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Date:   Sun, 21 Feb 2021 14:44:29 -0500
From:   Ben Boeckel <me@benboeckel.net>
To:     Jarkko Sakkinen <jarkko@kernel.org>
Cc:     Matthew Garrett <matthewgarrett@google.com>,
        linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
        linux-pm@vger.kernel.org, keyrings@vger.kernel.org,
        zohar@linux.ibm.com, jejb@linux.ibm.com, corbet@lwn.net,
        rjw@rjwysocki.net, Matthew Garrett <mjg59@google.com>
Subject: Re: [PATCH 5/9] security: keys: trusted: Allow storage of PCR values
 in creation data
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 <20210220013255.1083202-6-matthewgarrett@google.com>
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On Sat, Feb 20, 2021 at 05:09:07 +0200, Jarkko Sakkinen wrote:
> Something popped into mind: could we make PCR 23 reservation dynamic
> instead of a config option.
> 
> E.g. if the user space uses it, then it's dirty and hibernate will
> fail. I really dislike the static compilation time firewall on it.

I don't know the threat model here, but couldn't hibernation then be
blocked by userspace using PCR 23 in some way (thus becoming a Denial of
Service)? Are elevated permissions required to use PCR values?

--Ben