bridge: Add core IGMP snooping support

This patch adds the core functionality of IGMP snooping support
without actually hooking it up.  So this patch should be a no-op
as far as the bridge's external behaviour is concerned.

All the new code and data is controlled by the Kconfig option
BRIDGE_IGMP_SNOOPING.  A run-time toggle is also available.

The multicast switching is done using an hash table that is
lockless on the read-side through RCU.  On the write-side the
new multicast_lock is used for all operations.  The hash table
supports dynamic growth/rehashing.

The hash table will be rehashed if any chain length exceeds a
preset limit.  If rehashing does not reduce the maximum chain
length then snooping will be disabled.

These features may be added in future (in no particular order):

* IGMPv3 source support
* Non-querier router detection
* IPv6

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 139 insertions, 0 deletions

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index fad5a2669d34..44345c9afdd3 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -57,6 +57,41 @@ struct net_bridge_fdb_entry
         unsigned char                   is_static;
 };
 
+struct net_bridge_port_group {
+        struct net_bridge_port          *port;
+        struct net_bridge_port_group    *next;
+        struct hlist_node               mglist;
+        struct rcu_head                 rcu;
+        struct timer_list               timer;
+        struct timer_list               query_timer;
+        __be32                          addr;
+        u32                             queries_sent;
+};
+
+struct net_bridge_mdb_entry
+{
+        struct hlist_node               hlist[2];
+        struct hlist_node               mglist;
+        struct net_bridge               *br;
+        struct net_bridge_port_group    *ports;
+        struct rcu_head                 rcu;
+        struct timer_list               timer;
+        struct timer_list               query_timer;
+        __be32                          addr;
+        u32                             queries_sent;
+};
+
+struct net_bridge_mdb_htable
+{
+        struct hlist_head               *mhash;
+        struct rcu_head                 rcu;
+        struct net_bridge_mdb_htable    *old;
+        u32                             size;
+        u32                             max;
+        u32                             secret;
+        u32                             ver;
+};
+
 struct net_bridge_port
 {
         struct net_bridge               *br;
@@ -84,6 +119,15 @@ struct net_bridge_port
 
         unsigned long                   flags;
 #define BR_HAIRPIN_MODE         0x00000001
+
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+        u32                             multicast_startup_queries_sent;
+        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
 };
 
 struct net_bridge
@@ -124,6 +168,35 @@ struct net_bridge
         unsigned char                   topology_change;
         unsigned char                   topology_change_detected;
 
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+        unsigned char                   multicast_router;
+
+        u8                              multicast_disabled:1;
+
+        u32                             hash_elasticity;
+        u32                             hash_max;
+
+        u32                             multicast_last_member_count;
+        u32                             multicast_startup_queries_sent;
+        u32                             multicast_startup_query_count;
+
+        unsigned long                   multicast_last_member_interval;
+        unsigned long                   multicast_membership_interval;
+        unsigned long                   multicast_querier_interval;
+        unsigned long                   multicast_query_interval;
+        unsigned long                   multicast_query_response_interval;
+        unsigned long                   multicast_startup_query_interval;
+
+        spinlock_t                      multicast_lock;
+        struct net_bridge_mdb_htable    *mdb;
+        struct hlist_head               router_list;
+        struct hlist_head               mglist;
+
+        struct timer_list               multicast_router_timer;
+        struct timer_list               multicast_querier_timer;
+        struct timer_list               multicast_query_timer;
+#endif
+
         struct timer_list               hello_timer;
         struct timer_list               tcn_timer;
         struct timer_list               topology_change_timer;
@@ -133,6 +206,8 @@ struct net_bridge
 
 struct br_input_skb_cb {
         struct net_device *brdev;
+        int igmp;
+        int mrouters_only;
 };
 
 #define BR_INPUT_SKB_CB(__skb)  ((struct br_input_skb_cb *)(__skb)->cb)
@@ -204,6 +279,70 @@ extern struct sk_buff *br_handle_frame(struct net_bridge_port *p,
 extern int br_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
 extern int br_ioctl_deviceless_stub(struct net *net, unsigned int cmd, void __user *arg);
 
+/* br_multicast.c */
+#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
+extern int br_multicast_rcv(struct net_bridge *br,
+                            struct net_bridge_port *port,
+                            struct sk_buff *skb);
+extern struct net_bridge_mdb_entry *br_mdb_get(struct net_bridge *br,
+                                               struct sk_buff *skb);
+extern void br_multicast_add_port(struct net_bridge_port *port);
+extern void br_multicast_del_port(struct net_bridge_port *port);
+extern void br_multicast_enable_port(struct net_bridge_port *port);
+extern void br_multicast_disable_port(struct net_bridge_port *port);
+extern void br_multicast_init(struct net_bridge *br);
+extern void br_multicast_open(struct net_bridge *br);
+extern void br_multicast_stop(struct net_bridge *br);
+#else
+static inline int br_multicast_rcv(struct net_bridge *br,
+                                   struct net_bridge_port *port,
+                                   struct sk_buff *skb)
+{
+        return 0;
+}
+
+static inline struct net_bridge_mdb_entry *br_mdb_get(struct net_bridge *br,
+                                                      struct sk_buff *skb)
+{
+        return NULL;
+}
+
+static inline void br_multicast_add_port(struct net_bridge_port *port)
+{
+}
+
+static inline void br_multicast_del_port(struct net_bridge_port *port)
+{
+}
+
+static inline void br_multicast_enable_port(struct net_bridge_port *port)
+{
+}
+
+static inline void br_multicast_disable_port(struct net_bridge_port *port)
+{
+}
+
+static inline void br_multicast_init(struct net_bridge *br)
+{
+}
+
+static inline void br_multicast_open(struct net_bridge *br)
+{
+}
+
+static inline void br_multicast_stop(struct net_bridge *br)
+{
+}
+#endif
+
+static inline bool br_multicast_is_router(struct net_bridge *br)
+{
+        return br->multicast_router == 2 ||
+               (br->multicast_router == 1 &&
+                timer_pending(&br->multicast_router_timer));
+}
+
 /* br_netfilter.c */
 #ifdef CONFIG_BRIDGE_NETFILTER
 extern int br_netfilter_init(void);