bridge: Add a flag to control unicast packet flood.

Add a flag to control flood of unicast traffic.  By default, flood is
on and the bridge will flood unicast traffic if it doesn't know
the destination.  When the flag is turned off, unicast traffic
without an FDB will not be forwarded to the specified port.
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_link.h

@@ -222,6 +222,7 @@ enum {
 	IFLA_BRPORT_PROTECT,	/* root port protection    */
 	IFLA_BRPORT_FAST_LEAVE,	/* multicast fast leave    */
 	IFLA_BRPORT_LEARNING,	/* mac learning */
+	IFLA_BRPORT_UNICAST_FLOOD, /* flood unicast traffic */
 	__IFLA_BRPORT_MAX
 };
 #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)

net/bridge/br_device.c

@@ -58,10 +58,10 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 	skb_pull(skb, ETH_HLEN);
 
 	if (is_broadcast_ether_addr(dest))
-		br_flood_deliver(br, skb);
+		br_flood_deliver(br, skb, false);
 	else if (is_multicast_ether_addr(dest)) {
 		if (unlikely(netpoll_tx_running(dev))) {
-			br_flood_deliver(br, skb);
+			br_flood_deliver(br, skb, false);
 			goto out;
 		}
 		if (br_multicast_rcv(br, NULL, skb)) {
@@ -73,11 +73,11 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 		if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb))
 			br_multicast_deliver(mdst, skb);
 		else
-			br_flood_deliver(br, skb);
+			br_flood_deliver(br, skb, false);
 	} else if ((dst = __br_fdb_get(br, dest, vid)) != NULL)
 		br_deliver(dst->dst, skb);
 	else
-		br_flood_deliver(br, skb);
+		br_flood_deliver(br, skb, true);
 
 out:
 	rcu_read_unlock();

net/bridge/br_forward.c

@@ -174,7 +174,8 @@ static struct net_bridge_port *maybe_deliver(
 static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 		     struct sk_buff *skb0,
 		     void (*__packet_hook)(const struct net_bridge_port *p,
-					   struct sk_buff *skb))
+					   struct sk_buff *skb),
+		     bool unicast)
 {
 	struct net_bridge_port *p;
 	struct net_bridge_port *prev;
@@ -182,6 +183,9 @@ static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 	prev = NULL;
 
 	list_for_each_entry_rcu(p, &br->port_list, list) {
+		/* Do not flood unicast traffic to ports that turn it off */
+		if (unicast && !(p->flags & BR_FLOOD))
+			continue;
 		prev = maybe_deliver(prev, p, skb, __packet_hook);
 		if (IS_ERR(prev))
 			goto out;
@@ -203,16 +207,16 @@ static void br_flood(struct net_bridge *br, struct sk_buff *skb,
 
 
 /* called with rcu_read_lock */
-void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
+void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, bool unicast)
 {
-	br_flood(br, skb, NULL, __br_deliver);
+	br_flood(br, skb, NULL, __br_deliver, unicast);
 }
 
 /* called under bridge lock */
 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
-		      struct sk_buff *skb2)
+		      struct sk_buff *skb2, bool unicast)
 {
-	br_flood(br, skb, skb2, __br_forward);
+	br_flood(br, skb, skb2, __br_forward, unicast);
 }
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING

net/bridge/br_if.c

@@ -221,7 +221,7 @@ static struct net_bridge_port *new_nbp(struct net_bridge *br,
 	p->path_cost = port_cost(dev);
 	p->priority = 0x8000 >> BR_PORT_BITS;
 	p->port_no = index;
-	p->flags = BR_LEARNING;
+	p->flags = BR_LEARNING | BR_FLOOD;
 	br_init_port(p);
 	p->state = BR_STATE_DISABLED;
 	br_stp_port_timer_init(p);

net/bridge/br_input.c

@@ -65,6 +65,7 @@ int br_handle_frame_finish(struct sk_buff *skb)
 	struct net_bridge_fdb_entry *dst;
 	struct net_bridge_mdb_entry *mdst;
 	struct sk_buff *skb2;
+	bool unicast = true;
 	u16 vid = 0;
 
 	if (!p || p->state == BR_STATE_DISABLED)
@@ -95,9 +96,10 @@ int br_handle_frame_finish(struct sk_buff *skb)
 
 	dst = NULL;
 
-	if (is_broadcast_ether_addr(dest))
+	if (is_broadcast_ether_addr(dest)) {
 		skb2 = skb;
-	else if (is_multicast_ether_addr(dest)) {
+		unicast = false;
+	} else if (is_multicast_ether_addr(dest)) {
 		mdst = br_mdb_get(br, skb, vid);
 		if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {
 			if ((mdst && mdst->mglist) ||
@@ -110,6 +112,7 @@ int br_handle_frame_finish(struct sk_buff *skb)
 		} else
 			skb2 = skb;
 
