// Preconditions: filesystem.renameMu must be locked. +func (d *dentry) copyUpLocked(ctx context.Context) error { + // Fast path. + if d.isCopiedUp() { + return nil + } + + ftype := atomic.LoadUint32(&d.mode) & linux.S_IFMT + switch ftype { + case linux.S_IFREG, linux.S_IFDIR, linux.S_IFLNK, linux.S_IFBLK, linux.S_IFCHR: + // Can be copied-up. + default: + // Can't be copied-up. + return syserror.EPERM + } + + // Ensure that our parent directory is copied-up. + if d.parent == nil { + // d is a filesystem root with no upper layer. + return syserror.EROFS + } + if err := d.parent.copyUpLocked(ctx); err != nil { + return err + } + + d.copyMu.Lock() + defer d.copyMu.Unlock() + if d.upperVD.Ok() { + // Raced with another call to d.copyUpLocked(). + return nil + } + if d.vfsd.IsDead() { + // Raced with deletion of d. + return syserror.ENOENT + } + + // Perform copy-up. + vfsObj := d.fs.vfsfs.VirtualFilesystem() + newpop := vfs.PathOperation{ + Root: d.parent.upperVD, + Start: d.parent.upperVD, + Path: fspath.Parse(d.name), + } + cleanupUndoCopyUp := func() { + var err error + if ftype == linux.S_IFDIR { + err = vfsObj.RmdirAt(ctx, d.fs.creds, &newpop) + } else { + err = vfsObj.UnlinkAt(ctx, d.fs.creds, &newpop) + } + if err != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer file after copy-up error: %v", err) + } + } + switch ftype { + case linux.S_IFREG: + oldFD, err := vfsObj.OpenAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: d.lowerVDs[0], + Start: d.lowerVDs[0], + }, &vfs.OpenOptions{ + Flags: linux.O_RDONLY, + }) + if err != nil { + return err + } + defer oldFD.DecRef() + newFD, err := vfsObj.OpenAt(ctx, d.fs.creds, &newpop, &vfs.OpenOptions{ + Flags: linux.O_WRONLY | linux.O_CREAT | linux.O_EXCL, + Mode: linux.FileMode(d.mode &^ linux.S_IFMT), + }) + if err != nil { + return err + } + defer newFD.DecRef() + bufIOSeq := usermem.BytesIOSequence(make([]byte, 32*1024)) // arbitrary buffer size + for { + readN, readErr := oldFD.Read(ctx, bufIOSeq, vfs.ReadOptions{}) + if readErr != nil && readErr != io.EOF { + cleanupUndoCopyUp() + return readErr + } + total := int64(0) + for total < readN { + writeN, writeErr := newFD.Write(ctx, bufIOSeq.DropFirst64(total), vfs.WriteOptions{}) + total += writeN + if writeErr != nil { + cleanupUndoCopyUp() + return writeErr + } + } + if readErr == io.EOF { + break + } + } + if err := newFD.SetStat(ctx, vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: d.uid, + GID: d.gid, + }, + }); err != nil { + cleanupUndoCopyUp() + return err + } + d.upperVD = newFD.VirtualDentry() + d.upperVD.IncRef() + + case linux.S_IFDIR: + if err := vfsObj.MkdirAt(ctx, d.fs.creds, &newpop, &vfs.MkdirOptions{ + Mode: linux.FileMode(d.mode &^ linux.S_IFMT), + }); err != nil { + return err + } + if err := vfsObj.SetStatAt(ctx, d.fs.creds, &newpop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: d.uid, + GID: d.gid, + }, + }); err != nil { + cleanupUndoCopyUp() + return err + } + upperVD, err := vfsObj.GetDentryAt(ctx, d.fs.creds, &newpop, &vfs.GetDentryOptions{}) + if err != nil { + cleanupUndoCopyUp() + return err + } + d.upperVD = upperVD + + case linux.S_IFLNK: + target, err := vfsObj.ReadlinkAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: d.lowerVDs[0], + Start: d.lowerVDs[0], + }) + if err != nil { + return err + } + if err := vfsObj.SymlinkAt(ctx, d.fs.creds, &newpop, target); err != nil { + return err + } + if err := vfsObj.SetStatAt(ctx, d.fs.creds, &newpop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID, + Mode: uint16(d.mode), + UID: d.uid, + GID: d.gid, + }, + }); err != nil { + cleanupUndoCopyUp() + return err + } + upperVD, err := vfsObj.GetDentryAt(ctx, d.fs.creds, &newpop, &vfs.GetDentryOptions{}) + if err != nil { + cleanupUndoCopyUp() + return err + } + d.upperVD = upperVD + + case linux.S_IFBLK, linux.S_IFCHR: + lowerStat, err := vfsObj.StatAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: d.lowerVDs[0], + Start: d.lowerVDs[0], + }, &vfs.StatOptions{}) + if err != nil { + return err + } + if err := vfsObj.MknodAt(ctx, d.fs.creds, &newpop, &vfs.MknodOptions{ + Mode: linux.FileMode(d.mode), + DevMajor: lowerStat.RdevMajor, + DevMinor: lowerStat.RdevMinor, + }); err != nil { + return err + } + if err := vfsObj.SetStatAt(ctx, d.fs.creds, &newpop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: d.uid, + GID: d.gid, + }, + }); err != nil { + cleanupUndoCopyUp() + return err + } + upperVD, err := vfsObj.GetDentryAt(ctx, d.fs.creds, &newpop, &vfs.GetDentryOptions{}) + if err != nil { + cleanupUndoCopyUp() + return err + } + d.upperVD = upperVD + + default: + // Should have rejected this at the beginning of this function? + panic(fmt.Sprintf("unexpected file type %o", ftype)) + } + + // TODO(gvisor.dev/issue/1199): copy up xattrs + + // Update the dentry's device and inode numbers (except for directories, + // for which these remain overlay-assigned). + if ftype != linux.S_IFDIR { + upperStat, err := vfsObj.StatAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: d.upperVD, + Start: d.upperVD, + }, &vfs.StatOptions{ + Mask: linux.STATX_INO, + }) + if err != nil { + d.upperVD.DecRef() + d.upperVD = vfs.VirtualDentry{} + cleanupUndoCopyUp() + return err + } + if upperStat.Mask&linux.STATX_INO == 0 { + d.upperVD.DecRef() + d.upperVD = vfs.VirtualDentry{} + cleanupUndoCopyUp() + return syserror.EREMOTE + } + atomic.StoreUint32(&d.devMajor, upperStat.DevMajor) + atomic.StoreUint32(&d.devMinor, upperStat.DevMinor) + atomic.StoreUint64(&d.ino, upperStat.Ino) + } + + atomic.StoreUint32(&d.copiedUp, 1) + return nil +} diff --git a/pkg/sentry/fsimpl/overlay/directory.go b/pkg/sentry/fsimpl/overlay/directory.go new file mode 100644 index 000000000..f5c2462a5 --- /dev/null +++ b/pkg/sentry/fsimpl/overlay/directory.go @@ -0,0 +1,287 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package overlay + +import ( + "sync/atomic" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/fspath" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" +) + +func (d *dentry) isDir() bool { + return atomic.LoadUint32(&d.mode)&linux.S_IFMT == linux.S_IFDIR +} + +// Preconditions: d.dirMu must be locked. d.isDir(). +func (d *dentry) collectWhiteoutsForRmdirLocked(ctx context.Context) (map[string]bool, error) { + vfsObj := d.fs.vfsfs.VirtualFilesystem() + var readdirErr error + whiteouts := make(map[string]bool) + var maybeWhiteouts []string + d.iterLayers(func(layerVD vfs.VirtualDentry, isUpper bool) bool { + layerFD, err := vfsObj.OpenAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + }, &vfs.OpenOptions{ + Flags: linux.O_RDONLY | linux.O_DIRECTORY, + }) + if err != nil { + readdirErr = err + return false + } + defer layerFD.DecRef() + + // Reuse slice allocated for maybeWhiteouts from a previous layer to + // reduce allocations. + maybeWhiteouts = maybeWhiteouts[:0] + if err := layerFD.IterDirents(ctx, vfs.IterDirentsCallbackFunc(func(dirent vfs.Dirent) error { + if dirent.Name == "." || dirent.Name == ".." { + return nil + } + if _, ok := whiteouts[dirent.Name]; ok { + // This file has been whited-out in a previous layer. + return nil + } + if dirent.Type == linux.DT_CHR { + // We have to determine if this is a whiteout, which doesn't + // count against the directory's emptiness. However, we can't + // do so while holding locks held by layerFD.IterDirents(). + maybeWhiteouts = append(maybeWhiteouts, dirent.Name) + return nil + } + // Non-whiteout file in the directory prevents rmdir. + return syserror.ENOTEMPTY + })); err != nil { + readdirErr = err + return false + } + + for _, maybeWhiteoutName := range maybeWhiteouts { + stat, err := vfsObj.StatAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + Path: fspath.Parse(maybeWhiteoutName), + }, &vfs.StatOptions{}) + if err != nil { + readdirErr = err + return false + } + if stat.RdevMajor != 0 || stat.RdevMinor != 0 { + // This file is a real character device, not a whiteout. + readdirErr = syserror.ENOTEMPTY + return false + } + whiteouts[maybeWhiteoutName] = isUpper + } + // Continue iteration since we haven't found any non-whiteout files in + // this directory yet. + return true + }) + return whiteouts, readdirErr +} + +type directoryFD struct { + fileDescription + vfs.DirectoryFileDescriptionDefaultImpl + vfs.DentryMetadataFileDescriptionImpl + + mu sync.Mutex + off int64 + dirents []vfs.Dirent +} + +// Release implements vfs.FileDescriptionImpl.Release. +func (fd *directoryFD) Release() { +} + +// IterDirents implements vfs.FileDescriptionImpl.IterDirents. +func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback) error { + fd.mu.Lock() + defer fd.mu.Unlock() + + d := fd.dentry() + if fd.dirents == nil { + ds, err := d.getDirents(ctx) + if err != nil { + return err + } + fd.dirents = ds + } + + for fd.off < int64(len(fd.dirents)) { + if err := cb.Handle(fd.dirents[fd.off]); err != nil { + return err + } + fd.off++ + } + return nil +} + +// Preconditions: d.isDir(). +func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) { + d.fs.renameMu.RLock() + defer d.fs.renameMu.RUnlock() + d.dirMu.Lock() + defer d.dirMu.Unlock() + + if d.dirents != nil { + return d.dirents, nil + } + + parent := genericParentOrSelf(d) + dirents := []vfs.Dirent{ + { + Name: ".", + Type: linux.DT_DIR, + Ino: d.ino, + NextOff: 1, + }, + { + Name: "..", + Type: uint8(atomic.LoadUint32(&parent.mode) >> 12), + Ino: parent.ino, + NextOff: 2, + }, + } + + // Merge dirents from all layers comprising this directory. + vfsObj := d.fs.vfsfs.VirtualFilesystem() + var readdirErr error + prevDirents := make(map[string]struct{}) + var maybeWhiteouts []vfs.Dirent + d.iterLayers(func(layerVD vfs.VirtualDentry, isUpper bool) bool { + layerFD, err := vfsObj.OpenAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + }, &vfs.OpenOptions{ + Flags: linux.O_RDONLY | linux.O_DIRECTORY, + }) + if err != nil { + readdirErr = err + return false + } + defer layerFD.DecRef() + + // Reuse slice allocated for maybeWhiteouts from a previous layer to + // reduce allocations. + maybeWhiteouts = maybeWhiteouts[:0] + if err := layerFD.IterDirents(ctx, vfs.IterDirentsCallbackFunc(func(dirent vfs.Dirent) error { + if dirent.Name == "." || dirent.Name == ".." { + return nil + } + if _, ok := prevDirents[dirent.Name]; ok { + // This file is hidden by, or merged with, another file with + // the same name in a previous layer. + return nil + } + prevDirents[dirent.Name] = struct{}{} + if dirent.Type == linux.DT_CHR { + // We can't determine if this file is a whiteout while holding + // locks held by layerFD.IterDirents(). + maybeWhiteouts = append(maybeWhiteouts, dirent) + return nil + } + dirent.NextOff = int64(len(dirents) + 1) + dirents = append(dirents, dirent) + return nil + })); err != nil { + readdirErr = err + return false + } + + for _, dirent := range maybeWhiteouts { + stat, err := vfsObj.StatAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + Path: fspath.Parse(dirent.Name), + }, &vfs.StatOptions{}) + if err != nil { + readdirErr = err + return false + } + if stat.RdevMajor == 0 && stat.RdevMinor == 0 { + // This file is a whiteout; don't emit a dirent for it. + continue + } + dirent.NextOff = int64(len(dirents) + 1) + dirents = append(dirents, dirent) + } + return true + }) + if readdirErr != nil { + return nil, readdirErr + } + + // Cache dirents for future directoryFDs. + d.dirents = dirents + return dirents, nil +} + +// Seek implements vfs.FileDescriptionImpl.Seek. +func (fd *directoryFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + fd.mu.Lock() + defer fd.mu.Unlock() + + switch whence { + case linux.SEEK_SET: + if offset < 0 { + return 0, syserror.EINVAL + } + if offset == 0 { + // Ensure that the next call to fd.IterDirents() calls + // fd.dentry().getDirents(). + fd.dirents = nil + } + fd.off = offset + return fd.off, nil + case linux.SEEK_CUR: + offset += fd.off + if offset < 0 { + return 0, syserror.EINVAL + } + // Don't clear fd.dirents in this case, even if offset == 0. + fd.off = offset + return fd.off, nil + default: + return 0, syserror.EINVAL + } +} + +// Sync implements vfs.FileDescriptionImpl.Sync. Forwards sync to the upper +// layer, if there is one. The lower layer doesn't need to sync because it +// never changes. +func (fd *directoryFD) Sync(ctx context.Context) error { + d := fd.dentry() + if !d.isCopiedUp() { + return nil + } + vfsObj := d.fs.vfsfs.VirtualFilesystem() + pop := vfs.PathOperation{ + Root: d.upperVD, + Start: d.upperVD, + } + upperFD, err := vfsObj.OpenAt(ctx, d.fs.creds, &pop, &vfs.OpenOptions{Flags: linux.O_RDONLY | linux.O_DIRECTORY}) + if err != nil { + return err + } + err = upperFD.Sync(ctx) + upperFD.DecRef() + return err +} diff --git a/pkg/sentry/fsimpl/overlay/filesystem.go b/pkg/sentry/fsimpl/overlay/filesystem.go new file mode 100644 index 000000000..6b705e955 --- /dev/null +++ b/pkg/sentry/fsimpl/overlay/filesystem.go @@ -0,0 +1,1364 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package overlay + +import ( + "sync/atomic" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/fspath" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/socket/unix/transport" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" +) + +// _OVL_XATTR_OPAQUE is an extended attribute key whose value is set to "y" for +// opaque directories. +// Linux: fs/overlayfs/overlayfs.h:OVL_XATTR_OPAQUE +const _OVL_XATTR_OPAQUE = "trusted.overlay.opaque" + +func isWhiteout(stat *linux.Statx) bool { + return stat.Mode&linux.S_IFMT == linux.S_IFCHR && stat.RdevMajor == 0 && stat.RdevMinor == 0 +} + +// Sync implements vfs.FilesystemImpl.Sync. +func (fs *filesystem) Sync(ctx context.Context) error { + if fs.opts.UpperRoot.Ok() { + return fs.opts.UpperRoot.Mount().Filesystem().Impl().Sync(ctx) + } + return nil +} + +var dentrySlicePool = sync.Pool{ + New: func() interface{} { + ds := make([]*dentry, 0, 4) // arbitrary non-zero initial capacity + return &ds + }, +} + +func appendDentry(ds *[]*dentry, d *dentry) *[]*dentry { + if ds == nil { + ds = dentrySlicePool.Get().(*[]*dentry) + } + *ds = append(*ds, d) + return ds +} + +// Preconditions: ds != nil. +func putDentrySlice(ds *[]*dentry) { + // Allow dentries to be GC'd. + for i := range *ds { + (*ds)[i] = nil + } + *ds = (*ds)[:0] + dentrySlicePool.Put(ds) +} + +// renameMuRUnlockAndCheckDrop calls fs.renameMu.RUnlock(), then calls +// dentry.checkDropLocked on all dentries in *ds with fs.renameMu locked for +// writing. +// +// ds is a pointer-to-pointer since defer evaluates its arguments immediately, +// but dentry slices are allocated lazily, and it's much easier to say "defer +// fs.renameMuRUnlockAndCheckDrop(&ds)" than "defer func() { +// fs.renameMuRUnlockAndCheckDrop(ds) }()" to work around this. +func (fs *filesystem) renameMuRUnlockAndCheckDrop(ds **[]*dentry) { + fs.renameMu.RUnlock() + if *ds == nil { + return + } + if len(**ds) != 0 { + fs.renameMu.Lock() + for _, d := range **ds { + d.checkDropLocked() + } + fs.renameMu.Unlock() + } + putDentrySlice(*ds) +} + +func (fs *filesystem) renameMuUnlockAndCheckDrop(ds **[]*dentry) { + if *ds == nil { + fs.renameMu.Unlock() + return + } + for _, d := range **ds { + d.checkDropLocked() + } + fs.renameMu.Unlock() + putDentrySlice(*ds) +} + +// stepLocked resolves rp.Component() to an existing file, starting from the +// given directory. +// +// Dentries which may have a reference count of zero, and which therefore +// should be dropped once traversal is complete, are appended to ds. +// +// Preconditions: fs.renameMu must be locked. d.dirMu must be locked. +// !rp.Done(). +func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, mayFollowSymlinks bool, ds **[]*dentry) (*dentry, error) { + if !d.isDir() { + return nil, syserror.ENOTDIR + } + if err := d.