diff options
Diffstat (limited to 'pkg/sentry/fsimpl/ext/filesystem.go')
| -rw-r--r-- | pkg/sentry/fsimpl/ext/filesystem.go | 497 |
1 files changed, 0 insertions, 497 deletions
diff --git a/pkg/sentry/fsimpl/ext/filesystem.go b/pkg/sentry/fsimpl/ext/filesystem.go deleted file mode 100644 index 616fc002a..000000000 --- a/pkg/sentry/fsimpl/ext/filesystem.go +++ /dev/null @@ -1,497 +0,0 @@ -// 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 ext - -import ( - "errors" - "io" - "sync" - - "gvisor.dev/gvisor/pkg/abi/linux" - "gvisor.dev/gvisor/pkg/fspath" - "gvisor.dev/gvisor/pkg/sentry/context" - "gvisor.dev/gvisor/pkg/sentry/fsimpl/ext/disklayout" - "gvisor.dev/gvisor/pkg/sentry/vfs" - "gvisor.dev/gvisor/pkg/syserror" -) - -var ( - // errResolveDirent indicates that the vfs.ResolvingPath.Component() does - // not exist on the dentry tree but does exist on disk. So it has to be read in - // using the in-memory dirent and added to the dentry tree. Usually indicates - // the need to lock filesystem.mu for writing. - errResolveDirent = errors.New("resolve path component using dirent") -) - -// filesystem implements vfs.FilesystemImpl. -type filesystem struct { - vfsfs vfs.Filesystem - - // mu serializes changes to the Dentry tree. - mu sync.RWMutex - - // dev represents the underlying fs device. It does not require protection - // because io.ReaderAt permits concurrent read calls to it. It translates to - // the pread syscall which passes on the read request directly to the device - // driver. Device drivers are intelligent in serving multiple concurrent read - // requests in the optimal order (taking locality into consideration). - dev io.ReaderAt - - // inodeCache maps absolute inode numbers to the corresponding Inode struct. - // Inodes should be removed from this once their reference count hits 0. - // - // Protected by mu because most additions (see IterDirents) and all removals - // from this corresponds to a change in the dentry tree. - inodeCache map[uint32]*inode - - // sb represents the filesystem superblock. Immutable after initialization. - sb disklayout.SuperBlock - - // bgs represents all the block group descriptors for the filesystem. - // Immutable after initialization. - bgs []disklayout.BlockGroup -} - -// Compiles only if filesystem implements vfs.FilesystemImpl. -var _ vfs.FilesystemImpl = (*filesystem)(nil) - -// stepLocked resolves rp.Component() in parent directory vfsd. The write -// parameter passed tells if the caller has acquired filesystem.mu for writing -// or not. If set to true, an existing inode on disk can be added to the dentry -// tree if not present already. -// -// stepLocked is loosely analogous to fs/namei.c:walk_component(). -// -// Preconditions: -// - filesystem.mu must be locked (for writing if write param is true). -// - !rp.Done(). -// - inode == vfsd.Impl().(*Dentry).inode. -func stepLocked(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, inode *inode, write bool) (*vfs.Dentry, *inode, error) { - if !inode.isDir() { - return nil, nil, syserror.ENOTDIR - } - if err := inode.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil { - return nil, nil, err - } - - for { - nextVFSD, err := rp.ResolveComponent(vfsd) - if err != nil { - return nil, nil, err - } - if nextVFSD == nil { - // Since the Dentry tree is not the sole source of truth for extfs, if it's - // not in the Dentry tree, it might need to be pulled from disk. - childDirent, ok := inode.impl.(*directory).childMap[rp.Component()] - if !ok { - // The underlying inode does not exist on disk. - return nil, nil, syserror.ENOENT - } - - if !write { - // filesystem.mu must be held for writing to add to the dentry tree. - return nil, nil, errResolveDirent - } - - // Create and add the component's dirent to the dentry tree. - fs := rp.Mount().Filesystem().Impl().(*filesystem) - childInode, err := fs.getOrCreateInodeLocked(childDirent.diskDirent.Inode()) - if err != nil { - return nil, nil, err - } - // incRef because this is being added to the dentry tree. - childInode.incRef() - child := newDentry(childInode) - vfsd.InsertChild(&child.vfsd, rp.Component()) - - // Continue as usual now that nextVFSD is not nil. - nextVFSD = &child.vfsd - } - nextInode := nextVFSD.Impl().(*dentry).inode - if nextInode.isSymlink() && rp.ShouldFollowSymlink() { - if err := rp.HandleSymlink(inode.impl.