Re: [PATCH v5 0/1] add sysfs exports for TPM 2 PCR registers

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On Wed, 2021-01-13 at 22:48 +0200, Jarkko Sakkinen wrote:
> On Tue, Jan 12, 2021 at 05:59:57PM -0800, James Bottomley wrote:
> > This represents v5 which has the spelling mistake fixed and the
> > WARN
> > on unrecognized TPM hash algorithm becoming a dev_err.
> > 
> > We've had a fairly extensive discussion and iterated to agreement
> > on
> > the output format, which becomes our ABI being one single compact
> > hex
> > representation of the hash value per file according to sysfs rules,
> > with the file hierarchy going under
> > 
> >   /sys/class/tpm/tmp<x>/pcr-<hash>/<pcr number>
> > 
> > So to get the value of PCR 7 in the sha256 bank of the default TPM
> > I'd do
> > 
> >    cat /sys/class/tpm/tpm0/pcr-sha256/7
> >    2ED93F199692DC6788EFA6A1FE74514AB9760B2A6CEEAEF6C808C13E4ABB0D42
> > 
> > If you need the binary hash of a set of PCRs, as is required for
> > TPM
> > policy statements that lock to PCRs, you'd use something like:
> > 
> >   cat /sys/class/tpm/tpm0/pcr-sha256/{1,6,7}|xxd -r -p|sha256sum
> > 
> > Which produces the binary hash of PCRs 1, 6 and 7 in that order.
> > 
> > Note that this patch also adds the sha1 bank for TPM 1.2 in the
> > same
> > manner (one file per PCR) but does not remove the existing pcrs
> > file
> > which has the space separated all PCRs in one file format of
> > 
> >   PCR-00: 7D 29 CB 08 0C 0F C4 16 7A 0E 9A F7 C6 D3 97 CD C1 21 A7
> > 69 
> >   PCR-01: 9C B6 79 4C E4 4B 62 97 4C AB 55 13 1A 2F 7E AE 09 B3 30
> > BE 
> >   ...
> > 
> > 
> > James
> > 
> > ---
> > 
> > James Bottomley (1):
> >   tpm: add sysfs exports for all banks of PCR registers
> > 
> >  drivers/char/tpm/tpm-sysfs.c | 179
> > +++++++++++++++++++++++++++++++++++
> >  include/linux/tpm.h          |   9 +-
> >  2 files changed, 187 insertions(+), 1 deletion(-)
> > 
> > -- 
> > 2.26.2
> > 
> 
> After clearing out Greg's remarks, can you use jarkko@xxxxxxxxxx
> for the next version?

Sorry, it's a force of habit process: i go back to version n-1 and copy
the to and cc list ... so the promise to sent to kernel.org didn't get
realised.

I'll just do a resend since there are no changes requested.

James





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