ipv6: fib: Add FIB notifiers callbacks

We're about to add IPv6 FIB offload support, so implement the necessary
callbacks in IPv6 code, which will later allow us to add routes and
rules notifications.
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

@@ -16,10 +16,12 @@
 #include <linux/ipv6_route.h>
 #include <linux/rtnetlink.h>
 #include <linux/spinlock.h>
+#include <linux/notifier.h>
 #include <net/dst.h>
 #include <net/flow.h>
 #include <net/netlink.h>
 #include <net/inetpeer.h>
+#include <net/fib_notifier.h>
 
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 #define FIB6_TABLE_HASHSZ 256
@@ -292,6 +294,15 @@ int fib6_init(void);
 
 int ipv6_route_open(struct inode *inode, struct file *file);
 
+int call_fib6_notifier(struct notifier_block *nb, struct net *net,
+		       enum fib_event_type event_type,
+		       struct fib_notifier_info *info);
+int call_fib6_notifiers(struct net *net, enum fib_event_type event_type,
+			struct fib_notifier_info *info);
+
+int __net_init fib6_notifier_init(struct net *net);
+void __net_exit fib6_notifier_exit(struct net *net);
+
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 int fib6_rules_init(void);
 void fib6_rules_cleanup(void);

include/net/netns/ipv6.h

@@ -86,6 +86,7 @@ struct netns_ipv6 {
 	atomic_t		dev_addr_genid;
 	atomic_t		fib6_sernum;
 	struct seg6_pernet_data *seg6_data;
+	struct fib_notifier_ops	*notifier_ops;
 };
 
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)

net/ipv6/Makefile

@@ -9,7 +9,7 @@ ipv6-objs :=	af_inet6.o anycast.o ip6_output.o ip6_input.o addrconf.o \
 		route.o ip6_fib.o ipv6_sockglue.o ndisc.o udp.o udplite.o \
 		raw.o icmp.o mcast.o reassembly.o tcp_ipv6.o ping.o \
 		exthdrs.o datagram.o ip6_flowlabel.o inet6_connection_sock.o \
-		udp_offload.o seg6.o
+		udp_offload.o seg6.o fib6_notifier.o
 
 ipv6-offload :=	ip6_offload.o tcpv6_offload.o exthdrs_offload.o
 

net/ipv6/fib6_notifier.c

+#include <linux/notifier.h>
+#include <linux/socket.h>
+#include <linux/kernel.h>
+#include <net/net_namespace.h>
+#include <net/fib_notifier.h>
+#include <net/netns/ipv6.h>
+#include <net/ip6_fib.h>
+
+int call_fib6_notifier(struct notifier_block *nb, struct net *net,
+		       enum fib_event_type event_type,
+		       struct fib_notifier_info *info)
+{
+	info->family = AF_INET6;
+	return call_fib_notifier(nb, net, event_type, info);
+}
+
+int call_fib6_notifiers(struct net *net, enum fib_event_type event_type,
+			struct fib_notifier_info *info)
+{
+	info->family = AF_INET6;
+	return call_fib_notifiers(net, event_type, info);
+}
+
+static unsigned int fib6_seq_read(struct net *net)
+{
+	return 0;
+}
+
+static int fib6_dump(struct net *net, struct notifier_block *nb)
+{
+	return 0;
+}
+
+static const struct fib_notifier_ops fib6_notifier_ops_template = {
+	.family		= AF_INET6,
+	.fib_seq_read	= fib6_seq_read,
+	.fib_dump	= fib6_dump,
+};
+
+int __net_init fib6_notifier_init(struct net *net)
+{
+	struct fib_notifier_ops *ops;
+
+	ops = fib_notifier_ops_register(&fib6_notifier_ops_template, net);
+	if (IS_ERR(ops))
+		return PTR_ERR(ops);
+	net->ipv6.notifier_ops = ops;
+
+	return 0;
+}
+
+void __net_exit fib6_notifier_exit(struct net *net)
+{
+	fib_notifier_ops_unregister(net->ipv6.notifier_ops);
+}

net/ipv6/ip6_fib.c

@@ -1839,6 +1839,11 @@ static void fib6_gc_timer_cb(unsigned long arg)
 static int __net_init fib6_net_init(struct net *net)
 {
 	size_t size = sizeof(struct hlist_head) * FIB6_TABLE_HASHSZ;
+	int err;
+
+	err = fib6_notifier_init(net);
+	if (err)
+		return err;
 
 	spin_lock_init(&net->ipv6.fib6_gc_lock);
 	rwlock_init(&net->ipv6.fib6_walker_lock);
@@ -1891,6 +1896,7 @@ static int __net_init fib6_net_init(struct net *net)
 out_rt6_stats:
 	kfree(net->ipv6.rt6_stats);
 out_timer:
+	fib6_notifier_exit(net);
 	return -ENOMEM;
 }
 
@@ -1907,6 +1913,7 @@ static void fib6_net_exit(struct net *net)
 	kfree(net->ipv6.fib6_main_tbl);
 	kfree(net->ipv6.fib_table_hash);
 	kfree(net->ipv6.rt6_stats);
+	fib6_notifier_exit(net);
 }
 
 static struct pernet_operations fib6_net_ops = {