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

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Date:	Fri, 25 Feb 2011 20:47:51 +0300
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	Valdis.Kletnieks@...edu
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	"Pekka Savola (ipv6)" <pekkas@...core.fi>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Tom Herbert <therbert@...gle.com>,
	Changli Gao <xiaosuo@...il.com>, Jesse Gross <jesse@...ira.com>
Subject: Re: [PATCH] don't allow CAP_NET_ADMIN to load non-netdev kernel
 modules

On Fri, Feb 25, 2011 at 12:25 -0500, Valdis.Kletnieks@...edu wrote:
> And you stop an attacker from simply recompiling the module with a suitable
> MODULE_ALIAS line added, how, exactly?  This patch may make sense down the
> road, but not while it's still trivial for a malicious root user to drop stuff
> into /lib/modules.

The threat is not a malicious root, but non-root with CAP_NET_ADMIN.
It's hardly possible to load arbitrary module into the kernel having
CAP_NET_ADMIN without other capabilities.

> And if you're going the route "but SELinux/SMACK/Tomoyo will prevent a malicious
> root user from doing that", then the obvious reply is "this should be part of those
> subsystems rather than something done one-off like this (especially as it has a chance
> of breaking legitimate setups that use the current scheme).

No, I don't want to add anything about LSMs at all.


Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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