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SubjectRe: [GIT PULL] x86/txt for v2.6.32
On Wed 2009-09-30 10:16:55, Wang, Shane wrote:
> Arjan van de Ven wrote:
> > On Tue, 29 Sep 2009 19:13:18 +0200
> > Pavel Machek <pavel@ucw.cz> wrote:
> >
> >> Ok, and what prevents me from commenting out the MAC checking code?
> >>
> >
> > because the bios verified some code that verified the kernel which
> > includes the MAC checking code .. as part of returning from S3 ?
>
> Yes, S3 sleep/resume cause another cycle to build the measured environment.
> i.e. SINIT will verify tboot, tboot will verify kernel mem, kernel will verify userspace mem.
> If you comment out the MAC checking code in any party, the chain will lost and S3 resume will fail.
>

Ok, that means that you are protecting integrity but not secrecy?
Should that be written down in documentation, along with threat model?

So I modify the RAM content so that BIOS does not think measured
environment existed before suspend?
Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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