linux-kernel - Re: [RFC][PATCH] Randomize kernel base address on boot

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Message-ID: <4DDFDA22.205@zytor.com>
Date:	Fri, 27 May 2011 10:06:42 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Dan Rosenberg <drosenberg@...curity.com>,
	Tony Luck <tony.luck@...il.com>, linux-kernel@...r.kernel.org,
	davej@...hat.com, kees.cook@...onical.com, davem@...emloft.net,
	eranian@...gle.com, adobriyan@...il.com, penberg@...nel.org,
	Arjan van de Ven <arjan@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Valdis.Kletnieks@...edu, pageexec@...email.hu
Subject: Re: [RFC][PATCH] Randomize kernel base address on boot

On 05/27/2011 10:00 AM, Ingo Molnar wrote:
> 
> The problem with your relinking solution is that a local attacker can 
> easily figure out where the kernel is. So this does not protect 
> against the more common break-in scenario.
> 

There is another issue with it: it doesn't actually solve the real
problem other than suspend/resume, which is that the relocation agent
needs to understand what the memory space looks like at the time of boot.

I think something else we will need for this to be possible is initramfs
decoding directly from highmem, since the hack we're currently using to
deal with an initramfs/initrd located partly in highmem will break.

	-hpa
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