Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753227AbZF1WrL (ORCPT ); Sun, 28 Jun 2009 18:47:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752535AbZF1Wq5 (ORCPT ); Sun, 28 Jun 2009 18:46:57 -0400 Received: from tundra.namei.org ([65.99.196.166]:33355 "EHLO tundra.namei.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752445AbZF1Wq5 (ORCPT ); Sun, 28 Jun 2009 18:46:57 -0400 Date: Mon, 29 Jun 2009 08:46:07 +1000 (EST) From: James Morris To: Pavel Machek cc: Chris Wright , Joseph Cihula , Ingo Molnar , linux-kernel@vger.kernel.org, arjan@linux.intel.com, hpa@zytor.com, andi@firstfloor.org, jbeulich@novell.com, peterm@redhat.com, gang.wei@intel.com, shane.wang@intel.com Subject: Re: [RFC v4][PATCH 2/2] intel_txt: Intel(R) TXT and tboot kernel support In-Reply-To: <20090626213045.GA22359@elf.ucw.cz> Message-ID: References: <4A299051.40405@intel.com> <20090619150514.GE1389@ucw.cz> <20090619183414.GG19771@sequoia.sous-sol.org> <20090626213045.GA22359@elf.ucw.cz> User-Agent: Alpine 2.00 (LRH 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1467 Lines: 37 On Fri, 26 Jun 2009, Pavel Machek wrote: > > > Also, hardware security measures such as TXT are important in providing > > stronger mechanisms to ensure that kernel security mechanisms are > > functioning correctly. > > I don't get it. How does TXT help kernel security mechanisms? Kernel security mechanisms can be subverted and bypassed in the case of an exploitable kernel vulnerability, or from exploitable buggy hardware (e.g. which can access the entire host's memory via DMA). Attacks on kernel security mechanisms have been describe in detail, see: http://www.phrack.com/issues.html?issue=66&id=15#article This is close to impossible to solve from within the kernel alone. Hardware support is required to allow protection of the IO space (e.g. via IOMMU/VT-d), and to allow verification of the kernel itself (via TXT). A significant advance in this area is LKIM: "Linux kernel integrity measurement using contextual inspection" http://portal.acm.org/citation.cfm?id=1314354.1314362 (Unfortunately, the ACM has not made this freely available, although I understand that individual authors are allowed to distribute their own papers as they see fit). - James -- James Morris -- 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/