net: use dst_confirm_neigh for UDP, RAW, ICMP, L2TP

BugLink: https://bugs.launchpad.net/bugs/1715812

When same struct dst_entry can be used for many different
neighbours we can not use it for pending confirmations.

The datagram protocols can use MSG_CONFIRM to confirm the
neighbour. When used with MSG_PROBE we do not reach the
code where neighbour is confirmed, so we have to do the
same slow lookup by using the dst_confirm_neigh() helper.
When MSG_PROBE is not used, ip_append_data/ip6_append_data
will set the skb flag dst_pending_confirm.
Reported-by: YueHaibing <yuehaibing@huawei.com>
Fixes: 5110effe ("net: Do delayed neigh confirmation.")
Fixes: f2bb4bed ("ipv4: Cache output routes in fib_info nexthops.")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(backported from commit 0dec879f)
Signed-off-by: Daniel Axtens <daniel.axtens@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

net/ipv4/ip_output.c

@@ -853,6 +853,9 @@ static inline int ip_ufo_append_data(struct sock *sk,
 
 		skb->csum = 0;
 
+		if (flags & MSG_CONFIRM)
+			skb_set_dst_pending_confirm(skb, 1);
+
 		__skb_queue_tail(queue, skb);
 	} else if (skb_is_gso(skb)) {
 		goto append;
@@ -1055,6 +1058,9 @@ static int __ip_append_data(struct sock *sk,
 			exthdrlen = 0;
 			csummode = CHECKSUM_NONE;
 
+			if ((flags & MSG_CONFIRM) && !skb_prev)
+				skb_set_dst_pending_confirm(skb, 1);
+
 			/*
 			 * Put the packet on the pending queue.
 			 */

net/ipv4/ping.c

@@ -852,7 +852,8 @@ static int ping_v4_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	return err;
 
 do_confirm:
-	dst_confirm(&rt->dst);
+	if (msg->msg_flags & MSG_PROBE)
+		dst_confirm_neigh(&rt->dst, &fl4.daddr);
 	if (!(msg->msg_flags & MSG_PROBE) || len)
 		goto back_from_confirm;
 	err = 0;

net/ipv4/raw.c

@@ -382,6 +382,9 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
 
 	sock_tx_timestamp(sk, &skb_shinfo(skb)->tx_flags);
 
+	if (flags & MSG_CONFIRM)
+		skb_set_dst_pending_confirm(skb, 1);
+
 	skb->transport_header = skb->network_header;
 	err = -EFAULT;
 	if (memcpy_from_msg(iph, msg, length))
@@ -670,7 +673,8 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	return len;
 
 do_confirm:
-	dst_confirm(&rt->dst);
+	if (msg->msg_flags & MSG_PROBE)
+		dst_confirm_neigh(&rt->dst, &fl4.daddr);
 	if (!(msg->msg_flags & MSG_PROBE) || len)
 		goto back_from_confirm;
 	err = 0;

net/ipv4/udp.c

@@ -1123,7 +1123,8 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	return err;
 
 do_confirm:
-	dst_confirm(&rt->dst);
+	if (msg->msg_flags & MSG_PROBE)
+		dst_confirm_neigh(&rt->dst, &fl4->daddr);
 	if (!(msg->msg_flags&MSG_PROBE) || len)
 		goto back_from_confirm;
 	err = 0;

net/ipv6/ip6_output.c

@@ -1130,6 +1130,9 @@ static inline int ip6_ufo_append_data(struct sock *sk,
 		skb->protocol = htons(ETH_P_IPV6);
 		skb->csum = 0;
 
+		if (flags & MSG_CONFIRM)
+			skb_set_dst_pending_confirm(skb, 1);
+
 		__skb_queue_tail(queue, skb);
 	} else if (skb_is_gso(skb)) {
 		goto append;
@@ -1503,6 +1506,9 @@ static int __ip6_append_data(struct sock *sk,
 			exthdrlen = 0;
 			dst_exthdrlen = 0;
 
