ipv6: ip6mr: support multiple tables

This patch adds support for multiple independant multicast routing instances,
named "tables".

Userspace multicast routing daemons can bind to a specific table instance by
issuing a setsockopt call using a new option MRT6_TABLE. The table number is
stored in the raw socket data and affects all following ip6mr setsockopt(),
getsockopt() and ioctl() calls. By default, a single table (RT6_TABLE_DFLT)
is created with a default routing rule pointing to it. Newly created pim6reg
devices have the table number appended ("pim6regX"), with the exception of
devices created in the default table, which are named just "pim6reg" for
compatibility reasons.

Packets are directed to a specific table instance using routing rules,
similar to how regular routing rules work. Currently iif, oif and mark
are supported as keys, source and destination addresses could be supported
additionally.

Example usage:

- bind pimd/xorp/... to a specific table:

uint32_t table = 123;
setsockopt(fd, SOL_IPV6, MRT6_TABLE, &table, sizeof(table));

- create routing rules directing packets to the new table:

# ip -6 mrule add iif eth0 lookup 123
# ip -6 mrule add oif eth0 lookup 123

Signed-off-by: Patrick McHardy <kaber@trash.net>

3 files changed, 14 insertions, 5 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 0e269038bb38..99e1ab7e3eec 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -383,6 +383,7 @@ struct raw6_sock {
         __u32                   checksum;       /* perform checksum */
         __u32                   offset;         /* checksum offset  */
         struct icmp6_filter     filter;
+        __u32                   ip6mr_table;
         /* ipv6_pinfo has to be the last member of raw6_sock, see inet6_sk_generic */
         struct ipv6_pinfo       inet6;
 };
diff --git a/include/linux/mroute6.h b/include/linux/mroute6.h
index 0370dd4f2389..6091ab77f388 100644
--- a/include/linux/mroute6.h
+++ b/include/linux/mroute6.h
@@ -24,7 +24,8 @@
 #define MRT6_DEL_MFC    (MRT6_BASE+5)   /* Delete a multicast forwarding entry  */
 #define MRT6_VERSION    (MRT6_BASE+6)   /* Get the kernel multicast version     */
 #define MRT6_ASSERT     (MRT6_BASE+7)   /* Activate PIM assert mode             */
-#define MRT6_PIM        (MRT6_BASE+8)   /* enable PIM code      */
+#define MRT6_PIM        (MRT6_BASE+8)   /* enable PIM code                      */
+#define MRT6_TABLE      (MRT6_BASE+9)   /* Specify mroute table ID              */
 
 #define SIOCGETMIFCNT_IN6       SIOCPROTOPRIVATE        /* IP protocol privates */
 #define SIOCGETSGCNT_IN6        (SIOCPROTOPRIVATE+1)
@@ -229,11 +230,17 @@ extern int ip6mr_get_route(struct net *net, struct sk_buff *skb,
                            struct rtmsg *rtm, int nowait);
 
 #ifdef CONFIG_IPV6_MROUTE
-extern struct sock *mroute6_socket(struct net *net);
+extern struct sock *mroute6_socket(struct net *net, struct sk_buff *skb);
 extern int ip6mr_sk_done(struct sock *sk);
 #else
-static inline struct sock *mroute6_socket(struct net *net) { return NULL; }
-static inline int ip6mr_sk_done(struct sock *sk) { return 0; }
+static inline struct sock *mroute6_socket(struct net *net, struct sk_buff *skb)
+{
+        return NULL;
+}
+static inline int ip6mr_sk_done(struct sock *sk)
+{
+        return 0;
+}
 #endif
 #endif
 
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index 5a42c36cb6aa..fbc8cb0d48c3 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -11,7 +11,8 @@
  * families, values above 128 may be used arbitrarily.
  */
 #define RTNL_FAMILY_IPMR                128
-#define RTNL_FAMILY_MAX                 128
+#define RTNL_FAMILY_IP6MR               129
+#define RTNL_FAMILY_MAX                 129
 
 /****
  *              Routing/neighbour discovery messages.