From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751719Ab3KKUcP (ORCPT ); Mon, 11 Nov 2013 15:32:15 -0500 Received: from terminus.zytor.com ([198.137.202.10]:48585 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751360Ab3KKUcG (ORCPT ); Mon, 11 Nov 2013 15:32:06 -0500 User-Agent: K-9 Mail for Android In-Reply-To: References: <1381450698-28710-4-git-send-email-keescook@chromium.org> <20131111182046.GA14961@gmail.com> <20131111183101.GA16051@gmail.com> <528131E7.2060509@zytor.com> <20131111200748.GB17408@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [tip:x86/kaslr] x86, kaslr: Provide randomness functions From: "H. Peter Anvin" Date: Mon, 11 Nov 2013 12:16:12 -0800 To: Kees Cook , Ingo Molnar CC: LKML , Thomas Gleixner , "H. Peter Anvin" , "linux-tip-commits@vger.kernel.org" Message-ID: <8fc0bcac-b07e-47e9-9cf8-e71e9a603c51@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org XOR and rotate is probably a good start. Kees Cook wrote: >On Mon, Nov 11, 2013 at 12:07 PM, Ingo Molnar wrote: >> >> * H. Peter Anvin wrote: >> >>> Of course, perhaps we could just hash struct boot_params as a >starting >>> point? >> >> Yeah, that would be a good first step, before trying to parse DMI or >ACPI. >> Anything that is reasonably system dependent and gives at least some >> amount of unpredicability. > >Given the very limited nature of the early boot environment, what >would you recommend for the hashing routine itself? There's nothing in >boot/ that does any kind of "real" crypto hashing. Should I just XOR >the entire contents of boot_params together? > >-Kees -- Sent from my mobile phone. Please pardon brevity and lack of formatting.