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil { + return nil, err + } +afterSymlink: + name := rp.Component() + if name == "." { + rp.Advance() + return d, nil + } + if name == ".." { + if isRoot, err := rp.CheckRoot(&d.vfsd); err != nil { + return nil, err + } else if isRoot || d.parent == nil { + rp.Advance() + return d, nil + } + if err := rp.CheckMount(&d.parent.vfsd); err != nil { + return nil, err + } + rp.Advance() + return d.parent, nil + } + child, err := fs.getChildLocked(ctx, d, name, ds) + if err != nil { + return nil, err + } + if err := rp.CheckMount(&child.vfsd); err != nil { + return nil, err + } + if child.isSymlink() && mayFollowSymlinks && rp.ShouldFollowSymlink() { + target, err := child.readlink(ctx) + if err != nil { + return nil, err + } + if err := rp.HandleSymlink(target); err != nil { + return nil, err + } + goto afterSymlink // don't check the current directory again + } + rp.Advance() + return child, nil +} + +// Preconditions: fs.renameMu must be locked. d.dirMu must be locked. +func (fs *filesystem) getChildLocked(ctx context.Context, parent *dentry, name string, ds **[]*dentry) (*dentry, error) { + if child, ok := parent.children[name]; ok { + return child, nil + } + child, err := fs.lookupLocked(ctx, parent, name) + if err != nil { + return nil, err + } + if parent.children == nil { + parent.children = make(map[string]*dentry) + } + parent.children[name] = child + // child's refcount is initially 0, so it may be dropped after traversal. + *ds = appendDentry(*ds, child) + return child, nil +} + +// Preconditions: fs.renameMu must be locked. parent.dirMu must be locked. +func (fs *filesystem) lookupLocked(ctx context.Context, parent *dentry, name string) (*dentry, error) { + childPath := fspath.Parse(name) + child := fs.newDentry() + existsOnAnyLayer := false + var lookupErr error + + vfsObj := fs.vfsfs.VirtualFilesystem() + parent.iterLayers(func(parentVD vfs.VirtualDentry, isUpper bool) bool { + childVD, err := vfsObj.GetDentryAt(ctx, fs.creds, &vfs.PathOperation{ + Root: parentVD, + Start: parentVD, + Path: childPath, + }, &vfs.GetDentryOptions{}) + if err == syserror.ENOENT || err == syserror.ENAMETOOLONG { + // The file doesn't exist on this layer. Proceed to the next one. + return true + } + if err != nil { + lookupErr = err + return false + } + + mask := uint32(linux.STATX_TYPE) + if !existsOnAnyLayer { + // Mode, UID, GID, and (for non-directories) inode number come from + // the topmost layer on which the file exists. + mask |= linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_INO + } + stat, err := vfsObj.StatAt(ctx, fs.creds, &vfs.PathOperation{ + Root: childVD, + Start: childVD, + }, &vfs.StatOptions{ + Mask: mask, + }) + if err != nil { + lookupErr = err + return false + } + if stat.Mask&mask != mask { + lookupErr = syserror.EREMOTE + return false + } + + if isWhiteout(&stat) { + // This is a whiteout, so it "doesn't exist" on this layer, and + // layers below this one are ignored. + return false + } + isDir := stat.Mode&linux.S_IFMT == linux.S_IFDIR + if existsOnAnyLayer && !isDir { + // Directories are not merged with non-directory files from lower + // layers; instead, layers including and below the first + // non-directory file are ignored. (This file must be a directory + // on previous layers, since lower layers aren't searched for + // non-directory files.) + return false + } + + // Update child to include this layer. + if isUpper { + child.upperVD = childVD + child.copiedUp = 1 + } else { + child.lowerVDs = append(child.lowerVDs, childVD) + } + if !existsOnAnyLayer { + existsOnAnyLayer = true + child.mode = uint32(stat.Mode) + child.uid = stat.UID + child.gid = stat.GID + child.devMajor = stat.DevMajor + child.devMinor = stat.DevMinor + child.ino = stat.Ino + } + + // For non-directory files, only the topmost layer that contains a file + // matters. + if !isDir { + return false + } + + // Directories are merged with directories from lower layers if they + // are not explicitly opaque. + opaqueVal, err := vfsObj.GetxattrAt(ctx, fs.creds, &vfs.PathOperation{ + Root: childVD, + Start: childVD, + }, &vfs.GetxattrOptions{ + Name: _OVL_XATTR_OPAQUE, + Size: 1, + }) + return !(err == nil && opaqueVal == "y") + }) + + if lookupErr != nil { + child.destroyLocked() + return nil, lookupErr + } + if !existsOnAnyLayer { + child.destroyLocked() + return nil, syserror.ENOENT + } + + // Device and inode numbers were copied from the topmost layer above; + // override them if necessary. + if child.isDir() { + child.devMajor = linux.UNNAMED_MAJOR + child.devMinor = fs.dirDevMinor + child.ino = fs.newDirIno() + } else if !child.upperVD.Ok() { + child.devMajor = linux.UNNAMED_MAJOR + child.devMinor = fs.lowerDevMinors[child.lowerVDs[0].Mount().Filesystem()] + } + + parent.IncRef() + child.parent = parent + child.name = name + return child, nil +} + +// lookupLayerLocked is similar to lookupLocked, but only returns information +// about the file rather than a dentry. +// +// Preconditions: fs.renameMu must be locked. parent.dirMu must be locked. +func (fs *filesystem) lookupLayerLocked(ctx context.Context, parent *dentry, name string) (lookupLayer, error) { + childPath := fspath.Parse(name) + lookupLayer := lookupLayerNone + var lookupErr error + + parent.iterLayers(func(parentVD vfs.VirtualDentry, isUpper bool) bool { + stat, err := fs.vfsfs.VirtualFilesystem().StatAt(ctx, fs.creds, &vfs.PathOperation{ + Root: parentVD, + Start: parentVD, + Path: childPath, + }, &vfs.StatOptions{ + Mask: linux.STATX_TYPE, + }) + if err == syserror.ENOENT || err == syserror.ENAMETOOLONG { + // The file doesn't exist on this layer. Proceed to the next + // one. + return true + } + if err != nil { + lookupErr = err + return false + } + if stat.Mask&linux.STATX_TYPE == 0 { + // Linux's overlayfs tends to return EREMOTE in cases where a file + // is unusable for reasons that are not better captured by another + // errno. + lookupErr = syserror.EREMOTE + return false + } + if isWhiteout(&stat) { + // This is a whiteout, so it "doesn't exist" on this layer, and + // layers below this one are ignored. + if isUpper { + lookupLayer = lookupLayerUpperWhiteout + } + return false + } + // The file exists; we can stop searching. + if isUpper { + lookupLayer = lookupLayerUpper + } else { + lookupLayer = lookupLayerLower + } + return false + }) + + return lookupLayer, lookupErr +} + +type lookupLayer int + +const ( + // lookupLayerNone indicates that no file exists at the given path on the + // upper layer, and is either whited out or does not exist on lower layers. + // Therefore, the file does not exist in the overlay filesystem, and file + // creation may proceed normally (if an upper layer exists). + lookupLayerNone lookupLayer = iota + + // lookupLayerLower indicates that no file exists at the given path on the + // upper layer, but exists on a lower layer. Therefore, the file exists in + // the overlay filesystem, but must be copied-up before mutation. + lookupLayerLower + + // lookupLayerUpper indicates that a non-whiteout file exists at the given + // path on the upper layer. Therefore, the file exists in the overlay + // filesystem, and is already copied-up. + lookupLayerUpper + + // lookupLayerUpperWhiteout indicates that a whiteout exists at the given + // path on the upper layer. Therefore, the file does not exist in the + // overlay filesystem, and file creation must remove the whiteout before + // proceeding. + lookupLayerUpperWhiteout +) + +func (ll lookupLayer) existsInOverlay() bool { + return ll == lookupLayerLower || ll == lookupLayerUpper +} + +// walkParentDirLocked resolves all but the last path component of rp to an +// existing directory, starting from the given directory (which is usually +// rp.Start().Impl().(*dentry)). It does not check that the returned directory +// is searchable by the provider of rp. +// +// Preconditions: fs.renameMu must be locked. !rp.Done(). +func (fs *filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, ds **[]*dentry) (*dentry, error) { + for !rp.Final() { + d.dirMu.Lock() + next, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds) + d.dirMu.Unlock() + if err != nil { + return nil, err + } + d = next + } + if !d.isDir() { + return nil, syserror.ENOTDIR + } + return d, nil +} + +// resolveLocked resolves rp to an existing file. +// +// Preconditions: fs.renameMu must be locked. +func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath, ds **[]*dentry) (*dentry, error) { + d := rp.Start().Impl().(*dentry) + for !rp.Done() { + d.dirMu.Lock() + next, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds) + d.dirMu.Unlock() + if err != nil { + return nil, err + } + d = next + } + if rp.MustBeDir() && !d.isDir() { + return nil, syserror.ENOTDIR + } + return d, nil +} + +// doCreateAt checks that creating a file at rp is permitted, then invokes +// create to do so. +// +// Preconditions: !rp.Done(). For the final path component in rp, +// !rp.ShouldFollowSymlink(). +func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool, create func(parent *dentry, name string, haveUpperWhiteout bool) error) error { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + start := rp.Start().Impl().(*dentry) + parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds) + if err != nil { + return err + } + if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil { + return err + } + name := rp.Component() + if name == "." || name == ".." { + return syserror.EEXIST + } + if !dir && rp.MustBeDir() { + return syserror.ENOENT + } + if parent.vfsd.IsDead() { + return syserror.ENOENT + } + mnt := rp.Mount() + if err := mnt.CheckBeginWrite(); err != nil { + return err + } + defer mnt.EndWrite() + parent.dirMu.Lock() + defer parent.dirMu.Unlock() + + // Determine if a file already exists at name. + if _, ok := parent.children[name]; ok { + return syserror.EEXIST + } + childLayer, err := fs.lookupLayerLocked(ctx, parent, name) + if err != nil { + return err + } + if childLayer.existsInOverlay() { + return syserror.EEXIST + } + + // Ensure that the parent directory is copied-up so that we can create the + // new file in the upper layer. + if err := parent.copyUpLocked(ctx); err != nil { + return err + } + + // Finally create the new file. + if err := create(parent, name, childLayer == lookupLayerUpperWhiteout); err != nil { + return err + } + parent.dirents = nil + return nil +} + +// Preconditions: pop's parent directory has been copied up. +func (fs *filesystem) createWhiteout(ctx context.Context, vfsObj *vfs.VirtualFilesystem, pop *vfs.PathOperation) error { + return vfsObj.MknodAt(ctx, fs.creds, pop, &vfs.MknodOptions{ + Mode: linux.S_IFCHR, // permissions == include/linux/fs.h:WHITEOUT_MODE == 0 + // DevMajor == DevMinor == 0, from include/linux/fs.h:WHITEOUT_DEV + }) +} + +func (fs *filesystem) cleanupRecreateWhiteout(ctx context.Context, vfsObj *vfs.VirtualFilesystem, pop *vfs.PathOperation) { + if err := fs.createWhiteout(ctx, vfsObj, pop); err != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to recreate whiteout after failed file creation: %v", err) + } +} + +// AccessAt implements vfs.Filesystem.Impl.AccessAt. +func (fs *filesystem) AccessAt(ctx context.Context, rp *vfs.ResolvingPath, creds *auth.Credentials, ats vfs.AccessTypes) error { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + d, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return err + } + return d.checkPermissions(creds, ats) +} + +// BoundEndpointAt implements vfs.FilesystemImpl.BoundEndpointAt. +func (fs *filesystem) BoundEndpointAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.BoundEndpointOptions) (transport.BoundEndpoint, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + d, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return nil, err + } + if err := d.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil { + return nil, err + } + layerVD := d.topLayer() + return fs.vfsfs.VirtualFilesystem().BoundEndpointAt(ctx, fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + }, &opts) +} + +// GetDentryAt implements vfs.FilesystemImpl.GetDentryAt. +func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetDentryOptions) (*vfs.Dentry, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + d, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return nil, err + } + if opts.CheckSearchable { + if !d.isDir() { + return nil, syserror.ENOTDIR + } + if err := d.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil { + return nil, err + } + } + d.IncRef() + return &d.vfsd, nil +} + +// GetParentDentryAt implements vfs.FilesystemImpl.GetParentDentryAt. +func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + start := rp.Start().Impl().(*dentry) + d, err := fs.walkParentDirLocked(ctx, rp, start, &ds) + if err != nil { + return nil, err + } + d.IncRef() + return &d.vfsd, nil +} + +// LinkAt implements vfs.FilesystemImpl.LinkAt. +func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error { + return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error { + if rp.Mount() != vd.Mount() { + return syserror.EXDEV + } + old := vd.Dentry().Impl().(*dentry) + if old.isDir() { + return syserror.EPERM + } + if err := old.copyUpLocked(ctx); err != nil { + return err + } + vfsObj := fs.vfsfs.VirtualFilesystem() + newpop := vfs.PathOperation{ + Root: parent.upperVD, + Start: parent.upperVD, + Path: fspath.Parse(childName), + } + if haveUpperWhiteout { + if err := vfsObj.UnlinkAt(ctx, fs.creds, &newpop); err != nil { + return err + } + } + if err := vfsObj.LinkAt(ctx, fs.creds, &vfs.PathOperation{ + Root: old.upperVD, + Start: old.upperVD, + }, &newpop); err != nil { + if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &newpop) + } + return err + } + creds := rp.Credentials() + if err := vfsObj.SetStatAt(ctx, fs.creds, &newpop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: uint32(creds.EffectiveKUID), + GID: uint32(creds.EffectiveKGID), + }, + }); err != nil { + if cleanupErr := vfsObj.UnlinkAt(ctx, fs.creds, &newpop); cleanupErr != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer file after LinkAt metadata update failure: %v", cleanupErr) + } else if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &newpop) + } + return err + } + return nil + }) +} + +// MkdirAt implements vfs.FilesystemImpl.MkdirAt. +func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error { + return fs.doCreateAt(ctx, rp, true /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error { + vfsObj := fs.vfsfs.VirtualFilesystem() + pop := vfs.PathOperation{ + Root: parent.upperVD, + Start: parent.upperVD, + Path: fspath.Parse(childName), + } + if haveUpperWhiteout { + if err := vfsObj.UnlinkAt(ctx, fs.creds, &pop); err != nil { + return err + } + } + if err := vfsObj.MkdirAt(ctx, fs.creds, &pop, &opts); err != nil { + if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return err + } + creds := rp.Credentials() + if err := vfsObj.SetStatAt(ctx, fs.creds, &pop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: uint32(creds.EffectiveKUID), + GID: uint32(creds.EffectiveKGID), + }, + }); err != nil { + if cleanupErr := vfsObj.RmdirAt(ctx, fs.creds, &pop); cleanupErr != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer directory after MkdirAt metadata update failure: %v", cleanupErr) + } else if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return err + } + if haveUpperWhiteout { + // There may be directories on lower layers (previously hidden by + // the whiteout) that the new directory should not be merged with. + // Mark it opaque to prevent merging. + if err := vfsObj.SetxattrAt(ctx, fs.creds, &pop, &vfs.SetxattrOptions{ + Name: _OVL_XATTR_OPAQUE, + Value: "y", + }); err != nil { + if cleanupErr := vfsObj.RmdirAt(ctx, fs.creds, &pop); cleanupErr != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer directory after MkdirAt set-opaque failure: %v", cleanupErr) + } else { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return err + } + } + return nil + }) +} + +// MknodAt implements vfs.FilesystemImpl.MknodAt. +func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error { + return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error { + // Disallow attempts to create whiteouts. + if opts.Mode&linux.S_IFMT == linux.S_IFCHR && opts.DevMajor == 0 && opts.DevMinor == 0 { + return syserror.EPERM + } + vfsObj := fs.vfsfs.VirtualFilesystem() + pop := vfs.PathOperation{ + Root: parent.upperVD, + Start: parent.upperVD, + Path: fspath.Parse(childName), + } + if haveUpperWhiteout { + if err := vfsObj.UnlinkAt(ctx, fs.creds, &pop); err != nil { + return err + } + } + if err := vfsObj.MknodAt(ctx, fs.creds, &pop, &opts); err != nil { + if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return err + } + creds := rp.Credentials() + if err := vfsObj.SetStatAt(ctx, fs.creds, &pop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: uint32(creds.EffectiveKUID), + GID: uint32(creds.EffectiveKGID), + }, + }); err != nil { + if cleanupErr := vfsObj.UnlinkAt(ctx, fs.creds, &pop); cleanupErr != