net/ipv6/udp: UDP encapsulation: introduce encap_rcv hook into IPv6

Now that the sematics of udpv6_queue_rcv_skb() match IPv4's
udp_queue_rcv_skb(), introduce the UDP encap_rcv() hook for IPv6.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 39 insertions, 0 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index bc533ea8fc68..c1d91a713e8e 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -525,6 +525,14 @@ static __inline__ void udpv6_err(struct sk_buff *skb,
         __udp6_lib_err(skb, opt, type, code, offset, info, &udp_table);
 }
 
+static struct static_key udpv6_encap_needed __read_mostly;
+void udpv6_encap_enable(void)
+{
+        if (!static_key_enabled(&udpv6_encap_needed))
+                static_key_slow_inc(&udpv6_encap_needed);
+}
+EXPORT_SYMBOL(udpv6_encap_enable);
+
 int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
         struct udp_sock *up = udp_sk(sk);
@@ -534,6 +542,37 @@ int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
         if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
                 goto drop;
 
+        if (static_key_false(&udpv6_encap_needed) && up->encap_type) {
+                int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
+
+                /*
+                 * This is an encapsulation socket so pass the skb to
+                 * the socket's udp_encap_rcv() hook. Otherwise, just
+                 * fall through and pass this up the UDP socket.
+                 * up->encap_rcv() returns the following value:
+                 * =0 if skb was successfully passed to the encap
+                 *    handler or was discarded by it.
+                 * >0 if skb should be passed on to UDP.
+                 * <0 if skb should be resubmitted as proto -N
+                 */
+
+                /* if we're overly short, let UDP handle it */
+                encap_rcv = ACCESS_ONCE(up->encap_rcv);
+                if (skb->len > sizeof(struct udphdr) && encap_rcv != NULL) {
+                        int ret;
+
+                        ret = encap_rcv(sk, skb);
+                        if (ret <= 0) {
+                                UDP_INC_STATS_BH(sock_net(sk),
+                                                 UDP_MIB_INDATAGRAMS,
+                                                 is_udplite);
+                                return -ret;
+                        }
+                }
+
+                /* FALLTHROUGH -- it's a UDP Packet */
+        }
+
         /*
          * UDP-Lite specific tests, ignored on UDP sockets (see net/ipv4/udp.c).
          */