Re: [PATCH v10 12/12] ima: Store the measurement again when appraising a modsig

Thiago Jung Bauermann
2019-05-28T19:14:48Z

Mimi Zohar <zohar@linux.ibm.com> writes:

> Hi Thiago,
>
> On Thu, 2019-04-18 at 00:51 -0300, Thiago Jung Bauermann wrote:
>> If the IMA template contains the "modsig" or "d-modsig" field, then the
>> modsig should be added to the measurement list when the file is appraised.
>>
>> And that is what normally happens, but if a measurement rule caused a file
>> containing a modsig to be measured before a different rule causes it to be
>> appraised, the resulting measurement entry will not contain the modsig
>> because it is only fetched during appraisal. When the appraisal rule
>> triggers, it won't store a new measurement containing the modsig because
>> the file was already measured.
>>
>> We need to detect that situation and store an additional measurement with
>> the modsig. This is done by adding an IMA_MEASURE action flag if we read a
>> modsig and the IMA template contains a modsig field.
>
> With the new per policy rule "template" support being added, this
> patch needs to be modified so that the per policy "template" format is
> checked. ima_template_has_modsig() should be called with the
> template_desc being used.

Right. Thanks for point out what needs to be done. After rebasing on top
of Matthew Garret's "IMA: Allow profiles to define the desired IMA
template" patch I changed ima_template_has_modsig() to check the
template_desc obtained from process_measurement().

--
Thiago Jung Bauermann
IBM Linux Technology Center