Merge tag 'batadv-next-pullrequest-20231115' of git://git.open-mesh.org/linux-merge

This feature/cleanup patchset includes the following patches:

 - bump version strings, by Simon Wunderlich

 - Implement new multicast packet type, including its transmission,
   forwarding and parsing, by Linus Lüssing (3 patches)

 - Switch to new headers for sprintf and array size,
   by Sven Eckelmann (2 patches)
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/batadv_packet.h

@@ -116,6 +116,9 @@ enum batadv_icmp_packettype {
  * only need routable IPv4 multicast packets we signed up for explicitly
  * @BATADV_MCAST_WANT_NO_RTR6: we have no IPv6 multicast router and therefore
  * only need routable IPv6 multicast packets we signed up for explicitly
+ * @BATADV_MCAST_HAVE_MC_PTYPE_CAPA: we can parse, receive and forward
+ * batman-adv multicast packets with a multicast tracker TVLV. And all our
+ * hard interfaces have an MTU of at least 1280 bytes.
  */
 enum batadv_mcast_flags {
 	BATADV_MCAST_WANT_ALL_UNSNOOPABLES	= 1UL << 0,
@@ -123,6 +126,7 @@ enum batadv_mcast_flags {
 	BATADV_MCAST_WANT_ALL_IPV6		= 1UL << 2,
 	BATADV_MCAST_WANT_NO_RTR4		= 1UL << 3,
 	BATADV_MCAST_WANT_NO_RTR6		= 1UL << 4,
+	BATADV_MCAST_HAVE_MC_PTYPE_CAPA		= 1UL << 5,
 };
 
 /* tt data subtypes */
@@ -174,14 +178,16 @@ enum batadv_bla_claimframe {
  * @BATADV_TVLV_TT: translation table tvlv
  * @BATADV_TVLV_ROAM: roaming advertisement tvlv
  * @BATADV_TVLV_MCAST: multicast capability tvlv
+ * @BATADV_TVLV_MCAST_TRACKER: multicast tracker tvlv
  */
 enum batadv_tvlv_type {
-	BATADV_TVLV_GW		= 0x01,
-	BATADV_TVLV_DAT		= 0x02,
-	BATADV_TVLV_NC		= 0x03,
-	BATADV_TVLV_TT		= 0x04,
-	BATADV_TVLV_ROAM	= 0x05,
-	BATADV_TVLV_MCAST	= 0x06,
+	BATADV_TVLV_GW			= 0x01,
+	BATADV_TVLV_DAT			= 0x02,
+	BATADV_TVLV_NC			= 0x03,
+	BATADV_TVLV_TT			= 0x04,
+	BATADV_TVLV_ROAM		= 0x05,
+	BATADV_TVLV_MCAST		= 0x06,
+	BATADV_TVLV_MCAST_TRACKER	= 0x07,
 };
 
 #pragma pack(2)
@@ -487,6 +493,25 @@ struct batadv_bcast_packet {
 	 */
 };
 
+/**
+ * struct batadv_mcast_packet - multicast packet for network payload
+ * @packet_type: batman-adv packet type, part of the general header
+ * @version: batman-adv protocol version, part of the general header
+ * @ttl: time to live for this packet, part of the general header
+ * @reserved: reserved byte for alignment
+ * @tvlv_len: length of the appended tvlv buffer (in bytes)
+ */
+struct batadv_mcast_packet {
+	__u8 packet_type;
+	__u8 version;
+	__u8 ttl;
+	__u8 reserved;
+	__be16 tvlv_len;
+	/* "4 bytes boundary + 2 bytes" long to make the payload after the
+	 * following ethernet header again 4 bytes boundary aligned
+	 */
+};
+
 /**
  * struct batadv_coded_packet - network coded packet
  * @packet_type: batman-adv packet type, part of the general header
@@ -628,6 +653,14 @@ struct batadv_tvlv_mcast_data {
 	__u8 reserved[3];
 };
 
+/**
+ * struct batadv_tvlv_mcast_tracker - payload of a multicast tracker tvlv
+ * @num_dests: number of subsequent destination originator MAC addresses
+ */
+struct batadv_tvlv_mcast_tracker {
+	__be16	num_dests;
+};
+
 #pragma pack()
 
 #endif /* _UAPI_LINUX_BATADV_PACKET_H_ */

net/batman-adv/Makefile

@@ -20,6 +20,7 @@ batman-adv-y += hash.o
 batman-adv-$(CONFIG_BATMAN_ADV_DEBUG) += log.o
 batman-adv-y += main.o
 batman-adv-$(CONFIG_BATMAN_ADV_MCAST) += multicast.o
+batman-adv-$(CONFIG_BATMAN_ADV_MCAST) += multicast_forw.o
 batman-adv-y += netlink.o
 batman-adv-$(CONFIG_BATMAN_ADV_NC) += network-coding.o
 batman-adv-y += originator.o

net/batman-adv/bridge_loop_avoidance.c

@@ -20,7 +20,6 @@
 #include <linux/if_vlan.h>
 #include <linux/jhash.h>
 #include <linux/jiffies.h>
-#include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/lockdep.h>
@@ -31,6 +30,7 @@
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/sprintf.h>
 #include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/workqueue.h>

net/batman-adv/fragmentation.c

@@ -25,7 +25,6 @@
 
 #include "hard-interface.h"
 #include "originator.h"
-#include "routing.h"
 #include "send.h"
 
 /**
@@ -351,18 +350,14 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb,
 			 struct batadv_orig_node *orig_node_src)
 {
 	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
-	struct batadv_orig_node *orig_node_dst;
 	struct batadv_neigh_node *neigh_node = NULL;
 	struct batadv_frag_packet *packet;
 	u16 total_size;
 	bool ret = false;
 
 	packet = (struct batadv_frag_packet *)skb->data;
-	orig_node_dst = batadv_orig_hash_find(bat_priv, packet->dest);
-	if (!orig_node_dst)
-		goto out;
 
-	neigh_node = batadv_find_router(bat_priv, orig_node_dst, recv_if);
+	neigh_node = batadv_orig_to_router(bat_priv, packet->dest, recv_if);
 	if (!neigh_node)
 		goto out;
 
@@ -381,7 +376,6 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb,
 	}
 
 out:
-	batadv_orig_node_put(orig_node_dst);
 	batadv_neigh_node_put(neigh_node);
 	return ret;
 }

net/batman-adv/gateway_client.c

@@ -18,7 +18,6 @@
 #include <linux/in.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
-#include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/list.h>
 #include <linux/lockdep.h>
@@ -29,6 +28,7 @@
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/sprintf.h>
 #include <linux/stddef.h>
 #include <linux/udp.h>
 #include <net/sock.h>

net/batman-adv/main.c

@@ -6,6 +6,7 @@
 
 #include "main.h"
 
+#include <linux/array_size.h>
 #include <linux/atomic.h>
 #include <linux/build_bug.h>
 #include <linux/byteorder/generic.h>
@@ -20,7 +21,6 @@
 #include <linux/init.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
-#include <linux/kernel.h>
 #include <linux/kobject.h>
 #include <linux/kref.h>
 #include <linux/list.h>
@@ -33,6 +33,7 @@
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/sprintf.h>
 #include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/workqueue.h>
@@ -532,6 +533,8 @@ static void batadv_recv_handler_init(void)
 
 	/* broadcast packet */
 	batadv_rx_handler[BATADV_BCAST] = batadv_recv_bcast_packet;
+	/* multicast packet */
+	batadv_rx_handler[BATADV_MCAST] = batadv_recv_mcast_packet;
 
 	/* unicast packets ... */
 	/* unicast with 4 addresses packet */

net/batman-adv/main.h

@@ -13,7 +13,7 @@
 #define BATADV_DRIVER_DEVICE "batman-adv"
 
 #ifndef BATADV_SOURCE_VERSION
-#define BATADV_SOURCE_VERSION "2023.3"
+#define BATADV_SOURCE_VERSION "2024.0"
 #endif
 
 /* B.A.T.M.A.N. parameters */

net/batman-adv/multicast.c

@@ -25,7 +25,6 @@
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/jiffies.h>
-#include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/lockdep.h>
 #include <linux/netdevice.h>
@@ -36,6 +35,7 @@
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/sprintf.h>
 #include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/types.h>
@@ -235,6 +235,37 @@ static u8 batadv_mcast_mla_rtr_flags_get(struct batadv_priv *bat_priv,
 	return flags;
 }
 
+/**
+ * batadv_mcast_mla_forw_flags_get() - get multicast forwarding flags
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Checks if all active hard interfaces have an MTU larger or equal to 1280
+ * bytes (IPv6 minimum MTU).
+ *
+ * Return: BATADV_MCAST_HAVE_MC_PTYPE_CAPA if yes, BATADV_NO_FLAGS otherwise.
+ */
+static u8 batadv_mcast_mla_forw_flags_get(struct batadv_priv *bat_priv)
+{
+	const struct batadv_hard_iface *hard_iface;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
+		if (hard_iface->if_status != BATADV_IF_ACTIVE)
+			continue;
+
+		if (hard_iface->soft_iface != bat_priv->soft_iface)
+			continue;
+
+		if (hard_iface->net_dev->mtu < IPV6_MIN_MTU) {
+			rcu_read_unlock();
+			return BATADV_NO_FLAGS;
+		}
+	}
+	rcu_read_unlock();
+
+	return BATADV_MCAST_HAVE_MC_PTYPE_CAPA;
+}
+
 /**
  * batadv_mcast_mla_flags_get() - get the new multicast flags
  * @bat_priv: the bat priv with all the soft interface information
@@ -256,6 +287,7 @@ batadv_mcast_mla_flags_get(struct batadv_priv *bat_priv)
 	mla_flags.enabled = 1;
 	mla_flags.tvlv_flags |= batadv_mcast_mla_rtr_flags_get(bat_priv,
 							       bridge);
+	mla_flags.tvlv_flags |= batadv_mcast_mla_forw_flags_get(bat_priv);
 
 	if (!bridge)
 		return mla_flags;
@@ -806,23 +838,25 @@ static void batadv_mcast_flags_log(struct batadv_priv *bat_priv, u8 flags)
 {
 	bool old_enabled = bat_priv->mcast.mla_flags.enabled;
 	u8 old_flags = bat_priv->mcast.mla_flags.tvlv_flags;
-	char str_old_flags[] = "[.... . ]";
+	char str_old_flags[] = "[.... . .]";
 
-	sprintf(str_old_flags, "[%c%c%c%s%s]",
+	sprintf(str_old_flags, "[%c%c%c%s%s%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' : '.',
 		!(old_flags & BATADV_MCAST_WANT_NO_RTR4) ? "R4" : ". ",
-		!(old_flags & BATADV_MCAST_WANT_NO_RTR6) ? "R6" : ". ");
+		!(old_flags & BATADV_MCAST_WANT_NO_RTR6) ? "R6" : ". ",
+		!(old_flags & BATADV_MCAST_HAVE_MC_PTYPE_CAPA) ? 'P' : '.');
 
 	batadv_dbg(BATADV_DBG_MCAST, bat_priv,
-		   "Changing multicast flags from '%s' to '[%c%c%c%s%s]'\n",
+		   "Changing multicast flags from '%s' to '[%c%c%c%s%s%c]'\n",
 		   old_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' : '.',
 		   !(flags & BATADV_MCAST_WANT_NO_RTR4) ? "R4" : ". ",
-		   !(flags & BATADV_MCAST_WANT_NO_RTR6) ? "R6" : ". ");
+		   !(flags & BATADV_MCAST_WANT_NO_RTR6) ? "R6" : ". ",
+		   !(flags & BATADV_MCAST_HAVE_MC_PTYPE_CAPA) ? 'P' : '.');
 }
 
 /**
@@ -1135,17 +1169,62 @@ static int batadv_mcast_forw_rtr_count(struct batadv_priv *bat_priv,
 	}
 }
 
+/**
+ * batadv_mcast_forw_mode_by_count() - get forwarding mode by count
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to check
+ * @vid: the vlan identifier
+ * @is_routable: stores whether the destination is routable
+ * @count: the number of originators the multicast packet need to be sent to
+ *
+ * For a multicast packet with multiple destination originators, checks which
+ * mode to use. For BATADV_FORW_MCAST it also encapsulates the packet with a
+ * complete batman-adv multicast header.
+ *
+ * Return:
+ *	BATADV_FORW_MCAST: If all nodes have multicast packet routing
+ *	capabilities and an MTU >= 1280 on all hard interfaces (including us)
+ *	and the encapsulated multicast packet with all destination addresses
+ *	would still fit into an 1280 bytes batman-adv multicast packet
+ *	(excluding the outer ethernet frame) and we could successfully push
+ *	the full batman-adv multicast packet header.
+ *	BATADV_FORW_UCASTS: If the packet cannot be sent in a batman-adv
+ *	multicast packet and the amount of batman-adv unicast packets needed
+ *	is smaller or equal to the configured multicast fanout.
+ *	BATADV_FORW_BCAST: Otherwise.
+ */
+static enum batadv_forw_mode
+batadv_mcast_forw_mode_by_count(struct batadv_priv *bat_priv,
+				struct sk_buff *skb, unsigned short vid,
+				int is_routable, int count)
+{
+	unsigned int mcast_hdrlen = batadv_mcast_forw_packet_hdrlen(count);
+	u8 own_tvlv_flags = bat_priv->mcast.mla_flags.tvlv_flags;
+
+	if (!atomic_read(&bat_priv->mcast.num_no_mc_ptype_capa) &&
+	    own_tvlv_flags & BATADV_MCAST_HAVE_MC_PTYPE_CAPA &&
+	    skb->len + mcast_hdrlen <= IPV6_MIN_MTU &&
+	    batadv_mcast_forw_push(bat_priv, skb, vid, is_routable, count))
+		return BATADV_FORW_MCAST;
+
+	if (count <= atomic_read(&bat_priv->multicast_fanout))
+		return BATADV_FORW_UCASTS;
+
+	return BATADV_FORW_BCAST;
+}
+
 /**
  * batadv_mcast_forw_mode() - check on how to forward a multicast packet
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the multicast packet to check
+ * @vid: the vlan identifier
  * @is_routable: stores whether the destination is routable
  *
  * Return: The forwarding mode as enum batadv_forw_mode.
  */
 enum batadv_forw_mode
 batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
-		       int *is_routable)
+		       unsigned short vid, int *is_routable)
 {
 	int ret, tt_count, ip_count, unsnoop_count, total_count;
 	bool is_unsnoopable = false;
@@ -1175,10 +1254,8 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 	else if (unsnoop_count)
 		return BATADV_FORW_BCAST;
 
-	if (total_count <= atomic_read(&bat_priv->multicast_fanout))
-		return BATADV_FORW_UCASTS;
-
-	return BATADV_FORW_BCAST;
+	return batadv_mcast_forw_mode_by_count(bat_priv, skb, vid, *is_routable,
+					       total_count);
 }
 
 /**
@@ -1738,6 +1815,31 @@ static void batadv_mcast_want_rtr6_update(struct batadv_priv *bat_priv,
 	}
 }
 
+/**
+ * batadv_mcast_have_mc_ptype_update() - update multicast packet type counter
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig: the orig_node which multicast state might have changed of
+ * @mcast_flags: flags indicating the new multicast state
+ *
+ * If the BATADV_MCAST_HAVE_MC_PTYPE_CAPA flag of this originator, orig, has
+ * toggled then this method updates the counter accordingly.
+ */
+static void batadv_mcast_have_mc_ptype_update(struct batadv_priv *bat_priv,
+					      struct batadv_orig_node *orig,
+					      u8 mcast_flags)
+{
+	lockdep_assert_held(&orig->mcast_handler_lock);
+
+	/* switched from flag set to unset */
+	if (!(mcast_flags & BATADV_MCAST_HAVE_MC_PTYPE_CAPA) &&
+	    orig->mcast_flags & BATADV_MCAST_HAVE_MC_PTYPE_CAPA)
+		atomic_inc(&bat_priv->mcast.num_no_mc_ptype_capa);
+	/* switched from flag unset to set */
+	else if (mcast_flags & BATADV_MCAST_HAVE_MC_PTYPE_CAPA &&
+		 !(orig->mcast_flags & BATADV_MCAST_HAVE_MC_PTYPE_CAPA))
+		atomic_dec(&bat_priv->mcast.num_no_mc_ptype_capa);
+}
+
 /**
  * batadv_mcast_tvlv_flags_get() - get multicast flags from an OGM TVLV
  * @enabled: whether the originator has multicast TVLV support enabled
@@ -1806,6 +1908,7 @@ static void batadv_mcast_tvlv_ogm_handler(struct batadv_priv *bat_priv,
 	batadv_mcast_want_ipv6_update(bat_priv, orig, mcast_flags);
 	batadv_mcast_want_rtr4_update(bat_priv, orig, mcast_flags);
 	batadv_mcast_want_rtr6_update(bat_priv, orig, mcast_flags);
+	batadv_mcast_have_mc_ptype_update(bat_priv, orig, mcast_flags);
 
 	orig->mcast_flags = mcast_flags;
 	spin_unlock_bh(&orig->mcast_handler_lock);
@@ -1820,6 +1923,10 @@ void batadv_mcast_init(struct batadv_priv *bat_priv)
 	batadv_tvlv_handler_register(bat_priv, batadv_mcast_tvlv_ogm_handler,
 				     NULL, NULL, BATADV_TVLV_MCAST, 2,
 				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
+	batadv_tvlv_handler_register(bat_priv, NULL, NULL,
+				     batadv_mcast_forw_tracker_tvlv_handler,
+				     BATADV_TVLV_MCAST_TRACKER, 1,
+				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
 
 	INIT_DELAYED_WORK(&bat_priv->mcast.work, batadv_mcast_mla_update);
 	batadv_mcast_start_timer(bat_priv);

net/batman-adv/multicast.h

@@ -11,6 +11,7 @@
 
 #include <linux/netlink.h>
 #include <linux/skbuff.h>
+#include <linux/types.h>
 
 /**
  * enum batadv_forw_mode - the way a packet should be forwarded as
@@ -28,6 +29,12 @@ enum batadv_forw_mode {
 	 */
 	BATADV_FORW_UCASTS,
 
