Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756616Ab1E0RBM (ORCPT ); Fri, 27 May 2011 13:01:12 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:42722 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752279Ab1E0RBH (ORCPT ); Fri, 27 May 2011 13:01:07 -0400 Date: Fri, 27 May 2011 19:00:45 +0200 From: Ingo Molnar To: Linus Torvalds Cc: "Rafael J. Wysocki" , Dan Rosenberg , Tony Luck , linux-kernel@vger.kernel.org, davej@redhat.com, kees.cook@canonical.com, davem@davemloft.net, eranian@google.com, adobriyan@gmail.com, penberg@kernel.org, hpa@zytor.com, Arjan van de Ven , Andrew Morton , Valdis.Kletnieks@vt.edu, pageexec@freemail.hu Subject: Re: [RFC][PATCH] Randomize kernel base address on boot Message-ID: <20110527170045.GB4356@elte.hu> References: <1306269105.21443.20.camel@dan> <201105270018.36835.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1069 Lines: 29 * Linus Torvalds wrote: > If you compile your own kernel version, you're already home free, > and load-time randomization is pointless. Most successful exploits work in two steps: first a local exploit (weak password with a user, stupid script escaping bug, or a buffer overflow somewhere), then a local kernel exploit to gain root and kernel access. (for a rootkit and what not) Straight remote root exploits are pretty rare - and per system relinking only protects against that. The problem with your relinking solution is that a local attacker can easily figure out where the kernel is. So this does not protect against the more common break-in scenario. Kernel image randomization makes this last step really indeterministic and thus dangerous to attackers. Thanks, Ingo -- 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/