bridge: separate querier and query timer into IGMP/IPv4 and MLD/IPv6 ones

Currently we would still potentially suffer multicast packet loss if there
is just either an IGMP or an MLD querier: For the former case, we would
possibly drop IPv6 multicast packets, for the latter IPv4 ones. This is
because we are currently assuming that if either an IGMP or MLD querier
is present that the other one is present, too.

This patch makes the behaviour and fix added in
"bridge: disable snooping if there is no querier" (b00589af)
to also work if there is either just an IGMP or an MLD querier on the
link: It refines the deactivation of the snooping to be protocol
specific by using separate timers for the snooped IGMP and MLD queries
as well as separate timers for our internal IGMP and MLD queriers.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_device.c

@@ -71,7 +71,7 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 
 		mdst = br_mdb_get(br, skb, vid);
 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
-		    br_multicast_querier_exists(br))
+		    br_multicast_querier_exists(br, eth_hdr(skb)))
 			br_multicast_deliver(mdst, skb);
 		else
 			br_flood_deliver(br, skb, false);

net/bridge/br_input.c

@@ -102,7 +102,7 @@ int br_handle_frame_finish(struct sk_buff *skb)
 	} else if (is_multicast_ether_addr(dest)) {
 		mdst = br_mdb_get(br, skb, vid);
 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
-		    br_multicast_querier_exists(br)) {
+		    br_multicast_querier_exists(br, eth_hdr(skb))) {
 			if ((mdst && mdst->mglist) ||
 			    br_multicast_is_router(br))
 				skb2 = skb;

net/bridge/br_mdb.c

@@ -414,16 +414,20 @@ static int __br_mdb_del(struct net_bridge *br, struct br_mdb_entry *entry)
 	if (!netif_running(br->dev) || br->multicast_disabled)
 		return -EINVAL;
 
-	if (timer_pending(&br->multicast_querier_timer))
+	ip.proto = entry->addr.proto;
+	if (ip.proto == htons(ETH_P_IP)) {
+		if (timer_pending(&br->ip4_querier.timer))
 			return -EBUSY;
 
-	ip.proto = entry->addr.proto;
-	if (ip.proto == htons(ETH_P_IP))
 		ip.u.ip4 = entry->addr.u.ip4;
 #if IS_ENABLED(CONFIG_IPV6)
-	else
+	} else {
+		if (timer_pending(&br->ip6_querier.timer))
+			return -EBUSY;
+
 		ip.u.ip6 = entry->addr.u.ip6;
 #endif
+	}
 
 	spin_lock_bh(&br->multicast_lock);
 	mdb = mlock_dereference(br->mdb, br);

net/bridge/br_private.h

@@ -66,6 +66,20 @@ struct br_ip
 	__u16		vid;
 };
 
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+/* our own querier */
+struct bridge_mcast_query {
+	struct timer_list	timer;
+	u32			startup_sent;
+};
+
+/* other querier */
+struct bridge_mcast_querier {
+	struct timer_list		timer;
+	unsigned long			delay_time;
+};
+#endif
+
 struct net_port_vlans {
 	u16				port_idx;
 	u16				pvid;
@@ -162,10 +176,12 @@ struct net_bridge_port
 #define BR_FLOOD		0x00000040
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
-	u32				multicast_startup_queries_sent;
+	struct bridge_mcast_query	ip4_query;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct bridge_mcast_query	ip6_query;
+#endif /* IS_ENABLED(CONFIG_IPV6) */
 	unsigned char			multicast_router;
 	struct timer_list		multicast_router_timer;
-	struct timer_list		multicast_query_timer;
 	struct hlist_head		mglist;
 	struct hlist_node		rlist;
 #endif
@@ -258,7 +274,6 @@ struct net_bridge
 	u32				hash_max;
 
 	u32				multicast_last_member_count;
-	u32				multicast_startup_queries_sent;
 	u32				multicast_startup_query_count;
 
 	unsigned long			multicast_last_member_interval;
@@ -267,15 +282,18 @@ struct net_bridge
 	unsigned long			multicast_query_interval;
 	unsigned long			multicast_query_response_interval;
 	unsigned long			multicast_startup_query_interval;
-	unsigned long			multicast_querier_delay_time;
 
 	spinlock_t			multicast_lock;
 	struct net_bridge_mdb_htable __rcu *mdb;
 	struct hlist_head		router_list;
 
 	struct timer_list		multicast_router_timer;
-	struct timer_list		multicast_querier_timer;
-	struct timer_list		multicast_query_timer;
+	struct bridge_mcast_querier	ip4_querier;
+	struct bridge_mcast_query	ip4_query;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct bridge_mcast_querier	ip6_querier;
+	struct bridge_mcast_query	ip6_query;
+#endif /* IS_ENABLED(CONFIG_IPV6) */
 #endif
 
 	struct timer_list		hello_timer;
@@ -503,11 +521,27 @@ static inline bool br_multicast_is_router(struct net_bridge *br)
 		timer_pending(&br->multicast_router_timer));
 }
 
-static inline bool br_multicast_querier_exists(struct net_bridge *br)
+static inline bool
+__br_multicast_querier_exists(struct net_bridge *br,
+			      struct bridge_mcast_querier *querier)
+{
+	return time_is_before_jiffies(querier->delay_time) &&
+	       (br->multicast_querier || timer_pending(&querier->timer));
+}
+
+static inline bool br_multicast_querier_exists(struct net_bridge *br,
+					       struct ethhdr *eth)
 {
-	return time_is_before_jiffies(br->multicast_querier_delay_time) &&
-	       (br->multicast_querier ||
-		timer_pending(&br->multicast_querier_timer));
+	switch (eth->h_proto) {
+	case (htons(ETH_P_IP)):
+		return __br_multicast_querier_exists(br, &br->ip4_querier);
+#if IS_ENABLED(CONFIG_IPV6)
+	case (htons(ETH_P_IPV6)):
+		return __br_multicast_querier_exists(br, &br->ip6_querier);
+#endif
+	default:
+		return false;
+	}
 }
 #else
 static inline int br_multicast_rcv(struct net_bridge *br,
@@ -565,7 +599,8 @@ static inline bool br_multicast_is_router(struct net_bridge *br)
 {
 	return 0;
 }
-static inline bool br_multicast_querier_exists(struct net_bridge *br)
+static inline bool br_multicast_querier_exists(struct net_bridge *br,
+					       struct ethhdr *eth)
 {
 	return false;
 }