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-rw-r--r--pkg/sentry/fsimpl/gofer/filesystem.go1087
1 files changed, 1087 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
new file mode 100644
index 000000000..8eb61debf
--- /dev/null
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -0,0 +1,1087 @@
+// 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 (
+ "sync"
+
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
+ "gvisor.dev/gvisor/pkg/fspath"
+ "gvisor.dev/gvisor/pkg/p9"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
+ "gvisor.dev/gvisor/pkg/syserror"
+)
+
+// Sync implements vfs.FilesystemImpl.Sync.
+func (fs *filesystem) Sync(ctx context.Context) error {
+ // Snapshot current dentries and special files.
+ fs.syncMu.Lock()
+ ds := make([]*dentry, 0, len(fs.dentries))
+ for d := range fs.dentries {
+ ds = append(ds, d)
+ }
+ sffds := make([]*specialFileFD, 0, len(fs.specialFileFDs))
+ for sffd := range fs.specialFileFDs {
+ sffds = append(sffds, sffd)
+ }
+ fs.syncMu.Unlock()
+
+ // Return the first error we encounter, but sync everything we can
+ // regardless.
+ var retErr error
+
+ // Sync regular files.
+ for _, d := range ds {
+ if !d.TryIncRef() {
+ continue
+ }
+ err := d.syncSharedHandle(ctx)
+ d.DecRef()
+ if err != nil && retErr == nil {
+ retErr = err
+ }
+ }
+
+ // Sync special files, which may be writable but do not use dentry shared
+ // handles (so they won't be synced by the above).
+ for _, sffd := range sffds {
+ if !sffd.vfsfd.TryIncRef() {
+ continue
+ }
+ err := sffd.Sync(ctx)
+ sffd.vfsfd.DecRef()
+ if err != nil && retErr == nil {
+ retErr = err
+ }
+ }
+
+ return retErr
+}
+
+// maxFilenameLen is the maximum length of a filename. This is dictated by 9P's
+// encoding of strings, which uses 2 bytes for the length prefix.
+const maxFilenameLen = (1 << 16) - 1
+
+// dentrySlicePool is a pool of *[]*dentry used to store dentries for which
+// dentry.checkCachingLocked() must be called. The pool holds pointers to
+// slices because Go lacks generics, so sync.Pool operates on interface{}, so
+// every call to (what should be) sync.Pool<[]*dentry>.Put() allocates a copy
+// of the slice header on the heap.
+var dentrySlicePool = sync.Pool{
+ New: func() interface{} {
+ ds := make([]*dentry, 0, 4) // arbitrary non-zero initial capacity
+ return &ds
+ },
+}
+
+func appendDentry(ds *[]*dentry, d *dentry) *[]*dentry {
+ if ds == nil {
+ ds = dentrySlicePool.Get().(*[]*dentry)
+ }
+ *ds = append(*ds, d)
+ return ds
+}
+
+// Preconditions: ds != nil.
+func putDentrySlice(ds *[]*dentry) {
+ // Allow dentries to be GC'd.
+ for i := range *ds {
+ (*ds)[i] = nil
+ }
+ *ds = (*ds)[:0]
+ dentrySlicePool.Put(ds)
+}
+
+// stepLocked resolves rp.Component() to an existing file, starting from the
+// given directory.
+//
+// Dentries which may become cached as a result of the traversal are appended
+// to *ds.
+//
+// Preconditions: fs.renameMu must be locked. d.dirMu must be locked.
+// !rp.Done(). If fs.opts.interop == InteropModeShared, then d's cached
+// metadata must be up to date.
+func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, ds **[]*dentry) (*dentry, error) {
+ if !d.isDir() {
+ return nil, syserror.ENOTDIR
+ }
+ if err := d.checkPermissions(rp.Credentials(), vfs.MayExec, true); err != nil {
+ return nil, err
+ }
+afterSymlink:
+ name := rp.Component()
+ if name == "." {
+ rp.Advance()
+ return d, nil
+ }
+ if name == ".." {
+ parentVFSD, err := rp.ResolveParent(&d.vfsd)
+ if err != nil {
+ return nil, err
+ }
+ parent := parentVFSD.Impl().(*dentry)
+ if fs.opts.interop == InteropModeShared {
+ // We must assume that parentVFSD is correct, because if d has been
+ // moved elsewhere in the remote filesystem so that its parent has
+ // changed, we have no way of determining its new parent's location
+ // in the filesystem. Get updated metadata for parentVFSD.
