[B.A.T.M.A.N.] [PATCHv6 0/3] batman-adv: Unicasting multicast reports to querier-node only

[B.A.T.M.A.N.] [PATCHv6 0/3] batman-adv: Unicasting multicast reports to querier-node only

[Linus Lüssing]

The last round of multicast patches send to the batman-adv mailinglist
to add support for the multicast optimizations in bridged scenarios, too,
unfortunately had one major conceptual flaw: It could lead to packet loss.
It's not sufficient to have the unicasting of reports implemented on
bridge-nodes only. Nodes without bridges need to treat reports the same
way.

The issue is described in detail here:

https://www.open-mesh.org/projects/batman-adv/wiki/Multicast-optimizations-listener-reports


Cheers, Linus

-----

Changelog:
v6:
 * compat: copied copyright headers from original upstream c files
 * compat: unified ordering in compat c files:
   -> copyright header, then includes, then kernel specific functions
v5:
 * Removed RFC tag: Needed exports got merged to net-next and are going to
   be available with Linux 4.2
 * Redid compat solution - now fully backwards compatible down to 2.6.33
v4:
 * excluded bridge part from this patchset, they should
   hopefully be added to net-next soon
 * Added a compat solution (PATCH 3/3)
 * Removed Kconfig-depends as by David's suggestion the needed parsing
   functions for MLD are going to be forced built-ins even if IPv6 is
   going to be built as a module
 * Removed unused variable 'int ret' in batadv_mcast_is_report_ipv6()
 * Adjusted to new folder structure
v3:
 * Adding Kconfig-depends and #if's
   (so basically adding similar dependancy constraints as the bridge code
    has, except that there are no depends if batman-adv gets compiled without
    multicast optimizations)
   -> the case of IPv6=M and batman-adv=y is still impossible if multicast
      optimizations are enabled; but I don't see the practical demand for that
      either - people who use IPv6 as a module will probably also want to
      use batman-adv as a module
v2:
 * various bugfixes (now runtime tested, too - should(tm) work)
 * added netdev+bridge mailinglists

[B.A.T.M.A.N.] [PATCHv6 1/3] batman-adv: Forward IGMP/MLD reports to selected querier (only)

[Linus Lüssing]

With this patch IGMP or MLD reports are only forwarded to the selected
IGMP/MLD querier as RFC4541 suggests. This is necessary to avoid
multicast packet loss in bridged scenarios later:

An IGMPv2/MLDv1 querier does not actively join the multicast group the
reports are sent to. Because of this, this leads to snooping
bridges/switches not being able to learn of multicast listeners in the
mesh and wrongly shutting down ports for multicast traffic to the mesh.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 net/batman-adv/main.h           |    4 +-
 net/batman-adv/multicast.c      |  257 ++++++++++++++++++++++++++++++++++++++-
 net/batman-adv/multicast.h      |    8 ++
 net/batman-adv/soft-interface.c |   11 ++
 net/batman-adv/types.h          |   14 +++
 5 files changed, 287 insertions(+), 7 deletions(-)

diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index 41d27c7..2832cf9 100644
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -219,6 +219,7 @@ __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr);
  * @BATADV_DBG_BLA: bridge loop avoidance messages
  * @BATADV_DBG_DAT: ARP snooping and DAT related messages
  * @BATADV_DBG_NC: network coding related messages
+ * @BATADV_DBG_MCAST: multicast related messages
  * @BATADV_DBG_ALL: the union of all the above log levels
  */
 enum batadv_dbg_level {
@@ -228,7 +229,8 @@ enum batadv_dbg_level {
 	BATADV_DBG_BLA    = BIT(3),
 	BATADV_DBG_DAT    = BIT(4),
 	BATADV_DBG_NC	  = BIT(5),
-	BATADV_DBG_ALL    = 63,
+	BATADV_DBG_MCAST  = BIT(6),
+	BATADV_DBG_ALL    = 127,
 };
 
 #ifdef CONFIG_BATMAN_ADV_DEBUG
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 7aa480b..72d561c 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -24,6 +24,7 @@
 #include <linux/etherdevice.h>
 #include <linux/fs.h>
 #include <linux/if_ether.h>
+#include <linux/igmp.h>
 #include <linux/in6.h>
 #include <linux/in.h>
 #include <linux/ip.h>
@@ -40,6 +41,7 @@
 #include <linux/types.h>
 #include <net/addrconf.h>
 #include <net/ipv6.h>
+#include <net/mld.h>
 
 #include "packet.h"
 #include "translation-table.h"
@@ -270,10 +272,76 @@ out:
 }
 
 /**
+ * batadv_mcast_is_report_ipv4 - check for IGMP reports (and queries)
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the ethernet frame destined for the mesh
+ * @orig: if IGMP report: to be set to the querier to forward the skb to
+ *
+ * Checks whether the given frame is an IGMP report and if so sets the
+ * orig pointer to the originator of the selected IGMP querier if one exists
+ * and returns true. Otherwise returns false.
+ *
+ * If the packet is a general IGMP query instead then we delete the memorized,
+ * foreign IGMP querier (if one exists): We became the selected querier and
+ * therefore do not need to forward reports into the mesh.
+ *
+ * This call might reallocate skb data.
+ */
+static bool batadv_mcast_is_report_ipv4(struct batadv_priv *bat_priv,
+					struct sk_buff *skb,
+					struct batadv_orig_node **orig)
+{
+	struct batadv_mcast_querier_state *querier;
+	struct batadv_orig_node *orig_node;
+
+	if (ip_mc_check_igmp(skb, NULL) < 0)
+		return false;
+
+	querier = &bat_priv->mcast.querier_ipv4;
+
+	switch (igmp_hdr(skb)->type) {
+	case IGMP_HOST_MEMBERSHIP_REPORT:
+	case IGMPV2_HOST_MEMBERSHIP_REPORT:
+	case IGMPV3_HOST_MEMBERSHIP_REPORT:
+		rcu_read_lock();
+		orig_node = rcu_dereference(querier->orig);
+		if (orig_node && atomic_inc_not_zero(&orig_node->refcount)) {
+			/* TODO: include multicast routers via MRD (RFC4286) */
+			batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+				   "Redirecting IGMP Report to %pM\n",
+				   orig_node->orig);
+			*orig = orig_node;
+		}
+		rcu_read_unlock();
+
+		return true;
+	case IGMP_HOST_MEMBERSHIP_QUERY:
+		/* RFC4541, section 2.1.1.1.b) says:
+		 * ignore general queries from 0.0.0.0
+		 */
+		if (!ip_hdr(skb)->saddr || igmp_hdr(skb)->group)
+			break;
+
+		spin_lock_bh(&querier->orig_lock);
+		orig_node = rcu_dereference(querier->orig);
+		if (orig_node)
+			rcu_assign_pointer(querier->orig, NULL);
+		spin_unlock_bh(&querier->orig_lock);
+
+		batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+			   "Snooped own IGMP Query\n");
+		break;
+	}
+
+	return false;
+}
+
+/**
  * batadv_mcast_forw_mode_check_ipv4 - check for optimized forwarding potential
  * @bat_priv: the bat priv with all the soft interface information
  * @skb: the IPv4 packet to check
  * @is_unsnoopable: stores whether the destination is snoopable
+ * @orig: for IGMP reports: to be set to the querier to forward the skb to
  *
  * Checks whether the given IPv4 packet has the potential to be forwarded with a
  * mode more optimal than classic flooding.
@@ -283,7 +351,8 @@ out:
  */
 static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
 					     struct sk_buff *skb,
-					     bool *is_unsnoopable)
+					     bool *is_unsnoopable,
+					     struct batadv_orig_node **orig)
 {
 	struct iphdr *iphdr;
 
