diff options
Diffstat (limited to 'pkg/sentry/fsimpl/gofer')
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/BUILD | 5 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/directory.go | 27 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/filesystem.go | 416 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/gofer.go | 794 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/gofer_test.go | 12 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/handle.go | 14 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/host_named_pipe.go | 97 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/regular_file.go | 321 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/socket.go | 6 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/special_file.go | 183 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/time.go | 18 |
11 files changed, 1372 insertions, 521 deletions
diff --git a/pkg/sentry/fsimpl/gofer/BUILD b/pkg/sentry/fsimpl/gofer/BUILD index 67e916525..16787116f 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", ], ) @@ -81,5 +85,6 @@ go_test( deps = [ "//pkg/p9", "//pkg/sentry/contexttest", + "//pkg/sentry/pgalloc", ], ) diff --git a/pkg/sentry/fsimpl/gofer/directory.go b/pkg/sentry/fsimpl/gofer/directory.go index b98218753..2a8011eb4 100644 --- a/pkg/sentry/fsimpl/gofer/directory.go +++ b/pkg/sentry/fsimpl/gofer/directory.go @@ -85,14 +85,13 @@ 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), blockSize: usermem.PageSize, // arbitrary - handle: handle{ - fd: -1, - }, - nlink: uint32(2), + hostFD: -1, + nlink: uint32(2), } switch opts.mode.FileType() { case linux.S_IFDIR: @@ -121,7 +120,7 @@ type directoryFD struct { } // Release implements vfs.FileDescriptionImpl.Release. -func (fd *directoryFD) Release() { +func (fd *directoryFD) Release(context.Context) { } // IterDirents implements vfs.FileDescriptionImpl.IterDirents. @@ -138,6 +137,7 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba fd.dirents = ds } + d.InotifyWithParent(ctx, linux.IN_ACCESS, 0, vfs.PathEvent) if d.cachedMetadataAuthoritative() { d.touchAtime(fd.vfsfd.Mount()) } @@ -183,13 +183,13 @@ 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, }, } @@ -203,14 +203,14 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) { off := uint64(0) const count = 64 * 1024 // for consistency with the vfs1 client d.handleMu.RLock() - if !d.handleReadable { + if d.readFile.isNil() { // This should not be possible because a readable handle should // have been opened when the calling directoryFD was opened. d.handleMu.RUnlock() panic("gofer.dentry.getDirents called without a readable handle") } for { - p9ds, err := d.handle.file.readdir(ctx, off, count) + p9ds, err := d.readFile.readdir(ctx, off, count) if err != nil { d.handleMu.RUnlock() return nil, err @@ -225,7 +225,7 @@ 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 +258,7 @@ 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 +299,8 @@ 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().syncRemoteFile(ctx) +} diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index 7f2181216..40fec890a 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -15,7 +15,9 @@ package gofer import ( + "math" "sync" + "sync/atomic" "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" @@ -53,8 +55,8 @@ func (fs *filesystem) Sync(ctx context.Context) error { // Sync regular files. for _, d := range ds { - err := d.syncSharedHandle(ctx) - d.DecRef() + err := d.syncCachedFile(ctx) + d.DecRef(ctx) if err != nil && retErr == nil { retErr = err } @@ -64,7 +66,7 @@ func (fs *filesystem) Sync(ctx context.Context) error { // handles (so they won't be synced by the above). for _, sffd := range sffds { err := sffd.Sync(ctx) - sffd.vfsfd.DecRef() + sffd.vfsfd.DecRef(ctx) if err != nil && retErr == nil { retErr = err } @@ -118,7 +120,7 @@ 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 } @@ -132,7 +134,7 @@ afterSymlink: return d, nil } if name == ".." { - if isRoot, err := rp.CheckRoot(&d.vfsd); err != nil { + if isRoot, err := rp.CheckRoot(ctx, &d.vfsd); err != nil { return nil, err } else if isRoot || d.parent == nil { rp.Advance() @@ -145,15 +147,13 @@ afterSymlink: // // Call rp.CheckMount() before updating d.parent's metadata, since if // we traverse to another mount then d.parent's metadata is irrelevant. - if err := rp.CheckMount(&d.parent.vfsd); err != nil { + if err := rp.CheckMount(ctx, &d.parent.vfsd); err != nil { 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 @@ -165,10 +165,10 @@ afterSymlink: if child == nil { return nil, syserror.ENOENT } - if err := rp.CheckMount(&child.vfsd); err != nil { + if err := rp.CheckMount(ctx, &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 +208,28 @@ 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. @@ -230,7 +240,7 @@ func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir // has 0 references, drop it). Wait to update parent.children until we // know what to replace the existing dentry with (i.e. one of the // returns below), to avoid a redundant map access. - vfsObj.InvalidateDentry(&child.vfsd) + vfsObj.InvalidateDentry(ctx, &child.vfsd) if child.isSynthetic() { // Normally we don't mark invalidated dentries as deleted since // they may still exist (but at a different path), and also for @@ -275,7 +285,7 @@ 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 +311,7 @@ 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 @@ -323,7 +333,7 @@ func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath, func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool, createInRemoteDir func(parent *dentry, name string) error, createInSyntheticDir func(parent *dentry, name string) error) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) start := rp.Start().Impl().(*dentry) if !start.cachedMetadataAuthoritative() { // Get updated metadata for start as required by @@ -371,17 +381,33 @@ 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(ctx, 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(ctx, name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */) + return nil } if child := parent.children[name]; child != nil { return syserror.EEXIST @@ -397,6 +423,11 @@ 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(ctx, name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */) return nil } @@ -404,7 +435,7 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool) error { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) start := rp.Start().Impl().(*dentry) if !start.cachedMetadataAuthoritative() { // Get updated metadata for start as required by @@ -440,24 +471,64 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b } vfsObj := rp.VirtualFilesystem() mntns := vfs.MountNamespaceFromContext(ctx) - defer mntns.DecRef() + defer mntns.DecRef(ctx) 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 +589,7 @@ 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 { @@ -527,8 +598,20 @@ 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(ctx, 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(ctx, cw, &parent.watches, name) + } + if child != nil { - vfsObj.CommitDeleteDentry(&child.vfsd) + vfsObj.CommitDeleteDentry(ctx, &child.vfsd) child.setDeleted() if child.isSynthetic() { parent.syntheticChildren-- @@ -555,7 +638,7 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b // but dentry slices are allocated lazily, and it's much easier to say "defer // fs.renameMuRUnlockAndCheckCaching(&ds)" than "defer func() { // fs.renameMuRUnlockAndCheckCaching(ds) }()" to work around this. -func (fs *filesystem) renameMuRUnlockAndCheckCaching(ds **[]*dentry) { +func (fs *filesystem) renameMuRUnlockAndCheckCaching(ctx context.Context, ds **[]*dentry) { fs.renameMu.RUnlock() if *ds == nil { return @@ -563,20 +646,20 @@ func (fs *filesystem) renameMuRUnlockAndCheckCaching(ds **[]*dentry) { if len(**ds) != 0 { fs.renameMu.Lock() for _, d := range **ds { - d.checkCachingLocked() + d.checkCachingLocked(ctx) } fs.renameMu.Unlock() } putDentrySlice(*ds) } -func (fs *filesystem) renameMuUnlockAndCheckCaching(ds **[]*dentry) { +func (fs *filesystem) renameMuUnlockAndCheckCaching(ctx context.Context, ds **[]*dentry) { if *ds == nil { fs.renameMu.Unlock() return } for _, d := range **ds { - d.checkCachingLocked() + d.checkCachingLocked(ctx) } fs.renameMu.Unlock() putDentrySlice(*ds) @@ -586,7 +669,7 @@ func (fs *filesystem) renameMuUnlockAndCheckCaching(ds **[]*dentry) { 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.