openwrt-routing/batman-adv/patches/0010-multicast-optimization-for-bridges.patch

diff --git a/Makefile b/Makefile
index 5d2c058..fd6237c 100644
--- a/Makefile
+++ b/Makefile
@@ -52,6 +52,10 @@ ifneq ($(REVISION),)
 NOSTDINC_FLAGS += -DBATADV_SOURCE_VERSION=\"$(REVISION)\"
 endif
 
+include $(PWD)/compat-sources/Makefile
+
+export batman-adv-y
+
 BUILD_FLAGS := \
 	M=$(PWD)/net/batman-adv \
 	CONFIG_BATMAN_ADV=m \
diff --git a/compat-include/linux/etherdevice.h b/compat-include/linux/etherdevice.h
index f120202..721945c 100644
--- a/compat-include/linux/etherdevice.h
+++ b/compat-include/linux/etherdevice.h
@@ -35,6 +35,15 @@ static inline void batadv_eth_hw_addr_random(struct net_device *dev)
 
 #endif /* < KERNEL_VERSION(3, 4, 0) */
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 7, 0)
+
+static inline void eth_zero_addr(u8 *addr)
+{
+	memset(addr, 0x00, ETH_ALEN);
+}
+
+#endif /* < KERNEL_VERSION(3, 7, 0) */
+
 #if LINUX_VERSION_CODE < KERNEL_VERSION(3, 14, 0)
 
 #define ether_addr_equal_unaligned(_a, _b) (memcmp(_a, _b, ETH_ALEN) == 0)
diff --git a/compat-include/linux/if_bridge.h b/compat-include/linux/if_bridge.h
new file mode 100644
index 0000000..4d7ab67
--- /dev/null
+++ b/compat-include/linux/if_bridge.h
@@ -0,0 +1,65 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_LINUX_IF_BRIDGE_H_
+#define _NET_BATMAN_ADV_COMPAT_LINUX_IF_BRIDGE_H_
+
+#include <linux/version.h>
+#include_next <linux/if_bridge.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 0)
+
+struct br_ip {
+	union {
+		__be32  ip4;
+#if IS_ENABLED(CONFIG_IPV6)
+		struct in6_addr ip6;
+#endif
+	} u;
+	__be16          proto;
+	__u16           vid;
+};
+
+struct br_ip_list {
+	struct list_head list;
+	struct br_ip addr;
+};
+
+#endif /* < KERNEL_VERSION(3, 16, 0) */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 0) || \
+    LINUX_VERSION_CODE == KERNEL_VERSION(3, 16, 0) && \
+	(!IS_ENABLED(CONFIG_BRIDGE) || \
+	!IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING))
+
+#define br_multicast_list_adjacent(dev, br_ip_list) \
+	batadv_br_multicast_list_adjacent(dev, br_ip_list)
+
+#define br_multicast_has_querier_adjacent(dev, proto) \
+	batadv_br_multicast_has_querier_adjacent(dev, proto)
+
+static inline int batadv_br_multicast_list_adjacent(struct net_device *dev,
+			       struct list_head *br_ip_list)
+{
+	return 0;
+}
+
+static inline bool batadv_br_multicast_has_querier_adjacent(struct net_device *dev, int proto)
+{
+	return false;
+}
+
+#endif /* < KERNEL_VERSION(3, 16, 0) ||
+	* == KERNEL_VERSION(3, 16, 0) &&
+	* (!IS_ENABLED(CONFIG_BRIDGE) ||
+	* !IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING)) */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 17, 0)
+
+static inline bool br_multicast_has_querier_anywhere(struct net_device *dev, int proto)
+{
+	pr_warn_once("Old kernel detected (< 3.17) - multicast optimizations disabled\n");
+
+	return false;
+}
+
+#endif /* < KERNEL_VERSION(3, 17, 0) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_LINUX_IF_BRIDGE_H_ */
diff --git a/compat-include/linux/igmp.h b/compat-include/linux/igmp.h
new file mode 100644
index 0000000..f61ab79
--- /dev/null
+++ b/compat-include/linux/igmp.h
@@ -0,0 +1,13 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_LINUX_IGMP_H_
+#define _NET_BATMAN_ADV_COMPAT_LINUX_IGMP_H_
+
+#include <linux/version.h>
+#include_next <linux/igmp.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed);
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_LINUX_IGMP_H_ */
diff --git a/compat-include/linux/skbuff.h b/compat-include/linux/skbuff.h
index 96b018c..f4ae619 100644
--- a/compat-include/linux/skbuff.h
+++ b/compat-include/linux/skbuff.h
@@ -89,6 +89,20 @@ static inline void skb_reset_mac_len(struct sk_buff *skb)
 
