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Date: Mon, 18 Mar 2013 16:36:40 +0100
From: Agostino Sarubbo <ago@...too.org>
To: oss-security@...ts.openwall.com
Subject: Re: CLONE_NEWUSER|CLONE_FS root exploit
On Wednesday 13 March 2013 18:33:00 Greg KH wrote:
> On Thu, Mar 14, 2013 at 09:03:20AM +0800, Eugene Teo wrote:
> > On 14 Mar, 2013, at 8:59 AM, Eugene Teo <eugeneteo@...nel.sg> wrote:
> > > On 13 Mar, 2013, at 11:39 PM, Sebastian Krahmer <krahmer@...e.de> wrote:
> > >> Hi,
> > >>
> > >> Seems like CLONE_NEWUSER|CLONE_FS might be a forbidden
> > >> combination.
> > >> During evaluating the new user namespace thingie, it turned out
> > >> that its trivially exploitable to get a (real) uid 0,
> > >> as demonstrated here:
> > >>
> > >> http://stealth.openwall.net/xSports/clown-newuser.c
> > >>
> > >> The trick is to setup a chroot in your CLONE_NEWUSER,
> > >> but also affecting the parent, which is running
> > >> in the init_user_ns, but with the chroot shared.
> > >> Then its trivial to get a rootshell from that.
> > >>
> > >> Tested on a openSUSE12.1 with a custom build 3.8.2 (x86_64).
> > >>
> > >> I hope I didnt make anything wrong, mixing up the UIDs,
> > >> or disabled important checks during kernel build on my test
> > >> system. ;)
> > >
> > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?
> > > id=aea8b5d1e5c5482e7cdda849dc16d728f7080289>
> > I realised that the link is incorrect. Will post again when I see the
> > patches.
> It is commit e66eded8309ebf679d3d3c1f5820d1f2ca332c71 in Linus's tree,
> so replace the sha in the above link with this one instead.
Someone know exactly in which version the bug appears and which series are
affected?
--
Agostino Sarubbo
Gentoo Linux Developer
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