ip6_tun: Add infrastructure for doing encapsulation

Add encap_hlen and ip_tunnel_encap structure to ip6_tnl. Add functions
for getting encap hlen, setting up encap on a tunnel, performing
encapsulation operation.

Signed-off-by: Tom Herbert <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/ip6_tunnel.h

···
 	__u32 o_seqno;	/* The last output seqno */
 	int hlen;       /* tun_hlen + encap_hlen */
 	int tun_hlen;	/* Precalculated header length */
+	int encap_hlen; /* Encap header length (FOU,GUE) */
+	struct ip_tunnel_encap encap;
 	int mlink;
-
 };
+
+struct ip6_tnl_encap_ops {
+	size_t (*encap_hlen)(struct ip_tunnel_encap *e);
+	int (*build_header)(struct sk_buff *skb, struct ip_tunnel_encap *e,
+			    u8 *protocol, struct flowi6 *fl6);
+};
+
+extern const struct ip6_tnl_encap_ops __rcu *
+		ip6tun_encaps[MAX_IPTUN_ENCAP_OPS];
+
+int ip6_tnl_encap_add_ops(const struct ip6_tnl_encap_ops *ops,
+			  unsigned int num);
+int ip6_tnl_encap_del_ops(const struct ip6_tnl_encap_ops *ops,
+			  unsigned int num);
+int ip6_tnl_encap_setup(struct ip6_tnl *t,
+			struct ip_tunnel_encap *ipencap);
+
+static inline int ip6_encap_hlen(struct ip_tunnel_encap *e)
+{
+	const struct ip6_tnl_encap_ops *ops;
+	int hlen = -EINVAL;
+
+	if (e->type == TUNNEL_ENCAP_NONE)
+		return 0;
+
+	if (e->type >= MAX_IPTUN_ENCAP_OPS)
+		return -EINVAL;
+
+	rcu_read_lock();
+	ops = rcu_dereference(ip6tun_encaps[e->type]);
+	if (likely(ops && ops->encap_hlen))
+		hlen = ops->encap_hlen(e);
+	rcu_read_unlock();
+
+	return hlen;
+}
+
+static inline int ip6_tnl_encap(struct sk_buff *skb, struct ip6_tnl *t,
+				u8 *protocol, struct flowi6 *fl6)
+{
+	const struct ip6_tnl_encap_ops *ops;
+	int ret = -EINVAL;
+
+	if (t->encap.type == TUNNEL_ENCAP_NONE)
+		return 0;
+
+	if (t->encap.type >= MAX_IPTUN_ENCAP_OPS)
+		return -EINVAL;
+
+	rcu_read_lock();
+	ops = rcu_dereference(ip6tun_encaps[t->encap.type]);
+	if (likely(ops && ops->build_header))
+		ret = ops->build_header(skb, &t->encap, protocol, fl6);
+	rcu_read_unlock();
+
+	return ret;
+}
 
 /* Tunnel encapsulation limit destination sub-option */
 

net/ipv4/ip_tunnel_core.c

···
 #include <net/icmp.h>
 #include <net/protocol.h>
 #include <net/ip_tunnels.h>
+#include <net/ip6_tunnel.h>
 #include <net/arp.h>
 #include <net/checksum.h>
 #include <net/dsfield.h>
···
 const struct ip_tunnel_encap_ops __rcu *
 		iptun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;
 EXPORT_SYMBOL(iptun_encaps);
+
+const struct ip6_tnl_encap_ops __rcu *
+		ip6tun_encaps[MAX_IPTUN_ENCAP_OPS] __read_mostly;
+EXPORT_SYMBOL(ip6tun_encaps);
 
 void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
 		   __be32 src, __be32 dst, __u8 proto,

net/ipv6/ip6_tunnel.c

···
 	struct dst_entry *dst = NULL, *ndst = NULL;
 	struct net_device *tdev;
 	int mtu;
-	unsigned int max_headroom = sizeof(struct ipv6hdr);
+	unsigned int psh_hlen = sizeof(struct ipv6hdr) + t->encap_hlen;
+	unsigned int max_headroom = psh_hlen;
 	int err = -1;
 
 	/* NBMA tunnel */
···
 				     t->parms.name);
 		goto tx_err_dst_release;
 	}
-	mtu = dst_mtu(dst) - sizeof(*ipv6h);
+	mtu = dst_mtu(dst) - psh_hlen;
 	if (encap_limit >= 0) {
 		max_headroom += 8;
 		mtu -= 8;
···
 		skb->encapsulation = 1;
 	}
 
+	/* Calculate max headroom for all the headers and adjust
+	 * needed_headroom if necessary.
+	 */
 	max_headroom = LL_RESERVED_SPACE(dst->dev) + sizeof(struct ipv6hdr)
-			+ dst->header_len;
+			+ dst->header_len + t->hlen;
 	if (max_headroom > dev->needed_headroom)
 		dev->needed_headroom = max_headroom;
+
+	err = ip6_tnl_encap(skb, t, &proto, fl6);
+	if (err)
+		return err;
 
 	skb_push(skb, sizeof(struct ipv6hdr));
 	skb_reset_network_header(skb);
···
 	struct net_device *dev = t->dev;
 	struct __ip6_tnl_parm *p = &t->parms;
 	struct flowi6 *fl6 = &t->fl.u.ip6;
+	int t_hlen;
 
 	memcpy(dev->dev_addr, &p->laddr, sizeof(struct in6_addr));
 	memcpy(dev->broadcast, &p->raddr, sizeof(struct in6_addr));
···
 	else
 		dev->flags &= ~IFF_POINTOPOINT;
 
