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 14:08:06 +0530
From:   Nayna <nayna@...ux.vnet.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.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 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.

Thanks & Regards,
     - Nayna

>
> /Jarkko
>