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Herbert Xub59f45d2006-05-27 23:05:54 -07001/*
2 * xfrm4_mode_tunnel.c - Tunnel mode encapsulation for IPv4.
3 *
4 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
5 */
6
7#include <linux/init.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/stringify.h>
12#include <net/dst.h>
13#include <net/inet_ecn.h>
14#include <net/ip.h>
15#include <net/xfrm.h>
16
17static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
18{
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070019 struct iphdr *outer_iph = ip_hdr(skb);
Arnaldo Carvalho de Melob0061ce2007-04-25 18:02:22 -070020 struct iphdr *inner_iph = ipip_hdr(skb);
Herbert Xub59f45d2006-05-27 23:05:54 -070021
22 if (INET_ECN_is_ce(outer_iph->tos))
23 IP_ECN_set_ce(inner_iph);
24}
25
Miika Komuc82f9632007-02-06 14:27:02 -080026static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
27{
28 if (INET_ECN_is_ce(iph->tos))
Arnaldo Carvalho de Melo0660e032007-04-25 17:54:47 -070029 IP6_ECN_set_ce(ipv6_hdr(skb));
Miika Komuc82f9632007-02-06 14:27:02 -080030}
31
Herbert Xub59f45d2006-05-27 23:05:54 -070032/* Add encapsulation header.
33 *
34 * The top IP header will be constructed per RFC 2401. The following fields
35 * in it shall be filled in by x->type->output:
36 * tot_len
37 * check
38 *
39 * On exit, skb->h will be set to the start of the payload to be processed
40 * by x->type->output and skb->nh will be set to the top IP header.
41 */
Jamal Hadi Salimeb878e82006-08-31 17:42:59 -070042static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
Herbert Xub59f45d2006-05-27 23:05:54 -070043{
44 struct dst_entry *dst = skb->dst;
Miika Komuc82f9632007-02-06 14:27:02 -080045 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
Herbert Xub59f45d2006-05-27 23:05:54 -070046 struct iphdr *iph, *top_iph;
47 int flags;
48
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070049 iph = ip_hdr(skb);
Arnaldo Carvalho de Melob0e380b2007-04-10 21:21:55 -070050 skb->transport_header = skb->network_header;
Herbert Xub59f45d2006-05-27 23:05:54 -070051
Herbert Xu7b277b12007-10-10 15:44:06 -070052 skb_set_network_header(skb, -x->props.header_len);
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070053 top_iph = ip_hdr(skb);
Herbert Xub59f45d2006-05-27 23:05:54 -070054
55 top_iph->ihl = 5;
56 top_iph->version = 4;
57
Herbert Xub59f45d2006-05-27 23:05:54 -070058 flags = x->props.flags;
Miika Komuc82f9632007-02-06 14:27:02 -080059
60 /* DS disclosed */
61 if (xdst->route->ops->family == AF_INET) {
62 top_iph->protocol = IPPROTO_IPIP;
63 top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
64 top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
65 0 : (iph->frag_off & htons(IP_DF));
66 }
67#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
68 else {
69 struct ipv6hdr *ipv6h = (struct ipv6hdr*)iph;
70 top_iph->protocol = IPPROTO_IPV6;
71 top_iph->tos = INET_ECN_encapsulate(iph->tos, ipv6_get_dsfield(ipv6h));
72 top_iph->frag_off = 0;
73 }
74#endif
75
Herbert Xub59f45d2006-05-27 23:05:54 -070076 if (flags & XFRM_STATE_NOECN)
77 IP_ECN_clear(top_iph);
78
Herbert Xub59f45d2006-05-27 23:05:54 -070079 if (!top_iph->frag_off)
80 __ip_select_ident(top_iph, dst->child, 0);
81
82 top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
83
84 top_iph->saddr = x->props.saddr.a4;
85 top_iph->daddr = x->id.daddr.a4;
Herbert Xub59f45d2006-05-27 23:05:54 -070086
Kazunori MIYAZAWAf282d452007-05-29 13:03:17 -070087 skb->protocol = htons(ETH_P_IP);
88
Herbert Xub59f45d2006-05-27 23:05:54 -070089 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
90 return 0;
91}
92
93static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
94{
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070095 struct iphdr *iph = ip_hdr(skb);
Arnaldo Carvalho de Melo39f69c62007-03-10 12:40:27 -030096 const unsigned char *old_mac;
Herbert Xub59f45d2006-05-27 23:05:54 -070097 int err = -EINVAL;
98
Stephen Hemminger132adf52007-03-08 20:44:43 -080099 switch (iph->protocol){
Miika Komuc82f9632007-02-06 14:27:02 -0800100 case IPPROTO_IPIP:
Patrick McHardye2e01bf2007-02-12 20:27:10 -0800101 break;
Miika Komuc82f9632007-02-06 14:27:02 -0800102#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
103 case IPPROTO_IPV6:
104 break;
105#endif
106 default:
107 goto out;
108 }
109
Herbert Xub59f45d2006-05-27 23:05:54 -0700110 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
111 goto out;
112
113 if (skb_cloned(skb) &&
114 (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
115 goto out;
116
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700117 iph = ip_hdr(skb);
Miika Komuc82f9632007-02-06 14:27:02 -0800118 if (iph->protocol == IPPROTO_IPIP) {
119 if (x->props.flags & XFRM_STATE_DECAP_DSCP)
Arnaldo Carvalho de Melob0061ce2007-04-25 18:02:22 -0700120 ipv4_copy_dscp(iph, ipip_hdr(skb));
Miika Komuc82f9632007-02-06 14:27:02 -0800121 if (!(x->props.flags & XFRM_STATE_NOECN))
122 ipip_ecn_decapsulate(skb);
123 }
124#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
125 else {
126 if (!(x->props.flags & XFRM_STATE_NOECN))
127 ipip6_ecn_decapsulate(iph, skb);
128 skb->protocol = htons(ETH_P_IPV6);
129 }
130#endif
Arnaldo Carvalho de Melo98e399f2007-03-19 15:33:04 -0700131 old_mac = skb_mac_header(skb);
Arnaldo Carvalho de Melo39f69c62007-03-10 12:40:27 -0300132 skb_set_mac_header(skb, -skb->mac_len);
Arnaldo Carvalho de Melo98e399f2007-03-19 15:33:04 -0700133 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
Arnaldo Carvalho de Meloc1d2bbe2007-04-10 20:45:18 -0700134 skb_reset_network_header(skb);
Herbert Xub59f45d2006-05-27 23:05:54 -0700135 err = 0;
136
137out:
138 return err;
139}
140
141static struct xfrm_mode xfrm4_tunnel_mode = {
142 .input = xfrm4_tunnel_input,
143 .output = xfrm4_tunnel_output,
144 .owner = THIS_MODULE,
145 .encap = XFRM_MODE_TUNNEL,
146};
147
148static int __init xfrm4_tunnel_init(void)
149{
150 return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
151}
152
153static void __exit xfrm4_tunnel_exit(void)
154{
155 int err;
156
157 err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
158 BUG_ON(err);
159}
160
161module_init(xfrm4_tunnel_init);
162module_exit(xfrm4_tunnel_exit);
163MODULE_LICENSE("GPL");
164MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);