[PATCH v2 0/2] batman-adv: Add routeable multicast optimizations

[PATCH v2 0/2] batman-adv: Add routeable multicast optimizations

[Linus Lüssing]

The following patchset fills the next gaps in the multicast address
rules page by adding support for group-aware optimizations for
multicast addresses of scope greater than link-local. So far, only
link-local addresses were optimized as packets with routeable
addresses not only need to be forwarded to local multicast listeners
but also multicast routers.

"Handling rules depending on multicast address:" [0]

Before:

* Ipv4, link-local: supported without bridges
* IPv6, link-local: supported
* IPv4, routeable: support planned.
* IPv6, routeable: support planned.

After:

* Ipv4, link-local: supported without bridges
* IPv6, link-local: supported
* IPv4, routeable: supported without bridges.
* IPv6, routeable: supported.

Patch 1 adds the detection of multicast routers and announces
them via two new flags in its multicast TVLV. TVLV receivers will
memorize this and fill lists similar to how we already do for the
WANT_ALL_IPV4/IPV6 flags. Currently the detection for bridged-in
IPv6 multicast routers is not quite what the RFC for multicast router
discovery suggests. But once the MRD implementation in the Linux bridge
has matured a bit, I'm going to swap this simplified approach with
tapping into the bridge once more, asking the bridge for the presence of
multicast routers on the link. (This will then also add support for
"IPv4, routeable, with bridges")

Then patch 2 implements the changes to the forwarding plane,
utilizing the new information we have gathered with the second patch.

This patchset is rebased to:

"[PATCH v3 0/3] batman-adv: routeable multicast preparations"
https://patchwork.open-mesh.org/project/b.a.t.m.a.n./list/?series=252


Regards, Linus

[0]: https://www.open-mesh.org/projects/batman-adv/wiki/Multicast-optimizations-tech#Handling-rules-depending-on-multicast-address

---

Changelog v2:

* rebased to master
* split patchset in two with the intention to ease reviewing
  (no code changes, just the last two patches here)

* removed unncessarilly added newline in batadv_mcast_flags_log()
  [PATCH 5/6] / [PATCH v2 1/2]
* kerneldoc: @BATADV_MCAST_NO_WANT_ALL_RTR6 -> -"NO_"
  in enum batadv_mcast_flags [PATCH 5/6] / [PATCH v2 1/2]

[PATCH v2 1/2] batman-adv: mcast: detect, distribute and maintain multicast router presence

[Linus Lüssing]

To be able to apply our group aware multicast optimizations to packets
with a scope greater than link-local we need to not only keep track of
multicast listeners but also multicast routers.

With this patch a node detects the presence of multicast routers on
its segment by checking if
/proc/sys/net/ipv{4,6}/conf/<bat0|br0(bat)>/mc_forwarding is set for one
thing. This option is enabled by multicast routing daemons and needed
for the kernel's multicast routing tables to receive and route packets.

For another thing if a bridge is configured on top of bat0 then the
presence of an IPv6 multicast router behind this bridge is currently
detected by checking for an IPv6 multicast "All Routers Address"
(ff02::2). This should later be replaced by querying the bridge, which
performs proper, RFC4286 compliant Multicast Router Discovery (our
simplified approach includes more hosts than necessary, most notably
not just multicast routers but also unicast ones and is not applicable
for IPv4).

If a multicast router is detected then this is signalized via the new
BATADV_MCAST_WANT_ALL_RTR4 and BATADV_MCAST_WANT_ALL_RTR6
multicast tvlv flags (which are sent flipped over the wire for backwards
compatibility - so that old nodes will always have them "set").

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 include/uapi/linux/batadv_packet.h |   8 +
 net/batman-adv/multicast.c         | 357 ++++++++++++++++++++++++-----
 net/batman-adv/types.h             |  29 +++
 3 files changed, 343 insertions(+), 51 deletions(-)

diff --git a/include/uapi/linux/batadv_packet.h b/include/uapi/linux/batadv_packet.h
index 4ebc2135..a38ce796 100644
--- a/include/uapi/linux/batadv_packet.h
+++ b/include/uapi/linux/batadv_packet.h
@@ -107,12 +107,20 @@ enum batadv_icmp_packettype {
  * @BATADV_MCAST_WANT_ALL_UNSNOOPABLES: we want all packets destined for
  *  224.0.0.0/24 or ff02::1
  * @BATADV_MCAST_WANT_ALL_IPV4: we want all IPv4 multicast packets
+ *  (both link-local and routeable ones)
  * @BATADV_MCAST_WANT_ALL_IPV6: we want all IPv6 multicast packets
+ *  (both link-local and routable ones)
+ * @BATADV_MCAST_WANT_ALL_RTR4: we want all routeable IPv4 multicast packets
+ *  (send flipped on the wire)
+ * @BATADV_MCAST_WANT_ALL_RTR6: we want all routeable IPv6 multicast packets
+ *  (send flipped on the wire)
  */
 enum batadv_mcast_flags {
 	BATADV_MCAST_WANT_ALL_UNSNOOPABLES	= 1UL << 0,
 	BATADV_MCAST_WANT_ALL_IPV4		= 1UL << 1,
 	BATADV_MCAST_WANT_ALL_IPV6		= 1UL << 2,
+	BATADV_MCAST_WANT_ALL_RTR4		= 1UL << 3,
+	BATADV_MCAST_WANT_ALL_RTR6		= 1UL << 4,
 };
 
 /* tt data subtypes */
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 90571e4c..a87fb596 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -73,26 +73,143 @@ static void batadv_mcast_start_timer(struct batadv_priv *bat_priv)
 }
 