+	/**
+	 * @BATADV_FORW_MCAST: forward the packet to some nodes via a
+	 *  batman-adv multicast packet
+	 */
+	BATADV_FORW_MCAST,
+
 	/** @BATADV_FORW_NONE: don't forward, drop it */
 	BATADV_FORW_NONE,
 };
@@ -36,7 +43,7 @@ enum batadv_forw_mode {
 
 enum batadv_forw_mode
 batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
-		       int *is_routable);
+		       unsigned short vid, int *is_routable);
 
 int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
 			   unsigned short vid, int is_routable);
@@ -52,11 +59,23 @@ void batadv_mcast_free(struct batadv_priv *bat_priv);
 
 void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node);
 
+/* multicast_forw.c */
+
+int batadv_mcast_forw_tracker_tvlv_handler(struct batadv_priv *bat_priv,
+					   struct sk_buff *skb);
+
+unsigned int batadv_mcast_forw_packet_hdrlen(unsigned int num_dests);
+
+bool batadv_mcast_forw_push(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			    unsigned short vid, int is_routable, int count);
+
+int batadv_mcast_forw_mcsend(struct batadv_priv *bat_priv, struct sk_buff *skb);
+
 #else
 
 static inline enum batadv_forw_mode
 batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
-		       int *is_routable)
+		       unsigned short vid, int *is_routable)
 {
 	return BATADV_FORW_BCAST;
 }
@@ -94,6 +113,13 @@ static inline void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node)
 {
 }
 
+static inline int batadv_mcast_forw_mcsend(struct batadv_priv *bat_priv,
+					   struct sk_buff *skb)
+{
+	kfree_skb(skb);
+	return NET_XMIT_DROP;
+}
+
 #endif /* CONFIG_BATMAN_ADV_MCAST */
 
 #endif /* _NET_BATMAN_ADV_MULTICAST_H_ */

net/batman-adv/multicast_forw.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) B.A.T.M.A.N. contributors:
+ *
+ * Linus Lüssing
+ */
+
+#include "multicast.h"
+#include "main.h"
+
+#include <linux/bug.h>
+#include <linux/build_bug.h>
+#include <linux/byteorder/generic.h>
+#include <linux/compiler.h>
+#include <linux/errno.h>
+#include <linux/etherdevice.h>
+#include <linux/gfp.h>
+#include <linux/if_ether.h>
+#include <linux/if_vlan.h>
+#include <linux/ipv6.h>
+#include <linux/limits.h>
+#include <linux/netdevice.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/skbuff.h>
+#include <linux/stddef.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <uapi/linux/batadv_packet.h>
+
+#include "bridge_loop_avoidance.h"
+#include "originator.h"
+#include "send.h"
+#include "translation-table.h"
+
+#define batadv_mcast_forw_tracker_for_each_dest(dest, num_dests) \
+	for (; num_dests; num_dests--, (dest) += ETH_ALEN)
+
+#define batadv_mcast_forw_tracker_for_each_dest2(dest1, dest2, num_dests) \
+	for (; num_dests; num_dests--, (dest1) += ETH_ALEN, (dest2) += ETH_ALEN)
+
+/**
+ * batadv_mcast_forw_skb_push() - skb_push and memorize amount of pushed bytes
+ * @skb: the skb to push onto
+ * @size: the amount of bytes to push
+ * @len: stores the total amount of bytes pushed
+ *
+ * Performs an skb_push() onto the given skb and adds the amount of pushed bytes
+ * to the given len pointer.
+ *
+ * Return: the return value of the skb_push() call.
+ */
+static void *batadv_mcast_forw_skb_push(struct sk_buff *skb, size_t size,
+					unsigned short *len)
+{
+	*len += size;
+	return skb_push(skb, size);
+}
+
+/**
+ * batadv_mcast_forw_push_padding() - push 2 padding bytes to skb's front
+ * @skb: the skb to push onto
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Pushes two padding bytes to the front of the given skb.
+ *
+ * Return: On success a pointer to the first byte of the two pushed padding
+ * bytes within the skb. NULL otherwise.
+ */
+static char *
+batadv_mcast_forw_push_padding(struct sk_buff *skb, unsigned short *tvlv_len)
+{
+	const int pad_len = 2;
+	char *padding;
+
+	if (skb_headroom(skb) < pad_len)
+		return NULL;
+
+	padding = batadv_mcast_forw_skb_push(skb, pad_len, tvlv_len);
+	memset(padding, 0, pad_len);
+
+	return padding;
+}
+
+/**
+ * batadv_mcast_forw_push_est_padding() - push padding bytes if necessary
+ * @skb: the skb to potentially push the padding onto
+ * @count: the (estimated) number of originators the multicast packet needs to
+ *  be sent to
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * If the number of destination entries is even then this adds two
+ * padding bytes to the end of the tracker TVLV.
+ *
+ * Return: true on success or if no padding is needed, false otherwise.
+ */
+static bool
+batadv_mcast_forw_push_est_padding(struct sk_buff *skb, int count,
+				   unsigned short *tvlv_len)
+{
+	if (!(count % 2) && !batadv_mcast_forw_push_padding(skb, tvlv_len))
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_orig_entry() - get orig_node from an hlist node
+ * @node: the hlist node to get the orig_node from
+ * @entry_offset: the offset of the hlist node within the orig_node struct
+ *
+ * Return: The orig_node containing the hlist node on success, NULL on error.
+ */
+static struct batadv_orig_node *
+batadv_mcast_forw_orig_entry(struct hlist_node *node,
+			     size_t entry_offset)
+{
+	/* sanity check */
+	switch (entry_offset) {
+	case offsetof(struct batadv_orig_node, mcast_want_all_ipv4_node):
+	case offsetof(struct batadv_orig_node, mcast_want_all_ipv6_node):
+	case offsetof(struct batadv_orig_node, mcast_want_all_rtr4_node):
+	case offsetof(struct batadv_orig_node, mcast_want_all_rtr6_node):
+		break;
+	default:
+		WARN_ON(1);
+		return NULL;
+	}
+
+	return (struct batadv_orig_node *)((void *)node - entry_offset);
+}
+
+/**
+ * batadv_mcast_forw_push_dest() - push an originator MAC address onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination address onto
+ * @vid: the vlan identifier
+ * @orig_node: the originator node to get the MAC address from
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * If the orig_node is a BLA backbone gateway, if there is not enough skb
+ * headroom available or if num_dests is already at its maximum (65535) then
+ * neither the skb nor num_dests is changed. Otherwise the originator's MAC
+ * address is pushed onto the given skb and num_dests incremented by one.
+ *
+ * Return: true if the orig_node is a backbone gateway or if an orig address
+ *  was pushed successfully, false otherwise.
+ */
+static bool batadv_mcast_forw_push_dest(struct batadv_priv *bat_priv,
+					struct sk_buff *skb, unsigned short vid,
+					struct batadv_orig_node *orig_node,
+					unsigned short *num_dests,
+					unsigned short *tvlv_len)
+{
+	BUILD_BUG_ON(sizeof_field(struct batadv_tvlv_mcast_tracker, num_dests)
+		     != sizeof(__be16));
+
+	/* Avoid sending to other BLA gateways - they already got the frame from
+	 * the LAN side we share with them.
+	 * TODO: Refactor to take BLA into account earlier in mode check.
+	 */
+	if (batadv_bla_is_backbone_gw_orig(bat_priv, orig_node->orig, vid))
+		return true;
+
+	if (skb_headroom(skb) < ETH_ALEN || *num_dests == U16_MAX)
+		return false;
+
+	batadv_mcast_forw_skb_push(skb, ETH_ALEN, tvlv_len);
+	ether_addr_copy(skb->data, orig_node->orig);
+	(*num_dests)++;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_dests_list() - push originators from list onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @head: the list to gather originators from
+ * @entry_offset: offset of an hlist node in an orig_node structure
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators in the given list onto the given
+ * skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static int batadv_mcast_forw_push_dests_list(struct batadv_priv *bat_priv,
+					     struct sk_buff *skb,
+					     unsigned short vid,
+					     struct hlist_head *head,
+					     size_t entry_offset,
+					     unsigned short *num_dests,
+					     unsigned short *tvlv_len)
+{
+	struct hlist_node *node;
+	struct batadv_orig_node *orig_node;
+
+	rcu_read_lock();
+	__hlist_for_each_rcu(node, head) {
+		orig_node = batadv_mcast_forw_orig_entry(node, entry_offset);
+		if (!orig_node ||
+		    !batadv_mcast_forw_push_dest(bat_priv, skb, vid, orig_node,
+						 num_dests, tvlv_len)) {
+			rcu_read_unlock();
+			return false;
+		}
+	}
+	rcu_read_unlock();
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_tt() - push originators with interest through TT
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet through the translation table onto the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool
+batadv_mcast_forw_push_tt(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			  unsigned short vid, unsigned short *num_dests,
+			  unsigned short *tvlv_len)
+{
+	struct batadv_tt_orig_list_entry *orig_entry;
+
+	struct batadv_tt_global_entry *tt_global;
+	const u8 *addr = eth_hdr(skb)->h_dest;
+
+	/* ok */
+	int ret = true;
+
+	tt_global = batadv_tt_global_hash_find(bat_priv, addr, vid);
+	if (!tt_global)
+		goto out;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(orig_entry, &tt_global->orig_list, list) {
+		if (!batadv_mcast_forw_push_dest(bat_priv, skb, vid,
+						 orig_entry->orig_node,
+						 num_dests, tvlv_len)) {
+			ret = false;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	batadv_tt_global_entry_put(tt_global);
+
+out:
+	return ret;
+}
+
+/**
+ * batadv_mcast_forw_push_want_all() - push originators with want-all flag
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet through the want-all flag onto the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool batadv_mcast_forw_push_want_all(struct batadv_priv *bat_priv,
+					    struct sk_buff *skb,
+					    unsigned short vid,
+					    unsigned short *num_dests,
+					    unsigned short *tvlv_len)
+{
+	struct hlist_head *head = NULL;
+	size_t offset;
+	int ret;
+
+	switch (eth_hdr(skb)->h_proto) {
+	case htons(ETH_P_IP):
+		head = &bat_priv->mcast.want_all_ipv4_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_ipv4_node);
+		break;
+	case htons(ETH_P_IPV6):
+		head = &bat_priv->mcast.want_all_ipv6_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_ipv6_node);
+		break;
+	default:
+		return false;
+	}
+
+	ret = batadv_mcast_forw_push_dests_list(bat_priv, skb, vid, head,
+						offset, num_dests, tvlv_len);
+	if (!ret)
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_want_rtr() - push originators with want-router flag
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @num_dests: a pointer to store the number of pushed addresses in
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet through the want-all-rtr flag onto the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool batadv_mcast_forw_push_want_rtr(struct batadv_priv *bat_priv,
+					    struct sk_buff *skb,
+					    unsigned short vid,
+					    unsigned short *num_dests,
+					    unsigned short *tvlv_len)
+{
+	struct hlist_head *head = NULL;
+	size_t offset;
+	int ret;
+
+	switch (eth_hdr(skb)->h_proto) {
+	case htons(ETH_P_IP):
+		head = &bat_priv->mcast.want_all_rtr4_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_rtr4_node);
+		break;
+	case htons(ETH_P_IPV6):
+		head = &bat_priv->mcast.want_all_rtr6_list;
+		offset = offsetof(struct batadv_orig_node,
+				  mcast_want_all_rtr6_node);
+		break;
+	default:
+		return false;
+	}
+
+	ret = batadv_mcast_forw_push_dests_list(bat_priv, skb, vid, head,
+						offset, num_dests, tvlv_len);
+	if (!ret)
+		return false;
+
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_scrape() - remove bytes within skb data
+ * @skb: the skb to remove bytes from
+ * @offset: the offset from the skb data from which to scrape
+ * @len: the amount of bytes to scrape starting from the offset
+ *
+ * Scrapes/removes len bytes from the given skb at the given offset from the
+ * skb data.
+ *
+ * Caller needs to ensure that the region from the skb data's start up
+ * to/including the to be removed bytes are linearized.
+ */
+static void batadv_mcast_forw_scrape(struct sk_buff *skb,
+				     unsigned short offset,
+				     unsigned short len)
+{
+	char *to, *from;
+
+	SKB_LINEAR_ASSERT(skb);
+
+	to = skb_pull(skb, len);
+	from = to - len;
+
+	memmove(to, from, offset);
+}
+
+/**
+ * batadv_mcast_forw_push_scrape_padding() - remove TVLV padding
+ * @skb: the skb to potentially adjust the TVLV's padding on
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Remove two padding bytes from the end of the multicast tracker TVLV,
+ * from before the payload data.
+ *
+ * Caller needs to ensure that the TVLV bytes are linearized.
+ */
+static void batadv_mcast_forw_push_scrape_padding(struct sk_buff *skb,
+						  unsigned short *tvlv_len)
+{
+	const int pad_len = 2;
+
+	batadv_mcast_forw_scrape(skb, *tvlv_len - pad_len, pad_len);
+	*tvlv_len -= pad_len;
+}
+
+/**
+ * batadv_mcast_forw_push_insert_padding() - insert TVLV padding
+ * @skb: the skb to potentially adjust the TVLV's padding on
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Inserts two padding bytes at the end of the multicast tracker TVLV,
+ * before the payload data in the given skb.
+ *
+ * Return: true on success, false otherwise.
+ */
+static bool batadv_mcast_forw_push_insert_padding(struct sk_buff *skb,
+						  unsigned short *tvlv_len)
+{
+	unsigned short offset =	*tvlv_len;
+	char *to, *from = skb->data;
+
+	to = batadv_mcast_forw_push_padding(skb, tvlv_len);
+	if (!to)
+		return false;
+
+	memmove(to, from, offset);
+	memset(to + offset, 0, *tvlv_len - offset);
+	return true;
+}
+
+/**
+ * batadv_mcast_forw_push_adjust_padding() - adjust padding if necessary
+ * @skb: the skb to potentially adjust the TVLV's padding on
+ * @count: the estimated number of originators the multicast packet needs to
+ *  be sent to
+ * @num_dests_pushed: the number of originators that were actually added to the
