Re: [PATCH 1/4] integrity: TPM internel kernel interface

[Kenneth Goldman]

Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote on 08/12/2008 03:30:31 PM:

> On Mon, Aug 11, 2008 at 05:13:51PM -0400, Mimi Zohar wrote:
> >
> > I assume the concern here is that between looking up the chip and
actually
> >
> > using the chip, the TPM chip is disabled/deactivated.  Based on
> > discussions
> > with Kenneth Goldman, the TCG main specification part2: structures,
> > require
> > that even if the TPM is disabled/deactivated, the command to extend the

> > PCR
> > will succeed, but the command to read the PCR will fail with an
> > appropriate
> > error code.
>
> And what happens when the chip simply goes away due to a hotplug action?
> Or not even the actual chip goes away but just the chip driver and you
> now dereference freed memory?

Being a TCG/TPM person, I can only address the first question.  The
intent is that the TPM is soldered to the planar/motherboard (the TCG
uses the phrase "bound to the platform").  I can't imagine
any manufacturer designing a pluggable TPM.  It would subvert PCR
measurements and thus attestation, data sealing, etc.

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