Re: [PATCH] audit: add fields to exclude filter by reusing user filter

[Richard Guy Briggs]

On 16/06/03, Paul Moore wrote:
> On Wed, Jun 1, 2016 at 6:50 PM, Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> > RFE: add additional fields for use in audit filter exclude rules
> > https://github.com/linux-audit/audit-kernel/issues/5
> >
> > Re-factor audit_filter_type() to use audit_filter_user_rules() to enable
> > exclude filter to additionally filter on PID, UID, GID, AUID,
> > LOGINUID_SET, SUBJ_*.
> >
> > Add check in audit_filter_user() to quit early if list is empty.
> >
> > Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> > ---
> >  kernel/auditfilter.c |   22 +++++++++-------------
> >  1 files changed, 9 insertions(+), 13 deletions(-)
> 
> I like the consolidation between audit_filter_type() and
> audit_filter_user(), I like it so much I think we should take it
> further.  Let's consolidate both functions into a single function (say
> audit_filter()?) and update the callers to use the new function.  This
> shouldn't be hard as the only callers are audit_receive_msg() and
> audit_log_start(); you'll need to be careful as the return values of
> the current functions are opposite of each other, but it should be
> easy enough to update one of the callers.
> 
> Sound reasonable?

Potentially...  I was even eyeing kernel/auditsc.c::audit_filter_rules()
for re-factoring...

> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index 96c9a1b..515c752 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -1358,6 +1358,9 @@ int audit_filter_user(int type)
> >         ret = 1; /* Audit by default */
> >
> >         rcu_read_lock();
> > +       if (list_empty(&audit_filter_list[AUDIT_FILTER_USER]))
> > +               goto unlock_and_return;
> > +
> >         list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
> >                 rc = audit_filter_user_rules(&e->rule, type, &state);
> >                 if (rc) {
> > @@ -1366,13 +1369,14 @@ int audit_filter_user(int type)
> >                         break;
> >                 }
> >         }
> > +unlock_and_return:
> >         rcu_read_unlock();
> > -
> >         return ret;
> >  }
> >
> >  int audit_filter_type(int type)
> >  {
> > +       enum audit_state state = AUDIT_DISABLED;
> >         struct audit_entry *e;
> >         int result = 0;
> >
> > @@ -1380,19 +1384,11 @@ int audit_filter_type(int type)
> >         if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
> >                 goto unlock_and_return;
> >
> > -       list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
> > -                               list) {
> > -               int i;
> > -               for (i = 0; i < e->rule.field_count; i++) {
> > -                       struct audit_field *f = &e->rule.fields[i];
> > -                       if (f->type == AUDIT_MSGTYPE) {
> > -                               result = audit_comparator(type, f->op, f->val);
> > -                               if (!result)
> > -                                       break;
> > -                       }
> > +       list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE], list) {
> > +               if (audit_filter_user_rules(&e->rule, type, &state) == 1) {
> > +                       result = 1;
> > +                       break;
> >                 }
> > -               if (result)
> > -                       goto unlock_and_return;
> >         }
> >  unlock_and_return:
> >         rcu_read_unlock();
> > --
> > 1.7.1
> >
> > --
> > Linux-audit mailing list
> > Linux-audit@xxxxxxxxxx
> > https://www.redhat.com/mailman/listinfo/linux-audit
> 
> 
> 
> -- 
> paul moore
> www.paul-moore.com

- RGB

--
Richard Guy Briggs <rgb@xxxxxxxxxx>
Kernel Security Engineering, Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635