Re: [PATCH] audit: set TIF_AUDIT_SYSCALL only if audit filter has been populated
On Wed, Mar 14, 2018 at 12:28 AM, Jiri Kosina <jikos(a)kernel.org> wrote:
On Wed, 14 Mar 2018, Andy Lutomirski wrote:
> > Yes...I wished I was in on the beginning of this discussion. Here's the
> > problem. We need all tasks auditable unless specifically dismissed as
> > uninteresting. This would be a task,never rule.
> >
> > The way we look at it, is if it boots with audit=1, then we know auditd
> > is expected to run at some point. So, we need all tasks to stay
> > auditable. If they weren't and auditd enabled auditing, then we'd need
> > to walk the whole proctable and stab TIF_AUDIT_SYSCALL into every
> > process in the system. It was decided that this is too ugly.
>
> When was that decided? That's what this patch does.
I'd like to see some more justification as well.
Namely, if I compare "setting TIF_AUDIT_SYSCALL for every process on a
need-to-be-so basis" to "we always go through the slow path and
pessimistically assume that audit is enabled and has reasonable ruleset
loaded", I have my own (different) opinion of what is too ugly.
Me too.
That being said, on re-review of my old code, I think that
audit_dec_n_rules() may be the wrong approach. It may be better to
leave TIF_AUDIT_SYSCALL set but to make the audit code itself clear
the flag the next time through. That way we don't end up with a
partially filled in syscall audit record that never gets consumed if
we clear TIF_AUDIT_SYSCALL in the middle of a syscall.