Re: [PATCH v7 2/2] tpm: add securityfs support for TPM 2.0 firmware event log

[Jarkko Sakkinen]

On Tue, Jan 03, 2017 at 01:09:18PM +0530, Nayna wrote:
> 
> 
> On 01/03/2017 03:42 AM, Jarkko Sakkinen wrote:
> > On Sun, Dec 11, 2016 at 12:35:33AM -0500, Nayna Jain wrote:
> > > Unlike the device driver support for TPM 1.2, the TPM 2.0 does
> > > not support the securityfs pseudo files for displaying the
> > > firmware event log.
> > > 
> > > This patch enables support for providing the TPM 2.0 event log in
> > > binary form. TPM 2.0 event log supports a crypto agile format that
> > > records multiple digests, which is different from TPM 1.2. This
> > > patch enables the tpm_bios_log_setup for TPM 2.0  and adds the
> > > event log parser which understand the TPM 2.0 crypto agile format.
> > > 
> > > Signed-off-by: Nayna Jain <nayna@xxxxxxxxxxxxxxxxxx>
> > 
> > There is something fundamentally wrong in this commit.
> > 
> > You must not allow this feature unless CONFIG_OF is set. It is the only
> > interface where the supply path of the event log is well defined on
> > platforms that include a TPM 2.0 chip.
> 
> As per current implementation, if ACPI with TPM 2.0 doesn't support event
> log, tpm_read_log_acpi() is expected to return rc and tpm_bios_log_setup
> will not create securityfs. This is inline with our design for TPM 1.2 event
> log.

At minimum you must have a check for TPM_CHIP_FLAG_TPM2 in the beginning
of tpm_read_log_acpi. It is wrong to even try to open TCPA in this case.

/Jarkko