fou: Add encap ops for IPv6 tunnels

This patch add a new fou6 module that provides encapsulation
operations for IPv6.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: tomratbert

include/net/fou.h

@@ -9,7 +9,7 @@
 #include <net/udp.h>
 
 size_t fou_encap_hlen(struct ip_tunnel_encap *e);
-static size_t gue_encap_hlen(struct ip_tunnel_encap *e);
+size_t gue_encap_hlen(struct ip_tunnel_encap *e);
 
 int __fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
 		       u8 *protocol, __be16 *sport, int type);

net/ipv6/Makefile

@@ -42,6 +42,7 @@ obj-$(CONFIG_IPV6_VTI) += ip6_vti.o
 obj-$(CONFIG_IPV6_SIT) += sit.o
 obj-$(CONFIG_IPV6_TUNNEL) += ip6_tunnel.o
 obj-$(CONFIG_IPV6_GRE) += ip6_gre.o
+obj-$(CONFIG_NET_FOU) += fou6.o
 
 obj-y += addrconf_core.o exthdrs_core.o ip6_checksum.o ip6_icmp.o
 obj-$(CONFIG_INET) += output_core.o protocol.o $(ipv6-offload)

net/ipv6/fou6.c

@@ -0,0 +1,140 @@
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/socket.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/udp.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <net/fou.h>
+#include <net/ip.h>
+#include <net/ip6_tunnel.h>
+#include <net/ip6_checksum.h>
+#include <net/protocol.h>
+#include <net/udp.h>
+#include <net/udp_tunnel.h>
+
+static void fou6_build_udp(struct sk_buff *skb, struct ip_tunnel_encap *e,
+			   struct flowi6 *fl6, u8 *protocol, __be16 sport)
+{
+	struct udphdr *uh;
+
+	skb_push(skb, sizeof(struct udphdr));
+	skb_reset_transport_header(skb);
+
+	uh = udp_hdr(skb);
+
+	uh->dest = e->dport;
+	uh->source = sport;
+	uh->len = htons(skb->len);
+	udp6_set_csum(!(e->flags & TUNNEL_ENCAP_FLAG_CSUM6), skb,
+		      &fl6->saddr, &fl6->daddr, skb->len);
+
+	*protocol = IPPROTO_UDP;
+}
+
+int fou6_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
+		      u8 *protocol, struct flowi6 *fl6)
+{
+	__be16 sport;
+	int err;
+	int type = e->flags & TUNNEL_ENCAP_FLAG_CSUM6 ?
+		SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
+
+	err = __fou_build_header(skb, e, protocol, &sport, type);
+	if (err)
+		return err;
+
+	fou6_build_udp(skb, e, fl6, protocol, sport);
+
+	return 0;
+}
+EXPORT_SYMBOL(fou6_build_header);
+
+int gue6_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
+		      u8 *protocol, struct flowi6 *fl6)
+{
+	__be16 sport;
+	int err;
+	int type = e->flags & TUNNEL_ENCAP_FLAG_CSUM6 ?
+		SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;
+
+	err = __gue_build_header(skb, e, protocol, &sport, type);
+	if (err)
+		return err;
+
+	fou6_build_udp(skb, e, fl6, protocol, sport);
+
+	return 0;
+}
+EXPORT_SYMBOL(gue6_build_header);
+
+#ifdef CONFIG_NET_FOU_IP_TUNNELS
+
+static const struct ip6_tnl_encap_ops fou_ip6tun_ops = {
+	.encap_hlen = fou_encap_hlen,
+	.build_header = fou6_build_header,
+};
+
+static const struct ip6_tnl_encap_ops gue_ip6tun_ops = {
+	.encap_hlen = gue_encap_hlen,
+	.build_header = gue6_build_header,
+};
+
+static int ip6_tnl_encap_add_fou_ops(void)
+{
+	int ret;
+
+	ret = ip6_tnl_encap_add_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
+	if (ret < 0) {
+		pr_err("can't add fou6 ops\n");
+		return ret;
+	}
+
+	ret = ip6_tnl_encap_add_ops(&gue_ip6tun_ops, TUNNEL_ENCAP_GUE);
+	if (ret < 0) {
+		pr_err("can't add gue6 ops\n");
+		ip6_tnl_encap_del_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void ip6_tnl_encap_del_fou_ops(void)
+{
+	ip6_tnl_encap_del_ops(&fou_ip6tun_ops, TUNNEL_ENCAP_FOU);
+	ip6_tnl_encap_del_ops(&gue_ip6tun_ops, TUNNEL_ENCAP_GUE);
+}
+
+#else
+
+static int ip6_tnl_encap_add_fou_ops(void)
+{
+	return 0;
+}
+
+static void ip6_tnl_encap_del_fou_ops(void)
+{
+}
+
+#endif
+
+static int __init fou6_init(void)
+{
+	int ret;
+
+	ret = ip6_tnl_encap_add_fou_ops();
+
+	return ret;
+}
+
+static void __exit fou6_fini(void)
+{
+	ip6_tnl_encap_del_fou_ops();
+}
+
+module_init(fou6_init);
+module_exit(fou6_fini);
+MODULE_AUTHOR("Tom Herbert <therbert@google.com>");
+MODULE_LICENSE("GPL");