linux-kernel - Re: [PATCH v3] tpm: Add Upgrade/Reduced mode support for TPM2 modules

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Message-ID: <d6cd1eb6-48b5-c1ad-e063-a26bc7509d95@axis.com>
Date:   Fri, 6 Aug 2021 16:20:56 +0200
From:   Borys Movchan <borysmn@...s.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Borys Movchan <Borys.Movchan@...s.com>
CC:     Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
        kernel <kernel@...s.com>,
        "linux-integrity@...r.kernel.org" <linux-integrity@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] tpm: Add Upgrade/Reduced mode support for TPM2 modules


On 8/5/21 10:52 PM, Jarkko Sakkinen wrote:
> On Wed, Aug 04, 2021 at 06:21:31PM +0200, Borys Movchan wrote:
>> If something went wrong during the TPM firmware upgrade, like power
>> failure or the firmware image file get corrupted, the TPM might end
>> up in Upgrade or Failure mode upon the next start. The state is
>> persistent between the TPM power cycle/restart.
>>
>> According to TPM specification:
>>  * If the TPM is in Upgrade mode, it will answer with TPM2_RC_UPGRADE
>>    to all commands except Field Upgrade related ones.
>>  * If the TPM is in Failure mode, it will allow performing TPM
>>    initialization but will not provide any crypto operations.
>>    Will happily respond to Field Upgrade calls.
>>
>> The fix changes the behavior of the `tpm2_auto_startup` function, so
>                                 
> In commit messages, you ought to use imperative form:
>
> "Change the behaviour of tpm2_auto_startup(), ..."
>
Done
>> it tries to detect what mode TPM is running in. If the chip is in the
>> Upgrade or Failure mode, the function returns -EIO error code which
>> can be used later to adjust driver behavior later.
> *How* tpm2_auto_startup() detects the mode?
Done
>> After `tpm_chip_register` calls `tpm2_auto_startup` it checks for the
> Please remove all these hyphens. They make the commit message a pain
> to read. E.g. instead write tpm_chip_register(). This is not Github.
Done
>> error code. If the TPM is in Upgrade or Failure mode, set the
>> `limited_mode` flag. The calls to `tpm2_get_cc_attrs_tbl`,
>> `tpm_add_hwrng` and `tpm_get_pcr_allocation` will fail if the TPM is
>> in Failure or Upgrade mode, so use `limited_mode` flag to exclude
>> them from the module initialization sequence.
>>
>> Signed-off-by: Borys Movchan <borysmn@...s.com>
>> ---
>>
>> Notes:
>>     Commit message updated
> v2:
> * Commit message updated.
>
> Notes would be something that had existed already in the first version.
> Here we want a simple change log.
Corrected
> /Jarkko
>

Kind regards,

Borys