linux-kernel - Re: [PATCH v2] net: don't allow CAP_NET_ADMIN to load non-netdev kernel modules

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Message-ID: <20110302133835.5e267e9e@chukar>
Date:	Wed, 2 Mar 2011 13:38:35 -0700
From:	Jake Edge <jake@....net>
To:	Vasiliy Kulikov <segoon@...nwall.com>
Cc:	linux-kernel@...r.kernel.org, mjt@....msk.ru, arnd@...db.de,
	mirqus@...il.com, netdev@...r.kernel.org,
	Ben Hutchings <bhutchings@...arflare.com>,
	David Miller <davem@...emloft.net>, kuznet@....inr.ac.ru,
	pekkas@...core.fi, jmorris@...ei.org, yoshfuji@...ux-ipv6.org,
	kaber@...sh.net, eric.dumazet@...il.com, therbert@...gle.com,
	xiaosuo@...il.com, jesse@...ira.com, kees.cook@...onical.com,
	eugene@...hat.com, dan.j.rosenberg@...il.com,
	akpm@...ux-foundation.org
Subject: Re: [PATCH v2] net: don't allow CAP_NET_ADMIN to load non-netdev
 kernel modules

On Wed, 2 Mar 2011 23:18:07 +0300 Vasiliy Kulikov wrote:

> > and on systems that today use CAP_SYS_MODULE
> 
> Since Linux 2.6.32 CAP_SYS_MODULE may not load modules via "ifconfig
> gre0".  It was changed to CAP_NET_ADMIN.  So nothing is broken here.
> 
> > (or really the full set of
> > capabilities cuz they are running as root)?
> 
> As root has CAP_NET_ADMIN, the alias netdev-gre0 is tried and it
> succeeds.

(I feel like I'm beating a dead horse here, sorry if so ...)

If I have a setuid-root program today that loads ip_gre by using the
alias "gre0", and I run that program on a kernel with this change,
won't it fail because the "gre0" alias is missing?  That program
doesn't know to try "netdev-gre0". i.e. won't backward compatibility be
affected by this change?

jake

-- 
Jake Edge - LWN - jake@....net - http://lwn.net
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