Re: [PATCH v6 0/2] enhance TPM 2.0 extend function to support multiple PCR banks

[Nayna]

On 01/26/2017 02:15 AM, Jarkko Sakkinen wrote:
> On Fri, Jan 20, 2017 at 12:05:11PM -0500, Nayna Jain wrote:
> > IMA extends its hash measurements in the TPM PCRs, based on policy.
> > The existing in-kernel TPM extend function extends only the SHA1
> > PCR bank. TPM 2.0 defines multiple PCR banks, to support different
> > hash algorithms. The TCG TPM 2.0 Specification[1] recommends
> > extending all active PCR banks to prevent malicious users from
> > setting unused PCR banks with fake measurements and quoting them.
> > This patch set adds support for extending all active PCR banks,
> > as recommended.
> >
> > The first patch implements the TPM 2.0 capability to retrieve
> > the list of active PCR banks.
> >
> > The second patch modifies the tpm_pcr_extend() and tpm2_pcr_extend()
> > interface to support extending multiple PCR banks. The existing
> > tpm_pcr_extend() interface expects only a SHA1 digest. Hence, to
> > extend all active PCR banks with differing digest sizes for TPM 2.0,
> > the SHA1 digest is padded with 0's as needed.
> >
> > [1] TPM 2.0 Specification referred here is "TCG PC Client Specific
> > Platform Firmware Profile for TPM 2.0"
>
> I pushed these patches. I had to resolve merge conflicts caused
> by the min_rsp_body_length parameter in tpm_transmit_cmd. Can you
> verify that I didn't break anything?

Thanks Jarkko !!

Yes, it looks fine, also tested with it.

Just to understand..in tpm2_get_pcr_allocation(), how did you decide 
min_rsp_body_length to be 9.
If I understood correctly, I think it is the size after header, till 
last fixed parameter i.e.  till count.
Is the assumption is that count can be zero, such that there is no 
active bank for PCR and so no struct tpm2_pcr_selection ?

Thanks & Regards,
   - Nayna

> /Jarkko
>
> > Changelog v6:
> > - Patch "tpm: implement TPM 2.0 capability to get active PCR banks"
> >    - Fixed the regression - missing tpm_buf_destroy() in
> >    in tpm2_get_pcr_allocation(). Thanks Jarkko for noticing.
> >    - Added TPM2_ALG_ERROR = 0x0000 to represent invalid algorithm.
> >
> > Changelog v5:
> > - Patch "tpm: implement TPM 2.0 capability to get active PCR banks"
> >   - Included Jarkko's feedbacks
> >     - Moved variable declaration to start of function in
> >     tpm_pcr_extend()
> >
> >
> > Changelog v4:
> > - Updated cover letter as per Mimi's feedback.
> > - Rebased to Jarkko's latest master branch (4064b6b tpm_tis: use
> >    default timeout value if chip reports it as zero)
> > - Patch "tpm: implement TPM 2.0 capability to get active PCR banks"
> >   - Included Jarkko's feedbacks
> >     - Moved call to tpm2_get_pcr_allocation to Patch 2
> >     - Renamed struct tpm2_tpms_pcr_selection to struct tpm2_pcr_selection
> >     and moved the struct to before tpm2_get_pcr_allocation()
> >     - Fixed code formatting
> > - Patch "tpm: enchance TPM 2.0 PCR extend to support multiple banks"
> >   - Included Jarkkos' feedbacks
> >     - Updated commit msg to mention dependency on CRYPTO_HASH_INFO
> >     - Renamed struct tpmt_hash to struct tpm2_digest
> >     - Removed struct tpml_digest_values, tpm2_pcr_extend() now accepts
> >     count and digests list as two separate arguments. Added check for
> >     count of hashes passed.
> >   - Cleaned up struct tpm2_pcr_extend_in as not required anymore with
> >   use of tpm_buf
> >   - Moved struct tpm2_null_auth_area just before tpm2_pcr_extend() as
> >   it is the only function using it for now.
> >   - Fixed code formatting
> >
> > Changelog v3:
> > - Rebased to the Jarkko's latest master branch (8e25809 tpm:
> >    Do not print an error message when doing TPM auto startup)
> > - Patch "tpm: implement TPM 2.0 capability to get active PCR banks"
> >    - Included Jarkko's feedbacks
> >       - Removed getcap_in, getcap_out and used tpm_buf for getting
> >       capability.
> >       - Used ARRAY_SIZE in place of TPM_MAX_PCR_BANKS and included
> >       other feedbacks.
> > - Patch "tpm: enhance TPM 2.0 PCR extend to support multiple banks"
> >       - Fixed kbuild errors
> >         - Fixed buf.data uninitialized warning.
> >         - Added TCG_TPM dependency on CONFIG_CRYPTO_HASH_INFO in Kconfig.
> >
> > Changelog v2:
> >
> > - Patch "tpm: implement TPM 2.0 capability to get active PCR banks"
> >    - defined structs definition in tpm2-cmd.c.
> >    - no_of_active_banks field is removed. Instead, constant
> >    TPM2_MAX_PCR_BANKS is defined.
> >    - renamed tpm2_get_active_pcr_banks() to tpm2_get_pcr_allocation()
> >    - removed generic function tpm2_get_capability().
> >
> > - Patch "tpm: enchance TPM 2.0 PCR extend to support multiple banks"
> >   - Removed tpm2.h, and defined structs common for extend and event log
> >    in tpm_eventlog.h
> >   - uses tpm_buf in tpm2_pcr_extend().
> >
> > Nayna Jain (2):
> >    tpm: implement TPM 2.0 capability to get active PCR banks
> >    tpm: enhance TPM 2.0 PCR extend to support multiple banks
> >
> >   drivers/char/tpm/Kconfig         |   1 +
> >   drivers/char/tpm/tpm-interface.c |  15 +++-
> >   drivers/char/tpm/tpm.h           |   8 ++-
> >   drivers/char/tpm/tpm2-cmd.c      | 150 ++++++++++++++++++++++++++++-----------
> >   drivers/char/tpm/tpm_eventlog.h  |   7 ++
> >   5 files changed, 137 insertions(+), 44 deletions(-)
> >
> > --
> > 2.5.0
> >
> > --
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