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

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Date:   Thu, 4 May 2017 20:37:21 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Roberto Sassu <roberto.sassu@...wei.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 Thu, May 04, 2017 at 12:24:47PM +0300, 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 :-)

1/3 and 2/3 are now applied to master and next (which will be pulled to
linux-next).

/Jarkko