Re: [tpm2] facilitating BIOS update with seamless PCR policy change

[Petko Manolov <sti at nucleusys.com>]

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	Hello,

Just FYI - another fTPM is giving me the same error:

WARNING:esys:src/tss2-esys/api/Esys_Unseal.c:295:Esys_Unseal_Finish() Received TPM Error
ERROR:esys:src/tss2-esys/api/Esys_Unseal.c:101:Esys_Unseal() Esys Finish ErrorCode (0x0000008f)
ERROR: Esys_Unseal(0x8F) - tpm:handle(unk):invalid nonce size or nonce value mismatch
ERROR: Unseal failed!
ERROR: Unable to run tpm2_unseal

The machine is LENOVO P310, BIOS FWKT97A 11/08/2018, Sunrise Point-H chipset.  
Could you please give me some pointers as to how this could be worked around?


thanks,
Petko


On 19-02-18 10:20:26, Petko Manolov wrote:
> I am sorry that this didn't go through because of the attached script.  I'm 
> embedding it to this email so i'd like to apologize about the bloat.
> 
> ---
> 
> #!/bin/bash
> 
> source common.sh
> 
> #   Create a signing authority
> openssl genrsa -out signing_key_private.pem 2048
> openssl rsa -in signing_key_private.pem -out signing_key_public.pem -pubout
> tpm2_loadexternal -G rsa -a o -u signing_key_public.pem -o signing_key.ctx \
> 	-n signing_key.name
> 
> echo "Signing authority created"
> 
> #   Create a policy to be authorized like a pcr policy:
> tpm2_pcrlist -L $PCRS -o pcrs.sha256
> tpm2_startauthsession -S session.ctx
> tpm2_policypcr -S session.ctx -L $PCRS -F pcrs.sha256 -f pcr.policy
> tpm2_flushcontext -S session.ctx
> rm -f session.ctx
> 
> echo "pcr policy created"
> 
> #   Sign the policy
> openssl dgst -sha256 -sign signing_key_private.pem -out pcr.signature pcr.policy
> 
> echo "policy is signed"
> 
> #   Authorize the policy in the policy digest:
> tpm2_startauthsession -S session.ctx
> tpm2_policyauthorize -S session.ctx -o authorized.policy -f pcr.policy \
> 	-n signing_key.name
> tpm2_flushcontext -S session.ctx
> rm -f session.ctx
> 
> echo "policy authorized"
> 
> #   Create a TPM object like a sealing object with the authorized policy
> #   based authentication:
> echo "secret to seal 123" > secret_file
> tpm2_createprimary -Q -a o -g sha256 -G rsa -o prim.ctx
> tpm2_create -Q -g sha256 -u sealing_pubkey.pub -r sealing_prikey.pub \
> 	-I secret_file -C prim.ctx -L authorized.policy
> 
> echo "sealing object created"
> 
> #   Satisfy policy and unseal the secret:
> tpm2_verifysignature -c signing_key.ctx -G sha256 -m pcr.policy \
> 	-s pcr.signature -t verification.tkt -f rsassa
> tpm2_startauthsession -a -S session.ctx
> tpm2_policypcr -Q -S session.ctx -L $PCRS -f pcr.policy
> tpm2_policyauthorize -S session.ctx -o authorized.policy -f pcr.policy \
> 	-n signing_key.name -t verification.tkt
> tpm2_load -Q -C prim.ctx -u sealing_pubkey.pub -r sealing_prikey.pub \
> 	-o sealing_key.ctx
> tpm2_unseal -p "session:session.ctx" -c sealing_key.ctx -o unsealed
> cat unsealed
> tpm2_flushcontext -S session.ctx
> rm -f session.ctx unsealed
> 
> echo "the end"
> 
> ---
> 
> 
> thanks,
> Petko
> 
> 
> On 19-02-18 09:48:37, Petko Manolov wrote:
> > 	Hello again,
> > 
> > I managed to get authorized PCR policies to work for me.  The attached script 
> > works fine on my thinkpad and on rpi3 with Infineon's SLB9670 SPI TPM2.
> > 
> > However, i stumbled upon a problem with an fTPM implementation in a very recent 
> > AMI BIOS.  Everything seems to be working properly, until i get tpm2_unseal to 
> > give me the error below.  The tpm2-tools is built with at-the-time tip of git 
> > commit id:
> > 
> > 	872076e1b31f22b18391c6761d47575a93891cd7
> > 
> > tpm2_unseal -v:
> > 
> > 	tool="tpm2_unseal" version="3.0.2-858-g88956e75" tctis="dynamic" tcti-default=tabrmd dlclose=enabled
> > 
> > tpm-tss is v2.1.0 and tpm-abrmd is v2.0.3.  Unfortunately the error message does 
> > not mean much for me so any help will be greatly appreciated.
> > 
> > 
> > thanks,
> > Petko
> > 
> > 
> > 
> > ---
> > 
> > Generating RSA private key, 2048 bit long modulus
> > ..............................+++++
> > ...........................................+++++
> > e is 65537 (0x10001)
> > writing RSA key
> > transient-context: signing_key.ctx
> > name: 0x000b5e069ba4b591842c25155d812f635970dabe7cee663aff121088940f88e2da80
> > Signing authority created
> > sha256:
> >   0 : 0x647992CBC9EEBF49D367559D870620C324B1A4307EB2A6166F1ACEC0DC186AEA
> >   1 : 0x519B03509291B643DA7FEC4407FFC47C1C18AF706A611ECA1C159D4608342338
> >   2 : 0x369BB94CEB4A1DF8E76720141B64C57EC70E6C620F07B27E335E70AD2DDC25DB
> >   3 : 0x369BB94CEB4A1DF8E76720141B64C57EC70E6C620F07B27E335E70AD2DDC25DB
> > session-context: session.ctx
> > policy-digest: 0x22035897291FE4681D7800685BFC5C73EBCBB88C7A579AB20C2E345A9815FDFE
> > pcr policy created
> > policy is signed
> > session-context: session.ctx
> > 45a41a53c9f74f09b72151af6ffdd199fe1129eff2b749b8e481b6b21f2281f1
> > policy authorized
> > sealing object created
> > session-context: session.ctx
> > 45a41a53c9f74f09b72151af6ffdd199fe1129eff2b749b8e481b6b21f2281f1
> > WARNING:esys:../tpm2-tss/src/tss2-esys/api/Esys_Unseal.c:295:Esys_Unseal_Finish() Received TPM Error
> > ERROR:esys:../tpm2-tss/src/tss2-esys/api/Esys_Unseal.c:101:Esys_Unseal() Esys Finish ErrorCode (0x0000008f)
> > ERROR: Esys_Unseal(0x8F) - tpm:handle(unk):invalid nonce size or nonce value mismatch
> > ERROR: Unseal failed!
> > ERROR: Unable to run tpm2_unseal
> > cat: unsealed: No such file or directory
> > the end
> 
> 
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