Re: [PATCH ghak25 v3 3/3] audit: add subj creds to NETFILTER_CFG record to cover async unregister

[Richard Guy Briggs]

On 2020-04-17 17:53, Paul Moore wrote:
> On Wed, Mar 18, 2020 at 5:33 PM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> > On 2020-03-18 17:22, Paul Moore wrote:
> > > On Wed, Mar 18, 2020 at 9:12 AM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> > > > On 2020-03-17 17:30, Richard Guy Briggs wrote:
> > > > > Some table unregister actions seem to be initiated by the kernel to
> > > > > garbage collect unused tables that are not initiated by any userspace
> > > > > actions.  It was found to be necessary to add the subject credentials to
> > > > > cover this case to reveal the source of these actions.  A sample record:
> > > > >
> > > > >   type=NETFILTER_CFG msg=audit(2020-03-11 21:25:21.491:269) : table=nat family=bridge entries=0 op=unregister pid=153 uid=root auid=unset tty=(none) ses=unset subj=system_u:system_r:kernel_t:s0 comm=kworker/u4:2 exe=(null)
> > > >
> > > > Given the precedent set by bpf unload, I'd really rather drop this patch
> > > > that adds subject credentials.
> > > >
> > > > Similarly with ghak25's subject credentials, but they were already
> > > > present and that would change an existing record format, so it isn't
> > > > quite as justifiable in that case.
> > >
> > > Your comments have me confused - do you want this patch (v3 3/3)
> > > considered for merging or no?
> >
> > I would like it considered for merging if you think it will be required
> > to provide enough information about the event that happenned.  In the
> > bpf unload case, there is a program number to provide a link to a
> > previous load action.  In this case, we won't know for sure what caused
> > the table to be unloaded if the number of entries was empty.  I'm still
> > trying to decide if it matters.  For the sake of caution I think it
> > should be included.  I don't like it, but I think it needs to be
> > included.
> 
> I'm in the middle of building patches 1/3 and 2/3, assuming all goes
> well I'll merge them into audit/next (expect mail soon), however I'm
> going back and forth on this patch.  Like you I kinda don't like it,
> and with both of us not in love with this patch I have to ask if there
> is certification requirement for this?  I know about the generic
> subj/obj requirements, but in the case where there is no associated
> task/syscall/etc. information it isn't like the extra fields supplied
> in this patch are going to have much information in that regard; it's
> really the *absence* of that information which is telling.  Which
> brings me to wonder if simply the lack of any associated records in
> this event is enough?  Before when we weren't associating records into
> a single event it would have been a problem, but the way things
> currently are, if there are no other records (and you have configured
> that) then I think you have everything you need to know.
> 
> Thoughts?

I'm good dropping that third patch, but Steve's perspective is more
authoritative here.

I'll respin patch 1/3 and 2/3 to fix the checkpatch.pl errors if you
prefer (was erroneously mentioned in ghak28 feedback).

> paul moore

- RGB

--
Richard Guy Briggs <rgb@xxxxxxxxxx>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635