From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Subject: Re: [PATCH 1/6] user namespace: make signal.c respect user
	namespaces (v4)
Date: Tue, 8 Nov 2011 16:22:16 -0800
Message-ID: <20111108162216.1ffb3e9a.akpm@linux-foundation.org>
References: <1320445482-8459-1-git-send-email-serge@hallyn.com>
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To: Serge Hallyn <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
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List-Id: containers.vger.kernel.org

On Fri,  4 Nov 2011 22:24:37 +0000
Serge Hallyn <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org> wrote:

> +static inline void 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))
> +		return;
> +
> +	info->si_uid = user_ns_map_uid(task_cred_xxx(t, user_ns),
> +					current_cred(), info->si_uid);
> +}

err, this function is a no-op if CONFIG_USER_NS=n.  If that was
intentional then why on earth do this in such a weird fashion?  If
unintentional then it makes me wonder how well tested all this was with
CONFIG_USER_NS=n?

I vaguely remember that I've forgotten how all this stuff works.  Some
additional review input would be nice (cough-oleg-cough).