From cc5eec86a4ffeaeb7ed88c291d59eac359d30437 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 [ Upstream commit a8892fd71933126ebae3d60aec5918d4dceaae76 ] 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: Sasha Levin --- fs/btrfs/ioctl.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 6da8587e2ae3..f06824bea468 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1868,6 +1868,15 @@ 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, name, namelen, BTRFS_I(src_inode)->root,