@@ -291,6 +360,9 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
 	if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*iphdr)))
 		return -ENOMEM;
 
+	if (batadv_mcast_is_report_ipv4(bat_priv, skb, orig))
+		return 0;
+
 	iphdr = ip_hdr(skb);
 
 	/* TODO: Implement Multicast Router Discovery (RFC4286),
@@ -307,11 +379,73 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
 	return 0;
 }
 
+#if IS_ENABLED(CONFIG_IPV6)
+/**
+ * batadv_mcast_is_report_ipv6 - check for MLD reports (and queries)
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: the ethernet frame destined for the mesh
+ * @orig: if MLD report: to be set to the querier to forward the skb to
+ *
+ * Checks whether the given frame is an MLD report and if so sets the
+ * orig pointer to the originator of the selected MLD querier if one exists
+ * and returns true. Otherwise returns false.
+ *
+ * If the packet is a general MLD query instead then we delete the memorized,
+ * foreign MLD querier (if one exists): We became the selected querier and
+ * therefore do not need to forward reports into the mesh.
+ *
+ * This call might reallocate skb data.
+ */
+static bool batadv_mcast_is_report_ipv6(struct batadv_priv *bat_priv,
+					struct sk_buff *skb,
+					struct batadv_orig_node **orig)
+{
+	struct mld_msg *mld;
+	struct batadv_mcast_querier_state *querier;
+	struct batadv_orig_node *orig_node;
+
+	if (ipv6_mc_check_mld(skb, NULL) < 0)
+		return false;
+
+	querier = &bat_priv->mcast.querier_ipv6;
+	mld = (struct mld_msg *)icmp6_hdr(skb);
+
+	switch (mld->mld_type) {
+	case ICMPV6_MGM_REPORT:
+	case ICMPV6_MLD2_REPORT:
+		rcu_read_lock();
+		orig_node = rcu_dereference(querier->orig);
+		if (orig_node && atomic_inc_not_zero(&orig_node->refcount)) {
+			/* TODO: include multicast routers via MRD (RFC4286) */
+			batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+				   "Redirecting MLD Report to %pM\n",
+				   orig_node->orig);
+			*orig = orig_node;
+		}
+		rcu_read_unlock();
+
+		return true;
+	case ICMPV6_MGM_QUERY:
+		spin_lock_bh(&querier->orig_lock);
+		orig_node = rcu_dereference(querier->orig);
+		if (orig_node)
+			rcu_assign_pointer(querier->orig, NULL);
+		spin_unlock_bh(&querier->orig_lock);
+
+		batadv_dbg(BATADV_DBG_MCAST, bat_priv,
+			   "Snooped own MLD Query\n");
+		break;
+	}
+
+	return false;
+}
+
 /**
  * batadv_mcast_forw_mode_check_ipv6 - check for optimized forwarding potential
  * @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
+ * @orig: for MLD reports: to be set to the querier to forward the skb to
  *
  * Checks whether the given IPv6 packet has the potential to be forwarded with a
  * mode more optimal than classic flooding.
@@ -321,7 +455,8 @@ static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
  */
 static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 					     struct sk_buff *skb,
-					     bool *is_unsnoopable)
+					     bool *is_unsnoopable,
+					     struct batadv_orig_node **orig)
 {
 	struct ipv6hdr *ip6hdr;
 
@@ -329,6 +464,9 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 	if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*ip6hdr)))
 		return -ENOMEM;
 
+	if (batadv_mcast_is_report_ipv6(bat_priv, skb, orig))
+		return 0;
+
 	ip6hdr = ipv6_hdr(skb);
 
 	/* TODO: Implement Multicast Router Discovery (RFC4286),
@@ -345,6 +483,7 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
 
 	return 0;
 }
+#endif
 
 /**
  * batadv_mcast_forw_mode_check - check for optimized forwarding potential
@@ -360,7 +499,8 @@ 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,
+					struct batadv_orig_node **orig)
 {
 	struct ethhdr *ethhdr = eth_hdr(skb);
 
@@ -373,10 +513,12 @@ 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, orig);
+#if IS_ENABLED(CONFIG_IPV6)
 	case ETH_P_IPV6:
 		return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb,
-							 is_unsnoopable);
+							 is_unsnoopable, orig);
+#endif
 	default:
 		return -EINVAL;
 	}
@@ -544,12 +686,16 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 	bool is_unsnoopable = false;
 	struct ethhdr *ethhdr;
 
-	ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable);
+	ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable,
+					   orig);
 	if (ret == -ENOMEM)
 		return BATADV_FORW_NONE;
 	else if (ret < 0)
 		return BATADV_FORW_ALL;
 
+	if (*orig)
+		return BATADV_FORW_SINGLE;
+
 	ethhdr = eth_hdr(skb);
 
 	tt_count = batadv_tt_global_hash_count(bat_priv, ethhdr->h_dest,
@@ -581,6 +727,105 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 }
 
