Re: [PATCH v2 2/3] efi: call get_event_log before ExitBootServices

[Matthew Garrett]

On Thu, Sep 14, 2017 at 11:43 AM, Jarkko Sakkinen
<jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
> On Mon, Sep 11, 2017 at 12:00:21PM +0200, Thiebaud Weksteen wrote:
>> With TPM 2.0 specification, the event logs may only be accessible by
>> calling an EFI Boot Service. Modify the EFI stub to copy the log area to
>> a new Linux-specific EFI configuration table so it remains accessible
>> once booted.
>>
>> When calling this service, it is possible to specify the expected format
>> of the logs: TPM 1.2 (SHA1) or TPM 2.0 ("Crypto Agile"). For now, only the
>> first format is retrieved.
>>
>> Signed-off-by: Thiebaud Weksteen <tweek@xxxxxxxxxx>
>
> With a quick skim the code change looks good but I remember from
> Matthew's talk that there was this issue that ExitBootServices() would
> cause a yet another event?
>
> I guess you could manually synthetize that event by reading the PCR
> values right after ExitBootServices()?

I think that would involve breaking SHA1â the information should be
available in the TCG_TREE_FINAL_EVENTS configuration table, so it
/should/ just be a matter of merging the events from that into the
event log.