From: Jason Gunthorpe <jgg@ziepe.ca>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
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: Mon, 19 Nov 2018 14:44:26 -0700 [thread overview]
Message-ID: <20181119214426.GK4890@ziepe.ca> (raw)
In-Reply-To: <1542663281.2910.44.camel@HansenPartnership.com>
On Mon, Nov 19, 2018 at 01:34:41PM -0800, James Bottomley wrote:
> On Mon, 2018-11-19 at 14:19 -0700, Jason Gunthorpe wrote:
> [...]
> > Sure, for stuff working with shared secrets, etc, this make sense.
> > But PCR extends are not secret, so there is no reason to encrypt them
> > on the bus.
>
> OK, there's a miscommunication here. I believe the current document
> states twice that there's no encryption for PCR operations. We merely
> use a salted HMAC session to ensure that they're reliably received by
> the TPM and not altered in-flight.
Sure, but again, what is this preventing?
If you accept that PCB trust is essential for PCR security, then I
think trusting the PCB to deliver the PCR extends is perfectly fine.
> > > In theory, but we don't seem to have one. The theory is that TPMs
> > > come provisioned according to the TCG guidance which specifies RSA
> > > and EC storage keys be at 81000001 and 81000002 respectively ... it
> > > just seems that the current TPM generation don't respect this, so
> > > they come with no permanent keys at all.
> >
> > Seems surprising.. And the use models you have don't alwaus load a
> > key that could be used for this?
>
> I think it's because Microsoft realised after the first generation of
> TPM 2.0s that not having any key at all was a problem, so lots of them
> shipped before the spec got updated and manufacturers are somewhat slow
> to retool production lines. My TPM 2.0 doesn't even have an EC
> certificate (although Nuvoton now claims this was a manufacturing
> mistake) never mind a derived primary key.
Ah, the usual mess in TPM land then :)
Jason
next prev parent reply other threads:[~2018-11-19 21:44 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 17:34 Documenting the proposal for TPM 2.0 security in the face of bus interposer attacks James Bottomley
2018-11-19 20:05 ` Jason Gunthorpe
2018-11-19 20:20 ` James Bottomley
2018-11-19 21:19 ` Jason Gunthorpe
2018-11-19 21:34 ` James Bottomley
2018-11-19 21:44 ` Jason Gunthorpe [this message]
2018-11-19 22:36 ` James Bottomley
2018-11-19 23:08 ` Jason Gunthorpe
2018-11-20 0:54 ` James Bottomley
2018-11-20 3:05 ` Jason Gunthorpe
2018-11-20 17:17 ` James Bottomley
2018-11-20 21:33 ` Jason Gunthorpe
2018-11-20 22:34 ` James Bottomley
2018-11-20 23:39 ` Jason Gunthorpe
2018-11-21 2:24 ` EXTERNAL: " Jeremy Boone
2018-11-21 5:16 ` Jason Gunthorpe
2018-11-20 23:52 ` Jarkko Sakkinen
2018-11-20 23:41 ` Jarkko Sakkinen
2018-11-20 11:10 ` Jarkko Sakkinen
2018-11-20 12:41 ` Jarkko Sakkinen
2018-11-20 17:25 ` James Bottomley
2018-11-20 23:13 ` Jarkko Sakkinen
2018-11-20 23:58 ` James Bottomley
2018-11-21 0:33 ` EXTERNAL: " Jeremy Boone
2018-11-21 6:37 ` Jarkko Sakkinen
2018-11-21 5:42 ` Jason Gunthorpe
2018-11-21 7:18 ` Jarkko Sakkinen
[not found] ` <F10185EF-C618-45DC-B1F3-0053B8FE417F@gmail.com>
2018-11-21 9:07 ` Jarkko Sakkinen
2018-11-21 9:14 ` Jarkko Sakkinen
2018-11-20 17:23 ` James Bottomley
2018-11-20 23:12 ` Jarkko Sakkinen
2018-12-10 16:33 ` Ken Goldman
2018-12-10 17:30 ` James Bottomley
2018-12-11 21:47 ` Ken Goldman
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