linux-kernel - Re: [PATCH] user namespace: make signal.c respect user namespaces

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Date:	Sat, 24 Sep 2011 18:37:09 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	"Serge E. Hallyn" <serge.hallyn@...onical.com>
Cc:	lkml <linux-kernel@...r.kernel.org>, richard@....at,
	Andrew Morton <akpm@...gle.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Tejun Heo <tj@...nel.org>, serge@...lyn.com
Subject: Re: [PATCH] user namespace: make signal.c respect user namespaces

On 09/23, Serge E. Hallyn wrote:
>
> Quoting Oleg Nesterov (oleg@...hat.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.

> > > 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.

Oleg.

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