batman-adv: Add IPv4 link-local/IPv6-ll-all-nodes multicast support
With this patch a node may additionally perform the dropping or
unicasting behaviour for a link-local IPv4 and link-local-all-nodes
IPv6 multicast packet, too.
The extra counter and BATADV_MCAST_WANT_ALL_UNSNOOPABLES flag is needed
because with a future bridge snooping support integration a node with a
bridge on top of its soft interface is not able to reliably detect its
multicast listeners for IPv4 link-local and the IPv6
link-local-all-nodes addresses anymore (see RFC4541, section 2.1.2.2
and section 3).
Even though this new flag does make "no difference" now, it'll ensure
a seamless integration of multicast bridge support without needing to
break compatibility later.
Also note, that even with multicast bridge support it won't be possible
to optimize 224.0.0.x and ff02::1 towards nodes with bridges, they will
always receive these ranges.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 1d1627f..a4804fa 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -248,9 +248,48 @@
}
/**
+ * 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
+ *
+ * Checks whether the given IPv4 packet has the potential to be forwarded with a
+ * mode more optimal than classic flooding.
+ *
+ * If so then returns 0. Otherwise -EINVAL is returned or -ENOMEM in case of
+ * memory allocation failure.
+ */
+static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
+ struct sk_buff *skb,
+ bool *is_unsnoopable)
+{
+ struct iphdr *iphdr;
+
+ /* We might fail due to out-of-memory -> drop it */
+ if (!pskb_may_pull(skb, sizeof(struct ethhdr) + sizeof(*iphdr)))
+ return -ENOMEM;
+
+ 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;
+
+ return 0;
+}
+
+/**
* 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
*
* Checks whether the given IPv6 packet has the potential to be forwarded with a
* mode more optimal than classic flooding.
@@ -259,7 +298,8 @@
* of memory.
*/
static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ bool *is_unsnoopable)
{
struct ipv6hdr *ip6hdr;
@@ -279,7 +319,7 @@
* not snoopable (see RFC4541, section 3, paragraph 3)
*/
if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr))
- return -EINVAL;
+ *is_unsnoopable = true;
return 0;
}
@@ -288,6 +328,7 @@
* batadv_mcast_forw_mode_check - check for optimized forwarding potential
* @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
*
* Checks whether the given multicast ethernet frame has the potential to be
* forwarded with a mode more optimal than classic flooding.
@@ -296,7 +337,8 @@
* of memory.
*/
static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
- struct sk_buff *skb)
+ struct sk_buff *skb,
+ bool *is_unsnoopable)
{
struct ethhdr *ethhdr = eth_hdr(skb);
@@ -307,8 +349,12 @@
return -EINVAL;
switch (ntohs(ethhdr->h_proto)) {
+ case ETH_P_IP:
+ return batadv_mcast_forw_mode_check_ipv4(bat_priv, skb,
+ is_unsnoopable);
case ETH_P_IPV6:
- return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb);
+ return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb,
+ is_unsnoopable);
default:
return -EINVAL;
}
@@ -331,6 +377,33 @@
}
/**
+ * batadv_mcast_want_forw_unsnoop_node_get - get a node with an unsnoopable flag
+ * @bat_priv: the bat priv with all the soft interface information
+ *
+ * Returns an orig_node which has the BATADV_MCAST_WANT_ALL_UNSNOOPABLES flag
+ * set and increases its refcount.
+ */
+static struct batadv_orig_node *
+batadv_mcast_forw_unsnoop_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_unsnoopables_list,
+ mcast_want_all_unsnoopables_node) {
+ if (!atomic_inc_not_zero(&orig_node->refcount))
+ continue;
+
+ orig_node = tmp_orig_node;
+ break;
+ }
+ rcu_read_unlock();
+
+ return orig_node;
+}
+
+/**
* batadv_mcast_forw_mode - check on how to forward a multicast packet
* @bat_priv: the bat priv with all the soft interface information
* @skb: The multicast packet to check
@@ -344,10 +417,11 @@
batadv_mcast_forw_mode(struct batadv_priv *bat_priv, struct sk_buff *skb,
struct batadv_orig_node **orig)
{
+ int ret, tt_count, unsnoop_count, total_count;
+ bool is_unsnoopable = false;
struct ethhdr *ethhdr;
- int ret, tt_count;
- ret = batadv_mcast_forw_mode_check(bat_priv, skb);
+ ret = batadv_mcast_forw_mode_check(bat_priv, skb, &is_unsnoopable);
if (ret == -ENOMEM)
return BATADV_FORW_NONE;
else if (ret < 0)
@@ -357,10 +431,18 @@
tt_count = batadv_tt_global_hash_count(bat_priv, ethhdr->h_dest,
BATADV_NO_FLAGS);
+ unsnoop_count = !is_unsnoopable ? 0 :
+ atomic_read(&bat_priv->mcast.num_want_all_unsnoopables);
- switch (tt_count) {
+ total_count = tt_count + unsnoop_count;
+
+ switch (total_count) {
case 1:
- *orig = batadv_mcast_forw_tt_node_get(bat_priv, ethhdr);
+ if (tt_count)
+ *orig = batadv_mcast_forw_tt_node_get(bat_priv, ethhdr);
+ else if (unsnoop_count)
+ *orig = batadv_mcast_forw_unsnoop_node_get(bat_priv);
+
if (*orig)
return BATADV_FORW_SINGLE;
@@ -373,6 +455,39 @@
}
/**
+ * 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
+ * @mcast_flags: flags indicating the new multicast state
+ *
+ * If the BATADV_MCAST_WANT_ALL_UNSNOOPABLES flag of this originator,
+ * orig, has toggled then this method updates counter and list accordingly.
+ */
+static void batadv_mcast_want_unsnoop_update(struct batadv_priv *bat_priv,
+ struct batadv_orig_node *orig,
+ uint8_t mcast_flags)
+{
+ /* switched from flag unset to set */
+ if (mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES &&
+ !(orig->mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES)) {
+ atomic_inc(&bat_priv->mcast.num_want_all_unsnoopables);
+
+ spin_lock_bh(&bat_priv->mcast.want_lists_lock);
+ hlist_add_head_rcu(&orig->mcast_want_all_unsnoopables_node,
+ &bat_priv->mcast.want_all_unsnoopables_list);
+ spin_unlock_bh(&bat_priv->mcast.want_lists_lock);
+ /* switched from flag set to unset */
+ } else if (!(mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES) &&
+ orig->mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES) {
+ atomic_dec(&bat_priv->mcast.num_want_all_unsnoopables);
+
+ spin_lock_bh(&bat_priv->mcast.want_lists_lock);
+ hlist_del_rcu(&orig->mcast_want_all_unsnoopables_node);
+ spin_unlock_bh(&bat_priv->mcast.want_lists_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
@@ -416,6 +531,8 @@
(tvlv_value_len >= sizeof(mcast_flags)))
mcast_flags = *(uint8_t *)tvlv_value;
+ batadv_mcast_want_unsnoop_update(bat_priv, orig, mcast_flags);
+
orig->mcast_flags = mcast_flags;
}
@@ -452,4 +569,6 @@
if (!(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST))
atomic_dec(&bat_priv->mcast.num_disabled);
+
+ batadv_mcast_want_unsnoop_update(bat_priv, orig, BATADV_NO_FLAGS);
}