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer file after MknodAt metadata update failure: %v", cleanupErr) + } else if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return err + } + return nil + }) +} + +// OpenAt implements vfs.FilesystemImpl.OpenAt. +func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.OpenOptions) (*vfs.FileDescription, error) { + mayCreate := opts.Flags&linux.O_CREAT != 0 + mustCreate := opts.Flags&(linux.O_CREAT|linux.O_EXCL) == (linux.O_CREAT | linux.O_EXCL) + + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + + start := rp.Start().Impl().(*dentry) + if rp.Done() { + if mustCreate { + return nil, syserror.EEXIST + } + return start.openLocked(ctx, rp, &opts) + } + +afterTrailingSymlink: + parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds) + if err != nil { + return nil, err + } + // Check for search permission in the parent directory. + if err := parent.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil { + return nil, err + } + // Determine whether or not we need to create a file. + parent.dirMu.Lock() + child, err := fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds) + if err == syserror.ENOENT && mayCreate { + fd, err := fs.createAndOpenLocked(ctx, rp, parent, &opts, &ds) + parent.dirMu.Unlock() + return fd, err + } + if err != nil { + parent.dirMu.Unlock() + return nil, err + } + // Open existing child or follow symlink. + parent.dirMu.Unlock() + if mustCreate { + return nil, syserror.EEXIST + } + if child.isSymlink() && rp.ShouldFollowSymlink() { + target, err := child.readlink(ctx) + if err != nil { + return nil, err + } + if err := rp.HandleSymlink(target); err != nil { + return nil, err + } + start = parent + goto afterTrailingSymlink + } + return child.openLocked(ctx, rp, &opts) +} + +// Preconditions: fs.renameMu must be locked. +func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions) (*vfs.FileDescription, error) { + ats := vfs.AccessTypesForOpenFlags(opts) + if err := d.checkPermissions(rp.Credentials(), ats); err != nil { + return nil, err + } + if ats.MayWrite() { + if err := d.copyUpLocked(ctx); err != nil { + return nil, err + } + } + mnt := rp.Mount() + + // Directory FDs open FDs from each layer when directory entries are read, + // so they don't require opening an FD from d.topLayer() up front. + ftype := atomic.LoadUint32(&d.mode) & linux.S_IFMT + if ftype == linux.S_IFDIR { + // Can't open directories with O_CREAT. + if opts.Flags&linux.O_CREAT != 0 { + return nil, syserror.EISDIR + } + // Can't open directories writably. + if ats&vfs.MayWrite != 0 { + return nil, syserror.EISDIR + } + if opts.Flags&linux.O_DIRECT != 0 { + return nil, syserror.EINVAL + } + fd := &directoryFD{} + fd.LockFD.Init(&d.locks) + if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{ + UseDentryMetadata: true, + }); err != nil { + return nil, err + } + return &fd.vfsfd, nil + } + + layerVD, isUpper := d.topLayerInfo() + layerFD, err := rp.VirtualFilesystem().OpenAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + }, opts) + if err != nil { + return nil, err + } + layerFlags := layerFD.StatusFlags() + fd := &nonDirectoryFD{ + copiedUp: isUpper, + cachedFD: layerFD, + cachedFlags: layerFlags, + } + fd.LockFD.Init(&d.locks) + layerFDOpts := layerFD.Options() + if err := fd.vfsfd.Init(fd, layerFlags, mnt, &d.vfsd, &layerFDOpts); err != nil { + layerFD.DecRef() + return nil, err + } + return &fd.vfsfd, nil +} + +// Preconditions: parent.dirMu must be locked. parent does not already contain +// a child named rp.Component(). +func (fs *filesystem) createAndOpenLocked(ctx context.Context, rp *vfs.ResolvingPath, parent *dentry, opts *vfs.OpenOptions, ds **[]*dentry) (*vfs.FileDescription, error) { + creds := rp.Credentials() + if err := parent.checkPermissions(creds, vfs.MayWrite); err != nil { + return nil, err + } + if parent.vfsd.IsDead() { + return nil, syserror.ENOENT + } + mnt := rp.Mount() + if err := mnt.CheckBeginWrite(); err != nil { + return nil, err + } + defer mnt.EndWrite() + + if err := parent.copyUpLocked(ctx); err != nil { + return nil, err + } + + vfsObj := fs.vfsfs.VirtualFilesystem() + childName := rp.Component() + pop := vfs.PathOperation{ + Root: parent.upperVD, + Start: parent.upperVD, + Path: fspath.Parse(childName), + } + // We don't know if a whiteout exists on the upper layer; speculatively + // unlink it. + // + // TODO(gvisor.dev/issue/1199): Modify OpenAt => stepLocked so that we do + // know whether a whiteout exists. + var haveUpperWhiteout bool + switch err := vfsObj.UnlinkAt(ctx, fs.creds, &pop); err { + case nil: + haveUpperWhiteout = true + case syserror.ENOENT: + haveUpperWhiteout = false + default: + return nil, err + } + // Create the file on the upper layer, and get an FD representing it. + upperFD, err := vfsObj.OpenAt(ctx, fs.creds, &pop, &vfs.OpenOptions{ + Flags: opts.Flags&^vfs.FileCreationFlags | linux.O_CREAT | linux.O_EXCL, + Mode: opts.Mode, + }) + if err != nil { + if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return nil, err + } + // Change the file's owner to the caller. We can't use upperFD.SetStat() + // because it will pick up creds from ctx. + if err := vfsObj.SetStatAt(ctx, fs.creds, &pop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: uint32(creds.EffectiveKUID), + GID: uint32(creds.EffectiveKGID), + }, + }); err != nil { + if cleanupErr := vfsObj.UnlinkAt(ctx, fs.creds, &pop); cleanupErr != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer file after OpenAt(O_CREAT) metadata update failure: %v", cleanupErr) + } else if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return nil, err + } + // Re-lookup to get a dentry representing the new file, which is needed for + // the returned FD. + child, err := fs.getChildLocked(ctx, parent, childName, ds) + if err != nil { + if cleanupErr := vfsObj.UnlinkAt(ctx, fs.creds, &pop); cleanupErr != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer file after OpenAt(O_CREAT) dentry lookup failure: %v", cleanupErr) + } else if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return nil, err + } + // Finally construct the overlay FD. + upperFlags := upperFD.StatusFlags() + fd := &nonDirectoryFD{ + copiedUp: true, + cachedFD: upperFD, + cachedFlags: upperFlags, + } + fd.LockFD.Init(&child.locks) + upperFDOpts := upperFD.Options() + if err := fd.vfsfd.Init(fd, upperFlags, mnt, &child.vfsd, &upperFDOpts); err != nil { + upperFD.DecRef() + // Don't bother with cleanup; the file was created successfully, we + // just can't open it anymore for some reason. + return nil, err + } + return &fd.vfsfd, nil +} + +// ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt. +func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (string, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + d, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return "", err + } + layerVD := d.topLayer() + return fs.vfsfs.VirtualFilesystem().ReadlinkAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + }) +} + +// RenameAt implements vfs.FilesystemImpl.RenameAt. +func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldParentVD vfs.VirtualDentry, oldName string, opts vfs.RenameOptions) error { + if opts.Flags != 0 { + return syserror.EINVAL + } + + var ds *[]*dentry + fs.renameMu.Lock() + defer fs.renameMuUnlockAndCheckDrop(&ds) + newParent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*dentry), &ds) + if err != nil { + return err + } + newName := rp.Component() + if newName == "." || newName == ".." { + return syserror.EBUSY + } + mnt := rp.Mount() + if mnt != oldParentVD.Mount() { + return syserror.EXDEV + } + if err := mnt.CheckBeginWrite(); err != nil { + return err + } + defer mnt.EndWrite() + + // FIXME(gvisor.dev/issue/1199): Actually implement rename. + _ = newParent + return syserror.EXDEV +} + +// RmdirAt implements vfs.FilesystemImpl.RmdirAt. +func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + start := rp.Start().Impl().(*dentry) + parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds) + if err != nil { + return err + } + if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil { + return err + } + if err := rp.Mount().CheckBeginWrite(); err != nil { + return err + } + defer rp.Mount().EndWrite() + name := rp.Component() + if name == "." { + return syserror.EINVAL + } + if name == ".." { + return syserror.ENOTEMPTY + } + vfsObj := rp.VirtualFilesystem() + mntns := vfs.MountNamespaceFromContext(ctx) + defer mntns.DecRef() + parent.dirMu.Lock() + defer parent.dirMu.Unlock() + + // Ensure that parent is copied-up before potentially holding child.copyMu + // below. + if err := parent.copyUpLocked(ctx); err != nil { + return err + } + + // Unlike UnlinkAt, we need a dentry representing the child directory being + // removed in order to verify that it's empty. + child, err := fs.getChildLocked(ctx, parent, name, &ds) + if err != nil { + return err + } + if !child.isDir() { + return syserror.ENOTDIR + } + child.dirMu.Lock() + defer child.dirMu.Unlock() + whiteouts, err := child.collectWhiteoutsForRmdirLocked(ctx) + if err != nil { + return err + } + child.copyMu.RLock() + defer child.copyMu.RUnlock() + if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil { + return err + } + + pop := vfs.PathOperation{ + Root: parent.upperVD, + Start: parent.upperVD, + Path: fspath.Parse(name), + } + if child.upperVD.Ok() { + cleanupRecreateWhiteouts := func() { + if !child.upperVD.Ok() { + return + } + for whiteoutName, whiteoutUpper := range whiteouts { + if !whiteoutUpper { + continue + } + if err := fs.createWhiteout(ctx, vfsObj, &vfs.PathOperation{ + Root: child.upperVD, + Start: child.upperVD, + Path: fspath.Parse(whiteoutName), + }); err != nil && err != syserror.EEXIST { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to recreate deleted whiteout after RmdirAt failure: %v", err) + } + } + } + // Remove existing whiteouts on the upper layer. + for whiteoutName, whiteoutUpper := range whiteouts { + if !whiteoutUpper { + continue + } + if err := vfsObj.UnlinkAt(ctx, fs.creds, &vfs.PathOperation{ + Root: child.upperVD, + Start: child.upperVD, + Path: fspath.Parse(whiteoutName), + }); err != nil { + cleanupRecreateWhiteouts() + vfsObj.AbortDeleteDentry(&child.vfsd) + return err + } + } + // Remove the existing directory on the upper layer. + if err := vfsObj.RmdirAt(ctx, fs.creds, &pop); err != nil { + cleanupRecreateWhiteouts() + vfsObj.AbortDeleteDentry(&child.vfsd) + return err + } + } + if err := fs.createWhiteout(ctx, vfsObj, &pop); err != nil { + // Don't attempt to recover from this: the original directory is + // already gone, so any dentries representing it are invalid, and + // creating a new directory won't undo that. + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to create whiteout during RmdirAt: %v", err) + vfsObj.AbortDeleteDentry(&child.vfsd) + return err + } + + vfsObj.CommitDeleteDentry(&child.vfsd) + delete(parent.children, name) + ds = appendDentry(ds, child) + parent.dirents = nil + return nil +} + +// SetStatAt implements vfs.FilesystemImpl.SetStatAt. +func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + d, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return err + } + + mode := linux.FileMode(atomic.LoadUint32(&d.mode)) + if err := vfs.CheckSetStat(ctx, rp.Credentials(), &opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil { + return err + } + mnt := rp.Mount() + if err := mnt.CheckBeginWrite(); err != nil { + return err + } + defer mnt.EndWrite() + if err := d.copyUpLocked(ctx); err != nil { + return err + } + // Changes to d's attributes are serialized by d.copyMu. + d.copyMu.Lock() + defer d.copyMu.Unlock() + if err := d.fs.vfsfs.VirtualFilesystem().SetStatAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: d.upperVD, + Start: d.upperVD, + }, &opts); err != nil { + return err + } + d.updateAfterSetStatLocked(&opts) + return nil +} + +// StatAt implements vfs.FilesystemImpl.StatAt. +func (fs *filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.StatOptions) (linux.Statx, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + d, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return linux.Statx{}, err + } + + var stat linux.Statx + if layerMask := opts.Mask &^ statInternalMask; layerMask != 0 { + layerVD := d.topLayer() + stat, err = fs.vfsfs.VirtualFilesystem().StatAt(ctx, fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + }, &vfs.StatOptions{ + Mask: layerMask, + Sync: opts.Sync, + }) + if err != nil { + return linux.Statx{}, err + } + } + d.statInternalTo(ctx, &opts, &stat) + return stat, nil +} + +// StatFSAt implements vfs.FilesystemImpl.StatFSAt. +func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linux.Statfs, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + _, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return linux.Statfs{}, err + } + return fs.statFS(ctx) +} + +// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt. +func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error { + return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, haveUpperWhiteout bool) error { + vfsObj := fs.vfsfs.VirtualFilesystem() + pop := vfs.PathOperation{ + Root: parent.upperVD, + Start: parent.upperVD, + Path: fspath.Parse(childName), + } + if haveUpperWhiteout { + if err := vfsObj.UnlinkAt(ctx, fs.creds, &pop); err != nil { + return err + } + } + if err := vfsObj.SymlinkAt(ctx, fs.creds, &pop, target); err != nil { + if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return err + } + creds := rp.Credentials() + if err := vfsObj.SetStatAt(ctx, fs.creds, &pop, &vfs.SetStatOptions{ + Stat: linux.Statx{ + Mask: linux.STATX_UID | linux.STATX_GID, + UID: uint32(creds.EffectiveKUID), + GID: uint32(creds.EffectiveKGID), + }, + }); err != nil { + if cleanupErr := vfsObj.UnlinkAt(ctx, fs.creds, &pop); cleanupErr != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to delete upper layer file after SymlinkAt metadata update failure: %v", cleanupErr) + } else if haveUpperWhiteout { + fs.cleanupRecreateWhiteout(ctx, vfsObj, &pop) + } + return err + } + return nil + }) +} + +// UnlinkAt implements vfs.FilesystemImpl.UnlinkAt. +func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + start := rp.Start().Impl().