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Diffstat (limited to 'pkg/sentry/fs/inode_overlay.go')
-rw-r--r--pkg/sentry/fs/inode_overlay.go101
1 files changed, 63 insertions, 38 deletions
diff --git a/pkg/sentry/fs/inode_overlay.go b/pkg/sentry/fs/inode_overlay.go
index 92a77917a..6e1dfecf9 100644
--- a/pkg/sentry/fs/inode_overlay.go
+++ b/pkg/sentry/fs/inode_overlay.go
@@ -44,7 +44,11 @@ func overlayWriteOut(ctx context.Context, o *overlayEntry) error {
return err
}
-func overlayLookup(ctx context.Context, parent *overlayEntry, inode *Inode, name string) (*Dirent, error) {
+// overlayLookup performs a lookup in parent.
+//
+// If name exists, it returns true if the Dirent is in the upper, false if the
+// Dirent is in the lower.
+func overlayLookup(ctx context.Context, parent *overlayEntry, inode *Inode, name string) (*Dirent, bool, error) {
// Hot path. Avoid defers.
parent.copyMu.RLock()
@@ -71,7 +75,7 @@ func overlayLookup(ctx context.Context, parent *overlayEntry, inode *Inode, name
// We encountered an error that an overlay cannot handle,
// we must propagate it to the caller.
parent.copyMu.RUnlock()
- return nil, err
+ return nil, false, err
}
if child != nil {
if child.IsNegative() {
@@ -93,23 +97,23 @@ func overlayLookup(ctx context.Context, parent *overlayEntry, inode *Inode, name
// that negative Dirent being cached in
// the Dirent tree, so we can return
// one from the overlay.
- return NewNegativeDirent(name), nil
+ return NewNegativeDirent(name), false, nil
}
// Upper fs is not OK with a negative Dirent
// being cached in the Dirent tree, so don't
// return one.
- return nil, syserror.ENOENT
+ return nil, false, syserror.ENOENT
}
entry, err := newOverlayEntry(ctx, upperInode, nil, false)
if err != nil {
// Don't leak resources.
upperInode.DecRef()
parent.copyMu.RUnlock()
- return nil, err
+ return nil, false, err
}
d, err := NewDirent(newOverlayInode(ctx, entry, inode.MountSource), name), nil
parent.copyMu.RUnlock()
- return d, err
+ return d, true, err
}
}
@@ -127,7 +131,7 @@ func overlayLookup(ctx context.Context, parent *overlayEntry, inode *Inode, name
upperInode.DecRef()
}
parent.copyMu.RUnlock()
- return nil, err
+ return nil, false, err
}
if child != nil {
if !child.IsNegative() {
@@ -158,9 +162,9 @@ func overlayLookup(ctx context.Context, parent *overlayEntry, inode *Inode, name
// one as well. See comments above regarding negativeUpperChild
// for more info.
if negativeUpperChild {
- return NewNegativeDirent(name), nil
+ return NewNegativeDirent(name), false, nil
}
- return nil, syserror.ENOENT
+ return nil, false, syserror.ENOENT
}
// Did we find a lower Inode? Remember this because we may decide we don't
@@ -195,11 +199,11 @@ func overlayLookup(ctx context.Context, parent *overlayEntry, inode *Inode, name
lowerInode.DecRef()
}
parent.copyMu.RUnlock()
- return nil, err
+ return nil, false, err
}
d, err := NewDirent(newOverlayInode(ctx, entry, inode.MountSource), name), nil
parent.copyMu.RUnlock()
- return d, err
+ return d, upperInode != nil, err
}
func overlayCreate(ctx context.Context, o *overlayEntry, parent *Dirent, name string, flags FileFlags, perm FilePermissions) (*File, error) {
@@ -317,7 +321,7 @@ func overlayRemove(ctx context.Context, o *overlayEntry, parent *Dirent, child *
return nil
}
-func overlayRename(ctx context.Context, o *overlayEntry, oldParent *Dirent, renamed *Dirent, newParent *Dirent, newName string) error {
+func overlayRename(ctx context.Context, o *overlayEntry, oldParent *Dirent, renamed *Dirent, newParent *Dirent, newName string, replacement bool) error {
// To be able to copy these up below, they have to be part of an
// overlay file system.
