| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.12 131/133] btrfs: restrict snapshotting to own subvolumes | Date | Tue, 4 Feb 2014 13:08:52 -0800 |
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3.12-stable review patch. If anyone has any objections, please let me know.
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From: David Sterba <dsterba@suse.cz>
commit d024206133ce21936b3d5780359afc00247655b7 upstream.
Currently, any user can snapshot any subvolume if the path is accessible and thus indirectly create and keep files he does not own under his direcotries. This is not possible with traditional directories.
In security context, a user can snapshot root filesystem and pin any potentially buggy binaries, even if the updates are applied.
All the snapshots are visible to the administrator, so it's possible to verify if there are suspicious snapshots.
Another more practical problem is that any user can pin the space used by eg. root and cause ENOSPC.
Original report: https://bugs.launchpad.net/ubuntu/+source/apparmor/+bug/484786
Signed-off-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/btrfs/ioctl.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1548,6 +1548,12 @@ static noinline int btrfs_ioctl_snap_cre printk(KERN_INFO "btrfs: Snapshot src from " "another FS\n"); ret = -EINVAL; + } else if (!inode_owner_or_capable(src_inode)) { + /* + * Subvolume creation is not restricted, but snapshots + * are limited to own subvolumes only + */ + ret = -EPERM; } else { ret = btrfs_mksubvol(&file->f_path, name, namelen, BTRFS_I(src_inode)->root,
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