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Subject: Re: [PATCH v2] KEYS: trusted: allow module init if TPM is inactive or
 deactivated
From:   Roberto Sassu <roberto.sassu@huawei.com>
To:     Tyler Hicks <tyhicks@canonical.com>
CC:     <jarkko.sakkinen@linux.intel.com>, <jejb@linux.ibm.com>,
        <zohar@linux.ibm.com>, <jgg@ziepe.ca>,
        <linux-integrity@vger.kernel.org>,
        <linux-security-module@vger.kernel.org>,
        <keyrings@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <crazyt2019+lml@gmail.com>, <nayna@linux.vnet.ibm.com>,
        <silviu.vlasceanu@huawei.com>
References: <20190802150733.1972-1-roberto.sassu@huawei.com>
 <20190802153030.GB26616@elm>
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Message-ID: <8baf1c39-ad04-5cd6-bc67-341e7411db16@huawei.com>
Date:   Fri, 2 Aug 2019 18:11:09 +0200
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On 8/2/2019 5:34 PM, Roberto Sassu wrote:
> On 8/2/2019 5:30 PM, Tyler Hicks wrote:
>> On 2019-08-02 17:07:33, Roberto Sassu wrote:
>>> Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize 
>>> w/o a
>>> TPM") allows the trusted module to be loaded even a TPM is not found to
>>                                                     ^ if
>>
>>> avoid module dependency problems.
>>>
>>> However, trusted module initialization can still fail if the TPM is
>>> inactive or deactivated. This patch ignores tpm_get_random() errors in
>>> init_digests() and returns -EFAULT in pcrlock() if the TPM didn't return
>>> random data.
>>>
>>> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
>>
>> The code changes look correct to me.
>>
>>    Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
>>
>> For whoever takes this patch through their tree, I think that adding the
>> following Fixes tag would be useful (as well as cc'ing stable):
>>
>>    Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip 
>> structure...")
>>
>> I think it is also worth leaving a short note, in the commit message,
>> for backporters that commit 782779b60faa ("tpm: Actually fail on TPM
>> errors during "get random"") should be included with any backports of
>> this patch.
> 
> Right, thanks. I wait for Jarkko's comments and I add both the Fixes tag
> and the short note in the next version of the patch.

Uhm, I was thinking that maybe it is not necessary to mention commit
782779b60faa. This patch would still return 0 even if that commit is not
backported (TPM_ERR_DISABLED < TPM_MAX_DIGEST_SIZE).

Roberto

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