 /**
- * batadv_mcast_has_bridge() - check whether the soft-iface is bridged
- * @bat_priv: the bat priv with all the soft interface information
+ * batadv_mcast_get_bridge() - get the bridge on top of the softif if it exists
+ * @soft_iface: netdev struct of the mesh interface
  *
- * Checks whether there is a bridge on top of our soft interface.
+ * If the given soft interface has a bridge on top then the refcount
+ * of the according net device is increased.
  *
- * Return: true if there is a bridge, false otherwise.
+ * Return: NULL if no such bridge exists. Otherwise the net device of the
+ * bridge.
  */
-static bool batadv_mcast_has_bridge(struct batadv_priv *bat_priv)
+static struct net_device *batadv_mcast_get_bridge(struct net_device *soft_iface)
 {
-	struct net_device *upper = bat_priv->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_rtr_flags_softif_get() - get mcast router flags from node
+ * @bat_priv: the bat priv with all the soft interface information
+ * @bridge: bridge interface on top of the soft_iface if present,
+ *  otherwise pass NULL
+ *
+ * Checks the presence of IPv4 and IPv6 multicast routers on this
+ * node.
+ *
+ * Return:
+ *	BATADV_NO_FLAGS: no multicast router is present
+ *	BATADV_MCAST_WANT_ALL_RTR4: An IPv4 multicast router is present
+ *	BATADV_MCAST_WANT_ALL_RTR6: An IPv6 multicast router is present
+ *	The former two OR'd: Both an IPv4 and IPv6 multicast router is present
+ */
+static u8 batadv_mcast_mla_rtr_flags_softif_get(struct batadv_priv *bat_priv,
+						struct net_device *bridge)
+{
+	struct net_device *dev = bridge ? bridge : bat_priv->soft_iface;
+	u8 flags = BATADV_NO_FLAGS;
+	struct inet6_dev *in6_dev;
+	struct in_device *in_dev;
+
+	rcu_read_lock();
+	in_dev = __in_dev_get_rcu(dev);
+	if (in_dev && IN_DEV_MFORWARD(in_dev))
+		flags |= BATADV_MCAST_WANT_ALL_RTR4;
+
+	in6_dev = __in6_dev_get(dev);
+	if (in6_dev && in6_dev->cnf.mc_forwarding)
+		flags |= BATADV_MCAST_WANT_ALL_RTR6;
+	rcu_read_unlock();
+
+	return flags;
+}
+
+/**
+ * batadv_mcast_mla_rtr_flags_bridge_get() - get mcast router flags from bridge
+ * @bat_priv: the bat priv with all the soft interface information
+ * @bridge: bridge interface on top of the soft_iface if present,
+ *  otherwise pass NULL
+ *
+ * Checks the presence of IPv4 and IPv6 multicast routers behind a bridge.
+ *
+ * Return:
+ *	BATADV_NO_FLAGS: no multicast router is present
+ *	BATADV_MCAST_WANT_ALL_RTR4: An IPv4 multicast router is present
+ *	BATADV_MCAST_WANT_ALL_RTR6: An IPv6 multicast router is present
+ *	The former two OR'd: Both an IPv4 and IPv6 multicast router is present
+ */
+static u8 batadv_mcast_mla_rtr_flags_bridge_get(struct batadv_priv *bat_priv,
+						struct net_device *bridge)
+{
+	struct list_head bridge_mcast_list = LIST_HEAD_INIT(bridge_mcast_list);
+	struct net_device *dev = bat_priv->soft_iface;
+	u8 flags = BATADV_MCAST_WANT_ALL_RTR4;
+	struct br_ip_list *br_ip_entry, *tmp;
+	int ret;
+
+	if (!bridge)
+		return BATADV_NO_FLAGS;
+
+	/* TODO: ask the bridge if a multicast router is present (the bridge
+	 * is capable of performing proper RFC4286 multicast multicast router
+	 * discovery) instead of searching for a ff02::2 listener here
+	 */
+	ret = br_multicast_list_adjacent(dev, &bridge_mcast_list);
+	if (ret < 0)
+		return flags | BATADV_MCAST_WANT_ALL_RTR6;
+
+	list_for_each_entry_safe(br_ip_entry, tmp, &bridge_mcast_list, list) {
+		/* the bridge snooping does not maintain IPv4 link-local
+		 * addresses - therefore we won't find any IPv4 multicast router
+		 * address here, only IPv6 ones
+		 */
+		if (br_ip_entry->addr.proto == htons(ETH_P_IPV6) &&
+		    ipv6_addr_is_ll_all_routers(&br_ip_entry->addr.u.ip6))
+			flags |= BATADV_MCAST_WANT_ALL_RTR6;
+
+		list_del(&br_ip_entry->list);
+		kfree(br_ip_entry);
+	}
+
+	return flags;
+}
+
+/**
+ * batadv_mcast_mla_rtr_flags_get() - get multicast router flags
+ * @bat_priv: the bat priv with all the soft interface information
+ * @bridge: bridge interface on top of the soft_iface if present,
+ *  otherwise pass NULL
+ *
+ * Checks the presence of IPv4 and IPv6 multicast routers on this
+ * node or behind its bridge.
+ *
+ * Return:
+ *	BATADV_NO_FLAGS: no multicast router is present
+ *	BATADV_MCAST_WANT_ALL_RTR4: An IPv4 multicast router is present
+ *	BATADV_MCAST_WANT_ALL_RTR6: An IPv6 multicast router is present
+ *	The former two OR'd: Both an IPv4 and IPv6 multicast router is present
+ */
+static u8 batadv_mcast_mla_rtr_flags_get(struct batadv_priv *bat_priv,
+					 struct net_device *bridge)
+{
+	u8 flags = BATADV_NO_FLAGS;
+
+	flags |= batadv_mcast_mla_rtr_flags_softif_get(bat_priv, bridge);
+	flags |= batadv_mcast_mla_rtr_flags_bridge_get(bat_priv, bridge);
+
+	return flags;
+}
+
 /**
  * batadv_mcast_mla_flags_get() - get the new multicast flags
  * @bat_priv: the bat priv with all the soft interface information
@@ -106,13 +223,20 @@ batadv_mcast_mla_flags_get(struct batadv_priv *bat_priv)
 	struct net_device *dev = bat_priv->soft_iface;
 	struct batadv_mcast_querier_state *qr4, *qr6;
 	struct batadv_mcast_mla_flags mla_flags;
+	struct net_device *bridge;
+
+	bridge = batadv_mcast_get_bridge(dev);
 