 /**
+ * batadv_mcast_snoop_query_ipv4 - snoop for the selected MLD querier
+ * @skb: the unencapsulated ethernet frame coming from the mesh
+ * @orig_node: the originator this frame came from
+ *
+ * Checks whether the given frame is a general IGMP query from the selected
+ * querier and if so memorizes the originator this frame came from.
+ */
+static void batadv_mcast_snoop_query_ipv4(struct sk_buff *skb,
+					  struct batadv_orig_node *orig_node)
+{
+	struct batadv_mcast_querier_state *querier;
+
+	if (ip_mc_check_igmp(skb, NULL) < 0)
+		return;
+
+	/* we are only interested in general queries (group == 0.0.0.0) */
+	if (igmp_hdr(skb)->type != IGMP_HOST_MEMBERSHIP_QUERY ||
+	    igmp_hdr(skb)->group)
+		return;
+
+	/* RFC4541, section 2.1.1.1.b) says: ignore queries from 0.0.0.0 */
+	if (!ip_hdr(skb)->saddr)
+		return;
+
+	querier = &orig_node->bat_priv->mcast.querier_ipv4;
+
+	spin_lock_bh(&querier->orig_lock);
+	rcu_assign_pointer(querier->orig, orig_node);
+	spin_unlock_bh(&querier->orig_lock);
+
+	batadv_dbg(BATADV_DBG_MCAST, orig_node->bat_priv,
+		   "Snooped IGMP Query from originator %pM\n", orig_node->orig);
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+/**
+ * batadv_mcast_snoop_query_ipv6 - snoop for the selected MLD querier
+ * @skb: the unencapsulated ethernet frame coming from the mesh
+ * @orig_node: the originator this frame came from
+ *
+ * Checks whether the given frame is a general MLD query from the selected
+ * querier and if so memorizes the originator this frame came from.
+ */
+static void batadv_mcast_snoop_query_ipv6(struct sk_buff *skb,
+					  struct batadv_orig_node *orig_node)
+{
+	struct mld_msg *mld;
+	struct batadv_mcast_querier_state *querier;
+
+	if (ipv6_mc_check_mld(skb, NULL) < 0)
+		return;
+
+	mld = (struct mld_msg *)icmp6_hdr(skb);
+
+	/* we are only interested in general queries (mca == ::) */
+	if (mld->mld_type != ICMPV6_MGM_QUERY ||
+	    !ipv6_addr_any(&mld->mld_mca))
+		return;
+
+	querier = &orig_node->bat_priv->mcast.querier_ipv6;
+
+	spin_lock_bh(&querier->orig_lock);
+	rcu_assign_pointer(querier->orig, orig_node);
+	spin_unlock_bh(&querier->orig_lock);
+
+	batadv_dbg(BATADV_DBG_MCAST, orig_node->bat_priv,
+		   "Snooped MLD Query from originator %pM\n", orig_node->orig);
+}
+#endif
+
+/**
+ * batadv_mcast_snoop_query - snoop the selected IGMP/MLD querier
+ * @skb: the unencapsulated ethernet frame coming from the mesh
+ * @orig_node: the originator this frame came from
+ *
+ * Checks whether the given frame is a general IGMP or MLD query
+ * from the selected querier and if so memorizes the originator
+ * this frame came from.
+ *
+ * This call might reallocate skb data.
+ */
+void batadv_mcast_snoop_query(struct sk_buff *skb,
+			      struct batadv_orig_node *orig_node)
+{
+	struct ethhdr *ethhdr = eth_hdr(skb);
+
+	switch (ntohs(ethhdr->h_proto)) {
+	case ETH_P_IP:
+		batadv_mcast_snoop_query_ipv4(skb, orig_node);
+		break;
+#if IS_ENABLED(CONFIG_IPV6)
+	case ETH_P_IPV6:
+		batadv_mcast_snoop_query_ipv6(skb, orig_node);
+		break;
+#endif
+	}
+}
+
+/**
  * batadv_mcast_want_unsnoop_update - update unsnoop 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
diff --git a/net/batman-adv/multicast.h b/net/batman-adv/multicast.h
index beb6e56..fb61db9 100644
--- a/net/batman-adv/multicast.h
+++ b/net/batman-adv/multicast.h
@@ -46,6 +46,9 @@ enum batadv_forw_mode
 batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 		       struct batadv_orig_node **mcast_single_orig);
 
+void batadv_mcast_snoop_query(struct sk_buff *skb,
+			      struct batadv_orig_node *orig_node);
+
 void batadv_mcast_init(struct batadv_priv *bat_priv);
 
 void batadv_mcast_free(struct batadv_priv *bat_priv);
@@ -65,6 +68,11 @@ batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
 	return BATADV_FORW_ALL;
 }
 
+static inline void batadv_mcast_snoop_query(struct sk_buff *skb,
+					    struct batadv_orig_node *orig_node)
+{
+}
+
 static inline int batadv_mcast_init(struct batadv_priv *bat_priv)
 {
 	return 0;
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index c002961..0a8c2ae 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -206,6 +206,8 @@ static int batadv_interface_tx(struct sk_buff *skb,
 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 		goto dropped;
 
+	skb_set_network_header(skb, ETH_HLEN);
+
 	soft_iface->trans_start = jiffies;
 	vid = batadv_get_vid(skb, 0);
 	ethhdr = eth_hdr(skb);
@@ -396,6 +398,7 @@ void batadv_interface_rx(struct net_device *soft_iface,
 
 	skb_pull_rcsum(skb, hdr_size);
 	skb_reset_mac_header(skb);
+	skb_set_network_header(skb, ETH_HLEN);
 
 	/* clean the netfilter state now that the batman-adv header has been
 	 * removed
@@ -458,6 +461,9 @@ void batadv_interface_rx(struct net_device *soft_iface,
 			skb->mark &= ~bat_priv->isolation_mark_mask;
 			skb->mark |= bat_priv->isolation_mark;
 		}
+
+		if (orig_node)
+			batadv_mcast_snoop_query(skb, orig_node);
 	} else if (batadv_is_ap_isolated(bat_priv, ethhdr->h_source,
 					 ethhdr->h_dest, vid)) {
 		goto dropped;
@@ -768,6 +774,11 @@ static int batadv_softif_init_late(struct net_device *dev)
 	atomic_set(&bat_priv->distributed_arp_table, 1);
 #endif
 #ifdef CONFIG_BATMAN_ADV_MCAST
+	rcu_assign_pointer(bat_priv->mcast.querier_ipv4.orig, NULL);
+	spin_lock_init(&bat_priv->mcast.querier_ipv4.orig_lock);
+	rcu_assign_pointer(bat_priv->mcast.querier_ipv6.orig, NULL);
+	spin_lock_init(&bat_priv->mcast.querier_ipv6.orig_lock);
+
 	bat_priv->mcast.flags = BATADV_NO_FLAGS;
 	atomic_set(&bat_priv->multicast_mode, 1);
 	atomic_set(&bat_priv->mcast.num_disabled, 0);
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 67d6348..3a5365f 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -640,12 +640,24 @@ struct batadv_priv_dat {
 