+ *  multicast packet's tracker TVLV
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Adjusts the padding in the multicast packet's tracker TVLV depending on the
+ * initially estimated amount of destinations versus the amount of destinations
+ * that were actually added to the tracker TVLV.
+ *
+ * If the initial estimate was correct or at least the oddness was the same then
+ * no padding adjustment is performed.
+ * If the initially estimated number was even, so padding was initially added,
+ * but it turned out to be odd then padding is removed.
+ * If the initially estimated number was odd, so no padding was initially added,
+ * but it turned out to be even then padding is added.
+ *
+ * Return: true if no padding adjustment is needed or the adjustment was
+ * successful, false otherwise.
+ */
+static bool
+batadv_mcast_forw_push_adjust_padding(struct sk_buff *skb, int *count,
+				      unsigned short num_dests_pushed,
+				      unsigned short *tvlv_len)
+{
+	int ret = true;
+
+	if (likely((num_dests_pushed % 2) == (*count % 2)))
+		goto out;
+
+	/**
+	 * estimated even number of destinations, but turned out to be odd
+	 * -> remove padding
+	 */
+	if (!(*count % 2) && (num_dests_pushed % 2))
+		batadv_mcast_forw_push_scrape_padding(skb, tvlv_len);
+	/**
+	 * estimated odd number of destinations, but turned out to be even
+	 * -> add padding
+	 */
+	else if ((*count % 2) && (!(num_dests_pushed % 2)))
+		ret = batadv_mcast_forw_push_insert_padding(skb, tvlv_len);
+
+out:
+	*count = num_dests_pushed;
+	return ret;
+}
+
+/**
+ * batadv_mcast_forw_push_dests() - push originator addresses onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the destination addresses onto
+ * @vid: the vlan identifier
+ * @is_routable: indicates whether the destination is routable
+ * @count: the number of originators the multicast packet needs to be sent to
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Push the MAC addresses of all originators which have indicated interest in
+ * this multicast packet onto the given skb.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int
+batadv_mcast_forw_push_dests(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			     unsigned short vid, int is_routable, int *count,
+			     unsigned short *tvlv_len)
+{
+	unsigned short num_dests = 0;
+
+	if (!batadv_mcast_forw_push_est_padding(skb, *count, tvlv_len))
+		goto err;
+
+	if (!batadv_mcast_forw_push_tt(bat_priv, skb, vid, &num_dests,
+				       tvlv_len))
+		goto err;
+
+	if (!batadv_mcast_forw_push_want_all(bat_priv, skb, vid, &num_dests,
+					     tvlv_len))
+		goto err;
+
+	if (is_routable &&
+	    !batadv_mcast_forw_push_want_rtr(bat_priv, skb, vid, &num_dests,
+					     tvlv_len))
+		goto err;
+
+	if (!batadv_mcast_forw_push_adjust_padding(skb, count, num_dests,
+						   tvlv_len))
+		goto err;
+
+	return 0;
+err:
+	return -ENOMEM;
+}
+
+/**
+ * batadv_mcast_forw_push_tracker() - push a multicast tracker TVLV header
+ * @skb: the skb to push the tracker TVLV onto
+ * @num_dests: the number of destination addresses to set in the header
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Pushes a multicast tracker TVLV header onto the given skb, including the
+ * generic TVLV header but excluding the destination MAC addresses.
+ *
+ * The provided num_dests value is taken into consideration to set the
+ * num_dests field in the tracker header and to set the appropriate TVLV length
+ * value fields.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int batadv_mcast_forw_push_tracker(struct sk_buff *skb, int num_dests,
+					  unsigned short *tvlv_len)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	struct batadv_tvlv_hdr *tvlv_hdr;
+	unsigned int tvlv_value_len;
+
+	if (skb_headroom(skb) < sizeof(*mcast_tracker) + sizeof(*tvlv_hdr))
+		return -ENOMEM;
+
+	tvlv_value_len = sizeof(*mcast_tracker) + *tvlv_len;
+	if (tvlv_value_len + sizeof(*tvlv_hdr) > U16_MAX)
+		return -ENOMEM;
+
+	batadv_mcast_forw_skb_push(skb, sizeof(*mcast_tracker), tvlv_len);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb->data;
+	mcast_tracker->num_dests = htons(num_dests);
+
+	skb_reset_network_header(skb);
+
+	batadv_mcast_forw_skb_push(skb, sizeof(*tvlv_hdr), tvlv_len);
+	tvlv_hdr = (struct batadv_tvlv_hdr *)skb->data;
+	tvlv_hdr->type = BATADV_TVLV_MCAST_TRACKER;
+	tvlv_hdr->version = 1;
+	tvlv_hdr->len = htons(tvlv_value_len);
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_push_tvlvs() - push a multicast tracker TVLV onto an skb
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the skb to push the tracker TVLV onto
+ * @vid: the vlan identifier
+ * @is_routable: indicates whether the destination is routable
+ * @count: the number of originators the multicast packet needs to be sent to
+ * @tvlv_len: stores the amount of currently pushed TVLV bytes
+ *
+ * Pushes a multicast tracker TVLV onto the given skb, including the collected
+ * destination MAC addresses and the generic TVLV header.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int
+batadv_mcast_forw_push_tvlvs(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			     unsigned short vid, int is_routable, int count,
+			     unsigned short *tvlv_len)
+{
+	int ret;
+
+	ret = batadv_mcast_forw_push_dests(bat_priv, skb, vid, is_routable,
+					   &count, tvlv_len);
+	if (ret < 0)
+		return ret;
+
+	ret = batadv_mcast_forw_push_tracker(skb, count, tvlv_len);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_push_hdr() - push a multicast packet header onto an skb
+ * @skb: the skb to push the header onto
+ * @tvlv_len: the total TVLV length value to set in the header
+ *
+ * Pushes a batman-adv multicast packet header onto the given skb and sets
+ * the provided total TVLV length value in it.
+ *
+ * Caller needs to ensure enough skb headroom is available.
+ *
+ * Return: -ENOMEM if there is not enough skb headroom available. Otherwise, on
+ * success 0.
+ */
+static int
+batadv_mcast_forw_push_hdr(struct sk_buff *skb, unsigned short tvlv_len)
+{
+	struct batadv_mcast_packet *mcast_packet;
+
+	if (skb_headroom(skb) < sizeof(*mcast_packet))
+		return -ENOMEM;
+
+	skb_push(skb, sizeof(*mcast_packet));
+
+	mcast_packet = (struct batadv_mcast_packet *)skb->data;
+	mcast_packet->version = BATADV_COMPAT_VERSION;
+	mcast_packet->ttl = BATADV_TTL;
+	mcast_packet->packet_type = BATADV_MCAST;
+	mcast_packet->reserved = 0;
+	mcast_packet->tvlv_len = htons(tvlv_len);
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_scrub_dests() - scrub destinations in a tracker TVLV
+ * @bat_priv: the bat priv with all the soft interface information
+ * @comp_neigh: next hop neighbor to scrub+collect destinations for
+ * @dest: start MAC entry in original skb's tracker TVLV
+ * @next_dest: start MAC entry in to be sent skb's tracker TVLV
+ * @num_dests: number of remaining destination MAC entries to iterate over
+ *
+ * This sorts destination entries into either the original batman-adv
+ * multicast packet or the skb (copy) that is going to be sent to comp_neigh
+ * next.
+ *
+ * In preparation for the next, to be (unicast) transmitted batman-adv multicast
+ * packet skb to be sent to the given neighbor node, tries to collect all
+ * originator MAC addresses that have the given neighbor node as their next hop
+ * in the to be transmitted skb (copy), which next_dest points into. That is we
+ * zero all destination entries in next_dest which do not have comp_neigh as
+ * their next hop. And zero all destination entries in the original skb that
+ * would have comp_neigh as their next hop (to avoid redundant transmissions and
+ * duplicated payload later).
+ */
+static void
+batadv_mcast_forw_scrub_dests(struct batadv_priv *bat_priv,
+			      struct batadv_neigh_node *comp_neigh, u8 *dest,
+			      u8 *next_dest, u16 num_dests)
+{
+	struct batadv_neigh_node *next_neigh;
+
+	/* skip first entry, this is what we are comparing with */
+	eth_zero_addr(dest);
+	dest += ETH_ALEN;
+	next_dest += ETH_ALEN;
+	num_dests--;
+
+	batadv_mcast_forw_tracker_for_each_dest2(dest, next_dest, num_dests) {
+		if (is_zero_ether_addr(next_dest))
+			continue;
+
+		/* sanity check, we expect unicast destinations */
+		if (is_multicast_ether_addr(next_dest)) {
+			eth_zero_addr(dest);
+			eth_zero_addr(next_dest);
+			continue;
+		}
+
+		next_neigh = batadv_orig_to_router(bat_priv, next_dest, NULL);
+		if (!next_neigh) {
+			eth_zero_addr(next_dest);
+			continue;
+		}
+
+		if (!batadv_compare_eth(next_neigh->addr, comp_neigh->addr)) {
+			eth_zero_addr(next_dest);
+			batadv_neigh_node_put(next_neigh);
+			continue;
+		}
+
+		/* found an entry for our next packet to transmit, so remove it
+		 * from the original packet
+		 */
+		eth_zero_addr(dest);
+		batadv_neigh_node_put(next_neigh);
+	}
+}
+
+/**
+ * batadv_mcast_forw_shrink_fill() - swap slot with next non-zero destination
+ * @slot: the to be filled zero-MAC destination entry in a tracker TVLV
+ * @num_dests_slot: remaining entries in tracker TVLV from/including slot
+ *
+ * Searches for the next non-zero-MAC destination entry in a tracker TVLV after
+ * the given slot pointer. And if found, swaps it with the zero-MAC destination
+ * entry which the slot points to.
+ *
+ * Return: true if slot was swapped/filled successfully, false otherwise.
+ */
+static bool batadv_mcast_forw_shrink_fill(u8 *slot, u16 num_dests_slot)
+{
+	u16 num_dests_filler;
+	u8 *filler;
+
+	/* sanity check, should not happen */
+	if (!num_dests_slot)
+		return false;
+
+	num_dests_filler = num_dests_slot - 1;
+	filler = slot + ETH_ALEN;
+
+	/* find a candidate to fill the empty slot */
+	batadv_mcast_forw_tracker_for_each_dest(filler, num_dests_filler) {
+		if (is_zero_ether_addr(filler))
+			continue;
+
+		ether_addr_copy(slot, filler);
+		eth_zero_addr(filler);
+		return true;
+	}
+
+	return false;
+}
+
+/**
+ * batadv_mcast_forw_shrink_pack_dests() - pack destinations of a tracker TVLV
+ * @skb: the batman-adv multicast packet to compact destinations in
+ *
+ * Compacts the originator destination MAC addresses in the multicast tracker
+ * TVLV of the given multicast packet. This is done by moving all non-zero
+ * MAC addresses in direction of the skb head and all zero MAC addresses in skb
+ * tail direction, within the multicast tracker TVLV.
+ *
+ * Return: The number of consecutive zero MAC address destinations which are
+ * now at the end of the multicast tracker TVLV.
+ */
+static int batadv_mcast_forw_shrink_pack_dests(struct sk_buff *skb)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	unsigned char *skb_net_hdr;
+	u16 num_dests_slot;
+	u8 *slot;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests_slot = ntohs(mcast_tracker->num_dests);
+
+	slot = (u8 *)mcast_tracker + sizeof(*mcast_tracker);
+
+	batadv_mcast_forw_tracker_for_each_dest(slot, num_dests_slot) {
+		/* find an empty slot */
+		if (!is_zero_ether_addr(slot))
+			continue;
+
+		if (!batadv_mcast_forw_shrink_fill(slot, num_dests_slot))
+			/* could not find a filler, so we successfully packed
+			 * and can stop - and must not reduce num_dests_slot!
+			 */
+			break;
+	}
+
+	/* num_dests_slot is now the amount of reduced, zeroed
+	 * destinations at the end of the tracker TVLV
+	 */
+	return num_dests_slot;
+}
+
+/**
+ * batadv_mcast_forw_shrink_align_offset() - get new alignment offset
+ * @num_dests_old: the old, to be updated amount of destination nodes
+ * @num_dests_reduce: the number of destinations that were removed
+ *
+ * Calculates the amount of potential extra alignment offset that is needed to
+ * adjust the TVLV padding after the change in destination nodes.
+ *
+ * Return:
+ *	0: If no change to padding is needed.
+ *	2: If padding needs to be removed.
+ *	-2: If padding needs to be added.
+ */
+static short
+batadv_mcast_forw_shrink_align_offset(unsigned int num_dests_old,
+				      unsigned int num_dests_reduce)
+{
+	/* even amount of removed destinations -> no alignment change */
+	if (!(num_dests_reduce % 2))
+		return 0;
+
