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

From: Matthew Garrett
Date: Fri Feb 08 2013 - 18:27:10 EST

On Sat, 2013-02-09 at 00:06 +0100, Borislav Petkov wrote:
> On Fri, Feb 08, 2013 at 02:30:52PM -0800, H. Peter Anvin wrote:
> > Also, keep in mind that there is a very simple way to deny MSR access
> > completely, which is to not include the driver in your kernel (and not
> > allow module loading, but if you can load modules you can just load a
> > module to muck with whatever MSR you want.)
> I was contemplating that too. What is the use case of having
> msr.ko in a secure boot environment? Isn't that an all-no-tools,
> you-can't-do-sh*t-except-what-you're-explicitly-allowed-to environment which
> simply doesn't need to write MSRs in the first place?

Well, sure, distributions could build every kernel twice. That seems a
little excessive, though.
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