 	memset(&mla_flags, 0, sizeof(mla_flags));
 	mla_flags.enabled = 1;
+	mla_flags.tvlv_flags |= batadv_mcast_mla_rtr_flags_get(bat_priv,
+							       bridge);
 
-	if (!batadv_mcast_has_bridge(bat_priv))
+	if (!bridge)
 		return mla_flags;
 
+	dev_put(bridge);
+
 	mla_flags.bridged = 1;
 	qr4 = &mla_flags.querier_ipv4;
 	qr6 = &mla_flags.querier_ipv6;
@@ -146,32 +270,6 @@ batadv_mcast_mla_flags_get(struct batadv_priv *bat_priv)
 	return mla_flags;
 }
 
-/**
- * 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_is_duplicate() - check whether an address is in a list
  * @mcast_addr: the multicast address to check
@@ -231,6 +329,10 @@ batadv_mcast_mla_softif_get_ipv4(struct net_device *dev,
 		    ipv4_is_local_multicast(pmc->multiaddr))
 			continue;
 
+		if (flags->tvlv_flags & BATADV_MCAST_WANT_ALL_RTR4 &&
+		    !ipv4_is_local_multicast(pmc->multiaddr))
+			continue;
+
 		ip_eth_mc_map(pmc->multiaddr, mcast_addr);
 
 		if (batadv_mcast_mla_is_duplicate(mcast_addr, mcast_list))
@@ -295,6 +397,11 @@ batadv_mcast_mla_softif_get_ipv6(struct net_device *dev,
 		    ipv6_addr_is_ll_all_nodes(&pmc6->mca_addr))
 			continue;
 
+		if (flags->tvlv_flags & BATADV_MCAST_WANT_ALL_RTR6 &&
+		    IPV6_ADDR_MC_SCOPE(&pmc6->mca_addr) >
+		    IPV6_ADDR_SCOPE_LINKLOCAL)
+			continue;
+
 		ipv6_eth_mc_map(&pmc6->mca_addr, mcast_addr);
 
 		if (batadv_mcast_mla_is_duplicate(mcast_addr, mcast_list))
@@ -436,6 +543,10 @@ static int batadv_mcast_mla_bridge_get(struct net_device *dev,
 			if (tvlv_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
 			    ipv4_is_local_multicast(br_ip_entry->addr.u.ip4))
 				continue;
+
+			if (tvlv_flags & BATADV_MCAST_WANT_ALL_RTR4 &&
+			    !ipv4_is_local_multicast(br_ip_entry->addr.u.ip4))
+				continue;
 		}
 
 		if (br_ip_entry->addr.proto == htons(ETH_P_IPV6)) {
@@ -445,6 +556,11 @@ static int batadv_mcast_mla_bridge_get(struct net_device *dev,
 			if (tvlv_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
 			    ipv6_addr_is_ll_all_nodes(&br_ip_entry->addr.u.ip6))
 				continue;
+
+			if (tvlv_flags & BATADV_MCAST_WANT_ALL_RTR6 &&
+			    IPV6_ADDR_MC_SCOPE(&br_ip_entry->addr.u.ip6) >
+			    IPV6_ADDR_SCOPE_LINKLOCAL)
+				continue;
 		}
 
 		batadv_mcast_mla_br_addr_cpy(mcast_addr, &br_ip_entry->addr);
@@ -654,19 +770,23 @@ 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]",
+	sprintf(str_old_flags, "[%c%c%c%s%s]",
 		(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_ALL_IPV6) ? '6' : '.',
+		(old_flags & BATADV_MCAST_WANT_ALL_RTR4) ? "R4" : ". ",
+		(old_flags & BATADV_MCAST_WANT_ALL_RTR6) ? "R6" : ". ");
 
 	batadv_dbg(BATADV_DBG_MCAST, bat_priv,
-		   "Changing multicast flags from '%s' to '[%c%c%c]'\n",
+		   "Changing multicast flags from '%s' to '[%c%c%c%s%s]'\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_ALL_IPV6) ? '6' : '.',
+		   (flags & BATADV_MCAST_WANT_ALL_RTR4) ? "R4" : ". ",
+		   (flags & BATADV_MCAST_WANT_ALL_RTR6) ? "R6" : ". ");
 }
 
 /**
@@ -689,7 +809,12 @@ batadv_mcast_mla_flags_update(struct batadv_priv *bat_priv,
 	batadv_mcast_bridge_log(bat_priv, flags);
 	batadv_mcast_flags_log(bat_priv, flags->tvlv_flags);
 
