Re: [Linux-ima-devel] [PATCH v2 4/5] keys, trusted: modify arguments of tpm_pcr_extend()

From	Roberto Sassu <roberto.sassu@huawei.com>
Newsgroups	linux.kernel
Subject	Re: [Linux-ima-devel] [PATCH v2 4/5] keys, trusted: modify arguments of tpm_pcr_extend()
Date	2017-05-30 15:50 +0200
Message-ID	<tMPH4-82d-15@gated-at.bofh.it> (permalink)
References	<tDMp3-2VD-3@gated-at.bofh.it> <tDMp4-2VD-7@gated-at.bofh.it> <tMGaJ-1y5-1@gated-at.bofh.it> <tMJV0-4hz-35@gated-at.bofh.it> <tMO8i-7b8-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 5/30/2017 2:06 PM, Mimi Zohar wrote:
> On Tue, 2017-05-30 at 09:36 +0200, Roberto Sassu wrote:
>> On 5/30/2017 5:35 AM, Mimi Zohar wrote:
>>> On Fri, 2017-05-05 at 16:21 +0200, Roberto Sassu wrote:
>>>> pcrlock() has been modified to pass the correct arguments
>>>> to tpm_pcr_extend(): the pointer of a tpm2_digest structure containing
>>>> a random value generated by tpm_get_random() and the size of the array (1).
>>>
>>> If the number of arguments is wrong, that means the patch that
>>> introduced the change is not bi-sect safe.  (This comment is
>>> applicable to patch 5/5 too.)
>>
>> Jarkko (the TPM driver maintainer) asked me to not introduce
>> a new function to pass multiple digests, but to modify
>> the parameters of tpm_pcr_extend().
>
> Since struct tpm2_digest is a static size, shouldn't we be able to
> compute the number of digests?

The length of 'hash' is not passed to tpm_pcr_extend().

The only way to avoid changing the number of parameters would
be to pass a buffer whose format is the same of the event log
format defined by TCG:

<algo count> <algo1 ID> <digest1> ... <algoN ID> <digestN>

Roberto

-- 
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Bo PENG, Qiuen PENG, Shengli WANG

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Re: [Linux-ima-devel] [PATCH v2 4/5] keys,     trusted: modify  arguments of tpm_pcr_extend() Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-05-30 05:40 +0200
  Re: [Linux-ima-devel] [PATCH v2 4/5] keys, trusted: modify arguments  of tpm_pcr_extend() Roberto Sassu <roberto.sassu@huawei.com> - 2017-05-30 09:40 +0200
    Re: [Linux-ima-devel] [PATCH v2 4/5] keys, trusted: modify  arguments of tpm_pcr_extend() Mimi Zohar <zohar@linux.vnet.ibm.com> - 2017-05-30 14:10 +0200
      Re: [Linux-ima-devel] [PATCH v2 4/5] keys, trusted: modify arguments  of tpm_pcr_extend() Roberto Sassu <roberto.sassu@huawei.com> - 2017-05-30 15:50 +0200

csiph-web