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return err @@ -598,7 +681,7 @@ func (fs *filesystem) AccessAt(ctx context.Context, rp *vfs.ResolvingPath, creds func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetDentryOptions) (*vfs.Dentry, error) { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return nil, err @@ -619,7 +702,7 @@ func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, op func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, error) { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) start := rp.Start().Impl().(*dentry) if !start.cachedMetadataAuthoritative() { // Get updated metadata for start as required by @@ -642,8 +725,29 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs. if rp.Mount() != vd.Mount() { return syserror.EXDEV } - // 9P2000.L supports hard links, but we don't. - return syserror.EPERM + d := vd.Dentry().Impl().(*dentry) + if d.isDir() { + return syserror.EPERM + } + gid := auth.KGID(atomic.LoadUint32(&d.gid)) + uid := auth.KUID(atomic.LoadUint32(&d.uid)) + mode := linux.FileMode(atomic.LoadUint32(&d.mode)) + if err := vfs.MayLink(rp.Credentials(), mode, uid, gid); err != nil { + return err + } + if d.nlink == 0 { + return syserror.ENOENT + } + if d.nlink == math.MaxUint32 { + return syserror.EMLINK + } + if err := parent.file.link(ctx, d.file, childName); err != nil { + return err + } + + // Success! + atomic.AddUint32(&d.nlink, 1) + return nil }, nil) } @@ -730,7 +834,7 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) start := rp.Start().Impl().(*dentry) if !start.cachedMetadataAuthoritative() { @@ -740,6 +844,13 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf } } if rp.Done() { + // Reject attempts to open mount root directory with O_CREAT. + if mayCreate && rp.MustBeDir() { + return nil, syserror.EISDIR + } + if mustCreate { + return nil, syserror.EEXIST + } return start.openLocked(ctx, rp, &opts) } @@ -752,27 +863,33 @@ afterTrailingSymlink: if err := parent.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil { return nil, err } + // Reject attempts to open directories with O_CREAT. + if mayCreate && rp.MustBeDir() { + return nil, syserror.EISDIR + } // 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 +910,32 @@ 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 +955,7 @@ 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 +972,28 @@ 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 } } - return d.openSpecialFileLocked(ctx, mnt, opts) + + 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 vfd, err } func (d *dentry) connectSocketLocked(ctx context.Context, opts *vfs.OpenOptions) (*vfs.FileDescription, error) { @@ -873,19 +1021,37 @@ 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 +1060,7 @@ 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 +1085,7 @@ 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) @@ -947,22 +1113,25 @@ 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 { child.handleMu.Lock() - child.handle.file = openFile - if fdobj != nil { - child.handle.fd = int32(fdobj.Release()) + if vfs.MayReadFileWithOpenFlags(opts.Flags) { + child.readFile = openFile + if fdobj != nil { + child.hostFD = int32(fdobj.Release()) + } + } else if fdobj != nil { + // Can't use fdobj if it's not readable. + fdobj.Close() + } + if vfs.MayWriteFileWithOpenFlags(opts.Flags) { + child.writeFile = openFile } - child.handleReadable = vfs.MayReadFileWithOpenFlags(opts.Flags) - 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 +1143,7 @@ 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 +1151,21 @@ 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(ctx, name, linux.IN_CREATE, 0, vfs.PathEvent, false /* unlinked */) return childVFSFD, nil } @@ -1008,7 +1173,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (string, error) { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return "", err @@ -1028,7 +1193,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa var ds *[]*dentry fs.renameMu.Lock() - defer fs.renameMuUnlockAndCheckCaching(&ds) + defer fs.renameMuUnlockAndCheckCaching(ctx, &ds) newParent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*dentry), &ds) if err != nil { return err @@ -1052,7 +1217,8 @@ 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 +1233,15 @@ 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 +1252,7 @@ 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() @@ -1114,7 +1283,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa return nil } mntns := vfs.MountNamespaceFromContext(ctx) - defer mntns.DecRef() + defer mntns.DecRef(ctx) if err := vfsObj.PrepareRenameDentry(mntns, &renamed.vfsd, replacedVFSD); err != nil { return err } @@ -1139,7 +1308,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa } // Update the dentry tree. - vfsObj.CommitRenameReplaceDentry(&renamed.vfsd, replacedVFSD) + vfsObj.CommitRenameReplaceDentry(ctx, &renamed.vfsd, replacedVFSD) if replaced != nil { replaced.setDeleted() if replaced.isSynthetic() { @@ -1181,10 +1350,12 @@ 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 } @@ -1197,19 +1368,28 @@ 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(ctx, &ds) + return err + } + if err := d.setStat(ctx, rp.Credentials(), &opts, rp.Mount()); err != nil { + fs.renameMuRUnlockAndCheckCaching(ctx, &ds) return err } - return d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount()) + fs.renameMuRUnlockAndCheckCaching(ctx, &ds) + + if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 { + d.InotifyWithParent(ctx, ev, 0, vfs.InodeEvent) + } + 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.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return linux.Statx{}, err @@ -1226,7 +1406,7 @@ func (fs *filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linux.Statfs, error) { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return linux.Statfs{}, err @@ -1276,7 +1456,7 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error func (fs *filesystem) BoundEndpointAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.BoundEndpointOptions) (transport.BoundEndpoint, error) { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return nil, err @@ -1302,7 +1482,7 @@ func (fs *filesystem) BoundEndpointAt(ctx context.Context, rp *vfs.ResolvingPath func (fs *filesystem) ListxattrAt(ctx context.Context, rp *vfs.ResolvingPath, size uint64) ([]string, error) { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return nil, err @@ -1314,7 +1494,7 @@ func (fs *filesystem) ListxattrAt(ctx context.Context, rp *vfs.ResolvingPath, si func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetxattrOptions) (string, error) { var ds *[]*dentry fs.renameMu.RLock() - defer fs.renameMuRUnlockAndCheckCaching(&ds) + defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds) d, err := fs.resolveLocked(ctx, rp, &ds) if err != nil { return "", err @@ -1326,24 +1506,38 @@ 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(ctx, &ds) return err } - return d.setxattr(ctx, rp.Credentials(), &opts) + if err := d.setxattr(ctx, rp.Credentials(), &opts); err != nil { + fs.renameMuRUnlockAndCheckCaching(ctx, &ds) + return err + } + fs.renameMuRUnlockAndCheckCaching(ctx, &ds) + + d.InotifyWithParent(ctx, 