3 files changed, 23 insertions, 3 deletions

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index d13573bb879e..80456f72d70a 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -62,6 +62,9 @@ int addrconf_set_dstaddr(struct net *net, void __user *arg);
 
 int ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
                   const struct net_device *dev, int strict);
+int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
+                            const struct net_device *dev, int strict,
+                            u32 banned_flags);
 
 #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
 int ipv6_chk_home_addr(struct net *net, const struct in6_addr *addr);
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f7c8bbeb27b7..62900aee4c58 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1519,15 +1519,30 @@ static int ipv6_count_addresses(struct inet6_dev *idev)
 int ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
                   const struct net_device *dev, int strict)
 {
+        return ipv6_chk_addr_and_flags(net, addr, dev, strict, IFA_F_TENTATIVE);
+}
+EXPORT_SYMBOL(ipv6_chk_addr);
+
+int ipv6_chk_addr_and_flags(struct net *net, const struct in6_addr *addr,
+                            const struct net_device *dev, int strict,
+                            u32 banned_flags)
+{
         struct inet6_ifaddr *ifp;
         unsigned int hash = inet6_addr_hash(addr);
+        u32 ifp_flags;
 
         rcu_read_lock_bh();
         hlist_for_each_entry_rcu(ifp, &inet6_addr_lst[hash], addr_lst) {
                 if (!net_eq(dev_net(ifp->idev->dev), net))
                         continue;
+                /* Decouple optimistic from tentative for evaluation here.
+                 * Ban optimistic addresses explicitly, when required.
+                 */
+                ifp_flags = (ifp->flags&IFA_F_OPTIMISTIC)
+                            ? (ifp->flags&~IFA_F_TENTATIVE)
+                            : ifp->flags;
                 if (ipv6_addr_equal(&ifp->addr, addr) &&
-                    !(ifp->flags&IFA_F_TENTATIVE) &&
+                    !(ifp_flags&banned_flags) &&
                     (dev == NULL || ifp->idev->dev == dev ||
                      !(ifp->scope&(IFA_LINK|IFA_HOST) || strict))) {
                         rcu_read_unlock_bh();
@@ -1538,7 +1553,7 @@ int ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
         rcu_read_unlock_bh();
         return 0;
 }
-EXPORT_SYMBOL(ipv6_chk_addr);
+EXPORT_SYMBOL(ipv6_chk_addr_and_flags);
 
 static bool ipv6_chk_same_addr(struct net *net, const struct in6_addr *addr,
                                struct net_device *dev)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 682866777d53..113fc6cd5a0c 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -655,7 +655,9 @@ static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb)
         struct in6_addr *target = (struct in6_addr *)&neigh->primary_key;
         int probes = atomic_read(&neigh->probes);
 
-        if (skb && ipv6_chk_addr(dev_net(dev), &ipv6_hdr(skb)->saddr, dev, 1))
+        if (skb && ipv6_chk_addr_and_flags(dev_net(dev), &ipv6_hdr(skb)->saddr,
+                                           dev, 1,
+                                           IFA_F_TENTATIVE|IFA_F_OPTIMISTIC))
                 saddr = &ipv6_hdr(skb)->saddr;
         probes -= NEIGH_VAR(neigh->parms, UCAST_PROBES);
         if (probes < 0) {