Re: [tpmdd-devel] [PATCH 09/13] tpm: Pull everything related to sysfs into tpm-sysfs.c

[Peter Hüwe]

Am Freitag, 4. Oktober 2013, 21:17:36 schrieb Stefan Berger:
> On 10/04/2013 01:08 PM, Jason Gunthorpe wrote:
> > On Mon, Sep 30, 2013 at 05:09:51PM -0500, Joel Schopp wrote:
> >>> So far, nobody I have talked to has offered any strong opinions on
> >>> what locality should be used or how it should be set. I think finding
> >>> a developer of trousers may be the most useful to talk about how the
> >>> ioctl portion of this would need to be set up - if someone is actually
> >>> needed.
> >> 
> >> I am a TrouSerS developer and am ccing Richard, another TrouSerS
> >> developer, and ccing the trousers-tech list.  It would be good if you
> >> could elaborate on the question and context for those not following the
> >> entire thread, myself included.
> > 
> > Two questions:
> > 
> > Is userspace interested in using the TPM Locality feature, and if so
> > is there any thoughts on what the interface should be?
> 
> In terms of interface it should probably be an ioctl so that whoever
> holds the fd to /dev/tpm0 gets to choose the locality.
> 
> Locality allows the resetting of certain PCRs. See section 3.7 in
> 
> http://www.trustedcomputinggroup.org/files/static_page_files/8E45D739-1A4B-> B294-D06274E7047730FD/TCG_PCClientTPMInterfaceSpecification_TIS__1-3_27_032
> 12013.pdf
> 
> Locality 4 can only be used by the hardware (section 2.2).


Afaik Locality 3 (and sometimes 2) is often also "locked down"/filtered after 
the bios phase.


>From 
http://www.intel.com/content/dam/www/public/us/en/documents/guides/intel-txt-software-development-guide.pdf

"The storage spaces accessible within a TPM device are grouped by a locality 
attribute and are a separate set of address ranges from the Intel TXT Public 
and Private spaces.
The following localities are defined:
Locality 0 : Non trusted and legacy TPM operation
Locality 1 : An environment for use by the Trusted Operating System
Locality 2 : Trusted OS
Locality 3 : Authenticated Code Module
Locality 4 : Intel TXT hardware use only"

(I know that's "only" Intel's view and not a TCG spec)

Thanks,
Peter
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