+	/* toggle WANT_ALL_RTR flags as they are sent flipped on the
+	 * wire for backwards compatibility
+	 */
 	mcast_data.flags = flags->tvlv_flags;
+	mcast_data.flags ^= BATADV_MCAST_WANT_ALL_RTR4;
+	mcast_data.flags ^= BATADV_MCAST_WANT_ALL_RTR6;
 	memset(mcast_data.reserved, 0, sizeof(mcast_data.reserved));
 
 	batadv_tvlv_container_register(bat_priv, BATADV_TVLV_MCAST, 2,
@@ -1458,6 +1583,132 @@ static void batadv_mcast_want_ipv6_update(struct batadv_priv *bat_priv,
 	}
 }
 
+/**
+ * batadv_mcast_want_rtr4_update() - update want-all-rtr4 counter and list
+ * @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_WANT_ALL_RTR4 flag of this originator, orig, has
+ * toggled then this method updates counter and list accordingly.
+ *
+ * Caller needs to hold orig->mcast_handler_lock.
+ */
+static void batadv_mcast_want_rtr4_update(struct batadv_priv *bat_priv,
+					  struct batadv_orig_node *orig,
+					  u8 mcast_flags)
+{
+	struct hlist_node *node = &orig->mcast_want_all_rtr4_node;
+	struct hlist_head *head = &bat_priv->mcast.want_all_rtr4_list;
+
+	lockdep_assert_held(&orig->mcast_handler_lock);
+
+	/* switched from flag unset to set */
+	if (mcast_flags & BATADV_MCAST_WANT_ALL_RTR4 &&
+	    !(orig->mcast_flags & BATADV_MCAST_WANT_ALL_RTR4)) {
+		atomic_inc(&bat_priv->mcast.num_want_all_rtr4);
+
+		spin_lock_bh(&bat_priv->mcast.want_lists_lock);
+		/* flag checks above + mcast_handler_lock prevents this */
+		WARN_ON(!hlist_unhashed(node));
+
+		hlist_add_head_rcu(node, head);
+		spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
+	/* switched from flag set to unset */
+	} else if (!(mcast_flags & BATADV_MCAST_WANT_ALL_RTR4) &&
+		   orig->mcast_flags & BATADV_MCAST_WANT_ALL_RTR4) {
+		atomic_dec(&bat_priv->mcast.num_want_all_rtr4);
+
+		spin_lock_bh(&bat_priv->mcast.want_lists_lock);
+		/* flag checks above + mcast_handler_lock prevents this */
+		WARN_ON(hlist_unhashed(node));
+
+		hlist_del_init_rcu(node);
+		spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
+	}
+}
+
+/**
+ * batadv_mcast_want_rtr6_update() - update want-all-rtr6 counter and list
+ * @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_WANT_ALL_RTR6 flag of this originator, orig, has
+ * toggled then this method updates counter and list accordingly.
+ *
+ * Caller needs to hold orig->mcast_handler_lock.
+ */
+static void batadv_mcast_want_rtr6_update(struct batadv_priv *bat_priv,
+					  struct batadv_orig_node *orig,
+					  u8 mcast_flags)
+{
+	struct hlist_node *node = &orig->mcast_want_all_rtr6_node;
+	struct hlist_head *head = &bat_priv->mcast.want_all_rtr6_list;
+
+	lockdep_assert_held(&orig->mcast_handler_lock);
+
+	/* switched from flag unset to set */
+	if (mcast_flags & BATADV_MCAST_WANT_ALL_RTR6 &&
+	    !(orig->mcast_flags & BATADV_MCAST_WANT_ALL_RTR6)) {
+		atomic_inc(&bat_priv->mcast.num_want_all_rtr6);
+
+		spin_lock_bh(&bat_priv->mcast.want_lists_lock);
+		/* flag checks above + mcast_handler_lock prevents this */
+		WARN_ON(!hlist_unhashed(node));
+
+		hlist_add_head_rcu(node, head);
+		spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
+	/* switched from flag set to unset */
+	} else if (!(mcast_flags & BATADV_MCAST_WANT_ALL_RTR6) &&
+		   orig->mcast_flags & BATADV_MCAST_WANT_ALL_RTR6) {
+		atomic_dec(&bat_priv->mcast.num_want_all_rtr6);
+
+		spin_lock_bh(&bat_priv->mcast.want_lists_lock);
+		/* flag checks above + mcast_handler_lock prevents this */
+		WARN_ON(hlist_unhashed(node));
+
+		hlist_del_init_rcu(node);
+		spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
+	}
+}
+
+/**
+ * batadv_mcast_tvlv_flags_get() - get multicast flags from an OGM TVLV
+ * @enabled: whether the originator has multicast TVLV support enabled
+ * @tvlv_value: tvlv buffer containing the multicast flags
+ * @tvlv_value_len: tvlv buffer length
+ *
+ * Return: multicast flags for the given tvlv buffer
+ */
+static u8
+batadv_mcast_tvlv_flags_get(bool enabled, void *tvlv_value, u16 tvlv_value_len)
+{
+	u8 mcast_flags = BATADV_NO_FLAGS;
+
+	if (enabled && tvlv_value && tvlv_value_len >= sizeof(mcast_flags))
+		mcast_flags = *(u8 *)tvlv_value;
+
+	if (!enabled) {
+		mcast_flags |= BATADV_MCAST_WANT_ALL_IPV4;
+		mcast_flags |= BATADV_MCAST_WANT_ALL_IPV6;
+	}
+
+	/* unflip: WANT_ALL_RTR flags are sent flipped on the wire for
+	 * backwards compatibiltiy
+	 */
+	mcast_flags ^= BATADV_MCAST_WANT_ALL_RTR4 | BATADV_MCAST_WANT_ALL_RTR6;
+
+	/* remove redundant flags to avoid sending duplicate packets later */
+	if (mcast_flags & BATADV_MCAST_WANT_ALL_IPV4)
+		mcast_flags &= ~BATADV_MCAST_WANT_ALL_RTR4;
+
+	if (mcast_flags & BATADV_MCAST_WANT_ALL_IPV6)
+		mcast_flags &= ~BATADV_MCAST_WANT_ALL_RTR6;
+
+	return mcast_flags;
+}
+
 /**
  * batadv_mcast_tvlv_ogm_handler() - process incoming multicast tvlv container
  * @bat_priv: the bat priv with all the soft interface information
@@ -1473,16 +1724,10 @@ static void batadv_mcast_tvlv_ogm_handler(struct batadv_priv *bat_priv,
 					  u16 tvlv_value_len)
 {
 	bool orig_mcast_enabled = !(flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
-	u8 mcast_flags = BATADV_NO_FLAGS;
+	u8 mcast_flags;
 