+	t->tun_hlen = 0;
+	t->hlen = t->encap_hlen + t->tun_hlen;
+	t_hlen = t->hlen + sizeof(struct ipv6hdr);
+
 	if (p->flags & IP6_TNL_F_CAP_XMIT) {
 		int strict = (ipv6_addr_type(&p->raddr) &
 			      (IPV6_ADDR_MULTICAST|IPV6_ADDR_LINKLOCAL));
···
 
 		if (rt->dst.dev) {
 			dev->hard_header_len = rt->dst.dev->hard_header_len +
-				sizeof(struct ipv6hdr);
+				t_hlen;
 
-			dev->mtu = rt->dst.dev->mtu - sizeof(struct ipv6hdr);
+			dev->mtu = rt->dst.dev->mtu - t_hlen;
 			if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
 				dev->mtu -= 8;
 
···
 }
 EXPORT_SYMBOL(ip6_tnl_get_iflink);
 
+int ip6_tnl_encap_add_ops(const struct ip6_tnl_encap_ops *ops,
+			  unsigned int num)
+{
+	if (num >= MAX_IPTUN_ENCAP_OPS)
+		return -ERANGE;
+
+	return !cmpxchg((const struct ip6_tnl_encap_ops **)
+			&ip6tun_encaps[num],
+			NULL, ops) ? 0 : -1;
+}
+EXPORT_SYMBOL(ip6_tnl_encap_add_ops);
+
+int ip6_tnl_encap_del_ops(const struct ip6_tnl_encap_ops *ops,
+			  unsigned int num)
+{
+	int ret;
+
+	if (num >= MAX_IPTUN_ENCAP_OPS)
+		return -ERANGE;
+
+	ret = (cmpxchg((const struct ip6_tnl_encap_ops **)
+		       &ip6tun_encaps[num],
+		       ops, NULL) == ops) ? 0 : -1;
+
+	synchronize_net();
+
+	return ret;
+}
+EXPORT_SYMBOL(ip6_tnl_encap_del_ops);
+
+int ip6_tnl_encap_setup(struct ip6_tnl *t,
+			struct ip_tunnel_encap *ipencap)
+{
+	int hlen;
+
+	memset(&t->encap, 0, sizeof(t->encap));
+
+	hlen = ip6_encap_hlen(ipencap);
+	if (hlen < 0)
+		return hlen;
+
+	t->encap.type = ipencap->type;
+	t->encap.sport = ipencap->sport;
+	t->encap.dport = ipencap->dport;
+	t->encap.flags = ipencap->flags;
+
+	t->encap_hlen = hlen;
+	t->hlen = t->encap_hlen + t->tun_hlen;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ip6_tnl_encap_setup);
+
 static const struct net_device_ops ip6_tnl_netdev_ops = {
 	.ndo_init	= ip6_tnl_dev_init,
 	.ndo_uninit	= ip6_tnl_dev_uninit,
···
 
 static void ip6_tnl_dev_setup(struct net_device *dev)
 {
-	struct ip6_tnl *t;
-
 	dev->netdev_ops = &ip6_tnl_netdev_ops;
 	dev->destructor = ip6_dev_free;
 
 	dev->type = ARPHRD_TUNNEL6;
-	dev->hard_header_len = LL_MAX_HEADER + sizeof(struct ipv6hdr);
-	dev->mtu = ETH_DATA_LEN - sizeof(struct ipv6hdr);
-	t = netdev_priv(dev);
-	if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
-		dev->mtu -= 8;
 	dev->flags |= IFF_NOARP;
 	dev->addr_len = sizeof(struct in6_addr);
+	dev->features |= NETIF_F_LLTX;
 	netif_keep_dst(dev);
 	/* This perm addr will be used as interface identifier by IPv6 */
 	dev->addr_assign_type = NET_ADDR_RANDOM;
···
 {
 	struct ip6_tnl *t = netdev_priv(dev);
 	int ret;
+	int t_hlen;
 
 	t->dev = dev;
 	t->net = dev_net(dev);
···
 	if (ret)
 		goto destroy_dst;
 
-	t->hlen = 0;
 	t->tun_hlen = 0;
+	t->hlen = t->encap_hlen + t->tun_hlen;
+	t_hlen = t->hlen + sizeof(struct ipv6hdr);
+
+	dev->type = ARPHRD_TUNNEL6;
+	dev->hard_header_len = LL_MAX_HEADER + t_hlen;
+	dev->mtu = ETH_DATA_LEN - t_hlen;
+	if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
+		dev->mtu -= 8;
 
 	return 0;