Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764848Ab3DDU2a (ORCPT ); Thu, 4 Apr 2013 16:28:30 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57422 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764829Ab3DDU22 (ORCPT ); Thu, 4 Apr 2013 16:28:28 -0400 Message-ID: <515DE24D.3080507@zytor.com> Date: Thu, 04 Apr 2013 13:27:57 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: Julien Tinnes CC: Kees Cook , linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, Thomas Gleixner , Ingo Molnar , x86@kernel.org, Jarkko Sakkinen , Matthew Garrett , Matt Fleming , Eric Northup , Dan Rosenberg , Will Drewry Subject: Re: [PATCH 3/3] x86: kernel base offset ASLR References: <1365106055-22939-1-git-send-email-keescook@chromium.org> <1365106055-22939-4-git-send-email-keescook@chromium.org> <515DDEC0.9000109@zytor.com> In-Reply-To: X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1297 Lines: 34 On 04/04/2013 01:23 PM, Julien Tinnes wrote: > On Thu, Apr 4, 2013 at 1:19 PM, Julien Tinnes wrote: >> On Thu, Apr 4, 2013 at 1:12 PM, H. Peter Anvin wrote: >>> On 04/04/2013 01:07 PM, Kees Cook wrote: >>>> However, the benefits of >>>> this feature in certain environments exceed the perceived weaknesses[2]. >>> >>> Could you clarify? >> >> I think privilege reduction in general, and sandboxing in particular, >> can make KASLR even more useful. A lot of the information leaks can be >> mitigated in the same way as attack surface and vulnerabilities can be >> mitigated. > > Case in point: > - leaks of 64 bits kernel values to userland in compatibility > sub-mode. Sandboxing by using seccomp-bpf can restrict a process to > the 64-bit mode API. > - restricting access to the syslog() system call > That doesn't really speak to the value proposition. My concern is that we're going to spend a lot of time chasing/plugging infoleaks instead of tackling bigger problems. 8 bits of entropy is not a lot. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/