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Unconditionally check for directory-ness in overlay.filesystem.UnlinkAt(). 

PiperOrigin-RevId: 357106080
This commit is contained in:
Jamie Liu 2021-02-11 19:08:18 -08:00 committed by gVisor bot
parent 91cf7b3ca4
commit 34614c3986
1 changed files with 19 additions and 45 deletions
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40
pkg/sentry/fsimpl/overlay/filesystem.go
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@ -1308,8 +1308,8 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
return err
}
// Unlike UnlinkAt, we need a dentry representing the child directory being
// removed in order to verify that it's empty.
// We need a dentry representing the child directory being removed in order
// to verify that it's empty.
child, _, err := fs.getChildLocked(ctx, parent, name, &ds)
if err != nil {
return err
@ -1555,50 +1555,24 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
return err
}
parentMode := atomic.LoadUint32(&parent.mode)
child := parent.children[name]
var childLayer lookupLayer
if child == nil {
if parentMode&linux.S_ISVTX != 0 {
// If the parent's sticky bit is set, we need a child dentry to get
// its owner.
child, _, err = fs.getChildLocked(ctx, parent, name, &ds)
// We need a dentry representing the child being removed in order to verify
// that it's not a directory.
child, childLayer, err := fs.getChildLocked(ctx, parent, name, &ds)
if err != nil {
return err
}
} else {
// Determine if the file being unlinked actually exists. Holding
// parent.dirMu prevents a dentry from being instantiated for the file,
// which in turn prevents it from being copied-up, so this result is
// stable.
childLayer, err = fs.lookupLayerLocked(ctx, parent, name)
if err != nil {
return err
}
if !childLayer.existsInOverlay() {
return syserror.ENOENT
}
}
}
if child != nil {
if child.isDir() {
return syserror.EISDIR
}
if err := parent.mayDelete(rp.Credentials(), child); err != nil {
return err
}
if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
return err
}
// Hold child.copyMu to prevent it from being copied-up during
// deletion.
child.copyMu.RLock()
defer child.copyMu.RUnlock()
if child.upperVD.Ok() {
childLayer = lookupLayerUpper
} else {
childLayer = lookupLayerLower
}
if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
return err
}
pop := vfs.PathOperation{