cls_flower: Add extack support for src and dst port range options

Pass extack down to fl_set_key_port_range() and set message on error.

Both the min and max ports would qualify as invalid attributes here.
Report the min one as invalid, as it's probably what makes the most
sense from a user point of view.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_flower.c

@@ -738,7 +738,8 @@ static void fl_set_key_val(struct nlattr **tb,
 }
 
 static int fl_set_key_port_range(struct nlattr **tb, struct fl_flow_key *key,
-				 struct fl_flow_key *mask)
+				 struct fl_flow_key *mask,
+				 struct netlink_ext_ack *extack)
 {
 	fl_set_key_val(tb, &key->tp_range.tp_min.dst,
 		       TCA_FLOWER_KEY_PORT_DST_MIN, &mask->tp_range.tp_min.dst,
@@ -753,13 +754,22 @@ static int fl_set_key_port_range(struct nlattr **tb, struct fl_flow_key *key,
 		       TCA_FLOWER_KEY_PORT_SRC_MAX, &mask->tp_range.tp_max.src,
 		       TCA_FLOWER_UNSPEC, sizeof(key->tp_range.tp_max.src));
 
-	if ((mask->tp_range.tp_min.dst && mask->tp_range.tp_max.dst &&
+	if (mask->tp_range.tp_min.dst && mask->tp_range.tp_max.dst &&
 	    htons(key->tp_range.tp_max.dst) <=
-		 htons(key->tp_range.tp_min.dst)) ||
-	    (mask->tp_range.tp_min.src && mask->tp_range.tp_max.src &&
+	    htons(key->tp_range.tp_min.dst)) {
+		NL_SET_ERR_MSG_ATTR(extack,
+				    tb[TCA_FLOWER_KEY_PORT_DST_MIN],
+				    "Invalid destination port range (min must be strictly smaller than max)");
+		return -EINVAL;
+	}
+	if (mask->tp_range.tp_min.src && mask->tp_range.tp_max.src &&
 	    htons(key->tp_range.tp_max.src) <=
-		 htons(key->tp_range.tp_min.src)))
+	    htons(key->tp_range.tp_min.src)) {
+		NL_SET_ERR_MSG_ATTR(extack,
+				    tb[TCA_FLOWER_KEY_PORT_SRC_MIN],
+				    "Invalid source port range (min must be strictly smaller than max)");
 		return -EINVAL;
+	}
 
 	return 0;
 }
@@ -1402,7 +1412,7 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
 	if (key->basic.ip_proto == IPPROTO_TCP ||
 	    key->basic.ip_proto == IPPROTO_UDP ||
 	    key->basic.ip_proto == IPPROTO_SCTP) {
-		ret = fl_set_key_port_range(tb, key, mask);
+		ret = fl_set_key_port_range(tb, key, mask, extack);
 		if (ret)
 			return ret;
 	}