On Wed, 2023-07-26 at 17:17 -0400, Eric Snowberg wrote:
> Commit 273df864cf746 ("ima: Check against blacklisted hashes for files with
> modsig") introduced an appraise_flag option for referencing the blacklist
> keyring. Any matching binary found on this keyring fails signature
> validation. This flag only works with module appended signatures.
>
> An important part of a PKI infrastructure is to have the ability to do
> revocation at a later time should a vulnerability be found. Expand the
> revocation flag usage to all appraisal functions. The flag is now
> enabled by default. Setting the flag with an IMA policy has been
> deprecated. Without a revocation capability like this in place, only
> authenticity can be maintained. With this change, integrity can now be
> achieved with digital signature based IMA appraisal.
>
> Signed-off-by: Eric Snowberg <eric.snowberg@xxxxxxxxxx>
> ---
> v4 changes:
> Fixed typo
> Also did some performance testing with this patch. With the associative array
> implementation used within the keyring code, there doesn't seem to be much of a
> difference between doing an appraisal with an empty blacklist keyring and one
> containing 1500 entries. At this time it is unknown how many entries a user
> would place in this keyring, but this seemed like a bigger number than most use
> cases. With the 1500 entries, there were only 7 lookups to get through the
> entire list for a file not contained within it. For something that was
> on the list, there was an average of 4 lookups and a single string compare.
> Based on this testing, IMHO, there could be a lot more entries added to the
> blacklist keyring without any real performance issues.
Thank you for the blacklist performance testing. The patch is now
queued in next-integrity-testing.
--
thanks,
Mimib
