From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot Date: Tue, 12 Feb 2013 16:48:12 -0800 Message-ID: <511AE2CC.5040705@zytor.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1360422712.18083.24.camel@x230.lan> Sender: linux-security-module-owner@vger.kernel.org To: Matthew Garrett Cc: Borislav Petkov , Kees Cook , LKML , Thomas Gleixner , Ingo Molnar , "x86@kernel.org" , "linux-efi@vger.kernel.org" , linux-security-module List-Id: linux-efi@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