+ _, attrMask, attr, err := parent.file.getAttr(ctx, dentryAttrMask())
+ if err != nil {
+ return nil, err
+ }
+ parent.updateFromP9Attrs(attrMask, &attr)
+ }
+ rp.Advance()
+ return parent, nil
+ }
+ childVFSD, err := rp.ResolveChild(&d.vfsd, name)
+ if err != nil {
+ return nil, err
+ }
+ // FIXME(jamieliu): Linux performs revalidation before mount lookup
+ // (fs/namei.c:lookup_fast() => __d_lookup_rcu(), d_revalidate(),
+ // __follow_mount_rcu()).
+ child, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), d, name, childVFSD, ds)
+ if err != nil {
+ return nil, err
+ }
+ if child == nil {
+ return nil, syserror.ENOENT
+ }
+ if child.isSymlink() && rp.ShouldFollowSymlink() {
+ target, err := child.readlink(ctx, rp.Mount())
+ if err != nil {
+ return nil, err
+ }
+ if err := rp.HandleSymlink(target); err != nil {
+ return nil, err
+ }
+ goto afterSymlink // don't check the current directory again
+ }
+ rp.Advance()
+ return child, nil
+}
+
+// revalidateChildLocked must be called after a call to parent.vfsd.Child(name)
+// or vfs.ResolvingPath.ResolveChild(name) returns childVFSD (which may be
+// nil) to verify that the returned child (or lack thereof) is correct. If no file
+// exists at name, revalidateChildLocked returns (nil, nil).
+//
+// Preconditions: fs.renameMu must be locked. parent.dirMu must be locked.
+// parent.isDir(). name is not "." or "..".
+//
+// Postconditions: If revalidateChildLocked returns a non-nil dentry, its
+// cached metadata is up to date.
+func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *dentry, name string, childVFSD *vfs.Dentry, ds **[]*dentry) (*dentry, error) {
+ if childVFSD != nil && fs.opts.interop != InteropModeShared {
+ // We have a cached dentry that is assumed to be correct.
+ return childVFSD.Impl().(*dentry), nil
+ }
+ // We either don't have a cached dentry or need to verify that it's still
+ // correct, either of which requires a remote lookup. Check if this name is
+ // valid before performing the lookup.
+ if len(name) > maxFilenameLen {
+ return nil, syserror.ENAMETOOLONG
+ }
+ // Check if we've already cached this lookup with a negative result.
+ if _, ok := parent.negativeChildren[name]; ok {
+ return nil, nil
+ }
+ // Perform the remote lookup.
+ qid, file, attrMask, attr, err := parent.file.walkGetAttrOne(ctx, name)
+ if err != nil && err != syserror.ENOENT {
+ return nil, err
+ }
+ if childVFSD != nil {
+ child := childVFSD.Impl().(*dentry)
+ if !file.isNil() && qid.Path == child.ino {
+ // The file at this path hasn't changed. Just update cached
+ // metadata.
+ file.close(ctx)
+ child.updateFromP9Attrs(attrMask, &attr)
+ return child, nil
+ }
+ // The file at this path has changed or no longer exists. Remove
+ // the stale dentry from the tree, and re-evaluate its caching
+ // status (i.e. if it has 0 references, drop it).
+ vfsObj.ForceDeleteDentry(childVFSD)
+ *ds = appendDentry(*ds, child)
+ childVFSD = nil
+ }
+ if file.isNil() {
+ // No file exists at this path now. Cache the negative lookup if
+ // allowed.
+ if fs.opts.interop != InteropModeShared {
+ parent.cacheNegativeChildLocked(name)
+ }
+ return nil, nil
+ }
+ // Create a new dentry representing the file.
+ child, err := fs.newDentry(ctx, file, qid, attrMask, &attr)
+ if err != nil {
+ file.close(ctx)
+ return nil, err
+ }
+ parent.IncRef() // reference held by child on its parent
+ parent.vfsd.InsertChild(&child.vfsd, name)
+ // For now, child has 0 references, so our caller should call
+ // child.checkCachingLocked().
+ *ds = appendDentry(*ds, child)
+ return child, nil
+}
+
+// walkParentDirLocked resolves all but the last path component of rp to an
+// existing directory, starting from the given directory (which is usually
+// rp.Start().Impl().(*dentry)). It does not check that the returned directory
+// is searchable by the provider of rp.