-	if (orig_mcast_enabled && tvlv_value &&
-	    tvlv_value_len >= sizeof(mcast_flags))
-		mcast_flags = *(u8 *)tvlv_value;
-
-	if (!orig_mcast_enabled) {
-		mcast_flags |= BATADV_MCAST_WANT_ALL_IPV4;
-		mcast_flags |= BATADV_MCAST_WANT_ALL_IPV6;
-	}
+	mcast_flags = batadv_mcast_tvlv_flags_get(orig_mcast_enabled,
+						  tvlv_value, tvlv_value_len);
 
 	spin_lock_bh(&orig->mcast_handler_lock);
 
@@ -1499,6 +1744,8 @@ static void batadv_mcast_tvlv_ogm_handler(struct batadv_priv *bat_priv,
 	batadv_mcast_want_unsnoop_update(bat_priv, orig, mcast_flags);
 	batadv_mcast_want_ipv4_update(bat_priv, orig, mcast_flags);
 	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);
 
 	orig->mcast_flags = mcast_flags;
 	spin_unlock_bh(&orig->mcast_handler_lock);
@@ -1548,10 +1795,12 @@ static void batadv_mcast_flags_print_header(struct batadv_priv *bat_priv,
 		shadowing6 = '?';
 	}
 
-	seq_printf(seq, "Multicast flags (own flags: [%c%c%c])\n",
+	seq_printf(seq, "Multicast flags (own flags: [%c%c%c%s%s])\n",
 		   (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_ALL_IPV6) ? '6' : '.',
+		   (flags & BATADV_MCAST_WANT_ALL_RTR4) ? "R4" : ". ",
+		   (flags & BATADV_MCAST_WANT_ALL_RTR6) ? "R6" : ". ");
 	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);
@@ -1605,13 +1854,17 @@ int batadv_mcast_flags_seq_print_text(struct seq_file *seq, void *offset)
 
 			flags = orig_node->mcast_flags;
 
-			seq_printf(seq, "%pM [%c%c%c]\n", orig_node->orig,
+			seq_printf(seq, "%pM [%c%c%c%s%s]\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' : '.');
+				   ? '6' : '.',
+				   (flags & BATADV_MCAST_WANT_ALL_RTR4)
+				   ? "R4" : ". ",
+				   (flags & BATADV_MCAST_WANT_ALL_RTR6)
+				   ? "R6" : ". ");
 		}
 		rcu_read_unlock();
 	}
@@ -1885,6 +2138,8 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig)
 	batadv_mcast_want_unsnoop_update(bat_priv, orig, BATADV_NO_FLAGS);
 	batadv_mcast_want_ipv4_update(bat_priv, orig, BATADV_NO_FLAGS);
 	batadv_mcast_want_ipv6_update(bat_priv, orig, BATADV_NO_FLAGS);
+	batadv_mcast_want_rtr4_update(bat_priv, orig, BATADV_NO_FLAGS);
+	batadv_mcast_want_rtr6_update(bat_priv, orig, BATADV_NO_FLAGS);
 
 	spin_unlock_bh(&orig->mcast_handler_lock);
 }
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 3212cfc9..e1bb6037 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -402,6 +402,17 @@ struct batadv_orig_node {
 	 *  list
 	 */
 	struct hlist_node mcast_want_all_ipv6_node;
+
+	/**
+	 * @mcast_want_all_rtr4_node: a list node for the mcast.want_all_rtr4
+	 *  list
+	 */
+	struct hlist_node mcast_want_all_rtr4_node;
+	/**
+	 * @mcast_want_all_rtr6_node: a list node for the mcast.want_all_rtr6
+	 *  list
+	 */
+	struct hlist_node mcast_want_all_rtr6_node;
 #endif
 
 	/** @capabilities: announced capabilities of this originator */
@@ -1216,6 +1227,18 @@ struct batadv_priv_mcast {
 	 */
 	struct hlist_head want_all_ipv6_list;
 
+	/**
+	 * @want_all_rtr4_list: a list of orig_nodes wanting all routeable IPv4
+	 *  multicast traffic
+	 */
+	struct hlist_head want_all_rtr4_list;
+
+	/**
+	 * @want_all_rtr6_list: a list of orig_nodes wanting all routeable IPv6
+	 *  multicast traffic
+	 */
+	struct hlist_head want_all_rtr6_list;
+
 	/**
 	 * @mla_flags: flags for the querier, bridge and tvlv state
 	 */
@@ -1238,6 +1261,12 @@ struct batadv_priv_mcast {
 	/** @num_want_all_ipv6: counter for items in want_all_ipv6_list */
 	atomic_t num_want_all_ipv6;
 
