linux-kernel - Re: TPM/EFI issue [Was: Linux 6.12]

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Message-ID: <ca741d8eade72aa68c389a88d2520f4fe541a1e7.camel@HansenPartnership.com>
Date: Wed, 27 Nov 2024 11:24:01 -0500
From: James Bottomley <James.Bottomley@...senPartnership.com>
To: Jiri Slaby <jirislaby@...nel.org>, Linus Torvalds
	 <torvalds@...ux-foundation.org>, Linux Kernel Mailing List
	 <linux-kernel@...r.kernel.org>
Cc: Peter Hüwe <PeterHuewe@....de>, Jarkko Sakkinen
	 <jarkko@...nel.org>, Jason Gunthorpe <jgg@...pe.ca>, 
	linux-integrity@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>, 
	"linux-efi@...r.kernel.org"
	 <linux-efi@...r.kernel.org>
Subject: Re: TPM/EFI issue [Was: Linux 6.12]

On Wed, 2024-11-27 at 07:46 +0100, Jiri Slaby wrote:
> Cc TPM + EFI guys.
> 
> On 17. 11. 24, 23:26, Linus Torvalds wrote:
> > But before the merge window opens, please give this a quick test to
> > make sure we didn't mess anything up. The shortlog below gives you
> > the
> > summary for the last week, and nothing really jumps out at me. A
> > number of last-minute reverts, and some random fairly small fixes
> > fairly spread out in the tree.
> 
> Hi,
> 
> there is a subtle bug in 6.12 wrt TPM (in TPM, EFI, or perhaps in 
> something else):
> https://bugzilla.suse.com/show_bug.cgi?id=1233752
> 
> Our testing (openQA) fails with 6.12:
> https://openqa.opensuse.org/tests/4657304#step/trup_smoke/26
> 
> The last good is with 6.11.7:
> https://openqa.opensuse.org/tests/4648526
> 
> In sum:
> TPM is supposed to provide a key for decrypting the root partitition,
> but fails for some reason.
> 
> It's extremely hard (so far) to reproduce outside of openQA (esp.
> when 
> trying custom kernels).
> 
> Most of the 6.12 TPM stuff already ended in (good) 6.11.7. I tried to
> revert:
>    423893fcbe7e tpm: Disable TPM on tpm2_create_primary() failure
> from 6.12 but that still fails.
> 
> We are debugging this further, this is just so you know.
> 
> Or maybe you have some immediate ideas?

Well, it looks like you eliminated the TPM changes:

https://bugzilla.suse.com/show_bug.cgi?id=1233752#c6

So it must be something in the logging or event recording code.  The
first thing to check is can you run a replay of the log to get the end
PCR values?  The binary for that is

tsseventextend -sim -v -if
/sys/kernel/security/tpm0/binary_bios_measurements

You'll have to check the values it gives against the values in 

/sys/class/tpm/tpm0/tpm-sha256

Probably also check sha1 to see if it matches.

Regards,

James