Commit 766b5ed1 authored by daniel's avatar daniel Committed by Ben Hutchings

Bridge: Fix ipv6 mc snooping if bridge has no ipv6 address

commit 0888d5f3 upstream.

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: d1d81d4c ("bridge: check return value of ipv6_dev_get_saddr()")
Signed-off-by: default avatarDaniel Danzberger <daniel@dd-wrt.com>
Acked-by: default avatarLinus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 93917b05
...@@ -452,8 +452,11 @@ static struct sk_buff *br_ip6_multicast_alloc_query(struct net_bridge *br, ...@@ -452,8 +452,11 @@ 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, if (ipv6_dev_get_saddr(dev_net(br->dev), br->dev, &ip6h->daddr, 0,
&ip6h->saddr)) { &ip6h->saddr)) {
kfree_skb(skb); kfree_skb(skb);
br->has_ipv6_addr = 0;
return NULL; return NULL;
} }
br->has_ipv6_addr = 1;
ipv6_eth_mc_map(&ip6h->daddr, eth->h_dest); ipv6_eth_mc_map(&ip6h->daddr, eth->h_dest);
hopopt = (u8 *)(ip6h + 1); hopopt = (u8 *)(ip6h + 1);
...@@ -1869,6 +1872,7 @@ void br_multicast_init(struct net_bridge *br) ...@@ -1869,6 +1872,7 @@ void br_multicast_init(struct net_bridge *br)
br->ip6_other_query.delay_time = 0; br->ip6_other_query.delay_time = 0;
br->ip6_querier.port = NULL; br->ip6_querier.port = NULL;
#endif #endif
br->has_ipv6_addr = 1;
spin_lock_init(&br->multicast_lock); spin_lock_init(&br->multicast_lock);
setup_timer(&br->multicast_router_timer, setup_timer(&br->multicast_router_timer,
......
...@@ -261,6 +261,7 @@ struct net_bridge ...@@ -261,6 +261,7 @@ struct net_bridge
u8 multicast_disabled:1; u8 multicast_disabled:1;
u8 multicast_querier:1; u8 multicast_querier:1;
u8 multicast_query_use_ifaddr:1; u8 multicast_query_use_ifaddr:1;
u8 has_ipv6_addr:1;
u32 hash_elasticity; u32 hash_elasticity;
u32 hash_max; u32 hash_max;
...@@ -497,10 +498,22 @@ static inline bool br_multicast_is_router(struct net_bridge *br) ...@@ -497,10 +498,22 @@ static inline bool br_multicast_is_router(struct net_bridge *br)
static inline bool static inline bool
__br_multicast_querier_exists(struct net_bridge *br, __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) && 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, static inline bool br_multicast_querier_exists(struct net_bridge *br,
...@@ -508,10 +521,12 @@ static inline bool br_multicast_querier_exists(struct net_bridge *br, ...@@ -508,10 +521,12 @@ static inline bool br_multicast_querier_exists(struct net_bridge *br,
{ {
switch (eth->h_proto) { switch (eth->h_proto) {
case (htons(ETH_P_IP)): 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) #if IS_ENABLED(CONFIG_IPV6)
case (htons(ETH_P_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 #endif
default: default:
return false; return false;
......
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