 #define pskb_copy_for_clone pskb_copy
 
+__sum16 skb_checksum_simple_validate(struct sk_buff *skb);
+
+__sum16
+skb_checksum_validate(struct sk_buff *skb, int proto,
+		      __wsum (*compute_pseudo)(struct sk_buff *skb, int proto));
+
 #endif /* < KERNEL_VERSION(3, 16, 0) */
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
+				     unsigned int transport_len,
+				     __sum16(*skb_chkf)(struct sk_buff *skb));
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
+
 #endif	/* _NET_BATMAN_ADV_COMPAT_LINUX_SKBUFF_H_ */
diff --git a/compat-include/net/addrconf.h b/compat-include/net/addrconf.h
new file mode 100644
index 0000000..69c45d0
--- /dev/null
+++ b/compat-include/net/addrconf.h
@@ -0,0 +1,13 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_ADDRCONF_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_ADDRCONF_H_
+
+#include <linux/version.h>
+#include_next <net/addrconf.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed);
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_NET_ADDRCONF_H_ */
diff --git a/compat-include/net/ip6_checksum.h b/compat-include/net/ip6_checksum.h
new file mode 100644
index 0000000..fda0c07
--- /dev/null
+++ b/compat-include/net/ip6_checksum.h
@@ -0,0 +1,18 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_IP6_CHECKSUM_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_IP6_CHECKSUM_H_
+
+#include <linux/version.h>
+#include_next <net/ip6_checksum.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 0)
+
+static inline __wsum ip6_compute_pseudo(struct sk_buff *skb, int proto)
+{
+	return ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+					    &ipv6_hdr(skb)->daddr,
+					    skb->len, proto, 0));
+}
+
+#endif /* < KERNEL_VERSION(3, 16, 0) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_NET_IP6_CHECKSUM_H_ */
diff --git a/compat-include/net/ipv6.h b/compat-include/net/ipv6.h
new file mode 100644
index 0000000..1e190d8
--- /dev/null
+++ b/compat-include/net/ipv6.h
@@ -0,0 +1,17 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_IPV6_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_IPV6_H_
+
+#include <linux/version.h>
+#include_next <net/ipv6.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 3, 0)
+
+#define ipv6_skip_exthdr(skb, start, nexthdrp, frag_offp) \
+	({ \
+		(void)frag_offp; \
+		ipv6_skip_exthdr(skb, start, nexthdrp); \
+	})
+
+#endif /* < KERNEL_VERSION(3, 3, 0) */
+
+#endif /* _NET_BATMAN_ADV_COMPAT_NET_IPV6_H_ */
diff --git a/compat-sources/Makefile b/compat-sources/Makefile
new file mode 100644
index 0000000..c364ded
--- /dev/null
+++ b/compat-sources/Makefile
@@ -0,0 +1,3 @@
+batman-adv-y += ../../compat-sources/net/core/skbuff.o
+batman-adv-y += ../../compat-sources/net/ipv4/igmp.o
+batman-adv-y += ../../compat-sources/net/ipv6/mcast_snoop.o
diff --git a/compat-sources/net/core/skbuff.c b/compat-sources/net/core/skbuff.c
new file mode 100644
index 0000000..801c6cf
--- /dev/null
+++ b/compat-sources/net/core/skbuff.c
@@ -0,0 +1,214 @@
+/*
+ *	Routines having to do with the 'struct sk_buff' memory handlers.
+ *
+ *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *			Florian La Roche <rzsfl@rz.uni-sb.de>
+ *
+ *	Fixes:
+ *		Alan Cox	:	Fixed the worst of the load
+ *					balancer bugs.
+ *		Dave Platt	:	Interrupt stacking fix.
+ *	Richard Kooijman	:	Timestamp fixes.
+ *		Alan Cox	:	Changed buffer format.
+ *		Alan Cox	:	destructor hook for AF_UNIX etc.
+ *		Linus Torvalds	:	Better skb_clone.
+ *		Alan Cox	:	Added skb_copy.
+ *		Alan Cox	:	Added all the changed routines Linus
+ *					only put in the headers
+ *		Ray VanTassle	:	Fixed --skb->lock in free
+ *		Alan Cox	:	skb_copy copy arp field
+ *		Andi Kleen	:	slabified it.
+ *		Robert Olsson	:	Removed skb_head_pool
+ *
+ *	NOTE:
+ *		The __skb_ routines should be called with interrupts
+ *	disabled, or you better be *real* sure that the operation is atomic
+ *	with respect to whatever list is being frobbed (e.g. via lock_sock()
+ *	or via disabling bottom half handlers, etc).
+ *
+ *	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/ipv6.h>
+#include <linux/skbuff.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 0)
+
+/* Compare with:
+ * "bridge: multicast: call skb_checksum_{simple_, }validate"
+ */
+__sum16 skb_checksum_simple_validate(struct sk_buff *skb)
+{
+	switch (skb->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (!csum_fold(skb->csum))
+			break;
+		/* fall through */
+	case CHECKSUM_NONE:
+		skb->csum = 0;
+		if (skb_checksum_complete(skb))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* Watch out: Not as generic as upstream
+ * - redefines this method to only fit with ICMPV6
+ *
+ * Compare with:
+ * "bridge: multicast: call skb_checksum_{simple_, }validate"
+ */
+__sum16
+skb_checksum_validate(struct sk_buff *skb, int proto,
+		      __wsum (*compute_pseudo)(struct sk_buff *skb, int proto))
+{
+	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+
+	switch (skb->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, skb->len,
+				     IPPROTO_ICMPV6, skb->csum))
+			break;
+		/*FALLTHROUGH*/
+	case CHECKSUM_NONE:
+		skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
+							 &ip6h->daddr,
+							 skb->len,
+							 IPPROTO_ICMPV6, 0));
+		if (__skb_checksum_complete(skb))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+#endif /* < KERNEL_VERSION(3, 16, 0) */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+static inline void skb_postpush_rcsum(struct sk_buff *skb,
+                                   const void *start, unsigned int len)
+{
+	/* For performing the reverse operation to skb_postpull_rcsum(),
+	 * we can instead of ...
+	 *
+	 *   skb->csum = csum_add(skb->csum, csum_partial(start, len, 0));
+	 *
+	 * ... just use this equivalent version here to save a few
+	 * instructions. Feeding csum of 0 in csum_partial() and later
+	 * on adding skb->csum is equivalent to feed skb->csum in the
+	 * first place.
+	 */
+	if (skb->ip_summed == CHECKSUM_COMPLETE)
+		skb->csum = csum_partial(start, len, skb->csum);
+}
+
+/**
+ *	skb_push_rcsum - push skb and update receive checksum
+ *	@skb: buffer to update
+ *	@len: length of data pulled
+ *
+ *	This function performs an skb_push on the packet and updates
+ *	the CHECKSUM_COMPLETE checksum.  It should be used on
+ *	receive path processing instead of skb_push unless you know
+ *	that the checksum difference is zero (e.g., a valid IP header)
+ *	or you are setting ip_summed to CHECKSUM_NONE.
+ */
+static unsigned char *skb_push_rcsum(struct sk_buff *skb, unsigned len)
+{
+	skb_push(skb, len);
+	skb_postpush_rcsum(skb, skb->data, len);
+	return skb->data;
+}
+
+/**
+ * skb_checksum_maybe_trim - maybe trims the given skb
+ * @skb: the skb to check
+ * @transport_len: the data length beyond the network header
+ *
+ * Checks whether the given skb has data beyond the given transport length.
+ * If so, returns a cloned skb trimmed to this transport length.
+ * Otherwise returns the provided skb. Returns NULL in error cases
+ * (e.g. transport_len exceeds skb length or out-of-memory).
+ *
+ * Caller needs to set the skb transport header and release the returned skb.
+ * Provided skb is consumed.
+ */
+static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
+					       unsigned int transport_len)
+{
+	struct sk_buff *skb_chk;
+	unsigned int len = skb_transport_offset(skb) + transport_len;
+	int ret;
+
+	if (skb->len < len) {
+		kfree_skb(skb);
+		return NULL;
+	} else if (skb->len == len) {
+		return skb;
+	}
+
+	skb_chk = skb_clone(skb, GFP_ATOMIC);
+	kfree_skb(skb);
+
+	if (!skb_chk)
+		return NULL;
+
+	ret = pskb_trim_rcsum(skb_chk, len);
+	if (ret) {
+		kfree_skb(skb_chk);
+		return NULL;
+	}
+
+	return skb_chk;
+}
+
+/**
+ * skb_checksum_trimmed - validate checksum of an skb
+ * @skb: the skb to check
+ * @transport_len: the data length beyond the network header
+ * @skb_chkf: checksum function to use
+ *
+ * Applies the given checksum function skb_chkf to the provided skb.
+ * Returns a checked and maybe trimmed skb. Returns NULL on error.
+ *
+ * If the skb has data beyond the given transport length, then a
+ * trimmed & cloned skb is checked and returned.
+ *
+ * Caller needs to set the skb transport header and release the returned skb.
+ * Provided skb is consumed.
+ */
+struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
+				     unsigned int transport_len,
+				     __sum16(*skb_chkf)(struct sk_buff *skb))
+{
+	struct sk_buff *skb_chk;
+	unsigned int offset = skb_transport_offset(skb);
+	__sum16 ret;
+
+	skb_chk = skb_checksum_maybe_trim(skb, transport_len);
+	if (!skb_chk)
+		return NULL;
+
+	if (!pskb_may_pull(skb_chk, offset)) {
+		kfree_skb(skb_chk);
+		return NULL;
+	}
+
+	skb_pull_rcsum(skb_chk, offset);
+	ret = skb_chkf(skb_chk);
+	skb_push_rcsum(skb_chk, offset);
+
+	if (ret) {
+		kfree_skb(skb_chk);
+		return NULL;
+	}
+
+	return skb_chk;
+}
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
diff --git a/compat-sources/net/ipv4/igmp.c b/compat-sources/net/ipv4/igmp.c
new file mode 100644
index 0000000..457a05e
--- /dev/null
+++ b/compat-sources/net/ipv4/igmp.c
@@ -0,0 +1,241 @@
+/*
+ *	Linux NET3:	Internet Group Management Protocol  [IGMP]
+ *
+ *	This code implements the IGMP protocol as defined in RFC1112. There has
+ *	been a further revision of this protocol since which is now supported.
+ *
+ *	If you have trouble with this module be careful what gcc you have used,
+ *	the older version didn't come out right using gcc 2.5.8, the newer one
+ *	seems to fall out with gcc 2.6.2.
+ *
+ *	Authors:
+ *		Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *
+ *	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.
+ *
+ *	Fixes:
+ *
+ *		Alan Cox	:	Added lots of __inline__ to optimise
+ *					the memory usage of all the tiny little
+ *					functions.
+ *		Alan Cox	:	Dumped the header building experiment.
+ *		Alan Cox	:	Minor tweaks ready for multicast routing
+ *					and extended IGMP protocol.
+ *		Alan Cox	:	Removed a load of inline directives. Gcc 2.5.8
+ *					writes utterly bogus code otherwise (sigh)
+ *					fixed IGMP loopback to behave in the manner
+ *					desired by mrouted, fixed the fact it has been
+ *					broken since 1.3.6 and cleaned up a few minor
+ *					points.
+ *
+ *		Chih-Jen Chang	:	Tried to revise IGMP to Version 2
+ *		Tsu-Sheng Tsao		E-mail: chihjenc@scf.usc.edu and tsusheng@scf.usc.edu
+ *					The enhancements are mainly based on Steve Deering's
+ * 					ipmulti-3.5 source code.
+ *		Chih-Jen Chang	:	Added the igmp_get_mrouter_info and
+ *		Tsu-Sheng Tsao		igmp_set_mrouter_info to keep track of
+ *					the mrouted version on that device.
+ *		Chih-Jen Chang	:	Added the max_resp_time parameter to
+ *		Tsu-Sheng Tsao		igmp_heard_query(). Using this parameter
+ *					to identify the multicast router version
+ *					and do what the IGMP version 2 specified.
+ *		Chih-Jen Chang	:	Added a timer to revert to IGMP V2 router
+ *		Tsu-Sheng Tsao		if the specified time expired.
+ *		Alan Cox	:	Stop IGMP from 0.0.0.0 being accepted.
+ *		Alan Cox	:	Use GFP_ATOMIC in the right places.
+ *		Christian Daudt :	igmp timer wasn't set for local group
+ *					memberships but was being deleted,
+ *					which caused a "del_timer() called
+ *					from %p with timer not initialized\n"
+ *					message (960131).
+ *		Christian Daudt :	removed del_timer from
+ *					igmp_timer_expire function (960205).
+ *             Christian Daudt :       igmp_heard_report now only calls
+ *                                     igmp_timer_expire if tm->running is
+ *                                     true (960216).
+ *		Malcolm Beattie :	ttl comparison wrong in igmp_rcv made
+ *					igmp_heard_query never trigger. Expiry
+ *					miscalculation fixed in igmp_heard_query
+ *					and random() made to return unsigned to
+ *					prevent negative expiry times.
+ *		Alexey Kuznetsov:	Wrong group leaving behaviour, backport
+ *					fix from pending 2.1.x patches.
+ *		Alan Cox:		Forget to enable FDDI support earlier.
+ *		Alexey Kuznetsov:	Fixed leaving groups on device down.
+ *		Alexey Kuznetsov:	Accordance to igmp-v2-06 draft.
+ *		David L Stevens:	IGMPv3 support, with help from
+ *					Vinay Kulkarni
+ */
+
+#include <linux/igmp.h>
+#include <linux/ip.h>
+#include <linux/skbuff.h>
+#include <net/ip.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+static int ip_mc_check_iphdr(struct sk_buff *skb)
+{
+	const struct iphdr *iph;
+	unsigned int len;
+	unsigned int offset = skb_network_offset(skb) + sizeof(*iph);
+
+	if (!pskb_may_pull(skb, offset))
+		return -EINVAL;
+
+	iph = ip_hdr(skb);
+
+	if (iph->version != 4 || ip_hdrlen(skb) < sizeof(*iph))
+		return -EINVAL;
+
+	offset += ip_hdrlen(skb) - sizeof(*iph);
+
+	if (!pskb_may_pull(skb, offset))
+		return -EINVAL;
+
+	iph = ip_hdr(skb);
+
+	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
+		return -EINVAL;
+
+	len = skb_network_offset(skb) + ntohs(iph->tot_len);
+	if (skb->len < len || len < offset)
+		return -EINVAL;
+
+	skb_set_transport_header(skb, offset);
+
+	return 0;
+}
+
+static int ip_mc_check_igmp_reportv3(struct sk_buff *skb)
+{
+	unsigned int len = skb_transport_offset(skb);
+
+	len += sizeof(struct igmpv3_report);
+
+	return pskb_may_pull(skb, len) ? 0 : -EINVAL;
+}
+
+static int ip_mc_check_igmp_query(struct sk_buff *skb)
+{
+	unsigned int len = skb_transport_offset(skb);
+
+	len += sizeof(struct igmphdr);
+	if (skb->len < len)
+		return -EINVAL;
+
+	/* IGMPv{1,2}? */
+	if (skb->len != len) {
+		/* or IGMPv3? */
+		len += sizeof(struct igmpv3_query) - sizeof(struct igmphdr);
+		if (skb->len < len || !pskb_may_pull(skb, len))
+			return -EINVAL;
+	}
+
+	/* RFC2236+RFC3376 (IGMPv2+IGMPv3) require the multicast link layer
+	 * all-systems destination addresses (224.0.0.1) for general queries
+	 */
+	if (!igmp_hdr(skb)->group &&
+	    ip_hdr(skb)->daddr != htonl(INADDR_ALLHOSTS_GROUP))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ip_mc_check_igmp_msg(struct sk_buff *skb)
+{
+	switch (igmp_hdr(skb)->type) {
+	case IGMP_HOST_LEAVE_MESSAGE:
+	case IGMP_HOST_MEMBERSHIP_REPORT:
+	case IGMPV2_HOST_MEMBERSHIP_REPORT:
+		/* fall through */
+		return 0;
+	case IGMPV3_HOST_MEMBERSHIP_REPORT:
+		return ip_mc_check_igmp_reportv3(skb);
+	case IGMP_HOST_MEMBERSHIP_QUERY:
+		return ip_mc_check_igmp_query(skb);
+	default:
+		return -ENOMSG;
+	}
+}
+
+static inline __sum16 ip_mc_validate_checksum(struct sk_buff *skb)
+{
+	return skb_checksum_simple_validate(skb);
+}
+
+static int __ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+
+{
+	struct sk_buff *skb_chk;
+	unsigned int transport_len;
+	unsigned int len = skb_transport_offset(skb) + sizeof(struct igmphdr);
+	int ret;
+
+	transport_len = ntohs(ip_hdr(skb)->tot_len) - ip_hdrlen(skb);
+
+	skb_get(skb);
+	skb_chk = skb_checksum_trimmed(skb, transport_len,
+				       ip_mc_validate_checksum);
+	if (!skb_chk)
+		return -EINVAL;
+
+	if (!pskb_may_pull(skb_chk, len)) {
+		kfree_skb(skb_chk);
+		return -EINVAL;
+	}
+
