bridge: Snoop Multicast Router Advertisements

When multiple multicast routers are present in a broadcast domain then
only one of them will be detectable via IGMP/MLD query snooping. The
multicast router with the lowest IP address will become the selected and
active querier while all other multicast routers will then refrain from
sending queries.

To detect such rather silent multicast routers, too, RFC4286
("Multicast Router Discovery") provides a standardized protocol to
detect multicast routers for multicast snooping switches.

This patch implements the necessary MRD Advertisement message parsing
and after successful processing adds such routers to the internal
multicast router list.

Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index daf11dcb0f70..20d523ee2fec 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -229,6 +229,7 @@ void ipv6_mc_unmap(struct inet6_dev *idev);
 void ipv6_mc_remap(struct inet6_dev *idev);
 void ipv6_mc_init_dev(struct inet6_dev *idev);
 void ipv6_mc_destroy_dev(struct inet6_dev *idev);
+int ipv6_mc_check_icmpv6(struct sk_buff *skb);
 int ipv6_mc_check_mld(struct sk_buff *skb);
 void addrconf_dad_failure(struct sk_buff *skb, struct inet6_ifaddr *ifp);
 
@@ -499,6 +500,20 @@ static inline bool ipv6_addr_is_solict_mult(const struct in6_addr *addr)
 #endif
 }
 
+static inline bool ipv6_addr_is_all_snoopers(const struct in6_addr *addr)
+{
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
+	__be64 *p = (__be64 *)addr;
+
+	return ((p[0] ^ cpu_to_be64(0xff02000000000000UL)) |
+		(p[1] ^ cpu_to_be64(0x6a))) == 0UL;
+#else
+	return ((addr->s6_addr32[0] ^ htonl(0xff020000)) |
+		addr->s6_addr32[1] | addr->s6_addr32[2] |
+		(addr->s6_addr32[3] ^ htonl(0x0000006a))) == 0;
+#endif
+}
+
 #ifdef CONFIG_PROC_FS
 int if6_proc_init(void);
 void if6_proc_exit(void);