net/sched: cls_flower: Reject duplicated rules also under skip_sw

Currently, duplicated rules are rejected only for skip_hw or "none",
hence allowing users to push duplicates into HW for no reason.

Use the flower tables to protect for that.
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reported-by: Chris Mi <chrism@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_flower.c

@@ -1238,7 +1238,6 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 	if (err)
 		goto errout_idr;
 
-	if (!tc_skip_sw(fnew->flags)) {
 	if (!fold && fl_lookup(fnew->mask, &fnew->mkey)) {
 		err = -EEXIST;
 		goto errout_mask;
@@ -1248,7 +1247,6 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
 				     fnew->mask->filter_ht_params);
 	if (err)
 		goto errout_mask;
-	}
 
 	if (!tc_skip_hw(fnew->flags)) {
 		err = fl_hw_replace_filter(tp, fnew, extack);
@@ -1303,7 +1301,6 @@ static int fl_delete(struct tcf_proto *tp, void *arg, bool *last,
 	struct cls_fl_head *head = rtnl_dereference(tp->root);
 	struct cls_fl_filter *f = arg;
 
-	if (!tc_skip_sw(f->flags))
 	rhashtable_remove_fast(&f->mask->ht, &f->ht_node,
 			       f->mask->filter_ht_params);
 	__fl_delete(tp, f, extack);