+	ret = ip_mc_check_igmp_msg(skb_chk);
+	if (ret) {
+		kfree_skb(skb_chk);
+		return ret;
+	}
+
+	if (skb_trimmed)
+		*skb_trimmed = skb_chk;
+	else
+		kfree_skb(skb_chk);
+
+	return 0;
+}
+
+/**
+ * ip_mc_check_igmp - checks whether this is a sane IGMP packet
+ * @skb: the skb to validate
+ * @skb_trimmed: to store an skb pointer trimmed to IPv4 packet tail (optional)
+ *
+ * Checks whether an IPv4 packet is a valid IGMP packet. If so sets
+ * skb network and transport headers accordingly and returns zero.
+ *
+ * -EINVAL: A broken packet was detected, i.e. it violates some internet
+ *  standard
+ * -ENOMSG: IP header validation succeeded but it is not an IGMP packet.
+ * -ENOMEM: A memory allocation failure happened.
+ *
+ * Optionally, an skb pointer might be provided via skb_trimmed (or set it
+ * to NULL): After parsing an IGMP packet successfully it will point to
+ * an skb which has its tail aligned to the IP packet end. This might
+ * either be the originally provided skb or a trimmed, cloned version if
+ * the skb frame had data beyond the IP packet. A cloned skb allows us
+ * to leave the original skb and its full frame unchanged (which might be
+ * desirable for layer 2 frame jugglers).
+ *
+ * The caller needs to release a reference count from any returned skb_trimmed.
+ */
+int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+{
+	int ret = ip_mc_check_iphdr(skb);
+
+	if (ret < 0)
+		return ret;
+
+	if (ip_hdr(skb)->protocol != IPPROTO_IGMP)
+		return -ENOMSG;
+
+	return __ip_mc_check_igmp(skb, skb_trimmed);
+}
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
diff --git a/compat-sources/net/ipv6/mcast_snoop.c b/compat-sources/net/ipv6/mcast_snoop.c
new file mode 100644
index 0000000..3f46ed3
--- /dev/null
+++ b/compat-sources/net/ipv6/mcast_snoop.c
@@ -0,0 +1,216 @@
+/* Copyright (C) 2010: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+ * Copyright (C) 2015: Linus Lüssing <linus.luessing@c0d3.blue>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Based on the MLD support added to br_multicast.c by YOSHIFUJI Hideaki.
+ */
+
+#include <linux/skbuff.h>
+#include <net/ipv6.h>
+#include <net/mld.h>
+#include <net/addrconf.h>
+#include <net/ip6_checksum.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+static int ipv6_mc_check_ip6hdr(struct sk_buff *skb)
+{
+	const struct ipv6hdr *ip6h;
+	unsigned int len;
+	unsigned int offset = skb_network_offset(skb) + sizeof(*ip6h);
+
+	if (!pskb_may_pull(skb, offset))
+		return -EINVAL;
+
+	ip6h = ipv6_hdr(skb);
+
+	if (ip6h->version != 6)
+		return -EINVAL;
+
+	len = offset + ntohs(ip6h->payload_len);
+	if (skb->len < len || len <= offset)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ipv6_mc_check_exthdrs(struct sk_buff *skb)
+{
+	const struct ipv6hdr *ip6h;
+	int offset;
+	u8 nexthdr;
+	__be16 frag_off;
+
+	ip6h = ipv6_hdr(skb);
+
+	if (ip6h->nexthdr != IPPROTO_HOPOPTS)
+		return -ENOMSG;
+
+	nexthdr = ip6h->nexthdr;
+	offset = skb_network_offset(skb) + sizeof(*ip6h);
+	offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
+
+	if (offset < 0)
+		return -EINVAL;
+
+	if (nexthdr != IPPROTO_ICMPV6)
+		return -ENOMSG;
+
+	skb_set_transport_header(skb, offset);
+
+	return 0;
+}
+
+static int ipv6_mc_check_mld_reportv2(struct sk_buff *skb)
+{
+	unsigned int len = skb_transport_offset(skb);
+
+	len += sizeof(struct mld2_report);
+
+	return pskb_may_pull(skb, len) ? 0 : -EINVAL;
+}
+
+static int ipv6_mc_check_mld_query(struct sk_buff *skb)
+{
+	struct mld_msg *mld;
+	unsigned int len = skb_transport_offset(skb);
+
+	/* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */
+	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL))
+		return -EINVAL;
+
+	len += sizeof(struct mld_msg);
+	if (skb->len < len)
+		return -EINVAL;
+
+	/* MLDv1? */
+	if (skb->len != len) {
+		/* or MLDv2? */
+		len += sizeof(struct mld2_query) - sizeof(struct mld_msg);
+		if (skb->len < len || !pskb_may_pull(skb, len))
+			return -EINVAL;
+	}
+
+	mld = (struct mld_msg *)skb_transport_header(skb);
+
+	/* RFC2710+RFC3810 (MLDv1+MLDv2) require the multicast link layer
+	 * all-nodes destination address (ff02::1) for general queries
+	 */
+	if (ipv6_addr_any(&mld->mld_mca) &&
+	    !ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ipv6_mc_check_mld_msg(struct sk_buff *skb)
+{
+	struct mld_msg *mld = (struct mld_msg *)skb_transport_header(skb);
+
+	switch (mld->mld_type) {
+	case ICMPV6_MGM_REDUCTION:
+	case ICMPV6_MGM_REPORT:
+		/* fall through */
+		return 0;
+	case ICMPV6_MLD2_REPORT:
+		return ipv6_mc_check_mld_reportv2(skb);
+	case ICMPV6_MGM_QUERY:
+		return ipv6_mc_check_mld_query(skb);
+	default:
+		return -ENOMSG;
+	}
+}
+
+static inline __sum16 ipv6_mc_validate_checksum(struct sk_buff *skb)
+{
+	return skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo);
+}
+
+static int __ipv6_mc_check_mld(struct sk_buff *skb,
+			       struct sk_buff **skb_trimmed)
+
+{
+	struct sk_buff *skb_chk = NULL;
+	unsigned int transport_len;
+	unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg);
+	int ret;
+
+	transport_len = ntohs(ipv6_hdr(skb)->payload_len);
+	transport_len -= skb_transport_offset(skb) - sizeof(struct ipv6hdr);
+
+	skb_get(skb);
+	skb_chk = skb_checksum_trimmed(skb, transport_len,
+				       ipv6_mc_validate_checksum);
+	if (!skb_chk)
+		return -EINVAL;
+
+	if (!pskb_may_pull(skb_chk, len)) {
+		kfree_skb(skb_chk);
+		return -EINVAL;
+	}
+
+	ret = ipv6_mc_check_mld_msg(skb_chk);
+	if (ret) {
+		kfree_skb(skb_chk);
+		return ret;
+	}
+
+	if (skb_trimmed)
+		*skb_trimmed = skb_chk;
+	else
+		kfree_skb(skb_chk);
+
+	return 0;
+}
+
+/**
+ * ipv6_mc_check_mld - checks whether this is a sane MLD packet
+ * @skb: the skb to validate
+ * @skb_trimmed: to store an skb pointer trimmed to IPv6 packet tail (optional)
+ *
+ * Checks whether an IPv6 packet is a valid MLD packet. If so sets
+ * skb network and transport headers accordingly and returns zero.
+ *
+ * -EINVAL: A broken packet was detected, i.e. it violates some internet
+ *  standard
+ * -ENOMSG: IP header validation succeeded but it is not an MLD packet.
+ * -ENOMEM: A memory allocation failure happened.
+ *
+ * Optionally, an skb pointer might be provided via skb_trimmed (or set it
+ * to NULL): After parsing an MLD packet successfully it will point to
+ * an skb which has its tail aligned to the IP packet end. This might
+ * either be the originally provided skb or a trimmed, cloned version if
+ * the skb frame had data beyond the IP packet. A cloned skb allows us
+ * to leave the original skb and its full frame unchanged (which might be
+ * desirable for layer 2 frame jugglers).
+ *
+ * The caller needs to release a reference count from any returned skb_trimmed.
+ */
+int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+{
+	int ret;
+
+	ret = ipv6_mc_check_ip6hdr(skb);
+	if (ret < 0)
+		return ret;
+
+	ret = ipv6_mc_check_exthdrs(skb);
+	if (ret < 0)
+		return ret;
+
+	return __ipv6_mc_check_mld(skb, skb_trimmed);
+}
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
diff --git a/net/batman-adv/debugfs.c b/net/batman-adv/debugfs.c
index 48253cf..9bf37bf 100644
--- a/net/batman-adv/debugfs.c
+++ b/net/batman-adv/debugfs.c
@@ -48,6 +48,7 @@
 #include "distributed-arp-table.h"
 #include "gateway_client.h"
 #include "icmp_socket.h"
+#include "multicast.h"
 #include "network-coding.h"
 #include "originator.h"
 #include "translation-table.h"
@@ -363,6 +364,20 @@ static int batadv_nc_nodes_open(struct inode *inode, struct file *file)
 }
 #endif
 