(*symlink).target); err != nil { - return nil, nil, err - } - continue - } - rp.Advance() - return nextVFSD, nextInode, nil - } -} - -// walkLocked resolves rp to an existing file. The write parameter -// passed tells if the caller has acquired filesystem.mu for writing or not. -// If set to true, additions can be made to the dentry tree while walking. -// If errResolveDirent is returned, the walk needs to be continued with an -// upgraded filesystem.mu. -// -// walkLocked is loosely analogous to Linux's fs/namei.c:path_lookupat(). -// -// Preconditions: -// - filesystem.mu must be locked (for writing if write param is true). -func walkLocked(rp *vfs.ResolvingPath, write bool) (*vfs.Dentry, *inode, error) { - vfsd := rp.Start() - inode := vfsd.Impl().(*dentry).inode - for !rp.Done() { - var err error - vfsd, inode, err = stepLocked(rp, vfsd, inode, write) - if err != nil { - return nil, nil, err - } - } - if rp.MustBeDir() && !inode.isDir() { - return nil, nil, syserror.ENOTDIR - } - return vfsd, inode, nil -} - -// walkParentLocked resolves all but the last path component of rp to an -// existing directory. It does not check that the returned directory is -// searchable by the provider of rp. The write parameter passed tells if the -// caller has acquired filesystem.mu for writing or not. If set to true, -// additions can be made to the dentry tree while walking. -// If errResolveDirent is returned, the walk needs to be continued with an -// upgraded filesystem.mu. -// -// walkParentLocked is loosely analogous to Linux's fs/namei.c:path_parentat(). -// -// Preconditions: -// - filesystem.mu must be locked (for writing if write param is true). -// - !rp.Done(). -func walkParentLocked(rp *vfs.ResolvingPath, write bool) (*vfs.Dentry, *inode, error) { - vfsd := rp.Start() - inode := vfsd.Impl().(*dentry).inode - for !rp.Final() { - var err error - vfsd, inode, err = stepLocked(rp, vfsd, inode, write) - if err != nil { - return nil, nil, err - } - } - if !inode.isDir() { - return nil, nil, syserror.ENOTDIR - } - return vfsd, inode, nil -} - -// walk resolves rp to an existing file. If parent is set to true, it resolves -// the rp till the parent of the last component which should be an existing -// directory. If parent is false then resolves rp entirely. Attemps to resolve -// the path as far as it can with a read lock and upgrades the lock if needed. -func (fs *filesystem) walk(rp *vfs.ResolvingPath, parent bool) (*vfs.Dentry, *inode, error) { - var ( - vfsd *vfs.Dentry - inode *inode - err error - ) - - // Try walking with the hopes that all dentries have already been pulled out - // of disk. This reduces congestion (allows concurrent walks). - fs.mu.RLock() - if parent { - vfsd, inode, err = walkParentLocked(rp, false) - } else { - vfsd, inode, err = walkLocked(rp, false) - } - fs.mu.RUnlock() - - if err == errResolveDirent { - // Upgrade lock and continue walking. Lock upgrading in the middle of the - // walk is fine as this is a read only filesystem. - fs.mu.Lock() - if parent { - vfsd, inode, err = walkParentLocked(rp, true) - } else { - vfsd, inode, err = walkLocked(rp, true) - } - fs.mu.Unlock() - } - - return vfsd, inode, err -} - -// getOrCreateInodeLocked gets the inode corresponding to the inode number passed in. -// It creates a new one with the given inode number if one does not exist. -// The caller must increment the ref count if adding this to the dentry tree. -// -// Precondition: must be holding fs.mu for writing. -func (fs *filesystem) getOrCreateInodeLocked(inodeNum uint32) (*inode, error) { - if in, ok := fs.inodeCache[inodeNum]; ok { - return in, nil - } - - in, err := newInode(fs, inodeNum) - if err != nil { - return nil, err - } - - fs.inodeCache[inodeNum] = in - return in, nil -} - -// statTo writes the statfs fields to the output parameter. -func (fs *filesystem) statTo(stat *linux.Statfs) { - stat.Type = uint64(fs.sb.Magic()) - stat.BlockSize = int64(fs.sb.BlockSize()) - stat.Blocks = fs.sb.BlocksCount() - stat.BlocksFree = fs.sb.FreeBlocksCount() - stat.BlocksAvailable = fs.sb.FreeBlocksCount() - stat.Files = uint64(fs.sb.InodesCount()) - stat.FilesFree = uint64(fs.sb.FreeInodesCount()) - stat.NameLength = disklayout.MaxFileName - stat.FragmentSize = int64(fs.sb.BlockSize()) - // TODO(b/134676337): Set Statfs.Flags and Statfs.FSID. -} - -// GetDentryAt implements vfs.FilesystemImpl.GetDentryAt. -func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetDentryOptions) (*vfs.Dentry, error) { - vfsd, inode, err := fs.walk(rp, false) - if err != nil { - return nil, err - } - - if opts.CheckSearchable { - if !inode.isDir() { - return nil, syserror.ENOTDIR - } - if err := inode.