Date: Sun, 12 Jan 2014 18:59:21 +0100
From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Lubomir Rintel <lkundrak@v3.sk>, linux-kernel@vger.kernel.org,
        linux1394-devel@lists.sourceforge.net,
        Dave Hansen <dave.hansen@linux.intel.com>, security@kernel.org
Subject: Re: security review needed - Re: [PATCH] ohci: Turn remote DMA
 support into a module parameter
Message-ID: <20140112185921.3753b042@stein>
In-Reply-To: <20131223172021.2c8a8f48@stein>
References: <1387708462-12139-1-git-send-email-lkundrak@v3.sk>
	<20131223172021.2c8a8f48@stein>
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Sender: linux-kernel-owner@vger.kernel.org

On Dec 23 Stefan Richter wrote:
> On Dec 22 Lubomir Rintel wrote:
> > This makes it possible to debug kernel over FireWire without the need to
> > recompile it.
> > 
> > Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
> > Cc: Dave Hansen <dave.hansen@linux.intel.com>
> > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> 
> Looks good to me.  A load-time option is preferable over a compile-time
> option not only from the POV of the debugging use case, but also from the
> maintenance POV.
> 
> It weakens security in two scenarios though, AFAICS:
> 
> A)
>   - There are firewire-ohci and firewire-sbp2 installed on the machine,
>   - the attacker cannot upload code
>   - but can load kernel modules
>   - and has physical access to a 1394 port
>   - and is not able to run a minimal SBP-2 target on the remote 1394 end.
> 
> B)
>   - There is firewire-ohci but not firewire-sbp2 installed on the machine,
>   - the attacker cannot upload code
>   - but can load kernel modules
>   - and has physical access to a 1394 port.
> 
> (In both scenarios, the attacker additionally has to be able to /un/load
> kernel modules if firewire-ohci was loaded already before the attack.)
> 
> That's both quite specific.  Hence the security impact of this patch is
> negligible in my opinion.  Any other opinions or insights into it?

Since there were no objections, I committed it to linux1394.git master
and for-next now.
-- 
Stefan Richter
-=====-====- ---= -==--
http://arcgraph.de/sr/
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