+#ifdef CONFIG_BATMAN_ADV_MCAST
+/**
+ * batadv_mcast_flags_open - prepare file handler for reads from mcast_flags
+ * @inode: inode which was opened
+ * @file: file handle to be initialized
+ */
+static int batadv_mcast_flags_open(struct inode *inode, struct file *file)
+{
+	struct net_device *net_dev = (struct net_device *)inode->i_private;
+
+	return single_open(file, batadv_mcast_flags_seq_print_text, net_dev);
+}
+#endif
+
 #define BATADV_DEBUGINFO(_name, _mode, _open)		\
 struct batadv_debuginfo batadv_debuginfo_##_name = {	\
 	.attr = { .name = __stringify(_name),		\
@@ -404,6 +419,9 @@ static BATADV_DEBUGINFO(transtable_local, S_IRUGO,
 #ifdef CONFIG_BATMAN_ADV_NC
 static BATADV_DEBUGINFO(nc_nodes, S_IRUGO, batadv_nc_nodes_open);
 #endif
+#ifdef CONFIG_BATMAN_ADV_MCAST
+static BATADV_DEBUGINFO(mcast_flags, S_IRUGO, batadv_mcast_flags_open);
+#endif
 
 static struct batadv_debuginfo *batadv_mesh_debuginfos[] = {
 	&batadv_debuginfo_neighbors,
@@ -421,6 +439,9 @@ static struct batadv_debuginfo *batadv_mesh_debuginfos[] = {
 #ifdef CONFIG_BATMAN_ADV_NC
 	&batadv_debuginfo_nc_nodes,
 #endif
+#ifdef CONFIG_BATMAN_ADV_MCAST
+	&batadv_debuginfo_mcast_flags,
+#endif
 	NULL,
 };
 
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index db45336..c4572b3 100644
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -227,6 +227,7 @@ __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr);
  * @BATADV_DBG_BLA: bridge loop avoidance messages
  * @BATADV_DBG_DAT: ARP snooping and DAT related messages
  * @BATADV_DBG_NC: network coding related messages
+ * @BATADV_DBG_MCAST: multicast related messages
  * @BATADV_DBG_ALL: the union of all the above log levels
  */
 enum batadv_dbg_level {
@@ -236,7 +237,8 @@ enum batadv_dbg_level {
 	BATADV_DBG_BLA    = BIT(3),
 	BATADV_DBG_DAT    = BIT(4),
 	BATADV_DBG_NC	  = BIT(5),
-	BATADV_DBG_ALL    = 63,
+	BATADV_DBG_MCAST  = BIT(6),
+	BATADV_DBG_ALL    = 127,
 };
 
 #ifdef CONFIG_BATMAN_ADV_DEBUG
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 8caa2c7..0d732d7 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -25,7 +25,10 @@
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
 #include <linux/fs.h>
+#include <linux/icmpv6.h>
+#include <linux/if_bridge.h>
 #include <linux/if_ether.h>
+#include <linux/igmp.h>
 #include <linux/in6.h>
 #include <linux/in.h>
 #include <linux/ip.h>
@@ -43,18 +46,55 @@
 #include <linux/string.h>
 #include <linux/types.h>
 #include <net/addrconf.h>
+#include <net/ip.h>
 #include <net/ipv6.h>
+#include <net/mld.h>
 
+#include "hard-interface.h"
+#include "hash.h"
 #include "packet.h"
 #include "translation-table.h"
 
 /**
+ * batadv_mcast_get_bridge - get the bridge on top of the softif if it exists
+ * @soft_iface: netdev struct of the mesh interface
+ *
+ * If the given soft interface has a bridge on top then the refcount
+ * of the according net device is increased.
+ *
+ * Return: NULL if no such bridge exists. Otherwise the net device of the
+ * bridge.
+ */
+static struct net_device *batadv_mcast_get_bridge(struct net_device *soft_iface)
+{
+	struct net_device *upper = soft_iface;
+
+	rcu_read_lock();
+	do {
+		upper = netdev_master_upper_dev_get_rcu(upper);
+	} while (upper && !(upper->priv_flags & IFF_EBRIDGE));
+
+	if (upper)
+		dev_hold(upper);
+	rcu_read_unlock();
+
+	return upper;
+}
+
+/**
  * batadv_mcast_mla_softif_get - get softif multicast listeners
  * @dev: the device to collect multicast addresses from
  * @mcast_list: a list to put found addresses into
  *
- * Collect multicast addresses of the local multicast listeners
- * on the given soft interface, dev, in the given mcast_list.
+ * Collects multicast addresses of multicast listeners residing
+ * on this kernel on the given soft interface, dev, in
+ * the given mcast_list. In general, multicast listeners provided by
+ * your multicast receiving applications run directly on this node.
+ *
+ * If there is a bridge interface on top of dev, collects from that one
+ * instead. Just like with IP addresses and routes, multicast listeners
+ * will(/should) register to the bridge interface instead of an
+ * enslaved bat0.
  *
  * Return: -ENOMEM on memory allocation error or the number of
  * items added to the mcast_list otherwise.
@@ -62,12 +102,13 @@
 static int batadv_mcast_mla_softif_get(struct net_device *dev,
 				       struct hlist_head *mcast_list)
 {
+	struct net_device *bridge = batadv_mcast_get_bridge(dev);
 	struct netdev_hw_addr *mc_list_entry;
 	struct batadv_hw_addr *new;
 	int ret = 0;
 
-	netif_addr_lock_bh(dev);
-	netdev_for_each_mc_addr(mc_list_entry, dev) {
+	netif_addr_lock_bh(bridge ? bridge : dev);
+	netdev_for_each_mc_addr(mc_list_entry, bridge ? bridge : dev) {
 		new = kmalloc(sizeof(*new), GFP_ATOMIC);
 		if (!new) {
 			ret = -ENOMEM;
@@ -78,7 +119,10 @@ static int batadv_mcast_mla_softif_get(struct net_device *dev,
 		hlist_add_head(&new->list, mcast_list);
 		ret++;
 	}
-	netif_addr_unlock_bh(dev);
+	netif_addr_unlock_bh(bridge ? bridge : dev);
+
+	if (bridge)
+		dev_put(bridge);
 
 	return ret;
 }
@@ -104,6 +148,83 @@ static bool batadv_mcast_mla_is_duplicate(u8 *mcast_addr,
 }
 
 /**
+ * batadv_mcast_mla_br_addr_cpy - copy a bridge multicast address
+ * @dst: destination to write to - a multicast MAC address
+ * @src: source to read from - a multicast IP address
+ *
+ * Converts a given multicast IPv4/IPv6 address from a bridge
+ * to its matching multicast MAC address and copies it into the given
+ * destination buffer.
+ *
+ * Caller needs to make sure the destination buffer can hold
+ * at least ETH_ALEN bytes.
+ */
+static void batadv_mcast_mla_br_addr_cpy(char *dst, const struct br_ip *src)
+{
+	if (src->proto == htons(ETH_P_IP))
+		ip_eth_mc_map(src->u.ip4, dst);
+#if IS_ENABLED(CONFIG_IPV6)
+	else if (src->proto == htons(ETH_P_IPV6))
+		ipv6_eth_mc_map(&src->u.ip6, dst);
+#endif
+	else
+		eth_zero_addr(dst);
+}
+
+/**
+ * batadv_mcast_mla_bridge_get - get bridged-in multicast listeners
+ * @dev: a bridge slave whose bridge to collect multicast addresses from
+ * @mcast_list: a list to put found addresses into
+ *
+ * Collects multicast addresses of multicast listeners residing
+ * on foreign, non-mesh devices which we gave access to our mesh via
+ * a bridge on top of the given soft interface, dev, in the given
+ * mcast_list.
+ *
+ * Return: -ENOMEM on memory allocation error or the number of
+ * items added to the mcast_list otherwise.
+ */
+static int batadv_mcast_mla_bridge_get(struct net_device *dev,
+				       struct hlist_head *mcast_list)
+{
+	struct list_head bridge_mcast_list = LIST_HEAD_INIT(bridge_mcast_list);
+	struct br_ip_list *br_ip_entry, *tmp;
+	struct batadv_hw_addr *new;
+	u8 mcast_addr[ETH_ALEN];
+	int ret;
+
+	/* we don't need to detect these devices/listeners, the IGMP/MLD
+	 * snooping code of the Linux bridge already does that for us
+	 */
+	ret = br_multicast_list_adjacent(dev, &bridge_mcast_list);
+	if (ret < 0)
+		goto out;
+
+	list_for_each_entry(br_ip_entry, &bridge_mcast_list, list) {
+		batadv_mcast_mla_br_addr_cpy(mcast_addr, &br_ip_entry->addr);
+		if (batadv_mcast_mla_is_duplicate(mcast_addr, mcast_list))
+			continue;
+
+		new = kmalloc(sizeof(*new), GFP_ATOMIC);
+		if (!new) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		ether_addr_copy(new->addr, mcast_addr);
+		hlist_add_head(&new->list, mcast_list);
+	}
+
+out:
+	list_for_each_entry_safe(br_ip_entry, tmp, &bridge_mcast_list, list) {
+		list_del(&br_ip_entry->list);
+		kfree(br_ip_entry);
+	}
+
+	return ret;
+}
+
+/**
  * batadv_mcast_mla_list_free - free a list of multicast addresses
  * @bat_priv: the bat priv with all the soft interface information
  * @mcast_list: the list to free
@@ -214,44 +335,195 @@ static bool batadv_mcast_has_bridge(struct batadv_priv *bat_priv)
 }
 