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil { - return nil, err - } - } - - inode.incRef() - return vfsd, nil -} - -// GetParentDentryAt implements vfs.FilesystemImpl.GetParentDentryAt. -func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, error) { - vfsd, inode, err := fs.walk(rp, true) - if err != nil { - return nil, err - } - inode.incRef() - return vfsd, nil -} - -// OpenAt implements vfs.FilesystemImpl.OpenAt. -func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - vfsd, inode, err := fs.walk(rp, false) - if err != nil { - return nil, err - } - - // EROFS is returned if write access is needed. - if vfs.MayWriteFileWithOpenFlags(opts.Flags) || opts.Flags&(linux.O_CREAT|linux.O_EXCL|linux.O_TMPFILE) != 0 { - return nil, syserror.EROFS - } - return inode.open(rp, vfsd, opts.Flags) -} - -// ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt. -func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (string, error) { - _, inode, err := fs.walk(rp, false) - if err != nil { - return "", err - } - symlink, ok := inode.impl.(*symlink) - if !ok { - return "", syserror.EINVAL - } - return symlink.target, nil -} - -// StatAt implements vfs.FilesystemImpl.StatAt. -func (fs *filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.StatOptions) (linux.Statx, error) { - _, inode, err := fs.walk(rp, false) - if err != nil { - return linux.Statx{}, err - } - var stat linux.Statx - inode.statTo(&stat) - return stat, nil -} - -// StatFSAt implements vfs.FilesystemImpl.StatFSAt. -func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linux.Statfs, error) { - if _, _, err := fs.walk(rp, false); err != nil { - return linux.Statfs{}, err - } - - var stat linux.Statfs - fs.statTo(&stat) - return stat, nil -} - -// Release implements vfs.FilesystemImpl.Release. -func (fs *filesystem) Release() {} - -// Sync implements vfs.FilesystemImpl.Sync. -func (fs *filesystem) Sync(ctx context.Context) error { - // This is a readonly filesystem for now. - return nil -} - -// The vfs.FilesystemImpl functions below return EROFS because their respective -// man pages say that EROFS must be returned if the path resolves to a file on -// this read-only filesystem. - -// LinkAt implements vfs.FilesystemImpl.LinkAt. -func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error { - if rp.Done() { - return syserror.EEXIST - } - - if _, _, err := fs.walk(rp, true); err != nil { - return err - } - - return syserror.EROFS -} - -// MkdirAt implements vfs.FilesystemImpl.MkdirAt. -func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error { - if rp.Done() { - return syserror.EEXIST - } - - if _, _, err := fs.walk(rp, true); err != nil { - return err - } - - return syserror.EROFS -} - -// MknodAt implements vfs.FilesystemImpl.MknodAt. -func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error { - if rp.Done() { - return syserror.EEXIST - } - - _, _, err := fs.walk(rp, true) - if err != nil { - return err - } - - return syserror.EROFS -} - -// 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 rp.Done() { - return syserror.ENOENT - } - - _, _, err := fs.walk(rp, false) - if err != nil { - return err - } - - return syserror.EROFS -} - -// RmdirAt implements vfs.FilesystemImpl.RmdirAt. -func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error { - _, inode, err := fs.walk(rp, false) - if err != nil { - return err - } - - if !inode.isDir() { - return syserror.ENOTDIR - } - - return syserror.EROFS -} - -// SetStatAt implements vfs.FilesystemImpl.SetStatAt. -func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { - _, _, err := fs.walk(rp, false) - if err != nil { - return err - } - - return syserror.EROFS -} - -// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt. -func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error { - if rp.Done() { - return syserror.EEXIST - } - - _, _, err := fs.walk(rp, true) - if err != nil { - return err - } - - return syserror.EROFS -} - -// UnlinkAt implements vfs.FilesystemImpl.UnlinkAt. -func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error { - _, inode, err := fs.walk(rp, false) - if err != nil { - return err - } - - if inode.isDir() { - return syserror.EISDIR - } - - return syserror.EROFS -} - -// ListxattrAt implements vfs.FilesystemImpl.ListxattrAt. -func (fs *filesystem) ListxattrAt(ctx context.Context, rp *vfs.ResolvingPath) ([]string, error) { - _, _, err := fs.walk(rp, false) - if err != nil { - return nil, err - } - return nil, syserror.ENOTSUP -} - -// GetxattrAt implements vfs.FilesystemImpl.GetxattrAt. -func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) (string, error) { - _, _, err := fs.walk(rp, false) - 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 { - _, _, err := fs.walk(rp, false) - 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 { - _, _, err := fs.walk(rp, false) - 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.mu.RLock() - defer fs.mu.RUnlock() - return vfs.GenericPrependPath(vfsroot, vd, b) -} |