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	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
53		dsfield = 0;
54	else
55		dsfield = XFRM_MODE_SKB_CB(skb)->tos;
56	dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
57	if (x->props.flags & XFRM_STATE_NOECN)
58		dsfield &= ~INET_ECN_MASK;
59	ipv6_change_dsfield(top_iph, 0, dsfield);
60	top_iph->hop_limit = ip6_dst_hoplimit(dst->child);
61	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
62	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
63	return 0;
64}
65
66#define for_each_input_rcu(head, handler)	\
67	for (handler = rcu_dereference(head);	\
68	     handler != NULL;			\
69	     handler = rcu_dereference(handler->next))
70
71
72static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
73{
74	int err = -EINVAL;
75
76	if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
77		goto out;
78	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
79		goto out;
80
81	err = skb_unclone(skb, GFP_ATOMIC);
82	if (err)
83		goto out;
84
85	if (x->props.flags & XFRM_STATE_DECAP_DSCP)
86		ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
87			       ipipv6_hdr(skb));
88	if (!(x->props.flags & XFRM_STATE_NOECN))
89		ipip6_ecn_decapsulate(skb);
90
91	skb_reset_network_header(skb);
92	skb_mac_header_rebuild(skb);
93
94	err = 0;
95
96out:
97	return err;
98}
99
100static struct xfrm_mode xfrm6_tunnel_mode = {
101	.input2 = xfrm6_mode_tunnel_input,
102	.input = xfrm_prepare_input,
103	.output2 = xfrm6_mode_tunnel_output,
104	.output = xfrm6_prepare_output,
105	.owner = THIS_MODULE,
106	.encap = XFRM_MODE_TUNNEL,
107	.flags = XFRM_MODE_FLAG_TUNNEL,
108};
109
110static int __init xfrm6_mode_tunnel_init(void)
111{
112	return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
113}
114
115static void __exit xfrm6_mode_tunnel_exit(void)
116{
117	int err;
118
119	err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
120	BUG_ON(err);
121}
122
123module_init(xfrm6_mode_tunnel_init);
124module_exit(xfrm6_mode_tunnel_exit);
125MODULE_LICENSE("GPL");
126MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);
127