From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752087Ab1IZQKY (ORCPT ); Mon, 26 Sep 2011 12:10:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3853 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751834Ab1IZQKX (ORCPT ); Mon, 26 Sep 2011 12:10:23 -0400 Date: Mon, 26 Sep 2011 18:06:19 +0200 From: Oleg Nesterov To: "Serge E. Hallyn" Cc: lkml , richard@nod.at, Andrew Morton , "Eric W. Biederman" , Tejun Heo , serge@hallyn.com Subject: Re: [PATCH] user namespace: make signal.c respect user namespaces Message-ID: <20110926160619.GA13736@redhat.com> References: <20110919214531.GA18085@sergelap> <20110920174849.GB22317@redhat.com> <20110920185354.GA19629@sergelap> <20110921175357.GA25590@redhat.com> <20110923163113.GA3820@sergelap> <20110923173656.GA5233@redhat.com> <20110923212025.GA21330@sergelap> <20110924163709.GA6776@redhat.com> <20110925201723.GA5288@sergelap> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110925201723.GA5288@sergelap> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/25, Serge E. Hallyn wrote: > > Quoting Oleg Nesterov (oleg@redhat.com): > > On 09/23, Serge E. Hallyn wrote: > > > > > > Quoting Oleg Nesterov (oleg@redhat.com): > > > > On 09/23, Serge E. Hallyn wrote: > > > > > > > > > > It looks like I can fix all the > > > > > cases > > > > > > > > except ptrace_signal(). Although we can simply ignore this case, imho. > > > > > > ptrace_signal() calls send_signal() though. > > > > Confused... I meant the "if (signr != info->si_signo)" case. This is > > simple, and I only meant that this case is not that important. > > Yes, that's the case I was talking about. That then proceeds through > send_signal(). It doesn't? I am even more confuused. Anyway, your patch adds map_cred_ns() into ptrace_signal(). > The whole new patch (so far only compile-tested) is below. Perhaps I missed something, but it looks overcomplicated. I was thinking about the (uncompiled/untested) simple patch below (it ignores ptrace_signal for clarity). And note that this way we do not need to modify do_notify_parent*() or ipc/mqueue.c:__do_notify() (your patch doesn't cover the latter). Unless I missed something of course. And we do not need to handle the SEND_SIG_NOINFO case separately. However, we still have the problems with sigqueueinfo, > > > > > by checking whether si_fromuser(info) > > > > > > > > I am not sure... sys_rt_queueinfo() is nasty. Plus we have to handle > > > > the "fromkernel" case too. May be we can ignore this too. > > > > > > sys_rt_tgsigqueueinfo() still seems to go through send_signal(). > > > > Yes. But how can you fix si_uid? We do not even know if it exists. > > Please look at siginfo/_uid, there is a union. We can't know what > > the caller of sys_rt_sigqueueinfo() puts in this location. > > But it's a union alongside the pid. Again, I do not understand... Yes, we have the same problem with if (from_ancestor_ns) q->info.si_pid = 0; This was discussed, we do not know what we can do. My point was, this change is not sigqueueinfo-friendly too. Oleg. --- x/kernel/signal.c +++ x/kernel/signal.c @@ -1019,6 +1019,27 @@ static inline int legacy_queue(struct si return (sig < SIGRTMIN) && sigismember(&signals->signal, sig); } +static inline fixup_uid(struct siginfo *info, struct task_struct *t) +{ +#ifdef CONFIG_USER_NS + if (current_user_ns() == task_cred_xxx(t, user_ns))) +#endif + return; + + if (SI_FROMKERNEL(info)) + switch (info->si_code & __SI_MASK) { + default: + return; + + case __SI_CHLD: + case __SI_MESGQ: + break; + } + + info->si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns), + current_cred(), info->si_uid); +} + static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, int group, int from_ancestor_ns) { @@ -1088,6 +1109,9 @@ static int __send_signal(int sig, struct q->info.si_pid = 0; break; } + + fixup_uid(info, t); + } else if (!is_si_special(info)) { if (sig >= SIGRTMIN && info->si_code != SI_USER) { /*