From 56f762659a5e9fde8220a88e19fd5ec4b12eda6d Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 15 Dec 2023 10:01:44 -0500 Subject: [PATCH] btrfs: do not allow non subvolume root targets for snapshot commit a8892fd71933126ebae3d60aec5918d4dceaae76 upstream. Our btrfs subvolume snapshot utility enforces that 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 CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Neal Gompa Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/ioctl.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index dc6e3cce747c..e8e4781c48a5 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2182,6 +2182,15 @@ static noinline int __btrfs_ioctl_snap_create(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_mksnapshot(&file->f_path, mnt_userns, name, namelen,