+		unicast = false;
 		br->dev->stats.multicast++;
 	} else if ((dst = __br_fdb_get(br, dest, vid)) &&
 			dst->is_local) {
@@ -123,7 +126,7 @@ int br_handle_frame_finish(struct sk_buff *skb)
 			dst->used = jiffies;
 			br_forward(dst->dst, skb, skb2);
 		} else
-			br_flood_forward(br, skb, skb2);
+			br_flood_forward(br, skb, skb2, unicast);
 	}
 
 	if (skb2)

net/bridge/br_netlink.c

@@ -31,6 +31,7 @@ static inline size_t br_port_info_size(void)
 		+ nla_total_size(1)	/* IFLA_BRPORT_PROTECT */
 		+ nla_total_size(1)	/* IFLA_BRPORT_FAST_LEAVE */
 		+ nla_total_size(1)	/* IFLA_BRPORT_LEARNING */
+		+ nla_total_size(1)	/* IFLA_BRPORT_UNICAST_FLOOD */
 		+ 0;
 }
 
@@ -58,7 +59,8 @@ static int br_port_fill_attrs(struct sk_buff *skb,
 	    nla_put_u8(skb, IFLA_BRPORT_GUARD, !!(p->flags & BR_BPDU_GUARD)) ||
 	    nla_put_u8(skb, IFLA_BRPORT_PROTECT, !!(p->flags & BR_ROOT_BLOCK)) ||
 	    nla_put_u8(skb, IFLA_BRPORT_FAST_LEAVE, !!(p->flags & BR_MULTICAST_FAST_LEAVE)) ||
-	    nla_put_u8(skb, IFLA_BRPORT_LEARNING, !!(p->flags & BR_LEARNING)))
+	    nla_put_u8(skb, IFLA_BRPORT_LEARNING, !!(p->flags & BR_LEARNING)) ||
+	    nla_put_u8(skb, IFLA_BRPORT_UNICAST_FLOOD, !!(p->flags & BR_FLOOD)))
 		return -EMSGSIZE;
 
 	return 0;
@@ -284,6 +286,7 @@ static const struct nla_policy ifla_brport_policy[IFLA_BRPORT_MAX + 1] = {
 	[IFLA_BRPORT_GUARD]	= { .type = NLA_U8 },
 	[IFLA_BRPORT_PROTECT]	= { .type = NLA_U8 },
 	[IFLA_BRPORT_LEARNING]	= { .type = NLA_U8 },
+	[IFLA_BRPORT_UNICAST_FLOOD] = { .type = NLA_U8 },
 };
 
 /* Change the state of the port and notify spanning tree */
@@ -332,6 +335,7 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
 	br_set_port_flag(p, tb, IFLA_BRPORT_FAST_LEAVE, BR_MULTICAST_FAST_LEAVE);
 	br_set_port_flag(p, tb, IFLA_BRPORT_PROTECT, BR_ROOT_BLOCK);
 	br_set_port_flag(p, tb, IFLA_BRPORT_LEARNING, BR_LEARNING);
+	br_set_port_flag(p, tb, IFLA_BRPORT_UNICAST_FLOOD, BR_FLOOD);
 
 	if (tb[IFLA_BRPORT_COST]) {
 		err = br_stp_set_path_cost(p, nla_get_u32(tb[IFLA_BRPORT_COST]));

net/bridge/br_private.h

@@ -159,6 +159,7 @@ struct net_bridge_port
 #define BR_MULTICAST_FAST_LEAVE	0x00000008
 #define BR_ADMIN_COST		0x00000010
 #define BR_LEARNING		0x00000020
+#define BR_FLOOD		0x00000040
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	u32				multicast_startup_queries_sent;
@@ -414,9 +415,10 @@ extern int br_dev_queue_push_xmit(struct sk_buff *skb);
 extern void br_forward(const struct net_bridge_port *to,
 		struct sk_buff *skb, struct sk_buff *skb0);
 extern int br_forward_finish(struct sk_buff *skb);
-extern void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb);
+extern void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb,
+			     bool unicast);
 extern void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
-			     struct sk_buff *skb2);
+			     struct sk_buff *skb2, bool unicast);
 
 /* br_if.c */
 extern void br_port_carrier_check(struct net_bridge_port *p);

net/bridge/br_sysfs_if.c

@@ -159,6 +159,7 @@ BRPORT_ATTR_FLAG(hairpin_mode, BR_HAIRPIN_MODE);
 BRPORT_ATTR_FLAG(bpdu_guard, BR_BPDU_GUARD);
 BRPORT_ATTR_FLAG(root_block, BR_ROOT_BLOCK);
 BRPORT_ATTR_FLAG(learning, BR_LEARNING);
+BRPORT_ATTR_FLAG(unicast_flood, BR_FLOOD);
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
@@ -197,6 +198,7 @@ static const struct brport_attribute *brport_attrs[] = {
 	&brport_attr_bpdu_guard,
 	&brport_attr_root_block,
 	&brport_attr_learning,
+	&brport_attr_unicast_flood,
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	&brport_attr_multicast_router,
 	&brport_attr_multicast_fast_leave,