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(ctx, &ds) return err } - return d.removexattr(ctx, rp.Credentials(), name) + if err := d.removexattr(ctx, rp.Credentials(), name); err != nil { + fs.renameMuRUnlockAndCheckCaching(ctx, &ds) + return err + } + fs.renameMuRUnlockAndCheckCaching(ctx, &ds) + + d.InotifyWithParent(ctx, linux.IN_ATTRIB, 0, vfs.InodeEvent) + return nil } // PrependPath implements vfs.FilesystemImpl.PrependPath. @@ -1352,3 +1546,7 @@ 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..63e589859 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 @@ -175,10 +192,14 @@ const ( // // - File timestamps are based on client clocks. This ensures that users of // the client observe timestamps that are coherent with their own clocks - // and consistent with Linux's semantics. However, since it is not always - // possible for clients to set arbitrary atimes and mtimes, and never - // possible for clients to set arbitrary ctimes, file timestamp changes are - // stored in the client only and never sent to the remote filesystem. + // and consistent with Linux's semantics (in particular, it is not always + // possible for clients to set arbitrary atimes and mtimes depending on the + // remote filesystem implementation, and never possible for clients to set + // arbitrary ctimes.) If a dentry containing a client-defined atime or + // mtime is evicted from cache, client timestamps will be sent to the + // remote filesystem on a best-effort basis to attempt to ensure that + // timestamps will be preserved when another dentry representing the same + // file is instantiated. InteropModeExclusive InteropMode = iota // InteropModeWritethrough is appropriate when there are read-only users of @@ -230,6 +251,15 @@ 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 +345,31 @@ 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 +477,6 @@ 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{}), } @@ -433,7 +486,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt root, err := fs.newDentry(ctx, attachFile, qid, attrMask, &attr) if err != nil { attachFile.close(ctx) - fs.vfsfs.DecRef() + fs.vfsfs.DecRef(ctx) return nil, nil, err } // Set the root's reference count to 2. One reference is returned to the @@ -446,17 +499,16 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt } // Release implements vfs.FilesystemImpl.Release. -func (fs *filesystem) Release() { - ctx := context.Background() +func (fs *filesystem) Release(ctx context.Context) { mf := fs.mfp.MemoryFile() fs.syncMu.Lock() for d := range fs.syncableDentries { d.handleMu.Lock() d.dataMu.Lock() - if d.handleWritable { + if h := d.writeHandleLocked(); h.isOpen() { // Write dirty cached data to the remote file. - if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, fs.mfp.MemoryFile(), d.handle.writeFromBlocksAt); err != nil { + if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, fs.mfp.MemoryFile(), h.writeFromBlocksAt); err != nil { log.Warningf("gofer.filesystem.Release: failed to flush dentry: %v", err) } // TODO(jamieliu): Do we need to flushf/fsync d? @@ -466,9 +518,9 @@ func (fs *filesystem) Release() { d.dirty.RemoveAll() d.dataMu.Unlock() // Close the host fd if one exists. - if d.handle.fd >= 0 { - syscall.Close(int(d.handle.fd)) - d.handle.fd = -1 + if d.hostFD >= 0 { + syscall.Close(int(d.hostFD)) + d.hostFD = -1 } d.handleMu.Unlock() } @@ -510,8 +562,6 @@ type dentry struct { // filesystem.renameMu. name string - // We don't support hard links, so each dentry maps 1:1 to an inode. - // file is the unopened p9.File that backs this dentry. file is immutable. // // If file.isNil(), this dentry represents a synthetic file, i.e. a file @@ -553,22 +603,39 @@ 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). + // File size, which differs from other metadata in two ways: + // + // - We make a best-effort attempt to keep it up to date even if + // !dentry.cachedMetadataAuthoritative() for the sake of O_APPEND writes. + // + // - size is protected by both metadataMu and dataMu (i.e. both must be + // locked to mutate it; locking either is sufficient to access it). size uint64 + // If this dentry does not represent a synthetic file, deleted is 0, and + // atimeDirty/mtimeDirty are non-zero, atime/mtime may have diverged from the + // remote file's timestamps, which should be updated when this dentry is + // evicted. + atimeDirty uint32 + mtimeDirty uint32 // nlink counts the number of hard links to this dentry. It's updated and // accessed using atomic operations. It's not protected by metadataMu like the @@ -581,30 +648,28 @@ type dentry struct { // the file into memmap.MappingSpaces. mappings is protected by mapsMu. mappings memmap.MappingSet - // If this dentry represents a regular file or directory: - // - // - handle is the I/O handle used by all regularFileFDs/directoryFDs - // representing this dentry. - // - // - handleReadable is true if handle is readable. - // - // - handleWritable is true if handle is writable. - // - // Invariants: + // - If this dentry represents a regular file or directory, readFile is the + // p9.File used for reads by all regularFileFDs/directoryFDs representing + // this dentry. // - // - If handleReadable == handleWritable == false, then handle.file == nil - // (i.e. there is no open handle). Conversely, if handleReadable || - // handleWritable == true, then handle.file != nil (i.e. there is an open - // handle). + // - If this dentry represents a regular file, writeFile is the p9.File + // used for writes by all regularFileFDs representing this dentry. // - // - handleReadable and handleWritable cannot transition from true to false - // (i.e. handles may not be downgraded). + // - If this dentry represents a regular file, hostFD is the host FD used + // for memory mappings and I/O (when applicable) in preference to readFile + // and writeFile. hostFD is always readable; if !writeFile.isNil(), it must + // also be writable. If hostFD is -1, no such host FD is available. // // These fields are protected by handleMu. - handleMu sync.RWMutex - handle handle - handleReadable bool - handleWritable bool + // + // readFile and writeFile may or may not represent the same p9.File. Once + // either p9.File transitions from closed (isNil() == true) to open + // (isNil() == false), it may be mutated with handleMu locked, but cannot + // be closed until the dentry is destroyed. + handleMu sync.RWMutex + readFile p9file + writeFile p9file + hostFD int32 dataMu sync.RWMutex @@ -618,7 +683,7 @@ type dentry struct { // tracks dirty segments in cache. dirty is protected by dataMu. dirty fsutil.DirtySet - // pf implements platform.File for mappings of handle.fd. + // pf implements platform.File for mappings of hostFD. pf dentryPlatformFile // If this dentry represents a symbolic link, InteropModeShared is not in @@ -634,6 +699,11 @@ 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 @@ -670,14 +740,12 @@ 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, - }, + hostFD: -1, } d.pf.dentry = d if mask.UID { @@ -725,8 +793,8 @@ 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() @@ -744,10 +812,12 @@ func (d *dentry) updateFromP9Attrs(mask p9.AttrMask, attr *p9.Attr) { if attr.BlockSize != 0 { atomic.StoreUint32(&d.blockSize, uint32(attr.BlockSize)) } - if mask.ATime { + // Don't override newer client-defined timestamps with old server-defined + // ones. + if mask.ATime && atomic.LoadUint32(&d.atimeDirty) == 0 { atomic.StoreInt64(&d.atime, dentryTimestampFromP9(attr.ATimeSeconds, attr.ATimeNanoSeconds)) } - if mask.MTime { + if mask.MTime && atomic.LoadUint32(&d.mtimeDirty) == 0 { atomic.StoreInt64(&d.mtime, dentryTimestampFromP9(attr.MTimeSeconds, attr.MTimeNanoSeconds)) } if mask.CTime { @@ -760,25 +830,33 @@ 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() func (d *dentry) updateFromGetattr(ctx