(*dentry) + parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds) + if err != nil { + return err + } + if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil { + return err + } + if err := rp.Mount().CheckBeginWrite(); err != nil { + return err + } + defer rp.Mount().EndWrite() + name := rp.Component() + if name == "." || name == ".." { + return syserror.EISDIR + } + if rp.MustBeDir() { + return syserror.ENOTDIR + } + vfsObj := rp.VirtualFilesystem() + mntns := vfs.MountNamespaceFromContext(ctx) + defer mntns.DecRef() + parent.dirMu.Lock() + defer parent.dirMu.Unlock() + + // Ensure that parent is copied-up before potentially holding child.copyMu + // below. + if err := parent.copyUpLocked(ctx); err != nil { + return err + } + + child := parent.children[name] + var childLayer lookupLayer + if child != nil { + if child.isDir() { + return syserror.EISDIR + } + if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil { + return err + } + // Hold child.copyMu to prevent it from being copied-up during + // deletion. + child.copyMu.RLock() + defer child.copyMu.RUnlock() + if child.upperVD.Ok() { + childLayer = lookupLayerUpper + } else { + childLayer = lookupLayerLower + } + } else { + // Determine if the file being unlinked actually exists. Holding + // parent.dirMu prevents a dentry from being instantiated for the file, + // which in turn prevents it from being copied-up, so this result is + // stable. + childLayer, err = fs.lookupLayerLocked(ctx, parent, name) + if err != nil { + return err + } + if !childLayer.existsInOverlay() { + return syserror.ENOENT + } + } + + pop := vfs.PathOperation{ + Root: parent.upperVD, + Start: parent.upperVD, + Path: fspath.Parse(name), + } + if childLayer == lookupLayerUpper { + // Remove the existing file on the upper layer. + if err := vfsObj.UnlinkAt(ctx, fs.creds, &pop); err != nil { + if child != nil { + vfsObj.AbortDeleteDentry(&child.vfsd) + } + return err + } + } + if err := fs.createWhiteout(ctx, vfsObj, &pop); err != nil { + ctx.Warningf("Unrecoverable overlayfs inconsistency: failed to create whiteout during UnlinkAt: %v", err) + if child != nil { + vfsObj.AbortDeleteDentry(&child.vfsd) + } + return err + } + + if child != nil { + vfsObj.CommitDeleteDentry(&child.vfsd) + delete(parent.children, name) + ds = appendDentry(ds, child) + } + parent.dirents = nil + return nil +} + +// ListxattrAt implements vfs.FilesystemImpl.ListxattrAt. +func (fs *filesystem) ListxattrAt(ctx context.Context, rp *vfs.ResolvingPath, size uint64) ([]string, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + _, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return nil, err + } + // TODO(gvisor.dev/issue/1199): Linux overlayfs actually allows listxattr, + // but not any other xattr syscalls. For now we just reject all of them. + return nil, syserror.ENOTSUP +} + +// GetxattrAt implements vfs.FilesystemImpl.GetxattrAt. +func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetxattrOptions) (string, error) { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + _, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return "", err + } + return "", syserror.ENOTSUP +} + +// SetxattrAt implements vfs.FilesystemImpl.SetxattrAt. +func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + _, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return err + } + return syserror.ENOTSUP +} + +// RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt. +func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error { + var ds *[]*dentry + fs.renameMu.RLock() + defer fs.renameMuRUnlockAndCheckDrop(&ds) + _, err := fs.resolveLocked(ctx, rp, &ds) + if err != nil { + return err + } + return syserror.ENOTSUP +} + +// PrependPath implements vfs.FilesystemImpl.PrependPath. +func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error { + fs.renameMu.RLock() + defer fs.renameMu.RUnlock() + return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b) +} diff --git a/pkg/sentry/fsimpl/overlay/non_directory.go b/pkg/sentry/fsimpl/overlay/non_directory.go new file mode 100644 index 000000000..c0749e711 --- /dev/null +++ b/pkg/sentry/fsimpl/overlay/non_directory.go @@ -0,0 +1,266 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package overlay + +import ( + "sync/atomic" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/memmap" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/usermem" +) + +func (d *dentry) isSymlink() bool { + return atomic.LoadUint32(&d.mode)&linux.S_IFMT == linux.S_IFLNK +} + +func (d *dentry) readlink(ctx context.Context) (string, error) { + layerVD := d.topLayer() + return d.fs.vfsfs.VirtualFilesystem().ReadlinkAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: layerVD, + Start: layerVD, + }) +} + +type nonDirectoryFD struct { + fileDescription + + // If copiedUp is false, cachedFD represents + // fileDescription.dentry().lowerVDs[0]; otherwise, cachedFD represents + // fileDescription.dentry().upperVD. cachedFlags is the last known value of + // cachedFD.StatusFlags(). copiedUp, cachedFD, and cachedFlags are + // protected by mu. + mu sync.Mutex + copiedUp bool + cachedFD *vfs.FileDescription + cachedFlags uint32 +} + +func (fd *nonDirectoryFD) getCurrentFD(ctx context.Context) (*vfs.FileDescription, error) { + fd.mu.Lock() + defer fd.mu.Unlock() + wrappedFD, err := fd.currentFDLocked(ctx) + if err != nil { + return nil, err + } + wrappedFD.IncRef() + return wrappedFD, nil +} + +func (fd *nonDirectoryFD) currentFDLocked(ctx context.Context) (*vfs.FileDescription, error) { + d := fd.dentry() + statusFlags := fd.vfsfd.StatusFlags() + if !fd.copiedUp && d.isCopiedUp() { + // Switch to the copied-up file. + upperVD := d.topLayer() + upperFD, err := fd.filesystem().vfsfs.VirtualFilesystem().OpenAt(ctx, d.fs.creds, &vfs.PathOperation{ + Root: upperVD, + Start: upperVD, + }, &vfs.OpenOptions{ + Flags: statusFlags, + }) + if err != nil { + return nil, err + } + oldOff, oldOffErr := fd.cachedFD.Seek(ctx, 0, linux.SEEK_CUR) + if oldOffErr == nil { + if _, err := upperFD.Seek(ctx, oldOff, linux.SEEK_SET); err != nil { + upperFD.DecRef() + return nil, err + } + } + fd.cachedFD.DecRef() + fd.copiedUp = true + fd.cachedFD = upperFD + fd.cachedFlags = statusFlags + } else if fd.cachedFlags != statusFlags { + if err := fd.cachedFD.SetStatusFlags(ctx, d.fs.creds, statusFlags); err != nil { + return nil, err + } + fd.cachedFlags = statusFlags + } + return fd.cachedFD, nil +} + +// Release implements vfs.FileDescriptionImpl.Release. +func (fd *nonDirectoryFD) Release() { + fd.cachedFD.DecRef() + fd.cachedFD = nil +} + +// OnClose implements vfs.FileDescriptionImpl.OnClose. +func (fd *nonDirectoryFD) OnClose(ctx context.Context) error { + // Linux doesn't define ovl_file_operations.flush at all (i.e. its + // equivalent to OnClose is a no-op). We pass through to + // fd.cachedFD.OnClose() without upgrading if fd.dentry() has been + // copied-up, since OnClose is mostly used to define post-close writeback, + // and if fd.cachedFD hasn't been updated then it can't have been used to + // mutate fd.dentry() anyway. + fd.mu.Lock() + if statusFlags := fd.vfsfd.StatusFlags(); fd.cachedFlags != statusFlags { + if err := fd.cachedFD.SetStatusFlags(ctx, fd.filesystem().creds, statusFlags); err != nil { + fd.mu.Unlock() + return err + } + fd.cachedFlags = statusFlags + } + wrappedFD := fd.cachedFD + defer wrappedFD.IncRef() + fd.mu.Unlock() + return wrappedFD.OnClose(ctx) +} + +// Stat implements vfs.FileDescriptionImpl.Stat. +func (fd *nonDirectoryFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { + var stat linux.Statx + if layerMask := opts.Mask &^ statInternalMask; layerMask != 0 { + wrappedFD, err := fd.getCurrentFD(ctx) + if err != nil { + return linux.Statx{}, err + } + stat, err = wrappedFD.Stat(ctx, vfs.StatOptions{ + Mask: layerMask, + Sync: opts.Sync, + }) + wrappedFD.DecRef() + if err != nil { + return linux.Statx{}, err + } + } + fd.dentry().statInternalTo(ctx, &opts, &stat) + return stat, nil +} + +// SetStat implements vfs.FileDescriptionImpl.SetStat. +func (fd *nonDirectoryFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error { + d := fd.dentry() + mode := linux.FileMode(atomic.LoadUint32(&d.mode)) + if err := vfs.CheckSetStat(ctx, auth.CredentialsFromContext(ctx), &opts, mode, auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))); err != nil { + return err + } + mnt := fd.vfsfd.Mount() + if err := mnt.CheckBeginWrite(); err != nil { + return err + } + defer mnt.EndWrite() + if err := d.copyUpLocked(ctx); err != nil { + return err + } + // Changes to d's attributes are serialized by d.copyMu. + d.copyMu.Lock() + defer d.copyMu.Unlock() + wrappedFD, err := fd.currentFDLocked(ctx) + if err != nil { + return err + } + if err := wrappedFD.SetStat(ctx, opts); err != nil { + return err + } + d.updateAfterSetStatLocked(&opts) + return nil +} + +// StatFS implements vfs.FileDescriptionImpl.StatFS. +func (fd *nonDirectoryFD) StatFS(ctx context.Context) (linux.Statfs, error) { + return fd.filesystem().statFS(ctx) +} + +// PRead implements vfs.FileDescriptionImpl.PRead. +func (fd *nonDirectoryFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { + wrappedFD, err := fd.getCurrentFD(ctx) + if err != nil { + return 0, err + } + defer wrappedFD.DecRef() + return wrappedFD.PRead(ctx, dst, offset, opts) +} + +// Read implements vfs.FileDescriptionImpl.Read. +func (fd *nonDirectoryFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) { + // Hold fd.mu during the read to serialize the file offset. + fd.mu.Lock() + defer fd.mu.Unlock() + wrappedFD, err := fd.currentFDLocked(ctx) + if err != nil { + return 0, err + } + return wrappedFD.Read(ctx, dst, opts) +} + +// PWrite implements vfs.FileDescriptionImpl.PWrite. +func (fd *nonDirectoryFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + wrappedFD, err := fd.getCurrentFD(ctx) + if err != nil { + return 0, err + } + defer wrappedFD.DecRef() + return wrappedFD.PWrite(ctx, src, offset, opts) +} + +// Write implements vfs.FileDescriptionImpl.Write. +func (fd *nonDirectoryFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { + // Hold fd.mu during the write to serialize the file offset. + fd.mu.Lock() + defer fd.mu.Unlock() + wrappedFD, err := fd.currentFDLocked(ctx) + if err != nil { + return 0, err + } + return wrappedFD.Write(ctx, src, opts) +} + +// Seek implements vfs.FileDescriptionImpl.Seek. +func (fd *nonDirectoryFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { + // Hold fd.mu during the seek to serialize the file offset. + fd.mu.Lock() + defer fd.mu.Unlock() + wrappedFD, err := fd.currentFDLocked(ctx) + if err != nil { + return 0, err + } + return wrappedFD.Seek(ctx, offset, whence) +} + +// Sync implements vfs.FileDescriptionImpl.Sync. +func (fd *nonDirectoryFD) Sync(ctx context.Context) error { + fd.mu.Lock() + if !fd.dentry().isCopiedUp() { + fd.mu.Unlock() + return nil + } + wrappedFD, err := fd.currentFDLocked(ctx) + if err != nil { + fd.mu.Unlock() + return err + } + wrappedFD.IncRef() + defer wrappedFD.DecRef() + fd.mu.Unlock() + return wrappedFD.Sync(ctx) +} + +// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap. +func (fd *nonDirectoryFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error { + wrappedFD, err := fd.getCurrentFD(ctx) + if err != nil { + return err + } + defer wrappedFD.DecRef() + return wrappedFD.ConfigureMMap(ctx, opts) +} diff --git a/pkg/sentry/fsimpl/overlay/overlay.go b/pkg/sentry/fsimpl/overlay/overlay.go new file mode 100644 index 000000000..e720d4825 --- /dev/null +++ b/pkg/sentry/fsimpl/overlay/overlay.go @@ -0,0 +1,627 @@ +// Copyright 2020 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +// Package overlay provides an overlay filesystem implementation, which +// synthesizes a filesystem by composing one or more immutable filesystems +// ("lower layers") with an optional mutable filesystem ("upper layer"). +// +// Lock order: +// +// directoryFD.mu / nonDirectoryFD.mu +// filesystem.renameMu +// dentry.dirMu +// dentry.copyMu +// +// Locking dentry.dirMu in multiple dentries requires that parent dentries are +// locked before child dentries, and that filesystem.renameMu is locked to +// stabilize this relationship. +package overlay + +import ( + "strings" + "sync/atomic" + + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" + "gvisor.dev/gvisor/pkg/fspath" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" + "gvisor.dev/gvisor/pkg/sentry/vfs" + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/syserror" +) + +// Name is the default filesystem name. +const Name = "overlay" + +// FilesystemType implements vfs.FilesystemType. +type FilesystemType struct{} + +// Name implements vfs.FilesystemType.Name. +func (FilesystemType) Name() string { + return Name +} + +// FilesystemOptions may be passed as vfs.GetFilesystemOptions.InternalData to +// FilesystemType.GetFilesystem. +type FilesystemOptions struct { + // Callers passing FilesystemOptions to + // overlay.FilesystemType.GetFilesystem() are responsible for ensuring that + // the vfs.Mounts comprising the layers of the overlay filesystem do not + // contain submounts. + + // If UpperRoot.Ok(), it is the root of the writable upper layer of the + // overlay. + UpperRoot vfs.VirtualDentry + + // LowerRoots contains the roots of the immutable lower layers of the + // overlay. LowerRoots is immutable. + LowerRoots []vfs.VirtualDentry +} + +// filesystem implements vfs.FilesystemImpl. +type filesystem struct { + vfsfs vfs.Filesystem + + // Immutable options. + opts FilesystemOptions + + // creds is a copy of the filesystem's creator's credentials, which are + // used for accesses to the filesystem's layers. creds is immutable. + creds *auth.Credentials + + // dirDevMinor is the device minor number used for directories. dirDevMinor + // is immutable. + dirDevMinor uint32 + + // lowerDevMinors maps lower layer filesystems to device minor numbers + // assigned to non-directory files originating from that filesystem. + // lowerDevMinors is immutable. + lowerDevMinors map[*vfs.Filesystem]uint32 + + // renameMu synchronizes renaming with non-renaming operations in order to + // ensure consistent lock ordering between dentry.dirMu in different + // dentries. + renameMu sync.RWMutex + + // lastDirIno is the last inode number assigned to a directory. lastDirIno + // is accessed using atomic memory operations. + lastDirIno uint64 +} + +// GetFilesystem implements vfs.FilesystemType.GetFilesystem. +func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) { + mopts := vfs.GenericParseMountOptions(opts.Data) + fsoptsRaw := opts.InternalData + fsopts, haveFSOpts := fsoptsRaw.(FilesystemOptions) + if fsoptsRaw != nil && !haveFSOpts { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: GetFilesystemOptions.InternalData has type %T, wanted overlay.FilesystemOptions or nil", fsoptsRaw) + return nil, nil, syserror.EINVAL + } + if haveFSOpts { + if len(fsopts.LowerRoots) == 0 { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: LowerRoots must be non-empty") + return nil, nil, syserror.EINVAL + } + if len(fsopts.LowerRoots) < 2 && !fsopts.UpperRoot.Ok() { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: at least two LowerRoots are required when UpperRoot is unspecified") + return nil, nil, syserror.EINVAL + } + // We don't enforce a maximum number of lower layers when not + // configured by applications; the sandbox owner can have an overlay + // filesystem with any number of lower layers. + } else { + vfsroot := vfs.RootFromContext(ctx) + defer vfsroot.DecRef() + upperPathname, ok := mopts["upperdir"] + if ok { + delete(mopts, "upperdir") + // Linux overlayfs also requires a workdir when upperdir is + // specified; we don't, so silently ignore this option. + delete(mopts, "workdir") + upperPath := fspath.Parse(upperPathname) + if !upperPath.Absolute { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: upperdir %q must be absolute", upperPathname) + return nil, nil, syserror.EINVAL + } + upperRoot, err := vfsObj.GetDentryAt(ctx, creds, &vfs.PathOperation{ + Root: vfsroot, + Start: vfsroot, + Path: upperPath, + FollowFinalSymlink: true, + }, &vfs.GetDentryOptions{ + CheckSearchable: true, + }) + if err != nil { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: failed to resolve upperdir %q: %v", upperPathname, err) + return nil, nil, err + } + defer upperRoot.DecRef() + privateUpperRoot, err := clonePrivateMount(vfsObj, upperRoot, false /* forceReadOnly */) + if err != nil { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: failed to make private bind mount of upperdir %q: %v", upperPathname, err) + return nil, nil, err + } + defer privateUpperRoot.DecRef() + fsopts.UpperRoot = privateUpperRoot + } + lowerPathnamesStr, ok := mopts["lowerdir"] + if !ok { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: missing required option lowerdir") + return nil, nil, syserror.EINVAL + } + delete(mopts, "lowerdir") + lowerPathnames := strings.Split(lowerPathnamesStr, ":") + const maxLowerLayers = 500 // Linux: fs/overlay/super.c:OVL_MAX_STACK + if len(lowerPathnames) < 2 && !fsopts.UpperRoot.Ok() { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: at least two lowerdirs are required when upperdir is unspecified") + return nil, nil, syserror.EINVAL + } + if len(lowerPathnames) > maxLowerLayers { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: %d lowerdirs specified, maximum %d", len(lowerPathnames), maxLowerLayers) + return nil, nil, syserror.EINVAL + } + for _, lowerPathname := range lowerPathnames { + lowerPath := fspath.Parse(lowerPathname) + if !lowerPath.Absolute { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: lowerdir %q must be absolute", lowerPathname) + return nil, nil, syserror.EINVAL + } + lowerRoot, err := vfsObj.GetDentryAt(ctx, creds, &vfs.PathOperation{ + Root: vfsroot, + Start: vfsroot, + Path: lowerPath, + FollowFinalSymlink: true, + }, &vfs.GetDentryOptions{ + CheckSearchable: true, + }) + if err != nil { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: failed to resolve lowerdir %q: %v", lowerPathname, err) + return nil, nil, err + } + defer lowerRoot.DecRef() + privateLowerRoot, err := clonePrivateMount(vfsObj, lowerRoot, true /* forceReadOnly */) + if err != nil { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: failed to make private bind mount of lowerdir %q: %v", lowerPathname, err) + return nil, nil, err + } + defer privateLowerRoot.DecRef() + fsopts.LowerRoots = append(fsopts.LowerRoots, privateLowerRoot) + } + } + if len(mopts) != 0 { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: unused options: %v", mopts) + return nil, nil, syserror.EINVAL + } + + // Allocate device numbers. + dirDevMinor, err := vfsObj.GetAnonBlockDevMinor() + if