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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Roberto Sassu <roberto.sassu@huawei.com>
Cc: zohar@linux.ibm.com, david.safford@ge.com, monty.wiseman@ge.com,
	linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, silviu.vlasceanu@huawei.com
Subject: Re: [PATCH v6 7/7] tpm: pass an array of tpm_bank_list structures to tpm_pcr_extend()
Date: Fri, 14 Dec 2018 09:58:52 +0200	[thread overview]
Message-ID: <20181214075852.GB1721@linux.intel.com> (raw)
In-Reply-To: <ae012b83-af66-6dfe-6131-e08507c3372e@huawei.com>

On Thu, Dec 13, 2018 at 08:57:17AM +0100, Roberto Sassu wrote:
> > 1. The function does not fail if alg_id is not found. This will go
> >     silent.
> 
> It is intentional. If alg_id is not found, the PCR is extended with the
> first digest passed by the caller of tpm_pcr_extend(). If no digest was
> provided, the PCR is extended with 0s. This is done to prevent that
> PCRs in unused banks are extended later with fake measurements.
> 
> 
> > 2. The function does not fail if there is a mismatch with the digest
> >     sizes.
> 
> The data passed by the caller of tpm_pcr_extend() is copied to
> dummy_hash, which has the maximum length. Then, tpm2_pcr_extend() takes
> from dummy_hash as many bytes as needed, depending on the current
> algorithm.

I would suggest to document these corner cases to the function long
description to make it easy and obvious to understand.

/Jarkko

  reply	other threads:[~2018-12-14  7:59 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-04  8:21 [PATCH v6 0/7] tpm: retrieve digest size of unknown algorithms from TPM Roberto Sassu
2018-12-04  8:21 ` [PATCH v6 1/7] tpm: dynamically allocate the allocated_banks array Roberto Sassu
2018-12-04 23:18   ` Jarkko Sakkinen
2018-12-06 17:56     ` Roberto Sassu
2018-12-12 18:32       ` Jarkko Sakkinen
2018-12-13  8:14         ` Roberto Sassu
2018-12-11 21:01     ` Ken Goldman
2018-12-04  8:21 ` [PATCH v6 2/7] tpm: add _head suffix to tcg_efi_specid_event and tcg_pcr_event2 Roberto Sassu
2018-12-04 23:26   ` Jarkko Sakkinen
2018-12-09 12:10   ` Nayna Jain
2018-12-04  8:21 ` [PATCH v6 3/7] tpm: rename and export tpm2_digest and tpm2_algorithms Roberto Sassu
2018-12-04  8:21 ` [PATCH v6 4/7] tpm: modify tpm_pcr_read() definition to pass a TPM hash algorithm Roberto Sassu
2018-12-04 23:40   ` Jarkko Sakkinen
2018-12-05 20:31     ` Mimi Zohar
2018-12-06 19:49       ` Mimi Zohar
2018-12-07 14:51         ` Roberto Sassu
2018-12-09 20:32           ` Mimi Zohar
2018-12-10  7:55             ` Roberto Sassu
2018-12-06  8:14     ` Nayna Jain
2018-12-12 18:29       ` Jarkko Sakkinen
2018-12-09 12:04     ` Nayna Jain
2018-12-04  8:21 ` [PATCH v6 5/7] tpm: retrieve digest size of unknown algorithms with PCR read Roberto Sassu
2018-12-04 23:53   ` Jarkko Sakkinen
2018-12-06 18:00     ` Roberto Sassu
2018-12-12 18:16       ` Jarkko Sakkinen
2018-12-04  8:21 ` [PATCH v6 6/7] tpm: ensure that the output of PCR read contains the correct digest size Roberto Sassu
2018-12-05  0:09   ` Jarkko Sakkinen
2018-12-05  0:46     ` Jarkko Sakkinen
2018-12-06 18:07       ` Roberto Sassu
2018-12-12 18:18         ` Jarkko Sakkinen
2018-12-04  8:21 ` [PATCH v6 7/7] tpm: pass an array of tpm_bank_list structures to tpm_pcr_extend() Roberto Sassu
2018-12-05  0:14   ` Jarkko Sakkinen
2018-12-06 18:09     ` Roberto Sassu
2018-12-12 18:25       ` Jarkko Sakkinen
2018-12-06 18:38     ` Roberto Sassu
2018-12-12 18:27       ` Jarkko Sakkinen
2018-12-13  7:57         ` Roberto Sassu
2018-12-14  7:58           ` Jarkko Sakkinen [this message]
2018-12-05  0:21 ` [PATCH v6 0/7] tpm: retrieve digest size of unknown algorithms from TPM Jarkko Sakkinen
2018-12-05  0:23   ` Jarkko Sakkinen

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