1 files changed, 78 insertions, 11 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index c55698d19d68..1216c920f945 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -462,6 +462,61 @@ csum_copy_err:
 	goto try_again;
 }
 
+DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
+void udpv6_encap_enable(void)
+{
+	static_branch_enable(&udpv6_encap_needed_key);
+}
+EXPORT_SYMBOL(udpv6_encap_enable);
+
+/* Try to match ICMP errors to UDP tunnels by looking up a socket without
+ * reversing source and destination port: this will match tunnels that force the
+ * same destination port on both endpoints (e.g. VXLAN, GENEVE). Note that
+ * lwtunnels might actually break this assumption by being configured with
+ * different destination ports on endpoints, in this case we won't be able to
+ * trace ICMP messages back to them.
+ *
+ * Then ask the tunnel implementation to match the error against a valid
+ * association.
+ *
+ * Return the socket if we have a match.
+ */
+static struct sock *__udp6_lib_err_encap(struct net *net,
+					 const struct ipv6hdr *hdr, int offset,
+					 struct udphdr *uh,
+					 struct udp_table *udptable,
+					 struct sk_buff *skb)
+{
+	int (*lookup)(struct sock *sk, struct sk_buff *skb);
+	int network_offset, transport_offset;
+	struct udp_sock *up;
+	struct sock *sk;
+
+	sk = __udp6_lib_lookup(net, &hdr->daddr, uh->source,
+			       &hdr->saddr, uh->dest,
+			       inet6_iif(skb), 0, udptable, skb);
+	if (!sk)
+		return NULL;
+
+	network_offset = skb_network_offset(skb);
+	transport_offset = skb_transport_offset(skb);
+
+	/* Network header needs to point to the outer IPv6 header inside ICMP */
+	skb_reset_network_header(skb);
+
+	/* Transport header needs to point to the UDP header */
+	skb_set_transport_header(skb, offset);
+
+	up = udp_sk(sk);
+	lookup = READ_ONCE(up->encap_err_lookup);
+	if (!lookup || lookup(sk, skb))
+		sk = NULL;
+
+	skb_set_transport_header(skb, transport_offset);
+	skb_set_network_header(skb, network_offset);
+	return sk;
+}
+
 void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 		    u8 type, u8 code, int offset, __be32 info,
 		    struct udp_table *udptable)
@@ -471,6 +526,7 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	const struct in6_addr *saddr = &hdr->saddr;
 	const struct in6_addr *daddr = &hdr->daddr;
 	struct udphdr *uh = (struct udphdr *)(skb->data+offset);
+	bool tunnel = false;
 	struct sock *sk;
 	int harderr;
 	int err;
@@ -479,9 +535,18 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	sk = __udp6_lib_lookup(net, daddr, uh->dest, saddr, uh->source,
 			       inet6_iif(skb), inet6_sdif(skb), udptable, skb);
 	if (!sk) {
-		__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),
-				  ICMP6_MIB_INERRORS);
-		return;
+		/* No socket for error: try tunnels before discarding */
+		if (static_branch_unlikely(&udpv6_encap_needed_key)) {
+			sk = __udp6_lib_err_encap(net, hdr, offset, uh,
+						  udptable, skb);
+		}
+
+		if (!sk) {
+			__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),
+					  ICMP6_MIB_INERRORS);
+			return;
+		}
+		tunnel = true;
 	}
 
 	harderr = icmpv6_err_convert(type, code, &err);
@@ -495,10 +560,19 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 			harderr = 1;
 	}
 	if (type == NDISC_REDIRECT) {
-		ip6_sk_redirect(skb, sk);
+		if (tunnel) {
+			ip6_redirect(skb, sock_net(sk), inet6_iif(skb),
+				     sk->sk_mark, sk->sk_uid);
+		} else {
+			ip6_sk_redirect(skb, sk);
+		}
 		goto out;
 	}
 
+	/* Tunnels don't have an application socket: don't pass errors back */
+	if (tunnel)
+		goto out;
+
 	if (!np->recverr) {
 		if (!harderr || sk->sk_state != TCP_ESTABLISHED)
 			goto out;
@@ -547,13 +621,6 @@ static __inline__ void udpv6_err(struct sk_buff *skb,
 	__udp6_lib_err(skb, opt, type, code, offset, info, &udp_table);
 }
 
-DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
-void udpv6_encap_enable(void)
-{
-	static_branch_enable(&udpv6_encap_needed_key);
-}
-EXPORT_SYMBOL(udpv6_encap_enable);
-
 static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 {
 	struct udp_sock *up = udp_sk(sk);