ipv4: fib_rules: Add notifier info to FIB rules notifications

Whenever a FIB rule is added or removed, a notification is sent in the
FIB notification chain. However, listeners don't have a way to tell
which rule was added or removed.

This is problematic as we would like to give listeners the ability to
decide which action to execute based on the notified rule. Specifically,
offloading drivers should be able to determine if they support the
reflection of the notified FIB rule and flush their LPM tables in case
they don't.

Do that by adding a notifier info to these notifications and embed the
common FIB rule struct in it.

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

include/net/ip_fib.h

@@ -213,6 +213,11 @@ struct fib_entry_notifier_info {
 	u32 tb_id;
 };
 
+struct fib_rule_notifier_info {
+	struct fib_notifier_info info; /* must be first */
+	struct fib_rule *rule;
+};
+
 struct fib_nh_notifier_info {
 	struct fib_notifier_info info; /* must be first */
 	struct fib_nh *fib_nh;

net/ipv4/fib_rules.c

@@ -186,11 +186,14 @@ static struct fib_table *fib_empty_table(struct net *net)
 }
 
 static int call_fib_rule_notifiers(struct net *net,
-				   enum fib_event_type event_type)
+				   enum fib_event_type event_type,
+				   struct fib_rule *rule)
 {
-	struct fib_notifier_info info;
+	struct fib_rule_notifier_info info = {
+		.rule = rule,
+	};
 
-	return call_fib_notifiers(net, event_type, &info);
+	return call_fib_notifiers(net, event_type, &info.info);
 }
 
 void fib_rules_notify(struct net *net, struct notifier_block *nb)
@@ -257,7 +260,7 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 	rule4->tos = frh->tos;
 
 	net->ipv4.fib_has_custom_rules = true;
-	call_fib_rule_notifiers(net, FIB_EVENT_RULE_ADD);
+	call_fib_rule_notifiers(net, FIB_EVENT_RULE_ADD, rule);
 
 	err = 0;
 errout:
@@ -279,7 +282,7 @@ static int fib4_rule_delete(struct fib_rule *rule)
 		net->ipv4.fib_num_tclassid_users--;
 #endif
 	net->ipv4.fib_has_custom_rules = true;
-	call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL);
+	call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL, rule);
 errout:
 	return err;
 }