linux-kernel - Re: [lxc-devel] Kernel bug? Setuid apps and user namespaces

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: <20140402173248.GA22804@mail.hallyn.com>
Date:	Wed, 2 Apr 2014 19:32:49 +0200
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	Serge Hallyn <serge.hallyn@...ntu.com>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Sean Pajot <sean.pajot@...culink.com>,
	lxc-devel@...ts.linuxcontainers.org, linux-kernel@...r.kernel.org
Subject: Re: [lxc-devel] Kernel bug? Setuid apps and user namespaces

(Sorry - the lxc-devel list has moved, so replying to all with the
correct list address;   please reply to this rather than my previous
email)

Quoting Serge Hallyn (serge.hallyn@...ntu.com):
> Hi Eric,
> 
> (sorry, I don't seem to have the email I actually wanted to reply
> to in my mbox, but it is
> https://lists.linuxcontainers.org/pipermail/lxc-devel/2013-October/005857.html)
> 
> You'd said,
> > Someone needs to read and think through all of the corner cases and see
> > if we can ever have a time when task_dumpable is false but root in the
> > container would not or should not be able to see everything.
> > 
> > In particular I am worried about the case of a setuid app calling setns,
> > and entering a lesser privileged user namespace.  In my foggy mind that
> > might be a security problem.  And there might be other similar crazy
> > cases.
> 
> Can we make use of current->mm->exe_file->f_cred->user_ns?
> 
> So either always use 
> make_kgid(current->mm->exe_file->f_cred->user_ns, 0)
> instead of make_kuid(cred->user_ns, 0), or check that
> (current->mm->exe_file->f_cred->user_ns == cred->user_ns)
> and, if not, assume that the caller has done a setns?
> 
> -serge
> --
> 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/
--
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/