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>

4 files changed, 1288 insertions, 0 deletions

diff --git a/net/bridge/Kconfig b/net/bridge/Kconfig
index e143ca67888..78dd5497210 100644
--- a/net/bridge/Kconfig
+++ b/net/bridge/Kconfig
@@ -31,3 +31,15 @@ config BRIDGE
 	  will be called bridge.
 
 	  If unsure, say N.
+
+config BRIDGE_IGMP_SNOOPING
+	bool "IGMP snooping"
+	default y
+	---help---
+	  If you say Y here, then the Ethernet bridge will be able selectively
+	  forward multicast traffic based on IGMP traffic received from each
+	  port.
+
+	  Say N to exclude this support and reduce the binary size.
+
+	  If unsure, say Y.
diff --git a/net/bridge/Makefile b/net/bridge/Makefile
index f444c12cde5..d0359ea8ee7 100644
--- a/net/bridge/Makefile
+++ b/net/bridge/Makefile
@@ -12,4 +12,6 @@ bridge-$(CONFIG_SYSFS) += br_sysfs_if.o br_sysfs_br.o
 
 bridge-$(CONFIG_BRIDGE_NETFILTER) += br_netfilter.o
 
+bridge-$(CONFIG_BRIDGE_IGMP_SNOOPING) += br_multicast.o
+
 obj-$(CONFIG_BRIDGE_NF_EBTABLES) += netfilter/
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
new file mode 100644
index 00000000000..746b5a611aa
--- /dev/null
+++ b/net/bridge/br_multicast.c
@@ -0,0 +1,1135 @@
+/*
+ * Bridge multicast support.
+ *
+ * Copyright (c) 2010 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/if_ether.h>
+#include <linux/igmp.h>
+#include <linux/jhash.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/netfilter_bridge.h>
+#include <linux/random.h>
+#include <linux/rculist.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <net/ip.h>
+
+#include "br_private.h"
+
+static inline int br_ip_hash(struct net_bridge_mdb_htable *mdb, __be32 ip)
+{
+	return jhash_1word(mdb->secret, (u32)ip) & (mdb->max - 1);
+}
+
+static struct net_bridge_mdb_entry *__br_mdb_ip_get(
+	struct net_bridge_mdb_htable *mdb, __be32 dst, int hash)
+{
+	struct net_bridge_mdb_entry *mp;
+	struct hlist_node *p;
+
+	hlist_for_each_entry(mp, p, &mdb->mhash[hash], hlist[mdb->ver]) {
+		if (dst == mp->addr)
+			return mp;
+	}
+
+	return NULL;
+}
+
+static struct net_bridge_mdb_entry *br_mdb_ip_get(
+	struct net_bridge_mdb_htable *mdb, __be32 dst)
+{
+	return __br_mdb_ip_get(mdb, dst, br_ip_hash(mdb, dst));
+}
+
+struct net_bridge_mdb_entry *br_mdb_get(struct net_bridge *br,
+					struct sk_buff *skb)
+{
+	struct net_bridge_mdb_htable *mdb = br->mdb;
+
+	if (!mdb || br->multicast_disabled)
+		return NULL;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		if (BR_INPUT_SKB_CB(skb)->igmp)
+			break;
+		return br_mdb_ip_get(mdb, ip_hdr(skb)->daddr);
+	}
+
+	return NULL;
+}
+
+static void br_mdb_free(struct rcu_head *head)
+{
+	struct net_bridge_mdb_htable *mdb =
+		container_of(head, struct net_bridge_mdb_htable, rcu);
+	struct net_bridge_mdb_htable *old = mdb->old;
+
+	mdb->old = NULL;
+	kfree(old->mhash);
+	kfree(old);
+}
+
+static int br_mdb_copy(struct net_bridge_mdb_htable *new,
+		       struct net_bridge_mdb_htable *old,
+		       int elasticity)
+{
+	struct net_bridge_mdb_entry *mp;
+	struct hlist_node *p;
+	int maxlen;
+	int len;
+	int i;
+
+	for (i = 0; i < old->max; i++)
+		hlist_for_each_entry(mp, p, &old->mhash[i], hlist[old->ver])
+			hlist_add_head(&mp->hlist[new->ver],
+				       &new->mhash[br_ip_hash(new, mp->addr)]);
+
+	if (!elasticity)
+		return 0;
+
+	maxlen = 0;
+	for (i = 0; i < new->max; i++) {
+		len = 0;
+		hlist_for_each_entry(mp, p, &new->mhash[i], hlist[new->ver])
+			len++;
+		if (len > maxlen)
