net: ipv6: send unsolicited NA after DAD

Unsolicited IPv6 neighbor advertisements should be sent after DAD
completes. Update ndisc_send_unsol_na to skip tentative, non-optimistic
addresses and have those sent by addrconf_dad_completed after DAD.

Fixes: 4a6e3c5def13c ("net: ipv6: send unsolicited NA on admin up")
Reported-by: Vivek Venkatraman <vivek@cumulusnetworks.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -186,7 +186,8 @@ static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
 
 static void addrconf_dad_start(struct inet6_ifaddr *ifp);
 static void addrconf_dad_work(struct work_struct *w);
-static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id);
+static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id,
+				   bool send_na);
 static void addrconf_dad_run(struct inet6_dev *idev);
 static void addrconf_rs_timer(struct timer_list *t);
 static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifa);
@@ -3838,12 +3839,17 @@ static void addrconf_dad_begin(struct inet6_ifaddr *ifp)
 	     idev->cnf.accept_dad < 1) ||
 	    !(ifp->flags&IFA_F_TENTATIVE) ||
 	    ifp->flags & IFA_F_NODAD) {
+		bool send_na = false;
+
+		if (ifp->flags & IFA_F_TENTATIVE &&
+		    !(ifp->flags & IFA_F_OPTIMISTIC))
+			send_na = true;
 		bump_id = ifp->flags & IFA_F_TENTATIVE;
 		ifp->flags &= ~(IFA_F_TENTATIVE|IFA_F_OPTIMISTIC|IFA_F_DADFAILED);
 		spin_unlock(&ifp->lock);
 		read_unlock_bh(&idev->lock);
 
-		addrconf_dad_completed(ifp, bump_id);
+		addrconf_dad_completed(ifp, bump_id, send_na);
 		return;
 	}
 
@@ -3972,16 +3978,21 @@ static void addrconf_dad_work(struct work_struct *w)
 	}
 
 	if (ifp->dad_probes == 0) {
+		bool send_na = false;
+
 		/*
 		 * DAD was successful
 		 */
 
+		if (ifp->flags & IFA_F_TENTATIVE &&
+		    !(ifp->flags & IFA_F_OPTIMISTIC))
+			send_na = true;
 		bump_id = ifp->flags & IFA_F_TENTATIVE;
 		ifp->flags &= ~(IFA_F_TENTATIVE|IFA_F_OPTIMISTIC|IFA_F_DADFAILED);
 		spin_unlock(&ifp->lock);
 		write_unlock_bh(&idev->lock);
 
-		addrconf_dad_completed(ifp, bump_id);
+		addrconf_dad_completed(ifp, bump_id, send_na);
 
 		goto out;
 	}
@@ -4019,7 +4030,8 @@ static bool ipv6_lonely_lladdr(struct inet6_ifaddr *ifp)
 	return true;
 }
 
-static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id)
+static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id,
+				   bool send_na)
 {
 	struct net_device *dev = ifp->idev->dev;
 	struct in6_addr lladdr;
@@ -4051,6 +4063,16 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp, bool bump_id)
 	if (send_mld)
 		ipv6_mc_dad_complete(ifp->idev);
 
+	/* send unsolicited NA if enabled */
+	if (send_na &&
+	    (ifp->idev->cnf.ndisc_notify ||
+	     dev_net(dev)->ipv6.devconf_all->ndisc_notify)) {
+		ndisc_send_na(dev, &in6addr_linklocal_allnodes, &ifp->addr,
+			      /*router=*/ !!ifp->idev->cnf.forwarding,
+			      /*solicited=*/ false, /*override=*/ true,
+			      /*inc_opt=*/ true);
+	}
+
 	if (send_rs) {
 		/*
 		 *	If a host as already performed a random delay

net/ipv6/ndisc.c

@@ -566,6 +566,11 @@ static void ndisc_send_unsol_na(struct net_device *dev)
 
 	read_lock_bh(&idev->lock);
 	list_for_each_entry(ifa, &idev->addr_list, if_list) {
+		/* skip tentative addresses until dad completes */
+		if (ifa->flags & IFA_F_TENTATIVE &&
+		    !(ifa->flags & IFA_F_OPTIMISTIC))
+			continue;
+
 		ndisc_send_na(dev, &in6addr_linklocal_allnodes, &ifa->addr,
 			      /*router=*/ !!idev->cnf.forwarding,
 			      /*solicited=*/ false, /*override=*/ true,