+//
+// Preconditions: fs.renameMu must be locked. !rp.Done(). If fs.opts.interop ==
+// InteropModeShared, then d's cached metadata must be up to date.
+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)
+ d.dirMu.Unlock()
+ if err != nil {
+ return nil, err
+ }
+ d = next
+ }
+ if !d.isDir() {
+ return nil, syserror.ENOTDIR
+ }
+ return d, nil
+}
+
+// resolveLocked resolves rp to an existing file.
+//
+// Preconditions: fs.renameMu must be locked.
+func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath, ds **[]*dentry) (*dentry, error) {
+ d := rp.Start().Impl().(*dentry)
+ if fs.opts.interop == InteropModeShared {
+ // Get updated metadata for rp.Start() as required by fs.stepLocked().
+ if err := d.updateFromGetattr(ctx); err != nil {
+ return nil, err
+ }
+ }
+ for !rp.Done() {
+ d.dirMu.Lock()
+ next, err := fs.stepLocked(ctx, rp, d, ds)
+ d.dirMu.Unlock()
+ if err != nil {
+ return nil, err
+ }
+ d = next
+ }
+ if rp.MustBeDir() && !d.isDir() {
+ return nil, syserror.ENOTDIR
+ }
+ return d, nil
+}
+
+// doCreateAt checks that creating a file at rp is permitted, then invokes
+// create to do so.
+//
+// Preconditions: !rp.Done(). For the final path component in rp,
+// !rp.ShouldFollowSymlink().
+func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool, create func(parent *dentry, name string) error) error {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ start := rp.Start().Impl().(*dentry)
+ if fs.opts.interop == InteropModeShared {
+ // Get updated metadata for start as required by
+ // fs.walkParentDirLocked().
+ if err := start.updateFromGetattr(ctx); err != nil {
+ return err
+ }
+ }
+ parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
+ if err != nil {
+ return err
+ }
+ if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec, true); err != nil {
+ return err
+ }
+ if parent.isDeleted() {
+ return syserror.ENOENT
+ }
+ name := rp.Component()
+ if name == "." || name == ".." {
+ return syserror.EEXIST
+ }
+ if len(name) > maxFilenameLen {
+ return syserror.ENAMETOOLONG
+ }
+ if !dir && rp.MustBeDir() {
+ return syserror.ENOENT
+ }
+ mnt := rp.Mount()
+ if err := mnt.CheckBeginWrite(); err != nil {
+ return err
+ }
+ defer mnt.EndWrite()
+ parent.dirMu.Lock()
+ defer parent.dirMu.Unlock()
+ 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 create(parent, name)
+ }
+ if parent.vfsd.Child(name) != nil {
+ return syserror.EEXIST
+ }
+ // No cached dentry exists; however, there might still be an existing file
+ // at name. As above, we attempt the file creation RPC anyway.
+ if err := create(parent, name); err != nil {
+ return err
+ }
+ parent.touchCMtime(ctx)
+ delete(parent.negativeChildren, name)
+ parent.dirents = nil
+ return nil
+}
+
+// Preconditions: !rp.Done().
+func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool) error {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ start := rp.Start().Impl().(*dentry)
+ if fs.opts.interop == InteropModeShared {
+ // Get updated metadata for start as required by
+ // fs.walkParentDirLocked().
+ if err := start.updateFromGetattr(ctx); err != nil {
+ return err
+ }
+ }
+ parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
+ if err != nil {
+ return err
+ }
+ if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec, true); err != nil {
+ return err
+ }
+ if err := rp.Mount().CheckBeginWrite(); err != nil {
+ return err
+ }
+ defer rp.Mount().EndWrite()
+
+ name := rp.Component()
+ if dir {
+ if name == "." {
+ return syserror.EINVAL
+ }
+ if name == ".." {
+ return syserror.ENOTEMPTY
+ }
+ } else {
+ if name == "." || name == ".." {
+ return syserror.EISDIR
+ }
+ }
+ vfsObj := rp.VirtualFilesystem()
+ mntns := vfs.MountNamespaceFromContext(ctx)
+ parent.dirMu.Lock()
+ defer parent.dirMu.Unlock()
+ childVFSD := parent.vfsd.Child(name)
+ var child *dentry
+ // We only need a dentry representing the file at name if it can be a mount
+ // point. If childVFSD is nil, then it can't be a mount point. If childVFSD
+ // 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).
