Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[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/gfp.h>
8 #include <linux/init.h>
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
12 #include <linux/stringify.h>
13 #include <net/dst.h>
14 #include <net/inet_ecn.h>
15 #include <net/ip.h>
16 #include <net/xfrm.h>
17
18 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
19 {
20         struct iphdr *inner_iph = ipip_hdr(skb);
21
22         if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
23                 IP_ECN_set_ce(inner_iph);
24 }
25
26 /* Add encapsulation header.
27  *
28  * The top IP header will be constructed per RFC 2401.
29  */
30 static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
31 {
32         struct dst_entry *dst = skb_dst(skb);
33         struct iphdr *top_iph;
34         int flags;
35
36         skb_set_network_header(skb, -x->props.header_len);
37         skb->mac_header = skb->network_header +
38                           offsetof(struct iphdr, protocol);
39         skb->transport_header = skb->network_header + sizeof(*top_iph);
40         top_iph = ip_hdr(skb);
41
42         top_iph->ihl = 5;
43         top_iph->version = 4;
44
45         top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
46
47         /* DS disclosed */
48         top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos,
49                                             XFRM_MODE_SKB_CB(skb)->tos);
50
51         flags = x->props.flags;
52         if (flags & XFRM_STATE_NOECN)
53                 IP_ECN_clear(top_iph);
54
55         top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
56                 0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
57         ip_select_ident(top_iph, dst->child, NULL);
58
59         top_iph->ttl = ip4_dst_hoplimit(dst->child);
60
61         top_iph->saddr = x->props.saddr.a4;
62         top_iph->daddr = x->id.daddr.a4;
63
64         return 0;
65 }
66
67 static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
68 {
69         const unsigned char *old_mac;
70         int err = -EINVAL;
71
72         if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
73                 goto out;
74
75         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
76                 goto out;
77
78         if (skb_cloned(skb) &&
79             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
80                 goto out;
81
82         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
83                 ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb));
84         if (!(x->props.flags & XFRM_STATE_NOECN))
85                 ipip_ecn_decapsulate(skb);
86
87         old_mac = skb_mac_header(skb);
88         skb_set_mac_header(skb, -skb->mac_len);
89         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
90         skb_reset_network_header(skb);
91         err = 0;
92
93 out:
94         return err;
95 }
96
97 static struct xfrm_mode xfrm4_tunnel_mode = {
98         .input2 = xfrm4_mode_tunnel_input,
99         .input = xfrm_prepare_input,
100         .output2 = xfrm4_mode_tunnel_output,
101         .output = xfrm4_prepare_output,
102         .owner = THIS_MODULE,
103         .encap = XFRM_MODE_TUNNEL,
104         .flags = XFRM_MODE_FLAG_TUNNEL,
105 };
106
107 static int __init xfrm4_mode_tunnel_init(void)
108 {
109         return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
110 }
111
112 static void __exit xfrm4_mode_tunnel_exit(void)
113 {
114         int err;
115
116         err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
117         BUG_ON(err);
118 }
119
120 module_init(xfrm4_mode_tunnel_init);
121 module_exit(xfrm4_mode_tunnel_exit);
122 MODULE_LICENSE("GPL");
123 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);