[B.A.T.M.A.N.] [PATCHv9 5/5] batman-adv: Send multicast packets to nodes with a WANT_ALL flag

Linus Lüssing
2013-08-15T19:21:19Z

With this patch a node sends IPv4 multicast packets to nodes which
have a BATADV_MCAST_WANT_ALL_IPV4 flag set and IPv6 multicast packets
to nodes which have a BATADV_MCAST_WANT_ALL_IPV6 flag set, too.

Why is this needed? There are scenarios involving bridges where
multicast report snooping and multicast TT announcements are not
sufficient, which would lead to packet loss for some nodes otherwise:

MLDv1 and IGMPv1/IGMPv2 have a suppression mechanism
for multicast listener reports. When we have an MLDv1/IGMPv1/IGMPv2
querier behind a bridge then our snooping bridge is potentially not
going to see any reports even though listeners exist because according
to RFC4541 such reports are only forwarded to multicast routers:

-----------------------------------------------------------
---------------
{Querier}---|Snoop. Switch|----{Listener}
---------------
\ ^
-------
| br0 | < ???
-------
\
_-~---~_
_-~/ ~-_
~ batman-adv \-----{Sender}
\~_ cloud ~/
-~~__-__-~_/

I) MLDv1 Query: {Querier} -> flooded
II) MLDv1 Report: {Listener} -> {Querier}

-> br0 cannot detect the {Listener}
=> Packets from {Sender} need to be forwarded to all
detected listeners and MLDv1/IGMPv1/IGMPv2 queriers.

-----------------------------------------------------------

Note that we do not need to explicitly forward to MLDv2/IGMPv3 queriers,
because these protocols have no report suppression: A bridge has no
trouble detecting MLDv2/IGMPv3 listeners.

Even though we do not support bridges yet we need to provide the
according infrastructure already to not break compatibility later.

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
main.c | 7 ++
multicast.c | 194 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
multicast.h | 15 ++++-
packet.h | 4 ++
send.c | 23 +++++++
send.h | 3 +
soft-interface.c | 9 ++-
types.h | 16 +++++
8 files changed, 267 insertions(+), 4 deletions(-)

diff --git a/main.c b/main.c
index 69dbb75..7e122d0 100644
--- a/main.c
+++ b/main.c
@@ -112,6 +112,9 @@ int batadv_mesh_init(struct net_device *soft_iface)
spin_lock_init(&bat_priv->tt.last_changeset_lock);
spin_lock_init(&bat_priv->tt.commit_lock);
spin_lock_init(&bat_priv->gw.list_lock);
+#ifdef CONFIG_BATMAN_ADV_MCAST
+ spin_lock_init(&bat_priv->mcast.want_lists_lock);
+#endif
spin_lock_init(&bat_priv->tvlv.container_list_lock);
spin_lock_init(&bat_priv->tvlv.handler_list_lock);
spin_lock_init(&bat_priv->softif_vlan_list_lock);
@@ -119,6 +122,10 @@ int batadv_mesh_init(struct net_device *soft_iface)
INIT_HLIST_HEAD(&bat_priv->forw_bat_list);
INIT_HLIST_HEAD(&bat_priv->forw_bcast_list);
INIT_HLIST_HEAD(&bat_priv->gw.list);
+#ifdef CONFIG_BATMAN_ADV_MCAST
+ INIT_HLIST_HEAD(&bat_priv->mcast.want_all_ipv4_list);
+ INIT_HLIST_HEAD(&bat_priv->mcast.want_all_ipv6_list);
+#endif
INIT_LIST_HEAD(&bat_priv->tt.changes_list);
INIT_LIST_HEAD(&bat_priv->tt.req_list);
INIT_LIST_HEAD(&bat_priv->tt.roam_list);
diff --git a/multicast.c b/multicast.c
index ae7992a..892a3ce 100644
--- a/multicast.c
+++ b/multicast.c
@@ -376,14 +376,53 @@ static int batadv_mcast_forw_mode_check(struct sk_buff *skb,
}

