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Subject: Re: [PATCH v9 5/8] ima: make process_buffer_measurement() generic
To:     Nayna Jain <nayna@linux.vnet.ibm.com>,
        Nayna Jain <nayna@linux.ibm.com>, linuxppc-dev@ozlabs.org,
        linux-efi@vger.kernel.org, linux-integrity@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Jeremy Kerr <jk@ozlabs.org>,
        Matthew Garret <matthew.garret@nebula.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Claudio Carvalho <cclaudio@linux.ibm.com>,
        George Wilson <gcwilson@linux.ibm.com>,
        Elaine Palmer <erpalmer@us.ibm.com>,
        Eric Ricther <erichte@linux.ibm.com>,
        Oliver O'Halloran <oohall@gmail.com>,
        Prakhar Srivastava <prsriva02@gmail.com>
References: <20191024034717.70552-1-nayna@linux.ibm.com>
 <20191024034717.70552-6-nayna@linux.ibm.com>
 <1ae56786-4d5c-ba8e-e30c-ced1e15ccb9c@linux.microsoft.com>
 <24cf44d5-a1f0-f59e-9884-c026b1ee2d3b@linux.vnet.ibm.com>
From:   Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Message-ID: <8a97301a-0e25-2718-bd81-d778cb58e1d3@linux.microsoft.com>
Date:   Fri, 25 Oct 2019 10:32:53 -0700
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On 10/25/2019 10:24 AM, Nayna Jain wrote:
> 
> On 10/24/19 10:20 AM, Lakshmi Ramasubramanian wrote:
>> On 10/23/19 8:47 PM, Nayna Jain wrote:
>>
>> Hi Nayna,
>>
>>> +void process_buffer_measurement(const void *buf, int size,
>>> +                const char *eventname, enum ima_hooks func,
>>> +                int pcr)
>>>   {
>>>       int ret = 0;
>>>       struct ima_template_entry *entry = NULL;
>>
>>> +    if (func) {
>>> +        security_task_getsecid(current, &secid);
>>> +        action = ima_get_action(NULL, current_cred(), secid, 0, func,
>>> +                    &pcr, &template);
>>> +        if (!(action & IMA_MEASURE))
>>> +            return;
>>> +    }
>>
>> In your change set process_buffer_measurement is called with NONE for 
>> the parameter func. So ima_get_action (the above if block) will not be 
>> executed.
>>
>> Wouldn't it better to update ima_get_action (and related functions) to 
>> handle the ima policy (func param)?
> 
> 
> The idea is to use ima-buf template for the auxiliary measurement 
> record. The auxiliary measurement record is an additional record to the 
> one already created based on the existing policy. When func is passed as 
> NONE, it represents it is an additional record. I am not sure what you 
> mean by updating ima_get_action, it is already handling the ima policy.
>

I was referring to using "func" in process_buffer_measurement to 
determine ima action. In my opinion, process_buffer_measurement should 
be generic.

ima_get_action() should instead determine the required ima action, 
template, pcr, etc. based on "func" passed to it.

thanks,
  -lakshmi