err != nil { + return nil, nil, err + } + lowerDevMinors := make(map[*vfs.Filesystem]uint32) + for _, lowerRoot := range fsopts.LowerRoots { + lowerFS := lowerRoot.Mount().Filesystem() + if _, ok := lowerDevMinors[lowerFS]; !ok { + devMinor, err := vfsObj.GetAnonBlockDevMinor() + if err != nil { + vfsObj.PutAnonBlockDevMinor(dirDevMinor) + for _, lowerDevMinor := range lowerDevMinors { + vfsObj.PutAnonBlockDevMinor(lowerDevMinor) + } + return nil, nil, err + } + lowerDevMinors[lowerFS] = devMinor + } + } + + // Take extra references held by the filesystem. + if fsopts.UpperRoot.Ok() { + fsopts.UpperRoot.IncRef() + } + for _, lowerRoot := range fsopts.LowerRoots { + lowerRoot.IncRef() + } + + fs := &filesystem{ + opts: fsopts, + creds: creds.Fork(), + dirDevMinor: dirDevMinor, + lowerDevMinors: lowerDevMinors, + } + fs.vfsfs.Init(vfsObj, &fstype, fs) + + // Construct the root dentry. + root := fs.newDentry() + root.refs = 1 + if fs.opts.UpperRoot.Ok() { + fs.opts.UpperRoot.IncRef() + root.copiedUp = 1 + root.upperVD = fs.opts.UpperRoot + } + for _, lowerRoot := range fs.opts.LowerRoots { + lowerRoot.IncRef() + root.lowerVDs = append(root.lowerVDs, lowerRoot) + } + rootTopVD := root.topLayer() + // Get metadata from the topmost layer. See fs.lookupLocked(). + const rootStatMask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_INO + rootStat, err := vfsObj.StatAt(ctx, creds, &vfs.PathOperation{ + Root: rootTopVD, + Start: rootTopVD, + }, &vfs.StatOptions{ + Mask: rootStatMask, + }) + if err != nil { + root.destroyLocked() + fs.vfsfs.DecRef() + return nil, nil, err + } + if rootStat.Mask&rootStatMask != rootStatMask { + root.destroyLocked() + fs.vfsfs.DecRef() + return nil, nil, syserror.EREMOTE + } + if isWhiteout(&rootStat) { + ctx.Warningf("overlay.FilesystemType.GetFilesystem: filesystem root is a whiteout") + root.destroyLocked() + fs.vfsfs.DecRef() + return nil, nil, syserror.EINVAL + } + root.mode = uint32(rootStat.Mode) + root.uid = rootStat.UID + root.gid = rootStat.GID + if rootStat.Mode&linux.S_IFMT == linux.S_IFDIR { + root.devMajor = linux.UNNAMED_MAJOR + root.devMinor = fs.dirDevMinor + root.ino = fs.newDirIno() + } else if !root.upperVD.Ok() { + root.devMajor = linux.UNNAMED_MAJOR + root.devMinor = fs.lowerDevMinors[root.lowerVDs[0].Mount().Filesystem()] + root.ino = rootStat.Ino + } else { + root.devMajor = rootStat.DevMajor + root.devMinor = rootStat.DevMinor + root.ino = rootStat.Ino + } + + return &fs.vfsfs, &root.vfsd, nil +} + +// clonePrivateMount creates a non-recursive bind mount rooted at vd, not +// associated with any MountNamespace, and returns the root of the new mount. +// (This is required to ensure that each layer of an overlay comprises only a +// single mount, and therefore can't cross into e.g. the overlay filesystem +// itself, risking lock recursion.) A reference is held on the returned +// VirtualDentry. +func clonePrivateMount(vfsObj *vfs.VirtualFilesystem, vd vfs.VirtualDentry, forceReadOnly bool) (vfs.VirtualDentry, error) { + oldmnt := vd.Mount() + opts := oldmnt.Options() + if forceReadOnly { + opts.ReadOnly = true + } + newmnt, err := vfsObj.NewDisconnectedMount(oldmnt.Filesystem(), vd.Dentry(), &opts) + if err != nil { + return vfs.VirtualDentry{}, err + } + return vfs.MakeVirtualDentry(newmnt, vd.Dentry()), nil +} + +// Release implements vfs.FilesystemImpl.Release. +func (fs *filesystem) Release() { + vfsObj := fs.vfsfs.VirtualFilesystem() + vfsObj.PutAnonBlockDevMinor(fs.dirDevMinor) + for _, lowerDevMinor := range fs.lowerDevMinors { + vfsObj.PutAnonBlockDevMinor(lowerDevMinor) + } + if fs.opts.UpperRoot.Ok() { + fs.opts.UpperRoot.DecRef() + } + for _, lowerRoot := range fs.opts.LowerRoots { + lowerRoot.DecRef() + } +} + +func (fs *filesystem) statFS(ctx context.Context) (linux.Statfs, error) { + // Always statfs the root of the topmost layer. Compare Linux's + // fs/overlayfs/super.c:ovl_statfs(). + var rootVD vfs.VirtualDentry + if fs.opts.UpperRoot.Ok() { + rootVD = fs.opts.UpperRoot + } else { + rootVD = fs.opts.LowerRoots[0] + } + fsstat, err := fs.vfsfs.VirtualFilesystem().StatFSAt(ctx, fs.creds, &vfs.PathOperation{ + Root: rootVD, + Start: rootVD, + }) + if err != nil { + return linux.Statfs{}, err + } + fsstat.Type = linux.OVERLAYFS_SUPER_MAGIC + return fsstat, nil +} + +func (fs *filesystem) newDirIno() uint64 { + return atomic.AddUint64(&fs.lastDirIno, 1) +} + +// dentry implements vfs.DentryImpl. +type dentry struct { + vfsd vfs.Dentry + + refs int64 + + // fs is the owning filesystem. fs is immutable. + fs *filesystem + + // mode, uid, and gid are the file mode, owner, and group of the file in + // the topmost layer (and therefore the overlay file as well), and are used + // for permission checks on this dentry. These fields are protected by + // copyMu and accessed using atomic memory operations. + mode uint32 + uid uint32 + gid uint32 + + // copiedUp is 1 if this dentry has been copied-up (i.e. upperVD.Ok()) and + // 0 otherwise. copiedUp is accessed using atomic memory operations. + copiedUp uint32 + + // parent is the dentry corresponding to this dentry's parent directory. + // name is this dentry's name in parent. If this dentry is a filesystem + // root, parent is nil and name is the empty string. parent and name are + // protected by fs.renameMu. + parent *dentry + name string + + // If this dentry represents a directory, children maps the names of + // children for which dentries have been instantiated to those dentries, + // and dirents (if not nil) is a cache of dirents as returned by + // directoryFDs representing this directory. children is protected by + // dirMu. + dirMu sync.Mutex + children map[string]*dentry + dirents []vfs.Dirent + + // upperVD and lowerVDs are the files from the overlay filesystem's layers + // that comprise the file on the overlay filesystem. + // + // If !upperVD.Ok(), it can transition to a valid vfs.VirtualDentry (i.e. + // be copied up) with copyMu locked for writing; otherwise, it is + // immutable. lowerVDs is always immutable. + copyMu sync.RWMutex + upperVD vfs.VirtualDentry + lowerVDs []vfs.VirtualDentry + + // inlineLowerVDs backs lowerVDs in the common case where len(lowerVDs) <= + // len(inlineLowerVDs). + inlineLowerVDs [1]vfs.VirtualDentry + + // devMajor, devMinor, and ino are the device major/minor and inode numbers + // used by this dentry. These fields are protected by copyMu and accessed + // using atomic memory operations. + devMajor uint32 + devMinor uint32 + ino uint64 + + locks vfs.FileLocks +} + +// newDentry creates a new dentry. The dentry initially has no references; it +// is the caller's responsibility to set the dentry's reference count and/or +// call dentry.destroy() as appropriate. The dentry is initially invalid in +// that it contains no layers; the caller is responsible for setting them. +func (fs *filesystem) newDentry() *dentry { + d := &dentry{ + fs: fs, + } + d.lowerVDs = d.inlineLowerVDs[:0] + d.vfsd.Init(d) + return d +} + +// IncRef implements vfs.DentryImpl.IncRef. +func (d *dentry) IncRef() { + // d.refs may be 0 if d.fs.renameMu is locked, which serializes against + // d.checkDropLocked(). + atomic.AddInt64(&d.refs, 1) +} + +// TryIncRef implements vfs.DentryImpl.TryIncRef. +func (d *dentry) TryIncRef() bool { + for { + refs := atomic.LoadInt64(&d.refs) + if refs <= 0 { + return false + } + if atomic.CompareAndSwapInt64(&d.refs, refs, refs+1) { + return true + } + } +} + +// DecRef implements vfs.DentryImpl.DecRef. +func (d *dentry) DecRef() { + if refs := atomic.AddInt64(&d.refs, -1); refs == 0 { + d.fs.renameMu.Lock() + d.checkDropLocked() + d.fs.renameMu.Unlock() + } else if refs < 0 { + panic("overlay.dentry.DecRef() called without holding a reference") + } +} + +// checkDropLocked should be called after d's reference count becomes 0 or it +// becomes deleted. +// +// Preconditions: d.fs.renameMu must be locked for writing. +func (d *dentry) checkDropLocked() { + // Dentries with a positive reference count must be retained. (The only way + // to obtain a reference on a dentry with zero references is via path + // resolution, which requires renameMu, so if d.refs is zero then it will + // remain zero while we hold renameMu for writing.) Dentries with a + // negative reference count have already been destroyed. + if atomic.LoadInt64(&d.refs) != 0 { + return + } + // Refs is still zero; destroy it. + d.destroyLocked() + return +} + +// destroyLocked destroys the dentry. +// +// Preconditions: d.fs.renameMu must be locked for writing. d.refs == 0. +func (d *dentry) destroyLocked() { + switch atomic.LoadInt64(&d.refs) { + case 0: + // Mark the dentry destroyed. + atomic.StoreInt64(&d.refs, -1) + case -1: + panic("overlay.dentry.destroyLocked() called on already destroyed dentry") + default: + panic("overlay.dentry.destroyLocked() called with references on the dentry") + } + + if d.upperVD.Ok() { + d.upperVD.DecRef() + } + for _, lowerVD := range d.lowerVDs { + lowerVD.DecRef() + } + + if d.parent != nil { + d.parent.dirMu.Lock() + if !d.vfsd.IsDead() { + delete(d.parent.children, d.name) + } + d.parent.dirMu.Unlock() + // Drop the reference held by d on its parent without recursively + // locking d.fs.renameMu. + if refs := atomic.AddInt64(&d.parent.refs, -1); refs == 0 { + d.parent.checkDropLocked() + } else if refs < 0 { + panic("overlay.dentry.DecRef() called without holding a reference") + } + } +} + +// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. +func (d *dentry) InotifyWithParent(events uint32, cookie uint32, et vfs.EventType) { + // TODO(gvisor.dev/issue/1479): Implement inotify. +} + +// Watches implements vfs.DentryImpl.Watches. +func (d *dentry) Watches() *vfs.Watches { + // TODO(gvisor.dev/issue/1479): Implement inotify. + return nil +} + +// OnZeroWatches implements vfs.DentryImpl.OnZeroWatches. +// +// TODO(gvisor.dev/issue/1479): Implement inotify. +func (d *dentry) OnZeroWatches() {} + +// iterLayers invokes yield on each layer comprising d, from top to bottom. If +// any call to yield returns false, iterLayer stops iteration. +func (d *dentry) iterLayers(yield func(vd vfs.VirtualDentry, isUpper bool) bool) { + if d.isCopiedUp() { + if !yield(d.upperVD, true) { + return + } + } + for _, lowerVD := range d.lowerVDs { + if !yield(lowerVD, false) { + return + } + } +} + +func (d *dentry) topLayerInfo() (vd vfs.VirtualDentry, isUpper bool) { + if d.isCopiedUp() { + return d.upperVD, true + } + return d.lowerVDs[0], false +} + +func (d *dentry) topLayer() vfs.VirtualDentry { + vd, _ := d.topLayerInfo() + return vd +} + +func (d *dentry) checkPermissions(creds *auth.Credentials, ats vfs.AccessTypes) error { + return vfs.GenericCheckPermissions(creds, ats, linux.FileMode(atomic.LoadUint32(&d.mode)), auth.KUID(atomic.LoadUint32(&d.uid)), auth.KGID(atomic.LoadUint32(&d.gid))) +} + +// statInternalMask is the set of stat fields that is set by +// dentry.statInternalTo(). +const statInternalMask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_UID | linux.STATX_GID | linux.STATX_INO + +// statInternalTo writes fields to stat that are stored in d, and therefore do +// not requiring invoking StatAt on the overlay's layers. +func (d *dentry) statInternalTo(ctx context.Context, opts *vfs.StatOptions, stat *linux.Statx) { + stat.Mask |= statInternalMask + if d.isDir() { + // Linux sets nlink to 1 for merged directories + // (fs/overlayfs/inode.c:ovl_getattr()); we set it to 2 because this is + // correct more often ("." and the directory's entry in its parent), + // and some of our tests expect this. + stat.Nlink = 2 + } + stat.UID = atomic.LoadUint32(&d.uid) + stat.GID = atomic.LoadUint32(&d.gid) + stat.Mode = uint16(atomic.LoadUint32(&d.mode)) + stat.Ino = atomic.LoadUint64(&d.ino) + stat.DevMajor = atomic.LoadUint32(&d.devMajor) + stat.DevMinor = atomic.LoadUint32(&d.devMinor) +} + +// Preconditions: d.copyMu must be locked for writing. +func (d *dentry) updateAfterSetStatLocked(opts *vfs.SetStatOptions) { + if opts.Stat.Mask&linux.STATX_MODE != 0 { + atomic.StoreUint32(&d.mode, (d.mode&linux.S_IFMT)|uint32(opts.Stat.Mode&^linux.S_IFMT)) + } + if opts.Stat.Mask&linux.STATX_UID != 0 { + atomic.StoreUint32(&d.uid, opts.Stat.UID) + } + if opts.Stat.Mask&linux.STATX_GID != 0 { + atomic.StoreUint32(&d.gid, opts.Stat.GID) + } +} + +// fileDescription is embedded by overlay implementations of +// vfs.FileDescriptionImpl. +type fileDescription struct { + vfsfd vfs.FileDescription + vfs.FileDescriptionDefaultImpl + vfs.LockFD +} + +func (fd *fileDescription) filesystem() *filesystem { + return fd.vfsfd.Mount().Filesystem().Impl().(*filesystem) +} + +func (fd *fileDescription) dentry() *dentry { + return fd.vfsfd.Dentry().Impl().(*dentry) +} + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *fileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *fileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) +} diff --git a/pkg/sentry/fsimpl/pipefs/pipefs.go b/pkg/sentry/fsimpl/pipefs/pipefs.go index cab771211..811f80a5f 100644 --- a/pkg/sentry/fsimpl/pipefs/pipefs.go +++ b/pkg/sentry/fsimpl/pipefs/pipefs.go @@ -81,7 +81,8 @@ type inode struct { kernfs.InodeNotSymlink kernfs.InodeNoopRefCount - pipe *pipe.VFSPipe + locks vfs.FileLocks + pipe *pipe.VFSPipe ino uint64 uid auth.KUID @@ -114,7 +115,7 @@ func (i *inode) Mode() linux.FileMode { } // Stat implements kernfs.Inode.Stat. -func (i *inode) Stat(vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { +func (i *inode) Stat(_ context.Context, vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { ts := linux.NsecToStatxTimestamp(i.ctime.Nanoseconds()) return linux.Statx{ Mask: linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_NLINK | linux.STATX_UID | linux.STATX_GID | linux.STATX_ATIME | linux.STATX_MTIME | linux.STATX_CTIME | linux.STATX_INO | linux.STATX_SIZE | linux.STATX_BLOCKS, @@ -147,7 +148,7 @@ func (i *inode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds *auth. // Open implements kernfs.Inode.Open. func (i *inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - return i.pipe.Open(ctx, rp.Mount(), vfsd, opts.Flags) + return i.pipe.Open(ctx, rp.Mount(), vfsd, opts.Flags, &i.locks) } // NewConnectedPipeFDs returns a pair of FileDescriptions representing the read diff --git a/pkg/sentry/fsimpl/proc/BUILD b/pkg/sentry/fsimpl/proc/BUILD index 17c1342b5..6014138ff 100644 --- a/pkg/sentry/fsimpl/proc/BUILD +++ b/pkg/sentry/fsimpl/proc/BUILD @@ -22,6 +22,7 @@ go_library( "//pkg/log", "//pkg/refs", "//pkg/safemem", + "//pkg/sentry/fs/lock", "//pkg/sentry/fsbridge", "//pkg/sentry/fsimpl/kernfs", "//pkg/sentry/inet", diff --git a/pkg/sentry/fsimpl/proc/subtasks.go b/pkg/sentry/fsimpl/proc/subtasks.go index 36a911db4..79c2725f3 100644 --- a/pkg/sentry/fsimpl/proc/subtasks.go +++ b/pkg/sentry/fsimpl/proc/subtasks.go @@ -37,6 +37,8 @@ type subtasksInode struct { kernfs.OrderedChildren kernfs.AlwaysValid + locks vfs.FileLocks + fs *filesystem task *kernel.Task pidns *kernel.PIDNamespace @@ -126,7 +128,7 @@ func (fd *subtasksFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallbac return fd.GenericDirectoryFD.IterDirents(ctx, cb) } -// Seek implements vfs.FileDecriptionImpl.Seek. +// Seek implements vfs.FileDescriptionImpl.Seek. func (fd *subtasksFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) { if fd.task.ExitState() >= kernel.TaskExitZombie { return 0, syserror.ENOENT @@ -153,7 +155,7 @@ func (fd *subtasksFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) erro // Open implements kernfs.Inode. func (i *subtasksInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { fd := &subtasksFD{task: i.task} - if err := fd.Init(&i.OrderedChildren, &opts); err != nil { + if err := fd.Init(&i.OrderedChildren, &i.locks, &opts); err != nil { return nil, err } if err := fd.VFSFileDescription().Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil { @@ -163,8 +165,8 @@ func (i *subtasksInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *v } // Stat implements kernfs.Inode. -func (i *subtasksInode) Stat(vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { - stat, err := i.InodeAttrs.Stat(vsfs, opts) +func (i *subtasksInode) Stat(ctx context.Context, vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { + stat, err := i.InodeAttrs.Stat(ctx, vsfs, opts) if err != nil { return linux.Statx{}, err } diff --git a/pkg/sentry/fsimpl/proc/task.go b/pkg/sentry/fsimpl/proc/task.go index 482055db1..a5c7aa470 100644 --- a/pkg/sentry/fsimpl/proc/task.go +++ b/pkg/sentry/fsimpl/proc/task.go @@ -38,6 +38,8 @@ type taskInode struct { kernfs.InodeAttrs kernfs.OrderedChildren + locks vfs.FileLocks + task *kernel.Task } @@ -103,7 +105,7 @@ func (i *taskInode) Valid(ctx context.Context) bool { // Open implements kernfs.Inode. func (i *taskInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) if err != nil { return nil, err } @@ -154,8 +156,8 @@ func (fs *filesystem) newTaskOwnedDir(task *kernel.Task, ino uint64, perm linux. } // Stat implements kernfs.Inode. -func (i *taskOwnedInode) Stat(fs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { - stat, err := i.Inode.Stat(fs, opts) +func (i *taskOwnedInode) Stat(ctx context.Context, fs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { + stat, err := i.Inode.Stat(ctx, fs, opts) if err != nil { return linux.Statx{}, err } diff --git a/pkg/sentry/fsimpl/proc/task_fds.go b/pkg/sentry/fsimpl/proc/task_fds.go index 44ccc9e4a..fea29e5f0 100644 --- a/pkg/sentry/fsimpl/proc/task_fds.go +++ b/pkg/sentry/fsimpl/proc/task_fds.go @@ -53,6 +53,8 @@ func taskFDExists(t *kernel.Task, fd int32) bool { } type fdDir struct { + locks vfs.FileLocks + fs *filesystem task *kernel.Task @@ -62,7 +64,7 @@ type fdDir struct { } // IterDirents implements kernfs.inodeDynamicLookup. -func (i *fdDir) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, absOffset, relOffset int64) (int64, error) { +func (i *fdDir) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, offset, relOffset int64) (int64, error) { var fds []int32 i.task.WithMuLocked(func(t *kernel.Task) { if fdTable := t.FDTable(); fdTable != nil { @@ -70,7 +72,6 @@ func (i *fdDir) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback, abs } }) - offset := absOffset + relOffset typ := uint8(linux.DT_REG) if i.produceSymlink { typ = linux.DT_LNK @@ -143,7 +144,7 @@ func (i *fdDirInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, erro // Open implements kernfs.Inode. func (i *fdDirInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) if err != nil { return nil, err } @@ -270,7 +271,7 @@ func (i *fdInfoDirInode) Lookup(ctx context.Context, name string) (*vfs.Dentry, // Open implements kernfs.Inode. func (i *fdInfoDirInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) if err != nil { return nil, err } diff --git a/pkg/sentry/fsimpl/proc/task_files.go b/pkg/sentry/fsimpl/proc/task_files.go index 2f297e48a..859b7d727 100644 --- a/pkg/sentry/fsimpl/proc/task_files.go +++ b/pkg/sentry/fsimpl/proc/task_files.go @@ -22,6 +22,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/safemem" + fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/fsbridge" "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs" "gvisor.dev/gvisor/pkg/sentry/kernel" @@ -34,6 +35,10 @@ import ( "gvisor.dev/gvisor/pkg/usermem" ) +// "There is an (arbitrary) limit on the number of lines in the file. As at +// Linux 3.18, the limit is five lines." - user_namespaces(7) +const maxIDMapLines = 5 + // mm gets the kernel task's MemoryManager. No additional reference is taken on // mm here. This is safe because MemoryManager.destroy is required to leave the // MemoryManager in a state where it's still usable as a DynamicBytesSource. @@ -226,8 +231,9 @@ func (d *cmdlineData) Generate(ctx context.Context, buf *bytes.Buffer) error { // Linux will return envp up to and including the first NULL character, // so find it. - if end := bytes.IndexByte(buf.Bytes()[ar.Length():], 0); end != -1 { - buf.Truncate(end) + envStart := int(ar.Length()) + if nullIdx := bytes.IndexByte(buf.Bytes()[envStart:], 0); nullIdx != -1 { + buf.Truncate(envStart + nullIdx) } } @@ -282,7 +288,8 @@ func (d *commData) Generate(ctx context.Context, buf *bytes.Buffer) error { return nil } -// idMapData implements vfs.DynamicBytesSource for /proc/[pid]/{gid_map|uid_map}. +// idMapData implements vfs.WritableDynamicBytesSource for +// /proc/[pid]/{gid_map|uid_map}. // // +stateify savable type idMapData struct { @@ -294,7 +301,7 @@ type idMapData struct { var _ dynamicInode = (*idMapData)(nil) -// Generate implements vfs.DynamicBytesSource.Generate. +// Generate implements vfs.WritableDynamicBytesSource.Generate. func (d *idMapData) Generate(ctx context.Context, buf *bytes.Buffer) error { var entries []auth.IDMapEntry if d.gids { @@ -308,6 +315,60 @@ func (d *idMapData) Generate(ctx context.Context, buf *bytes.Buffer) error { return nil } +// Write implements vfs.WritableDynamicBytesSource.Write. +func (d *idMapData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) { + // "In addition, the number of bytes written to the file must be less than + // the system page size, and the write must be performed at the start of + // the file ..." - user_namespaces(7) + srclen := src.NumBytes() + if srclen >= usermem.PageSize || offset != 0 { + return 0, syserror.EINVAL + } + b := make([]byte, srclen) + if _, err := src.CopyIn(ctx, b); err != nil { + return 0, err + } + + // Truncate from the first NULL byte. + var nul int64 + nul = int64(bytes.IndexByte(b, 0)) + if nul == -1 { + nul = srclen + } + b = b[:nul] + // Remove the last \n. + if nul >= 1 && b[nul-1] == '\n' { + b = b[:nul-1] + } + lines := bytes.SplitN(b, []byte("\n"), maxIDMapLines+1) + if len(lines) > maxIDMapLines { + return 0, syserror.EINVAL + } + + entries := make([]auth.IDMapEntry, len(lines)) + for i, l := range lines { + var e auth.IDMapEntry + _, err := fmt.Sscan(string(l), &e.FirstID, &e.FirstParentID, &e.Length) + if err != nil { + return 0, syserror.EINVAL + } + entries[i] = e + } + var err error + if d.gids { + err = d.task.UserNamespace().SetGIDMap(ctx, entries) + } else { + err = d.task.UserNamespace().SetUIDMap(ctx, entries) + } + if err != nil { + return 0, err + } + + // On success, Linux's kernel/user_namespace.c:map_write() always returns + // count, even if fewer bytes were used. + return int64(srclen), nil +} + // mapsData implements vfs.DynamicBytesSource for /proc/[pid]/maps. // // +stateify savable @@ -775,6 +836,8 @@ type namespaceInode struct { kernfs.InodeNoopRefCount kernfs.InodeNotDirectory kernfs.InodeNotSymlink + + locks vfs.FileLocks } var _ kernfs.Inode = (*namespaceInode)(nil) @@ -791,6 +854,7 @@ func (i *namespaceInode) Init(creds *auth.Credentials, devMajor, devMinor uint32 func (i *namespaceInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { fd := &namespaceFD{inode: i} i.IncRef() + fd.LockFD.Init(&i.locks) if err := fd.vfsfd.Init(fd, opts.Flags, rp.Mount(), vfsd, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } @@ -801,6 +865,7 @@ func (i *namespaceInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd * // /proc/[pid]/ns/*. type namespaceFD struct { vfs.FileDescriptionDefaultImpl + vfs.LockFD vfsfd vfs.FileDescription inode *namespaceInode @@ -811,7 +876,7 @@ var _ vfs.FileDescriptionImpl = (*namespaceFD)(nil) // Stat implements FileDescriptionImpl. func (fd *namespaceFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) { vfs := fd.vfsfd.VirtualDentry().Mount().Filesystem() - return fd.inode.Stat(vfs, opts) + return fd.inode.Stat(ctx, vfs, opts) } // SetStat implements FileDescriptionImpl. @@ -826,7 +891,12 @@ func (fd *namespaceFD) Release() { fd.inode.DecRef() } -// OnClose implements FileDescriptionImpl. -func (*namespaceFD) OnClose(context.Context) error { - return nil +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *namespaceFD) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *namespaceFD) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) } diff --git a/pkg/sentry/fsimpl/proc/tasks.go b/pkg/sentry/fsimpl/proc/tasks.go index b51d43954..6d2b90a8b 100644 --- a/pkg/sentry/fsimpl/proc/tasks.go +++ b/pkg/sentry/fsimpl/proc/tasks.go @@ -43,6 +43,8 @@ type tasksInode struct { kernfs.OrderedChildren kernfs.AlwaysValid + locks vfs.FileLocks + fs *filesystem pidns *kernel.PIDNamespace @@ -197,15 +199,15 @@ func (i *tasksInode) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback // Open implements kernfs.Inode. func (i *tasksInode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &i.OrderedChildren, &i.locks, &opts) if err != nil { return nil, err } return fd.VFSFileDescription(), nil } -func (i *tasksInode) Stat(vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { - stat, err := i.InodeAttrs.Stat(vsfs, opts) +func (i *tasksInode) Stat(ctx context.Context, vsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) { + stat, err := i.InodeAttrs.Stat(ctx, vsfs, opts) if err != nil { return linux.Statx{}, err } diff --git a/pkg/sentry/fsimpl/signalfd/signalfd.go b/pkg/sentry/fsimpl/signalfd/signalfd.go index d29ef3f83..242ba9b5d 100644 --- a/pkg/sentry/fsimpl/signalfd/signalfd.go +++ b/pkg/sentry/fsimpl/signalfd/signalfd.go @@ -31,6 +31,7 @@ type SignalFileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl vfs.DentryMetadataFileDescriptionImpl + vfs.NoLockFD // target is the original signal target task. // diff --git a/pkg/sentry/fsimpl/sys/BUILD b/pkg/sentry/fsimpl/sys/BUILD index a741e2bb6..1b548ccd4 100644 --- a/pkg/sentry/fsimpl/sys/BUILD +++ b/pkg/sentry/fsimpl/sys/BUILD @@ -29,6 +29,6 @@ go_test( "//pkg/sentry/kernel", "//pkg/sentry/kernel/auth", "//pkg/sentry/vfs", - "@com_github_google_go-cmp//cmp:go_default_library", + "@com_github_google_go_cmp//cmp:go_default_library", ], ) diff --git a/pkg/sentry/fsimpl/sys/sys.go b/pkg/sentry/fsimpl/sys/sys.go index 0af373604..01ce30a4d 100644 --- a/pkg/sentry/fsimpl/sys/sys.go +++ b/pkg/sentry/fsimpl/sys/sys.go @@ -98,8 +98,10 @@ type dir struct { kernfs.InodeNoDynamicLookup kernfs.InodeNotSymlink kernfs.InodeDirectoryNoNewChildren - kernfs.OrderedChildren + + locks vfs.FileLocks + dentry kernfs.Dentry } @@ -121,7 +123,7 @@ func (*dir) SetStat(context.Context, *vfs.Filesystem, *auth.Credentials, vfs.Set // Open implements kernfs.Inode.Open. func (d *dir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &opts) + fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts) if err != nil { return nil, err } @@ -136,7 +138,7 @@ type cpuFile struct { // Generate implements vfs.DynamicBytesSource.Generate. func (c *cpuFile) Generate(ctx context.Context, buf *bytes.Buffer) error { - fmt.Fprintf(buf, "0-%d", c.maxCores-1) + fmt.Fprintf(buf, "0-%d\n", c.maxCores-1) return nil } diff --git a/pkg/sentry/fsimpl/sys/sys_test.go b/pkg/sentry/fsimpl/sys/sys_test.go index 4b3602d47..242d5fd12 100644 --- a/pkg/sentry/fsimpl/sys/sys_test.go +++ b/pkg/sentry/fsimpl/sys/sys_test.go @@ -51,7 +51,7 @@ func TestReadCPUFile(t *testing.T) { k := kernel.KernelFromContext(s.Ctx) maxCPUCores := k.ApplicationCores() - expected := fmt.Sprintf("0-%d", maxCPUCores-1) + expected := fmt.Sprintf("0-%d\n", maxCPUCores-1) for _, fname := range []string{"online", "possible", "present"} { pop := s.PathOpAtRoot(fmt.Sprintf("devices/system/cpu/%s", fname)) diff --git a/pkg/sentry/fsimpl/testutil/BUILD b/pkg/sentry/fsimpl/testutil/BUILD index 0e4053a46..400a97996 100644 --- a/pkg/sentry/fsimpl/testutil/BUILD +++ b/pkg/sentry/fsimpl/testutil/BUILD @@ -32,6 +32,6 @@ go_library( "//pkg/sentry/vfs", "//pkg/sync", "//pkg/usermem", - "@com_github_google_go-cmp//cmp:go_default_library", + "@com_github_google_go_cmp//cmp:go_default_library", ], ) diff --git a/pkg/sentry/fsimpl/testutil/kernel.go b/pkg/sentry/fsimpl/testutil/kernel.go index c16a36cdb..e743e8114 100644 --- a/pkg/sentry/fsimpl/testutil/kernel.go +++ b/pkg/sentry/fsimpl/testutil/kernel.go @@ -62,6 +62,7 @@ func Boot() (*kernel.Kernel, error) { return nil, fmt.Errorf("creating platform: %v", err) } + kernel.VFS2Enabled = true k := &kernel.Kernel{ Platform: plat, } @@ -73,7 +74,7 @@ func Boot() (*kernel.Kernel, error) { k.SetMemoryFile(mf) // Pass k as the platform since it is savable, unlike the actual platform. - vdso, err := loader.PrepareVDSO(nil, k) + vdso, err := loader.PrepareVDSO(k) if err != nil { return nil, fmt.Errorf("creating vdso: %v", err) } @@ -103,11 +104,6 @@ func Boot() (*kernel.Kernel, error) { return nil, fmt.Errorf("initializing kernel: %v", err) } - kernel.VFS2Enabled = true - - if err := k.VFS().Init(); err != nil { - return nil, fmt.Errorf("VFS init: %v", err) - } k.VFS().MustRegisterFilesystemType(tmpfs.Name, &tmpfs.FilesystemType{}, &vfs.RegisterFilesystemTypeOptions{ AllowUserMount: true, AllowUserList: true, diff --git a/pkg/sentry/fsimpl/timerfd/timerfd.go b/pkg/sentry/fsimpl/timerfd/timerfd.go index 60c92d626..2dc90d484 100644 --- a/pkg/sentry/fsimpl/timerfd/timerfd.go +++ b/pkg/sentry/fsimpl/timerfd/timerfd.go @@ -32,6 +32,7 @@ type TimerFileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl vfs.DentryMetadataFileDescriptionImpl + vfs.NoLockFD events waiter.Queue timer *ktime.Timer diff --git a/pkg/sentry/fsimpl/tmpfs/BUILD b/pkg/sentry/fsimpl/tmpfs/BUILD index 007be1572..e73732a6b 100644 --- a/pkg/sentry/fsimpl/tmpfs/BUILD +++ b/pkg/sentry/fsimpl/tmpfs/BUILD @@ -59,9 +59,9 @@ go_library( "//pkg/sentry/pgalloc", "//pkg/sentry/platform", "//pkg/sentry/socket/unix/transport", + "//pkg/sentry/uniqueid", "//pkg/sentry/usage", "//pkg/sentry/vfs", - "//pkg/sentry/vfs/lock", "//pkg/sentry/vfs/memxattr", "//pkg/sync", "//pkg/syserror", diff --git a/pkg/sentry/fsimpl/tmpfs/device_file.go b/pkg/sentry/fsimpl/tmpfs/device_file.go index 83bf885ee..ac54d420d 100644 --- a/pkg/sentry/fsimpl/tmpfs/device_file.go +++ b/pkg/sentry/fsimpl/tmpfs/device_file.go @@ -29,7 +29,7 @@ type deviceFile struct { minor uint32 } -func (fs *filesystem) newDeviceFile(creds *auth.Credentials, mode linux.FileMode, kind vfs.DeviceKind, major, minor uint32) *inode { +func (fs *filesystem) newDeviceFile(kuid auth.KUID, kgid auth.KGID, mode linux.FileMode, kind vfs.DeviceKind, major, minor uint32) *inode { file := &deviceFile{ kind: kind, major: major, @@ -43,7 +43,7 @@ func (fs *filesystem) newDeviceFile(creds *auth.Credentials, mode linux.FileMode default: panic(fmt.Sprintf("invalid DeviceKind: %v", kind)) } - file.inode.init(file, fs, creds, mode) + file.inode.init(file, fs, kuid, kgid, mode) file.inode.nlink = 1 // from parent directory return &file.inode } diff --git a/pkg/sentry/fsimpl/tmpfs/directory.go b/pkg/sentry/fsimpl/tmpfs/directory.go index f2399981b..0a1ad4765 100644 --- a/pkg/sentry/fsimpl/tmpfs/directory.go +++ b/pkg/sentry/fsimpl/tmpfs/directory.go @@ -48,9 +48,9 @@ type directory struct { childList dentryList } -func (fs *filesystem) newDirectory(creds *auth.Credentials, mode linux.FileMode) *directory { +func (fs *filesystem) newDirectory(kuid auth.KUID, kgid auth.KGID, mode linux.FileMode) *directory { dir := &directory{} - dir.inode.init(dir, fs, creds, linux.S_IFDIR|mode) + dir.inode.init(dir, fs, kuid, kgid, linux.S_IFDIR|mode) dir.inode.nlink = 2 // from "." and parent directory or ".." for root dir.dentry.inode = &dir.inode dir.dentry.vfsd.Init(&dir.dentry) @@ -81,6 +81,10 @@ func (dir *directory) removeChildLocked(child *dentry) { dir.iterMu.Unlock() } +func (dir *directory) mayDelete(creds *auth.Credentials, child *dentry) error { + return vfs.CheckDeleteSticky(creds, linux.FileMode(atomic.LoadUint32(&dir.inode.mode)), auth.KUID(atomic.LoadUint32(&child.inode.uid))) +} + type directoryFD struct { fileDescription vfs.DirectoryFileDescriptionDefaultImpl @@ -106,6 +110,8 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba fs := fd.filesystem() dir := fd.inode().impl.(*directory) + defer fd.dentry().InotifyWithParent(linux.IN_ACCESS, 0, vfs.PathEvent) + // fs.mu is required to read d.parent and dentry.name. fs.mu.RLock() defer fs.mu.RUnlock() diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go index 80fa7b29d..ef210a69b 100644 --- a/pkg/sentry/fsimpl/tmpfs/filesystem.go +++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go @@ -79,7 +79,7 @@ afterSymlink: } if symlink, ok := child.inode.impl.(*symlink); ok && rp.ShouldFollowSymlink() { // Symlink traversal updates access time. - atomic.StoreInt64(&d.inode.atime, d.inode.fs.clock.Now().Nanoseconds()) + child.inode.touchAtime(rp.Mount()) if err := rp.HandleSymlink(symlink.target); err != nil { return nil, err } @@ -177,6 +177,12 @@ func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(pa if err := create(parentDir, name); err != nil { return err } + + ev := linux.IN_CREATE + if dir { + ev |= linux.IN_ISDIR + } + parentDir.inode.watches.Notify(name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */) parentDir.inode.touchCMtime() return nil } @@ -231,17 +237,22 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs. return syserror.EXDEV } d := vd.Dentry().Impl().