/**
+ * batadv_mcast_want_all_count - number of nodes with unspecific mcast interest
+ * @bat_priv: the bat priv with all the soft interface information
+ * @ethhdr: ethernet header of a packet
+ * @want_all_list: pointer to a mcast want list in our bat_priv
+ *
+ * Return the number of nodes which want all IPv4 multicast traffic if
+ * the given ethhdr is from an IPv4 packet or the number of nodes which want
+ * all IPv6 traffic if it matches an IPv6 packet and set the want_list to the
+ * according one in our bat_priv. For other frame types leave the want_list
+ * untouched and return zero.
+ */
+static int batadv_mcast_want_all_count(struct batadv_priv *bat_priv,
+ struct ethhdr *ethhdr,
+ struct hlist_head **want_all_list)
+{
+ int ret;
+
+ switch (ntohs(ethhdr->h_proto)) {
+ case ETH_P_IP:
+ ret = atomic_read(&bat_priv->mcast.num_want_all_ipv4);
+ if (ret)
+ *want_all_list = &bat_priv->mcast.want_all_ipv4_list;
+ break;
+ case ETH_P_IPV6:
+ ret = atomic_read(&bat_priv->mcast.num_want_all_ipv6);
+ if (ret)
+ *want_all_list = &bat_priv->mcast.want_all_ipv6_list;
+ break;
+ default:
+ /* we shouldn't be here... */
+ ret = 0;
+ }
+
+ return ret;
+}
+
+/**
* batadv_mcast_forw_mode - check on how to forward a multicast packet
* @skb: The multicast packet to check
* @bat_priv: the bat priv with all the soft interface information
+ * @want_all_list: pointer to a mcast want list in our bat_priv
*
* Return the forwarding mode as enum batadv_forw_mode.
*/
enum batadv_forw_mode
-batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv)
+batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv,
+ struct hlist_head **want_all_list)
{
struct ethhdr *ethhdr = (struct ethhdr *)(skb->data);
int ret;
@@ -396,6 +435,7 @@ batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv)

ret = batadv_tt_global_hash_count(bat_priv, ethhdr->h_dest,
BATADV_NO_FLAGS);
+ ret += batadv_mcast_want_all_count(bat_priv, ethhdr, want_all_list);

switch (ret) {
case 0:
@@ -408,6 +448,72 @@ batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv)
}

/**
+ * batadv_mcast_want_all_ipv4_node_get - get an orig_node with want_all_ipv4
+ * @head: list of originators that want all IPv4 multicast traffic
+ *
+ * Return the first orig_node from the given want_all_ipv4 list. Increases
+ * the refcount of the returned orig_node.
+ */
+static struct batadv_orig_node *
+batadv_mcast_want_all_ipv4_node_get(struct hlist_head *head)
+{
+ struct batadv_orig_node *orig_node = NULL;
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(orig_node, head,
+ mcast_want_all_ipv4_node) {
+ if (atomic_inc_not_zero(&orig_node->refcount))
+ break;
+ }
+ rcu_read_unlock();
+
+ return orig_node;
+}
+
+/**
+ * batadv_mcast_want_all_ipv6_node_get - get an orig_node with want_all_ipv6
+ * @head: list of originators that want all IPv6 multicast traffic
+ *
+ * Return the first orig_node from the given want_all_ipv6 list. Increases
+ * the refcount of the returned orig_node.
+ */
+static struct batadv_orig_node *
+batadv_mcast_want_all_ipv6_node_get(struct hlist_head *head)
+{
+ struct batadv_orig_node *orig_node = NULL;
+
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(orig_node, head,
+ mcast_want_all_ipv6_node) {
+ if (atomic_inc_not_zero(&orig_node->refcount))
+ break;
+ }
+ rcu_read_unlock();
+
+ return orig_node;
+}
+
+/**
+ * batadv_mcast_want_all_node_get - get an orig_node with an mcast want list
+ * @want_all_list: list of originators that want all IPv4 or IPv6 mcast traffic
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Return the first orig_node from the given want_all list. Increases the
+ * refcount of the returned orig_node.
+ */
+struct batadv_orig_node *
+batadv_mcast_want_all_node_get(struct hlist_head *want_all_list,
+ struct batadv_priv *bat_priv)
+{
+ if (want_all_list == &bat_priv->mcast.want_all_ipv4_list)
+ return batadv_mcast_want_all_ipv4_node_get(want_all_list);
+ else if (want_all_list == &bat_priv->mcast.want_all_ipv6_list)
+ return batadv_mcast_want_all_ipv6_node_get(want_all_list);
+ else
+ return NULL;
+}
+
+/**
* batadv_mcast_counter_update - update the counter of a flag
* @flag: the flag we want to update counters for
* @flag_counter: the counter we might update
@@ -427,6 +533,58 @@ static void batadv_mcast_counter_update(uint8_t flag, atomic_t *flag_counter,
}

