blob: 8dee617ee900662ddac773b7350fe0cc23745692 [file] [log] [blame]
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 Melob0061ce2007-04-25 18:02:22 -070019 struct iphdr *inner_iph = ipip_hdr(skb);
Herbert Xub59f45d2006-05-27 23:05:54 -070020
Herbert Xu227620e2007-11-13 21:41:28 -080021 if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
Herbert Xub59f45d2006-05-27 23:05:54 -070022 IP_ECN_set_ce(inner_iph);
23}
24
25/* Add encapsulation header.
26 *
Herbert Xuceb1eec82007-10-10 15:45:52 -070027 * The top IP header will be constructed per RFC 2401.
Herbert Xub59f45d2006-05-27 23:05:54 -070028 */
Herbert Xu195ad6a2007-12-20 13:53:40 -080029static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
Herbert Xub59f45d2006-05-27 23:05:54 -070030{
31 struct dst_entry *dst = skb->dst;
Herbert Xu36cf9ac2007-11-13 21:40:52 -080032 struct iphdr *top_iph;
Herbert Xub59f45d2006-05-27 23:05:54 -070033 int flags;
34
Herbert Xu7b277b12007-10-10 15:44:06 -070035 skb_set_network_header(skb, -x->props.header_len);
Herbert Xu37fedd32007-10-10 15:44:44 -070036 skb->mac_header = skb->network_header +
37 offsetof(struct iphdr, protocol);
Herbert Xu36cf9ac2007-11-13 21:40:52 -080038 skb->transport_header = skb->network_header + sizeof(*top_iph);
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -070039 top_iph = ip_hdr(skb);
Herbert Xub59f45d2006-05-27 23:05:54 -070040
41 top_iph->ihl = 5;
42 top_iph->version = 4;
43
Herbert Xu36cf9ac2007-11-13 21:40:52 -080044 top_iph->protocol = x->inner_mode->afinfo->proto;
Miika Komuc82f9632007-02-06 14:27:02 -080045
46 /* DS disclosed */
Herbert Xu36cf9ac2007-11-13 21:40:52 -080047 top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos,
48 XFRM_MODE_SKB_CB(skb)->tos);
Miika Komuc82f9632007-02-06 14:27:02 -080049
Herbert Xu36cf9ac2007-11-13 21:40:52 -080050 flags = x->props.flags;
Herbert Xub59f45d2006-05-27 23:05:54 -070051 if (flags & XFRM_STATE_NOECN)
52 IP_ECN_clear(top_iph);
53
Herbert Xu36cf9ac2007-11-13 21:40:52 -080054 top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
55 0 : XFRM_MODE_SKB_CB(skb)->frag_off;
56 ip_select_ident(top_iph, dst->child, NULL);
Herbert Xub59f45d2006-05-27 23:05:54 -070057
58 top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
59
60 top_iph->saddr = x->props.saddr.a4;
61 top_iph->daddr = x->id.daddr.a4;
Herbert Xub59f45d2006-05-27 23:05:54 -070062
Herbert Xub59f45d2006-05-27 23:05:54 -070063 return 0;
64}
65
Herbert Xu195ad6a2007-12-20 13:53:40 -080066static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
Herbert Xub59f45d2006-05-27 23:05:54 -070067{
Arnaldo Carvalho de Melo39f69c62007-03-10 12:40:27 -030068 const unsigned char *old_mac;
Herbert Xub59f45d2006-05-27 23:05:54 -070069 int err = -EINVAL;
70
Herbert Xu227620e2007-11-13 21:41:28 -080071 if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
72 goto out;
Miika Komuc82f9632007-02-06 14:27:02 -080073
Herbert Xub59f45d2006-05-27 23:05:54 -070074 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
75 goto out;
76
77 if (skb_cloned(skb) &&
78 (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
79 goto out;
80
Herbert Xu227620e2007-11-13 21:41:28 -080081 if (x->props.flags & XFRM_STATE_DECAP_DSCP)
82 ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb));
83 if (!(x->props.flags & XFRM_STATE_NOECN))
84 ipip_ecn_decapsulate(skb);
85
Arnaldo Carvalho de Melo98e399f2007-03-19 15:33:04 -070086 old_mac = skb_mac_header(skb);
Arnaldo Carvalho de Melo39f69c62007-03-10 12:40:27 -030087 skb_set_mac_header(skb, -skb->mac_len);
Arnaldo Carvalho de Melo98e399f2007-03-19 15:33:04 -070088 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
Arnaldo Carvalho de Meloc1d2bbe2007-04-10 20:45:18 -070089 skb_reset_network_header(skb);
Herbert Xub59f45d2006-05-27 23:05:54 -070090 err = 0;
91
92out:
93 return err;
94}
95
96static struct xfrm_mode xfrm4_tunnel_mode = {
Herbert Xu195ad6a2007-12-20 13:53:40 -080097 .input2 = xfrm4_mode_tunnel_input,
Herbert Xu227620e2007-11-13 21:41:28 -080098 .input = xfrm_prepare_input,
Herbert Xu195ad6a2007-12-20 13:53:40 -080099 .output2 = xfrm4_mode_tunnel_output,
Herbert Xu36cf9ac2007-11-13 21:40:52 -0800100 .output = xfrm4_prepare_output,
Herbert Xub59f45d2006-05-27 23:05:54 -0700101 .owner = THIS_MODULE,
102 .encap = XFRM_MODE_TUNNEL,
Herbert Xu1bfcb102007-10-17 21:31:50 -0700103 .flags = XFRM_MODE_FLAG_TUNNEL,
Herbert Xub59f45d2006-05-27 23:05:54 -0700104};
105
Herbert Xu195ad6a2007-12-20 13:53:40 -0800106static int __init xfrm4_mode_tunnel_init(void)
Herbert Xub59f45d2006-05-27 23:05:54 -0700107{
108 return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
109}
110
Herbert Xu195ad6a2007-12-20 13:53:40 -0800111static void __exit xfrm4_mode_tunnel_exit(void)
Herbert Xub59f45d2006-05-27 23:05:54 -0700112{
113 int err;
114
115 err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
116 BUG_ON(err);
117}
118
Herbert Xu195ad6a2007-12-20 13:53:40 -0800119module_init(xfrm4_mode_tunnel_init);
120module_exit(xfrm4_mode_tunnel_exit);
Herbert Xub59f45d2006-05-27 23:05:54 -0700121MODULE_LICENSE("GPL");
122MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);