Re: [PATCH v3 0/7] tpm: TPM2.0 eventlog securityfs support

["Stefan Berger" <stefanb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>]

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Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote on 09/20/2016 
06:04:23 AM:


> 
> On Mon, Sep 19, 2016 at 10:50:15AM -0400, Stefan Berger wrote:
> >    > You also fail to explain how this should work with ACPI even 
though
> >    > we know that there does not exist any kind for event log through 
ACPI
> >    > with TPM 2.0 hardware. I.e. just by reading the commits I 
canobviously
> >    > see that you are doing major untested code path changes.
> > 
> >    That's true there there's not spec for a BIOS at the moment and I 
would
> >    expect that TCG will likely not write one. Likely all vendors have 
moved
> >    on to (U)EFI. We realized this also while implementing TPM 2 
support for
> >    SeaBIOS and I ended up reusing the ACPI TCPA table but adopted the 
EFI
> >    specified log format with that special first entry. Can we 
> accomodate that
> >    ?
> 
> Does that match to "SHA1 Event Log Entry Format" defined in [1]? In
> addition "Crypto Agile Log Entry Format" must be supported.

SeaBIOS supports the SHA1 Event Log Entry Format [5.1 in that spec]. It 
uses it for TPM 1.2.

https://code.coreboot.org/p/seabios/source/tree/master/src/std/tcg.h#L521

In case of TPM 2 it will write the first log entry in the format of the 
Event Log Header [5.3].

https://code.coreboot.org/p/seabios/source/tree/master/src/std/tcg.h#L521

All subsequent entries in the log will be written in Crypto Agile Log 
Entry Format [5.2].

Again: 
https://code.coreboot.org/p/seabios/source/tree/master/src/std/tcg.h#L521

UEFI may write into some special buffer that the OS can get to via an API 
call. In case of SeaBIOS this buffer is just in the TCPA ACPI table, as in 
TPM 1.2.


> 
> Philip: what was the UEFI handover procedure that was discussed in
> TPM BoF at LSS 2016?
> 
> >       Stefan
> 
> [1] http://www.trustedcomputinggroup.org/wp-content/uploads/EFI-
> Protocol-Specification-rev13-160330final.pdf
> 
> /Jarkko
> 



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