/**
+ * batadv_mcast_list_add - grab a lock and add a node to a head
+ * @node: the node to add
+ * @head: the head to add the node to
+ * @lock: the lock to grab while adding the node to the head
+ */
+static void batadv_mcast_list_add(struct hlist_node *node,
+ struct hlist_head *head,
+ spinlock_t *lock)
+{
+ spin_lock_bh(lock);
+ hlist_add_head_rcu(node, head);
+ spin_unlock_bh(lock);
+}
+
+/**
+ * batadv_mcast_list_del - grab a lock and delete a node from its list
+ * @node: the node to delete from its list
+ * @lock: the lock to grab while deleting the node from its list
+ */
+static void batadv_mcast_list_del(struct hlist_node *node, spinlock_t *lock)
+{
+ spin_lock_bh(lock);
+ hlist_del_rcu(node);
+ spin_unlock_bh(lock);
+}
+
+/**
+ * batadv_mcast_list_update - update the list of a flag
+ * @flag: the flag we want to update the list for
+ * @node: a list node of an originator
+ * @head: the list head the node might be added to
+ * @lock: the lock that synchronizes list modifications
+ * @new_flags: the new capability bitset of a node
+ * @old_flags: the current, to be updated bitset of a node
+ *
+ * Update the list of the given node/head with the help of the new flag
+ * information of an originator to contain the nodes which have the given
+ * flag set.
+ */
+static void batadv_mcast_list_update(uint8_t flag,
+ struct hlist_node *node,
+ struct hlist_head *head,
+ spinlock_t *lock,
+ uint8_t new_flags, int old_flags)
+{
+ if (new_flags & flag && !(old_flags & flag))
+ batadv_mcast_list_add(node, head, lock);
+ else if (!(new_flags & flag) && old_flags & flag)
+ batadv_mcast_list_del(node, lock);
+}
+
+/**
* batadv_mcast_tvlv_ogm_handler_v1 - process incoming multicast tvlv container
* @bat_priv: the bat priv with all the soft interface information
* @orig: the orig_node of the ogm
@@ -462,6 +620,23 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_UNSNOOPABLES,
&bat_priv->mcast.num_want_all_unsnoopables,
mcast_flags, orig->mcast_flags);
+ batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_IPV4,
+ &bat_priv->mcast.num_want_all_ipv4,
+ mcast_flags, orig->mcast_flags);
+ batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_IPV6,
+ &bat_priv->mcast.num_want_all_ipv6,
+ mcast_flags, orig->mcast_flags);
+
+ batadv_mcast_list_update(BATADV_MCAST_WANT_ALL_IPV4,
+ &orig->mcast_want_all_ipv4_node,
+ &bat_priv->mcast.want_all_ipv4_list,
+ &bat_priv->mcast.want_lists_lock,
+ mcast_flags, orig->mcast_flags);
+ batadv_mcast_list_update(BATADV_MCAST_WANT_ALL_IPV6,
+ &orig->mcast_want_all_ipv6_node,
+ &bat_priv->mcast.want_all_ipv6_list,
+ &bat_priv->mcast.want_lists_lock,
+ mcast_flags, orig->mcast_flags);

orig->mcast_flags = mcast_flags;
}
@@ -504,4 +679,21 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig)
batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_UNSNOOPABLES,
&bat_priv->mcast.num_want_all_unsnoopables,
BATADV_NO_FLAGS, orig->mcast_flags);
+ batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_IPV4,
+ &bat_priv->mcast.num_want_all_ipv4,
+ BATADV_NO_FLAGS, orig->mcast_flags);
+ batadv_mcast_counter_update(BATADV_MCAST_WANT_ALL_IPV6,
+ &bat_priv->mcast.num_want_all_ipv6,
+ BATADV_NO_FLAGS, orig->mcast_flags);
+
+ batadv_mcast_list_update(BATADV_MCAST_WANT_ALL_IPV4,
+ &orig->mcast_want_all_ipv4_node,
+ &bat_priv->mcast.want_all_ipv4_list,
+ &bat_priv->mcast.want_lists_lock,
+ BATADV_NO_FLAGS, orig->mcast_flags);
+ batadv_mcast_list_update(BATADV_MCAST_WANT_ALL_IPV6,
+ &orig->mcast_want_all_ipv6_node,
+ &bat_priv->mcast.want_all_ipv6_list,
+ &bat_priv->mcast.want_lists_lock,
+ BATADV_NO_FLAGS, orig->mcast_flags);
}
diff --git a/multicast.h b/multicast.h
index e26f146..3452077 100644
--- a/multicast.h
+++ b/multicast.h
@@ -39,7 +39,8 @@ enum batadv_forw_mode {
void batadv_mcast_mla_update(struct batadv_priv *bat_priv);

enum batadv_forw_mode
-batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv);
+batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv,
+ struct hlist_head **want_all_list);

int batadv_mcast_init(struct batadv_priv *bat_priv);

