linux-kernel - Re: Setting FS_USERNS_MOUNT in btrfs_fs_type.fs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140917161214.GC20887@lenny.home.zabbo.net>
Date:	Wed, 17 Sep 2014 09:12:14 -0700
From:	Zach Brown <zab@...bo.net>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Shea Levy <shea@...alevy.com>, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Setting FS_USERNS_MOUNT in btrfs_fs_type.fs_flags

On Wed, Sep 17, 2014 at 04:54:48AM +0100, Al Viro wrote:
> On Tue, Sep 16, 2014 at 11:05:00PM -0400, Shea Levy wrote:
> > Hi all,
> > 
> > What work would be required to mark btrfs_fs_type with FS_USERNS_MOUNT
> > so that btrfs images can be mounted by unprivileged users within a user
> > namespace (along with something like [1])? I'd like to be able to create
> > disk images without having to start a VM (and --rootdir isn't flexible
> > enough because I want to make subvolumes).
> 
> Er...  Which is to say, you have an audit of btrfs code making sure that
> it can cope with arbitrary image hand-crafted by potential attacker?

It definitely can't cope. The easiest places to find bugs are the
hundreds of BUG_ON() sites, many can be triggered by on-disk structures.
The sheer volume of those makes me trust that you could find much worse
if you did a thorough audit.

- z
(fun related fact: distros automount btrfs images)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/