linux-kernel - Re: [PATCH 2/2] sysctl: allow CLONE

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Date:	Fri, 22 Jan 2016 15:00:38 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Robert Święcki <robert@...ecki.net>,
	"Serge E. Hallyn" <serge.hallyn@...ntu.com>,
	Ben Hutchings <ben@...adent.org.uk>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Richard Weinberger <richard@....at>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andy Lutomirski <luto@...capital.net>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	David Howells <dhowells@...hat.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH 2/2] sysctl: allow CLONE_NEWUSER to be disabled

On Fri, Jan 22, 2016 at 2:55 PM, Robert Święcki <robert@...ecki.net> wrote:
> 2016-01-22 23:50 GMT+01:00 Kees Cook <keescook@...omium.org>:
>
>>> Seems that Debian and some older Ubuntu versions are already using
>>>
>>> $ sysctl -a | grep usern
>>> kernel.unprivileged_userns_clone = 0
>>>
>>> Shall we be consistent wit it?
>>
>> Oh! I didn't see that on systems I checked. On which version did you find that?
>
> $ uname -a
> Linux bc1 4.3.0-0.bpo.1-amd64 #1 SMP Debian 4.3.3-5~bpo8+1
> (2016-01-07) x86_64 GNU/Linux
> $ cat /etc/debian_version
> 8.2

Ah-ha, Debian only, though it looks like this was just committed to
the Ubuntu kernel tree too:


> IIRC some older kernels delivered with Ubuntu Precise were also using
> it (but maybe I'm mistaken)

I don't see it there.

I think my patch is more complete, but I'm happy to change the name if
this sysctl has already started to enter the global consciousness. ;)

Serge, Ben, what do you think?

-Kees


-- 
Kees Cook
Chrome OS & Brillo Security