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

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Date:	Tue, 20 Sep 2011 20:17:51 +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 09/20, Serge E. Hallyn wrote:
>
> Quoting Oleg Nesterov (oleg@...hat.com):
> >
> > I didn't really check, but afaics send_sigio_to_task/etc never use
> > SEND_SIG_NOINFO. And they shouldn't, there is no the sending process.
>
> (I'm sure you're right -

I am not that sure, please recheck ;)

> > I guess ptrace_signal() can even do
> >
> > 	info->si_pid = task_pid_vnr(current->parent);
> >
> > 	if (info->si_pid)	// same namespace
> > 		info->si_uid = current_uid();
> > 	else			// can't see the tracer, we are from the sub-namespace
> > 		info->si_uid = 0;
> >
> > Whatever you like more.
>
> Except you don't have to split pid and user namespaces at the same
> time.

Argh, you mean CLONE_NEWUSER? I fotgot about it. And probably
there is something else which I simply do not know?

I got lost. This means send_signal() can't rely on from_parent_ns.
I have no idea how can we fix sys_kill() without a lot of ugly changes
then.

Oleg.

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