bridge: add per-port broadcast flood flag

Support for l2 multicast flood control was added in commit b6cb5ac8331b
("net: bridge: add per-port multicast flood flag"). It allows broadcast
as it was introduced specifically for unknown multicast flood control.
But as broadcast is a special case of multicast, this may also need to
be disabled. For this purpose, introduce a flag to disable the flooding
of received l2 broadcasts. This approach is backwards compatible and
provides flexibility in filtering for the desired packet types.

Cc: Nikolay Aleksandrov <[e-mail]>
Signed-off-by: Mike Manning <[e-mail]>
Reviewed-by: Nikolay Aleksandrov <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/linux/if_bridge.h

···
 #define BR_MCAST_FLOOD		BIT(11)
 #define BR_MULTICAST_TO_UNICAST	BIT(12)
 #define BR_VLAN_TUNNEL		BIT(13)
+#define BR_BCAST_FLOOD		BIT(14)
 
 #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
 

include/uapi/linux/if_link.h

···
 	IFLA_BRPORT_MCAST_FLOOD,
 	IFLA_BRPORT_MCAST_TO_UCAST,
 	IFLA_BRPORT_VLAN_TUNNEL,
+	IFLA_BRPORT_BCAST_FLOOD,
 	__IFLA_BRPORT_MAX
 };
 #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)

net/bridge/br_forward.c

···
 	struct net_bridge_port *p;
 
 	list_for_each_entry_rcu(p, &br->port_list, list) {
-		/* Do not flood unicast traffic to ports that turn it off */
-		if (pkt_type == BR_PKT_UNICAST && !(p->flags & BR_FLOOD))
-			continue;
-		/* Do not flood if mc off, except for traffic we originate */
-		if (pkt_type == BR_PKT_MULTICAST &&
-		    !(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
-			continue;
+		/* Do not flood unicast traffic to ports that turn it off, nor
+		 * other traffic if flood off, except for traffic we originate
+		 */
+		switch (pkt_type) {
+		case BR_PKT_UNICAST:
+			if (!(p->flags & BR_FLOOD))
+				continue;
+			break;
+		case BR_PKT_MULTICAST:
+			if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
+				continue;
+			break;
+		case BR_PKT_BROADCAST:
+			if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
+				continue;
+			break;
+		}
 
 		/* Do not flood to ports that enable proxy ARP */
 		if (p->flags & BR_PROXYARP)

net/bridge/br_if.c

···
 	p->path_cost = port_cost(dev);
 	p->priority = 0x8000 >> BR_PORT_BITS;
 	p->port_no = index;
-	p->flags = BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD;
+	p->flags = BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD | BR_BCAST_FLOOD;
 	br_init_port(p);
 	br_set_state(p, BR_STATE_DISABLED);
 	br_stp_port_timer_init(p);

net/bridge/br_netlink.c

···
 		       !!(p->flags & BR_FLOOD)) ||
 	    nla_put_u8(skb, IFLA_BRPORT_MCAST_FLOOD,
 		       !!(p->flags & BR_MCAST_FLOOD)) ||
+	    nla_put_u8(skb, IFLA_BRPORT_BCAST_FLOOD,
+		       !!(p->flags & BR_BCAST_FLOOD)) ||
 	    nla_put_u8(skb, IFLA_BRPORT_PROXYARP, !!(p->flags & BR_PROXYARP)) ||
 	    nla_put_u8(skb, IFLA_BRPORT_PROXYARP_WIFI,
 		       !!(p->flags & BR_PROXYARP_WIFI)) ||
···
 	br_set_port_flag(p, tb, IFLA_BRPORT_UNICAST_FLOOD, BR_FLOOD);
 	br_set_port_flag(p, tb, IFLA_BRPORT_MCAST_FLOOD, BR_MCAST_FLOOD);
 	br_set_port_flag(p, tb, IFLA_BRPORT_MCAST_TO_UCAST, BR_MULTICAST_TO_UNICAST);
+	br_set_port_flag(p, tb, IFLA_BRPORT_BCAST_FLOOD, BR_BCAST_FLOOD);
 	br_set_port_flag(p, tb, IFLA_BRPORT_PROXYARP, BR_PROXYARP);
 	br_set_port_flag(p, tb, IFLA_BRPORT_PROXYARP_WIFI, BR_PROXYARP_WIFI);
 

net/bridge/br_sysfs_if.c

···
 BRPORT_ATTR_FLAG(proxyarp, BR_PROXYARP);
 BRPORT_ATTR_FLAG(proxyarp_wifi, BR_PROXYARP_WIFI);
 BRPORT_ATTR_FLAG(multicast_flood, BR_MCAST_FLOOD);
+BRPORT_ATTR_FLAG(broadcast_flood, BR_BCAST_FLOOD);
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
···
 	&brport_attr_proxyarp,
 	&brport_attr_proxyarp_wifi,
 	&brport_attr_multicast_flood,
+	&brport_attr_broadcast_flood,
 	NULL
 };