The audit "context" and when to expect it.

[Paul Moore]

On Fri, May 29, 2020 at 5:42 PM Casey Schaufler <casey at schaufler-ca.com> wrote:
> On 5/29/2020 12:01 PM, Paul Moore wrote:
> > On Fri, May 29, 2020 at 1:59 PM Casey Schaufler <casey at schaufler-ca.com> wrote:
> >> What does a NULL audit context (e.g. ab->cxt == NULL) tell
> >> me about the status of the audit buffer? It seems like it should
> >> be telling me that the audit buffer is being created for some
> >> purpose unrelated to the current task. And yet there are places
> >> where information is pulled from the current task even when
> >> the cxt is NULL.
> > The simple answer is that a NULL audit_context indicates a standalone
> > record, meaning a record with a unique timestamp so that it is not
> > associated with any other records into an event.  If the audit_context
> > it not NULL then the information in the context is used to group, or
> > associate, all of the records sharing that context into a single
> > event.
>
> OK, so if I want a add a sub-record with the multiple secctx values

Terminology nit-pick: there are "records" and "events", there is
nothing we would call a sub-record.  In the case you are referring to,
this is a record which would always be part of a larger collection of
records.  It's similar to a PATH record in that it doesn't make sense
by itself, but when combined with the other records in an event, it
provides useful information.

> for the events that include a subject value I need to change those
> events to use an audit_context. Is that going to introduce an
> unacceptable memory or performance burden?

No more so than any additional record.  Or rather, it seems like this
is the only way to do what you want to do so I don't see a way around
it.

-- 
paul moore
www.paul-moore.com