5.15-stable review patch. If anyone has any objections, please let me know.
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From: Josef Bacik josef@toxicpanda.com
commit a8892fd71933126ebae3d60aec5918d4dceaae76 upstream.
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@mgjm.de CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Neal Gompa neal@gompa.dev Signed-off-by: Josef Bacik josef@toxicpanda.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/ioctl.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1855,6 +1855,15 @@ static noinline int __btrfs_ioctl_snap_c * 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_mksnapshot(&file->f_path, mnt_userns, name, namelen,