+			maxlen = len;
+	}
+
+	return maxlen > elasticity ? -EINVAL : 0;
+}
+
+static void br_multicast_free_pg(struct rcu_head *head)
+{
+	struct net_bridge_port_group *p =
+		container_of(head, struct net_bridge_port_group, rcu);
+
+	kfree(p);
+}
+
+static void br_multicast_free_group(struct rcu_head *head)
+{
+	struct net_bridge_mdb_entry *mp =
+		container_of(head, struct net_bridge_mdb_entry, rcu);
+
+	kfree(mp);
+}
+
+static void br_multicast_group_expired(unsigned long data)
+{
+	struct net_bridge_mdb_entry *mp = (void *)data;
+	struct net_bridge *br = mp->br;
+	struct net_bridge_mdb_htable *mdb;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev) || timer_pending(&mp->timer))
+		goto out;
+
+	if (!hlist_unhashed(&mp->mglist))
+		hlist_del_init(&mp->mglist);
+
+	if (mp->ports)
+		goto out;
+
+	mdb = br->mdb;
+	hlist_del_rcu(&mp->hlist[mdb->ver]);
+	mdb->size--;
+
+	del_timer(&mp->query_timer);
+	call_rcu_bh(&mp->rcu, br_multicast_free_group);
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+static void br_multicast_del_pg(struct net_bridge *br,
+				struct net_bridge_port_group *pg)
+{
+	struct net_bridge_mdb_htable *mdb = br->mdb;
+	struct net_bridge_mdb_entry *mp;
+	struct net_bridge_port_group *p;
+	struct net_bridge_port_group **pp;
+
+	mp = br_mdb_ip_get(mdb, pg->addr);
+	if (WARN_ON(!mp))
+		return;
+
+	for (pp = &mp->ports; (p = *pp); pp = &p->next) {
+		if (p != pg)
+			continue;
+
+		*pp = p->next;
+		hlist_del_init(&p->mglist);
+		del_timer(&p->timer);
+		del_timer(&p->query_timer);
+		call_rcu_bh(&p->rcu, br_multicast_free_pg);
+
+		if (!mp->ports && hlist_unhashed(&mp->mglist) &&
+		    netif_running(br->dev))
+			mod_timer(&mp->timer, jiffies);
+
+		return;
+	}
+
+	WARN_ON(1);
+}
+
+static void br_multicast_port_group_expired(unsigned long data)
+{
+	struct net_bridge_port_group *pg = (void *)data;
+	struct net_bridge *br = pg->port->br;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev) || timer_pending(&pg->timer) ||
+	    hlist_unhashed(&pg->mglist))
+		goto out;
+
+	br_multicast_del_pg(br, pg);
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+static int br_mdb_rehash(struct net_bridge_mdb_htable **mdbp, int max,
+			 int elasticity)
+{
+	struct net_bridge_mdb_htable *old = *mdbp;
+	struct net_bridge_mdb_htable *mdb;
+	int err;
+
+	mdb = kmalloc(sizeof(*mdb), GFP_ATOMIC);
+	if (!mdb)
+		return -ENOMEM;
+
+	mdb->max = max;
+	mdb->old = old;
+
+	mdb->mhash = kzalloc(max * sizeof(*mdb->mhash), GFP_ATOMIC);
+	if (!mdb->mhash) {
+		kfree(mdb);
+		return -ENOMEM;
+	}
+
+	mdb->size = old ? old->size : 0;
+	mdb->ver = old ? old->ver ^ 1 : 0;
+
+	if (!old || elasticity)
+		get_random_bytes(&mdb->secret, sizeof(mdb->secret));
+	else
+		mdb->secret = old->secret;
+
+	if (!old)
+		goto out;
+
+	err = br_mdb_copy(mdb, old, elasticity);
+	if (err) {
+		kfree(mdb->mhash);
+		kfree(mdb);
+		return err;
+	}
+
+	call_rcu_bh(&mdb->rcu, br_mdb_free);
+
+out:
+	rcu_assign_pointer(*mdbp, mdb);
+
+	return 0;
+}
+
+static struct sk_buff *br_multicast_alloc_query(struct net_bridge *br,
+						__be32 group)
+{
+	struct sk_buff *skb;
+	struct igmphdr *ih;
+	struct ethhdr *eth;
+	struct iphdr *iph;
+
+	skb = netdev_alloc_skb_ip_align(br->dev, sizeof(*eth) + sizeof(*iph) +
+						 sizeof(*ih) + 4);
+	if (!skb)
+		goto out;
+
+	skb->protocol = htons(ETH_P_IP);
+
+	skb_reset_mac_header(skb);
+	eth = eth_hdr(skb);
+
+	memcpy(eth->h_source, br->dev->dev_addr, 6);
+	eth->h_dest[0] = 1;
+	eth->h_dest[1] = 0;
