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	const struct ipv6hdr *outer_iph = ipv6_hdr(skb);
 24	struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
 25
 26	if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
 27		IP6_ECN_set_ce(inner_iph);
 28}
 29
 30/* Add encapsulation header.
 31 *
 32 * The top IP header will be constructed per RFC 2401.
 33 */
 34static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 35{
 36	struct dst_entry *dst = skb_dst(skb);
 37	struct ipv6hdr *top_iph;
 38	int dsfield;
 39
 40	skb_set_network_header(skb, -x->props.header_len);
 41	skb->mac_header = skb->network_header +
 42			  offsetof(struct ipv6hdr, nexthdr);
 43	skb->transport_header = skb->network_header + sizeof(*top_iph);
 44	top_iph = ipv6_hdr(skb);
 45
 46	top_iph->version = 6;
 47
 48	memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
 49	       sizeof(top_iph->flow_lbl));
 50	top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
 51
 52	dsfield = XFRM_MODE_SKB_CB(skb)->tos;
 53	dsfield = INET_ECN_encapsulate(dsfield, dsfield);
 54	if (x->props.flags & XFRM_STATE_NOECN)
 55		dsfield &= ~INET_ECN_MASK;
 56	ipv6_change_dsfield(top_iph, 0, dsfield);
 57	top_iph->hop_limit = ip6_dst_hoplimit(dst->child);
 58	ipv6_addr_copy(&top_iph->saddr, (const struct in6_addr *)&x->props.saddr);
 59	ipv6_addr_copy(&top_iph->daddr, (const struct in6_addr *)&x->id.daddr);
 60	return 0;
 61}
 62
 63static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 64{
 65	int err = -EINVAL;
 66	const unsigned char *old_mac;
 67
 68	if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
 69		goto out;
 70	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 71		goto out;
 72
 73	if (skb_cloned(skb) &&
 74	    (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
 75		goto out;
 76
 77	if (x->props.flags & XFRM_STATE_DECAP_DSCP)
 78		ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
 79			       ipipv6_hdr(skb));
 80	if (!(x->props.flags & XFRM_STATE_NOECN))
 81		ipip6_ecn_decapsulate(skb);
 82
 83	old_mac = skb_mac_header(skb);
 84	skb_set_mac_header(skb, -skb->mac_len);
 85	memmove(skb_mac_header(skb), old_mac, skb->mac_len);
 86	skb_reset_network_header(skb);
 87	err = 0;
 88
 89out:
 90	return err;
 91}
 92
 93static struct xfrm_mode xfrm6_tunnel_mode = {
 94	.input2 = xfrm6_mode_tunnel_input,
 95	.input = xfrm_prepare_input,
 96	.output2 = xfrm6_mode_tunnel_output,
 97	.output = xfrm6_prepare_output,
 98	.owner = THIS_MODULE,
 99	.encap = XFRM_MODE_TUNNEL,
100	.flags = XFRM_MODE_FLAG_TUNNEL,
101};
102
103static int __init xfrm6_mode_tunnel_init(void)
104{
105	return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
106}
107
108static void __exit xfrm6_mode_tunnel_exit(void)
109{
110	int err;
111
112	err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
113	BUG_ON(err);
114}
115
116module_init(xfrm6_mode_tunnel_init);
117module_exit(xfrm6_mode_tunnel_exit);
118MODULE_LICENSE("GPL");
119MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);