ipv6: fib: Add in-kernel notifications for route add / delete

As with IPv4, allow listeners of the FIB notification chain to receive
notifications whenever a route is added, replaced or deleted. This is
done by placing calls to the FIB notification chain in the two lowest
level functions that end up performing these operations - namely,
fib6_add_rt2node() and fib6_del_route().

Unlike IPv4, APPEND notifications aren't sent as the kernel doesn't
distinguish between "append" (NLM_F_CREATE|NLM_F_APPEND) and "prepend"
(NLM_F_CREATE). If NLM_F_EXCL isn't set, duplicate routes are always
added after the existing duplicate routes.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip6_fib.h

@@ -258,6 +258,11 @@ typedef struct rt6_info *(*pol_lookup_t)(struct net *,
 					 struct fib6_table *,
 					 struct flowi6 *, int);
 
+struct fib6_entry_notifier_info {
+	struct fib_notifier_info info; /* must be first */
+	struct rt6_info *rt;
+};
+
 /*
  *	exported functions
  */

net/ipv6/ip6_fib.c

@@ -33,6 +33,7 @@
 #include <net/ndisc.h>
 #include <net/addrconf.h>
 #include <net/lwtunnel.h>
+#include <net/fib_notifier.h>
 
 #include <net/ip6_fib.h>
 #include <net/ip6_route.h>
@@ -302,6 +303,17 @@ static void __net_init fib6_tables_init(struct net *net)
 
 #endif
 
+static int call_fib6_entry_notifiers(struct net *net,
+				     enum fib_event_type event_type,
+				     struct rt6_info *rt)
+{
+	struct fib6_entry_notifier_info info = {
+		.rt = rt,
+	};
+
+	return call_fib6_notifiers(net, event_type, &info.info);
+}
+
 static int fib6_dump_node(struct fib6_walker *w)
 {
 	int res;
@@ -879,6 +891,8 @@ add:
 		*ins = rt;
 		rt->rt6i_node = fn;
 		atomic_inc(&rt->rt6i_ref);
+		call_fib6_entry_notifiers(info->nl_net, FIB_EVENT_ENTRY_ADD,
+					  rt);
 		if (!info->skip_notify)
 			inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags);
 		info->nl_net->ipv6.rt6_stats->fib_rt_entries++;
@@ -906,6 +920,8 @@ add:
 		rt->rt6i_node = fn;
 		rt->dst.rt6_next = iter->dst.rt6_next;
 		atomic_inc(&rt->rt6i_ref);
+		call_fib6_entry_notifiers(info->nl_net, FIB_EVENT_ENTRY_REPLACE,
+					  rt);
 		if (!info->skip_notify)
 			inet6_rt_notify(RTM_NEWROUTE, rt, info, NLM_F_REPLACE);
 		if (!(fn->fn_flags & RTN_RTINFO)) {
@@ -1459,6 +1475,7 @@ static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
 
 	fib6_purge_rt(rt, fn, net);
 
+	call_fib6_entry_notifiers(net, FIB_EVENT_ENTRY_DEL, rt);
 	if (!info->skip_notify)
 		inet6_rt_notify(RTM_DELROUTE, rt, info, 0);
 	rt6_release(rt);