+	eth->h_dest[2] = 0x5e;
+	eth->h_dest[3] = 0;
+	eth->h_dest[4] = 0;
+	eth->h_dest[5] = 1;
+	eth->h_proto = htons(ETH_P_IP);
+	skb_put(skb, sizeof(*eth));
+
+	skb_set_network_header(skb, skb->len);
+	iph = ip_hdr(skb);
+
+	iph->version = 4;
+	iph->ihl = 6;
+	iph->tos = 0xc0;
+	iph->tot_len = htons(sizeof(*iph) + sizeof(*ih) + 4);
+	iph->id = 0;
+	iph->frag_off = htons(IP_DF);
+	iph->ttl = 1;
+	iph->protocol = IPPROTO_IGMP;
+	iph->saddr = 0;
+	iph->daddr = htonl(INADDR_ALLHOSTS_GROUP);
+	((u8 *)&iph[1])[0] = IPOPT_RA;
+	((u8 *)&iph[1])[1] = 4;
+	((u8 *)&iph[1])[2] = 0;
+	((u8 *)&iph[1])[3] = 0;
+	ip_send_check(iph);
+	skb_put(skb, 24);
+
+	skb_set_transport_header(skb, skb->len);
+	ih = igmp_hdr(skb);
+	ih->type = IGMP_HOST_MEMBERSHIP_QUERY;
+	ih->code = (group ? br->multicast_last_member_interval :
+			    br->multicast_query_response_interval) /
+		   (HZ / IGMP_TIMER_SCALE);
+	ih->group = group;
+	ih->csum = 0;
+	ih->csum = ip_compute_csum((void *)ih, sizeof(struct igmphdr));
+	skb_put(skb, sizeof(*ih));
+
+	__skb_pull(skb, sizeof(*eth));
+
+out:
+	return skb;
+}
+
+static void br_multicast_send_group_query(struct net_bridge_mdb_entry *mp)
+{
+	struct net_bridge *br = mp->br;
+	struct sk_buff *skb;
+
+	skb = br_multicast_alloc_query(br, mp->addr);
+	if (!skb)
+		goto timer;
+
+	netif_rx(skb);
+
+timer:
+	if (++mp->queries_sent < br->multicast_last_member_count)
+		mod_timer(&mp->query_timer,
+			  jiffies + br->multicast_last_member_interval);
+}
+
+static void br_multicast_group_query_expired(unsigned long data)
+{
+	struct net_bridge_mdb_entry *mp = (void *)data;
+	struct net_bridge *br = mp->br;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev) || hlist_unhashed(&mp->mglist) ||
+	    mp->queries_sent >= br->multicast_last_member_count)
+		goto out;
+
+	br_multicast_send_group_query(mp);
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+static void br_multicast_send_port_group_query(struct net_bridge_port_group *pg)
+{
+	struct net_bridge_port *port = pg->port;
+	struct net_bridge *br = port->br;
+	struct sk_buff *skb;
+
+	skb = br_multicast_alloc_query(br, pg->addr);
+	if (!skb)
+		goto timer;
+
+	br_deliver(port, skb);
+
+timer:
+	if (++pg->queries_sent < br->multicast_last_member_count)
+		mod_timer(&pg->query_timer,
+			  jiffies + br->multicast_last_member_interval);
+}
+
+static void br_multicast_port_group_query_expired(unsigned long data)
+{
+	struct net_bridge_port_group *pg = (void *)data;
+	struct net_bridge_port *port = pg->port;
+	struct net_bridge *br = port->br;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev) || hlist_unhashed(&pg->mglist) ||
+	    pg->queries_sent >= br->multicast_last_member_count)
+		goto out;
+
+	br_multicast_send_port_group_query(pg);
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+static struct net_bridge_mdb_entry *br_multicast_get_group(
+	struct net_bridge *br, struct net_bridge_port *port, __be32 group,
+	int hash)
+{
+	struct net_bridge_mdb_htable *mdb = br->mdb;
+	struct net_bridge_mdb_entry *mp;
+	struct hlist_node *p;
+	unsigned count = 0;
+	unsigned max;
+	int elasticity;
+	int err;
+
+	hlist_for_each_entry(mp, p, &mdb->mhash[hash], hlist[mdb->ver]) {
+		count++;
+		if (unlikely(group == mp->addr)) {
+			return mp;
+		}
+	}
+
+	elasticity = 0;
+	max = mdb->max;
+
+	if (unlikely(count > br->hash_elasticity && count)) {
+		if (net_ratelimit())
+			printk(KERN_INFO "%s: Multicast hash table "
+			       "chain limit reached: %s\n",
