[IPV4]: Fix secondary IP addresses after promotion

This patch fixes the problem with promoting aliases when:
a) a single primary and > 1 secondary addresses
b) multiple primary addresses each with at least one secondary address

Based on earlier efforts from Brian Pomerantz <[e-mail]>,
Patrick McHardy <[e-mail]> and Thomas Graf <[e-mail]>

Signed-off-by: Jamal Hadi Salim <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/route.h

···
 extern void		ip_rt_get_source(u8 *src, struct rtable *rt);
 extern int		ip_rt_dump(struct sk_buff *skb,  struct netlink_callback *cb);
 
+struct in_ifaddr;
+extern void fib_add_ifaddr(struct in_ifaddr *);
+
 static inline void ip_rt_put(struct rtable * rt)
 {
 	if (rt)

net/ipv4/devinet.c

···
 			 int destroy)
 {
 	struct in_ifaddr *promote = NULL;
-	struct in_ifaddr *ifa1 = *ifap;
+	struct in_ifaddr *ifa, *ifa1 = *ifap;
+	struct in_ifaddr *last_prim = in_dev->ifa_list;
+	struct in_ifaddr *prev_prom = NULL;
+	int do_promote = IN_DEV_PROMOTE_SECONDARIES(in_dev);
 
 	ASSERT_RTNL();
 
···
 	 **/
 
 	if (!(ifa1->ifa_flags & IFA_F_SECONDARY)) {
-		struct in_ifaddr *ifa;
 		struct in_ifaddr **ifap1 = &ifa1->ifa_next;
 
 		while ((ifa = *ifap1) != NULL) {
+			if (!(ifa->ifa_flags & IFA_F_SECONDARY) && 
+			    ifa1->ifa_scope <= ifa->ifa_scope)
+				last_prim = ifa;
+
 			if (!(ifa->ifa_flags & IFA_F_SECONDARY) ||
 			    ifa1->ifa_mask != ifa->ifa_mask ||
 			    !inet_ifa_match(ifa1->ifa_address, ifa)) {
 				ifap1 = &ifa->ifa_next;
+				prev_prom = ifa;
 				continue;
 			}
 
-			if (!IN_DEV_PROMOTE_SECONDARIES(in_dev)) {
+			if (!do_promote) {
 				*ifap1 = ifa->ifa_next;
 
 				rtmsg_ifa(RTM_DELADDR, ifa);
···
 	 */
 	rtmsg_ifa(RTM_DELADDR, ifa1);
 	notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa1);
+
+	if (promote) {
+
+		if (prev_prom) {
+			prev_prom->ifa_next = promote->ifa_next;
+			promote->ifa_next = last_prim->ifa_next;
+			last_prim->ifa_next = promote;
+		}
+
+		promote->ifa_flags &= ~IFA_F_SECONDARY;
+		rtmsg_ifa(RTM_NEWADDR, promote);
+		notifier_call_chain(&inetaddr_chain, NETDEV_UP, promote);
+		for (ifa = promote->ifa_next; ifa; ifa = ifa->ifa_next) {
+			if (ifa1->ifa_mask != ifa->ifa_mask ||
+			    !inet_ifa_match(ifa1->ifa_address, ifa))
+					continue;
+			fib_add_ifaddr(ifa);
+		}
+
+	}
 	if (destroy) {
 		inet_free_ifa(ifa1);
 
 		if (!in_dev->ifa_list)
 			inetdev_destroy(in_dev);
-	}
-
-	if (promote && IN_DEV_PROMOTE_SECONDARIES(in_dev)) {
-		/* not sure if we should send a delete notify first? */
-		promote->ifa_flags &= ~IFA_F_SECONDARY;
-		rtmsg_ifa(RTM_NEWADDR, promote);
-		notifier_call_chain(&inetaddr_chain, NETDEV_UP, promote);
 	}
 }
 

net/ipv4/fib_frontend.c

···
 		tb->tb_delete(tb, &req.rtm, &rta, &req.nlh, NULL);
 }
 
-static void fib_add_ifaddr(struct in_ifaddr *ifa)
+void fib_add_ifaddr(struct in_ifaddr *ifa)
 {
 	struct in_device *in_dev = ifa->ifa_dev;
 	struct net_device *dev = in_dev->dev;