Re: [PATCH ghak124 v3] audit: log nftables configuration change events

Hi, On Thu, Feb 11, 2021 at 04:02:55PM -0500, Steve Grubb wrote: > On Thursday, February 11, 2021 11:29:34 AM EST Paul Moore wrote: > > > If I'm not mistaken, iptables emits a single audit log per table, ipset > > > doesn't support audit at all. So I wonder how much audit logging is > > > required at all (for certification or whatever reason). How much > > > granularity is desired? > > <snip> > > > I believe the netfilter auditing was mostly a nice-to-have bit of > > functionality to help add to the completeness of the audit logs, but I > > could very easily be mistaken. Richard put together those patches, he > > can probably provide the background/motivation for the effort. > > There are certifications which levy requirements on information flow control. > The firewall can decide if information should flow or be blocked. Information > flow decisions need to be auditable - which we have with the audit target. In nftables, this is realized via 'log level audit' statement. Functionality should by all means be identical to that of xtables' AUDIT target. > That then swings in requirements on the configuration of the information flow > policy. > > The requirements state a need to audit any management activity - meaning the > creation, modification, and/or deletion of a "firewall ruleset". Because it > talks constantly about a ruleset and then individual rules, I suspect only 1 > summary event is needed to say something happened, who did it, and the > outcome. This would be in line with how selinux is treated: we have 1 summary > event for loading/modifying/unloading selinux policy. So the central element are firewall rules for audit purposes and NETFILTER_CFG notifications merely serve asserting changes to those rules are noticed by the auditing system. Looking at xtables again, this seems coherent: Any change causes the whole table blob to be replaced (while others stay in place). So table replace/create is the most common place for a change notification. In nftables, the most common one is generation dump - all tables are treated as elements of the same ruleset, not individually like in xtables. Richard, assuming the above is correct, are you fine with reducing nftables auditing to a single notification per transaction then? I guess Florian sufficiently illustrated how this would be implemented.

> Hope this helps... It does, thanks a lot for the information! Thanks, Phil