Re: [tpm2] [tpm2-software/tpm2-tools] NV write/read with authorized policy (#1281)

Re: [tpm2] [tpm2-software/tpm2-tools] NV write/read with authorized policy (#1281)

[Roberts, William C]

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> -----Original Message-----
> From: Kai Che [mailto:notifications(a)github.com]
> Sent: Wednesday, January 16, 2019 8:00 AM
> To: tpm2-software/tpm2-tools <tpm2-tools(a)noreply.github.com>
> Cc: Subscribed <subscribed(a)noreply.github.com>
> Subject: [tpm2-software/tpm2-tools] NV write/read with authorized policy
> (#1281)
> 
> Hello everyone,
> 
> I'm trying to write/read a NV area which was defined with a policy output from
> tpm2_policyauthorize:

I'm assuming you're setup steps would be here and you're just showing the attempt
To define a new space with the policy.

> tpm2_policyauthorize -S session.ctx -o authorized.policy -f pcr.policy -n signing_key.name
> tpm2_nvdefine -x 0x1500001 -a 0x40000001 -s 32 -t "policyread|policywrite" -L authorized.policy
> tpm2_nvread -x 0x1500001 -s 32 -L sha256:8 -o 0 

On master, I am seeing no way to pass the authorizing session context to tpm2_nvread. The options to
NV read for PCR policy satisfaction are all internal, and quite limited in support.

You really would want something like:
tpm2_nvread -p session=session.ctx <args|opts>

This way the first handle of the sessions array can be specified.

You also need tpm2-abrmd and not /dev/tpm0 or /dev/tpmrm0 as extended sessions (ie
Session blobs between tool invocations) is an abrmd only feature.

Sorry this support is not there currently, but it's on the roadmap for 2019. My major goal for the 2019
Release is to have:
1. proper session/password support. Each part of the session array should be specifiable. 
2. HMAC passwords
3. Consistent options (command line interface will freeze at 4.0)

> ERROR: Failed to read NVRAM area at index 0x1500001
> ERROR: Tss2_Sys_NV_Read(0x99D) - tpm:session(1):a policy check failed
> ERROR: Unable to run tpm2_nvread
> 
> Write/read with a "normal" PCR policy is working fine with the proper PCR values:
> tpm2_nvdefine -x 0x1500001 -a 0x40000001 -s 32 -t "policyread|policywrite" -L
> pcr.policy
> 
> How can I access the NV area with an authorized policy?
> 
> Thanks and best regards,
> 
> Kai
> 
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