//
@@ -327,36 +331,57 @@ func overlayRename(ctx context.Context, o *overlayEntry, oldParent *Dirent, rena
return syserror.EXDEV
}
- // Check here if the file to be replaced exists and is a non-empty
- // directory. If we copy up first, we may end up copying the directory
- // but none of its children, so the directory will appear empty in the
- // upper fs, which will then allow the rename to proceed when it should
- // return ENOTEMPTY.
- replaced, err := newParent.Inode.Lookup(ctx, newName)
- if err != nil && err != syserror.ENOENT {
- return err
- }
- if err == nil {
- // NOTE: We must drop the reference on replaced before we make
- // the rename call. For that reason we can't use defer.
- if !replaced.IsNegative() && IsDir(replaced.Inode.StableAttr) {
- children, err := readdirOne(ctx, replaced)
- if err != nil {
- replaced.DecRef()
- return err
+ if replacement {
+ // Check here if the file to be replaced exists and is a
+ // non-empty directory. If we copy up first, we may end up
+ // copying the directory but none of its children, so the
+ // directory will appear empty in the upper fs, which will then
+ // allow the rename to proceed when it should return ENOTEMPTY.
+ //
+ // NOTE: Ideally, we'd just pass in the replaced
+ // Dirent from Rename, but we must drop the reference on
+ // replaced before we make the rename call, so Rename can't
+ // pass the Dirent to the Inode without significantly
+ // complicating the API. Thus we look it up again here.
+ //
+ // For the same reason we can't use defer here.
+ replaced, inUpper, err := overlayLookup(ctx, newParent.Inode.overlay, newParent.Inode, newName)
+ // If err == ENOENT or a negative Dirent is returned, then
+ // newName has been removed out from under us. That's fine;
+ // filesystems where that can happen must handle stale
+ // 'replaced'.
+ if err != nil && err != syserror.ENOENT {
+ return err
+ }
+ if err == nil {
+ if !inUpper {
+ // newName doesn't exist in
+ // newParent.Inode.overlay.upper, thus from
+ // that Inode's perspective this won't be a
+ // replacing rename.
+ replacement = false
}
- // readdirOne ensures that "." and ".." are not
- // included among the returned children, so we don't
- // need to bother checking for them.
- if len(children) > 0 {
- replaced.DecRef()
- return syserror.ENOTEMPTY
+ if !replaced.IsNegative() && IsDir(replaced.Inode.StableAttr) {
+ children, err := readdirOne(ctx, replaced)
+ if err != nil {
+ replaced.DecRef()
+ return err
+ }
+
+ // readdirOne ensures that "." and ".." are not
+ // included among the returned children, so we don't
+ // need to bother checking for them.
+ if len(children) > 0 {
+ replaced.DecRef()
+ return syserror.ENOTEMPTY
+ }
}
- }
- replaced.DecRef()
+ replaced.DecRef()
+ }
}
+
if err := copyUpLockedForRename(ctx, renamed); err != nil {
return err
}
@@ -364,7 +389,7 @@ func overlayRename(ctx context.Context, o *overlayEntry, oldParent *Dirent, rena
return err
}
oldName := renamed.name
- if err := o.upper.InodeOperations.Rename(ctx, oldParent.Inode.overlay.upper, oldName, newParent.Inode.overlay.upper, newName); err != nil {
+ if err := o.upper.InodeOperations.Rename(ctx, oldParent.Inode.overlay.upper, oldName, newParent.Inode.overlay.upper, newName, replacement); err != nil {
return err
}
if renamed.Inode.overlay.lowerExists {
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-02 02:30:56 +0000