 #ifdef CONFIG_BATMAN_ADV_MCAST
 /**
+ * struct batadv_mcast_querier_state - IGMP/MLD querier state when bridged
+ * @orig: node on which the selected querier resides
+ * @orig_lock: protects updates of the selected querier in 'orig'
+ */
+struct batadv_mcast_querier_state {
+	struct batadv_orig_node __rcu *orig; /* rcu protected pointer */
+	spinlock_t orig_lock; /* protects updates of orig */
+};
+
+/**
  * struct batadv_priv_mcast - per mesh interface mcast data
  * @mla_list: list of multicast addresses we are currently announcing via TT
  * @want_all_unsnoopables_list: a list of orig_nodes wanting all unsnoopable
  *  multicast traffic
  * @want_all_ipv4_list: a list of orig_nodes wanting all IPv4 multicast traffic
  * @want_all_ipv6_list: a list of orig_nodes wanting all IPv6 multicast traffic
+ * @querier_ipv4: the current state of an IGMP querier in the mesh
+ * @querier_ipv6: the current state of an MLD querier in the mesh
  * @flags: the flags we have last sent in our mcast tvlv
  * @enabled: whether the multicast tvlv is currently enabled
  * @num_disabled: number of nodes that have no mcast tvlv
@@ -660,6 +672,8 @@ struct batadv_priv_mcast {
 	struct hlist_head want_all_unsnoopables_list;
 	struct hlist_head want_all_ipv4_list;
 	struct hlist_head want_all_ipv6_list;
+	struct batadv_mcast_querier_state querier_ipv4;
+	struct batadv_mcast_querier_state querier_ipv6;
 	uint8_t flags;
 	bool enabled;
 	atomic_t num_disabled;
-- 
1.7.10.4

[B.A.T.M.A.N.] [PATCHv6 2/3] batman-adv: Increase BATADV_TVLV_MCAST version number to 2

[Linus Lüssing]

The multicast optimizations bridge integration will require the just
implemented IGMP/MLD report handling later. Therefore bumping the
version number.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 net/batman-adv/multicast.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 72d561c..87a5942 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -225,7 +225,7 @@ static bool batadv_mcast_mla_tvlv_update(struct batadv_priv *bat_priv)
 	if (batadv_mcast_has_bridge(bat_priv)) {
 		if (bat_priv->mcast.enabled) {
 			batadv_tvlv_container_unregister(bat_priv,
-							 BATADV_TVLV_MCAST, 1);
+							 BATADV_TVLV_MCAST, 2);
 			bat_priv->mcast.enabled = false;
 		}
 
@@ -234,7 +234,7 @@ static bool batadv_mcast_mla_tvlv_update(struct batadv_priv *bat_priv)
 
 	if (!bat_priv->mcast.enabled ||
 	    mcast_data.flags != bat_priv->mcast.flags) {
-		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_MCAST, 1,
+		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_MCAST, 2,
 					       &mcast_data, sizeof(mcast_data));
 		bat_priv->mcast.flags = mcast_data.flags;
 		bat_priv->mcast.enabled = true;
@@ -984,7 +984,7 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
 void batadv_mcast_init(struct batadv_priv *bat_priv)
 {
 	batadv_tvlv_handler_register(bat_priv, batadv_mcast_tvlv_ogm_handler_v1,
-				     NULL, BATADV_TVLV_MCAST, 1,
+				     NULL, BATADV_TVLV_MCAST, 2,
 				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
 }
 
@@ -994,8 +994,8 @@ void batadv_mcast_init(struct batadv_priv *bat_priv)
  */
 void batadv_mcast_free(struct batadv_priv *bat_priv)
 {
-	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_MCAST, 1);
-	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_MCAST, 1);
+	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_MCAST, 2);
+	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_MCAST, 2);
 
 	batadv_mcast_mla_tt_retract(bat_priv, NULL);
 }
-- 
1.7.10.4

[B.A.T.M.A.N.] [PATCHv6 3/3] compat: Compat code for IGMP/MLD report unicast forwarding

[Linus Lüssing]

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
---
 Makefile                              |    4 +
 compat-include/linux/igmp.h           |   13 ++
 compat-include/linux/skbuff.h         |   14 ++
 compat-include/net/addrconf.h         |   13 ++
 compat-include/net/ip6_checksum.h     |   18 +++
 compat-include/net/ipv6.h             |   17 +++
 compat-include/net/mld.h              |   52 +++++++
 compat-sources/Makefile               |    3 +
 compat-sources/net/core/skbuff.c      |  179 ++++++++++++++++++++++++
 compat-sources/net/ipv4/igmp.c        |  241 +++++++++++++++++++++++++++++++++
 compat-sources/net/ipv6/mcast_snoop.c |  216 +++++++++++++++++++++++++++++
 11 files changed, 770 insertions(+)
 create mode 100644 compat-include/linux/igmp.h
 create mode 100644 compat-include/net/addrconf.h
 create mode 100644 compat-include/net/ip6_checksum.h
 create mode 100644 compat-include/net/ipv6.h
 create mode 100644 compat-include/net/mld.h
 create mode 100644 compat-sources/Makefile
 create mode 100644 compat-sources/net/core/skbuff.c
 create mode 100644 compat-sources/net/ipv4/igmp.c
 create mode 100644 compat-sources/net/ipv6/mcast_snoop.c

diff --git a/Makefile b/Makefile
index ee3be1d..69056d7 100644
--- a/Makefile
+++ b/Makefile
@@ -50,6 +50,10 @@ ifneq ($(REVISION),)
 NOSTDINC_FLAGS += -DBATADV_SOURCE_VERSION=\"$(REVISION)\"
 endif
 
+include $(PWD)/compat-sources/Makefile
+
+export batman-adv-y
+
 BUILD_FLAGS := \
 	M=$(PWD)/net/batman-adv \
 	CONFIG_BATMAN_ADV=m \
diff --git a/compat-include/linux/igmp.h b/compat-include/linux/igmp.h
new file mode 100644
index 0000000..f61ab79
--- /dev/null
+++ b/compat-include/linux/igmp.h
@@ -0,0 +1,13 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_LINUX_IGMP_H_
+#define _NET_BATMAN_ADV_COMPAT_LINUX_IGMP_H_
+
+#include <linux/version.h>
+#include_next <linux/igmp.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed);
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_LINUX_IGMP_H_ */
diff --git a/compat-include/linux/skbuff.h b/compat-include/linux/skbuff.h
index d363cc0..1d4f569 100644
--- a/compat-include/linux/skbuff.h
+++ b/compat-include/linux/skbuff.h
@@ -89,6 +89,20 @@ static inline void skb_reset_mac_len(struct sk_buff *skb)
 