context.Context) error { - // Use d.handle.file, which represents a 9P fid that has been opened, in - // preference to d.file, which represents a 9P fid that has not. This may - // be significantly more efficient in some implementations. + // Use d.readFile or d.writeFile, which represent 9P fids that have been + // opened, in preference to d.file, which represents a 9P fid that has not. + // This may be significantly more efficient in some implementations. Prefer + // d.writeFile over d.readFile since some filesystem implementations may + // update a writable handle's metadata after writes to that handle, without + // making metadata updates immediately visible to read-only handles + // representing the same file. var ( 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 + if !d.writeFile.isNil() { + file = d.writeFile + handleMuRLocked = true + } else if !d.readFile.isNil() { + file = d.readFile handleMuRLocked = true } else { file = d.file @@ -791,7 +869,7 @@ 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 +881,18 @@ 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 +905,8 @@ 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 } @@ -827,37 +914,47 @@ 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 { return err } defer mnt.EndWrite() - setLocalAtime := false - setLocalMtime := false + + if stat.Mask&linux.STATX_SIZE != 0 { + // Reject attempts to truncate files other than regular files, since + // filesystem implementations may return the wrong errno. + switch mode.FileType() { + case linux.S_IFREG: + // ok + case linux.S_IFDIR: + return syserror.EISDIR + default: + return syserror.EINVAL + } + } + + var now int64 if d.cachedMetadataAuthoritative() { - // Timestamp updates will be handled locally. - setLocalAtime = stat.Mask&linux.STATX_ATIME != 0 - setLocalMtime = stat.Mask&linux.STATX_MTIME != 0 - stat.Mask &^= linux.STATX_ATIME | linux.STATX_MTIME - - // Prepare for truncate. - if stat.Mask&linux.STATX_SIZE != 0 { - switch d.mode & linux.S_IFMT { - case linux.S_IFREG: - if !setLocalMtime { - // Truncate updates mtime. - setLocalMtime = true - stat.Mtime.Nsec = linux.UTIME_NOW - } - case linux.S_IFDIR: - return syserror.EISDIR - default: - return syserror.EINVAL + // Truncate updates mtime. + if stat.Mask&(linux.STATX_SIZE|linux.STATX_MTIME) == linux.STATX_SIZE { + stat.Mask |= linux.STATX_MTIME + stat.Mtime = linux.StatxTimestamp{ + Nsec: linux.UTIME_NOW, } } + + // Use client clocks for timestamps. + now = d.fs.clock.Now().Nanoseconds() + if stat.Mask&linux.STATX_ATIME != 0 && stat.Atime.Nsec == linux.UTIME_NOW { + stat.Atime = statxTimestampFromDentry(now) + } + if stat.Mask&linux.STATX_MTIME != 0 && stat.Mtime.Nsec == linux.UTIME_NOW { + stat.Mtime = statxTimestampFromDentry(now) + } } + d.metadataMu.Lock() defer d.metadataMu.Unlock() if !d.isSynthetic() { @@ -883,6 +980,12 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin }); err != nil { return err } + if stat.Mask&linux.STATX_SIZE != 0 { + // d.size should be kept up to date, and privatized + // copy-on-write mappings of truncated pages need to be + // invalidated, even if InteropModeShared is in effect. + d.updateFileSizeLocked(stat.Size) + } } if d.fs.opts.interop == InteropModeShared { // There's no point to updating d's metadata in this case since @@ -892,7 +995,6 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin return nil } } - now := d.fs.clock.Now().Nanoseconds() if stat.Mask&linux.STATX_MODE != 0 { atomic.StoreUint32(&d.mode, d.fileType()|uint32(stat.Mode)) } @@ -902,61 +1004,66 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin if stat.Mask&linux.STATX_GID != 0 { atomic.StoreUint32(&d.gid, stat.GID) } - if setLocalAtime { - if stat.Atime.Nsec == linux.UTIME_NOW { - atomic.StoreInt64(&d.atime, now) - } else { - atomic.StoreInt64(&d.atime, dentryTimestampFromStatx(stat.Atime)) - } + // Note that stat.Atime.Nsec and stat.Mtime.Nsec can't be UTIME_NOW because + // if d.cachedMetadataAuthoritative() then we converted stat.Atime and + // stat.Mtime to client-local timestamps above, and if + // !d.cachedMetadataAuthoritative() then we returned after calling + // d.file.setAttr(). For the same reason, now must have been initialized. + if stat.Mask&linux.STATX_ATIME != 0 { + atomic.StoreInt64(&d.atime, dentryTimestampFromStatx(stat.Atime)) + atomic.StoreUint32(&d.atimeDirty, 0) } - if setLocalMtime { - if stat.Mtime.Nsec == linux.UTIME_NOW { - atomic.StoreInt64(&d.mtime, now) - } else { - atomic.StoreInt64(&d.mtime, dentryTimestampFromStatx(stat.Mtime)) - } + if stat.Mask&linux.STATX_MTIME != 0 { + atomic.StoreInt64(&d.mtime, dentryTimestampFromStatx(stat.Mtime)) + atomic.StoreUint32(&d.mtimeDirty, 0) } 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) @@ -992,10 +1099,10 @@ func (d *dentry) TryIncRef() bool { } // DecRef implements vfs.DentryImpl.DecRef. -func (d *dentry) DecRef() { +func (d *dentry) DecRef(ctx context.Context) { if refs := atomic.AddInt64(&d.refs, -1); refs == 0 { d.fs.renameMu.Lock() - d.checkCachingLocked() + d.checkCachingLocked(ctx) d.fs.renameMu.Unlock() } else if refs < 0 { panic("gofer.dentry.DecRef() called without holding a reference") @@ -1011,6 +1118,37 @@ func (d *dentry) decRefLocked() { } } +// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. +func (d *dentry) InotifyWithParent(ctx context.Context, 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(ctx, d.name, events, cookie, et, d.isDeleted()) + } + d.watches.Notify(ctx, "", 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(ctx context.Context) { + if atomic.LoadInt64(&d.refs) == 0 { + d.fs.renameMu.Lock() + d.checkCachingLocked(ctx) + d.fs.renameMu.Unlock() + } +} + // checkCachingLocked should be called after d's reference count becomes 0 or it // becomes disowned. // @@ -1020,8 +1158,9 @@ func (d *dentry) decRefLocked() { // operation. One of the calls may destroy the dentry, so subsequent calls will // do nothing. // -// Preconditions: d.fs.renameMu must be locked for writing. -func (d *dentry) checkCachingLocked() { +// Preconditions: d.fs.renameMu must be locked for writing; it may be +// temporarily unlocked. +func (d *dentry) checkCachingLocked(ctx context.Context) { // Dentries with a non-zero 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 @@ -1042,12 +1181,23 @@ 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(ctx) + } if d.cached { d.fs.cachedDentries.Remove(d) d.fs.cachedDentriesLen-- d.cached = false } - d.destroyLocked() + d.destroyLocked(ctx) + 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. @@ -1074,7 +1224,7 @@ func (d *dentry) checkCachingLocked() { if !victim.vfsd.IsDead() { // Note that victim can't be a mount point (in any mount // namespace), since VFS holds references on mount points. - d.fs.vfsfs.VirtualFilesystem().InvalidateDentry(&victim.vfsd) + d.fs.vfsfs.VirtualFilesystem().InvalidateDentry(ctx, &victim.vfsd) delete(victim.parent.children, victim.name) // We're only deleting the dentry, not the file it // represents, so we don't need to update @@ -1082,19 +1232,21 @@ func (d *dentry) checkCachingLocked() { } victim.parent.dirMu.Unlock() } - victim.destroyLocked() + victim.destroyLocked(ctx) } // Whether or not victim was destroyed, we brought fs.cachedDentriesLen // back down to fs.opts.maxCachedDentries, so we don't loop. } } -// destroyLocked destroys the dentry. It may flushes dirty pages from cache, -// close p9 file and remove reference on parent dentry. +// destroyLocked destroys the dentry. // -// Preconditions: d.fs.renameMu must be locked for writing. d.refs == 0. d is -// not a child dentry. -func (d *dentry) destroyLocked() { +// Preconditions: +// * d.fs.renameMu must be locked for writing; it may be temporarily unlocked. +// * d.refs == 0. +// * d.parent.children[d.name] != d, i.e. d is not reachable by path traversal +// from its former parent dentry. +func (d *dentry) destroyLocked(ctx context.Context) { switch atomic.LoadInt64(&d.refs) { case 0: // Mark the dentry destroyed. @@ -1105,27 +1257,64 @@ func (d *dentry) destroyLocked() { panic("dentry.destroyLocked() called with references on the dentry") } - ctx := context.Background() + // Allow the following to proceed without renameMu locked to improve + // scalability. + d.fs.renameMu.Unlock() + + mf := d.fs.mfp.MemoryFile() d.handleMu.Lock() - if !d.handle.file.isNil() { - mf := d.fs.mfp.MemoryFile() - d.dataMu.Lock() + d.dataMu.Lock() + if h := d.writeHandleLocked(); h.isOpen() { // Write dirty pages back to the remote filesystem. - if d.handleWritable { - if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, mf, d.handle.writeFromBlocksAt); err != nil { - log.Warningf("gofer.dentry.DecRef: failed to write dirty data back: %v", err) - } + if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, mf, h.writeFromBlocksAt); err != nil { + log.Warningf("gofer.dentry.destroyLocked: failed to write dirty data back: %v", err) } - // Discard cached data. + } + // Discard cached data. + if !d.cache.IsEmpty() { + mf.MarkAllUnevictable(d) d.cache.DropAll(mf) d.dirty.RemoveAll() - d.dataMu.Unlock() - // Clunk open fids and close open host FDs. - d.handle.close(ctx) + } + d.dataMu.Unlock() + // Clunk open fids and close open host FDs. + if !d.readFile.isNil() { + d.readFile.close(ctx) + } + if !d.writeFile.isNil() && d.readFile != d.writeFile { + d.writeFile.close(ctx) + } + d.readFile = p9file{} + d.writeFile = p9file{} + if d.hostFD >= 0 { + syscall.Close(int(d.hostFD)) + d.hostFD = -1 } d.handleMu.Unlock() if !d.file.isNil() { + if !d.isDeleted() { + // Write dirty timestamps back to the remote filesystem. + atimeDirty := atomic.LoadUint32(&d.atimeDirty) != 0 + mtimeDirty := atomic.LoadUint32(&d.mtimeDirty) != 0 + if atimeDirty || mtimeDirty { + atime := atomic.LoadInt64(&d.atime) + mtime := atomic.LoadInt64(&d.mtime) + if err := d.file.setAttr(ctx, p9.SetAttrMask{ + ATime: atimeDirty, + ATimeNotSystemTime: atimeDirty, + MTime: mtimeDirty, + MTimeNotSystemTime: mtimeDirty, + }, p9.SetAttr{ + ATimeSeconds: uint64(atime / 1e9), + ATimeNanoSeconds: uint64(atime % 1e9), + MTimeSeconds: uint64(mtime / 1e9), + MTimeNanoSeconds: uint64(mtime % 1e9), + }); err != nil { + log.Warningf("gofer.dentry.destroyLocked: failed to write dirty timestamps back: %v", err) + } + } + } d.file.close(ctx) d.file = p9file{} // Remove d from the set of syncable dentries. @@ -1133,11 +1322,14 @@ func (d *dentry) destroyLocked() { delete(d.fs.syncableDentries, d) d.fs.syncMu.Unlock() } + + d.fs.renameMu.Lock() + // Drop the reference held by d on its parent without recursively locking // d.fs.renameMu. if d.parent != nil { if refs := atomic.AddInt64(&d.parent.refs, -1); refs == 0 { - d.parent.checkCachingLocked() + d.parent.checkCachingLocked(ctx) } else if refs < 0 { panic("gofer.dentry.DecRef() called without holding a reference") } @@ -1155,7 +1347,7 @@ 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 +1373,9 @@ 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 +1389,9 @@ 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) } @@ -1207,89 +1405,139 @@ 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). if !trunc { d.handleMu.RLock() - if (!read || d.handleReadable) && (!write || d.handleWritable) { - // The current handle is sufficient. + if (!read || !d.readFile.isNil()) && (!write || !d.writeFile.isNil()) { + // Current handles are sufficient. d.handleMu.RUnlock() return nil } d.handleMu.RUnlock() } - haveOldFD := false + fdToClose := int32(-1) + invalidateTranslations := false d.handleMu.Lock() - if (read && !d.handleReadable) || (write && !d.handleWritable) || trunc { - // Get a new handle. - wantReadable := d.handleReadable || read - wantWritable := d.handleWritable || write - h, err := openHandle(ctx, d.file, wantReadable, wantWritable, trunc) + if (read && d.readFile.isNil()) || (write && d.writeFile.isNil()) || trunc { + // Get a new handle. If this file has been opened for both reading and + // writing, try to get a single handle that is usable for both: + // + // - Writable memory mappings of a host FD require that the host FD is + // opened for both reading and writing. + // + // - NOTE(b/141991141): Some filesystems may not ensure coherence + // between multiple handles for the same file. + openReadable := !d.readFile.isNil() || read + openWritable := !d.writeFile.isNil() || write + h, err := openHandle(ctx, d.file, openReadable, openWritable, trunc) + if err == syserror.EACCES && (openReadable != read || openWritable != write) { + // It may not be possible to use a single handle for both + // reading and writing, since permissions on the file may have + // changed to e.g. disallow reading after previously being + // opened for reading. In this case, we have no choice but to + // use separate handles for reading and writing. + ctx.Debugf("gofer.dentry.ensureSharedHandle: bifurcating read/write handles for dentry %p", d) + openReadable = read + openWritable = write + h, err = openHandle(ctx, d.file, openReadable, openWritable, trunc) + } if err != nil { d.handleMu.Unlock() return err } - if !d.handle.file.isNil() { - // Check that old and new handles are compatible: If the old handle - // includes a host file descriptor but the new one does not, or - // vice versa, old and new memory mappings may be incoherent. - haveOldFD = d.handle.fd >= 0 - haveNewFD := h.fd >= 0 - if haveOldFD != haveNewFD { - d.handleMu.Unlock() - ctx.Warningf("gofer.dentry.ensureSharedHandle: can't change host FD availability from %v to %v across dentry handle upgrade", haveOldFD, haveNewFD) - h.close(ctx) - return syserror.EIO - } - if haveOldFD { - // We may have raced with callers of d.pf.FD() that are now - // using the old file descriptor, preventing us from safely - // closing it. We could handle this by invalidating existing - // memmap.Translations, but this is expensive. Instead, use - // dup3 to make the old file descriptor refer to the new file - // description, then close the new file descriptor (which is no - // longer needed). Racing callers may use the old or new file - // description, but this doesn't matter since they refer to the - // same file (unless d.fs.opts.overlayfsStaleRead is true, - // which we handle separately). - if err := syscall.Dup3(int(h.fd), int(d.handle.fd), syscall.O_CLOEXEC); err != nil { + + if d.hostFD < 0 && openReadable && h.fd >= 0 { + // We have no existing FD; use the new FD for at least reading. + d.hostFD = h.fd + } else if d.hostFD >= 0 && d.writeFile.isNil() && openWritable { + // We have an existing read-only FD, but the file has just been + // opened for writing, so we need to start supporting writable memory + // mappings. This may race with callers of d.pf.FD() using the existing + // FD, so in most cases we need to delay closing the old FD until after + // invalidating memmap.Translations that might have observed it. + if !openReadable || h.fd < 0 { + // We don't have a read/write FD, so we have no FD that can be + // used to create writable memory mappings. Switch to using the + // internal page cache. + invalidateTranslations = true + fdToClose = d.hostFD + d.hostFD = -1 + } else if d.fs.opts.overlayfsStaleRead { + // We do have a read/write FD, but it may not be coherent with + // the existing read-only FD, so we must switch to mappings of + // the new FD in both the application and sentry. + if err := d.pf.hostFileMapper.RegenerateMappings(int(h.fd)); err != nil { d.handleMu.Unlock() - ctx.Warningf("gofer.dentry.ensureSharedHandle: failed to dup fd %d to fd %d: %v", h.fd, d.handle.fd, err) + ctx.Warningf("gofer.dentry.ensureSharedHandle: failed to replace sentry mappings of old FD with mappings of new FD: %v", err) h.close(ctx) return