Re: [PATCH v2 0/3] tpm_pcr_extend() code split

From: Roberto Sassu
Date: Thu May 04 2017 - 08:37:45 EST

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().


- 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: 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!