netfilter: x_tables: use NFPROTO_* in extensions
[linux-2.6.git] / net / ipv4 / xfrm4_mode_tunnel.c
1 /*
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
17 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
18 {
19         struct iphdr *inner_iph = ipip_hdr(skb);
20
21         if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
22                 IP_ECN_set_ce(inner_iph);
23 }
24
25 /* Add encapsulation header.
26  *
27  * The top IP header will be constructed per RFC 2401.
28  */
29 static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
30 {
31         struct dst_entry *dst = skb->dst;
32         struct iphdr *top_iph;
33         int flags;
34
35         skb_set_network_header(skb, -x->props.header_len);
36         skb->mac_header = skb->network_header +
37                           offsetof(struct iphdr, protocol);
38         skb->transport_header = skb->network_header + sizeof(*top_iph);
39         top_iph = ip_hdr(skb);
40
41         top_iph->ihl = 5;
42         top_iph->version = 4;
43
44         top_iph->protocol = xfrm_af2proto(skb->dst->ops->family);
45
46         /* DS disclosed */
47         top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos,
48                                             XFRM_MODE_SKB_CB(skb)->tos);
49
50         flags = x->props.flags;
51         if (flags & XFRM_STATE_NOECN)
52                 IP_ECN_clear(top_iph);
53
54         top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
55                 0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
56         ip_select_ident(top_iph, dst->child, NULL);
57
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;
62
63         return 0;
64 }
65
66 static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
67 {
68         const unsigned char *old_mac;
69         int err = -EINVAL;
70
71         if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
72                 goto out;
73
74         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
81         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
86         old_mac = skb_mac_header(skb);
87         skb_set_mac_header(skb, -skb->mac_len);
88         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
89         skb_reset_network_header(skb);
90         err = 0;
91
92 out:
93         return err;
94 }
95
96 static struct xfrm_mode xfrm4_tunnel_mode = {
97         .input2 = xfrm4_mode_tunnel_input,
98         .input = xfrm_prepare_input,
99         .output2 = xfrm4_mode_tunnel_output,
100         .output = xfrm4_prepare_output,
101         .owner = THIS_MODULE,
102         .encap = XFRM_MODE_TUNNEL,
103         .flags = XFRM_MODE_FLAG_TUNNEL,
104 };
105
106 static int __init xfrm4_mode_tunnel_init(void)
107 {
108         return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
109 }
110
111 static void __exit xfrm4_mode_tunnel_exit(void)
112 {
113         int err;
114
115         err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
116         BUG_ON(err);
117 }
118
119 module_init(xfrm4_mode_tunnel_init);
120 module_exit(xfrm4_mode_tunnel_exit);
121 MODULE_LICENSE("GPL");
122 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);