err } - syscall.Close(int(h.fd)) - h.fd = d.handle.fd - if d.fs.opts.overlayfsStaleRead { - // Replace sentry mappings of the old FD with mappings of - // the new FD, since the two are not necessarily coherent. - if err := d.pf.hostFileMapper.RegenerateMappings(int(h.fd)); err != nil { - d.handleMu.Unlock() - ctx.Warningf("gofer.dentry.ensureSharedHandle: failed to replace sentry mappings of old FD with mappings of new FD: %v", err) - h.close(ctx) - return err - } + invalidateTranslations = true + fdToClose = d.hostFD + d.hostFD = h.fd + } else { + // We do have a read/write FD. To avoid invalidating existing + // memmap.Translations (which is expensive), use dup3 to make + // the old file descriptor refer to the new file description, + // then close the new file descriptor (which is no longer + // needed). Racing callers of d.pf.FD() may use the old or new + // file description, but this doesn't matter since they refer + // to the same file, and any racing mappings must be read-only. + if err := syscall.Dup3(int(h.fd), int(d.hostFD), syscall.O_CLOEXEC); err != nil { + oldHostFD := d.hostFD + d.handleMu.Unlock() + ctx.Warningf("gofer.dentry.ensureSharedHandle: failed to dup fd %d to fd %d: %v", h.fd, oldHostFD, err) + h.close(ctx) + return err } - // Clunk the old fid before making the new handle visible (by - // unlocking d.handleMu). - d.handle.file.close(ctx) + fdToClose = h.fd } + } else { + // h.fd is not useful. + fdToClose = h.fd + } + + // Switch to new fids. + var oldReadFile p9file + if openReadable { + oldReadFile = d.readFile + d.readFile = h.file + } + var oldWriteFile p9file + if openWritable { + oldWriteFile = d.writeFile + d.writeFile = h.file + } + // NOTE(b/141991141): Clunk old fids before making new fids visible (by + // unlocking d.handleMu). + if !oldReadFile.isNil() { + oldReadFile.close(ctx) + } + if !oldWriteFile.isNil() && oldReadFile != oldWriteFile { + oldWriteFile.close(ctx) } - // Switch to the new handle. - d.handle = h - d.handleReadable = wantReadable - d.handleWritable = wantWritable } d.handleMu.Unlock() - if d.fs.opts.overlayfsStaleRead && haveOldFD { - // Invalidate application mappings that may be using the old FD; they + if invalidateTranslations { + // Invalidate application mappings that may be using an old FD; they // will be replaced with mappings using the new FD after future calls // to d.Translate(). This requires holding d.mapsMu, which precedes // d.handleMu in the lock order. @@ -1297,28 +1545,70 @@ func (d *dentry) ensureSharedHandle(ctx context.Context, read, write, trunc bool d.mappings.InvalidateAll(memmap.InvalidateOpts{}) d.mapsMu.Unlock() } + if fdToClose >= 0 { + syscall.Close(int(fdToClose)) + } return nil } +// Preconditions: d.handleMu must be locked. +func (d *dentry) readHandleLocked() handle { + return handle{ + file: d.readFile, + fd: d.hostFD, + } +} + +// Preconditions: d.handleMu must be locked. +func (d *dentry) writeHandleLocked() handle { + return handle{ + file: d.writeFile, + fd: d.hostFD, + } +} + +func (d *dentry) syncRemoteFile(ctx context.Context) error { + d.handleMu.RLock() + defer d.handleMu.RUnlock() + return d.syncRemoteFileLocked(ctx) +} + +// Preconditions: d.handleMu must be locked. +func (d *dentry) syncRemoteFileLocked(ctx context.Context) error { + // If we have a host FD, fsyncing it is likely to be faster than an fsync + // RPC. + if d.hostFD >= 0 { + ctx.UninterruptibleSleepStart(false) + err := syscall.Fsync(int(d.hostFD)) + ctx.UninterruptibleSleepFinish(false) + return err + } + if !d.writeFile.isNil() { + return d.writeFile.fsync(ctx) + } + if !d.readFile.isNil() { + return d.readFile.fsync(ctx) + } + return nil +} + // 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 +1616,9 @@ func (d *dentry) decLinks() { type fileDescription struct { vfsfd vfs.FileDescription vfs.FileDescriptionDefaultImpl + vfs.LockFD + + lockLogging sync.Once } func (fd *fileDescription) filesystem() *filesystem { @@ -1354,7 +1647,13 @@ 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(ctx, ev, 0, vfs.InodeEvent) + } + return nil } // Listxattr implements vfs.FileDescriptionImpl.Listxattr. @@ -1369,10 +1668,41 @@ 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(ctx, 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(ctx, 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/gofer_test.go b/pkg/sentry/fsimpl/gofer/gofer_test.go index adff39490..bfe75dfe4 100644 --- a/pkg/sentry/fsimpl/gofer/gofer_test.go +++ b/pkg/sentry/fsimpl/gofer/gofer_test.go @@ -20,10 +20,13 @@ import ( "gvisor.dev/gvisor/pkg/p9" "gvisor.dev/gvisor/pkg/sentry/contexttest" + "gvisor.dev/gvisor/pkg/sentry/pgalloc" ) func TestDestroyIdempotent(t *testing.T) { + ctx := contexttest.Context(t) fs := filesystem{ + mfp: pgalloc.MemoryFileProviderFromContext(ctx), syncableDentries: make(map[*dentry]struct{}), opts: filesystemOptions{ // Test relies on no dentry being held in the cache. @@ -31,7 +34,6 @@ func TestDestroyIdempotent(t *testing.T) { }, } - ctx := contexttest.Context(t) attr := &p9.Attr{ Mode: p9.ModeRegular, } @@ -50,7 +52,9 @@ func TestDestroyIdempotent(t *testing.T) { } parent.cacheNewChildLocked(child, "child") - child.checkCachingLocked() + fs.renameMu.Lock() + defer fs.renameMu.Unlock() + child.checkCachingLocked(ctx) if got := atomic.LoadInt64(&child.refs); got != -1 { t.Fatalf("child.refs=%d, want: -1", got) } @@ -58,6 +62,6 @@ func TestDestroyIdempotent(t *testing.T) { if got := atomic.LoadInt64(&parent.refs); got != -1 { t.Fatalf("parent.refs=%d, want: -1", got) } - child.checkCachingLocked() - child.checkCachingLocked() + child.checkCachingLocked(ctx) + child.checkCachingLocked(ctx) } diff --git a/pkg/sentry/fsimpl/gofer/handle.go b/pkg/sentry/fsimpl/gofer/handle.go index 724a3f1f7..104157512 100644 --- a/pkg/sentry/fsimpl/gofer/handle.go +++ b/pkg/sentry/fsimpl/gofer/handle.go @@ -63,6 +63,10 @@ func openHandle(ctx context.Context, file p9file, read, write, trunc bool) (hand }, nil } +func (h *handle) isOpen() bool { + return !h.file.isNil() +} + func (h *handle) close(ctx context.Context) { h.file.close(ctx) h.file = p9file{} @@ -124,13 +128,3 @@ func (h *handle) writeFromBlocksAt(ctx context.Context, srcs safemem.BlockSeq, o } return cp, cperr } - -func (h *handle) sync(ctx context.Context) error { - if h.fd >= 0 { - ctx.UninterruptibleSleepStart(false) - err := syscall.Fsync(int(h.fd)) - ctx.UninterruptibleSleepFinish(false) - return err - } - 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..7e1cbf065 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" @@ -48,7 +48,7 @@ type regularFileFD struct { } // Release implements vfs.FileDescriptionImpl.Release. -func (fd *regularFileFD) Release() { +func (fd *regularFileFD) Release(context.Context) { } // OnClose implements vfs.FileDescriptionImpl.OnClose. @@ -64,7 +64,37 @@ func (fd *regularFileFD) OnClose(ctx context.Context) error { } d.handleMu.RLock() defer d.handleMu.RUnlock() - return d.handle.file.flush(ctx) + if d.writeFile.isNil() { + return nil + } + return d.writeFile.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() + + // Allocating a smaller size is a noop. + size := offset + length + if d.cachedMetadataAuthoritative() && size <= d.size { + return nil + } + + d.handleMu.RLock() + err := d.writeFile.allocate(ctx, p9.ToAllocateMode(mode), offset, length) + d.handleMu.RUnlock() + 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. @@ -72,14 +102,18 @@ func (fd *regularFileFD) PRead(ctx context.Context, dst usermem.IOSequence, offs 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 } // Check for reading at EOF before calling into MM (but not under // InteropModeShared, which makes d.size unreliable). d := fd.dentry() - if d.fs.opts.interop != InteropModeShared && uint64(offset) >= atomic.LoadUint64(&d.size) { + if d.cachedMetadataAuthoritative() && uint64(offset) >= atomic.LoadUint64(&d.size) { return 0, io.EOF } @@ -120,85 +154,134 @@ 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) - 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 // d.metadataMu (recursively). d.touchCMtimeLocked() } - if fd.vfsfd.StatusFlags()&linux.O_DIRECT != 0 { - // Write dirty cached pages that will be touched by the write back to - // the remote file. - if err := d.writeback(ctx, offset, src.NumBytes()); err != nil { - return 0, err - } - // Remove touched pages from the cache. - pgstart := usermem.PageRoundDown(uint64(offset)) - pgend, ok := usermem.PageRoundUp(uint64(offset + src.NumBytes())) - if !ok { - return 0, syserror.EINVAL - } - mr := memmap.MappableRange{pgstart, pgend} - var freed []platform.