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Date: Tue, 14 Apr 2015 17:16:08 -0500
From: Tyler Hicks <tyhicks@...onical.com>
To: Tavis Ormandy <taviso@...gle.com>
Cc: oss-security@...ts.openwall.com,
	Assign a CVE Identifier <cve-assign@...re.org>,
	security <security@...ntu.com>,
	St├ęphane Graber <stgraber@...ntu.com>
Subject: Re: Re: Problems in automatic crash analysis
 frameworks

On 2015-04-14 14:10:12, Tavis Ormandy wrote:
> On Tue, Apr 14, 2015 at 2:08 PM, Tavis Ormandy <taviso@...gle.com> wrote:
> > On Tue, Apr 14, 2015 at 1:35 PM, Tavis Ormandy <taviso@...gle.com> wrote:
> >> On Tue, Apr 14, 2015 at 9:02 AM, Marc Deslauriers
> >> <marc.deslauriers@...onical.com> wrote:
> >>> Hi,
> >>>
> >>> On 2015-04-14 11:55 AM, cve-assign@...re.org wrote:
> >>>> This is mostly a question for the persons who assigned CVE-2015-1318
> >>>> and CVE-2015-1862. Should these CVE assignments be interpreted to
> >>>> mean:
> >>>>
> >>>>   CVE-2015-1318 - in Apport, an unprivileged user can use a
> >>>>                   namespace-based attack because there is an execve by
> >>>>                   root after a chroot into a user-specified directory
> >>>
> >>> Yes, I assigned CVE-2015-1318 to that specific issue in Apport.
> >>>
> >>> Marc.
> >>
> >> It looks like this is the patch for Apport:
> >>
> >> http://bazaar.launchpad.net/~apport-hackers/apport/trunk/revision/2943#data/apport
> >>
> >> It's far more complicated than I expected, and not obviously correct.
> >> It could probably use some review, I'll think about it today.
> >>
> >> Tavis.
> >
> > Wait, my first thought is that it's not obvious to me that
> > /proc/net/unix is guaranteed to be newline delimited, newline is a
> > perfectly valid name in a filename, no?
> >
> >>>> import socket
> >>>> socket.socket(socket.AF_UNIX, socket.SOCK_STREAM).bind('test\ntest')
> >>>> sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
> >>>> sock.bind('/tmp/foo\nbar')
> >>>> sock.listen(1)
> >
> > $ grep -A1 foo /proc/net/unix
> > 0000000000000000: 00000002 00000000 00010000 0001 01 4772228 /tmp/foo
> > bar
> 
> And with complete control over this line, it seems like it's game over.
> 
>                 container = lxc.Container(path[-2], real_path)
> 
> I'm calling this re-broken.

I've pointed St├ęphane Graber to your analysis (and put him on cc). He's
working on a fix.

Even though it isn't clear if all of the checks added in revision 2943
can be bypassed, it is worth coming up with another approach.

Thanks!

Tyler

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