+			if ((flags & MSG_CONFIRM) && !skb_prev)
+				skb_set_dst_pending_confirm(skb, 1);
+
 			/*
 			 * Put the packet on the pending queue
 			 */

net/ipv6/raw.c

@@ -654,6 +654,9 @@ static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length,
 
 	skb->ip_summed = CHECKSUM_NONE;
 
+	if (flags & MSG_CONFIRM)
+		skb_set_dst_pending_confirm(skb, 1);
+
 	skb->transport_header = skb->network_header;
 	err = memcpy_from_msg(iph, msg, length);
 	if (err)
@@ -918,7 +921,8 @@ static int rawv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	txopt_put(opt_to_free);
 	return err < 0 ? err : len;
 do_confirm:
-	dst_confirm(dst);
+	if (msg->msg_flags & MSG_PROBE)
+		dst_confirm_neigh(dst, &fl6.daddr);
 	if (!(msg->msg_flags & MSG_PROBE) || len)
 		goto back_from_confirm;
 	err = 0;

net/ipv6/route.c

@@ -1356,22 +1356,12 @@ static bool rt6_cache_allowed_for_pmtu(const struct rt6_info *rt)
 static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
 				 const struct ipv6hdr *iph, u32 mtu)
 {
+	const struct in6_addr *daddr, *saddr;
 	struct rt6_info *rt6 = (struct rt6_info *)dst;
 
 	if (rt6->rt6i_flags & RTF_LOCAL)
 		return;
 
-	dst_confirm(dst);
-	mtu = max_t(u32, mtu, IPV6_MIN_MTU);
-	if (mtu >= dst_mtu(dst))
-		return;
-
-	if (!rt6_cache_allowed_for_pmtu(rt6)) {
-		rt6_do_update_pmtu(rt6, mtu);
-	} else {
-		const struct in6_addr *daddr, *saddr;
-		struct rt6_info *nrt6;
-
 	if (iph) {
 		daddr = &iph->daddr;
 		saddr = &iph->saddr;
@@ -1379,8 +1369,19 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
 		daddr = &sk->sk_v6_daddr;
 		saddr = &inet6_sk(sk)->saddr;
 	} else {
-			return;
+		daddr = NULL;
+		saddr = NULL;
 	}
+	dst_confirm_neigh(dst, daddr);
+	mtu = max_t(u32, mtu, IPV6_MIN_MTU);
+	if (mtu >= dst_mtu(dst))
+		return;
+
+	if (!rt6_cache_allowed_for_pmtu(rt6)) {
+		rt6_do_update_pmtu(rt6, mtu);
+	} else if (daddr) {
+		struct rt6_info *nrt6;
+
 		nrt6 = ip6_rt_cache_alloc(rt6, daddr, saddr);
 		if (nrt6) {
 			rt6_do_update_pmtu(nrt6, mtu);
@@ -2188,7 +2189,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
 	 * Look, redirects are sent only in response to data packets,
 	 * so that this nexthop apparently is reachable. --ANK
 	 */
-	dst_confirm(&rt->dst);
+	dst_confirm_neigh(&rt->dst, &ipv6_hdr(skb)->saddr);
 
 	neigh = __neigh_lookup(&nd_tbl, &msg->target, skb->dev, 1);
 	if (!neigh)

net/ipv6/udp.c

@@ -1398,7 +1398,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	return err;
 
 do_confirm:
-	dst_confirm(dst);
+	if (msg->msg_flags & MSG_PROBE)
+		dst_confirm_neigh(dst, &fl6.daddr);
 	if (!(msg->msg_flags&MSG_PROBE) || len)
 		goto back_from_confirm;
 	err = 0;

net/l2tp/l2tp_ip6.c

@@ -642,7 +642,8 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	return err < 0 ? err : len;
 
 do_confirm:
-	dst_confirm(dst);
+	if (msg->msg_flags & MSG_PROBE)
+		dst_confirm_neigh(dst, &fl6.daddr);
 	if (!(msg->msg_flags & MSG_PROBE) || len)
 		goto back_from_confirm;
 	err = 0;