 /**
+ * batadv_mcast_querier_log - debug output regarding the querier status on link
+ * @bat_priv: the bat priv with all the soft interface information
+ * @str_proto: a string for the querier protocol (e.g. "IGMP" or "MLD")
+ * @old_state: the previous querier state on our link
+ * @new_state: the new querier state on our link
+ *
+ * Outputs debug messages to the logging facility with log level 'mcast'
+ * regarding changes to the querier status on the link which are relevant
+ * to our multicast optimizations.
+ *
+ * Usually this is about whether a querier appeared or vanished in
+ * our mesh or whether the querier is in the suboptimal position of being
+ * behind our local bridge segment: Snooping switches will directly
+ * forward listener reports to the querier, therefore batman-adv and
+ * the bridge will potentially not see these listeners - the querier is
+ * potentially shadowing listeners from us then.
+ *
+ * This is only interesting for nodes with a bridge on top of their
+ * soft interface.
+ */
+static void
+batadv_mcast_querier_log(struct batadv_priv *bat_priv, char *str_proto,
+			 struct batadv_mcast_querier_state *old_state,
+			 struct batadv_mcast_querier_state *new_state)
+{
+	if (!old_state->exists && new_state->exists)
+		batadv_info(bat_priv->soft_iface, "%s Querier appeared\n",
+			    str_proto);
+	else if (old_state->exists && !new_state->exists)
+		batadv_info(bat_priv->soft_iface,
+			    "%s Querier disappeared - multicast optimizations disabled\n",
+			    str_proto);
+	else if (!bat_priv->mcast.bridged && !new_state->exists)
+		batadv_info(bat_priv->soft_iface,
+			    "No %s Querier present - multicast optimizations disabled\n",
+			    str_proto);
+
+	if (new_state->exists) {
+		if ((!old_state->shadowing && new_state->shadowing) ||
+		    (!old_state->exists && new_state->shadowing))
+			batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+				   "%s Querier is behind our bridged segment: Might shadow listeners\n",
+				   str_proto);
+		else if (old_state->shadowing && !new_state->shadowing)
+			batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+				   "%s Querier is not behind our bridged segment\n",
+				   str_proto);
+	}
+}
+
+/**
+ * batadv_mcast_bridge_log - debug output for topology changes in bridged setups
+ * @bat_priv: the bat priv with all the soft interface information
+ * @bridged: a flag about whether the soft interface is currently bridged or not
+ * @querier_ipv4: (maybe) new status of a potential, selected IGMP querier
+ * @querier_ipv6: (maybe) new status of a potential, selected MLD querier
+ *
+ * If no bridges are ever used on this node, then this function does nothing.
+ *
+ * Otherwise this function outputs debug information to the 'mcast' log level
+ * which might be relevant to our multicast optimizations.
+ *
+ * More precisely, it outputs information when a bridge interface is added or
+ * removed from a soft interface. And when a bridge is present, it further
+ * outputs information about the querier state which is relevant for the
+ * multicast flags this node is going to set.
+ */
+static void
+batadv_mcast_bridge_log(struct batadv_priv *bat_priv, bool bridged,
+			struct batadv_mcast_querier_state *querier_ipv4,
+			struct batadv_mcast_querier_state *querier_ipv6)
+{
+	if (!bat_priv->mcast.bridged && bridged)
+		batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+			   "Bridge added: Setting Unsnoopables(U)-flag\n");
+	else if (bat_priv->mcast.bridged && !bridged)
+		batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+			   "Bridge removed: Unsetting Unsnoopables(U)-flag\n");
+
+	if (bridged) {
+		batadv_mcast_querier_log(bat_priv, "IGMP",
+					 &bat_priv->mcast.querier_ipv4,
+					 querier_ipv4);
+		batadv_mcast_querier_log(bat_priv, "MLD",
+					 &bat_priv->mcast.querier_ipv6,
+					 querier_ipv6);
+	}
+}
+
+/**
+ * batadv_mcast_flags_logs - output debug information about mcast flag changes
+ * @bat_priv: the bat priv with all the soft interface information
+ * @mcast_flags: flags indicating the new multicast state
+ *
+ * Whenever the multicast flags this nodes announces changes (@mcast_flags vs.
+ * bat_priv->mcast.flags), this notifies userspace via the 'mcast' log level.
+ */
+static void batadv_mcast_flags_log(struct batadv_priv *bat_priv, u8 flags)
+{
+	u8 old_flags = bat_priv->mcast.flags;
+	char str_old_flags[] = "[...]";
+
+	sprintf(str_old_flags, "[%c%c%c]",
+		old_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES ? 'U' : '.',
+		old_flags & BATADV_MCAST_WANT_ALL_IPV4 ? '4' : '.',
+		old_flags & BATADV_MCAST_WANT_ALL_IPV6 ? '6' : '.');
+
+	batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+		   "Changing multicast flags from '%s' to '[%c%c%c]'\n",
+		   bat_priv->mcast.enabled ? str_old_flags : "<undefined>",
+		   flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES ? 'U' : '.',
+		   flags & BATADV_MCAST_WANT_ALL_IPV4 ? '4' : '.',
+		   flags & BATADV_MCAST_WANT_ALL_IPV6 ? '6' : '.');
+}
+
+/**
  * batadv_mcast_mla_tvlv_update - update multicast tvlv
  * @bat_priv: the bat priv with all the soft interface information
  *
  * Updates the own multicast tvlv with our current multicast related settings,
  * capabilities and inabilities.
  *
- * Return: true if the tvlv container is registered afterwards. Otherwise
- * returns false.
+ * Return: false if we want all IPv4 && IPv6 multicast traffic and true
+ * otherwise.
  */
 static bool batadv_mcast_mla_tvlv_update(struct batadv_priv *bat_priv)
 {
 	struct batadv_tvlv_mcast_data mcast_data;
+	struct batadv_mcast_querier_state querier4 = {false, false};
+	struct batadv_mcast_querier_state querier6 = {false, false};
+	struct net_device *dev = bat_priv->soft_iface;
+	bool bridged;
 
 	mcast_data.flags = BATADV_NO_FLAGS;
 	memset(mcast_data.reserved, 0, sizeof(mcast_data.reserved));
 