@@ -47,6 +48,9 @@ void batadv_mcast_free(struct batadv_priv *bat_priv);

void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node);

+struct batadv_orig_node *
+batadv_mcast_want_all_node_get(struct hlist_head *want_all_list,
+ struct batadv_priv *bat_priv);
#else

static inline void batadv_mcast_mla_update(struct batadv_priv *bat_priv)
@@ -55,7 +59,8 @@ static inline void batadv_mcast_mla_update(struct batadv_priv *bat_priv)
}

static inline enum batadv_forw_mode
-batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv)
+batadv_mcast_forw_mode(struct sk_buff *skb, struct batadv_priv *bat_priv,
+ struct hlist_head **want_all_list)
{
return BATADV_FORW_ALL;
}
@@ -75,6 +80,12 @@ static inline void batadv_mcast_purge_orig(struct batadv_orig_node *orig_node)
return;
}

+static inline struct batadv_orig_node *
+batadv_mcast_want_all_node_get(struct hlist_head *want_all_list,
+ struct batadv_priv *bat_priv)
+{
+ return NULL;
+}
#endif /* CONFIG_BATMAN_ADV_MCAST */

#endif /* _NET_BATMAN_ADV_MULTICAST_H_ */
diff --git a/packet.h b/packet.h
index 5fc795f..9a7919d 100644
--- a/packet.h
+++ b/packet.h
@@ -95,9 +95,13 @@ enum batadv_icmp_packettype {
* enum batadv_mcast_flags - flags for multicast capabilities and settings
* @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
+ * @BATADV_MCAST_WANT_ALL_IPV6: we want all IPv6 multicast packets
*/
enum batadv_mcast_flags {
BATADV_MCAST_WANT_ALL_UNSNOOPABLES = BIT(0),
+ BATADV_MCAST_WANT_ALL_IPV4 = BIT(1),
+ BATADV_MCAST_WANT_ALL_IPV6 = BIT(2),
};

/* tt data subtypes */
diff --git a/send.c b/send.c
index c83be5e..3d881ba 100644
--- a/send.c
+++ b/send.c
@@ -29,6 +29,7 @@
#include "originator.h"
#include "network-coding.h"
#include "fragmentation.h"
+#include "multicast.h"

static void batadv_send_outstanding_bcast_packet(struct work_struct *work);

@@ -353,6 +354,28 @@ int batadv_send_skb_via_gw(struct batadv_priv *bat_priv, struct sk_buff *skb,
orig_node, vid);
}

+/**
+ * batadv_send_skb_via_mcast - send an skb to a node with a WANT_ALL flag
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: payload to send
+ * @vid: the vid to be used to search the translation table
+ * @want_all_list: a list of originators with a WANT_ALL flag
+ *
+ * Get an originator node from the want_all_list. Wrap the given skb into a
+ * batman-adv unicast header and send this frame to this node.
+ */
+int batadv_send_skb_via_mcast(struct batadv_priv *bat_priv,
+ struct sk_buff *skb, unsigned short vid,
+ struct hlist_head *want_all_list)
+
+{
+ struct batadv_orig_node *orig_node;
+
+ orig_node = batadv_mcast_want_all_node_get(want_all_list, bat_priv);
+ return batadv_send_skb_unicast(bat_priv, skb, BATADV_UNICAST, 0,
+ orig_node, vid);
+}
+
void batadv_schedule_bat_ogm(struct batadv_hard_iface *hard_iface)
{
struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
diff --git a/send.h b/send.h
index aa2e253..3a6365f 100644
--- a/send.h
+++ b/send.h
@@ -43,6 +43,9 @@ int batadv_send_skb_via_tt_generic(struct batadv_priv *bat_priv,
int packet_subtype, unsigned short vid);
int batadv_send_skb_via_gw(struct batadv_priv *bat_priv, struct sk_buff *skb,
unsigned short vid);
+int batadv_send_skb_via_mcast(struct batadv_priv *bat_priv,
+ struct sk_buff *skb, unsigned short vid,
+ struct hlist_head *want_all_list);

/**
* batadv_send_skb_via_tt - send an skb via TT lookup
diff --git a/soft-interface.c b/soft-interface.c
index 2967a43..3f1700c 100644
--- a/soft-interface.c
+++ b/soft-interface.c
@@ -159,6 +159,7 @@ static int batadv_interface_tx(struct sk_buff *skb,
struct batadv_hard_iface *primary_if = NULL;
struct batadv_bcast_packet *bcast_packet;
__be16 ethertype = htons(ETH_P_BATMAN);
+ struct hlist_head *want_all_list = NULL;
static const uint8_t stp_addr[ETH_ALEN] = {0x01, 0x80, 0xC2, 0x00,
0x00, 0x00};
static const uint8_t ectp_addr[ETH_ALEN] = {0xCF, 0x00, 0x00, 0x00,
@@ -248,7 +249,8 @@ static int batadv_interface_tx(struct sk_buff *skb,
ethhdr = (struct ethhdr *)skb->data;

if (do_bcast && !is_broadcast_ether_addr(ethhdr->h_dest)) {
- mode = batadv_mcast_forw_mode(skb, bat_priv);
+ mode = batadv_mcast_forw_mode(skb, bat_priv,
+ &want_all_list);
if (mode == BATADV_FORW_NONE)
goto dropped;

@@ -315,6 +317,9 @@ static int batadv_interface_tx(struct sk_buff *skb,

if (forw_to_gw)
ret = batadv_send_skb_via_gw(bat_priv, skb, vid);
+ else if (want_all_list)
+ ret = batadv_send_skb_via_mcast(bat_priv, skb, vid,
+ want_all_list);
else
ret = batadv_send_skb_via_tt(bat_priv, skb, vid);

@@ -678,6 +683,8 @@ static int batadv_softif_init_late(struct net_device *dev)
atomic_set(&bat_priv->multicast_mode, 1);
atomic_set(&bat_priv->mcast.num_disabled, 0);
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);
#endif
atomic_set(&bat_priv->gw_mode, BATADV_GW_MODE_OFF);
atomic_set(&bat_priv->gw_sel_class, 20);
diff --git a/types.h b/types.h
index 1ce1793..9625d93 100644
--- a/types.h
+++ b/types.h
@@ -145,6 +145,8 @@ struct batadv_orig_node_vlan {
* @bcast_seqno_reset: time when the broadcast seqno window was reset
* @batman_seqno_reset: time when the batman seqno window was reset
* @mcast_flags: multicast flags announced by the orig node
+ * @mcast_want_all_ipv4_node: a list node for the mcast.want_all_ipv4 list
+ * @mcast_want_all_ipv6_node: a list node for the mcast.want_all_ipv6 list
* @capabilities: announced capabilities of this originator
* @last_ttvn: last seen translation table version number
* @tt_buff: last tt changeset this node received from the orig node
@@ -197,6 +199,8 @@ struct batadv_orig_node {
unsigned long batman_seqno_reset;
#ifdef CONFIG_BATMAN_ADV_MCAST
int mcast_flags;
+ struct hlist_node mcast_want_all_ipv4_node;
+ struct hlist_node mcast_want_all_ipv6_node;
#endif
uint8_t capabilities;
atomic_t last_ttvn;
@@ -548,15 +552,27 @@ struct batadv_priv_dat {
/**
* struct batadv_priv_mcast - per mesh interface mcast data
* @mla_list: list of multicast addresses we are currently announcing via TT
+ * @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
* @flags: the flags we have last sent in our mcast tvlv
* @num_disabled: number of nodes that have no mcast tvlv
* @num_want_all_unsnoopables: number of nodes wanting unsnoopable IP traffic
+ * @num_want_all_ipv4: counter for items in want_all_ipv4_list
+ * @num_want_all_ipv6: counter for items in want_all_ipv6_list
+ * @want_lists_lock: lock for protecting modifications to mcast want lists
+ * (traversals are rcu-locked)
*/
struct batadv_priv_mcast {
struct hlist_head mla_list;
+ struct hlist_head want_all_ipv4_list;
+ struct hlist_head want_all_ipv6_list;
int flags;
atomic_t num_disabled;
atomic_t num_want_all_unsnoopables;
+ atomic_t num_want_all_ipv4;
+ atomic_t num_want_all_ipv6;
+ /* protects want_all_ipv4_list & want_all_ipv6_list */
+ spinlock_t want_lists_lock;
};
#endif

--
1.7.10.4