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From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Ken Goldman <kgold@linux.ibm.com>, linux-integrity@vger.kernel.org
Cc: linux-security-module@vger.kernel.org,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [PATCH v4 0/7] add integrity and security to TPM2 transactions
Date: Mon, 22 Oct 2018 16:55:08 +0100	[thread overview]
Message-ID: <1540223708.3012.19.camel@HansenPartnership.com> (raw)
In-Reply-To: <e773aafe-4b12-775c-9df9-0e747880a35f@linux.ibm.com>

On Mon, 2018-10-22 at 11:50 -0400, Ken Goldman wrote:
> On 10/22/2018 10:18 AM, James Bottomley wrote:
> > > 1 - Any policy that requires a password (policypassword) can
> > > substitute
> > > an HMAC (policyauthvalue) at the callers discretion.  They result
> > > in the same policy digest.
> > 
> > Right but this requires the co-operation of the policy handle
> > creator, so it's an API change.
> > 
> 
> In case it wasn't clear:  The choice is not made at the time the
> policy is calculated, nor is it made at startauthsession (when
> the policy is created).
> 
> The choice is made when the policy is being satisfied.
> 
> policypassword tells the TPM to expect a plaintext password, while
> policyauthvalue tells the TPM to expect an HMAC.
> 
> It's subtle that either policy command results in the same policy
> digest.

I understand, but the API just has a policy handle from a fully
constructed policy passed in.  There's no way to deconstruct this even
to know if it has auth requirements and what type.  To get that info we
 have to see the policy commands that go into building up the policy
session ... this means the API needs to change.

James


  reply	other threads:[~2018-10-22 15:55 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-22  7:33 [PATCH v4 0/7] add integrity and security to TPM2 transactions James Bottomley
2018-10-22  7:35 ` [PATCH v4 1/7] tpm-buf: create new functions for handling TPM buffers James Bottomley
2018-10-23 19:12   ` Jarkko Sakkinen
2018-10-23 19:16   ` Jarkko Sakkinen
2018-10-22  7:36 ` [PATCH v4 2/7] tpm2-sessions: Add full HMAC and encrypt/decrypt session handling James Bottomley
2018-10-22 22:19   ` Ard Biesheuvel
2018-10-23  7:01     ` James Bottomley
2018-10-23 10:08       ` Ard Biesheuvel
2018-10-24  8:40         ` Jarkko Sakkinen
2018-10-23 23:48   ` Jarkko Sakkinen
2018-10-24  9:31     ` James Bottomley
2018-10-25 15:56       ` Jarkko Sakkinen
2018-10-22  7:37 ` [PATCH v4 3/7] tpm2: add hmac checks to tpm2_pcr_extend() James Bottomley
2018-10-22  7:37 ` [PATCH v4 4/7] tpm2: add session encryption protection to tpm2_get_random() James Bottomley
2018-10-22  7:38 ` [PATCH v4 5/7] trusted keys: Add session encryption protection to the seal/unseal path James Bottomley
2018-10-24  0:03   ` Jarkko Sakkinen
2018-10-22  7:39 ` [PATCH v4 6/7] tpm: add the null key name as a tpm2 sysfs variable James Bottomley
2018-10-22  7:40 ` [PATCH v4 7/7] tpm2-sessions: NOT FOR COMMITTING add sessions testing James Bottomley
2018-10-22 13:53 ` [PATCH v4 0/7] add integrity and security to TPM2 transactions Ken Goldman
2018-10-22 14:18   ` James Bottomley
2018-10-22 15:50     ` Ken Goldman
2018-10-22 15:55       ` James Bottomley [this message]
2018-10-24  0:13     ` Jarkko Sakkinen
2018-10-24  7:41       ` James Bottomley
2018-10-25 15:39         ` Jarkko Sakkinen
2018-10-24  0:06   ` Jarkko Sakkinen
2018-10-24  7:34     ` James Bottomley
2018-10-25 16:53       ` Ken Goldman
2018-10-23 23:51 ` Jarkko Sakkinen
2018-10-24  7:43   ` James Bottomley
2018-10-25 15:42     ` Jarkko Sakkinen

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