This is a note to let you know that I've just added the patch titled
btrfs: do not allow non subvolume root targets for snapshot
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
btrfs-do-not-allow-non-subvolume-root-targets-for-sn.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ca88e2226c46670a74dd9844fdc7834693d4dc5a
Author: Josef Bacik <josef@xxxxxxxxxxxxxx>
Date: Fri Dec 15 10:01:44 2023 -0500
btrfs: do not allow non subvolume root targets for snapshot
[ Upstream commit a8892fd71933126ebae3d60aec5918d4dceaae76 ]
Our btrfs subvolume snapshot <source> <destination> utility enforces
that <source> is the root of the subvolume, however this isn't enforced
in the kernel. Update the kernel to also enforce this limitation to
avoid problems with other users of this ioctl that don't have the
appropriate checks in place.
Reported-by: Martin Michaelis <code@xxxxxxx>
CC: stable@xxxxxxxxxxxxxxx # 4.14+
Reviewed-by: Neal Gompa <neal@xxxxxxxxx>
Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 23beabb489231..c76277ccf03b0 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1789,6 +1789,15 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
* are limited to own subvolumes only
*/
ret = -EPERM;
+ } else if (btrfs_ino(BTRFS_I(src_inode)) != BTRFS_FIRST_FREE_OBJECTID) {
+ /*
+ * Snapshots must be made with the src_inode referring
+ * to the subvolume inode, otherwise the permission
+ * checking above is useless because we may have
+ * permission on a lower directory but not the subvol
+ * itself.
+ */
+ ret = -EINVAL;
} else {
ret = btrfs_mksubvol(&file->f_path, name, namelen,
BTRFS_I(src_inode)->root,
