linux-kernel - Re: [PATCH 1/5 v2] PM / hibernate: Create snapshot keys handler

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Message-ID: <20190111154146.GA12093@linux.intel.com>
Date:   Fri, 11 Jan 2019 17:53:18 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     joeyli <jlee@...e.com>
Cc:     James Bottomley <James.Bottomley@...senPartnership.com>,
        Andy Lutomirski <luto@...nel.org>,
        Stephan Mueller <smueller@...onox.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "Lee, Chun-Yi" <joeyli.kernel@...il.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>,
        LKML <linux-kernel@...r.kernel.org>, linux-pm@...r.kernel.org,
        keyrings@...r.kernel.org,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Chen Yu <yu.c.chen@...el.com>,
        Oliver Neukum <oneukum@...e.com>,
        Ryan Chen <yu.chen.surf@...il.com>,
        David Howells <dhowells@...hat.com>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        Randy Dunlap <rdunlap@...radead.org>,
        Jann Horn <jannh@...gle.com>
Subject: Re: [PATCH 1/5 v2] PM / hibernate: Create snapshot keys handler

On Thu, Jan 10, 2019 at 02:11:55AM +0800, joeyli wrote:
> > Well, I think here, if we were actually trying to solve the problem of
> > proving the hibernated image were the same one we would need to prove
> > some log of the kernel operation came to a particular value *after* the
> > hibernated image were restored ... it's not really possible to
> > condition key release which must occur before the restore on that
> > outcome, so it strikes me we need more than a simple release bound to
> > PCR values.
> >
> 
> hm... I am studying your information. But I have a question...
> 
> If PCR is not capped and the root be compromised, is it possible that a
> sealed bundle also be compromised? 
> 
> Is it possible that kernel can produce a sealed key with PCR by TPM when
> booting? Then kernel caps a PCR by a constant value before the root is
> available for userland. Then the sealed key can be exposed to userland
> or be attached on hibernate image. Even the root be compromised, the TPM
> trusted key is still secure.

I think this even might be reasonable. Especially when we land James'
encrypted sessions patches at some point.

/Jarkko