 #define pskb_copy_for_clone pskb_copy
 
+__sum16 skb_checksum_simple_validate(struct sk_buff *skb);
+
+__sum16
+skb_checksum_validate(struct sk_buff *skb, int proto,
+		      __wsum (*compute_pseudo)(struct sk_buff *skb, int proto));
+
 #endif /* < KERNEL_VERSION(3, 16, 0) */
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
+				     unsigned int transport_len,
+				     __sum16(*skb_chkf)(struct sk_buff *skb));
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
+
 #endif	/* _NET_BATMAN_ADV_COMPAT_LINUX_SKBUFF_H_ */
diff --git a/compat-include/net/addrconf.h b/compat-include/net/addrconf.h
new file mode 100644
index 0000000..69c45d0
--- /dev/null
+++ b/compat-include/net/addrconf.h
@@ -0,0 +1,13 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_ADDRCONF_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_ADDRCONF_H_
+
+#include <linux/version.h>
+#include_next <net/addrconf.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed);
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_NET_ADDRCONF_H_ */
diff --git a/compat-include/net/ip6_checksum.h b/compat-include/net/ip6_checksum.h
new file mode 100644
index 0000000..fda0c07
--- /dev/null
+++ b/compat-include/net/ip6_checksum.h
@@ -0,0 +1,18 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_IP6_CHECKSUM_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_IP6_CHECKSUM_H_
+
+#include <linux/version.h>
+#include_next <net/ip6_checksum.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 0)
+
+static inline __wsum ip6_compute_pseudo(struct sk_buff *skb, int proto)
+{
+	return ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
+					    &ipv6_hdr(skb)->daddr,
+					    skb->len, proto, 0));
+}
+
+#endif /* < KERNEL_VERSION(3, 16, 0) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_NET_IP6_CHECKSUM_H_ */
diff --git a/compat-include/net/ipv6.h b/compat-include/net/ipv6.h
new file mode 100644
index 0000000..1e190d8
--- /dev/null
+++ b/compat-include/net/ipv6.h
@@ -0,0 +1,17 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_IPV6_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_IPV6_H_
+
+#include <linux/version.h>
+#include_next <net/ipv6.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 3, 0)
+
+#define ipv6_skip_exthdr(skb, start, nexthdrp, frag_offp) \
+	({ \
+		(void)frag_offp; \
+		ipv6_skip_exthdr(skb, start, nexthdrp); \
+	})
+
+#endif /* < KERNEL_VERSION(3, 3, 0) */
+
+#endif /* _NET_BATMAN_ADV_COMPAT_NET_IPV6_H_ */
diff --git a/compat-include/net/mld.h b/compat-include/net/mld.h
new file mode 100644
index 0000000..e041eb6
--- /dev/null
+++ b/compat-include/net/mld.h
@@ -0,0 +1,52 @@
+#ifndef _NET_BATMAN_ADV_COMPAT_NET_MLD_H_
+#define _NET_BATMAN_ADV_COMPAT_NET_MLD_H_
+
+#include <linux/version.h>
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 35)
+#include_next <net/mld.h>
+#endif /* >= KERNEL_VERSION(2, 6, 35) */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 35)
+struct mld_msg {
+	struct icmp6hdr		mld_hdr;
+	struct in6_addr		mld_mca;
+};
+
+#define mld_type		mld_hdr.icmp6_type
+
+struct mld2_grec {
+	__u8		grec_type;
+	__u8		grec_auxwords;
+	__be16		grec_nsrcs;
+	struct in6_addr	grec_mca;
+	struct in6_addr	grec_src[0];
+};
+
+struct mld2_report {
+	struct icmp6hdr		mld2r_hdr;
+	struct mld2_grec	mld2r_grec[0];
+};
+
+struct mld2_query {
+	struct icmp6hdr		mld2q_hdr;
+	struct in6_addr		mld2q_mca;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+	__u8			mld2q_qrv:3,
+				mld2q_suppress:1,
+				mld2q_resv2:4;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+	__u8			mld2q_resv2:4,
+				mld2q_suppress:1,
+				mld2q_qrv:3;
+#else
+#error "Please fix <asm/byteorder.h>"
+#endif
+	__u8			mld2q_qqic;
+	__be16			mld2q_nsrcs;
+	struct in6_addr		mld2q_srcs[0];
+};
+
+#endif /* < KERNEL_VERSION(2, 6, 35) */
+
+#endif	/* _NET_BATMAN_ADV_COMPAT_NET_MLD_H_ */
diff --git a/compat-sources/Makefile b/compat-sources/Makefile
new file mode 100644
index 0000000..c364ded
--- /dev/null
+++ b/compat-sources/Makefile
@@ -0,0 +1,3 @@
+batman-adv-y += ../../compat-sources/net/core/skbuff.o
+batman-adv-y += ../../compat-sources/net/ipv4/igmp.o
+batman-adv-y += ../../compat-sources/net/ipv6/mcast_snoop.o
diff --git a/compat-sources/net/core/skbuff.c b/compat-sources/net/core/skbuff.c
new file mode 100644
index 0000000..7ad23fe
--- /dev/null
+++ b/compat-sources/net/core/skbuff.c
@@ -0,0 +1,179 @@
+/*
+ *	Routines having to do with the 'struct sk_buff' memory handlers.
+ *
+ *	Authors:	Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *			Florian La Roche <rzsfl@rz.uni-sb.de>
+ *
+ *	Fixes:
+ *		Alan Cox	:	Fixed the worst of the load
+ *					balancer bugs.
+ *		Dave Platt	:	Interrupt stacking fix.
+ *	Richard Kooijman	:	Timestamp fixes.
+ *		Alan Cox	:	Changed buffer format.
+ *		Alan Cox	:	destructor hook for AF_UNIX etc.
+ *		Linus Torvalds	:	Better skb_clone.
+ *		Alan Cox	:	Added skb_copy.
+ *		Alan Cox	:	Added all the changed routines Linus
+ *					only put in the headers
+ *		Ray VanTassle	:	Fixed --skb->lock in free
+ *		Alan Cox	:	skb_copy copy arp field
+ *		Andi Kleen	:	slabified it.
+ *		Robert Olsson	:	Removed skb_head_pool
+ *
+ *	NOTE:
+ *		The __skb_ routines should be called with interrupts
+ *	disabled, or you better be *real* sure that the operation is atomic
+ *	with respect to whatever list is being frobbed (e.g. via lock_sock()
+ *	or via disabling bottom half handlers, etc).
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/ipv6.h>
+#include <linux/skbuff.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 16, 0)
+
+/* Compare with:
