Messages in this thread | | | Date | Wed, 30 Sep 2009 08:54:48 +0200 | From | Pavel Machek <> | Subject | Re: [GIT PULL] x86/txt for v2.6.32 |
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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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