[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 5 Apr 2013 10:04:18 +0200
From: Ingo Molnar <mingo@...nel.org>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
Jarkko Sakkinen <jarkko.sakkinen@...el.com>,
Matthew Garrett <mjg@...hat.com>,
Matt Fleming <matt.fleming@...el.com>,
Eric Northup <digitaleric@...gle.com>,
Dan Rosenberg <drosenberg@...curity.com>,
Julien Tinnes <jln@...gle.com>, Will Drewry <wad@...omium.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 3/3] x86: kernel base offset ASLR
* H. Peter Anvin <hpa@...or.com> wrote:
> I have to admit to being somewhat skeptical toward KASLR with only 8
> bits of randomness. There are at least two potential ways of
> dramatically increasing the available randomness:
>
> 1. actually compose the kernel of multiple independently relocatable
> pieces (maybe chunk it on 2M boundaries or something.)
>
> 2. compile the kernel as one of the memory models which can be executed
> anywhere in the 64-bit address space. The cost of this would have
> to be quantified, of course.
>
> The latter is particularly something that should be considered for the
> LPF JIT, to defend against JIT spray attacks.
The cost of 64-bit RIPs is probably measurable both in cache footprint and
in execution speed.
Doing that might make sense - but unless it's surprisingly cheap to do it,
at least from a distro perspective, randomizing the kernel base using the
existing compact address space would probably be the preferred option -
even if a bigger build model was available.
Random runtime shuffling of the kernel image - is that possible with
existing toolchains?
Thanks,
Ingo
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