+ if childVFSD != nil {
+ child = childVFSD.Impl().(*dentry)
+ if err := vfsObj.PrepareDeleteDentry(mntns, childVFSD); err != nil {
+ child, err = fs.revalidateChildLocked(ctx, vfsObj, parent, name, childVFSD, &ds)
+ if err != nil {
+ return err
+ }
+ if child != nil {
+ childVFSD = &child.vfsd
+ if err := vfsObj.PrepareDeleteDentry(mntns, childVFSD); err != nil {
+ return err
+ }
+ } else {
+ childVFSD = nil
+ }
+ }
+ } else if _, ok := parent.negativeChildren[name]; ok {
+ return syserror.ENOENT
+ }
+ flags := uint32(0)
+ if dir {
+ if child != nil && !child.isDir() {
+ return syserror.ENOTDIR
+ }
+ flags = linux.AT_REMOVEDIR
+ } else {
+ if child != nil && child.isDir() {
+ return syserror.EISDIR
+ }
+ if rp.MustBeDir() {
+ return syserror.ENOTDIR
+ }
+ }
+ err = parent.file.unlinkAt(ctx, name, flags)
+ if err != nil {
+ if childVFSD != nil {
+ vfsObj.AbortDeleteDentry(childVFSD)
+ }
+ return err
+ }
+ if fs.opts.interop != InteropModeShared {
+ parent.touchCMtime(ctx)
+ parent.cacheNegativeChildLocked(name)
+ parent.dirents = nil
+ }
+ if child != nil {
+ child.setDeleted()
+ vfsObj.CommitDeleteDentry(childVFSD)
+ ds = appendDentry(ds, child)
+ }
+ return nil
+}
+
+// renameMuRUnlockAndCheckCaching calls fs.renameMu.RUnlock(), then calls
+// dentry.checkCachingLocked on all dentries in *ds with fs.renameMu locked for
+// writing.
+//
+// ds is a pointer-to-pointer since defer evaluates its arguments immediately,
+// but dentry slices are allocated lazily, and it's much easier to say "defer
+// fs.renameMuRUnlockAndCheckCaching(&ds)" than "defer func() {
+// fs.renameMuRUnlockAndCheckCaching(ds) }()" to work around this.
+func (fs *filesystem) renameMuRUnlockAndCheckCaching(ds **[]*dentry) {
+ fs.renameMu.RUnlock()
+ if *ds == nil {
+ return
+ }
+ if len(**ds) != 0 {
+ fs.renameMu.Lock()
+ for _, d := range **ds {
+ d.checkCachingLocked()
+ }
+ fs.renameMu.Unlock()
+ }
+ putDentrySlice(*ds)
+}
+
+func (fs *filesystem) renameMuUnlockAndCheckCaching(ds **[]*dentry) {
+ if *ds == nil {
+ fs.renameMu.Unlock()
+ return
+ }
+ for _, d := range **ds {
+ d.checkCachingLocked()
+ }
+ fs.renameMu.Unlock()
+ putDentrySlice(*ds)
+}
+
+// GetDentryAt implements vfs.FilesystemImpl.GetDentryAt.
+func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetDentryOptions) (*vfs.Dentry, error) {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return nil, err
+ }
+ if opts.CheckSearchable {
+ if !d.isDir() {
+ return nil, syserror.ENOTDIR
+ }
+ if err := d.checkPermissions(rp.Credentials(), vfs.MayExec, true); err != nil {
+ return nil, err
+ }
+ }
+ d.IncRef()
+ return &d.vfsd, nil
+}
+
+// GetParentDentryAt implements vfs.FilesystemImpl.GetParentDentryAt.
+func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, error) {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ start := rp.Start().Impl().(*dentry)
+ if fs.opts.interop == InteropModeShared {
+ // Get updated metadata for start as required by
+ // fs.walkParentDirLocked().
+ if err := start.updateFromGetattr(ctx); err != nil {
+ return nil, err
+ }
+ }
+ d, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
+ if err != nil {
+ return nil, err
+ }
+ d.IncRef()
+ return &d.vfsd, nil
+}
+
+// LinkAt implements vfs.FilesystemImpl.LinkAt.
+func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error {
+ return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string) error {
+ if rp.Mount() != vd.Mount() {
+ return syserror.EXDEV
+ }
+ // 9P2000.L supports hard links, but we don't.
+ return syserror.EPERM
+ })
+}
+
+// MkdirAt implements vfs.FilesystemImpl.MkdirAt.
+func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error {
+ return fs.doCreateAt(ctx, rp, true /* dir */, func(parent *dentry, name string) error {
+ creds := rp.Credentials()
+ _, err := parent.file.mkdir(ctx, name, (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID))
+ return err
+ })
+}
+
+// MknodAt implements vfs.FilesystemImpl.MknodAt.
+func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error {
+ return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string) error {
+ creds := rp.Credentials()
+ _, err := parent.file.mknod(ctx, name, (p9.FileMode)(opts.Mode), opts.DevMajor, opts.DevMinor, (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID))
+ return err
+ })
+}
+
+// OpenAt implements vfs.FilesystemImpl.OpenAt.
+func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
+ // Reject O_TMPFILE, which is not supported; supporting it correctly in the
+ // presence of other remote filesystem users requires remote filesystem
+ // support, and it isn't clear that there's any way to implement this in
+ // 9P.
+ if opts.Flags&linux.O_TMPFILE != 0 {
+ return nil, syserror.EOPNOTSUPP
+ }
+ mayCreate := opts.Flags&linux.O_CREAT != 0
+ mustCreate := opts.Flags&(linux.O_CREAT|linux.O_EXCL) == (linux.O_CREAT | linux.O_EXCL)
+
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+
+ start := rp.Start().Impl().(*dentry)
+ if fs.opts.interop == InteropModeShared {
+ // Get updated metadata for start as required by fs.stepLocked().
+ if err := start.updateFromGetattr(ctx); err != nil {
+ return nil, err
+ }
+ }
+ if rp.Done() {
+ return start.openLocked(ctx, rp, opts.Flags)
+ }
+
+afterTrailingSymlink:
+ parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
+ if err != nil {
+ return nil, err
+ }
+ // Check for search permission in the parent directory.
+ if err := parent.checkPermissions(rp.Credentials(), vfs.MayExec, true); err != nil {
+ return nil, err
+ }
+ // Determine whether or not we need to create a file.
+ parent.dirMu.Lock()
+ child, err := fs.stepLocked(ctx, rp, parent, &ds)
+ if err == syserror.ENOENT && mayCreate {
+ fd, err := parent.createAndOpenChildLocked(ctx, rp, &opts)
+ parent.dirMu.Unlock()
+ return fd, err
+ }
+ if err != nil {
+ parent.dirMu.Unlock()
+ return nil, err
+ }
+ // Open existing child or follow symlink.
+ parent.dirMu.Unlock()
+ if mustCreate {
+ return nil, syserror.EEXIST
+ }
+ if child.isSymlink() && rp.ShouldFollowSymlink() {
+ target, err := child.readlink(ctx, rp.Mount())
+ if err != nil {
+ return nil, err
+ }
+ if err := rp.HandleSymlink(target); err != nil {
+ return nil, err
+ }
+ start = parent
+ goto afterTrailingSymlink
+ }
+ return child.openLocked(ctx, rp, opts.Flags)
+}
+
+// Preconditions: fs.renameMu must be locked.
+func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, flags uint32) (*vfs.FileDescription, error) {
+ ats := vfs.AccessTypesForOpenFlags(flags)
+ if err := d.checkPermissions(rp.Credentials(), ats, d.isDir()); err != nil {
+ return nil, err
+ }
+ mnt := rp.Mount()
+ filetype := d.fileType()
+ switch {
+ case filetype == linux.S_IFREG && !d.fs.opts.regularFilesUseSpecialFileFD:
+ if err := d.ensureSharedHandle(ctx, ats&vfs.MayRead != 0, ats&vfs.MayWrite != 0, flags&linux.O_TRUNC != 0); err != nil {
+ return nil, err
+ }
+ fd := &regularFileFD{}
+ if err := fd.vfsfd.Init(fd, flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{
+ AllowDirectIO: true,
+ }); err != nil {
+ return nil, err
+ }
+ return &fd.vfsfd, nil
+ case filetype == linux.S_IFDIR:
+ // Can't open directories with O_CREAT.
