Re: [PATCH 0/3] support for duplicate measurement of integrity critical data

[Mimi Zohar]

Hi Tushar,

On Fri, 2021-01-29 at 16:45 -0800, Tushar Sugandhi wrote:
> IMA does not measure duplicate buffer data since TPM extend is a very
> expensive operation.  However, in some cases for integrity critical
> data, the measurement of duplicate data is necessary to accurately
> determine the current state of the system.  Eg, SELinux state changing
> from 'audit', to 'enforcing', and back to 'audit' again.  In this
> example, currently, IMA will not measure the last state change to
> 'audit'.  This limits the ability of attestation services to accurately
> determine the current state of the integrity critical data on the
> system.
> 
> This series addresses this gap by providing the ability to measure
> duplicate entries for integrity critical data, driven by policy.

The same reason for re-measuring buffer data is equally applicable to
files.  In both cases, the file or the buffer isn't re-measured if it
already exists in the htable.   Please don't limit this patch set to
just buffer data.

thanks,

Mimi