+ * "bridge: multicast: call skb_checksum_{simple_, }validate"
+ */
+__sum16 skb_checksum_simple_validate(struct sk_buff *skb)
+{
+	switch (skb->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (!csum_fold(skb->csum))
+			break;
+		/* fall through */
+	case CHECKSUM_NONE:
+		skb->csum = 0;
+		if (skb_checksum_complete(skb))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* Watch out: Not as generic as upstream
+ * - redefines this method to only fit with ICMPV6
+ *
+ * Compare with:
+ * "bridge: multicast: call skb_checksum_{simple_, }validate"
+ */
+__sum16
+skb_checksum_validate(struct sk_buff *skb, int proto,
+		      __wsum (*compute_pseudo)(struct sk_buff *skb, int proto))
+{
+	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+
+	switch (skb->ip_summed) {
+	case CHECKSUM_COMPLETE:
+		if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, skb->len,
+				     IPPROTO_ICMPV6, skb->csum))
+			break;
+		/*FALLTHROUGH*/
+	case CHECKSUM_NONE:
+		skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
+							 &ip6h->daddr,
+							 skb->len,
+							 IPPROTO_ICMPV6, 0));
+		if (__skb_checksum_complete(skb))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+#endif /* < KERNEL_VERSION(3, 16, 0) */
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+/**
+ * skb_checksum_maybe_trim - maybe trims the given skb
+ * @skb: the skb to check
+ * @transport_len: the data length beyond the network header
+ *
+ * Checks whether the given skb has data beyond the given transport length.
+ * If so, returns a cloned skb trimmed to this transport length.
+ * Otherwise returns the provided skb. Returns NULL in error cases
+ * (e.g. transport_len exceeds skb length or out-of-memory).
+ *
+ * Caller needs to set the skb transport header and release the returned skb.
+ * Provided skb is consumed.
+ */
+static struct sk_buff *skb_checksum_maybe_trim(struct sk_buff *skb,
+					       unsigned int transport_len)
+{
+	struct sk_buff *skb_chk;
+	unsigned int len = skb_transport_offset(skb) + transport_len;
+	int ret;
+
+	if (skb->len < len) {
+		kfree_skb(skb);
+		return NULL;
+	} else if (skb->len == len) {
+		return skb;
+	}
+
+	skb_chk = skb_clone(skb, GFP_ATOMIC);
+	kfree_skb(skb);
+
+	if (!skb_chk)
+		return NULL;
+
+	ret = pskb_trim_rcsum(skb_chk, len);
+	if (ret) {
+		kfree_skb(skb_chk);
+		return NULL;
+	}
+
+	return skb_chk;
+}
+
+/**
+ * skb_checksum_trimmed - validate checksum of an skb
+ * @skb: the skb to check
+ * @transport_len: the data length beyond the network header
+ * @skb_chkf: checksum function to use
+ *
+ * Applies the given checksum function skb_chkf to the provided skb.
+ * Returns a checked and maybe trimmed skb. Returns NULL on error.
+ *
+ * If the skb has data beyond the given transport length, then a
+ * trimmed & cloned skb is checked and returned.
+ *
+ * Caller needs to set the skb transport header and release the returned skb.
+ * Provided skb is consumed.
+ */
+struct sk_buff *skb_checksum_trimmed(struct sk_buff *skb,
+				     unsigned int transport_len,
+				     __sum16(*skb_chkf)(struct sk_buff *skb))
+{
+	struct sk_buff *skb_chk;
+	unsigned int offset = skb_transport_offset(skb);
+	__sum16 ret;
+
+	skb_chk = skb_checksum_maybe_trim(skb, transport_len);
+	if (!skb_chk)
+		return NULL;
+
+	if (!pskb_may_pull(skb_chk, offset)) {
+		kfree_skb(skb_chk);
+		return NULL;
+	}
+
+	__skb_pull(skb_chk, offset);
+	ret = skb_chkf(skb_chk);
+	__skb_push(skb_chk, offset);
+
+	if (ret) {
+		kfree_skb(skb_chk);
+		return NULL;
+	}
+
+	return skb_chk;
+}
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
diff --git a/compat-sources/net/ipv4/igmp.c b/compat-sources/net/ipv4/igmp.c
new file mode 100644
index 0000000..457a05e
--- /dev/null
+++ b/compat-sources/net/ipv4/igmp.c
@@ -0,0 +1,241 @@
+/*
+ *	Linux NET3:	Internet Group Management Protocol  [IGMP]
+ *
+ *	This code implements the IGMP protocol as defined in RFC1112. There has
+ *	been a further revision of this protocol since which is now supported.
+ *
+ *	If you have trouble with this module be careful what gcc you have used,
+ *	the older version didn't come out right using gcc 2.5.8, the newer one
+ *	seems to fall out with gcc 2.6.2.
+ *
+ *	Authors:
+ *		Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *
+ *	Fixes:
+ *
+ *		Alan Cox	:	Added lots of __inline__ to optimise
+ *					the memory usage of all the tiny little
+ *					functions.
+ *		Alan Cox	:	Dumped the header building experiment.
+ *		Alan Cox	:	Minor tweaks ready for multicast routing
+ *					and extended IGMP protocol.
+ *		Alan Cox	:	Removed a load of inline directives. Gcc 2.5.8
+ *					writes utterly bogus code otherwise (sigh)
+ *					fixed IGMP loopback to behave in the manner
+ *					desired by mrouted, fixed the fact it has been
+ *					broken since 1.3.6 and cleaned up a few minor
+ *					points.
+ *
+ *		Chih-Jen Chang	:	Tried to revise IGMP to Version 2
+ *		Tsu-Sheng Tsao		E-mail: chihjenc@scf.usc.edu and tsusheng@scf.usc.edu
+ *					The enhancements are mainly based on Steve Deering's
+ * 					ipmulti-3.5 source code.
+ *		Chih-Jen Chang	:	Added the igmp_get_mrouter_info and
+ *		Tsu-Sheng Tsao		igmp_set_mrouter_info to keep track of
+ *					the mrouted version on that device.
+ *		Chih-Jen Chang	:	Added the max_resp_time parameter to
+ *		Tsu-Sheng Tsao		igmp_heard_query(). Using this parameter
+ *					to identify the multicast router version
+ *					and do what the IGMP version 2 specified.
+ *		Chih-Jen Chang	:	Added a timer to revert to IGMP V2 router
+ *		Tsu-Sheng Tsao		if the specified time expired.