+ if flags&linux.O_CREAT != 0 {
+ return nil, syserror.EISDIR
+ }
+ // Can't open directories writably.
+ if ats&vfs.MayWrite != 0 {
+ return nil, syserror.EISDIR
+ }
+ if flags&linux.O_DIRECT != 0 {
+ return nil, syserror.EINVAL
+ }
+ if err := d.ensureSharedHandle(ctx, ats&vfs.MayRead != 0, false /* write */, false /* trunc */); err != nil {
+ return nil, err
+ }
+ fd := &directoryFD{}
+ if err := fd.vfsfd.Init(fd, flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
+ return nil, err
+ }
+ return &fd.vfsfd, nil
+ case filetype == linux.S_IFLNK:
+ // Can't open symlinks without O_PATH (which is unimplemented).
+ return nil, syserror.ELOOP
+ default:
+ if flags&linux.O_DIRECT != 0 {
+ return nil, syserror.EINVAL
+ }
+ h, err := openHandle(ctx, d.file, ats&vfs.MayRead != 0, ats&vfs.MayWrite != 0, flags&linux.O_TRUNC != 0)
+ if err != nil {
+ return nil, err
+ }
+ fd := &specialFileFD{
+ handle: h,
+ }
+ if err := fd.vfsfd.Init(fd, flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
+ h.close(ctx)
+ return nil, err
+ }
+ return &fd.vfsfd, nil
+ }
+}
+
+// Preconditions: d.fs.renameMu must be locked. d.dirMu must be locked.
+func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions) (*vfs.FileDescription, error) {
+ if err := d.checkPermissions(rp.Credentials(), vfs.MayWrite, true); err != nil {
+ return nil, err
+ }
+ if d.isDeleted() {
+ return nil, syserror.ENOENT
+ }
+ mnt := rp.Mount()
+ if err := mnt.CheckBeginWrite(); err != nil {
+ return nil, err
+ }
+ defer mnt.EndWrite()
+
+ // 9P2000.L's lcreate takes a fid representing the parent directory, and
+ // converts it into an open fid representing the created file, so we need
+ // to duplicate the directory fid first.
+ _, dirfile, err := d.file.walk(ctx, nil)
+ if err != nil {
+ return nil, err
+ }
+ creds := rp.Credentials()
+ name := rp.Component()
+ fdobj, openFile, createQID, _, err := dirfile.create(ctx, name, (p9.OpenFlags)(opts.Flags), (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID))
+ if err != nil {
+ dirfile.close(ctx)
+ return nil, err
+ }
+ // Then we need to walk to the file we just created to get a non-open fid
+ // representing it, and to get its metadata. This must use d.file since, as
+ // explained above, dirfile was invalidated by dirfile.Create().
+ walkQID, nonOpenFile, attrMask, attr, err := d.file.walkGetAttrOne(ctx, name)
+ if err != nil {
+ openFile.close(ctx)
+ if fdobj != nil {
+ fdobj.Close()
+ }
+ return nil, err
+ }
+ // Sanity-check that we walked to the file we created.
+ if createQID.Path != walkQID.Path {
+ // Probably due to concurrent remote filesystem mutation?
+ ctx.Warningf("gofer.dentry.createAndOpenChildLocked: created file has QID %v before walk, QID %v after (interop=%v)", createQID, walkQID, d.fs.opts.interop)
+ nonOpenFile.close(ctx)
+ openFile.close(ctx)
+ if fdobj != nil {
+ fdobj.Close()
+ }
+ return nil, syserror.EAGAIN
+ }
+
+ // Construct the new dentry.
+ child, err := d.fs.newDentry(ctx, nonOpenFile, createQID, attrMask, &attr)
+ if err != nil {
+ nonOpenFile.close(ctx)
+ openFile.close(ctx)
+ if fdobj != nil {
+ fdobj.Close()
+ }
+ return nil, err
+ }
+ // 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())
+ }
+ 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.IncRef() // reference held by child on its parent d
+ d.vfsd.InsertChild(&child.vfsd, name)
+ if d.fs.opts.interop != InteropModeShared {
+ d.touchCMtime(ctx)
+ delete(d.negativeChildren, name)
+ d.dirents = nil
+ }
+
+ // Finally, construct a file description representing the created file.
