On Tue, 2020-01-14 at 00:18 +0000, Paul Moore (pmoore2) wrote:
> On Mon, 2020-01-13 at 20:33 +0000, Paul Moore (pmoore2) via tboot-devel wrote:
> > On Thu, 2020-01-09 at 14:59 +0000, Hawrylko, Lukasz wrote:
> > > On Fri, 2020-01-03 at 20:26 +0000, Paul Moore (pmoore2) via tboot-devel
> > > wrote:
> > > > 
> > > > Lukasz, is there a way to generate PCR hashes for all supported
> > > > algorithms like tboot does for PCR17/18?
> > > > 
> > > > -Paul
> > > > 
> > >  
> > > Hello Paul
> > > 
> > > I looks like you can't create policy with different hash algorithms,
> > > look at tb_policy_t structure in tb_policy.h There is one field for
> > > setting hash algorithm that is common to all policy entries.
> > 
> > Have you been able to create a VLP which causes tboot to extend the
> > TPM's sha256 PCR bank?
> > 
> 
> After digging through the code some more, it looks like the key to
> making this work is to specify the correct "extpol=" parameter on the
> tboot command line. It appears to be TPM and ACM dependent (?) so I'm
> not sure this will work for everyone, but on my system
> "extpol=embedded" caused tboot to extend all of the TPM PCR banks;
> "extpol=agile" on my system caused the ACM to reset the system.
> 
> -Paul
> 

As far as I remember I was able to extend SHA256 PCRs, because this is
the only way to test my changes in tb_polgen. I am not sure, but I think
that you have to pass "extpol=sha256" in command line and than you can
work with SHA256 policies. Did you try to do that? I will try tomorrow
how agile and embedded options work on my platform.

Thanks,
Lukasz





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