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Date: Thu, 9 Oct 2008 11:14:51 -0700
From: Chris Wright <chrisw@sous-sol.org>
To: Pavel Machek <pavel@suse.cz>
Cc: Chris Wright <chrisw@sous-sol.org>,
       "Cihula, Joseph" <joseph.cihula@intel.com>,
       linux-kernel@vger.kernel.org, "Wang, Shane" <shane.wang@intel.com>,
       "Wei, Gang" <gang.wei@intel.com>,
       "Van De Ven, Arjan" <arjan.van.de.ven@intel.com>,
       "Mallick, Asit K" <asit.k.mallick@intel.com>,
       "Nakajima, Jun" <jun.nakajima@intel.com>,
       Chris Wright <chrisw@redhat.com>, Jan Beulich <jbeulich@novell.com>,
       mingo@elte.hu, tytso@mit.edu
Subject: Re: [RFC][PATCH 0a/3] TXT: Intel(R) Trusted Execution Technology
	support for Linux - Overview
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References: <D936D925018D154694D8A362EEB0892005AC105B@orsmsx416.amr.corp.intel.com> <20081009125311.GD1623@ucw.cz> <20081009174427.GB6912@sequoia.sous-sol.org> <20081009175938.GA12507@elf.ucw.cz>
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* Pavel Machek (pavel@suse.cz) wrote:
> I have never used trusted boot and I'm not sure I want to. Why would I
> want to do that?

So that you can reason that you've booted kernel/initrd that you wanted
to (and have established a root of trust for follow-on, like Joe's IMA
example), and in the case that you didn't (say bluepill), you have a
policy in place to handle it.

> You exit/reenter the trusted mode accross sleep... so any guarantees
> "trusted" mode does are void, right?

You exit from kernel to tboot on any shutdown, which handles the proper
teardown of the measured env (meaning you also come back on via tboot).
So things like saving tpm state, scrubbing secrets from memory, etc.

thanks,
-chris