linux-kernel - Re: [PATCH 0/6] MODSIGN: Kernel module signing

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Date:	Thu, 15 Feb 2007 12:01:22 -0800 (PST)
From:	David Lang <david.lang@...italinsight.com>
To:	Roman Zippel <zippel@...ux-m68k.org>
cc:	David Howells <dhowells@...hat.com>, torvalds@...l.org,
	akpm@...l.org, herbert.xu@...hat.com, linux-kernel@...r.kernel.org,
	davej@...hat.com, arjan@...radead.org, linux-crypto@...r.kernel.org
Subject: Re: [PATCH 0/6] MODSIGN: Kernel module signing 

On Thu, 15 Feb 2007, Roman Zippel wrote:

> On Thu, 15 Feb 2007, David Howells wrote:
>
>> It is possible to protect /dev/mem and /dev/kmem or make them unavailable and
>> it is possible to protect the kernel's memory whilst it is running (provided
>> you don't have nommu or broken hardware and you don't let userspace concoct any
>> DMA request it likes) which mostly closes those other vectors I mentioned.
>> This isn't something I intended to look at with this patch.  Those are separate
>> holes.
>
> Exactly and as long as there are these holes, these patches are only
> kernel bloat. The simple verification can also be done in userspace and
> module signing offers no real security.
> What real value do these patches provide, that can't be reached via other
> means? Who else than distributions would be interested in this? Pretty
> much any use you initially mentioned can be done in simpler ways, e.g.
> anyone afraid of modules simply disables module loading completely.

this issue, and these holes keep comeing up in discussions, why can't these 
holes be closed? I seem to remember seeing patches that would remove /dev/kmem 
being sent to the list, but they weren't accepted into the kernel (and I seem to 
remember people being against the concept of removeing them, not against 
techincal details of the patches. but this was many years ago)

at one point I remember hearing that X required raw /dev/kmem, but for servers 
you don't need/want X anyway, so this is a useful option even if X doesn't get 
fixed.

David Lang
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