linux-kernel - Re: [GIT PULL] x86/txt for v2.6.32

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Message-ID: <20090930065448.GB11652@elf.ucw.cz>
Date:	Wed, 30 Sep 2009 08:54:48 +0200
From:	Pavel Machek <pavel@....cz>
To:	"Wang, Shane" <shane.wang@...el.com>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Cihula, Joseph" <joseph.cihula@...el.com>
Subject: Re: [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@....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

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