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Make kernfs.walkParentDirLocked() start path traversal from passed dentry.

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This is analogous to all other filesystem implementations and their
walkParentDirLocked() implementations. This is required because sometimes
walkParentDirLocked() is called after symlinks are followed. And the
traversal should continue from the parent of the symlink file.

PiperOrigin-RevId: 504326573
This commit is contained in:
Ayush Ranjan
2023-01-24 11:17:07 -08:00
committed by gVisor bot
parent 154695a6ff
commit 22961a9e41
1 changed files with 14 additions and 14 deletions
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pkg/sentry/fsimpl/kernfs/filesystem.go
+14 -14
View File
@@ -180,8 +180,7 @@ func (fs *Filesystem) walkExistingLocked(ctx context.Context, rp *vfs.ResolvingP
// - !rp.Done().
//
// Postconditions: Caller must call fs.processDeferredDecRefs*.
func (fs *Filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.ResolvingPath) (*Dentry, error) {
d := rp.Start().Impl().(*Dentry)
func (fs *Filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.ResolvingPath, d *Dentry) (*Dentry, error) {
for !rp.Final() {
var err error
d, _, err = fs.stepExistingLocked(ctx, rp, d)
@@ -342,7 +341,7 @@ func (fs *Filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPa
fs.mu.RLock()
defer fs.processDeferredDecRefs(ctx)
defer fs.mu.RUnlock()
d, err := fs.walkParentDirLocked(ctx, rp)
d, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*Dentry))
if err != nil {
return nil, err
}
@@ -358,7 +357,7 @@ func (fs *Filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
fs.mu.Lock()
defer fs.processDeferredDecRefs(ctx)
defer fs.mu.Unlock()
parent, err := fs.walkParentDirLocked(ctx, rp)
parent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*Dentry))
if err != nil {
return err
}
@@ -405,7 +404,7 @@ func (fs *Filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
fs.mu.Lock()
defer fs.processDeferredDecRefs(ctx)
defer fs.mu.Unlock()
parent, err := fs.walkParentDirLocked(ctx, rp)
parent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*Dentry))
if err != nil {
return err
}
@@ -442,7 +441,7 @@ func (fs *Filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
fs.mu.Lock()
defer fs.processDeferredDecRefs(ctx)
defer fs.mu.Unlock()
parent, err := fs.walkParentDirLocked(ctx, rp)
parent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*Dentry))
if err != nil {
return err
}
@@ -499,7 +498,7 @@ func (fs *Filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
// May create new file.
mustCreate := opts.Flags&linux.O_EXCL != 0
d := rp.Start().Impl().(*Dentry)
start := rp.Start().Impl().(*Dentry)
fs.mu.Lock()
unlocked := false
unlock := func() {
@@ -520,19 +519,19 @@ func (fs *Filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
if mustCreate {
return nil, linuxerr.EEXIST
}
if err := d.inode.CheckPermissions(ctx, rp.Credentials(), ats); err != nil {
if err := start.inode.CheckPermissions(ctx, rp.Credentials(), ats); err != nil {
return nil, err
}
// Open may block so we need to unlock fs.mu. IncRef d to prevent
// its destruction while fs.mu is unlocked.
d.IncRef()
start.IncRef()
unlock()
fd, err := d.inode.Open(ctx, rp, d, opts)
d.DecRef(ctx)
fd, err := start.inode.Open(ctx, rp, start, opts)
start.DecRef(ctx)
return fd, err
}
afterTrailingSymlink:
parent, err := fs.walkParentDirLocked(ctx, rp)
parent, err := fs.walkParentDirLocked(ctx, rp, start)
if err != nil {
return nil, err
}
@@ -566,6 +565,7 @@ afterTrailingSymlink:
// must be handled by the VFS layer.
return nil, err
}
start = parent
goto afterTrailingSymlink
}
if linuxerr.Equals(linuxerr.ENOENT, err) {
@@ -660,7 +660,7 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
// Resolve the destination directory first to verify that it's on this
// Mount.
dstDir, err := fs.walkParentDirLocked(ctx, rp)
dstDir, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*Dentry))
if err != nil {
return err
}
@@ -883,7 +883,7 @@ func (fs *Filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, targ
fs.mu.Lock()
defer fs.processDeferredDecRefs(ctx)
defer fs.mu.Unlock()
parent, err := fs.walkParentDirLocked(ctx, rp)
parent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*Dentry))
if err != nil {
return err
}