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bridge: adhere to querier election mechanism specified by RFCs
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MLDv1 (RFC2710 section 6), MLDv2 (RFC3810 section 7.6.2), IGMPv2
(RFC2236 section 3) and IGMPv3 (RFC3376 section 6.6.2) specify that the
querier with lowest source address shall become the selected
querier.

So far the bridge stopped its querier as soon as it heard another
querier regardless of its source address. This results in the "wrong"
querier potentially becoming the active querier or a potential,
unnecessary querying delay.

With this patch the bridge memorizes the source address of the currently
selected querier and ignores queries from queriers with a higher source
address than the currently selected one. This slight optimization is
supposed to make it more RFC compliant (but is rather uncritical and
therefore probably not necessary to be queued for stable kernels).

Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Linus Lüssing authored and David S. Miller committed Jun 11, 2014
1 parent 90010b3 commit dc4eb53
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Showing 2 changed files with 95 additions and 13 deletions.
101 changes: 88 additions & 13 deletions net/bridge/br_multicast.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -789,6 +789,18 @@ static void br_ip6_multicast_querier_expired(unsigned long data)
}
#endif

static void br_multicast_select_own_querier(struct net_bridge *br,
struct br_ip *ip,
struct sk_buff *skb)
{
if (ip->proto == htons(ETH_P_IP))
br->ip4_querier.addr.u.ip4 = ip_hdr(skb)->saddr;
#if IS_ENABLED(CONFIG_IPV6)
else
br->ip6_querier.addr.u.ip6 = ipv6_hdr(skb)->saddr;
#endif
}

static void __br_multicast_send_query(struct net_bridge *br,
struct net_bridge_port *port,
struct br_ip *ip)
Expand All @@ -804,8 +816,10 @@ static void __br_multicast_send_query(struct net_bridge *br,
skb->dev = port->dev;
NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
dev_queue_xmit);
} else
} else {
br_multicast_select_own_querier(br, ip, skb);
netif_rx(skb);
}
}

static void br_multicast_send_query(struct net_bridge *br,
Expand Down Expand Up @@ -1065,6 +1079,62 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br,
}
#endif

static bool br_ip4_multicast_select_querier(struct net_bridge *br,
__be32 saddr)
{
if (!timer_pending(&br->ip4_own_query.timer) &&
!timer_pending(&br->ip4_other_query.timer))
goto update;

if (!br->ip4_querier.addr.u.ip4)
goto update;

if (ntohl(saddr) <= ntohl(br->ip4_querier.addr.u.ip4))
goto update;

return false;

update:
br->ip4_querier.addr.u.ip4 = saddr;

return true;
}

#if IS_ENABLED(CONFIG_IPV6)
static bool br_ip6_multicast_select_querier(struct net_bridge *br,
struct in6_addr *saddr)
{
if (!timer_pending(&br->ip6_own_query.timer) &&
!timer_pending(&br->ip6_other_query.timer))
goto update;

if (ipv6_addr_cmp(saddr, &br->ip6_querier.addr.u.ip6) <= 0)
goto update;

return false;

update:
br->ip6_querier.addr.u.ip6 = *saddr;

return true;
}
#endif

static bool br_multicast_select_querier(struct net_bridge *br,
struct br_ip *saddr)
{
switch (saddr->proto) {
case htons(ETH_P_IP):
return br_ip4_multicast_select_querier(br, saddr->u.ip4);
#if IS_ENABLED(CONFIG_IPV6)
case htons(ETH_P_IPV6):
return br_ip6_multicast_select_querier(br, &saddr->u.ip6);
#endif
}

return false;
}

static void
br_multicast_update_query_timer(struct net_bridge *br,
struct bridge_mcast_other_query *query,
Expand Down Expand Up @@ -1127,15 +1197,13 @@ static void br_multicast_mark_router(struct net_bridge *br,
static void br_multicast_query_received(struct net_bridge *br,
struct net_bridge_port *port,
struct bridge_mcast_other_query *query,
int saddr,
bool is_general_query,
struct br_ip *saddr,
unsigned long max_delay)
{
if (saddr && is_general_query)
br_multicast_update_query_timer(br, query, max_delay);
else if (timer_pending(&query->timer))
if (!br_multicast_select_querier(br, saddr))
return;

br_multicast_update_query_timer(br, query, max_delay);
br_multicast_mark_router(br, port);
}

Expand All @@ -1150,6 +1218,7 @@ static int br_ip4_multicast_query(struct net_bridge *br,
struct igmpv3_query *ih3;
struct net_bridge_port_group *p;
struct net_bridge_port_group __rcu **pp;
struct br_ip saddr;
unsigned long max_delay;
unsigned long now = jiffies;
__be32 group;
Expand Down Expand Up @@ -1191,11 +1260,14 @@ static int br_ip4_multicast_query(struct net_bridge *br,
goto out;
}

br_multicast_query_received(br, port, &br->ip4_other_query,
!!iph->saddr, !group, max_delay);
if (!group) {
saddr.proto = htons(ETH_P_IP);
saddr.u.ip4 = iph->saddr;

if (!group)
br_multicast_query_received(br, port, &br->ip4_other_query,
&saddr, max_delay);
goto out;
}

mp = br_mdb_ip4_get(mlock_dereference(br->mdb, br), group, vid);
if (!mp)
Expand Down Expand Up @@ -1235,6 +1307,7 @@ static int br_ip6_multicast_query(struct net_bridge *br,
struct mld2_query *mld2q;
struct net_bridge_port_group *p;
struct net_bridge_port_group __rcu **pp;
struct br_ip saddr;
unsigned long max_delay;
unsigned long now = jiffies;
const struct in6_addr *group = NULL;
Expand Down Expand Up @@ -1283,12 +1356,14 @@ static int br_ip6_multicast_query(struct net_bridge *br,
goto out;
}

br_multicast_query_received(br, port, &br->ip6_other_query,
!ipv6_addr_any(&ip6h->saddr),
is_general_query, max_delay);
if (is_general_query) {
saddr.proto = htons(ETH_P_IPV6);
saddr.u.ip6 = ip6h->saddr;

if (!group)
br_multicast_query_received(br, port, &br->ip6_other_query,
&saddr, max_delay);
goto out;
}

mp = br_mdb_ip6_get(mlock_dereference(br->mdb, br), group, vid);
if (!mp)
Expand Down
7 changes: 7 additions & 0 deletions net/bridge/br_private.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,11 @@ struct bridge_mcast_other_query {
struct timer_list timer;
unsigned long delay_time;
};

/* selected querier */
struct bridge_mcast_querier {
struct br_ip addr;
};
#endif

struct net_port_vlans {
Expand Down Expand Up @@ -284,9 +289,11 @@ struct net_bridge
struct timer_list multicast_router_timer;
struct bridge_mcast_other_query ip4_other_query;
struct bridge_mcast_own_query ip4_own_query;
struct bridge_mcast_querier ip4_querier;
#if IS_ENABLED(CONFIG_IPV6)
struct bridge_mcast_other_query ip6_other_query;
struct bridge_mcast_own_query ip6_own_query;
struct bridge_mcast_querier ip6_querier;
#endif /* IS_ENABLED(CONFIG_IPV6) */
#endif

Expand Down

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