On Thu, 2021-12-02 at 14:22 -0800, Eric Biggers wrote:

On Thu, Dec 02, 2021 at 04:55:05PM -0500, Mimi Zohar wrote:

quoted

Without the file signature included in the IMA measurement list, the type
of file digest is unclear.  Set up the plumbing to limit including
fs-verity's file digest in the IMA measurement list based on whether the
template name is ima-sig.  In the future, this could be relaxed to include
any template format that includes the file signature.

Does it make sense to tie IMA's fs-verity support to files having signatures?
What about IMA audit mode?  I thought that is just about collecting hashes, and
has nothing to do with signatures.

There's IMA-measurement, IMA-audit, and IMA-appraisal.  IMA-audit
refers to adding the file hash to the audit log record.  IMA-
measurement stores the collected hash in the IMA measurement list and
extends the TPM with the measurement, if there's a TPM.  Based on
policy, determines whether the file is measured, audited, and/or
appraised.  I actually do think it makes sense to require a signature,
but not necessarily enforce signature verification, in order to
differentiate the type of measurement being included in the measurement
list.

thanks,

Mimi