+	/* even to odd amount of destinations -> remove padding */
+	if (!(num_dests_old % 2))
+		return 2;
+
+	/* odd to even amount of destinations -> add padding */
+	return -2;
+}
+
+/**
+ * batadv_mcast_forw_shrink_update_headers() - update shrunk mc packet headers
+ * @skb: the batman-adv multicast packet to update headers of
+ * @num_dests_reduce: the number of destinations that were removed
+ *
+ * This updates any fields of a batman-adv multicast packet that are affected
+ * by the reduced number of destinations in the multicast tracket TVLV. In
+ * particular this updates:
+ *
+ * The num_dest field of the multicast tracker TVLV.
+ * The TVLV length field of the according generic TVLV header.
+ * The batman-adv multicast packet's total TVLV length field.
+ *
+ * Return: The offset in skb's tail direction at which the new batman-adv
+ * multicast packet header needs to start.
+ */
+static unsigned int
+batadv_mcast_forw_shrink_update_headers(struct sk_buff *skb,
+					unsigned int num_dests_reduce)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	struct batadv_mcast_packet *mcast_packet;
+	struct batadv_tvlv_hdr *tvlv_hdr;
+	unsigned char *skb_net_hdr;
+	unsigned int offset;
+	short align_offset;
+	u16 num_dests;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests = ntohs(mcast_tracker->num_dests);
+
+	align_offset = batadv_mcast_forw_shrink_align_offset(num_dests,
+							     num_dests_reduce);
+	offset = ETH_ALEN * num_dests_reduce + align_offset;
+	num_dests -= num_dests_reduce;
+
+	/* update tracker header */
+	mcast_tracker->num_dests = htons(num_dests);
+
+	/* update tracker's tvlv header's length field */
+	tvlv_hdr = (struct batadv_tvlv_hdr *)(skb_network_header(skb) -
+					      sizeof(*tvlv_hdr));
+	tvlv_hdr->len = htons(ntohs(tvlv_hdr->len) - offset);
+
+	/* update multicast packet header's tvlv length field */
+	mcast_packet = (struct batadv_mcast_packet *)skb->data;
+	mcast_packet->tvlv_len = htons(ntohs(mcast_packet->tvlv_len) - offset);
+
+	return offset;
+}
+
+/**
+ * batadv_mcast_forw_shrink_move_headers() - move multicast headers by offset
+ * @skb: the batman-adv multicast packet to move headers for
+ * @offset: a non-negative offset to move headers by, towards the skb tail
+ *
+ * Moves the batman-adv multicast packet header, its multicast tracker TVLV and
+ * any TVLVs in between by the given offset in direction towards the tail.
+ */
+static void
+batadv_mcast_forw_shrink_move_headers(struct sk_buff *skb, unsigned int offset)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	unsigned char *skb_net_hdr;
+	unsigned int len;
+	u16 num_dests;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests = ntohs(mcast_tracker->num_dests);
+	len = skb_network_offset(skb) + sizeof(*mcast_tracker);
+	len += num_dests * ETH_ALEN;
+
+	batadv_mcast_forw_scrape(skb, len, offset);
+}
+
+/**
+ * batadv_mcast_forw_shrink_tracker() - remove zero addresses in a tracker tvlv
+ * @skb: the batman-adv multicast packet to (potentially) shrink
+ *
+ * Removes all destinations with a zero MAC addresses (00:00:00:00:00:00) from
+ * the given batman-adv multicast packet's tracker TVLV and updates headers
+ * accordingly to maintain a valid batman-adv multicast packet.
+ */
+static void batadv_mcast_forw_shrink_tracker(struct sk_buff *skb)
+{
+	unsigned int offset;
+	u16 dests_reduced;
+
+	dests_reduced = batadv_mcast_forw_shrink_pack_dests(skb);
+	if (!dests_reduced)
+		return;
+
+	offset = batadv_mcast_forw_shrink_update_headers(skb, dests_reduced);
+	batadv_mcast_forw_shrink_move_headers(skb, offset);
+}
+
+/**
+ * batadv_mcast_forw_packet() - forward a batman-adv multicast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the received or locally generated batman-adv multicast packet
+ * @local_xmit: indicates that the packet was locally generated and not received
+ *
+ * Parses the tracker TVLV of a batman-adv multicast packet and forwards the
+ * packet as indicated in this TVLV.
+ *
+ * Caller needs to set the skb network header to the start of the multicast
+ * tracker TVLV (excluding the generic TVLV header) and the skb transport header
+ * to the next byte after this multicast tracker TVLV.
+ *
+ * Caller needs to free the skb.
+ *
+ * Return: NET_RX_SUCCESS or NET_RX_DROP on success or a negative error
+ * code on failure. NET_RX_SUCCESS if the received packet is supposed to be
+ * decapsulated and forwarded to the own soft interface, NET_RX_DROP otherwise.
+ */
+static int batadv_mcast_forw_packet(struct batadv_priv *bat_priv,
+				    struct sk_buff *skb, bool local_xmit)
+{
+	struct batadv_tvlv_mcast_tracker *mcast_tracker;
+	struct batadv_neigh_node *neigh_node;
+	unsigned long offset, num_dests_off;
+	struct sk_buff *nexthop_skb;
+	unsigned char *skb_net_hdr;
+	bool local_recv = false;
+	unsigned int tvlv_len;
+	bool xmitted = false;
+	u8 *dest, *next_dest;
+	u16 num_dests;
+	int ret;
+
+	/* (at least) TVLV part needs to be linearized */
+	SKB_LINEAR_ASSERT(skb);
+
+	/* check if num_dests is within skb length */
+	num_dests_off = offsetof(struct batadv_tvlv_mcast_tracker, num_dests);
+	if (num_dests_off > skb_network_header_len(skb))
+		return -EINVAL;
+
+	skb_net_hdr = skb_network_header(skb);
+	mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+	num_dests = ntohs(mcast_tracker->num_dests);
+
+	dest = (u8 *)mcast_tracker + sizeof(*mcast_tracker);
+
+	/* check if full tracker tvlv is within skb length */
+	tvlv_len = sizeof(*mcast_tracker) + ETH_ALEN * num_dests;
+	if (tvlv_len > skb_network_header_len(skb))
+		return -EINVAL;
+
+	/* invalidate checksum: */
+	skb->ip_summed = CHECKSUM_NONE;
+
+	batadv_mcast_forw_tracker_for_each_dest(dest, num_dests) {
+		if (is_zero_ether_addr(dest))
+			continue;
+
+		/* only unicast originator addresses supported */
+		if (is_multicast_ether_addr(dest)) {
+			eth_zero_addr(dest);
+			continue;
+		}
+
+		if (batadv_is_my_mac(bat_priv, dest)) {
+			eth_zero_addr(dest);
+			local_recv = true;
+			continue;
+		}
+
+		neigh_node = batadv_orig_to_router(bat_priv, dest, NULL);
+		if (!neigh_node) {
+			eth_zero_addr(dest);
+			continue;
+		}
+
+		nexthop_skb = skb_copy(skb, GFP_ATOMIC);
+		if (!nexthop_skb) {
+			batadv_neigh_node_put(neigh_node);
+			return -ENOMEM;
+		}
+
+		offset = dest - skb->data;
+		next_dest = nexthop_skb->data + offset;
+
+		batadv_mcast_forw_scrub_dests(bat_priv, neigh_node, dest,
+					      next_dest, num_dests);
+		batadv_mcast_forw_shrink_tracker(nexthop_skb);
+
+		batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_TX);
+		batadv_add_counter(bat_priv, BATADV_CNT_MCAST_TX_BYTES,
+				   nexthop_skb->len + ETH_HLEN);
+		xmitted = true;
+		ret = batadv_send_unicast_skb(nexthop_skb, neigh_node);
+
+		batadv_neigh_node_put(neigh_node);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	if (xmitted) {
+		if (local_xmit) {
+			batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_TX_LOCAL);
+			batadv_add_counter(bat_priv,
+					   BATADV_CNT_MCAST_TX_LOCAL_BYTES,
+					   skb->len -
+					   skb_transport_offset(skb));
+		} else {
+			batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_FWD);
+			batadv_add_counter(bat_priv, BATADV_CNT_MCAST_FWD_BYTES,
+					   skb->len + ETH_HLEN);
+		}
+	}
+
+	if (local_recv)
+		return NET_RX_SUCCESS;
+	else
+		return NET_RX_DROP;
+}
+
+/**
+ * batadv_mcast_forw_tracker_tvlv_handler() - handle an mcast tracker tvlv
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the received batman-adv multicast packet
+ *
+ * Parses the tracker TVLV of an incoming batman-adv multicast packet and
+ * forwards the packet as indicated in this TVLV.
+ *
+ * Caller needs to set the skb network header to the start of the multicast
+ * tracker TVLV (excluding the generic TVLV header) and the skb transport header
+ * to the next byte after this multicast tracker TVLV.
+ *
+ * Caller needs to free the skb.
+ *
+ * Return: NET_RX_SUCCESS or NET_RX_DROP on success or a negative error
+ * code on failure. NET_RX_SUCCESS if the received packet is supposed to be
+ * decapsulated and forwarded to the own soft interface, NET_RX_DROP otherwise.
+ */
+int batadv_mcast_forw_tracker_tvlv_handler(struct batadv_priv *bat_priv,
+					   struct sk_buff *skb)
+{
+	return batadv_mcast_forw_packet(bat_priv, skb, false);
+}
+
+/**
+ * batadv_mcast_forw_packet_hdrlen() - multicast packet header length
+ * @num_dests: number of destination nodes
+ *
+ * Calculates the total batman-adv multicast packet header length for a given
+ * number of destination nodes (excluding the outer ethernet frame).
+ *
+ * Return: The calculated total batman-adv multicast packet header length.
+ */
+unsigned int batadv_mcast_forw_packet_hdrlen(unsigned int num_dests)
+{
+	/**
+	 * If the number of destination entries is even then we need to add
+	 * two byte padding to the tracker TVLV.
+	 */
+	int padding = (!(num_dests % 2)) ? 2 : 0;
+
+	return padding + num_dests * ETH_ALEN +
+	       sizeof(struct batadv_tvlv_mcast_tracker) +
+	       sizeof(struct batadv_tvlv_hdr) +
+	       sizeof(struct batadv_mcast_packet);
+}
+
+/**
+ * batadv_mcast_forw_expand_head() - expand headroom for an mcast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to send
+ *
+ * Tries to expand an skb's headroom so that its head to tail is 1298
+ * bytes (minimum IPv6 MTU + vlan ethernet header size) large.
+ *
+ * Return: -EINVAL if the given skb's length is too large or -ENOMEM on memory
+ * allocation failure. Otherwise, on success, zero is returned.
+ */
+static int batadv_mcast_forw_expand_head(struct batadv_priv *bat_priv,
+					 struct sk_buff *skb)
+{
+	int hdr_size = VLAN_ETH_HLEN + IPV6_MIN_MTU - skb->len;
+
+	 /* TODO: Could be tightened to actual number of destination nodes?
+	  * But it's tricky, number of destinations might have increased since
+	  * we last checked.
+	  */
+	if (hdr_size < 0) {
+		/* batadv_mcast_forw_mode_check_count() should ensure we do not
+		 * end up here
+		 */
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	if (skb_headroom(skb) < hdr_size &&
+	    pskb_expand_head(skb, hdr_size, 0, GFP_ATOMIC) < 0)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * batadv_mcast_forw_push() - encapsulate skb in a batman-adv multicast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to encapsulate and send
+ * @vid: the vlan identifier
+ * @is_routable: indicates whether the destination is routable
+ * @count: the number of originators the multicast packet needs to be sent to
+ *
+ * Encapsulates the given multicast packet in a batman-adv multicast packet.
+ * A multicast tracker TVLV with destination originator addresses for any node
+ * that signaled interest in it, that is either via the translation table or the
+ * according want-all flags, is attached accordingly.
+ *
+ * Return: true on success, false otherwise.
+ */
+bool batadv_mcast_forw_push(struct batadv_priv *bat_priv, struct sk_buff *skb,
+			    unsigned short vid, int is_routable, int count)
+{
+	unsigned short tvlv_len = 0;
+	int ret;
+
+	if (batadv_mcast_forw_expand_head(bat_priv, skb) < 0)
+		goto err;
+
+	skb_reset_transport_header(skb);
+
+	ret = batadv_mcast_forw_push_tvlvs(bat_priv, skb, vid, is_routable,
+					   count, &tvlv_len);
+	if (ret < 0)
+		goto err;
+
+	ret = batadv_mcast_forw_push_hdr(skb, tvlv_len);
+	if (ret < 0)
+		goto err;
+
+	return true;
+
+err:
+	if (tvlv_len)
+		skb_pull(skb, tvlv_len);
+
+	return false;
+}
+
+/**
+ * batadv_mcast_forw_mcsend() - send a self prepared batman-adv multicast packet
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to encapsulate and send
+ *
+ * Transmits a batman-adv multicast packet that was locally prepared and
+ * consumes/frees it.
+ *
+ * Return: NET_XMIT_DROP on memory allocation failure. NET_XMIT_SUCCESS
+ * otherwise.
+ */
+int batadv_mcast_forw_mcsend(struct batadv_priv *bat_priv,
+			     struct sk_buff *skb)
+{
+	int ret = batadv_mcast_forw_packet(bat_priv, skb, true);
+
+	if (ret < 0) {
+		kfree_skb(skb);
+		return NET_XMIT_DROP;
+	}
+
+	consume_skb(skb);
+	return NET_XMIT_SUCCESS;
+}

