[PATCH net 06/11] ovpn: replace bind when clearing stale local source

@@ -185,7 +185,7 @@ static void ovpn_dst_cache_check_key(struct ovpn_peer *peer,
  * to detect whether the bind was replaced while the route lookup was running.
  *
  * Return: true if the lookup result still matches the current peer state and
- * may update the dst cache.
+ * may update the dst cache or replace the bind.
  */
 static bool ovpn_dst_cache_current(const struct ovpn_peer *peer,
 				   const struct ovpn_bind *bind,

@@ -218,6 +218,9 @@ static int ovpn_udp4_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 			    struct sk_buff *skb,
 			    const struct ovpn_route_key *key)
 {
+	struct sockaddr_storage remote;
+	struct in_addr local = {};
+	bool reset_local = false;
 	struct rtable *rt;
 	struct flowi4 fl = {
 		.saddr = bind->local.ipv4.s_addr,

@@ -236,24 +239,17 @@ static int ovpn_udp4_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 
 	if (fl.saddr && unlikely(!inet_confirm_addr(sock_net(sk), NULL, 0,
 						    fl.saddr, RT_SCOPE_HOST))) {
-		/* we may end up here when the cached address is not usable
-		 * anymore. In this case we reset address/cache and perform a
-		 * new look up
+		/* The learned local address is not usable anymore.
+		 * Retry with source address autoselection.
 		 */
 		fl.saddr = 0;
-		spin_lock_bh(&peer->lock);
-		bind->local.ipv4.s_addr = 0;
-		spin_unlock_bh(&peer->lock);
-		dst_cache_reset(cache);
+		reset_local = true;
 	}
 
 	rt = ip_route_output_flow(sock_net(sk), &fl, sk);
 	if (IS_ERR(rt) && PTR_ERR(rt) == -EINVAL) {
 		fl.saddr = 0;
-		spin_lock_bh(&peer->lock);
-		bind->local.ipv4.s_addr = 0;
-		spin_unlock_bh(&peer->lock);
-		dst_cache_reset(cache);
+		reset_local = true;
 
 		rt = ip_route_output_flow(sock_net(sk), &fl, sk);
 	}

@@ -267,10 +263,28 @@ static int ovpn_udp4_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 		goto err;
 	}
 
-	/* avoid storing a stale cache */
+	/* avoid storing a stale cache or local address */
 	spin_lock_bh(&peer->lock);
-	if (likely(ovpn_dst_cache_current(peer, bind, key)))
-		dst_cache_set_ip4(cache, &rt->dst, fl.saddr);
+	if (likely(ovpn_dst_cache_current(peer, bind, key))) {
+		if (!reset_local) {
+			dst_cache_set_ip4(cache, &rt->dst, fl.saddr);
+			spin_unlock_bh(&peer->lock);
+			goto transmit;
+		}
+
+		/* invalidate per-CPU dst entries that may still carry
+		 * the stale source
+		 */
+		dst_cache_reset(cache);
+
+		/* preserve the current remote */
+		memcpy(&remote, &bind->remote, sizeof(struct sockaddr_in));
+		/* The current packet already has a valid wildcard-source route.
+		 * If replacing the bind fails, leave the stale local in place;
+		 * a later cache miss will retry the repair.
+		 */
+		ovpn_peer_reset_sockaddr(peer, &remote, &local);
+	}
 	spin_unlock_bh(&peer->lock);
 
 transmit:

@@ -300,6 +314,9 @@ static int ovpn_udp6_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 			    struct sk_buff *skb,
 			    const struct ovpn_route_key *key)
 {
+	struct in6_addr local = in6addr_any;
+	struct sockaddr_storage remote;
+	bool reset_local = false;
 	struct dst_entry *dst;
 	int ret;
 

@@ -320,15 +337,11 @@ static int ovpn_udp6_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 
 	if (!ipv6_addr_any(&fl.saddr) &&
 	    unlikely(!ipv6_chk_addr(sock_net(sk), &fl.saddr, NULL, 0))) {
-		/* we may end up here when the cached address is not usable
-		 * anymore. In this case we reset address/cache and perform a
-		 * new look up
+		/* The learned local address is not usable anymore.
+		 * Retry with source address autoselection.
 		 */
 		fl.saddr = in6addr_any;
-		spin_lock_bh(&peer->lock);
-		bind->local.ipv6 = in6addr_any;
-		spin_unlock_bh(&peer->lock);
-		dst_cache_reset(cache);
+		reset_local = true;
 	}
 
 	dst = ip6_dst_lookup_flow(sock_net(sk), sk, &fl, NULL);

@@ -340,10 +353,28 @@ static int ovpn_udp6_output(struct ovpn_peer *peer, struct ovpn_bind *bind,
 		goto err;
 	}
 
-	/* avoid storing a stale cache */
+	/* avoid storing a stale cache or local address */
 	spin_lock_bh(&peer->lock);
-	if (likely(ovpn_dst_cache_current(peer, bind, key)))
-		dst_cache_set_ip6(cache, dst, &fl.saddr);
+	if (likely(ovpn_dst_cache_current(peer, bind, key))) {
+		if (!reset_local) {
+			dst_cache_set_ip6(cache, dst, &fl.saddr);
+			spin_unlock_bh(&peer->lock);
+			goto transmit;
+		}
+
+		/* invalidate per-CPU dst entries that may still carry
+		 * the stale source
+		 */
+		dst_cache_reset(cache);
+
+		/* preserve the current remote */
+		memcpy(&remote, &bind->remote, sizeof(struct sockaddr_in6));
+		/* The current packet already has a valid wildcard-source route.
+		 * If replacing the bind fails, leave the stale local in place;
+		 * a later cache miss will retry the repair.
+		 */
+		ovpn_peer_reset_sockaddr(peer, &remote, &local);
+	}
 	spin_unlock_bh(&peer->lock);
 
 transmit: