linux-kernel - Re: [PATCH] x86: Lock down MSR writing in secure boot

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Message-ID: <1360422712.18083.24.camel@x230.lan>
Date:	Sat, 9 Feb 2013 15:11:53 +0000
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	Kees Cook <keescook@...omium.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	linux-security-module <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH] x86: Lock down MSR writing in secure boot

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.