+ var childVFSFD *vfs.FileDescription
+ mnt.IncRef()
+ if useRegularFileFD {
+ fd := &regularFileFD{}
+ if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &child.vfsd, &vfs.FileDescriptionOptions{
+ AllowDirectIO: true,
+ }); err != nil {
+ return nil, err
+ }
+ childVFSFD = &fd.vfsfd
+ } else {
+ fd := &specialFileFD{
+ handle: handle{
+ file: openFile,
+ fd: -1,
+ },
+ }
+ if fdobj != nil {
+ fd.handle.fd = int32(fdobj.Release())
+ }
+ if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &child.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
+ fd.handle.close(ctx)
+ return nil, err
+ }
+ childVFSFD = &fd.vfsfd
+ }
+ return childVFSFD, nil
+}
+
+// ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt.
+func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (string, error) {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return "", err
+ }
+ if !d.isSymlink() {
+ return "", syserror.EINVAL
+ }
+ return d.readlink(ctx, rp.Mount())
+}
+
+// RenameAt implements vfs.FilesystemImpl.RenameAt.
+func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldParentVD vfs.VirtualDentry, oldName string, opts vfs.RenameOptions) error {
+ if opts.Flags != 0 {
+ // Requires 9P support.
+ return syserror.EINVAL
+ }
+
+ var ds *[]*dentry
+ fs.renameMu.Lock()
+ defer fs.renameMuUnlockAndCheckCaching(&ds)
+ newParent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*dentry), &ds)
+ if err != nil {
+ return err
+ }
+ newName := rp.Component()
+ if newName == "." || newName == ".." {
+ return syserror.EBUSY
+ }
+ mnt := rp.Mount()
+ if mnt != oldParentVD.Mount() {
+ return syserror.EXDEV
+ }
+ if err := mnt.CheckBeginWrite(); err != nil {
+ return err
+ }
+ defer mnt.EndWrite()
+
+ oldParent := oldParentVD.Dentry().Impl().(*dentry)
+ if fs.opts.interop == InteropModeShared {
+ if err := oldParent.updateFromGetattr(ctx); err != nil {
+ return err
+ }
+ }
+ if err := oldParent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec, true); err != nil {
+ return err
+ }
+ vfsObj := rp.VirtualFilesystem()
+ // We need a dentry representing the renamed file since, if it's a
+ // directory, we need to check for write permission on it.
+ oldParent.dirMu.Lock()
+ defer oldParent.dirMu.Unlock()
+ renamed, err := fs.revalidateChildLocked(ctx, vfsObj, oldParent, oldName, oldParent.vfsd.Child(oldName), &ds)
+ if err != nil {
+ return err
+ }
+ if renamed == nil {
+ return syserror.ENOENT
+ }
+ if renamed.isDir() {
+ if renamed == newParent || renamed.vfsd.IsAncestorOf(&newParent.vfsd) {
+ return syserror.EINVAL
+ }
+ if oldParent != newParent {
+ if err := renamed.checkPermissions(rp.Credentials(), vfs.MayWrite, true); err != nil {
+ return err
+ }
+ }
+ } else {
+ if opts.MustBeDir || rp.MustBeDir() {
+ return syserror.ENOTDIR
+ }
+ }
+
+ if oldParent != newParent {
+ if err := newParent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec, true); err != nil {
+ return err
+ }
+ newParent.dirMu.Lock()
+ defer newParent.dirMu.Unlock()
+ }
+ if newParent.isDeleted() {
+ return syserror.ENOENT
+ }
+ replacedVFSD := newParent.vfsd.Child(newName)
+ var replaced *dentry
+ // This is similar to unlinkAt, except:
+ //
+ // - We revalidate the replaced dentry unconditionally for simplicity.
+ //
+ // - If rp.MustBeDir(), then we need a dentry representing the replaced
+ // file regardless to confirm that it's a directory.
