From: Vasiliy Kulikov <segoon@openwall.com>
To: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Pavel Emelyanov <xemul@parallels.com>,
Andrey Vagin <avagin@openvz.org>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Glauber Costa <glommer@parallels.com>,
Andi Kleen <andi@firstfloor.org>, Tejun Heo <tj@kernel.org>,
Matt Helsley <matthltc@us.ibm.com>,
Pekka Enberg <penberg@kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Valdis.Kletnieks@vt.edu, Michal Marek <mmarek@suse.cz>,
Frederic Weisbecker <fweisbec@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree
Date: Wed, 15 Feb 2012 23:57:33 +0400 [thread overview]
Message-ID: <20120215195733.GA8021@albatros> (raw)
In-Reply-To: <20120215195610.GJ4533@moon>
On Wed, Feb 15, 2012 at 23:56 +0400, Cyrill Gorcunov wrote:
> On Wed, Feb 15, 2012 at 07:43:36PM +0100, Oleg Nesterov wrote:
> ...
> >
> > Cough... this is question I am trying to ask ;)
> >
> > Let me try again. To simplify, lets discuss the KCMP_VM case
> > only.
> >
> > I do not really understand why do we need ptrace_may_access().
> > I do not see any security problems with kcmp_ptr(task->mm), but
> > I am not expert.
> >
> > However, you added this check so I assume you have some reason.
> > But this can race with execve(setuid_app) and KCMP_VM can play
> > with task->mm after this task raises its caps. If this is fine,
> > then why do we need ptrace_may_access?
> >
>
> This makes me scratch the head ;) I think ptrace_may_access (or
> some other security test) should remain since it's somehow weird
> if non-root task will be able to find objects order from privileged
> task. Thus I need to find a way how to handle execve(setuid_app).
> Need to think...
Look at fs/proc/base.c:lock_trace() - it locks ->cred_guard_mutex
for the whole period of time when it uses a resource.
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
next prev parent reply other threads:[~2012-02-15 20:02 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-15 14:36 + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree Oleg Nesterov
2012-02-15 15:10 ` Cyrill Gorcunov
2012-02-15 15:38 ` Oleg Nesterov
2012-02-15 16:13 ` Cyrill Gorcunov
2012-02-15 16:22 ` Oleg Nesterov
2012-02-15 17:53 ` Cyrill Gorcunov
2012-02-15 18:43 ` Oleg Nesterov
2012-02-15 19:56 ` Cyrill Gorcunov
2012-02-15 19:57 ` Vasiliy Kulikov [this message]
2012-02-15 20:05 ` Cyrill Gorcunov
2012-02-15 20:25 ` Cyrill Gorcunov
2012-02-15 21:09 ` Cyrill Gorcunov
2012-02-15 21:58 ` Cyrill Gorcunov
2012-02-16 14:49 ` Oleg Nesterov
2012-02-16 15:13 ` Cyrill Gorcunov
2012-02-16 16:49 ` Cyrill Gorcunov
2012-02-16 17:40 ` Oleg Nesterov
2012-02-16 17:58 ` Cyrill Gorcunov
2012-02-16 19:03 ` Oleg Nesterov
2012-02-16 19:20 ` H. Peter Anvin
2012-02-16 19:29 ` Cyrill Gorcunov
2012-02-16 19:52 ` Andrew Morton
2012-02-16 20:01 ` Cyrill Gorcunov
2012-02-16 18:21 ` Vasiliy Kulikov
2012-02-16 18:34 ` Cyrill Gorcunov
2012-02-16 18:33 ` Vasiliy Kulikov
2012-02-16 18:49 ` Oleg Nesterov
2012-02-15 18:32 ` Cyrill Gorcunov
2012-02-15 19:06 ` Oleg Nesterov
2012-02-15 19:18 ` Cyrill Gorcunov
2012-02-15 16:06 ` Oleg Nesterov
2012-02-15 16:27 ` Cyrill Gorcunov
2012-04-09 22:10 ` Andrew Morton
2012-04-09 22:24 ` Cyrill Gorcunov
2012-04-09 23:22 ` H. Peter Anvin
2012-04-10 22:37 ` Cyrill Gorcunov
2012-04-10 22:39 ` H. Peter Anvin
2012-04-10 22:48 ` Cyrill Gorcunov
2012-04-10 23:08 ` Oleg Nesterov
2012-04-10 23:32 ` H. Peter Anvin
2012-04-10 23:42 ` Oleg Nesterov
2012-04-11 6:39 ` Cyrill Gorcunov
2012-04-11 18:31 ` Oleg Nesterov
2012-04-11 0:02 ` Valdis.Kletnieks
2012-04-10 3:25 ` Eric W. Biederman
2012-04-10 22:54 ` Cyrill Gorcunov
2012-04-10 23:58 ` Valdis.Kletnieks
2012-04-11 0:06 ` H. Peter Anvin
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