Implement setxattr for overlays.

PiperOrigin-RevId: 290186303

3 files changed, 13 insertions, 6 deletions

diff --git a/pkg/sentry/fs/inode.go b/pkg/sentry/fs/inode.go
index ee9d301ef..e4cf5a570 100644
--- a/pkg/sentry/fs/inode.go
+++ b/pkg/sentry/fs/inode.go
@@ -270,9 +270,9 @@ func (i *Inode) GetXattr(ctx context.Context, name string, size uint64) (string,
 }
 
 // SetXattr calls i.InodeOperations.SetXattr with i as the Inode.
-func (i *Inode) SetXattr(ctx context.Context, name, value string, flags uint32) error {
+func (i *Inode) SetXattr(ctx context.Context, d *Dirent, name, value string, flags uint32) error {
 	if i.overlay != nil {
-		return overlaySetxattr(ctx, i.overlay, name, value, flags)
+		return overlaySetxattr(ctx, i.overlay, d, name, value, flags)
 	}
 	return i.InodeOperations.SetXattr(ctx, i, name, value, flags)
 }
diff --git a/pkg/sentry/fs/inode_overlay.go b/pkg/sentry/fs/inode_overlay.go
index b90da20d0..c477de837 100644
--- a/pkg/sentry/fs/inode_overlay.go
+++ b/pkg/sentry/fs/inode_overlay.go
@@ -552,9 +552,16 @@ func overlayGetXattr(ctx context.Context, o *overlayEntry, name string, size uin
 	return s, err
 }
 
-// TODO(b/146028302): Support setxattr for overlayfs.
-func overlaySetxattr(ctx context.Context, o *overlayEntry, name, value string, flags uint32) error {
-	return syserror.EOPNOTSUPP
+func overlaySetxattr(ctx context.Context, o *overlayEntry, d *Dirent, name, value string, flags uint32) error {
+	// Don't allow changes to overlay xattrs through a setxattr syscall.
+	if strings.HasPrefix(XattrOverlayPrefix, name) {
+		return syserror.EPERM
+	}
+
+	if err := copyUp(ctx, d); err != nil {
+		return err
+	}
+	return o.upper.SetXattr(ctx, d, name, value, flags)
 }
 
 func overlayListXattr(ctx context.Context, o *overlayEntry) (map[string]struct{}, error) {
diff --git a/pkg/sentry/syscalls/linux/sys_xattr.go b/pkg/sentry/syscalls/linux/sys_xattr.go
index 816352218..23d20da6f 100644
--- a/pkg/sentry/syscalls/linux/sys_xattr.go
+++ b/pkg/sentry/syscalls/linux/sys_xattr.go
@@ -142,7 +142,7 @@ func setXattr(t *kernel.Task, d *fs.Dirent, dirPath bool, nameAddr, valueAddr us
 		return syserror.EOPNOTSUPP
 	}
 
-	return d.Inode.SetXattr(t, name, value, flags)
+	return d.Inode.SetXattr(t, d, name, value, flags)
 }
 
 func copyInXattrName(t *kernel.Task, nameAddr usermem.Addr) (string, error) {