xfrm: add support for UDPv6 encapsulation of ESP

This patch adds support for encapsulation of ESP over UDPv6. The code
is very similar to the IPv4 encapsulation implementation, and allows
to easily add espintcp on IPv6 as a follow-up.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/net/ipv6/xfrm6_protocol.c b/net/ipv6/xfrm6_protocol.c
index 34cb65c7d5a7..ea2f805d3b01 100644
--- a/net/ipv6/xfrm6_protocol.c
+++ b/net/ipv6/xfrm6_protocol.c
@@ -14,6 +14,7 @@
 #include <linux/mutex.h>
 #include <linux/skbuff.h>
 #include <linux/icmpv6.h>
+#include <net/ip6_route.h>
 #include <net/ipv6.h>
 #include <net/protocol.h>
 #include <net/xfrm.h>
@@ -58,6 +59,53 @@ static int xfrm6_rcv_cb(struct sk_buff *skb, u8 protocol, int err)
 	return 0;
 }
 
+int xfrm6_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
+		    int encap_type)
+{
+	int ret;
+	struct xfrm6_protocol *handler;
+	struct xfrm6_protocol __rcu **head = proto_handlers(nexthdr);
+
+	XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip6 = NULL;
+	XFRM_SPI_SKB_CB(skb)->family = AF_INET6;
+	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct ipv6hdr, daddr);
+
+	if (!head)
+		goto out;
+
+	if (!skb_dst(skb)) {
+		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+		int flags = RT6_LOOKUP_F_HAS_SADDR;
+		struct dst_entry *dst;
+		struct flowi6 fl6 = {
+			.flowi6_iif   = skb->dev->ifindex,
+			.daddr        = ip6h->daddr,
+			.saddr        = ip6h->saddr,
+			.flowlabel    = ip6_flowinfo(ip6h),
+			.flowi6_mark  = skb->mark,
+			.flowi6_proto = ip6h->nexthdr,
+		};
+
+		dst = ip6_route_input_lookup(dev_net(skb->dev), skb->dev, &fl6,
+					     skb, flags);
+		if (dst->error)
+			goto drop;
+		skb_dst_set(skb, dst);
+	}
+
+	for_each_protocol_rcu(*head, handler)
+		if ((ret = handler->input_handler(skb, nexthdr, spi, encap_type)) != -EINVAL)
+			return ret;
+
+out:
+	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
+
+drop:
+	kfree_skb(skb);
+	return 0;
+}
+EXPORT_SYMBOL(xfrm6_rcv_encap);
+
 static int xfrm6_esp_rcv(struct sk_buff *skb)
 {
 	int ret;