This is a note to let you know that I've just added the patch titled
btrfs: restrict snapshotting to own subvolumes
to the 3.12-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-restrict-snapshotting-to-own-subvolumes.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d024206133ce21936b3d5780359afc00247655b7 Mon Sep 17 00:00:00 2001
From: David Sterba <dsterba@xxxxxxx>
Date: Wed, 15 Jan 2014 18:15:52 +0100
Subject: btrfs: restrict snapshotting to own subvolumes
From: David Sterba <dsterba@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Josef Bacik <jbacik@xxxxxx>
Signed-off-by: Chris Mason <clm@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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,
Patches currently in stable-queue which might be from dsterba@xxxxxxx are
queue-3.12/btrfs-restrict-snapshotting-to-own-subvolumes.patch
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