[PATCH v2] ima: export the measurement list when needed

[Mimi Zohar]

On Thu, 2020-02-13 at 08:41 +0200, Janne Karhunen wrote:
> On Thu, Feb 13, 2020 at 3:03 AM Mimi Zohar <zohar at linux.ibm.com> wrote:
> 
> > > This is a pretty important new feature.
> > > A lot of people can't use IMA because of the memory issue.
> > > Also, I really think we need to let administrators choose the tradeoffs
> > > of keeping the list in memory, on a local file, or only on the
> > > attestation server, as best fits their use cases.
> >
> > Dave, I understand that some use cases require the ability of
> > truncating the measurement list.  We're discussing how to truncate the
> > measurement list.  For example, in addition to the existing securityfs
> > binary_runtime_measurements file, we could define a new securityfs
> > file indicating the number of records to delete.
> 
> I don't have strong opinions either way, just let me know how to adapt
> the patch and we will get it done asap. I'd prefer a solution where
> the kernel can initiate the flush, but if not then not.

If the measurement list isn't stored in kernel memory, then we would
have the best of both worlds.  The measurement list staying intact for
attestation, with userspace's ability to truncate the measurement list
as desired.  Barring any implementation details, I see this as a win-
win solution.

Mimi