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/ipv6.h>
18#include <net/xfrm.h>
19
20static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
21{
22	struct ipv6hdr *outer_iph = ipv6_hdr(skb);
23	struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
24
25	if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
26		IP6_ECN_set_ce(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	dsfield = XFRM_MODE_SKB_CB(skb)->tos;
52	dsfield = INET_ECN_encapsulate(dsfield, dsfield);
53	if (x->props.flags & XFRM_STATE_NOECN)
54		dsfield &= ~INET_ECN_MASK;
55	ipv6_change_dsfield(top_iph, 0, dsfield);
56	top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
57	ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
58	ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
59	return 0;
60}
61
62static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
63{
64	int err = -EINVAL;
65	const unsigned char *old_mac;
66
67	if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
68		goto out;
69	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
70		goto out;
71
72	if (skb_cloned(skb) &&
73	    (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
74		goto out;
75
76	if (x->props.flags & XFRM_STATE_DECAP_DSCP)
77		ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
78			       ipipv6_hdr(skb));
79	if (!(x->props.flags & XFRM_STATE_NOECN))
80		ipip6_ecn_decapsulate(skb);
81
82	old_mac = skb_mac_header(skb);
83	skb_set_mac_header(skb, -skb->mac_len);
84	memmove(skb_mac_header(skb), old_mac, skb->mac_len);
85	skb_reset_network_header(skb);
86	err = 0;
87
88out:
89	return err;
90}
91
92static struct xfrm_mode xfrm6_tunnel_mode = {
93	.input2 = xfrm6_mode_tunnel_input,
94	.input = xfrm_prepare_input,
95	.output2 = xfrm6_mode_tunnel_output,
96	.output = xfrm6_prepare_output,
97	.owner = THIS_MODULE,
98	.encap = XFRM_MODE_TUNNEL,
99	.flags = XFRM_MODE_FLAG_TUNNEL,
100};
101
102static int __init xfrm6_mode_tunnel_init(void)
103{
104	return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
105}
106
107static void __exit xfrm6_mode_tunnel_exit(void)
108{
109	int err;
110
111	err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
112	BUG_ON(err);
113}
114
115module_init(xfrm6_mode_tunnel_init);
116module_exit(xfrm6_mode_tunnel_exit);
117MODULE_LICENSE("GPL");
118MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);
119