linux-kernel - Re: [PATCH v2 0/3] tpm_pcr

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Date:   Thu, 4 May 2017 14:37:07 +0200
From:   Roberto Sassu <roberto.sassu@...wei.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
CC:     <tpmdd-devel@...ts.sourceforge.net>,
        <linux-ima-devel@...ts.sourceforge.net>,
        <linux-security-module@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/3] tpm_pcr_extend() code split

On 5/4/2017 11:24 AM, Jarkko Sakkinen wrote:
> On Wed, May 03, 2017 at 06:19:08PM +0200, Roberto Sassu wrote:
>> This patch set moves TPM 1.2 specific code to a new function called
>> tpm1_pcr_extend(). The purpose of splitting is to isolate TPM 2.0 code,
>> so that it can be more easily modified to handle multiple digests.
>>
>> With TPM 2.0, a Platform Configuration Register (PCR) could have multiple
>> values, stored in locations called banks. Each bank stores the values
>> of PCRs extended with the same hash algorithm.
>>
>> Currently, the TPM kernel driver does not take advantage of stronger
>> algorithms because PCRs are always extended with a SHA1 digest, padded
>> with zeros to match the length of the input for the hash algorithm
>> being used. Shortly after these patches, a new patch set will be provided
>> to allow callers of tpm_pcr_extend() to pass a digest for each algorithm
>> supported by the TPM.
>>
>> In this patch set, TPM 1.2 specific code will prepare the command buffer
>> with tpm_buf_init() which, in respect to the previous method, offers
>> protection against buffer overflow. Moreover, CPU native to big-endian
>> conversion has been removed from tags and ordinals definitions, as it is
>> already done by tpm_buf_init().
>>
>> Changelog:
>>
>> v2
>> - restored TPM_TAG_RQU_COMMAND definition in drivers/char/tpm/tpm.h
>> - removed endianness conversion in TPM_TAG_RQU_COMMAND definition
>> - removed '#include <linux/tpm_command.h>' in tpm-interface.c
>>   and tpm-sysfs.c
>> - restored TPM_ORD_ definitions in tpm-interface.c and tpm-sysfs.c
>>
>> Roberto Sassu (3):
>>   tpm: move endianness conversion of TPM_TAG_RQU_COMMAND to
>>     tpm_input_header
>>   tpm: move endianness conversion of ordinals to tpm_input_header
>>   tpm: move TPM 1.2 code of tpm_pcr_extend() to tpm1_pcr_extend()
>>
>>  drivers/char/tpm/tpm-interface.c | 79 ++++++++++++++++++++++------------------
>>  drivers/char/tpm/tpm-sysfs.c     |  6 +--
>>  drivers/char/tpm/tpm.h           |  2 +-
>>  3 files changed, 47 insertions(+), 40 deletions(-)
>
> Thanks for good quality patches! I'll test these but with quick skim
> no complains whatsoever :-)

Very good! We will see if it will be the same for the next patch set!

Roberto