(*dentry) - if d.inode.isDir() { + i := d.inode + if i.isDir() { return syserror.EPERM } - if d.inode.nlink == 0 { + if err := vfs.MayLink(auth.CredentialsFromContext(ctx), linux.FileMode(atomic.LoadUint32(&i.mode)), auth.KUID(atomic.LoadUint32(&i.uid)), auth.KGID(atomic.LoadUint32(&i.gid))); err != nil { + return err + } + if i.nlink == 0 { return syserror.ENOENT } - if d.inode.nlink == maxLinks { + if i.nlink == maxLinks { return syserror.EMLINK } - d.inode.incLinksLocked() - parentDir.insertChildLocked(fs.newDentry(d.inode), name) + i.incLinksLocked() + i.watches.Notify("", linux.IN_ATTRIB, 0, vfs.InodeEvent, false /* unlinked */) + parentDir.insertChildLocked(fs.newDentry(i), name) return nil }) } @@ -249,11 +260,12 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs. // MkdirAt implements vfs.FilesystemImpl.MkdirAt. func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error { return fs.doCreateAt(rp, true /* dir */, func(parentDir *directory, name string) error { + creds := rp.Credentials() if parentDir.inode.nlink == maxLinks { return syserror.EMLINK } parentDir.inode.incLinksLocked() // from child's ".." - childDir := fs.newDirectory(rp.Credentials(), opts.Mode) + childDir := fs.newDirectory(creds.EffectiveKUID, creds.EffectiveKGID, opts.Mode) parentDir.insertChildLocked(&childDir.dentry, name) return nil }) @@ -262,18 +274,19 @@ func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v // MknodAt implements vfs.FilesystemImpl.MknodAt. func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error { return fs.doCreateAt(rp, false /* dir */, func(parentDir *directory, name string) error { + creds := rp.Credentials() var childInode *inode switch opts.Mode.FileType() { - case 0, linux.S_IFREG: - childInode = fs.newRegularFile(rp.Credentials(), opts.Mode) + case linux.S_IFREG: + childInode = fs.newRegularFile(creds.EffectiveKUID, creds.EffectiveKGID, opts.Mode) case linux.S_IFIFO: - childInode = fs.newNamedPipe(rp.Credentials(), opts.Mode) + childInode = fs.newNamedPipe(creds.EffectiveKUID, creds.EffectiveKGID, opts.Mode) case linux.S_IFBLK: - childInode = fs.newDeviceFile(rp.Credentials(), opts.Mode, vfs.BlockDevice, opts.DevMajor, opts.DevMinor) + childInode = fs.newDeviceFile(creds.EffectiveKUID, creds.EffectiveKGID, opts.Mode, vfs.BlockDevice, opts.DevMajor, opts.DevMinor) case linux.S_IFCHR: - childInode = fs.newDeviceFile(rp.Credentials(), opts.Mode, vfs.CharDevice, opts.DevMajor, opts.DevMinor) + childInode = fs.newDeviceFile(creds.EffectiveKUID, creds.EffectiveKGID, opts.Mode, vfs.CharDevice, opts.DevMajor, opts.DevMinor) case linux.S_IFSOCK: - childInode = fs.newSocketFile(rp.Credentials(), opts.Mode, opts.Endpoint) + childInode = fs.newSocketFile(creds.EffectiveKUID, creds.EffectiveKGID, opts.Mode, opts.Endpoint) default: return syserror.EINVAL } @@ -348,15 +361,20 @@ afterTrailingSymlink: } defer rp.Mount().EndWrite() // Create and open the child. - child := fs.newDentry(fs.newRegularFile(rp.Credentials(), opts.Mode)) + creds := rp.Credentials() + child := fs.newDentry(fs.newRegularFile(creds.EffectiveKUID, creds.EffectiveKGID, opts.Mode)) parentDir.insertChildLocked(child, name) fd, err := child.open(ctx, rp, &opts, true) if err != nil { return nil, err } + parentDir.inode.watches.Notify(name, linux.IN_CREATE, 0, vfs.PathEvent, false /* unlinked */) parentDir.inode.touchCMtime() return fd, nil } + if mustCreate { + return nil, syserror.EEXIST + } // Is the file mounted over? if err := rp.CheckMount(&child.vfsd); err != nil { return nil, err @@ -364,7 +382,7 @@ afterTrailingSymlink: // Do we need to resolve a trailing symlink? if symlink, ok := child.inode.impl.(*symlink); ok && rp.ShouldFollowSymlink() { // Symlink traversal updates access time. - atomic.StoreInt64(&child.inode.atime, child.inode.fs.clock.Now().Nanoseconds()) + child.inode.touchAtime(rp.Mount()) if err := rp.HandleSymlink(symlink.target); err != nil { return nil, err } @@ -388,10 +406,11 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.Open switch impl := d.inode.impl.(type) { case *regularFile: var fd regularFileFD - if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { + fd.LockFD.Init(&d.inode.locks) + if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{AllowDirectIO: true}); err != nil { return nil, err } - if opts.Flags&linux.O_TRUNC != 0 { + if !afterCreate && opts.Flags&linux.O_TRUNC != 0 { if _, err := impl.truncate(0); err != nil { return nil, err } @@ -403,15 +422,16 @@ func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.Open return nil, syserror.EISDIR } var fd directoryFD - if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { + fd.LockFD.Init(&d.inode.locks) + if err := fd.vfsfd.Init(&fd, opts.Flags, rp.Mount(), &d.vfsd, &vfs.FileDescriptionOptions{AllowDirectIO: true}); err != nil { return nil, err } return &fd.vfsfd, nil case *symlink: - // Can't open symlinks without O_PATH (which is unimplemented). + // TODO(gvisor.dev/issue/2782): Can't open symlinks without O_PATH. return nil, syserror.ELOOP case *namedPipe: - return impl.pipe.Open(ctx, rp.Mount(), &d.vfsd, opts.Flags) + return impl.pipe.Open(ctx, rp.Mount(), &d.vfsd, opts.Flags, &d.inode.locks) case *deviceFile: return rp.VirtualFilesystem().OpenDeviceSpecialFile(ctx, rp.Mount(), &d.vfsd, impl.kind, impl.major, impl.minor, opts) case *socketFile: @@ -472,6 +492,9 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa if !ok { return syserror.ENOENT } + if err := oldParentDir.mayDelete(rp.Credentials(), renamed); err != nil { + return err + } // Note that we don't need to call rp.CheckMount(), since if renamed is a // mount point then we want to rename the mount point, not anything in the // mounted filesystem. @@ -559,6 +582,8 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa newParentDir.inode.touchCMtime() } renamed.inode.touchCtime() + + vfs.InotifyRename(ctx, &renamed.inode.watches, &oldParentDir.inode.watches, &newParentDir.inode.watches, oldName, newName, renamed.inode.isDir()) return nil } @@ -584,6 +609,9 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error if !ok { return syserror.ENOENT } + if err := parentDir.mayDelete(rp.Credentials(), child); err != nil { + return err + } childDir, ok := child.inode.impl.(*directory) if !ok { return syserror.ENOTDIR @@ -603,8 +631,11 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error return err } parentDir.removeChildLocked(child) - parentDir.inode.decLinksLocked() // from child's ".." + parentDir.inode.watches.Notify(name, linux.IN_DELETE|linux.IN_ISDIR, 0, vfs.InodeEvent, true /* unlinked */) + // Remove links for child, child/., and child/.. + child.inode.decLinksLocked() child.inode.decLinksLocked() + parentDir.inode.decLinksLocked() vfsObj.CommitDeleteDentry(&child.vfsd) parentDir.inode.touchCMtime() return nil @@ -613,12 +644,21 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error // SetStatAt implements vfs.FilesystemImpl.SetStatAt. func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { fs.mu.RLock() - defer fs.mu.RUnlock() d, err := resolveLocked(rp) if err != nil { + fs.mu.RUnlock() + return err + } + if err := d.inode.setStat(ctx, rp.Credentials(), &opts); err != nil { + fs.mu.RUnlock() return err } - return d.inode.setStat(ctx, rp.Credentials(), &opts.Stat) + fs.mu.RUnlock() + + if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { + d.InotifyWithParent(ev, 0, vfs.InodeEvent) + } + return nil } // StatAt implements vfs.FilesystemImpl.StatAt. @@ -656,7 +696,8 @@ func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linu // SymlinkAt implements vfs.FilesystemImpl.SymlinkAt. func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error { return fs.doCreateAt(rp, false /* dir */, func(parentDir *directory, name string) error { - child := fs.newDentry(fs.newSymlink(rp.Credentials(), target)) + creds := rp.Credentials() + child := fs.newDentry(fs.newSymlink(creds.EffectiveKUID, creds.EffectiveKGID, 0777, target)) parentDir.insertChildLocked(child, name) return nil }) @@ -681,6 +722,9 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error if !ok { return syserror.ENOENT } + if err := parentDir.mayDelete(rp.Credentials(), child); err != nil { + return err + } if child.inode.isDir() { return syserror.EISDIR } @@ -698,6 +742,12 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil { return err } + + // Generate inotify events. Note that this must take place before the link + // count of the child is decremented, or else the watches may be dropped + // before these events are added. + vfs.InotifyRemoveChild(&child.inode.watches, &parentDir.inode.watches, name) + parentDir.removeChildLocked(child) child.inode.decLinksLocked() vfsObj.CommitDeleteDentry(&child.vfsd) @@ -749,23 +799,37 @@ func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt // SetxattrAt implements vfs.FilesystemImpl.SetxattrAt. func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error { fs.mu.RLock() - defer fs.mu.RUnlock() d, err := resolveLocked(rp) if err != nil { + fs.mu.RUnlock() + return err + } + if err := d.inode.setxattr(rp.Credentials(), &opts); err != nil { + fs.mu.RUnlock() return err } - return d.inode.setxattr(rp.Credentials(), &opts) + fs.mu.RUnlock() + + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // RemovexattrAt implements vfs.FilesystemImpl.RemovexattrAt. func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error { fs.mu.RLock() - defer fs.mu.RUnlock() d, err := resolveLocked(rp) if err != nil { + fs.mu.RUnlock() return err } - return d.inode.removexattr(rp.Credentials(), name) + if err := d.inode.removexattr(rp.Credentials(), name); err != nil { + fs.mu.RUnlock() + return err + } + fs.mu.RUnlock() + + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // PrependPath implements vfs.FilesystemImpl.PrependPath. diff --git a/pkg/sentry/fsimpl/tmpfs/named_pipe.go b/pkg/sentry/fsimpl/tmpfs/named_pipe.go index 8d77b3fa8..739350cf0 100644 --- a/pkg/sentry/fsimpl/tmpfs/named_pipe.go +++ b/pkg/sentry/fsimpl/tmpfs/named_pipe.go @@ -30,9 +30,9 @@ type namedPipe struct { // Preconditions: // * fs.mu must be locked. // * rp.Mount().CheckBeginWrite() has been called successfully. -func (fs *filesystem) newNamedPipe(creds *auth.Credentials, mode linux.FileMode) *inode { +func (fs *filesystem) newNamedPipe(kuid auth.KUID, kgid auth.KGID, mode linux.FileMode) *inode { file := &namedPipe{pipe: pipe.NewVFSPipe(true /* isNamed */, pipe.DefaultPipeSize, usermem.PageSize)} - file.inode.init(file, fs, creds, linux.S_IFIFO|mode) + file.inode.init(file, fs, kuid, kgid, linux.S_IFIFO|mode) file.inode.nlink = 1 // Only the parent has a link. return &file.inode } diff --git a/pkg/sentry/fsimpl/tmpfs/regular_file.go b/pkg/sentry/fsimpl/tmpfs/regular_file.go index 3f433d666..abbaa5d60 100644 --- a/pkg/sentry/fsimpl/tmpfs/regular_file.go +++ b/pkg/sentry/fsimpl/tmpfs/regular_file.go @@ -25,7 +25,6 @@ import ( "gvisor.dev/gvisor/pkg/safemem" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" - "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/sentry/pgalloc" @@ -85,12 +84,12 @@ type regularFile struct { size uint64 } -func (fs *filesystem) newRegularFile(creds *auth.Credentials, mode linux.FileMode) *inode { +func (fs *filesystem) newRegularFile(kuid auth.KUID, kgid auth.KGID, mode linux.FileMode) *inode { file := ®ularFile{ memFile: fs.memFile, seals: linux.F_SEAL_SEAL, } - file.inode.init(file, fs, creds, linux.S_IFREG|mode) + file.inode.init(file, fs, kuid, kgid, linux.S_IFREG|mode) file.inode.nlink = 1 // from parent directory return &file.inode } @@ -275,11 +274,35 @@ func (fd *regularFileFD) Release() { // noop } +// Allocate implements vfs.FileDescriptionImpl.Allocate. +func (fd *regularFileFD) Allocate(ctx context.Context, mode, offset, length uint64) error { + f := fd.inode().impl.(*regularFile) + + f.inode.mu.Lock() + defer f.inode.mu.Unlock() + oldSize := f.size + size := offset + length + if oldSize >= size { + return nil + } + _, err := f.truncateLocked(size) + return err +} + // PRead implements vfs.FileDescriptionImpl.PRead. func (fd *regularFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) { if offset < 0 { return 0, syserror.EINVAL } + + // Check that flags are supported. RWF_DSYNC/RWF_SYNC can be ignored since + // all state is in-memory. + // + // TODO(gvisor.dev/issue/2601): Support select preadv2 flags. + if opts.Flags&^(linux.RWF_HIPRI|linux.RWF_DSYNC|linux.RWF_SYNC) != 0 { + return 0, syserror.EOPNOTSUPP + } + if dst.NumBytes() == 0 { return 0, nil } @@ -302,40 +325,60 @@ func (fd *regularFileFD) Read(ctx context.Context, dst usermem.IOSequence, opts // PWrite implements vfs.FileDescriptionImpl.PWrite. func (fd *regularFileFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) { + n, _, err := fd.pwrite(ctx, src, offset, opts) + return n, err +} + +// pwrite returns the number of bytes written, final offset and error. The +// final offset should be ignored by PWrite. +func (fd *regularFileFD) pwrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (written, finalOff int64, err error) { if offset < 0 { - return 0, syserror.EINVAL + return 0, offset, syserror.EINVAL } + + // Check that flags are supported. RWF_DSYNC/RWF_SYNC can be ignored since + // all state is in-memory. + // + // TODO(gvisor.dev/issue/2601): Support select preadv2 flags. + if opts.Flags&^(linux.RWF_HIPRI|linux.RWF_DSYNC|linux.RWF_SYNC) != 0 { + return 0, offset, syserror.EOPNOTSUPP + } + srclen := src.NumBytes() if srclen == 0 { - return 0, nil + return 0, offset, nil } f := fd.inode().impl.(*regularFile) + f.inode.mu.Lock() + defer f.inode.mu.Unlock() + // If the file is opened with O_APPEND, update offset to file size. + if fd.vfsfd.StatusFlags()&linux.O_APPEND != 0 { + // Locking f.inode.mu is sufficient for reading f.size. + offset = int64(f.size) + } if end := offset + srclen; end < offset { // Overflow. - return 0, syserror.EFBIG + return 0, offset, syserror.EINVAL } - var err error srclen, err = vfs.CheckLimit(ctx, offset, srclen) if err != nil { - return 0, err + return 0, offset, err } src = src.TakeFirst64(srclen) - f.inode.mu.Lock() rw := getRegularFileReadWriter(f, offset) n, err := src.CopyInTo(ctx, rw) - fd.inode().touchCMtimeLocked() - f.inode.mu.Unlock() + f.inode.touchCMtimeLocked() putRegularFileReadWriter(rw) - return n, err + return n, n + offset, err } // Write implements vfs.FileDescriptionImpl.Write. func (fd *regularFileFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) { fd.offMu.Lock() - n, err := fd.PWrite(ctx, src, fd.off, opts) - fd.off += n + n, off, err := fd.pwrite(ctx, src, fd.off, opts) + fd.off = off fd.offMu.Unlock() return n, err } @@ -361,33 +404,6 @@ func (fd *regularFileFD) Seek(ctx context.Context, offset int64, whence int32) ( return offset, nil } -// Sync implements vfs.FileDescriptionImpl.Sync. -func (fd *regularFileFD) Sync(ctx context.Context) error { - return nil -} - -// LockBSD implements vfs.FileDescriptionImpl.LockBSD. -func (fd *regularFileFD) LockBSD(ctx context.Context, uid lock.UniqueID, t lock.LockType, block lock.Blocker) error { - return fd.inode().lockBSD(uid, t, block) -} - -// UnlockBSD implements vfs.FileDescriptionImpl.UnlockBSD. -func (fd *regularFileFD) UnlockBSD(ctx context.Context, uid lock.UniqueID) error { - fd.inode().unlockBSD(uid) - return nil -} - -// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. -func (fd *regularFileFD) LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, rng lock.LockRange, block lock.Blocker) error { - return fd.inode().lockPOSIX(uid, t, rng, block) -} - -// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. -func (fd *regularFileFD) UnlockPOSIX(ctx context.Context, uid lock.UniqueID, rng lock.LockRange) error { - fd.inode().unlockPOSIX(uid, rng) - return nil -} - // ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap. func (fd *regularFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error { file := fd.inode().impl.