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

From: H. Peter Anvin
Date: Tue Feb 12 2013 - 19:49:44 EST

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?


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