[dm-devel] [PATCH 7/7] dm: add documentation for IMA measurement support

[Mimi Zohar]

Hi Tushar, Mike,

On Mon, 2021-07-12 at 17:49 -0700, Tushar Sugandhi wrote:
> +Then IMA ASCII measurement log has the following format:
> +PCR TEMPLATE_DIGEST TEMPLATE ALG:EVENT_DIGEST EVENT_NAME EVENT_DATA
> +
> +PCR := Platform Configuration Register, in which the values are registered.
> +       This is applicable if TPM chip is in use.
> +TEMPLATE_DIGEST := Template digest of the IMA record.

^TEMPLATE_DATA_DIGEST

> +TEMPLATE := Template that registered the integrity value (e.g. ima-buf).

^TEMPLATE_NAME

The template data format consists of:
> +ALG:EVENT_DIGEST = Algorithm to compute event digest, followed by digest of event data
> +EVENT_NAME := Description of the event (e.g. 'table_load').
> +EVENT_DATA := The event data to be measured.

Missing from the document is a way of validating the template data. 
For example, in the original case of file measurements, the template
data contains the file hash, which can be recalculated or verified
against an allow list.

Other than re-calculating the template data digest based on the
template data, and verifying it against the template data digest in the
measurement list, would an attestation server be able to verify the
template data itself?

thanks,

Mimi