Merge branch 'tj-upstream-fixes' of git://htj.dyndns.org/libata-tj into upstream...
[linux-2.6] / 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 *outer_iph = skb->nh.iph;
20         struct iphdr *inner_iph = skb->h.ipiph;
21
22         if (INET_ECN_is_ce(outer_iph->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.  The following fields
29  * in it shall be filled in by x->type->output:
30  *      tot_len
31  *      check
32  *
33  * On exit, skb->h will be set to the start of the payload to be processed
34  * by x->type->output and skb->nh will be set to the top IP header.
35  */
36 static int xfrm4_tunnel_output(struct sk_buff *skb)
37 {
38         struct dst_entry *dst = skb->dst;
39         struct xfrm_state *x = dst->xfrm;
40         struct iphdr *iph, *top_iph;
41         int flags;
42
43         iph = skb->nh.iph;
44         skb->h.ipiph = iph;
45
46         skb->nh.raw = skb_push(skb, x->props.header_len);
47         top_iph = skb->nh.iph;
48
49         top_iph->ihl = 5;
50         top_iph->version = 4;
51
52         /* DS disclosed */
53         top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
54
55         flags = x->props.flags;
56         if (flags & XFRM_STATE_NOECN)
57                 IP_ECN_clear(top_iph);
58
59         top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
60                 0 : (iph->frag_off & htons(IP_DF));
61         if (!top_iph->frag_off)
62                 __ip_select_ident(top_iph, dst->child, 0);
63
64         top_iph->ttl = dst_metric(dst->child, RTAX_HOPLIMIT);
65
66         top_iph->saddr = x->props.saddr.a4;
67         top_iph->daddr = x->id.daddr.a4;
68         top_iph->protocol = IPPROTO_IPIP;
69
70         memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
71         return 0;
72 }
73
74 static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
75 {
76         struct iphdr *iph = skb->nh.iph;
77         int err = -EINVAL;
78
79         if (iph->protocol != IPPROTO_IPIP)
80                 goto out;
81         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
82                 goto out;
83
84         if (skb_cloned(skb) &&
85             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
86                 goto out;
87
88         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
89                 ipv4_copy_dscp(iph, skb->h.ipiph);
90         if (!(x->props.flags & XFRM_STATE_NOECN))
91                 ipip_ecn_decapsulate(skb);
92         skb->mac.raw = memmove(skb->data - skb->mac_len,
93                                skb->mac.raw, skb->mac_len);
94         skb->nh.raw = skb->data;
95         err = 0;
96
97 out:
98         return err;
99 }
100
101 static struct xfrm_mode xfrm4_tunnel_mode = {
102         .input = xfrm4_tunnel_input,
103         .output = xfrm4_tunnel_output,
104         .owner = THIS_MODULE,
105         .encap = XFRM_MODE_TUNNEL,
106 };
107
108 static int __init xfrm4_tunnel_init(void)
109 {
110         return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
111 }
112
113 static void __exit xfrm4_tunnel_exit(void)
114 {
115         int err;
116
117         err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
118         BUG_ON(err);
119 }
120
121 module_init(xfrm4_tunnel_init);
122 module_exit(xfrm4_tunnel_exit);
123 MODULE_LICENSE("GPL");
124 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);