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

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Message-ID: <20110527184358.GA19633@outflux.net>
Date:	Fri, 27 May 2011 11:43:58 -0700
From:	Kees Cook <kees.cook@...onical.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dan Rosenberg <drosenberg@...curity.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Tony Luck <tony.luck@...il.com>,
	linux-kernel@...r.kernel.org, davej@...hat.com,
	davem@...emloft.net, eranian@...gle.com, adobriyan@...il.com,
	penberg@...nel.org, hpa@...or.com,
	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 Fri, May 27, 2011 at 08:17:24PM +0200, Ingo Molnar wrote:
>  - Boot time dynamic randomization allows randomization of 'mass 
>    install' systems, where the same image is used, to still be 
>    randomized: for example a million phones all with the same Flash 
>    ROM image and no 'install' performed at all on them.
> 
>    With static randomization these systems will all have the same
>    kernel addresses.
> 
>  - Boot time dynamic randomization allows read-only systems to still 
>    be randomized: for example internet cafes that use some popular 
>    pre-packaged kiosk-mode live-DVD. They probably wont bother 
>    randomizing and relinking the ISOs per machine and burning per 
>    machine DVDs ...

These 2 points are pretty significant, IMO.

And frankly, distros almost fall into these categories already. IIUC,
a distro would need to ship all of the .o files from each config of the
kernel they ship so each system could do the relinking. That's not a
small foot print to suddenly add to base installs.

-Kees

-- 
Kees Cook
Ubuntu Security Team
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