net: core: Make the FIB notification chain generic

The FIB notification chain is currently soley used by IPv4 code.
However, we're going to introduce IPv6 FIB offload support, which
requires these notification as well.

As explained in commit c3852ef7f2f8 ("ipv4: fib: Replay events when
registering FIB notifier"), upon registration to the chain, the callee
receives a full dump of the FIB tables and rules by traversing all the
net namespaces. The integrity of the dump is ensured by a per-namespace
sequence counter that is incremented whenever a change to the tables or
rules occurs.

In order to allow more address families to use the chain, each family is
expected to register its fib_notifier_ops in its pernet init. These
operations allow the common code to read the family's sequence counter
as well as dump its tables and rules in the given net namespace.

Additionally, a 'family' parameter is added to sent notifications, so
that listeners could distinguish between the different families.

Implement the common code that allows listeners to register to the chain
and for address families to register their fib_notifier_ops. Subsequent
patches will implement these operations in IPv6.

In the future, ipmr and ip6mr will be extended to provide these
notifications as well.

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>

4 files changed, 54 insertions, 22 deletions

diff --git a/include/net/fib_notifier.h b/include/net/fib_notifier.h
new file mode 100644
index 000000000000..241475224f74
--- /dev/null
+++ b/include/net/fib_notifier.h
@@ -0,0 +1,44 @@
+#ifndef __NET_FIB_NOTIFIER_H
+#define __NET_FIB_NOTIFIER_H
+
+#include <linux/types.h>
+#include <linux/notifier.h>
+#include <net/net_namespace.h>
+
+struct fib_notifier_info {
+	struct net *net;
+	int family;
+};
+
+enum fib_event_type {
+	FIB_EVENT_ENTRY_REPLACE,
+	FIB_EVENT_ENTRY_APPEND,
+	FIB_EVENT_ENTRY_ADD,
+	FIB_EVENT_ENTRY_DEL,
+	FIB_EVENT_RULE_ADD,
+	FIB_EVENT_RULE_DEL,
+	FIB_EVENT_NH_ADD,
+	FIB_EVENT_NH_DEL,
+};
+
+struct fib_notifier_ops {
+	int family;
+	struct list_head list;
+	unsigned int (*fib_seq_read)(struct net *net);
+	int (*fib_dump)(struct net *net, struct notifier_block *nb);
+	struct rcu_head rcu;
+};
+
+int call_fib_notifier(struct notifier_block *nb, struct net *net,
+		      enum fib_event_type event_type,
+		      struct fib_notifier_info *info);
+int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
+		       struct fib_notifier_info *info);
+int register_fib_notifier(struct notifier_block *nb,
+			  void (*cb)(struct notifier_block *nb));
+int unregister_fib_notifier(struct notifier_block *nb);
+struct fib_notifier_ops *
+fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net);
+void fib_notifier_ops_unregister(struct fib_notifier_ops *ops);
+
+#endif
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index ef8992d49bc3..c0295c3ec5f3 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -19,6 +19,7 @@
 #include <net/flow.h>
 #include <linux/seq_file.h>
 #include <linux/rcupdate.h>
+#include <net/fib_notifier.h>
 #include <net/fib_rules.h>
 #include <net/inetpeer.h>
 #include <linux/percpu.h>
@@ -188,10 +189,6 @@ __be32 fib_info_update_nh_saddr(struct net *net, struct fib_nh *nh);
 #define FIB_RES_PREFSRC(net, res)	((res).fi->fib_prefsrc ? : \
 					 FIB_RES_SADDR(net, res))
 
-struct fib_notifier_info {
-	struct net *net;
-};
-
 struct fib_entry_notifier_info {
 	struct fib_notifier_info info; /* must be first */
 	u32 dst;
@@ -212,25 +209,14 @@ struct fib_nh_notifier_info {
 	struct fib_nh *fib_nh;
 };
 
-enum fib_event_type {
-	FIB_EVENT_ENTRY_REPLACE,
-	FIB_EVENT_ENTRY_APPEND,
-	FIB_EVENT_ENTRY_ADD,
-	FIB_EVENT_ENTRY_DEL,
-	FIB_EVENT_RULE_ADD,
-	FIB_EVENT_RULE_DEL,
-	FIB_EVENT_NH_ADD,
-	FIB_EVENT_NH_DEL,
-};
-
-int register_fib_notifier(struct notifier_block *nb,
-			  void (*cb)(struct notifier_block *nb));
-int unregister_fib_notifier(struct notifier_block *nb);
-int call_fib_notifier(struct notifier_block *nb, struct net *net,
-		      enum fib_event_type event_type,
-		      struct fib_notifier_info *info);
-int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
+int call_fib4_notifier(struct notifier_block *nb, struct net *net,
+		       enum fib_event_type event_type,
 		       struct fib_notifier_info *info);
+int call_fib4_notifiers(struct net *net, enum fib_event_type event_type,
+			struct fib_notifier_info *info);
+
+int __net_init fib4_notifier_init(struct net *net);
+void __net_exit fib4_notifier_exit(struct net *net);
 
 void fib_notify(struct net *net, struct notifier_block *nb);
 #ifdef CONFIG_IP_MULTIPLE_TABLES
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 1c401bd4c2e0..57faa375eab9 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -88,6 +88,7 @@ struct net {
 	/* core fib_rules */
 	struct list_head	rules_ops;
 
+	struct list_head	fib_notifier_ops;  /* protected by net_mutex */
 
 	struct net_device       *loopback_dev;          /* The loopback */
 	struct netns_core	core;
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index 9a14a0850b0e..20d061c805e3 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -159,6 +159,7 @@ struct netns_ipv4 {
 	int sysctl_fib_multipath_hash_policy;
 #endif
 
+	struct fib_notifier_ops	*notifier_ops;
 	unsigned int	fib_seq;	/* protected by rtnl_mutex */
 
 	atomic_t	rt_genid;