-	/* Avoid attaching MLAs, if there is a bridge on top of our soft
-	 * interface, we don't support that yet (TODO)
+	bridged = batadv_mcast_has_bridge(bat_priv);
+	if (!bridged)
+		goto update;
+
+#if !IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING)
+	pr_warn_once("No bridge IGMP snooping compiled - multicast optimizations disabled\n");
+#endif
+
+	querier4.exists = br_multicast_has_querier_anywhere(dev, ETH_P_IP);
+	querier4.shadowing = br_multicast_has_querier_adjacent(dev, ETH_P_IP);
+
+	querier6.exists = br_multicast_has_querier_anywhere(dev, ETH_P_IPV6);
+	querier6.shadowing = br_multicast_has_querier_adjacent(dev, ETH_P_IPV6);
+
+	mcast_data.flags |= BATADV_MCAST_WANT_ALL_UNSNOOPABLES;
+
+	/* 1) If no querier exists at all, then multicast listeners on
+	 *    our local TT clients behind the bridge will keep silent.
+	 * 2) If the selected querier is on one of our local TT clients,
+	 *    behind the bridge, then this querier might shadow multicast
+	 *    listeners on our local TT clients, behind this bridge.
+	 *
+	 * In both cases, we will signalize other batman nodes that
+	 * we need all multicast traffic of the according protocol.
 	 */
-	if (batadv_mcast_has_bridge(bat_priv)) {
-		if (bat_priv->mcast.enabled) {
-			batadv_tvlv_container_unregister(bat_priv,
-							 BATADV_TVLV_MCAST, 1);
-			bat_priv->mcast.enabled = false;
-		}
+	if (!querier4.exists || querier4.shadowing)
+		mcast_data.flags |= BATADV_MCAST_WANT_ALL_IPV4;
 
-		return false;
-	}
+	if (!querier6.exists || querier6.shadowing)
+		mcast_data.flags |= BATADV_MCAST_WANT_ALL_IPV6;
+
+update:
+	batadv_mcast_bridge_log(bat_priv, bridged, &querier4, &querier6);
+
+	bat_priv->mcast.querier_ipv4.exists = querier4.exists;
+	bat_priv->mcast.querier_ipv4.shadowing = querier4.shadowing;
+
+	bat_priv->mcast.querier_ipv6.exists = querier6.exists;
+	bat_priv->mcast.querier_ipv6.shadowing = querier6.shadowing;
+
+	bat_priv->mcast.bridged = bridged;
 
 	if (!bat_priv->mcast.enabled ||
 	    mcast_data.flags != bat_priv->mcast.flags) {
-		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_MCAST, 1,
+		batadv_mcast_flags_log(bat_priv, mcast_data.flags);
+		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_MCAST, 2,
 					       &mcast_data, sizeof(mcast_data));
 		bat_priv->mcast.flags = mcast_data.flags;
 		bat_priv->mcast.enabled = true;
 	}
 
-	return true;
+	return !(mcast_data.flags &
+		 (BATADV_MCAST_WANT_ALL_IPV4 + BATADV_MCAST_WANT_ALL_IPV6));
 }
 
 /**
@@ -274,6 +546,10 @@ void batadv_mcast_mla_update(struct batadv_priv *bat_priv)
 	if (ret < 0)
 		goto out;
 
+	ret = batadv_mcast_mla_bridge_get(soft_iface, &mcast_list);
+	if (ret < 0)
+		goto out;
+
 update:
 	batadv_mcast_mla_tt_retract(bat_priv, &mcast_list);
 	batadv_mcast_mla_tt_add(bat_priv, &mcast_list);
@@ -283,6 +559,31 @@ out:
 }
 
 /**
+ * batadv_mcast_is_report_ipv4 - check for IGMP reports
+ * @skb: the ethernet frame destined for the mesh
+ *
+ * This call might reallocate skb data.
+ *
+ * Checks whether the given frame is a valid IGMP report.
+ *
+ * Return: If so then true, otherwise false.
+ */
+static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb)
+{
+	if (ip_mc_check_igmp(skb, NULL) < 0)
+		return false;
+
+	switch (igmp_hdr(skb)->type) {
+	case IGMP_HOST_MEMBERSHIP_REPORT:
+	case IGMPV2_HOST_MEMBERSHIP_REPORT:
+	case IGMPV3_HOST_MEMBERSHIP_REPORT:
+		return true;
+	}
+
+	return false;
+}
+
+/**
  * batadv_mcast_forw_mode_check_ipv4 - check for optimized forwarding potential
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the IPv4 packet to check
@@ -304,6 +605,9 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
 	if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*iphdr)))
 		return -ENOMEM;
 
+	if (batadv_mcast_is_report_ipv4(skb))
+		return -EINVAL;
+
 	iphdr = ip_hdr(skb);
 
 	/* TODO: Implement Multicast Router Discovery (RFC4286),
@@ -320,6 +624,31 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
 	return 0;
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+/**
+ * batadv_mcast_is_report_ipv6 - check for MLD reports
+ * @skb: the ethernet frame destined for the mesh
+ *
+ * This call might reallocate skb data.
+ *
+ * Checks whether the given frame is a valid MLD report.
+ *
+ * Return: If so then true, otherwise false.
+ */
+static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb)
+{
+	if (ipv6_mc_check_mld(skb, NULL) < 0)
+		return false;
+
+	switch (icmp6_hdr(skb)->icmp6_type) {
+	case ICMPV6_MGM_REPORT:
+	case ICMPV6_MLD2_REPORT:
+		return true;
+	}
+
+	return false;
+}
+
 /**
  * batadv_mcast_forw_mode_check_ipv6 - check for optimized forwarding potential
  * @bat_priv: the bat priv with all the soft interface information
@@ -341,6 +670,9 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 	if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*ip6hdr)))
 		return -ENOMEM;
 
+	if (batadv_mcast_is_report_ipv6(skb))
+		return -EINVAL;
+
 	ip6hdr = ipv6_hdr(skb);
 
 	/* TODO: Implement Multicast Router Discovery (RFC4286),
@@ -357,6 +689,7 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 
 	return 0;
 }
+#endif
 
 /**
  * batadv_mcast_forw_mode_check - check for optimized forwarding potential
@@ -385,9 +718,11 @@ static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
 	case ETH_P_IP:
 		return batadv_mcast_forw_mode_check_ipv4(bat_priv, skb,
 							 is_unsnoopable);
+#if IS_ENABLED(CONFIG_IPV6)
 	case ETH_P_IPV6:
 		return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb,
 							 is_unsnoopable);
+#endif
 	default:
 		return -EINVAL;
 	}
@@ -727,18 +1062,18 @@ static void batadv_mcast_want_ipv6_update(struct batadv_priv *bat_priv,
 }
 
 /**
- * batadv_mcast_tvlv_ogm_handler_v1 - process incoming multicast tvlv container
+ * batadv_mcast_tvlv_ogm_handler - process incoming multicast tvlv container
  * @bat_priv: the bat priv with all the soft interface information
  * @orig: the orig_node of the ogm
  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
  * @tvlv_value: tvlv buffer containing the multicast data
  * @tvlv_value_len: tvlv buffer length
  */
-static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
-					     struct batadv_orig_node *orig,
-					     u8 flags,
-					     void *tvlv_value,
-					     u16 tvlv_value_len)
+static void batadv_mcast_tvlv_ogm_handler(struct batadv_priv *bat_priv,
+					  struct batadv_orig_node *orig,
+					  u8 flags,
+					  void *tvlv_value,
+					  u16 tvlv_value_len)
 {
 	bool orig_mcast_enabled = !(flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
 	u8 mcast_flags = BATADV_NO_FLAGS;
@@ -788,19 +1123,118 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
  */
 void batadv_mcast_init(struct batadv_priv *bat_priv)
 {
-	batadv_tvlv_handler_register(bat_priv, batadv_mcast_tvlv_ogm_handler_v1,
-				     NULL, BATADV_TVLV_MCAST, 1,
+	batadv_tvlv_handler_register(bat_priv, batadv_mcast_tvlv_ogm_handler,
+				     NULL, BATADV_TVLV_MCAST, 2,
 				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
 }
 