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()}) - cseg = d.cache.Remove(cseg).NextSegment() - } - d.dataMu.Unlock() - // Invalidate mappings of removed pages. - d.mapsMu.Lock() - d.mappings.Invalidate(mr, memmap.InvalidateOpts{}) - d.mapsMu.Unlock() - // Finally free pages removed from the cache. - mf := d.fs.mfp.MemoryFile() - for _, freedFR := range freed { - mf.DecRef(freedFR) - } - } + rw := getDentryReadWriter(ctx, d, offset) + defer putDentryReadWriter(rw) + if fd.vfsfd.StatusFlags()&linux.O_DIRECT != 0 { + if err := fd.writeCache(ctx, d, offset, src); err != nil { + return 0, offset, err + } + // Require the write to go to the remote file. rw.direct = true } + n, err := src.CopyInTo(ctx, rw) - putDentryReadWriter(rw) - if n != 0 && fd.vfsfd.StatusFlags()&(linux.O_DSYNC|linux.O_SYNC) != 0 { + if err != nil { + return n, offset + n, err + } + if n > 0 && fd.vfsfd.StatusFlags()&(linux.O_DSYNC|linux.O_SYNC) != 0 { + // Note that if any of the following fail, then we can't guarantee that + // any data was actually written with the semantics of O_DSYNC or + // O_SYNC, so we return zero bytes written. Compare Linux's + // mm/filemap.c:generic_file_write_iter() => + // include/linux/fs.h:generic_write_sync(). + // // Write dirty cached pages touched by the write back to the remote // file. if err := d.writeback(ctx, offset, src.NumBytes()); err != nil { - return 0, err + return 0, offset, err } // Request the remote filesystem to sync the remote file. - if err := d.handle.file.fsync(ctx); err != nil { - return 0, err + if err := d.syncRemoteFile(ctx); err != nil { + return 0, offset, err } } - return n, err + return n, offset + n, nil +} + +func (fd *regularFileFD) writeCache(ctx context.Context, d *dentry, offset int64, src usermem.IOSequence) error { + // Write dirty cached pages that will be touched by the write back to + // the remote file. + if err := d.writeback(ctx, offset, src.NumBytes()); err != nil { + return err + } + + // Remove touched pages from the cache. + pgstart := usermem.PageRoundDown(uint64(offset)) + pgend, ok := usermem.PageRoundUp(uint64(offset + src.NumBytes())) + if !ok { + return syserror.EINVAL + } + mr := memmap.MappableRange{pgstart, pgend} + 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, memmap.FileRange{cseg.Value(), cseg.Value() + cseg.Range().Length()}) + cseg = d.cache.Remove(cseg).NextSegment() + } + d.dataMu.Unlock() + + // Invalidate mappings of removed pages. + d.mapsMu.Lock() + d.mappings.Invalidate(mr, memmap.InvalidateOpts{}) + d.mapsMu.Unlock() + + // Finally free pages removed from the cache. + mf := d.fs.mfp.MemoryFile() + for _, freedFR := range freed { + mf.DecRef(freedFR) + } + return nil } // 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 } @@ -241,10 +324,11 @@ func (rw *dentryReadWriter) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) // coherence with memory-mapped I/O), or if InteropModeShared is in effect // (which prevents us from caching file contents and makes dentry.size // unreliable), or if the file was opened O_DIRECT, read directly from - // dentry.handle without locking dentry.dataMu. + // dentry.readHandleLocked() without locking dentry.dataMu. rw.d.handleMu.RLock() - if (rw.d.handle.fd >= 0 && !rw.d.fs.opts.forcePageCache) || rw.d.fs.opts.interop == InteropModeShared || rw.direct { - n, err := rw.d.handle.readToBlocksAt(rw.ctx, dsts, rw.off) + h := rw.d.readHandleLocked() + if (rw.d.hostFD >= 0 && !rw.d.fs.opts.forcePageCache) || rw.d.fs.opts.interop == InteropModeShared || rw.direct { + n, err := h.readToBlocksAt(rw.ctx, dsts, rw.off) rw.d.handleMu.RUnlock() rw.off += n return n, err @@ -312,7 +396,7 @@ func (rw *dentryReadWriter) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) End: gapEnd, } optMR := gap.Range() - err := rw.d.cache.Fill(rw.ctx, reqMR, maxFillRange(reqMR, optMR), mf, usage.PageCache, rw.d.handle.readToBlocksAt) + err := rw.d.cache.Fill(rw.ctx, reqMR, maxFillRange(reqMR, optMR), mf, usage.PageCache, h.readToBlocksAt) mf.MarkEvictable(rw.d, pgalloc.EvictableRange{optMR.Start, optMR.End}) seg, gap = rw.d.cache.Find(rw.off) if !seg.Ok() { @@ -327,7 +411,7 @@ func (rw *dentryReadWriter) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) } else { // Read directly from the file. gapDsts := dsts.TakeFirst64(gapMR.Length()) - n, err := rw.d.handle.readToBlocksAt(rw.ctx, gapDsts, gapMR.Start) + n, err := h.readToBlocksAt(rw.ctx, gapDsts, gapMR.Start) done += n rw.off += n dsts = dsts.DropFirst64(n) @@ -359,11 +443,12 @@ func (rw *dentryReadWriter) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, erro // If we have a mmappable host FD (which must be used here to ensure // coherence with memory-mapped I/O), or if InteropModeShared is in effect // (which prevents us from caching file contents), or if the file was - // opened with O_DIRECT, write directly to dentry.handle without locking - // dentry.dataMu. + // opened with O_DIRECT, write directly to dentry.writeHandleLocked() + // without locking dentry.dataMu. rw.d.handleMu.RLock() - if (rw.d.handle.fd >= 0 && !rw.d.fs.opts.forcePageCache) || rw.d.fs.opts.interop == InteropModeShared || rw.direct { - n, err := rw.d.handle.writeFromBlocksAt(rw.ctx, srcs, rw.off) + h := rw.d.writeHandleLocked() + if (rw.d.hostFD >= 0 && !rw.d.fs.opts.forcePageCache) || rw.d.fs.opts.interop == InteropModeShared || rw.direct { + n, err := h.writeFromBlocksAt(rw.ctx, srcs, rw.off) rw.off += n rw.d.dataMu.Lock() if rw.off > rw.d.size { @@ -425,7 +510,7 @@ func (rw *dentryReadWriter) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, erro // for detecting or avoiding this. gapMR := gap.Range().Intersect(mr) gapSrcs := srcs.TakeFirst64(gapMR.Length()) - n, err := rw.d.handle.writeFromBlocksAt(rw.ctx, gapSrcs, gapMR.Start) + n, err := h.writeFromBlocksAt(rw.ctx, gapSrcs, gapMR.Start) done += n rw.off += n srcs = srcs.DropFirst64(n) @@ -451,7 +536,7 @@ exitLoop: if err := fsutil.SyncDirty(rw.ctx, memmap.MappableRange{ Start: start, End: rw.off, - }, &rw.d.cache, &rw.d.dirty, rw.d.size, mf, rw.d.handle.writeFromBlocksAt); err != nil { + }, &rw.d.cache, &rw.d.dirty, rw.d.size, mf, h.writeFromBlocksAt); err != nil { // We have no idea how many bytes were actually flushed. rw.off = start done = 0 @@ -469,6 +554,7 @@ func (d *dentry) writeback(ctx context.Context, offset, size int64) error { } d.handleMu.RLock() defer d.handleMu.RUnlock() + h := d.writeHandleLocked() d.dataMu.Lock() defer d.dataMu.Unlock() // Compute the range of valid bytes (overflow-checked). @@ -482,22 +568,31 @@ func (d *dentry) writeback(ctx context.Context, offset, size int64) error { return fsutil.SyncDirty(ctx, memmap.MappableRange{ Start: uint64(offset), End: uint64(end), - }, &d.cache, &d.dirty, d.size, d.fs.mfp.MemoryFile(), d.handle.writeFromBlocksAt) + }, &d.cache, &d.dirty, d.size, d.fs.mfp.MemoryFile(), h.writeFromBlocksAt) } // Seek implements vfs.FileDescriptionImpl.Seek. 