+			       br->dev->name, port ? port->dev->name :
+						     br->dev->name);
+
+		elasticity = br->hash_elasticity;
+	}
+
+	if (mdb->size >= max) {
+		max *= 2;
+		if (unlikely(max >= br->hash_max)) {
+			printk(KERN_WARNING "%s: Multicast hash table maximum "
+			       "reached, disabling snooping: %s, %d\n",
+			       br->dev->name, port ? port->dev->name :
+						     br->dev->name,
+			       max);
+			err = -E2BIG;
+disable:
+			br->multicast_disabled = 1;
+			goto err;
+		}
+	}
+
+	if (max > mdb->max || elasticity) {
+		if (mdb->old) {
+			if (net_ratelimit())
+				printk(KERN_INFO "%s: Multicast hash table "
+				       "on fire: %s\n",
+				       br->dev->name, port ? port->dev->name :
+							     br->dev->name);
+			err = -EEXIST;
+			goto err;
+		}
+
+		err = br_mdb_rehash(&br->mdb, max, elasticity);
+		if (err) {
+			printk(KERN_WARNING "%s: Cannot rehash multicast "
+			       "hash table, disabling snooping: "
+			       "%s, %d, %d\n",
+			       br->dev->name, port ? port->dev->name :
+						     br->dev->name,
+			       mdb->size, err);
+			goto disable;
+		}
+
+		err = -EAGAIN;
+		goto err;
+	}
+
+	return NULL;
+
+err:
+	mp = ERR_PTR(err);
+	return mp;
+}
+
+static struct net_bridge_mdb_entry *br_multicast_new_group(
+	struct net_bridge *br, struct net_bridge_port *port, __be32 group)
+{
+	struct net_bridge_mdb_htable *mdb = br->mdb;
+	struct net_bridge_mdb_entry *mp;
+	int hash;
+
+	if (!mdb) {
+		if (br_mdb_rehash(&br->mdb, BR_HASH_SIZE, 0))
+			return NULL;
+		goto rehash;
+	}
+
+	hash = br_ip_hash(mdb, group);
+	mp = br_multicast_get_group(br, port, group, hash);
+	switch (PTR_ERR(mp)) {
+	case 0:
+		break;
+
+	case -EAGAIN:
+rehash:
+		mdb = br->mdb;
+		hash = br_ip_hash(mdb, group);
+		break;
+
+	default:
+		goto out;
+	}
+
+	mp = kzalloc(sizeof(*mp), GFP_ATOMIC);
+	if (unlikely(!mp))
+		goto out;
+
+	mp->br = br;
+	mp->addr = group;
+	setup_timer(&mp->timer, br_multicast_group_expired,
+		    (unsigned long)mp);
+	setup_timer(&mp->query_timer, br_multicast_group_query_expired,
+		    (unsigned long)mp);
+
+	hlist_add_head_rcu(&mp->hlist[mdb->ver], &mdb->mhash[hash]);
+	mdb->size++;
+
+out:
+	return mp;
+}
+
+static int br_multicast_add_group(struct net_bridge *br,
+				  struct net_bridge_port *port, __be32 group)
+{
+	struct net_bridge_mdb_entry *mp;
+	struct net_bridge_port_group *p;
+	struct net_bridge_port_group **pp;
+	unsigned long now = jiffies;
+	int err;
+
+	if (ipv4_is_local_multicast(group))
+		return 0;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev) ||
+	    (port && port->state == BR_STATE_DISABLED))
+		goto out;
+
+	mp = br_multicast_new_group(br, port, group);
+	err = PTR_ERR(mp);
+	if (unlikely(IS_ERR(mp) || !mp))
+		goto err;
+
+	if (!port) {
+		hlist_add_head(&mp->mglist, &br->mglist);
+		mod_timer(&mp->timer, now + br->multicast_membership_interval);
+		goto out;
+	}
+
+	for (pp = &mp->ports; (p = *pp); pp = &p->next) {
+		if (p->port == port)
+			goto found;
+		if ((unsigned long)p->port < (unsigned long)port)
+			break;
+	}
+
+	p = kzalloc(sizeof(*p), GFP_ATOMIC);
+	err = -ENOMEM;
+	if (unlikely(!p))
+		goto err;
+
+	p->addr = group;
+	p->port = port;
+	p->next = *pp;
+	hlist_add_head(&p->mglist, &port->mglist);
+	setup_timer(&p->timer, br_multicast_port_group_expired,
+		    (unsigned long)p);
+	setup_timer(&p->query_timer, br_multicast_port_group_query_expired,
+		    (unsigned long)p);
+
+	rcu_assign_pointer(*pp, p);
+
+found:
+	mod_timer(&p->timer, now + br->multicast_membership_interval);
+out:
+	err = 0;
+
+err:
+	spin_unlock(&br->multicast_lock);
+	return err;
+}
+
+static void br_multicast_router_expired(unsigned long data)
+{
+	struct net_bridge_port *port = (void *)data;
+	struct net_bridge *br = port->br;
+
+	spin_lock(&br->multicast_lock);
+	if (port->multicast_router != 1 ||
+	    timer_pending(&port->multicast_router_timer) ||
+	    hlist_unhashed(&port->rlist))
+		goto out;
+
+	hlist_del_init_rcu(&port->rlist);
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+static void br_multicast_local_router_expired(unsigned long data)
+{
+}
+
+static void br_multicast_send_query(struct net_bridge *br,
+				    struct net_bridge_port *port, u32 sent)
+{
+	unsigned long time;
+	struct sk_buff *skb;
+
+	if (!netif_running(br->dev) || br->multicast_disabled ||
+	    timer_pending(&br->multicast_querier_timer))
+		return;
+
+	skb = br_multicast_alloc_query(br, 0);
+	if (!skb)
+		goto timer;
+
+	if (port) {
+		__skb_push(skb, sizeof(struct ethhdr));
+		skb->dev = port->dev;
+		NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
+			dev_queue_xmit);
+	} else
+		netif_rx(skb);
+
+timer:
+	time = jiffies;
+	time += sent < br->multicast_startup_query_count ?
+		br->multicast_startup_query_interval :
+		br->multicast_query_interval;
+	mod_timer(port ? &port->multicast_query_timer :
+			 &br->multicast_query_timer, time);
+}
+
+static void br_multicast_port_query_expired(unsigned long data)
+{
+	struct net_bridge_port *port = (void *)data;
+	struct net_bridge *br = port->br;
+
+	spin_lock(&br->multicast_lock);
+	if (port && (port->state == BR_STATE_DISABLED ||
+		     port->state == BR_STATE_BLOCKING))
+		goto out;
+
+	if (port->multicast_startup_queries_sent <
+	    br->multicast_startup_query_count)
+		port->multicast_startup_queries_sent++;
+
+	br_multicast_send_query(port->br, port,
+				port->multicast_startup_queries_sent);
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+void br_multicast_add_port(struct net_bridge_port *port)
+{
+	port->multicast_router = 1;
+
+	setup_timer(&port->multicast_router_timer, br_multicast_router_expired,
+		    (unsigned long)port);
+	setup_timer(&port->multicast_query_timer,
+		    br_multicast_port_query_expired, (unsigned long)port);
+}
+
+void br_multicast_del_port(struct net_bridge_port *port)
+{
+	del_timer_sync(&port->multicast_router_timer);
+}
+
+void br_multicast_enable_port(struct net_bridge_port *port)
+{
+	struct net_bridge *br = port->br;
+
+	spin_lock(&br->multicast_lock);
+	if (br->multicast_disabled || !netif_running(br->dev))
+		goto out;
+
+	port->multicast_startup_queries_sent = 0;
+
+	if (try_to_del_timer_sync(&port->multicast_query_timer) >= 0 ||
+	    del_timer(&port->multicast_query_timer))
+		mod_timer(&port->multicast_query_timer, jiffies);
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+void br_multicast_disable_port(struct net_bridge_port *port)
+{
+	struct net_bridge *br = port->br;
+	struct net_bridge_port_group *pg;
+	struct hlist_node *p, *n;
+
+	spin_lock(&br->multicast_lock);
+	hlist_for_each_entry_safe(pg, p, n, &port->mglist, mglist)
+		br_multicast_del_pg(br, pg);
+
+	if (!hlist_unhashed(&port->rlist))
+		hlist_del_init_rcu(&port->rlist);
+	del_timer(&port->multicast_router_timer);
+	del_timer(&port->multicast_query_timer);
+	spin_unlock(&br->multicast_lock);
+}
+
+static int br_multicast_igmp3_report(struct net_bridge *br,