 /**
+ * batadv_mcast_flags_print_header - print own mcast flags to debugfs table
+ * @bat_priv: the bat priv with all the soft interface information
+ * @seq: debugfs table seq_file struct
+ *
+ * Prints our own multicast flags including a more specific reason why
+ * they are set, that is prints the bridge and querier state too, to
+ * the debugfs table specified via @seq.
+ */
+static void batadv_mcast_flags_print_header(struct batadv_priv *bat_priv,
+					    struct seq_file *seq)
+{
+	u8 flags = bat_priv->mcast.flags;
+	char querier4, querier6, shadowing4, shadowing6;
+	bool bridged = bat_priv->mcast.bridged;
+
+	if (bridged) {
+		querier4 = bat_priv->mcast.querier_ipv4.exists ? '.' : '4';
+		querier6 = bat_priv->mcast.querier_ipv6.exists ? '.' : '6';
+		shadowing4 = bat_priv->mcast.querier_ipv4.shadowing ? '4' : '.';
+		shadowing6 = bat_priv->mcast.querier_ipv6.shadowing ? '6' : '.';
+	} else {
+		querier4 = '?';
+		querier6 = '?';
+		shadowing4 = '?';
+		shadowing6 = '?';
+	}
+
+	seq_printf(seq, "Multicast flags (own flags: [%c%c%c])\n",
+		   flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES ? 'U' : '.',
+		   flags & BATADV_MCAST_WANT_ALL_IPV4 ? '4' : '.',
+		   flags & BATADV_MCAST_WANT_ALL_IPV6 ? '6' : '.');
+	seq_printf(seq, "* Bridged [U]\t\t\t\t%c\n", bridged ? 'U' : '.');
+	seq_printf(seq, "* No IGMP/MLD Querier [4/6]:\t\t%c/%c\n",
+		   querier4, querier6);
+	seq_printf(seq, "* Shadowing IGMP/MLD Querier [4/6]:\t%c/%c\n",
+		   shadowing4, shadowing6);
+	seq_puts(seq, "-------------------------------------------\n");
+	seq_printf(seq, "       %-10s %s\n", "Originator", "Flags");
+}
+
+/**
+ * batadv_mcast_flags_seq_print_text - print the mcast flags of other nodes
+ * @seq: seq file to print on
+ * @offset: not used
+ *
+ * This prints a table of (primary) originators and their according
+ * multicast flags, including (in the header) our own.
+ */
+int batadv_mcast_flags_seq_print_text(struct seq_file *seq, void *offset)
+{
+	struct net_device *net_dev = (struct net_device *)seq->private;
+	struct batadv_priv *bat_priv = netdev_priv(net_dev);
+	struct batadv_hard_iface *primary_if;
+	struct batadv_hashtable *hash = bat_priv->orig_hash;
+	struct batadv_orig_node *orig_node;
+	struct hlist_head *head;
+	u8 flags;
+	u32 i;
+
+	primary_if = batadv_seq_print_text_primary_if_get(seq);
+	if (!primary_if)
+		return 0;
+
+	batadv_mcast_flags_print_header(bat_priv, seq);
+
+	for (i = 0; i < hash->size; i++) {
+		head = &hash->table[i];
+
+		rcu_read_lock();
+		hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
+			if (!(orig_node->capa_initialized &
+			      BATADV_ORIG_CAPA_HAS_MCAST))
+				continue;
+
+			flags = orig_node->mcast_flags;
+
+			if (!(orig_node->capabilities &
+			      BATADV_ORIG_CAPA_HAS_MCAST)) {
+				seq_printf(seq, "%pM -\n", orig_node->orig);
+				continue;
+			}
+
+			seq_printf(seq, "%pM [%c%c%c]\n", orig_node->orig,
+				   (flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES ?
+				    'U' : '.'),
+				   (flags & BATADV_MCAST_WANT_ALL_IPV4 ?
+				    '4' : '.'),
+				   (flags & BATADV_MCAST_WANT_ALL_IPV6 ?
+				    '6' : '.'));
+		}
+		rcu_read_unlock();
+	}
+
+	batadv_hardif_put(primary_if);
+
+	return 0;
+}
+
+/**
  * batadv_mcast_free - free the multicast optimizations structures
  * @bat_priv: the bat priv with all the soft interface information
  */
 void batadv_mcast_free(struct batadv_priv *bat_priv)
 {
-	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_MCAST, 1);
-	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_MCAST, 1);
+	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_MCAST, 2);
+	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_MCAST, 2);
 
 	spin_lock_bh(&bat_priv->tt.commit_lock);
 	batadv_mcast_mla_tt_retract(bat_priv, NULL);
diff --git a/net/batman-adv/multicast.h b/net/batman-adv/multicast.h
index 80bceec..df744c6 100644
--- a/net/batman-adv/multicast.h
+++ b/net/batman-adv/multicast.h
@@ -46,6 +46,8 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 
 void batadv_mcast_init(struct batadv_priv *bat_priv);
 
+int batadv_mcast_flags_seq_print_text(struct seq_file *seq, void *offset);
+
 void batadv_mcast_free(struct batadv_priv *bat_priv);
 
 void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node);
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 8a136b6..1ab46f3 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -795,6 +795,10 @@ static int batadv_softif_init_late(struct net_device *dev)
 	atomic_set(&bat_priv->distributed_arp_table, 1);
 #endif
 #ifdef CONFIG_BATMAN_ADV_MCAST
+	bat_priv->mcast.querier_ipv4.exists = false;
+	bat_priv->mcast.querier_ipv4.shadowing = false;
+	bat_priv->mcast.querier_ipv6.exists = false;
+	bat_priv->mcast.querier_ipv6.shadowing = false;
 	bat_priv->mcast.flags = BATADV_NO_FLAGS;
 	atomic_set(&bat_priv->multicast_mode, 1);
 	atomic_set(&bat_priv->mcast.num_disabled, 0);
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 1e47fbe..0ed0bee 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -745,14 +745,28 @@ struct batadv_priv_dat {
 
 #ifdef CONFIG_BATMAN_ADV_MCAST
 /**
+ * struct batadv_mcast_querier_state - IGMP/MLD querier state when bridged
+ * @exists: whether a querier exists in the mesh
+ * @shadowing: if a querier exists, whether it is potentially shadowing
+ *  multicast listeners (i.e. querier is behind our own bridge segment)
+ */
+struct batadv_mcast_querier_state {
+	bool exists;
+	bool shadowing;
+};
+
+/**
  * struct batadv_priv_mcast - per mesh interface mcast data
  * @mla_list: list of multicast addresses we are currently announcing via TT
  * @want_all_unsnoopables_list: a list of orig_nodes wanting all unsnoopable
  *  multicast traffic
  * @want_all_ipv4_list: a list of orig_nodes wanting all IPv4 multicast traffic
  * @want_all_ipv6_list: a list of orig_nodes wanting all IPv6 multicast traffic
+ * @querier_ipv4: the current state of an IGMP querier in the mesh
+ * @querier_ipv6: the current state of an MLD querier in the mesh
  * @flags: the flags we have last sent in our mcast tvlv
  * @enabled: whether the multicast tvlv is currently enabled
+ * @bridged: whether the soft interface has a bridge on top
  * @num_disabled: number of nodes that have no mcast tvlv
  * @num_want_all_unsnoopables: number of nodes wanting unsnoopable IP traffic
  * @num_want_all_ipv4: counter for items in want_all_ipv4_list
@@ -765,8 +779,11 @@ struct batadv_priv_mcast {
 	struct hlist_head want_all_unsnoopables_list;
 	struct hlist_head want_all_ipv4_list;
 	struct hlist_head want_all_ipv6_list;
+	struct batadv_mcast_querier_state querier_ipv4;
+	struct batadv_mcast_querier_state querier_ipv6;
 	u8 flags;
 	bool enabled;
+	bool bridged;
 	atomic_t num_disabled;
 	atomic_t num_want_all_unsnoopables;
 	atomic_t num_want_all_ipv4;