1/*
  2 * xfrm6_mode_tunnel.c - Tunnel mode encapsulation for IPv6.
  3 *
  4 * Copyright (C) 2002 USAGI/WIDE Project
  5 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
  6 */
  7
  8#include <linux/gfp.h>
  9#include <linux/init.h>
 10#include <linux/kernel.h>
 11#include <linux/module.h>
 12#include <linux/skbuff.h>
 13#include <linux/stringify.h>
 14#include <net/dsfield.h>
 15#include <net/dst.h>
 16#include <net/inet_ecn.h>
 17#include <net/ip6_route.h>
 18#include <net/ipv6.h>
 19#include <net/xfrm.h>
 20
 21static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
 22{
 23	struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
 24
 25	if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
 26		IP6_ECN_set_ce(skb, inner_iph);
 27}
 28
 29/* Add encapsulation header.
 30 *
 31 * The top IP header will be constructed per RFC 2401.
 32 */
 33static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 34{
 35	struct dst_entry *dst = skb_dst(skb);
 36	struct ipv6hdr *top_iph;
 37	int dsfield;
 38
 39	skb_set_network_header(skb, -x->props.header_len);
 40	skb->mac_header = skb->network_header +
 41			  offsetof(struct ipv6hdr, nexthdr);
 42	skb->transport_header = skb->network_header + sizeof(*top_iph);
 43	top_iph = ipv6_hdr(skb);
 44
 45	top_iph->version = 6;
 46
 47	memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
 48	       sizeof(top_iph->flow_lbl));
 49	top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
 50
 51	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
 52		dsfield = 0;
 53	else
 54		dsfield = XFRM_MODE_SKB_CB(skb)->tos;
 55	dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
 56	if (x->props.flags & XFRM_STATE_NOECN)
 57		dsfield &= ~INET_ECN_MASK;
 58	ipv6_change_dsfield(top_iph, 0, dsfield);
 59	top_iph->hop_limit = ip6_dst_hoplimit(dst->child);
 60	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
 61	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
 62	return 0;
 63}
 64
 65#define for_each_input_rcu(head, handler)	\
 66	for (handler = rcu_dereference(head);	\
 67	     handler != NULL;			\
 68	     handler = rcu_dereference(handler->next))
 69
 70
 71static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 72{
 73	int err = -EINVAL;
 74
 75	if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
 76		goto out;
 77	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 78		goto out;
 79
 80	err = skb_unclone(skb, GFP_ATOMIC);
 81	if (err)
 82		goto out;
 83
 84	if (x->props.flags & XFRM_STATE_DECAP_DSCP)
 85		ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
 86			       ipipv6_hdr(skb));
 87	if (!(x->props.flags & XFRM_STATE_NOECN))
 88		ipip6_ecn_decapsulate(skb);
 89
 90	skb_reset_network_header(skb);
 91	skb_mac_header_rebuild(skb);
 92
 93	err = 0;
 94
 95out:
 96	return err;
 97}
 98
 99static struct xfrm_mode xfrm6_tunnel_mode = {
100	.input2 = xfrm6_mode_tunnel_input,
101	.input = xfrm_prepare_input,
102	.output2 = xfrm6_mode_tunnel_output,
103	.output = xfrm6_prepare_output,
104	.owner = THIS_MODULE,
105	.encap = XFRM_MODE_TUNNEL,
106	.flags = XFRM_MODE_FLAG_TUNNEL,
107};
108
109static int __init xfrm6_mode_tunnel_init(void)
110{
111	return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
112}
113
114static void __exit xfrm6_mode_tunnel_exit(void)
115{
116	int err;
117
118	err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
119	BUG_ON(err);
120}
121
122module_init(xfrm6_mode_tunnel_init);
123module_exit(xfrm6_mode_tunnel_exit);
124MODULE_LICENSE("GPL");
125MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);