[LTP] Hidden TPM questions in the LTP IMA posts

[Jarkko Sakkinen]

On Mon, Feb 05, 2018 at 02:34:49PM +0100, Javier Martinez Canillas wrote:
> Support for reading from EFI is what landed for this release, but only the
> TPM 1.2 (SHA1) format is supported, there's still not support for TPM 2.0
> (crypto agile). You can see that in drivers/firmware/efi/libstub/tpm.c:
> 
> void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> {
> ...
> 	status = efi_call_proto(efi_tcg2_protocol, get_event_log, tcg2_protocol,
> 				EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
> 				&log_location, &log_last_entry, &truncated);
> ...
> }
> 
> void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
> {
> 	/* Only try to retrieve the logs in 1.2 format. */
> 	efi_retrieve_tpm2_eventlog_1_2(sys_table_arg);
> }
> 
> But all the bits for TPM 2.0 (crypto agile) support seems to already be in
> drivers/char/tpm/tpm2_eventlog.c, are only missing in the EFI stub AFAICT.

This is correct. DT based platforms already support crypto agile.

> Now, on latest TCG ACPI Specification (Revision 8, August 18, 2017) [1],
> the spec does mention that the ACPI table with signature 'TPM2' can have
> the LASA and LAML as optional fields. This is mentioned in section 7.3
> "ACPI Table for TPM 2.0".

Oh, this is new to me. We can support it as soon as there is a plaform
that has it. I do not have any at this point.

/Jarkko