[5/6] batman-adv: Add IPv4 link-local/IPv6-ll-all-nodes multicast support
Commit Message
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 will need only
one node with a bridge to disable optimizations for link-local IPv4
and IPv6-link-local-all-nodes multicast, resulting in flooding all
these packets again. So the 224.0.0.x address range and the ff02::1
address will never be a safe choice for multicast streaming etc. if
you do not control every node.
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
main.h | 1 +
multicast.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++-
packet.h | 9 +++++++++
soft-interface.c | 1 +
types.h | 2 ++
5 files changed, 64 insertions(+), 1 deletion(-)
@@ -177,6 +177,7 @@ enum batadv_uev_type {
#include <linux/slab.h>
#include <net/sock.h> /* struct sock */
#include <net/addrconf.h> /* ipv6 address stuff */
+#include <linux/ip.h>
#include <net/rtnetlink.h>
#include <linux/jiffies.h>
#include <linux/seq_file.h>
@@ -272,6 +272,44 @@ out:
}
/**
+ * 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
+ *
+ * Check whether the given IPv4 packet has the potential to
+ * be forwarded with a mode more optimal than classic flooding.
+ *
+ * If so then return 0. Otherwise -EINVAL is returned or -ENOMEM if we are
+ * out of memory.
+ */
+static int batadv_mcast_forw_mode_check_ipv4(struct batadv_priv *bat_priv,
+ struct sk_buff *skb)
+{
+ 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;
+
+ /* With one bridge involved, we cannot be certain about
+ * link-local multicast listener announcements anymore
+ * (see RFC4541, section 2.1.2.2)
+ */
+ if (atomic_read(&bat_priv->mcast.num_want_all_unsnoopables))
+ return -EINVAL;
+
+ 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
@@ -304,7 +342,8 @@ static int batadv_mcast_forw_mode_check_ipv6(struct batadv_priv *bat_priv,
* link-local-all-nodes multicast listener announcements anymore
* (see RFC4541, section 3, paragraph 3)
*/
- if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr))
+ if (ipv6_addr_is_ll_all_nodes(&ip6hdr->daddr) &&
+ atomic_read(&bat_priv->mcast.num_want_all_unsnoopables))
return -EINVAL;
return 0;
@@ -333,6 +372,8 @@ static int batadv_mcast_forw_mode_check(struct batadv_priv *bat_priv,
return -EINVAL;
switch (ntohs(ethhdr->h_proto)) {
+ case ETH_P_IP:
+ return batadv_mcast_forw_mode_check_ipv4(bat_priv, skb);
case ETH_P_IPV6:
return batadv_mcast_forw_mode_check_ipv6(bat_priv, skb);
default:
@@ -416,6 +457,13 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
(tvlv_value_len >= sizeof(mcast_flags)))
mcast_flags = *(uint8_t *)tvlv_value;
+ 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);
+ 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);
+
orig->mcast_flags = mcast_flags;
}
@@ -452,4 +500,6 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig)
if (!(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST))
atomic_dec(&bat_priv->mcast.num_disabled);
+ if (orig->mcast_flags & BATADV_MCAST_WANT_ALL_UNSNOOPABLES)
+ atomic_dec(&bat_priv->mcast.num_want_all_unsnoopables);
}
@@ -89,6 +89,15 @@ enum batadv_icmp_packettype {
BATADV_PARAMETER_PROBLEM = 12,
};
+/**
+ * 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
+ */
+enum batadv_mcast_flags {
+ BATADV_MCAST_WANT_ALL_UNSNOOPABLES = BIT(0),
+};
+
/* tt data subtypes */
#define BATADV_TT_DATA_TYPE_MASK 0x0F
@@ -707,6 +707,7 @@ static int batadv_softif_init_late(struct net_device *dev)
bat_priv->mcast.flags = BATADV_NO_FLAGS;
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);
#endif
atomic_set(&bat_priv->gw_mode, BATADV_GW_MODE_OFF);
atomic_set(&bat_priv->gw_sel_class, 20);
@@ -622,12 +622,14 @@ struct batadv_priv_dat {
* @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
+ * @num_want_all_unsnoopables: number of nodes wanting unsnoopable IP traffic
*/
struct batadv_priv_mcast {
struct hlist_head mla_list;
uint8_t flags;
bool enabled;
atomic_t num_disabled;
+ atomic_t num_want_all_unsnoopables;
};
#endif