+				     struct net_bridge_port *port,
+				     struct sk_buff *skb)
+{
+	struct igmpv3_report *ih;
+	struct igmpv3_grec *grec;
+	int i;
+	int len;
+	int num;
+	int type;
+	int err = 0;
+	__be32 group;
+
+	if (!pskb_may_pull(skb, sizeof(*ih)))
+		return -EINVAL;
+
+	ih = igmpv3_report_hdr(skb);
+	num = ntohs(ih->ngrec);
+	len = sizeof(*ih);
+
+	for (i = 0; i < num; i++) {
+		len += sizeof(*grec);
+		if (!pskb_may_pull(skb, len))
+			return -EINVAL;
+
+		grec = (void *)(skb->data + len);
+		group = grec->grec_mca;
+		type = grec->grec_type;
+
+		len += grec->grec_nsrcs * 4;
+		if (!pskb_may_pull(skb, len))
+			return -EINVAL;
+
+		/* We treat this as an IGMPv2 report for now. */
+		switch (type) {
+		case IGMPV3_MODE_IS_INCLUDE:
+		case IGMPV3_MODE_IS_EXCLUDE:
+		case IGMPV3_CHANGE_TO_INCLUDE:
+		case IGMPV3_CHANGE_TO_EXCLUDE:
+		case IGMPV3_ALLOW_NEW_SOURCES:
+		case IGMPV3_BLOCK_OLD_SOURCES:
+			break;
+
+		default:
+			continue;
+		}
+
+		err = br_multicast_add_group(br, port, group);
+		if (err)
+			break;
+	}
+
+	return err;
+}
+
+static void br_multicast_mark_router(struct net_bridge *br,
+				     struct net_bridge_port *port)
+{
+	unsigned long now = jiffies;
+	struct hlist_node *p;
+	struct hlist_node **h;
+
+	if (!port) {
+		if (br->multicast_router == 1)
+			mod_timer(&br->multicast_router_timer,
+				  now + br->multicast_querier_interval);
+		return;
+	}
+
+	if (port->multicast_router != 1)
+		return;
+
+	if (!hlist_unhashed(&port->rlist))
+		goto timer;
+
+	for (h = &br->router_list.first;
+	     (p = *h) &&
+	     (unsigned long)container_of(p, struct net_bridge_port, rlist) >
+	     (unsigned long)port;
+	     h = &p->next)
+		;
+
+	port->rlist.pprev = h;
+	port->rlist.next = p;
+	rcu_assign_pointer(*h, &port->rlist);
+	if (p)
+		p->pprev = &port->rlist.next;
+
+timer:
+	mod_timer(&port->multicast_router_timer,
+		  now + br->multicast_querier_interval);
+}
+
+static void br_multicast_query_received(struct net_bridge *br,
+					struct net_bridge_port *port,
+					__be32 saddr)
+{
+	if (saddr)
+		mod_timer(&br->multicast_querier_timer,
+			  jiffies + br->multicast_querier_interval);
+	else if (timer_pending(&br->multicast_querier_timer))
+		return;
+
+	br_multicast_mark_router(br, port);
+}
+
+static int br_multicast_query(struct net_bridge *br,
+			      struct net_bridge_port *port,
+			      struct sk_buff *skb)
+{
+	struct iphdr *iph = ip_hdr(skb);
+	struct igmphdr *ih = igmp_hdr(skb);
+	struct net_bridge_mdb_entry *mp;
+	struct igmpv3_query *ih3;
+	struct net_bridge_port_group *p;
+	struct net_bridge_port_group **pp;
+	unsigned long max_delay;
+	unsigned long now = jiffies;
+	__be32 group;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev) ||
+	    (port && port->state == BR_STATE_DISABLED))
+		goto out;
+
+	br_multicast_query_received(br, port, iph->saddr);
+
+	group = ih->group;
+
+	if (skb->len == sizeof(*ih)) {
+		max_delay = ih->code * (HZ / IGMP_TIMER_SCALE);
+
+		if (!max_delay) {
+			max_delay = 10 * HZ;
+			group = 0;
+		}
+	} else {
+		if (!pskb_may_pull(skb, sizeof(struct igmpv3_query)))
+			return -EINVAL;
+
+		ih3 = igmpv3_query_hdr(skb);
+		if (ih3->nsrcs)
+			return 0;
+
+		max_delay = ih3->code ? 1 :
+			    IGMPV3_MRC(ih3->code) * (HZ / IGMP_TIMER_SCALE);
+	}
+
+	if (!group)
+		goto out;
+
+	mp = br_mdb_ip_get(br->mdb, group);
+	if (!mp)
+		goto out;
+
+	max_delay *= br->multicast_last_member_count;
+
+	if (!hlist_unhashed(&mp->mglist) &&
+	    (timer_pending(&mp->timer) ?