net/batman-adv/netlink.c

@@ -7,6 +7,7 @@
 #include "netlink.h"
 #include "main.h"
 
+#include <linux/array_size.h>
 #include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/bug.h>
@@ -20,7 +21,6 @@
 #include <linux/if_ether.h>
 #include <linux/if_vlan.h>
 #include <linux/init.h>
-#include <linux/kernel.h>
 #include <linux/limits.h>
 #include <linux/list.h>
 #include <linux/minmax.h>

net/batman-adv/originator.c

@@ -311,6 +311,33 @@ batadv_orig_router_get(struct batadv_orig_node *orig_node,
 	return router;
 }
 
+/**
+ * batadv_orig_to_router() - get next hop neighbor to an orig address
+ * @bat_priv: the bat priv with all the soft interface information
+ * @orig_addr: the originator MAC address to search the best next hop router for
+ * @if_outgoing: the interface where the payload packet has been received or
+ *  the OGM should be sent to
+ *
+ * Return: A neighbor node which is the best router towards the given originator
+ * address.
+ */
+struct batadv_neigh_node *
+batadv_orig_to_router(struct batadv_priv *bat_priv, u8 *orig_addr,
+		      struct batadv_hard_iface *if_outgoing)
+{
+	struct batadv_neigh_node *neigh_node;
+	struct batadv_orig_node *orig_node;
+
+	orig_node = batadv_orig_hash_find(bat_priv, orig_addr);
+	if (!orig_node)
+		return NULL;
+
+	neigh_node = batadv_find_router(bat_priv, orig_node, if_outgoing);
+	batadv_orig_node_put(orig_node);
+
+	return neigh_node;
+}
+
 /**
  * batadv_orig_ifinfo_get() - find the ifinfo from an orig_node
  * @orig_node: the orig node to be queried
@@ -942,6 +969,7 @@ struct batadv_orig_node *batadv_orig_node_new(struct batadv_priv *bat_priv,
 #ifdef CONFIG_BATMAN_ADV_MCAST
 	orig_node->mcast_flags = BATADV_MCAST_WANT_NO_RTR4;
 	orig_node->mcast_flags |= BATADV_MCAST_WANT_NO_RTR6;
+	orig_node->mcast_flags |= BATADV_MCAST_HAVE_MC_PTYPE_CAPA;
 	INIT_HLIST_NODE(&orig_node->mcast_want_all_unsnoopables_node);
 	INIT_HLIST_NODE(&orig_node->mcast_want_all_ipv4_node);
 	INIT_HLIST_NODE(&orig_node->mcast_want_all_ipv6_node);

net/batman-adv/originator.h

@@ -36,6 +36,9 @@ void batadv_neigh_node_release(struct kref *ref);
 struct batadv_neigh_node *
 batadv_orig_router_get(struct batadv_orig_node *orig_node,
 		       const struct batadv_hard_iface *if_outgoing);
+struct batadv_neigh_node *
+batadv_orig_to_router(struct batadv_priv *bat_priv, u8 *orig_addr,
+		      struct batadv_hard_iface *if_outgoing);
 struct batadv_neigh_ifinfo *
 batadv_neigh_ifinfo_new(struct batadv_neigh_node *neigh,
 			struct batadv_hard_iface *if_outgoing);

