From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: "Ard Biesheuvel" <ardb@kernel.org>, "Loïc Yhuel" <loic.yhuel@gmail.com>
Cc: linux-integrity@vger.kernel.org, matthewgarrett@google.com,
javierm@redhat.com
Subject: Re: [PATCH] tpm: check event log version before reading final events
Date: Thu, 14 May 2020 04:09:13 +0300 [thread overview]
Message-ID: <ab9df4468cc294c67a67ef336019379033e7c90c.camel@linux.intel.com> (raw)
In-Reply-To: <CAMj1kXFfLvUXU1A-7jnh3KMy5Qguhq0k9Cw=O0iBmbToowV_8A@mail.gmail.com>
On Tue, 2020-05-12 at 08:44 +0200, Ard Biesheuvel wrote:
> Hi Loïc,
>
> Thanks for the fix.
>
> On Tue, 12 May 2020 at 06:01, Loïc Yhuel <loic.yhuel@gmail.com> wrote:
> > This fixes the boot issues since 5.3 on several Dell models when the TPM
> > is enabled. Depending on the exact grub binary, booting the kernel would
> > freeze early, or just report an error parsing the final events log.
> >
> > We get an event log in the SHA-1 format, which doesn't have a
> > tcg_efi_specid_event_head in the first event, and there is a final events
> > table which doesn't match the crypto agile format.
> > __calc_tpm2_event_size reads bad "count" and "efispecid->num_algs", and
> > either fails, or loops long enough for the machine to be appear frozen.
> >
> > So we now only parse the final events table, which is per the spec always
> > supposed to be in the crypto agile format, when we got a event log in this
> > format.
> >
>
> So what functionality do we lose here? Can we still make meaningful
> use of the event log without the final log? I thought one was
> incomplete without the other?
Nope it would be incomplete [*].
So probably would make sense to at least issue a warning in this case.
[*] https://www.kernel.org/doc/Documentation/security/tpm/tpm_event_log.rst
/Jarkko
next prev parent reply other threads:[~2020-05-14 1:09 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-12 4:01 [PATCH] tpm: check event log version before reading final events Loïc Yhuel
2020-05-12 6:44 ` Ard Biesheuvel
2020-05-12 11:40 ` Loïc Yhuel
2020-05-12 12:30 ` Ard Biesheuvel
2020-05-14 10:51 ` Jarkko Sakkinen
2020-05-14 1:09 ` Jarkko Sakkinen [this message]
2020-05-14 8:10 ` Ard Biesheuvel
2020-05-14 23:44 ` Jarkko Sakkinen
2020-05-12 17:45 ` Javier Martinez Canillas
2020-05-12 18:45 ` Jerry Snitselaar
2020-05-12 20:08 ` Matthew Garrett
2020-05-14 10:53 ` Jarkko Sakkinen
2020-05-14 11:28 ` Loïc Yhuel
2020-05-14 11:31 ` Ard Biesheuvel
2020-05-15 0:03 ` Jarkko Sakkinen
2020-05-14 11:33 ` Javier Martinez Canillas
2020-05-14 12:28 ` Ard Biesheuvel
2020-05-14 12:56 ` Javier Martinez Canillas
2020-05-14 13:04 ` Ard Biesheuvel
2020-05-14 13:51 ` Javier Martinez Canillas
2020-05-14 18:06 ` Matthew Garrett
2020-05-15 15:55 ` Loïc Yhuel
2020-05-22 18:30 ` [tip: efi/urgent] " tip-bot2 for Loïc Yhuel
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