Re: Documenting the proposal for TPM 2.0 security in the face of bus interposer attacks

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>,
	linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org, monty.wiseman@ge.com,
	Monty Wiseman <montywiseman32@gmail.com>,
	Matthew Garrett <mjg59@google.com>
Subject: Re: Documenting the proposal for TPM 2.0 security in the face of bus interposer attacks
Date: Wed, 21 Nov 2018 01:52:45 +0200	[thread overview]
Message-ID: <20181120235245.GK8391@linux.intel.com> (raw)
In-Reply-To: <20181120213345.GC22023@ziepe.ca>

On Tue, Nov 20, 2018 at 02:33:45PM -0700, Jason Gunthorpe wrote:
> So it really is essential that all steps, including the BIOS use
> secure PCR updates, or you may as well not bother in Linux, at least
> for security reasons.
> 
> And I think you were on the right track, the TPM should have a
> per-boot authorization that flows through all layers of the TPM stack
> and guarantees the TPM hasn't been rebooted and with crypto prevents
> lost PCR updates. 
> 
> But that does require standardization, as we do need the BIOS to
> participate.

These talks were already started before LSS 2018 on chat session.
The idea would be to promote the same approach for BIOS.

I see what James is doing a piece, not a full solution but you
have to start from somewhere.

As an opt-in feature it should be ok.

/Jarkko