+ *		Alan Cox	:	Stop IGMP from 0.0.0.0 being accepted.
+ *		Alan Cox	:	Use GFP_ATOMIC in the right places.
+ *		Christian Daudt :	igmp timer wasn't set for local group
+ *					memberships but was being deleted,
+ *					which caused a "del_timer() called
+ *					from %p with timer not initialized\n"
+ *					message (960131).
+ *		Christian Daudt :	removed del_timer from
+ *					igmp_timer_expire function (960205).
+ *             Christian Daudt :       igmp_heard_report now only calls
+ *                                     igmp_timer_expire if tm->running is
+ *                                     true (960216).
+ *		Malcolm Beattie :	ttl comparison wrong in igmp_rcv made
+ *					igmp_heard_query never trigger. Expiry
+ *					miscalculation fixed in igmp_heard_query
+ *					and random() made to return unsigned to
+ *					prevent negative expiry times.
+ *		Alexey Kuznetsov:	Wrong group leaving behaviour, backport
+ *					fix from pending 2.1.x patches.
+ *		Alan Cox:		Forget to enable FDDI support earlier.
+ *		Alexey Kuznetsov:	Fixed leaving groups on device down.
+ *		Alexey Kuznetsov:	Accordance to igmp-v2-06 draft.
+ *		David L Stevens:	IGMPv3 support, with help from
+ *					Vinay Kulkarni
+ */
+
+#include <linux/igmp.h>
+#include <linux/ip.h>
+#include <linux/skbuff.h>
+#include <net/ip.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+static int ip_mc_check_iphdr(struct sk_buff *skb)
+{
+	const struct iphdr *iph;
+	unsigned int len;
+	unsigned int offset = skb_network_offset(skb) + sizeof(*iph);
+
+	if (!pskb_may_pull(skb, offset))
+		return -EINVAL;
+
+	iph = ip_hdr(skb);
+
+	if (iph->version != 4 || ip_hdrlen(skb) < sizeof(*iph))
+		return -EINVAL;
+
+	offset += ip_hdrlen(skb) - sizeof(*iph);
+
+	if (!pskb_may_pull(skb, offset))
+		return -EINVAL;
+
+	iph = ip_hdr(skb);
+
+	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
+		return -EINVAL;
+
+	len = skb_network_offset(skb) + ntohs(iph->tot_len);
+	if (skb->len < len || len < offset)
+		return -EINVAL;
+
+	skb_set_transport_header(skb, offset);
+
+	return 0;
+}
+
+static int ip_mc_check_igmp_reportv3(struct sk_buff *skb)
+{
+	unsigned int len = skb_transport_offset(skb);
+
+	len += sizeof(struct igmpv3_report);
+
+	return pskb_may_pull(skb, len) ? 0 : -EINVAL;
+}
+
+static int ip_mc_check_igmp_query(struct sk_buff *skb)
+{
+	unsigned int len = skb_transport_offset(skb);
+
+	len += sizeof(struct igmphdr);
+	if (skb->len < len)
+		return -EINVAL;
+
+	/* IGMPv{1,2}? */
+	if (skb->len != len) {
+		/* or IGMPv3? */
+		len += sizeof(struct igmpv3_query) - sizeof(struct igmphdr);
+		if (skb->len < len || !pskb_may_pull(skb, len))
+			return -EINVAL;
+	}
+
+	/* RFC2236+RFC3376 (IGMPv2+IGMPv3) require the multicast link layer
+	 * all-systems destination addresses (224.0.0.1) for general queries
+	 */
+	if (!igmp_hdr(skb)->group &&
+	    ip_hdr(skb)->daddr != htonl(INADDR_ALLHOSTS_GROUP))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ip_mc_check_igmp_msg(struct sk_buff *skb)
+{
+	switch (igmp_hdr(skb)->type) {
+	case IGMP_HOST_LEAVE_MESSAGE:
+	case IGMP_HOST_MEMBERSHIP_REPORT:
+	case IGMPV2_HOST_MEMBERSHIP_REPORT:
+		/* fall through */
+		return 0;
+	case IGMPV3_HOST_MEMBERSHIP_REPORT:
+		return ip_mc_check_igmp_reportv3(skb);
+	case IGMP_HOST_MEMBERSHIP_QUERY:
+		return ip_mc_check_igmp_query(skb);
+	default:
+		return -ENOMSG;
+	}
+}
+
+static inline __sum16 ip_mc_validate_checksum(struct sk_buff *skb)
+{
+	return skb_checksum_simple_validate(skb);
+}
+
+static int __ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+
+{
+	struct sk_buff *skb_chk;
+	unsigned int transport_len;
+	unsigned int len = skb_transport_offset(skb) + sizeof(struct igmphdr);
+	int ret;
+
+	transport_len = ntohs(ip_hdr(skb)->tot_len) - ip_hdrlen(skb);
+
+	skb_get(skb);
+	skb_chk = skb_checksum_trimmed(skb, transport_len,
+				       ip_mc_validate_checksum);
+	if (!skb_chk)
+		return -EINVAL;
+
+	if (!pskb_may_pull(skb_chk, len)) {
+		kfree_skb(skb_chk);
+		return -EINVAL;
+	}
+
+	ret = ip_mc_check_igmp_msg(skb_chk);
+	if (ret) {
+		kfree_skb(skb_chk);
+		return ret;
+	}
+
+	if (skb_trimmed)
+		*skb_trimmed = skb_chk;
+	else
+		kfree_skb(skb_chk);
+
+	return 0;
+}
+
+/**
+ * ip_mc_check_igmp - checks whether this is a sane IGMP packet
+ * @skb: the skb to validate
+ * @skb_trimmed: to store an skb pointer trimmed to IPv4 packet tail (optional)
+ *
+ * Checks whether an IPv4 packet is a valid IGMP packet. If so sets
+ * skb network and transport headers accordingly and returns zero.
+ *
+ * -EINVAL: A broken packet was detected, i.e. it violates some internet
+ *  standard
+ * -ENOMSG: IP header validation succeeded but it is not an IGMP packet.
+ * -ENOMEM: A memory allocation failure happened.
+ *
+ * Optionally, an skb pointer might be provided via skb_trimmed (or set it
+ * to NULL): After parsing an IGMP packet successfully it will point to
+ * an skb which has its tail aligned to the IP packet end. This might
+ * either be the originally provided skb or a trimmed, cloned version if
+ * the skb frame had data beyond the IP packet. A cloned skb allows us
+ * to leave the original skb and its full frame unchanged (which might be
+ * desirable for layer 2 frame jugglers).
+ *
+ * The caller needs to release a reference count from any returned skb_trimmed.
+ */
+int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+{
+	int ret = ip_mc_check_iphdr(skb);
+
+	if (ret < 0)
+		return ret;
+
+	if (ip_hdr(skb)->protocol != IPPROTO_IGMP)
+		return -ENOMSG;
+
+	return __ip_mc_check_igmp(skb, skb_trimmed);
+}