+	     time_after(mp->timer.expires, now + max_delay) :
+	     try_to_del_timer_sync(&mp->timer) >= 0))
+		mod_timer(&mp->timer, now + max_delay);
+
+	for (pp = &mp->ports; (p = *pp); pp = &p->next) {
+		if (timer_pending(&p->timer) ?
+		    time_after(p->timer.expires, now + max_delay) :
+		    try_to_del_timer_sync(&p->timer) >= 0)
+			mod_timer(&mp->timer, now + max_delay);
+	}
+
+out:
+	spin_unlock(&br->multicast_lock);
+	return 0;
+}
+
+static void br_multicast_leave_group(struct net_bridge *br,
+				     struct net_bridge_port *port,
+				     __be32 group)
+{
+	struct net_bridge_mdb_htable *mdb;
+	struct net_bridge_mdb_entry *mp;
+	struct net_bridge_port_group *p;
+	unsigned long now;
+	unsigned long time;
+
+	if (ipv4_is_local_multicast(group))
+		return;
+
+	spin_lock(&br->multicast_lock);
+	if (!netif_running(br->dev) ||
+	    (port && port->state == BR_STATE_DISABLED) ||
+	    timer_pending(&br->multicast_querier_timer))
+		goto out;
+
+	mdb = br->mdb;
+	mp = br_mdb_ip_get(mdb, group);
+	if (!mp)
+		goto out;
+
+	now = jiffies;
+	time = now + br->multicast_last_member_count *
+		     br->multicast_last_member_interval;
+
+	if (!port) {
+		if (!hlist_unhashed(&mp->mglist) &&
+		    (timer_pending(&mp->timer) ?
+		     time_after(mp->timer.expires, time) :
+		     try_to_del_timer_sync(&mp->timer) >= 0)) {
+			mod_timer(&mp->timer, time);
+
+			mp->queries_sent = 0;
+			mod_timer(&mp->query_timer, now);
+		}
+
+		goto out;
+	}
+
+	for (p = mp->ports; p; p = p->next) {
+		if (p->port != port)
+			continue;
+
+		if (!hlist_unhashed(&p->mglist) &&
+		    (timer_pending(&p->timer) ?
+		     time_after(p->timer.expires, time) :
+		     try_to_del_timer_sync(&p->timer) >= 0)) {
+			mod_timer(&p->timer, time);
+
+			p->queries_sent = 0;
+			mod_timer(&p->query_timer, now);
+		}
+
+		break;
+	}
+
+out:
+	spin_unlock(&br->multicast_lock);
+}
+
+static int br_multicast_ipv4_rcv(struct net_bridge *br,
+				 struct net_bridge_port *port,
+				 struct sk_buff *skb)
+{
+	struct sk_buff *skb2 = skb;
+	struct iphdr *iph;
+	struct igmphdr *ih;
+	unsigned len;
+	unsigned offset;
+	int err;
+
+	BR_INPUT_SKB_CB(skb)->igmp = 0;
+	BR_INPUT_SKB_CB(skb)->mrouters_only = 0;
+
+	/* We treat OOM as packet loss for now. */
+	if (!pskb_may_pull(skb, sizeof(*iph)))
+		return -EINVAL;
+
+	iph = ip_hdr(skb);
+
+	if (iph->ihl < 5 || iph->version != 4)
+		return -EINVAL;
+
+	if (!pskb_may_pull(skb, ip_hdrlen(skb)))
+		return -EINVAL;
+
+	iph = ip_hdr(skb);
+
+	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
+		return -EINVAL;
+
+	if (iph->protocol != IPPROTO_IGMP)
+		return 0;
+
+	len = ntohs(iph->tot_len);
+	if (skb->len < len || len < ip_hdrlen(skb))
+		return -EINVAL;
+
+	if (skb->len > len) {
+		skb2 = skb_clone(skb, GFP_ATOMIC);
+		if (!skb2)
+			return -ENOMEM;
+
+		err = pskb_trim_rcsum(skb2, len);
+		if (err)
+			return err;
+	}
+
+	len -= ip_hdrlen(skb2);
+	offset = skb_network_offset(skb2) + ip_hdrlen(skb2);
+	__skb_pull(skb2, offset);
+	skb_reset_transport_header(skb2);
+
+	err = -EINVAL;
+	if (!pskb_may_pull(skb2, sizeof(*ih)))
+		goto out;
+
+	iph = ip_hdr(skb2);
+
+	switch (skb2->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (!csum_fold(skb2->csum))
+			break;
+		/* fall through */
+	case CHECKSUM_NONE:
+		skb2->csum = 0;
+		if (skb_checksum_complete(skb2))
+			return -EINVAL;
+	}
+
+	err = 0;
+
