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-rw-r--r--target/linux/generic/patches-4.4/646-bridge_fix_ipv6_mc_snooping_if_bridge_has_no_ipv6_address.patch113
1 files changed, 113 insertions, 0 deletions
diff --git a/target/linux/generic/patches-4.4/646-bridge_fix_ipv6_mc_snooping_if_bridge_has_no_ipv6_address.patch b/target/linux/generic/patches-4.4/646-bridge_fix_ipv6_mc_snooping_if_bridge_has_no_ipv6_address.patch
new file mode 100644
index 0000000000..4388cda6ef
--- /dev/null
+++ b/target/linux/generic/patches-4.4/646-bridge_fix_ipv6_mc_snooping_if_bridge_has_no_ipv6_address.patch
@@ -0,0 +1,113 @@
+From: daniel <daniel@dd-wrt.com>
+Date: Fri, 24 Jun 2016 12:35:18 +0200
+Subject: [PATCH] Bridge: Fix ipv6 mc snooping if bridge has no ipv6 address
+
+The bridge is falsly dropping ipv6 mulitcast packets if there is:
+ 1. No ipv6 address assigned on the brigde.
+ 2. No external mld querier present.
+ 3. The internal querier enabled.
+
+When the bridge fails to build mld queries, because it has no
+ipv6 address, it slilently returns, but keeps the local querier enabled.
+This specific case causes confusing packet loss.
+
+Ipv6 multicast snooping can only work if:
+ a) An external querier is present
+ OR
+ b) The bridge has an ipv6 address an is capable of sending own queries
+
+Otherwise it has to forward/flood the ipv6 multicast traffic,
+because snooping cannot work.
+
+This patch fixes the issue by adding a flag to the bridge struct that
+indicates that there is currently no ipv6 address assinged to the bridge
+and returns a false state for the local querier in
+__br_multicast_querier_exists().
+
+Special thanks to Linus Lüssing.
+
+Fixes: d1d81d4c3dd8 ("bridge: check return value of ipv6_dev_get_saddr()")
+Signed-off-by: Daniel Danzberger <daniel@dd-wrt.com>
+Acked-by: Linus Lüssing <linus.luessing@c0d3.blue>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ net/bridge/br_multicast.c | 4 ++++
+ net/bridge/br_private.h | 23 +++++++++++++++++++----
+ 2 files changed, 23 insertions(+), 4 deletions(-)
+
+diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
+index c8c2a8a..d063a10 100644
+--- a/net/bridge/br_multicast.c
++++ b/net/bridge/br_multicast.c
+@@ -465,8 +465,11 @@ static struct sk_buff *br_ip6_multicast_alloc_query(struct net_bridge *br,
+ if (ipv6_dev_get_saddr(dev_net(br->dev), br->dev, &ip6h->daddr, 0,
+ &ip6h->saddr)) {
+ kfree_skb(skb);
++ br->has_ipv6_addr = 0;
+ return NULL;
+ }
++
++ br->has_ipv6_addr = 1;
+ ipv6_eth_mc_map(&ip6h->daddr, eth->h_dest);
+
+ hopopt = (u8 *)(ip6h + 1);
+@@ -1768,6 +1771,7 @@ void br_multicast_init(struct net_bridge *br)
+ br->ip6_other_query.delay_time = 0;
+ br->ip6_querier.port = NULL;
+ #endif
++ br->has_ipv6_addr = 1;
+
+ spin_lock_init(&br->multicast_lock);
+ setup_timer(&br->multicast_router_timer,
+diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
+index e24abfd..3dd7e2c 100644
+--- a/net/bridge/br_private.h
++++ b/net/bridge/br_private.h
+@@ -303,6 +303,7 @@ struct net_bridge
+ u8 multicast_disabled:1;
+ u8 multicast_querier:1;
+ u8 multicast_query_use_ifaddr:1;
++ u8 has_ipv6_addr:1;
+
+ u32 hash_elasticity;
+ u32 hash_max;
+@@ -577,10 +578,22 @@ static inline bool br_multicast_is_router(struct net_bridge *br)
+
+ static inline bool
+ __br_multicast_querier_exists(struct net_bridge *br,
+- struct bridge_mcast_other_query *querier)
++ struct bridge_mcast_other_query *querier,
++ const bool is_ipv6)
+ {
++ bool own_querier_enabled;
++
++ if (br->multicast_querier) {
++ if (is_ipv6 && !br->has_ipv6_addr)
++ own_querier_enabled = false;
++ else
++ own_querier_enabled = true;
++ } else {
++ own_querier_enabled = false;
++ }
++
+ return time_is_before_jiffies(querier->delay_time) &&
+- (br->multicast_querier || timer_pending(&querier->timer));
++ (own_querier_enabled || timer_pending(&querier->timer));
+ }
+
+ static inline bool br_multicast_querier_exists(struct net_bridge *br,
+@@ -588,10 +601,12 @@ static inline bool br_multicast_querier_exists(struct net_bridge *br,
+ {
+ switch (eth->h_proto) {
+ case (htons(ETH_P_IP)):
+- return __br_multicast_querier_exists(br, &br->ip4_other_query);
++ return __br_multicast_querier_exists(br,
++ &br->ip4_other_query, false);
+ #if IS_ENABLED(CONFIG_IPV6)
+ case (htons(ETH_P_IPV6)):
+- return __br_multicast_querier_exists(br, &br->ip6_other_query);
++ return __br_multicast_querier_exists(br,
++ &br->ip6_other_query, true);
+ #endif
+ default:
+ return false;