+	/** @num_want_all_rtr4: counter for items in want_all_rtr4_list */
+	atomic_t num_want_all_rtr4;
+
+	/** @num_want_all_rtr6: counter for items in want_all_rtr6_list */
+	atomic_t num_want_all_rtr6;
+
 	/**
 	 * @want_lists_lock: lock for protecting modifications to mcasts
 	 *  want_all_{unsnoopables,ipv4,ipv6}_list (traversals are rcu-locked)
-- 
2.20.1

[PATCH v2 2/2] batman-adv: mcast: apply optimizations for routeable packets, too

[Linus Lüssing]

Now that we not only track the presence of multicast listeners but also
multicast routers we can safely apply group-aware multicast-to-unicast
forwarding to packets with a destination address of scope greater than
link-local as well.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 net/batman-adv/multicast.c | 259 ++++++++++++++++++++++++++++++++++---
 1 file changed, 241 insertions(+), 18 deletions(-)

diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index a87fb596..bf893d65 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -916,6 +916,7 @@ static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb)
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the IPv4 packet to check
  * @is_unsnoopable: stores whether the destination is snoopable
+ * @is_routeable: stores whether the destination is routeable
  *
  * Checks whether the given IPv4 packet has the potential to be forwarded with a
  * mode more optimal than classic flooding.
@@ -925,7 +926,8 @@ static bool batadv_mcast_is_report_ipv4(struct sk_buff *skb)
  */
 static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
 					     struct sk_buff *skb,
-					     bool *is_unsnoopable)
+					     bool *is_unsnoopable,
+					     int *is_routeable)
 {
 	struct iphdr *iphdr;
 
@@ -938,16 +940,13 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
 
 	iphdr = ip_hdr(skb);
 
-	/* TODO: Implement Multicast Router Discovery (RFC4286),
-	 * then allow scope > link local, too
-	 */
-	if (!ipv4_is_local_multicast(iphdr->daddr))
-		return -EINVAL;
-
 	/* link-local multicast listeners behind a bridge are
 	 * not snoopable (see RFC4541, section 2.1.2.2)
 	 */
-	*is_unsnoopable = true;
+	if (ipv4_is_local_multicast(iphdr->daddr))
+		*is_unsnoopable = true;
+	else
+		*is_routeable = ETH_P_IP;
 
 	return 0;
 }
@@ -982,6 +981,7 @@ static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb)
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the IPv6 packet to check
  * @is_unsnoopable: stores whether the destination is snoopable
+ * @is_routeable: stores whether the destination is routeable
  *
  * Checks whether the given IPv6 packet has the potential to be forwarded with a
  * mode more optimal than classic flooding.
@@ -990,7 +990,8 @@ static bool batadv_mcast_is_report_ipv6(struct sk_buff *skb)
  */
 static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 					     struct sk_buff *skb,
-					     bool *is_unsnoopable)
+					     bool *is_unsnoopable,
+					     int *is_routeable)
 {
 	struct ipv6hdr *ip6hdr;
 
@@ -1003,10 +1004,7 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 
 	ip6hdr = ipv6_hdr(skb);
 
-	/* TODO: Implement Multicast Router Discovery (RFC4286),
-	 * then allow scope > link local, too
-	 */
-	if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) != IPV6_ADDR_SCOPE_LINKLOCAL)
+	if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) < IPV6_ADDR_SCOPE_LINKLOCAL)
 		return -EINVAL;
 
 	/* link-local-all-nodes multicast listeners behind a bridge are
@@ -1014,6 +1012,8 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 	 */
 	if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr))
 		*is_unsnoopable = true;
+	else if (IPV6_ADDR_MC_SCOPE(&ip6hdr->daddr) > IPV6_ADDR_SCOPE_LINKLOCAL)
+		*is_routeable = ETH_P_IPV6;
 
 	return 0;
 }
@@ -1023,6 +1023,7 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the multicast frame to check
  * @is_unsnoopable: stores whether the destination is snoopable
+ * @is_routeable: stores whether the destination is routeable
  *
  * Checks whether the given multicast ethernet frame has the potential to be
  * forwarded with a mode more optimal than classic flooding.
@@ -1031,7 +1032,8 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
  */
 static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
 					struct sk_buff *skb,
-					bool *is_unsnoopable)
+					bool *is_unsnoopable,
+					int *is_routeable)
 {
 	struct ethhdr *ethhdr = eth_hdr(skb);
 
@@ -1041,13 +1043,15 @@ static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
 	switch (ntohs(ethhdr->h_proto)) {
 	case ETH_P_IP:
 		return batadv_mcast_forw_mode_check_ipv4(bat_priv, skb,
-							 is_unsnoopable);
+							 is_unsnoopable,
+							 is_routeable);
 	case ETH_P_IPV6:
 		if (!IS_ENABLED(CONFIG_IPV6))
 			return -EINVAL;
 
 		return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb,
-							 is_unsnoopable);
+							 is_unsnoopable,
+							 is_routeable);
 	default:
 		return -EINVAL;
 	}
@@ -1077,6 +1081,29 @@ static int batadv_mcast_forw_want_all_ip_count(struct batadv_priv *bat_priv,
 	}
 }
 