+	BR_INPUT_SKB_CB(skb)->igmp = 1;
+	ih = igmp_hdr(skb2);
+
+	switch (ih->type) {
+	case IGMP_HOST_MEMBERSHIP_REPORT:
+	case IGMPV2_HOST_MEMBERSHIP_REPORT:
+		BR_INPUT_SKB_CB(skb2)->mrouters_only = 1;
+		err = br_multicast_add_group(br, port, ih->group);
+		break;
+	case IGMPV3_HOST_MEMBERSHIP_REPORT:
+		err = br_multicast_igmp3_report(br, port, skb2);
+		break;
+	case IGMP_HOST_MEMBERSHIP_QUERY:
+		err = br_multicast_query(br, port, skb2);
+		break;
+	case IGMP_HOST_LEAVE_MESSAGE:
+		br_multicast_leave_group(br, port, ih->group);
+		break;
+	}
+
+out:
+	__skb_push(skb2, offset);
+	if (skb2 != skb)
+		kfree_skb(skb2);
+	return err;
+}
+
+int br_multicast_rcv(struct net_bridge *br, struct net_bridge_port *port,
+		     struct sk_buff *skb)
+{
+	if (br->multicast_disabled)
+		return 0;
+
+	switch (skb->protocol) {
+	case htons(ETH_P_IP):
+		return br_multicast_ipv4_rcv(br, port, skb);
+	}
+
+	return 0;
+}
+
+static void br_multicast_query_expired(unsigned long data)
+{
+	struct net_bridge *br = (void *)data;
+
+	spin_lock(&br->multicast_lock);
+	if (br->multicast_startup_queries_sent <
+	    br->multicast_startup_query_count)
+		br->multicast_startup_queries_sent++;
+
+	br_multicast_send_query(br, NULL, br->multicast_startup_queries_sent);
+
+	spin_unlock(&br->multicast_lock);
+}
+
+void br_multicast_init(struct net_bridge *br)
+{
+	br->hash_elasticity = 4;
+	br->hash_max = 512;
+
+	br->multicast_router = 1;
+	br->multicast_last_member_count = 2;
+	br->multicast_startup_query_count = 2;
+
+	br->multicast_last_member_interval = HZ;
+	br->multicast_query_response_interval = 10 * HZ;
+	br->multicast_startup_query_interval = 125 * HZ / 4;
+	br->multicast_query_interval = 125 * HZ;
+	br->multicast_querier_interval = 255 * HZ;
+	br->multicast_membership_interval = 260 * HZ;
+
+	spin_lock_init(&br->multicast_lock);
+	setup_timer(&br->multicast_router_timer,
+		    br_multicast_local_router_expired, 0);
+	setup_timer(&br->multicast_querier_timer,
+		    br_multicast_local_router_expired, 0);
+	setup_timer(&br->multicast_query_timer, br_multicast_query_expired,
+		    (unsigned long)br);
+}
+
+void br_multicast_open(struct net_bridge *br)
+{
+	br->multicast_startup_queries_sent = 0;
+
+	if (br->multicast_disabled)
+		return;
+
+	mod_timer(&br->multicast_query_timer, jiffies);
+}
+
+void br_multicast_stop(struct net_bridge *br)
+{
+	struct net_bridge_mdb_htable *mdb;
+	struct net_bridge_mdb_entry *mp;
+	struct hlist_node *p, *n;
+	u32 ver;
+	int i;
+
+	del_timer_sync(&br->multicast_router_timer);
+	del_timer_sync(&br->multicast_querier_timer);
+	del_timer_sync(&br->multicast_query_timer);
+
+	spin_lock_bh(&br->multicast_lock);
+	mdb = br->mdb;
+	if (!mdb)
+		goto out;
+
+	br->mdb = NULL;
+
+	ver = mdb->ver;
+	for (i = 0; i < mdb->max; i++) {
+		hlist_for_each_entry_safe(mp, p, n, &mdb->mhash[i],
+					  hlist[ver]) {
+			del_timer(&mp->timer);
+			del_timer(&mp->query_timer);
+			call_rcu_bh(&mp->rcu, br_multicast_free_group);
+		}
+	}
+
+	if (mdb->old) {
+		spin_unlock_bh(&br->multicast_lock);
+		synchronize_rcu_bh();
+		spin_lock_bh(&br->multicast_lock);
+		WARN_ON(mdb->old);
+	}
+
+	mdb->old = mdb;
+	call_rcu_bh(&mdb->rcu, br_mdb_free);
+
+out:
+	spin_unlock_bh(&br->multicast_lock);
+}
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index fad5a2669d3..44345c9afdd 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);