Merge branch 'bridge-mrd'

Linus Lüssing says:

====================
bridge: implement Multicast Router Discovery (RFC4286)

This patchset adds initial Multicast Router Discovery support to
the Linux bridge (RFC4286). With MRD it is possible to detect multicast
routers and mark bridge ports and forward multicast packets to such routers
accordingly.

So far, multicast routers are detected via IGMP/MLD queries and PIM
messages in the Linux bridge. As there is only one active, selected
querier at a time RFC4541 ("Considerations for Internet Group Management
Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping
Switches") section 2.1.1.a) recommends snooping Multicast Router
Advertisements as provided by MRD (RFC4286).

The first two patches are refactoring some existing code which is reused
for parsing the Multicast Router Advertisements later in the fourth
patch. The third patch lets the bridge join the all-snoopers multicast
address to be able to reliably receive the Multicast Router
Advertisements.

What is not implemented yet from RFC4286 yet:

* Sending Multicast Router Solicitations:
  -> RFC4286: "[...] may be sent when [...] an interface is
     (re-)initialized [or] MRD is enabled"
* Snooping Multicast Router Terminations:
  -> currently this only relies on our own timeouts
* Adjusting timeouts with the values provided in the announcements

Changes in v2:

* rebased to current net-next/master (no conflicts/changes)
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 26 insertions, 1 deletions

diff --git a/include/linux/igmp.h b/include/linux/igmp.h
index 119f53941c12..8b4348f69bc5 100644
--- a/include/linux/igmp.h
+++ b/include/linux/igmp.h
@@ -18,6 +18,7 @@
 #include <linux/skbuff.h>
 #include <linux/timer.h>
 #include <linux/in.h>
+#include <linux/ip.h>
 #include <linux/refcount.h>
 #include <uapi/linux/igmp.h>
 
@@ -106,6 +107,14 @@ struct ip_mc_list {
 #define IGMPV3_QQIC(value) IGMPV3_EXP(0x80, 4, 3, value)
 #define IGMPV3_MRC(value) IGMPV3_EXP(0x80, 4, 3, value)
 
+static inline int ip_mc_may_pull(struct sk_buff *skb, unsigned int len)
+{
+	if (skb_transport_offset(skb) + ip_transport_len(skb) < len)
+		return -EINVAL;
+
+	return pskb_may_pull(skb, len);
+}
+
 extern int ip_check_mc_rcu(struct in_device *dev, __be32 mc_addr, __be32 src_addr, u8 proto);
 extern int igmp_rcv(struct sk_buff *);
 extern int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr);
@@ -130,6 +139,6 @@ extern void ip_mc_unmap(struct in_device *);
 extern void ip_mc_remap(struct in_device *);
 extern void ip_mc_dec_group(struct in_device *in_dev, __be32 addr);
 extern void ip_mc_inc_group(struct in_device *in_dev, __be32 addr);
-int ip_mc_check_igmp(struct sk_buff *skb, struct sk_buff **skb_trimmed);
+int ip_mc_check_igmp(struct sk_buff *skb);
 
 #endif
diff --git a/include/linux/in.h b/include/linux/in.h
index 31b493734763..435e7f2a513a 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -60,6 +60,11 @@ static inline bool ipv4_is_lbcast(__be32 addr)
 	return addr == htonl(INADDR_BROADCAST);
 }
 
+static inline bool ipv4_is_all_snoopers(__be32 addr)
+{
+	return addr == htonl(INADDR_ALLSNOOPERS_GROUP);
+}
+
 static inline bool ipv4_is_zeronet(__be32 addr)
 {
 	return (addr & htonl(0xff000000)) == htonl(0x00000000);
diff --git a/include/linux/ip.h b/include/linux/ip.h
index 492bc6513533..482b7b7c9f30 100644
--- a/include/linux/ip.h
+++ b/include/linux/ip.h
@@ -34,4 +34,9 @@ static inline struct iphdr *ipip_hdr(const struct sk_buff *skb)
 {
 	return (struct iphdr *)skb_transport_header(skb);
 }
+
+static inline unsigned int ip_transport_len(const struct sk_buff *skb)
+{
+	return ntohs(ip_hdr(skb)->tot_len) - skb_network_header_len(skb);
+}
 #endif	/* _LINUX_IP_H */
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 495e834c1367..6d45ce784bea 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -104,6 +104,12 @@ static inline struct ipv6hdr *ipipv6_hdr(const struct sk_buff *skb)
 	return (struct ipv6hdr *)skb_transport_header(skb);
 }
 
+static inline unsigned int ipv6_transport_len(const struct sk_buff *skb)
+{
+	return ntohs(ipv6_hdr(skb)->payload_len) + sizeof(struct ipv6hdr) -
+	       skb_network_header_len(skb);
+}
+
 /* 
    This structure contains results of exthdrs parsing
    as offsets from skb->nh.