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) {