+ if replacedVFSD != nil || rp.MustBeDir() {
+ replaced, err = fs.revalidateChildLocked(ctx, vfsObj, newParent, newName, replacedVFSD, &ds)
+ if err != nil {
+ return err
+ }
+ if replaced != nil {
+ if replaced.isDir() {
+ if !renamed.isDir() {
+ return syserror.EISDIR
+ }
+ } else {
+ if rp.MustBeDir() || renamed.isDir() {
+ return syserror.ENOTDIR
+ }
+ }
+ replacedVFSD = &replaced.vfsd
+ } else {
+ replacedVFSD = nil
+ }
+ }
+
+ if oldParent == newParent && oldName == newName {
+ return nil
+ }
+ if err := vfsObj.PrepareRenameDentry(vfs.MountNamespaceFromContext(ctx), &renamed.vfsd, replacedVFSD); err != nil {
+ return err
+ }
+ if err := renamed.file.rename(ctx, newParent.file, newName); err != nil {
+ vfsObj.AbortRenameDentry(&renamed.vfsd, replacedVFSD)
+ return err
+ }
+ if fs.opts.interop != InteropModeShared {
+ oldParent.cacheNegativeChildLocked(oldName)
+ oldParent.dirents = nil
+ delete(newParent.negativeChildren, newName)
+ newParent.dirents = nil
+ }
+ vfsObj.CommitRenameReplaceDentry(&renamed.vfsd, &newParent.vfsd, newName, replacedVFSD)
+ return nil
+}
+
+// RmdirAt implements vfs.FilesystemImpl.RmdirAt.
+func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error {
+ return fs.unlinkAt(ctx, rp, true /* dir */)
+}
+
+// SetStatAt implements vfs.FilesystemImpl.SetStatAt.
+func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return err
+ }
+ return d.setStat(ctx, rp.Credentials(), &opts.Stat, rp.Mount())
+}
+
+// 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)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return linux.Statx{}, err
+ }
+ // Since walking updates metadata for all traversed dentries under
+ // InteropModeShared, including the returned one, we can return cached
+ // metadata here regardless of fs.opts.interop.
+ var stat linux.Statx
+ d.statTo(&stat)
+ return stat, nil
+}
+
+// StatFSAt implements vfs.FilesystemImpl.StatFSAt.
+func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linux.Statfs, error) {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return linux.Statfs{}, err
+ }
+ fsstat, err := d.file.statFS(ctx)
+ if err != nil {
+ return linux.Statfs{}, err
+ }
+ nameLen := uint64(fsstat.NameLength)
+ if nameLen > maxFilenameLen {
+ nameLen = maxFilenameLen
+ }
+ return linux.Statfs{
+ // This is primarily for distinguishing a gofer file system in
+ // tests. Testing is important, so instead of defining
+ // something completely random, use a standard value.
+ Type: linux.V9FS_MAGIC,
+ BlockSize: int64(fsstat.BlockSize),
+ Blocks: fsstat.Blocks,
+ BlocksFree: fsstat.BlocksFree,
+ BlocksAvailable: fsstat.BlocksAvailable,
+ Files: fsstat.Files,
+ FilesFree: fsstat.FilesFree,
+ NameLength: nameLen,
+ }, nil
+}
+
+// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt.
+func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error {
+ return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string) error {
+ creds := rp.Credentials()
+ _, err := parent.file.symlink(ctx, target, name, (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID))
+ return err
+ })
+}
+
+// UnlinkAt implements vfs.FilesystemImpl.UnlinkAt.
+func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error {
+ return fs.unlinkAt(ctx, rp, false /* dir */)
+}
+
+// ListxattrAt implements vfs.FilesystemImpl.ListxattrAt.
+func (fs *filesystem) ListxattrAt(ctx context.Context, rp *vfs.ResolvingPath) ([]string, error) {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return nil, err
+ }
+ return d.listxattr(ctx)
+}
+
+// GetxattrAt implements vfs.FilesystemImpl.GetxattrAt.
+func (fs *filesystem) GetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) (string, error) {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return "", err
+ }
+ return d.getxattr(ctx, name)
+}
+
+// SetxattrAt implements vfs.FilesystemImpl.SetxattrAt.
+func (fs *filesystem) SetxattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetxattrOptions) error {
+ var ds *[]*dentry
+ fs.renameMu.RLock()
+ defer fs.renameMuRUnlockAndCheckCaching(&ds)
+ d, err := fs.resolveLocked(ctx, rp, &ds)
+ if err != nil {
+ return err
+ }
+ return d.setxattr(ctx, &opts)
+}
+
+// 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 {
+ return err
+ }
+ return d.removexattr(ctx, name)
+}
+
+// PrependPath implements vfs.FilesystemImpl.PrependPath.
+func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
+ fs.renameMu.RLock()
+ defer fs.renameMu.RUnlock()
+ return vfs.GenericPrependPath(vfsroot, vd, b)
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 21:29:27 +0000