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

Kees Cook
2011-05-27T18:44:48Z

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