1 files changed, 42 insertions, 37 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d6ff12617f36..cd3fb301da38 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1499,6 +1499,33 @@ static bool ipv6_chk_same_addr(struct net *net, const struct in6_addr *addr,
         return false;
 }
 
+/* Compares an address/prefix_len with addresses on device @dev.
+ * If one is found it returns true.
+ */
+bool ipv6_chk_custom_prefix(const struct in6_addr *addr,
+        const unsigned int prefix_len, struct net_device *dev)
+{
+        struct inet6_dev *idev;
+        struct inet6_ifaddr *ifa;
+        bool ret = false;
+
+        rcu_read_lock();
+        idev = __in6_dev_get(dev);
+        if (idev) {
+                read_lock_bh(&idev->lock);
+                list_for_each_entry(ifa, &idev->addr_list, if_list) {
+                        ret = ipv6_prefix_equal(addr, &ifa->addr, prefix_len);
+                        if (ret)
+                                break;
+                }
+                read_unlock_bh(&idev->lock);
+        }
+        rcu_read_unlock();
+
+        return ret;
+}
+EXPORT_SYMBOL(ipv6_chk_custom_prefix);
+
 int ipv6_chk_prefix(const struct in6_addr *addr, struct net_device *dev)
 {
         struct inet6_dev *idev;
@@ -2193,43 +2220,21 @@ ok:
                         else
                                 stored_lft = 0;
                         if (!update_lft && !create && stored_lft) {
-                                if (valid_lft > MIN_VALID_LIFETIME ||
-                                    valid_lft > stored_lft)
-                                        update_lft = 1;
-                                else if (stored_lft <= MIN_VALID_LIFETIME) {
-                                        /* valid_lft <= stored_lft is always true */
-                                        /*
-                                         * RFC 4862 Section 5.5.3e:
-                                         * "Note that the preferred lifetime of
-                                         *  the corresponding address is always
-                                         *  reset to the Preferred Lifetime in
-                                         *  the received Prefix Information
-                                         *  option, regardless of whether the
-                                         *  valid lifetime is also reset or
-                                         *  ignored."
-                                         *
-                                         *  So if the preferred lifetime in
-                                         *  this advertisement is different
-                                         *  than what we have stored, but the
-                                         *  valid lifetime is invalid, just
-                                         *  reset prefered_lft.
-                                         *
-                                         *  We must set the valid lifetime
-                                         *  to the stored lifetime since we'll
-                                         *  be updating the timestamp below,
-                                         *  else we'll set it back to the
-                                         *  minimum.
-                                         */
-                                        if (prefered_lft != ifp->prefered_lft) {
-                                                valid_lft = stored_lft;
-                                                update_lft = 1;
-                                        }
-                                } else {
-                                        valid_lft = MIN_VALID_LIFETIME;
-                                        if (valid_lft < prefered_lft)
-                                                prefered_lft = valid_lft;
-                                        update_lft = 1;
-                                }
+                                const u32 minimum_lft = min(
+                                        stored_lft, (u32)MIN_VALID_LIFETIME);
+                                valid_lft = max(valid_lft, minimum_lft);
+
+                                /* RFC4862 Section 5.5.3e:
+                                 * "Note that the preferred lifetime of the
+                                 *  corresponding address is always reset to
+                                 *  the Preferred Lifetime in the received
+                                 *  Prefix Information option, regardless of
+                                 *  whether the valid lifetime is also reset or
+                                 *  ignored."
+                                 *
+                                 * So we should always update prefered_lft here.
+                                 */
+                                update_lft = 1;
                         }
 
                         if (update_lft) {