From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759539Ab3BMAtk (ORCPT ); Tue, 12 Feb 2013 19:49:40 -0500 Received: from terminus.zytor.com ([198.137.202.10]:59003 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753270Ab3BMAti (ORCPT ); Tue, 12 Feb 2013 19:49:38 -0500 Message-ID: <511AE2CC.5040705@zytor.com> Date: Tue, 12 Feb 2013 16:48:12 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Matthew Garrett CC: Borislav Petkov , Kees Cook , LKML , Thomas Gleixner , Ingo Molnar , "x86@kernel.org" , "linux-efi@vger.kernel.org" , linux-security-module Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot References: <1360355671.18083.18.camel@x230.lan> <51157C9C.6030501@zytor.com> <20130208230655.GB28990@pd.tnic> <1360366012.18083.21.camel@x230.lan> <5115A4CC.3080102@zytor.com> <1360373383.18083.23.camel@x230.lan> <20130209092925.GA17728@pd.tnic> <1360422712.18083.24.camel@x230.lan> In-Reply-To: <1360422712.18083.24.camel@x230.lan> X-Enigmail-Version: 1.5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/09/2013 07:11 AM, Matthew Garrett wrote: > On Sat, 2013-02-09 at 10:29 +0100, Borislav Petkov wrote: >> On Fri, Feb 08, 2013 at 10:45:35PM -0800, Kees Cook wrote: >>> Also, _reading_ MSRs from userspace arguably has utility that doesn't >>> compromise ring-0. >> >> And to come back to the original question: what is that utility, who >> would need it on a secure boot system and why? > > Things like Turbostat are useful, although perhaps that information > should be exposed in a better way. > OK... what none of this gets into: Why should CAP_RAWIO be allowed on a secure boot system, when there are 2^n known ways of compromise a system with CAP_RAWIO? -hpa