+/**
+ * batadv_mcast_forw_rtr_count() - count nodes with a multicast router
+ * @bat_priv: the bat priv with all the soft interface information
+ * @protocol: the ethernet protocol type to count multicast routers for
+ *
+ * Return: the number of nodes which want all routeable IPv4 multicast traffic
+ * if the protocol is ETH_P_IP or the number of nodes which want all routeable
+ * IPv6 traffic if the protocol is ETH_P_IPV6. Otherwise returns 0.
+ */
+
+static int batadv_mcast_forw_rtr_count(struct batadv_priv *bat_priv,
+				       int protocol)
+{
+	switch (protocol) {
+	case ETH_P_IP:
+		return atomic_read(&bat_priv->mcast.num_want_all_rtr4);
+	case ETH_P_IPV6:
+		return atomic_read(&bat_priv->mcast.num_want_all_rtr6);
+	default:
+		return 0;
+	}
+}
+
 /**
  * batadv_mcast_forw_tt_node_get() - get a multicast tt node
  * @bat_priv: the bat priv with all the soft interface information
@@ -1198,6 +1225,84 @@ batadv_mcast_forw_unsnoop_node_get(struct batadv_priv *bat_priv)
 	return orig_node;
 }
 
+/**
+ * batadv_mcast_forw_rtr4_node_get() - get a node with an ipv4 mcast router flag
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Return: an orig_node which has the BATADV_MCAST_WANT_ALL_RTR4 flag set and
+ * increases its refcount.
+ */
+static struct batadv_orig_node *
+batadv_mcast_forw_rtr4_node_get(struct batadv_priv *bat_priv)
+{
+	struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(tmp_orig_node,
+				 &bat_priv->mcast.want_all_rtr4_list,
+				 mcast_want_all_rtr4_node) {
+		if (!kref_get_unless_zero(&tmp_orig_node->refcount))
+			continue;
+
+		orig_node = tmp_orig_node;
+		break;
+	}
+	rcu_read_unlock();
+
+	return orig_node;
+}
+
+/**
+ * batadv_mcast_forw_rtr6_node_get() - get a node with an ipv6 mcast router flag
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Return: an orig_node which has the BATADV_MCAST_WANT_ALL_RTR6 flag set
+ * and increases its refcount.
+ */
+static struct batadv_orig_node *
+batadv_mcast_forw_rtr6_node_get(struct batadv_priv *bat_priv)
+{
+	struct batadv_orig_node *tmp_orig_node, *orig_node = NULL;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(tmp_orig_node,
+				 &bat_priv->mcast.want_all_rtr6_list,
+				 mcast_want_all_rtr6_node) {
+		if (!kref_get_unless_zero(&tmp_orig_node->refcount))
+			continue;
+
+		orig_node = tmp_orig_node;
+		break;
+	}
+	rcu_read_unlock();
+
+	return orig_node;
+}
+
+/**
+ * batadv_mcast_forw_rtr_node_get() - get a node with an ipv4/ipv6 router flag
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ethhdr: an ethernet header to determine the protocol family from
+ *
+ * Return: an orig_node which has the BATADV_MCAST_WANT_ALL_RTR4 or
+ * BATADV_MCAST_WANT_ALL_RTR6 flag, depending on the provided ethhdr, set and
+ * increases its refcount.
+ */
+static struct batadv_orig_node *
+batadv_mcast_forw_rtr_node_get(struct batadv_priv *bat_priv,
+			       struct ethhdr *ethhdr)
+{
+	switch (ntohs(ethhdr->h_proto)) {
+	case ETH_P_IP:
+		return batadv_mcast_forw_rtr4_node_get(bat_priv);
+	case ETH_P_IPV6:
+		return batadv_mcast_forw_rtr6_node_get(bat_priv);
+	default:
+		/* we shouldn't be here... */
+		return NULL;
+	}
+}
+
 /**
  * batadv_mcast_forw_mode() - check on how to forward a multicast packet
  * @bat_priv: the bat priv with all the soft interface information
@@ -1216,8 +1321,11 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 	bool is_unsnoopable = false;
 	unsigned int mcast_fanout;
 	struct ethhdr *ethhdr;
+	int is_routeable = 0;
+	int rtr_count = 0;
 
-	ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable);
+	ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable,
+					   &is_routeable);
 	if (ret == -ENOMEM)
 		return BATADV_FORW_NONE;
 	else if (ret < 0)
@@ -1230,8 +1338,9 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 	ip_count = batadv_mcast_forw_want_all_ip_count(bat_priv, ethhdr);
 	unsnoop_count = !is_unsnoopable ? 0 :
 			atomic_read(&bat_priv->mcast.num_want_all_unsnoopables);
+	rtr_count = batadv_mcast_forw_rtr_count(bat_priv, is_routeable);
 
-	total_count = tt_count + ip_count + unsnoop_count;
+	total_count = tt_count + ip_count + unsnoop_count + rtr_count;
 
 	switch (total_count) {
 	case 1:
@@ -1241,6 +1350,9 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 			*orig = batadv_mcast_forw_ip_node_get(bat_priv, ethhdr);
 		else if (unsnoop_count)
 			*orig = batadv_mcast_forw_unsnoop_node_get(bat_priv);
+		else if (rtr_count)
+			*orig = batadv_mcast_forw_rtr_node_get(bat_priv,
+							       ethhdr);
 
 		if (*orig)
 			return BATADV_FORW_SINGLE;
@@ -1411,6 +1523,111 @@ batadv_mcast_forw_want_all(struct batadv_priv *bat_priv,
 	}
 }
 
