linux-kernel - Re: [tpmdd-devel] [PATCH v6 0/2] enhance TPM 2.0 extend function to support multiple PCR banks

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Date:   Thu, 26 Jan 2017 00:57:45 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stefan Berger <stefanb@...ux.vnet.ibm.com>
Cc:     Nayna Jain <nayna@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net
Subject: Re: [tpmdd-devel] [PATCH v6 0/2] enhance TPM 2.0 extend function to
 support multiple PCR banks

On Thu, Jan 26, 2017 at 12:52:52AM +0200, Jarkko Sakkinen wrote:
> On Thu, Jan 26, 2017 at 12:04:01AM +0200, Jarkko Sakkinen wrote:
> > On Wed, Jan 25, 2017 at 04:08:55PM -0500, Stefan Berger wrote:
> > > On 01/25/2017 03:45 PM, 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?
> > > 
> > > It looks like this hunk here got into the wrong patch:
> > > 
> > > @@ -1061,7 +1068,7 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> > >         tpm_buf_append_u32(&buf, 0);
> > >         tpm_buf_append_u32(&buf, 1);
> > > 
> > > -       rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, 0,
> > > +       rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, 9, 0,
> > >                               "get tpm pcr allocation");
> > >         if (rc < 0)
> > >                 goto out;
> > 
> > Thanks. I'll eventually fix this before sending the next pull request.
> 
> I'll actually squash the patches and make it a static function. Its
> only call site is tpm2_auto_startup and remove the declaration from
> tpm.h. There's no point to have it there.

OK, now it should be better. I also moved tpm2_digest to tpm.h as it is
part of the API.

/Jarkko