(*regularFile) diff --git a/pkg/sentry/fsimpl/tmpfs/regular_file_test.go b/pkg/sentry/fsimpl/tmpfs/regular_file_test.go index 64e1c40ad..146c7fdfe 100644 --- a/pkg/sentry/fsimpl/tmpfs/regular_file_test.go +++ b/pkg/sentry/fsimpl/tmpfs/regular_file_test.go @@ -138,48 +138,37 @@ func TestLocks(t *testing.T) { } defer cleanup() - var ( - uid1 lock.UniqueID - uid2 lock.UniqueID - // Non-blocking. - block lock.Blocker - ) - - uid1 = 123 - uid2 = 456 - - if err := fd.Impl().LockBSD(ctx, uid1, lock.ReadLock, block); err != nil { + uid1 := 123 + uid2 := 456 + if err := fd.Impl().LockBSD(ctx, uid1, lock.ReadLock, nil); err != nil { t.Fatalf("fd.Impl().LockBSD failed: err = %v", err) } - if err := fd.Impl().LockBSD(ctx, uid2, lock.ReadLock, block); err != nil { + if err := fd.Impl().LockBSD(ctx, uid2, lock.ReadLock, nil); err != nil { t.Fatalf("fd.Impl().LockBSD failed: err = %v", err) } - if got, want := fd.Impl().LockBSD(ctx, uid2, lock.WriteLock, block), syserror.ErrWouldBlock; got != want { + if got, want := fd.Impl().LockBSD(ctx, uid2, lock.WriteLock, nil), syserror.ErrWouldBlock; got != want { t.Fatalf("fd.Impl().LockBSD failed: got = %v, want = %v", got, want) } if err := fd.Impl().UnlockBSD(ctx, uid1); err != nil { t.Fatalf("fd.Impl().UnlockBSD failed: err = %v", err) } - if err := fd.Impl().LockBSD(ctx, uid2, lock.WriteLock, block); err != nil { + if err := fd.Impl().LockBSD(ctx, uid2, lock.WriteLock, nil); err != nil { t.Fatalf("fd.Impl().LockBSD failed: err = %v", err) } - rng1 := lock.LockRange{0, 1} - rng2 := lock.LockRange{1, 2} - - if err := fd.Impl().LockPOSIX(ctx, uid1, lock.ReadLock, rng1, block); err != nil { + if err := fd.Impl().LockPOSIX(ctx, uid1, lock.ReadLock, 0, 1, linux.SEEK_SET, nil); err != nil { t.Fatalf("fd.Impl().LockPOSIX failed: err = %v", err) } - if err := fd.Impl().LockPOSIX(ctx, uid2, lock.ReadLock, rng2, block); err != nil { + if err := fd.Impl().LockPOSIX(ctx, uid2, lock.ReadLock, 1, 2, linux.SEEK_SET, nil); err != nil { t.Fatalf("fd.Impl().LockPOSIX failed: err = %v", err) } - if err := fd.Impl().LockPOSIX(ctx, uid1, lock.WriteLock, rng1, block); err != nil { + if err := fd.Impl().LockPOSIX(ctx, uid1, lock.WriteLock, 0, 1, linux.SEEK_SET, nil); err != nil { t.Fatalf("fd.Impl().LockPOSIX failed: err = %v", err) } - if got, want := fd.Impl().LockPOSIX(ctx, uid2, lock.ReadLock, rng1, block), syserror.ErrWouldBlock; got != want { + if got, want := fd.Impl().LockPOSIX(ctx, uid2, lock.ReadLock, 0, 1, linux.SEEK_SET, nil), syserror.ErrWouldBlock; got != want { t.Fatalf("fd.Impl().LockPOSIX failed: got = %v, want = %v", got, want) } - if err := fd.Impl().UnlockPOSIX(ctx, uid1, rng1); err != nil { + if err := fd.Impl().UnlockPOSIX(ctx, uid1, 0, 1, linux.SEEK_SET); err != nil { t.Fatalf("fd.Impl().UnlockPOSIX failed: err = %v", err) } } diff --git a/pkg/sentry/fsimpl/tmpfs/socket_file.go b/pkg/sentry/fsimpl/tmpfs/socket_file.go index 25c2321af..3ed650474 100644 --- a/pkg/sentry/fsimpl/tmpfs/socket_file.go +++ b/pkg/sentry/fsimpl/tmpfs/socket_file.go @@ -26,9 +26,9 @@ type socketFile struct { ep transport.BoundEndpoint } -func (fs *filesystem) newSocketFile(creds *auth.Credentials, mode linux.FileMode, ep transport.BoundEndpoint) *inode { +func (fs *filesystem) newSocketFile(kuid auth.KUID, kgid auth.KGID, mode linux.FileMode, ep transport.BoundEndpoint) *inode { file := &socketFile{ep: ep} - file.inode.init(file, fs, creds, mode) + file.inode.init(file, fs, kuid, kgid, mode) file.inode.nlink = 1 // from parent directory return &file.inode } diff --git a/pkg/sentry/fsimpl/tmpfs/symlink.go b/pkg/sentry/fsimpl/tmpfs/symlink.go index 47e075ed4..b0de5fabe 100644 --- a/pkg/sentry/fsimpl/tmpfs/symlink.go +++ b/pkg/sentry/fsimpl/tmpfs/symlink.go @@ -24,11 +24,11 @@ type symlink struct { target string // immutable } -func (fs *filesystem) newSymlink(creds *auth.Credentials, target string) *inode { +func (fs *filesystem) newSymlink(kuid auth.KUID, kgid auth.KGID, mode linux.FileMode, target string) *inode { link := &symlink{ target: target, } - link.inode.init(link, fs, creds, linux.S_IFLNK|0777) + link.inode.init(link, fs, kuid, kgid, linux.S_IFLNK|mode) link.inode.nlink = 1 // from parent directory return &link.inode } diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go index 1e781aecd..2545d88e9 100644 --- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go +++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go @@ -30,6 +30,7 @@ package tmpfs import ( "fmt" "math" + "strconv" "strings" "sync/atomic" @@ -40,7 +41,6 @@ import ( "gvisor.dev/gvisor/pkg/sentry/kernel/time" "gvisor.dev/gvisor/pkg/sentry/pgalloc" "gvisor.dev/gvisor/pkg/sentry/vfs" - "gvisor.dev/gvisor/pkg/sentry/vfs/lock" "gvisor.dev/gvisor/pkg/sentry/vfs/memxattr" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/syserror" @@ -112,6 +112,58 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt } } + mopts := vfs.GenericParseMountOptions(opts.Data) + rootMode := linux.FileMode(0777) + if rootFileType == linux.S_IFDIR { + rootMode = 01777 + } + modeStr, ok := mopts["mode"] + if ok { + delete(mopts, "mode") + mode, err := strconv.ParseUint(modeStr, 8, 32) + if err != nil { + ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: invalid mode: %q", modeStr) + return nil, nil, syserror.EINVAL + } + rootMode = linux.FileMode(mode & 07777) + } + rootKUID := creds.EffectiveKUID + uidStr, ok := mopts["uid"] + if ok { + delete(mopts, "uid") + uid, err := strconv.ParseUint(uidStr, 10, 32) + if err != nil { + ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: invalid uid: %q", uidStr) + return nil, nil, syserror.EINVAL + } + kuid := creds.UserNamespace.MapToKUID(auth.UID(uid)) + if !kuid.Ok() { + ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: unmapped uid: %d", uid) + return nil, nil, syserror.EINVAL + } + rootKUID = kuid + } + rootKGID := creds.EffectiveKGID + gidStr, ok := mopts["gid"] + if ok { + delete(mopts, "gid") + gid, err := strconv.ParseUint(gidStr, 10, 32) + if err != nil { + ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: invalid gid: %q", gidStr) + return nil, nil, syserror.EINVAL + } + kgid := creds.UserNamespace.MapToKGID(auth.GID(gid)) + if !kgid.Ok() { + ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: unmapped gid: %d", gid) + return nil, nil, syserror.EINVAL + } + rootKGID = kgid + } + if len(mopts) != 0 { + ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: unknown options: %v", mopts) + return nil, nil, syserror.EINVAL + } + devMinor, err := vfsObj.GetAnonBlockDevMinor() if err != nil { return nil, nil, err @@ -127,11 +179,11 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt var root *dentry switch rootFileType { case linux.S_IFREG: - root = fs.newDentry(fs.newRegularFile(creds, 0777)) + root = fs.newDentry(fs.newRegularFile(rootKUID, rootKGID, rootMode)) case linux.S_IFLNK: - root = fs.newDentry(fs.newSymlink(creds, tmpfsOpts.RootSymlinkTarget)) + root = fs.newDentry(fs.newSymlink(rootKUID, rootKGID, rootMode, tmpfsOpts.RootSymlinkTarget)) case linux.S_IFDIR: - root = &fs.newDirectory(creds, 01777).dentry + root = &fs.newDirectory(rootKUID, rootKGID, rootMode).dentry default: fs.vfsfs.DecRef() return nil, nil, fmt.Errorf("invalid tmpfs root file type: %#o", rootFileType) @@ -201,6 +253,33 @@ func (d *dentry) DecRef() { d.inode.decRef() } +// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. +func (d *dentry) InotifyWithParent(events, cookie uint32, et vfs.EventType) { + if d.inode.isDir() { + events |= linux.IN_ISDIR + } + + // tmpfs never calls VFS.InvalidateDentry(), so d.vfsd.IsDead() indicates + // that d was deleted. + deleted := d.vfsd.IsDead() + + d.inode.fs.mu.RLock() + // The ordering below is important, Linux always notifies the parent first. + if d.parent != nil { + d.parent.inode.watches.Notify(d.name, events, cookie, et, deleted) + } + d.inode.watches.Notify("", events, cookie, et, deleted) + d.inode.fs.mu.RUnlock() +} + +// Watches implements vfs.DentryImpl.Watches. +func (d *dentry) Watches() *vfs.Watches { + return &d.inode.watches +} + +// OnZeroWatches implements vfs.Dentry.OnZeroWatches. +func (d *dentry) OnZeroWatches() {} + // inode represents a filesystem object. type inode struct { // fs is the owning filesystem. fs is immutable. @@ -209,11 +288,9 @@ type inode struct { // refs is a reference count. refs is accessed using atomic memory // operations. // - // A reference is held on all inodes that are reachable in the filesystem - // tree. For non-directories (which may have multiple hard links), this - // means that a reference is dropped when nlink reaches 0. For directories, - // nlink never reaches 0 due to the "." entry; instead, - // filesystem.RmdirAt() drops the reference. + // A reference is held on all inodes as long as they are reachable in the + // filesystem tree, i.e. nlink is nonzero. This reference is dropped when + // nlink reaches 0. refs int64 // xattrs implements extended attributes. @@ -235,23 +312,25 @@ type inode struct { ctime int64 // nanoseconds mtime int64 // nanoseconds - // Advisory file locks, which lock at the inode level. - locks lock.FileLocks + locks vfs.FileLocks + + // Inotify watches for this inode. + watches vfs.Watches impl interface{} // immutable } const maxLinks = math.MaxUint32 -func (i *inode) init(impl interface{}, fs *filesystem, creds *auth.Credentials, mode linux.FileMode) { +func (i *inode) init(impl interface{}, fs *filesystem, kuid auth.KUID, kgid auth.KGID, mode linux.FileMode) { if mode.FileType() == 0 { panic("file type is required in FileMode") } i.fs = fs i.refs = 1 i.mode = uint32(mode) - i.uid = uint32(creds.EffectiveKUID) - i.gid = uint32(creds.EffectiveKGID) + i.uid = uint32(kuid) + i.gid = uint32(kgid) i.ino = atomic.AddUint64(&fs.nextInoMinusOne, 1) // Tmpfs creation sets atime, ctime, and mtime to current time. now := fs.clock.Now().Nanoseconds() @@ -276,14 +355,17 @@ func (i *inode) incLinksLocked() { atomic.AddUint32(&i.nlink, 1) } -// decLinksLocked decrements i's link count. +// decLinksLocked decrements i's link count. If the link count reaches 0, we +// remove a reference on i as well. // // Preconditions: filesystem.mu must be locked for writing. i.nlink != 0. func (i *inode) decLinksLocked() { if i.nlink == 0 { panic("tmpfs.inode.decLinksLocked() called with no existing links") } - atomic.AddUint32(&i.nlink, ^uint32(0)) + if atomic.AddUint32(&i.nlink, ^uint32(0)) == 0 { + i.decRef() + } } func (i *inode) incRef() { @@ -306,6 +388,7 @@ func (i *inode) tryIncRef() bool { func (i *inode) decRef() { if refs := atomic.AddInt64(&i.refs, -1); refs == 0 { + i.watches.HandleDeletion() if regFile, ok := i.impl.(*regularFile); ok { // Release memory used by regFile to store data. Since regFile is // no longer usable, we don't need to grab any locks or update any @@ -369,7 +452,8 @@ func (i *inode) statTo(stat *linux.Statx) { } } -func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linux.Statx) error { +func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, opts *vfs.SetStatOptions) error { + stat := &opts.Stat if stat.Mask == 0 { return nil } @@ -377,7 +461,7 @@ func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linu return syserror.EPERM } mode := linux.FileMode(atomic.LoadUint32(&i.mode)) - if err := vfs.CheckSetStat(ctx, creds, stat, mode, auth.KUID(atomic.LoadUint32(&i.uid)), auth.KGID(atomic.LoadUint32(&i.gid))); err != nil { + if err := vfs.CheckSetStat(ctx, creds, opts, mode, auth.KUID(atomic.LoadUint32(&i.uid)), auth.KGID(atomic.LoadUint32(&i.gid))); err != nil { return err } i.mu.Lock() @@ -455,44 +539,6 @@ func (i *inode) setStat(ctx context.Context, creds *auth.Credentials, stat *linu return nil } -// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular. -func (i *inode) lockBSD(uid fslock.UniqueID, t fslock.LockType, block fslock.Blocker) error { - switch i.impl.(type) { - case *regularFile: - return i.locks.LockBSD(uid, t, block) - } - return syserror.EBADF -} - -// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular. -func (i *inode) unlockBSD(uid fslock.UniqueID) error { - switch i.impl.(type) { - case *regularFile: - i.locks.UnlockBSD(uid) - return nil - } - return syserror.EBADF -} - -// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular. -func (i *inode) lockPOSIX(uid fslock.UniqueID, t fslock.LockType, rng fslock.LockRange, block fslock.Blocker) error { - switch i.impl.(type) { - case *regularFile: - return i.locks.LockPOSIX(uid, t, rng, block) - } - return syserror.EBADF -} - -// TODO(gvisor.dev/issue/1480): support file locking for file types other than regular. -func (i *inode) unlockPOSIX(uid fslock.UniqueID, rng fslock.LockRange) error { - switch i.impl.(type) { - case *regularFile: - i.locks.UnlockPOSIX(uid, rng) - return nil - } - return syserror.EBADF -} - // allocatedBlocksForSize returns the number of 512B blocks needed to // accommodate the given size in bytes, as appropriate for struct // stat::st_blocks and struct statx::stx_blocks. (Note that this 512B block @@ -531,6 +577,9 @@ func (i *inode) isDir() bool { } func (i *inode) touchAtime(mnt *vfs.Mount) { + if mnt.Flags.NoATime { + return + } if err := mnt.CheckBeginWrite(); err != nil { return } @@ -621,14 +670,19 @@ func (i *inode) userXattrSupported() bool { type fileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl + vfs.LockFD } func (fd *fileDescription) filesystem() *filesystem { return fd.vfsfd.Mount().Filesystem().Impl().(*filesystem) } +func (fd *fileDescription) dentry() *dentry { + return fd.vfsfd.Dentry().Impl().(*dentry) +} + func (fd *fileDescription) inode() *inode { - return fd.vfsfd.Dentry().Impl().(*dentry).inode + return fd.dentry().inode } // Stat implements vfs.FileDescriptionImpl.Stat. @@ -641,7 +695,15 @@ func (fd *fileDescription) Stat(ctx context.Context, opts vfs.StatOptions) (linu // SetStat implements vfs.FileDescriptionImpl.SetStat. func (fd *fileDescription) SetStat(ctx context.Context, opts vfs.SetStatOptions) error { creds := auth.CredentialsFromContext(ctx) - return fd.inode().setStat(ctx, creds, &opts.Stat) + d := fd.dentry() + if err := d.inode.setStat(ctx, creds, &opts); err != nil { + return err + } + + if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { + d.InotifyWithParent(ev, 0, vfs.InodeEvent) + } + return nil } // Listxattr implements vfs.FileDescriptionImpl.Listxattr. @@ -656,12 +718,26 @@ func (fd *fileDescription) Getxattr(ctx context.Context, opts vfs.GetxattrOption // Setxattr implements vfs.FileDescriptionImpl.Setxattr. func (fd *fileDescription) Setxattr(ctx context.Context, opts vfs.SetxattrOptions) error { - return fd.inode().setxattr(auth.CredentialsFromContext(ctx), &opts) + d := fd.dentry() + if err := d.inode.setxattr(auth.CredentialsFromContext(ctx), &opts); err != nil { + return err + } + + // Generate inotify events. + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // Removexattr implements vfs.FileDescriptionImpl.Removexattr. func (fd *fileDescription) Removexattr(ctx context.Context, name string) error { - return fd.inode().removexattr(auth.CredentialsFromContext(ctx), name) + d := fd.dentry() + if err := d.inode.removexattr(auth.CredentialsFromContext(ctx), name); err != nil { + return err + } + + // Generate inotify events. + d.InotifyWithParent(linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // NewMemfd creates a new tmpfs regular file and file description that can back @@ -674,8 +750,7 @@ func NewMemfd(mount *vfs.Mount, creds *auth.Credentials, allowSeals bool, name s // Per Linux, mm/shmem.c:__shmem_file_setup(), memfd inodes are set up with // S_IRWXUGO. - mode := linux.FileMode(0777) - inode := fs.newRegularFile(creds, mode) + inode := fs.newRegularFile(creds.EffectiveKUID, creds.EffectiveKGID, 0777) rf := inode.impl.(*regularFile) if allowSeals { rf.seals = 0 @@ -688,9 +763,26 @@ func NewMemfd(mount *vfs.Mount, creds *auth.Credentials, allowSeals bool, name s // Per Linux, mm/shmem.c:__shmem_file_setup(), memfd files are set up with // FMODE_READ | FMODE_WRITE. var fd regularFileFD + fd.Init(&inode.locks) flags := uint32(linux.O_RDWR) if err := fd.vfsfd.Init(&fd, flags, mount, &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil { return nil, err } return &fd.vfsfd, nil } + +// LockPOSIX implements vfs.FileDescriptionImpl.LockPOSIX. +func (fd *fileDescription) LockPOSIX(ctx context.Context, uid fslock.UniqueID, t fslock.LockType, start, length uint64, whence int16, block fslock.Blocker) error { + return fd.Locks().LockPOSIX(ctx, &fd.vfsfd, uid, t, start, length, whence, block) +} + +// UnlockPOSIX implements vfs.FileDescriptionImpl.UnlockPOSIX. +func (fd *fileDescription) UnlockPOSIX(ctx context.Context, uid fslock.UniqueID, start, length uint64, whence int16) error { + return fd.Locks().UnlockPOSIX(ctx, &fd.vfsfd, uid, start, length, whence) +} + +// Sync implements vfs.FileDescriptionImpl.Sync. It does nothing because all +// filesystem state is in-memory. +func (*fileDescription) Sync(context.Context) error { + return nil +} |