+/**
+ * batadv_mcast_forw_want_all_rtr4() - forward to nodes with want-all-rtr4
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to transmit
+ * @vid: the vlan identifier
+ *
+ * Sends copies of a frame with multicast destination to any node with a
+ * BATADV_MCAST_WANT_ALL_RTR4 flag set. A transmission is performed via a
+ * batman-adv unicast packet for each such destination node.
+ *
+ * Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
+ * otherwise.
+ */
+static int
+batadv_mcast_forw_want_all_rtr4(struct batadv_priv *bat_priv,
+				struct sk_buff *skb, unsigned short vid)
+{
+	struct batadv_orig_node *orig_node;
+	int ret = NET_XMIT_SUCCESS;
+	struct sk_buff *newskb;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(orig_node,
+				 &bat_priv->mcast.want_all_rtr4_list,
+				 mcast_want_all_rtr4_node) {
+		newskb = skb_copy(skb, GFP_ATOMIC);
+		if (!newskb) {
+			ret = NET_XMIT_DROP;
+			break;
+		}
+
+		batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
+					orig_node, vid);
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+/**
+ * batadv_mcast_forw_want_all_rtr6() - forward to nodes with want-all-rtr6
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: The multicast packet to transmit
+ * @vid: the vlan identifier
+ *
+ * Sends copies of a frame with multicast destination to any node with a
+ * BATADV_MCAST_WANT_ALL_RTR6 flag set. A transmission is performed via a
+ * batman-adv unicast packet for each such destination node.
+ *
+ * Return: NET_XMIT_DROP on memory allocation failure, NET_XMIT_SUCCESS
+ * otherwise.
+ */
+static int
+batadv_mcast_forw_want_all_rtr6(struct batadv_priv *bat_priv,
+				struct sk_buff *skb, unsigned short vid)
+{
+	struct batadv_orig_node *orig_node;
+	int ret = NET_XMIT_SUCCESS;
+	struct sk_buff *newskb;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(orig_node,
+				 &bat_priv->mcast.want_all_rtr6_list,
+				 mcast_want_all_rtr6_node) {
+		newskb = skb_copy(skb, GFP_ATOMIC);
+		if (!newskb) {
+			ret = NET_XMIT_DROP;
+			break;
+		}
+
+		batadv_send_skb_unicast(bat_priv, newskb, BATADV_UNICAST, 0,
+					orig_node, vid);
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+/**
+ * batadv_mcast_forw_want_rtr() - forward packet to nodes in a want-all-rtr list
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the multicast packet to transmit
+ * @vid: the vlan identifier
+ *
+ * Sends copies of a frame with multicast destination to any node with a
+ * BATADV_MCAST_WANT_ALL_RTR4 or BATADV_MCAST_WANT_ALL_RTR6 flag set. A
+ * transmission is performed via a batman-adv unicast packet for each such
+ * destination node.
+ *
+ * Return: NET_XMIT_DROP on memory allocation failure or if the protocol family
+ * is neither IPv4 nor IPv6. NET_XMIT_SUCCESS otherwise.
+ */
+static int
+batadv_mcast_forw_want_rtr(struct batadv_priv *bat_priv,
+			   struct sk_buff *skb, unsigned short vid)
+{
+	switch (ntohs(eth_hdr(skb)->h_proto)) {
+	case ETH_P_IP:
+		return batadv_mcast_forw_want_all_rtr4(bat_priv, skb, vid);
+	case ETH_P_IPV6:
+		return batadv_mcast_forw_want_all_rtr6(bat_priv, skb, vid);
+	default:
+		/* we shouldn't be here... */
+		return NET_XMIT_DROP;
+	}
+}
+
 /**
  * batadv_mcast_forw_send() - send packet to any detected multicast recpient
  * @bat_priv: the bat priv with all the soft interface information
@@ -1444,6 +1661,12 @@ int batadv_mcast_forw_send(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		return ret;
 	}
 
+	ret = batadv_mcast_forw_want_rtr(bat_priv, skb, vid);
+	if (ret != NET_XMIT_SUCCESS) {
+		kfree_skb(skb);
+		return ret;
+	}
+
 	consume_skb(skb);
 	return ret;
 }
-- 
2.20.1

Re: [PATCH v2 1/2] batman-adv: mcast: detect, distribute and maintain multicast router presence

[Sven Eckelmann]

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On Tuesday, 7 May 2019 06:20:03 CEST Linus Lüssing wrote:
> +static u8 batadv_mcast_mla_rtr_flags_softif_get(struct batadv_priv *bat_priv,
> +                                               struct net_device *bridge)
> +{
> +       struct net_device *dev = bridge ? bridge : bat_priv->soft_iface;
> +       u8 flags = BATADV_NO_FLAGS;
> +       struct inet6_dev *in6_dev;
> +       struct in_device *in_dev;
> +
> +       rcu_read_lock();
> +       in_dev = __in_dev_get_rcu(dev);
> +       if (in_dev && IN_DEV_MFORWARD(in_dev))
> +               flags |= BATADV_MCAST_WANT_ALL_RTR4;
> +
> +       in6_dev = __in6_dev_get(dev);
> +       if (in6_dev && in6_dev->cnf.mc_forwarding)
> +               flags |= BATADV_MCAST_WANT_ALL_RTR6;
> +       rcu_read_unlock();
> +
> +       return flags;
> +}

Fails to build on Linux 5.1 with:

/home/sven/tmp/qemu-batman/batman-adv/net/batman-adv/multicast.c: In function 'batadv_mcast_mla_rtr_flags_softif_get':
/home/sven/tmp/qemu-batman/batman-adv/net/batman-adv/multicast.c:130:30: error: 'struct ipv6_devconf' has no member named 'mc_forwarding'; did you mean 'forwarding'?
  if (in6_dev && in6_dev->cnf.mc_forwarding)
                              ^~~~~~~~~~~~~
                              forwarding

See 
https://git.open-mesh.org/build_test.git/blob/HEAD:/generate_linux_headers.sh 
for the configuration.

Kind regards,
	Sven

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