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 } @@ -525,31 +620,28 @@ func (fd *regularFileFD) Seek(ctx context.Context, offset int64, whence int32) ( if offset < 0 { return 0, syserror.EINVAL } - fd.off = offset return offset, nil } // Sync implements vfs.FileDescriptionImpl.Sync. func (fd *regularFileFD) Sync(ctx context.Context) error { - return fd.dentry().syncSharedHandle(ctx) + return fd.dentry().syncCachedFile(ctx) } -func (d *dentry) syncSharedHandle(ctx context.Context) error { +func (d *dentry) syncCachedFile(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 h := d.writeHandleLocked(); h.isOpen() { + 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(), h.writeFromBlocksAt) + d.dataMu.Unlock() + if err != nil { + return err + } } - d.handleMu.RUnlock() - return err + return d.syncRemoteFileLocked(ctx) } // ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap. @@ -573,7 +665,7 @@ func (fd *regularFileFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpt return syserror.ENODEV } d.handleMu.RLock() - haveFD := d.handle.fd >= 0 + haveFD := d.hostFD >= 0 d.handleMu.RUnlock() if !haveFD { return syserror.ENODEV @@ -594,7 +686,7 @@ func (d *dentry) mayCachePages() bool { return true } d.handleMu.RLock() - haveFD := d.handle.fd >= 0 + haveFD := d.hostFD >= 0 d.handleMu.RUnlock() return haveFD } @@ -652,7 +744,7 @@ func (d *dentry) CopyMapping(ctx context.Context, ms memmap.MappingSpace, srcAR, // Translate implements memmap.Mappable.Translate. func (d *dentry) Translate(ctx context.Context, required, optional memmap.MappableRange, at usermem.AccessType) ([]memmap.Translation, error) { d.handleMu.RLock() - if d.handle.fd >= 0 && !d.fs.opts.forcePageCache { + if d.hostFD >= 0 && !d.fs.opts.forcePageCache { d.handleMu.RUnlock() mr := optional if d.fs.opts.limitHostFDTranslation { @@ -688,7 +780,8 @@ func (d *dentry) Translate(ctx context.Context, required, optional memmap.Mappab } mf := d.fs.mfp.MemoryFile() - cerr := d.cache.Fill(ctx, required, maxFillRange(required, optional), mf, usage.PageCache, d.handle.readToBlocksAt) + h := d.readHandleLocked() + cerr := d.cache.Fill(ctx, required, maxFillRange(required, optional), mf, usage.PageCache, h.readToBlocksAt) var ts []memmap.Translation var translatedEnd uint64 @@ -747,7 +840,7 @@ 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() @@ -757,9 +850,12 @@ func (d *dentry) InvalidateUnsavable(ctx context.Context) error { // Write the cache's contents back to the remote file so that if we have a // host fd after restore, the remote file's contents are coherent. mf := d.fs.mfp.MemoryFile() + d.handleMu.RLock() + defer d.handleMu.RUnlock() + h := d.writeHandleLocked() d.dataMu.Lock() defer d.dataMu.Unlock() - if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, mf, d.handle.writeFromBlocksAt); err != nil { + if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, mf, h.writeFromBlocksAt); err != nil { return err } @@ -774,20 +870,23 @@ func (d *dentry) InvalidateUnsavable(ctx context.Context) error { // Evict implements pgalloc.EvictableMemoryUser.Evict. func (d *dentry) Evict(ctx context.Context, er pgalloc.EvictableRange) { + mr := memmap.MappableRange{er.Start, er.End} + mf := d.fs.mfp.MemoryFile() d.mapsMu.Lock() defer d.mapsMu.Unlock() + d.handleMu.RLock() + defer d.handleMu.RUnlock() + h := d.writeHandleLocked() d.dataMu.Lock() defer d.dataMu.Unlock() - mr := memmap.MappableRange{er.Start, er.End} - mf := d.fs.mfp.MemoryFile() // Only allow pages that are no longer memory-mapped to be evicted. for mgap := d.mappings.LowerBoundGap(mr.Start); mgap.Ok() && mgap.Start() < mr.End; mgap = mgap.NextGap() { mgapMR := mgap.Range().Intersect(mr) if mgapMR.Length() == 0 { continue } - if err := fsutil.SyncDirty(ctx, mgapMR, &d.cache, &d.dirty, d.size, mf, d.handle.writeFromBlocksAt); err != nil { + if err := fsutil.SyncDirty(ctx, mgapMR, &d.cache, &d.dirty, d.size, mf, h.writeFromBlocksAt); err != nil { log.Warningf("Failed to writeback cached data %v: %v", mgapMR, err) } d.cache.Drop(mgapMR, mf) @@ -795,53 +894,51 @@ 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 -// application memory mappings (i.e. !filesystem.opts.forcePageCache). +// is available (i.e. dentry.hostFD >= 0), and that FD is used for application +// memory mappings (i.e. !filesystem.opts.forcePageCache). 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 - // If this dentry represents a regular file, and handle.fd >= 0, - // hostFileMapper caches mappings of handle.fd. + // If this dentry represents a regular file, and dentry.hostFD >= 0, + // hostFileMapper caches mappings of dentry.hostFD. hostFileMapper fsutil.HostFileMapper // hostFileMapperInitOnce is used to lazily initialize hostFileMapper. 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 + defer d.handleMu.RUnlock() + return d.hostFileMapper.MapInternal(fr, int(d.hostFD), at.Write) } -// FD implements platform.File.FD. +// FD implements memmap.File.FD. func (d *dentryPlatformFile) FD() int { d.handleMu.RLock() - fd := d.handle.fd - d.handleMu.RUnlock() - return int(fd) + defer d.handleMu.RUnlock() + return int(d.hostFD) } diff --git a/pkg/sentry/fsimpl/gofer/socket.go b/pkg/sentry/fsimpl/gofer/socket.go index d6dbe9092..85d2bee72 100644 --- a/pkg/sentry/fsimpl/gofer/socket.go +++ b/pkg/sentry/fsimpl/gofer/socket.go @@ -108,7 +108,7 @@ func (e *endpoint) UnidirectionalConnect(ctx context.Context) (transport.Connect // We don't need the receiver. c.CloseRecv() - c.Release() + c.Release(ctx) return c, nil } @@ -136,8 +136,8 @@ func (e *endpoint) newConnectedEndpoint(ctx context.Context, flags p9.ConnectFla } // Release implements transport.BoundEndpoint.Release. -func (e *endpoint) Release() { - e.dentry.DecRef() +func (e *endpoint) Release(ctx context.Context) { + e.dentry.DecRef(ctx) } // Passcred implements transport.BoundEndpoint.Passcred. diff --git a/pkg/sentry/fsimpl/gofer/special_file.go b/pkg/sentry/fsimpl/gofer/special_file.go index a464e6a94..a6368fdd0 100644 --- a/pkg/sentry/fsimpl/gofer/special_file.go +++ b/pkg/sentry/fsimpl/gofer/special_file.go @@ -16,20 +16,23 @@ package gofer import ( "sync" + "sync/atomic" + "syscall" "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 @@ -40,14 +43,49 @@ 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() { - fd.handle.close(context.Background()) +func (fd *specialFileFD) Release(ctx context.Context) { + if fd.haveQueue { + fdnotifier.RemoveFD(fd.handle.fd) + } + fd.handle.close(ctx) fs := fd.vfsfd.Mount().Filesystem().Impl().(*filesystem) fs.syncMu.Lock() delete(fs.specialFileFDs, fd) @@ -62,12 +100,44 @@ 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 +146,14 @@ 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 +178,76 @@ 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 +257,8 @@ 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 +270,23 @@ 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 + // If we have a host FD, fsyncing it is likely to be faster than an fsync + // RPC. + if fd.handle.fd >= 0 { + ctx.UninterruptibleSleepStart(false) + err := syscall.Fsync(int(fd.handle.fd)) + ctx.UninterruptibleSleepFinish(false) + return err } - return fd.handle.sync(ctx) + return fd.handle.file.fsync(ctx) } diff --git a/pkg/sentry/fsimpl/gofer/time.go b/pkg/sentry/fsimpl/gofer/time.go index 2608e7e1d..2cb8191b9 100644 --- a/pkg/sentry/fsimpl/gofer/time.go +++ b/pkg/sentry/fsimpl/gofer/time.go @@ -36,20 +36,24 @@ 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 } now := d.fs.clock.Now().Nanoseconds() d.metadataMu.Lock() atomic.StoreInt64(&d.atime, now) + atomic.StoreUint32(&d.atimeDirty, 1) d.metadataMu.Unlock() 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() @@ -57,18 +61,22 @@ 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() atomic.StoreInt64(&d.mtime, now) atomic.StoreInt64(&d.ctime, now) + atomic.StoreUint32(&d.mtimeDirty, 1) 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) atomic.StoreInt64(&d.ctime, now) + atomic.StoreUint32(&d.mtimeDirty, 1) } |