linux-kernel - Re: [PATCH v7 2/2] tpm: add securityfs support for TPM 2.0 firmware event log

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Date:   Wed, 4 Jan 2017 15:01:18 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Nayna <nayna@...ux.vnet.ibm.com>
Cc:     tpmdd-devel@...ts.sourceforge.net, peterhuewe@....de,
        tpmdd@...horst.net, jgunthorpe@...idianresearch.com,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/2] tpm: add securityfs support for TPM 2.0 firmware
 event log

On Wed, Jan 04, 2017 at 02:08:06PM +0530, Nayna wrote:
> 
> 
> On 01/03/2017 07:03 PM, Jarkko Sakkinen wrote:
> > On Tue, Jan 03, 2017 at 01:09:18PM +0530, Nayna wrote:
> > > 
> > > 
> > > On 01/03/2017 03:42 AM, Jarkko Sakkinen wrote:
> > > > On Sun, Dec 11, 2016 at 12:35:33AM -0500, Nayna Jain wrote:
> > > > > Unlike the device driver support for TPM 1.2, the TPM 2.0 does
> > > > > not support the securityfs pseudo files for displaying the
> > > > > firmware event log.
> > > > > 
> > > > > This patch enables support for providing the TPM 2.0 event log in
> > > > > binary form. TPM 2.0 event log supports a crypto agile format that
> > > > > records multiple digests, which is different from TPM 1.2. This
> > > > > patch enables the tpm_bios_log_setup for TPM 2.0  and adds the
> > > > > event log parser which understand the TPM 2.0 crypto agile format.
> > > > > 
> > > > > Signed-off-by: Nayna Jain <nayna@...ux.vnet.ibm.com>
> > > > 
> > > > There is something fundamentally wrong in this commit.
> > > > 
> > > > You must not allow this feature unless CONFIG_OF is set. It is the only
> > > > interface where the supply path of the event log is well defined on
> > > > platforms that include a TPM 2.0 chip.
> > > 
> > > As per current implementation, if ACPI with TPM 2.0 doesn't support event
> > > log, tpm_read_log_acpi() is expected to return rc and tpm_bios_log_setup
> > > will not create securityfs. This is inline with our design for TPM 1.2 event
> > > log.
> > 
> > At minimum you must have a check for TPM_CHIP_FLAG_TPM2 in the beginning
> > of tpm_read_log_acpi. It is wrong to even try to open TCPA in this case.
> 
> Sure, will add this check and return -ENODEV if check passes.

Yeah, this is acceptable for me.

> Thanks & Regards,
>     - Nayna

/Jarkko