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
diff --git a/compat-sources/net/ipv6/mcast_snoop.c b/compat-sources/net/ipv6/mcast_snoop.c
new file mode 100644
index 0000000..3f46ed3
--- /dev/null
+++ b/compat-sources/net/ipv6/mcast_snoop.c
@@ -0,0 +1,216 @@
+/* Copyright (C) 2010: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
+ * Copyright (C) 2015: Linus Lüssing <linus.luessing@c0d3.blue>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Based on the MLD support added to br_multicast.c by YOSHIFUJI Hideaki.
+ */
+
+#include <linux/skbuff.h>
+#include <net/ipv6.h>
+#include <net/mld.h>
+#include <net/addrconf.h>
+#include <net/ip6_checksum.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 2, 0)
+
+static int ipv6_mc_check_ip6hdr(struct sk_buff *skb)
+{
+	const struct ipv6hdr *ip6h;
+	unsigned int len;
+	unsigned int offset = skb_network_offset(skb) + sizeof(*ip6h);
+
+	if (!pskb_may_pull(skb, offset))
+		return -EINVAL;
+
+	ip6h = ipv6_hdr(skb);
+
+	if (ip6h->version != 6)
+		return -EINVAL;
+
+	len = offset + ntohs(ip6h->payload_len);
+	if (skb->len < len || len <= offset)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ipv6_mc_check_exthdrs(struct sk_buff *skb)
+{
+	const struct ipv6hdr *ip6h;
+	int offset;
+	u8 nexthdr;
+	__be16 frag_off;
+
+	ip6h = ipv6_hdr(skb);
+
+	if (ip6h->nexthdr != IPPROTO_HOPOPTS)
+		return -ENOMSG;
+
+	nexthdr = ip6h->nexthdr;
+	offset = skb_network_offset(skb) + sizeof(*ip6h);
+	offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
+
+	if (offset < 0)
+		return -EINVAL;
+
+	if (nexthdr != IPPROTO_ICMPV6)
+		return -ENOMSG;
+
+	skb_set_transport_header(skb, offset);
+
+	return 0;
+}
+
+static int ipv6_mc_check_mld_reportv2(struct sk_buff *skb)
+{
+	unsigned int len = skb_transport_offset(skb);
+
+	len += sizeof(struct mld2_report);
+
+	return pskb_may_pull(skb, len) ? 0 : -EINVAL;
+}
+
+static int ipv6_mc_check_mld_query(struct sk_buff *skb)
+{
+	struct mld_msg *mld;
+	unsigned int len = skb_transport_offset(skb);
+
+	/* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */
+	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL))
+		return -EINVAL;
+
+	len += sizeof(struct mld_msg);
+	if (skb->len < len)
+		return -EINVAL;
+
+	/* MLDv1? */
+	if (skb->len != len) {
+		/* or MLDv2? */
+		len += sizeof(struct mld2_query) - sizeof(struct mld_msg);
+		if (skb->len < len || !pskb_may_pull(skb, len))
+			return -EINVAL;
+	}
+
+	mld = (struct mld_msg *)skb_transport_header(skb);
+
+	/* RFC2710+RFC3810 (MLDv1+MLDv2) require the multicast link layer
+	 * all-nodes destination address (ff02::1) for general queries
+	 */
+	if (ipv6_addr_any(&mld->mld_mca) &&
+	    !ipv6_addr_is_ll_all_nodes(&ipv6_hdr(skb)->daddr))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ipv6_mc_check_mld_msg(struct sk_buff *skb)
+{
+	struct mld_msg *mld = (struct mld_msg *)skb_transport_header(skb);
+
+	switch (mld->mld_type) {
+	case ICMPV6_MGM_REDUCTION:
+	case ICMPV6_MGM_REPORT:
+		/* fall through */
+		return 0;
+	case ICMPV6_MLD2_REPORT:
+		return ipv6_mc_check_mld_reportv2(skb);
+	case ICMPV6_MGM_QUERY:
+		return ipv6_mc_check_mld_query(skb);
+	default:
+		return -ENOMSG;
+	}
+}
+
+static inline __sum16 ipv6_mc_validate_checksum(struct sk_buff *skb)
+{
+	return skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo);
+}
+
+static int __ipv6_mc_check_mld(struct sk_buff *skb,
+			       struct sk_buff **skb_trimmed)
+
+{
+	struct sk_buff *skb_chk = NULL;
+	unsigned int transport_len;
+	unsigned int len = skb_transport_offset(skb) + sizeof(struct mld_msg);
+	int ret;
+
+	transport_len = ntohs(ipv6_hdr(skb)->payload_len);
+	transport_len -= skb_transport_offset(skb) - sizeof(struct ipv6hdr);
+
+	skb_get(skb);
+	skb_chk = skb_checksum_trimmed(skb, transport_len,
+				       ipv6_mc_validate_checksum);
+	if (!skb_chk)
+		return -EINVAL;
+
+	if (!pskb_may_pull(skb_chk, len)) {
+		kfree_skb(skb_chk);
+		return -EINVAL;
+	}
+
+	ret = ipv6_mc_check_mld_msg(skb_chk);
+	if (ret) {
+		kfree_skb(skb_chk);
+		return ret;
+	}
+
+	if (skb_trimmed)
+		*skb_trimmed = skb_chk;
+	else
+		kfree_skb(skb_chk);
+
+	return 0;
+}
+
+/**
+ * ipv6_mc_check_mld - checks whether this is a sane MLD packet
+ * @skb: the skb to validate
+ * @skb_trimmed: to store an skb pointer trimmed to IPv6 packet tail (optional)
+ *
+ * Checks whether an IPv6 packet is a valid MLD packet. If so sets
+ * skb network and transport headers accordingly and returns zero.
+ *
+ * -EINVAL: A broken packet was detected, i.e. it violates some internet
+ *  standard
+ * -ENOMSG: IP header validation succeeded but it is not an MLD packet.
+ * -ENOMEM: A memory allocation failure happened.
+ *
+ * Optionally, an skb pointer might be provided via skb_trimmed (or set it
+ * to NULL): After parsing an MLD packet successfully it will point to
+ * an skb which has its tail aligned to the IP packet end. This might
+ * either be the originally provided skb or a trimmed, cloned version if
+ * the skb frame had data beyond the IP packet. A cloned skb allows us
+ * to leave the original skb and its full frame unchanged (which might be
+ * desirable for layer 2 frame jugglers).
+ *
+ * The caller needs to release a reference count from any returned skb_trimmed.
+ */
+int ipv6_mc_check_mld(struct sk_buff *skb, struct sk_buff **skb_trimmed)
+{
+	int ret;
+
+	ret = ipv6_mc_check_ip6hdr(skb);
+	if (ret < 0)
+		return ret;
+
+	ret = ipv6_mc_check_exthdrs(skb);
+	if (ret < 0)
+		return ret;
+
+	return __ipv6_mc_check_mld(skb, skb_trimmed);
+}
+
+#endif /* < KERNEL_VERSION(4, 2, 0) */
-- 
1.7.10.4