net/batman-adv/routing.c

@@ -1270,3 +1270,73 @@ int batadv_recv_bcast_packet(struct sk_buff *skb,
 	batadv_orig_node_put(orig_node);
 	return ret;
 }
+
+#ifdef CONFIG_BATMAN_ADV_MCAST
+/**
+ * batadv_recv_mcast_packet() - process received batman-adv multicast packet
+ * @skb: the received batman-adv multicast packet
+ * @recv_if: interface that the skb is received on
+ *
+ * Parses the given, received batman-adv multicast packet. Depending on the
+ * contents of its TVLV forwards it and/or decapsulates it to hand it to the
+ * soft interface.
+ *
+ * Return: NET_RX_DROP if the skb is not consumed, NET_RX_SUCCESS otherwise.
+ */
+int batadv_recv_mcast_packet(struct sk_buff *skb,
+			     struct batadv_hard_iface *recv_if)
+{
+	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
+	struct batadv_mcast_packet *mcast_packet;
+	int hdr_size = sizeof(*mcast_packet);
+	unsigned char *tvlv_buff;
+	int ret = NET_RX_DROP;
+	u16 tvlv_buff_len;
+
+	if (batadv_check_unicast_packet(bat_priv, skb, hdr_size) < 0)
+		goto free_skb;
+
+	/* create a copy of the skb, if needed, to modify it. */
+	if (skb_cow(skb, ETH_HLEN) < 0)
+		goto free_skb;
+
+	/* packet needs to be linearized to access the tvlv content */
+	if (skb_linearize(skb) < 0)
+		goto free_skb;
+
+	mcast_packet = (struct batadv_mcast_packet *)skb->data;
+	if (mcast_packet->ttl-- < 2)
+		goto free_skb;
+
+	tvlv_buff = (unsigned char *)(skb->data + hdr_size);
+	tvlv_buff_len = ntohs(mcast_packet->tvlv_len);
+
+	if (tvlv_buff_len > skb->len - hdr_size)
+		goto free_skb;
+
+	ret = batadv_tvlv_containers_process(bat_priv, BATADV_MCAST, NULL, skb,
+					     tvlv_buff, tvlv_buff_len);
+	if (ret >= 0) {
+		batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_RX);
+		batadv_add_counter(bat_priv, BATADV_CNT_MCAST_RX_BYTES,
+				   skb->len + ETH_HLEN);
+	}
+
+	hdr_size += tvlv_buff_len;
+
+	if (ret == NET_RX_SUCCESS && (skb->len - hdr_size >= ETH_HLEN)) {
+		batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_RX_LOCAL);
+		batadv_add_counter(bat_priv, BATADV_CNT_MCAST_RX_LOCAL_BYTES,
+				   skb->len - hdr_size);
+
+		batadv_interface_rx(bat_priv->soft_iface, skb, hdr_size, NULL);
+		/* skb was consumed */
+		skb = NULL;
+	}
+
+free_skb:
+	kfree_skb(skb);
+
+	return ret;
+}
+#endif /* CONFIG_BATMAN_ADV_MCAST */

net/batman-adv/routing.h

@@ -27,6 +27,17 @@ int batadv_recv_frag_packet(struct sk_buff *skb,
 			    struct batadv_hard_iface *iface);
 int batadv_recv_bcast_packet(struct sk_buff *skb,
 			     struct batadv_hard_iface *recv_if);
+#ifdef CONFIG_BATMAN_ADV_MCAST
+int batadv_recv_mcast_packet(struct sk_buff *skb,
+			     struct batadv_hard_iface *recv_if);
+#else
+static inline int batadv_recv_mcast_packet(struct sk_buff *skb,
+					   struct batadv_hard_iface *recv_if)
+{
+	kfree_skb(skb);
+	return NET_RX_DROP;
+}
+#endif
 int batadv_recv_unicast_tvlv(struct sk_buff *skb,
 			     struct batadv_hard_iface *recv_if);
 int batadv_recv_unhandled_unicast_packet(struct sk_buff *skb,

net/batman-adv/soft-interface.c

@@ -301,12 +301,13 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
 
 send:
 		if (do_bcast && !is_broadcast_ether_addr(ethhdr->h_dest)) {
-			forw_mode = batadv_mcast_forw_mode(bat_priv, skb,
+			forw_mode = batadv_mcast_forw_mode(bat_priv, skb, vid,
 							   &mcast_is_routable);
 			switch (forw_mode) {
 			case BATADV_FORW_BCAST:
 				break;
 			case BATADV_FORW_UCASTS:
+			case BATADV_FORW_MCAST:
 				do_bcast = false;
 				break;
 			case BATADV_FORW_NONE:
@@ -365,6 +366,8 @@ static netdev_tx_t batadv_interface_tx(struct sk_buff *skb,
 		} else if (forw_mode == BATADV_FORW_UCASTS) {
 			ret = batadv_mcast_forw_send(bat_priv, skb, vid,
 						     mcast_is_routable);
+		} else if (forw_mode == BATADV_FORW_MCAST) {
+			ret = batadv_mcast_forw_mcsend(bat_priv, skb);
 		} else {
 			if (batadv_dat_snoop_outgoing_arp_request(bat_priv,
 								  skb))
@@ -762,6 +765,7 @@ static int batadv_softif_init_late(struct net_device *dev)
 	atomic_set(&bat_priv->mcast.num_want_all_unsnoopables, 0);
 	atomic_set(&bat_priv->mcast.num_want_all_ipv4, 0);
 	atomic_set(&bat_priv->mcast.num_want_all_ipv6, 0);
+	atomic_set(&bat_priv->mcast.num_no_mc_ptype_capa, 0);
 #endif
 	atomic_set(&bat_priv->gw.mode, BATADV_GW_MODE_OFF);
 	atomic_set(&bat_priv->gw.bandwidth_down, 100);
@@ -925,6 +929,18 @@ static const struct {
 	{ "tt_response_rx" },
 	{ "tt_roam_adv_tx" },
 	{ "tt_roam_adv_rx" },
+#ifdef CONFIG_BATMAN_ADV_MCAST
+	{ "mcast_tx" },
+	{ "mcast_tx_bytes" },
+	{ "mcast_tx_local" },
+	{ "mcast_tx_local_bytes" },
+	{ "mcast_rx" },
+	{ "mcast_rx_bytes" },
+	{ "mcast_rx_local" },
+	{ "mcast_rx_local_bytes" },
+	{ "mcast_fwd" },
+	{ "mcast_fwd_bytes" },
+#endif
 #ifdef CONFIG_BATMAN_ADV_DAT
 	{ "dat_get_tx" },
 	{ "dat_get_rx" },

net/batman-adv/types.h

@@ -862,6 +862,70 @@ enum batadv_counters {
 	 */
 	BATADV_CNT_TT_ROAM_ADV_RX,
 
+#ifdef CONFIG_BATMAN_ADV_MCAST
+	/**
+	 * @BATADV_CNT_MCAST_TX: transmitted batman-adv multicast packets
+	 *  counter
+	 */
+	BATADV_CNT_MCAST_TX,
+
+	/**
+	 * @BATADV_CNT_MCAST_TX_BYTES: transmitted batman-adv multicast packets
+	 *  bytes counter
+	 */
+	BATADV_CNT_MCAST_TX_BYTES,
+
+	/**
+	 * @BATADV_CNT_MCAST_TX_LOCAL: counter for multicast packets which
+	 *  were locally encapsulated and transmitted as batman-adv multicast
+	 *  packets
+	 */
+	BATADV_CNT_MCAST_TX_LOCAL,
+
+	/**
+	 * @BATADV_CNT_MCAST_TX_LOCAL_BYTES: bytes counter for multicast packets
+	 *  which were locally encapsulated and transmitted as batman-adv
+	 *  multicast packets
+	 */
+	BATADV_CNT_MCAST_TX_LOCAL_BYTES,
+
+	/**
+	 * @BATADV_CNT_MCAST_RX: received batman-adv multicast packet counter
+	 */
+	BATADV_CNT_MCAST_RX,
+
+	/**
+	 * @BATADV_CNT_MCAST_RX_BYTES: received batman-adv multicast packet
+	 *  bytes counter
+	 */
+	BATADV_CNT_MCAST_RX_BYTES,
+
+	/**
+	 * @BATADV_CNT_MCAST_RX_LOCAL: counter for received batman-adv multicast
+	 *  packets which were forwarded to the local soft interface
+	 */
+	BATADV_CNT_MCAST_RX_LOCAL,
+
+	/**
+	 * @BATADV_CNT_MCAST_RX_LOCAL_BYTES: bytes counter for received
+	 *  batman-adv multicast packets which were forwarded to the local soft
+	 *  interface
+	 */
+	BATADV_CNT_MCAST_RX_LOCAL_BYTES,
+
+	/**
+	 * @BATADV_CNT_MCAST_FWD: counter for received batman-adv multicast
+	 *  packets which were forwarded to other, neighboring nodes
+	 */
+	BATADV_CNT_MCAST_FWD,
+
+	/**
+	 * @BATADV_CNT_MCAST_FWD_BYTES: bytes counter for received batman-adv
+	 *  multicast packets which were forwarded to other, neighboring nodes
+	 */
+	BATADV_CNT_MCAST_FWD_BYTES,
+#endif
+
 #ifdef CONFIG_BATMAN_ADV_DAT
 	/**
 	 * @BATADV_CNT_DAT_GET_TX: transmitted dht GET traffic packet counter
@@ -1278,6 +1342,12 @@ struct batadv_priv_mcast {
 	/** @num_want_all_rtr6: counter for items in want_all_rtr6_list */
 	atomic_t num_want_all_rtr6;
 
+	/**
+	 * @num_no_mc_ptype_capa: counter for number of nodes without the
+	 *  BATADV_MCAST_HAVE_MC_PTYPE_CAPA flag
+	 */
+	atomic_t num_no_mc_ptype_capa;
+
 	/**
 	 * @want_lists_lock: lock for protecting modifications to mcasts
 	 *  want_all_{unsnoopables,ipv4,ipv6}_list (traversals are rcu-locked)