[NETFILTER]: Remove some EXPERIMENTAL dependencies
[linux-2.6] / net / ipv4 / xfrm4_mode_beet.c
1 /*
2  * xfrm4_mode_beet.c - BEET mode encapsulation for IPv4.
3  *
4  * Copyright (c) 2006 Diego Beltrami <diego.beltrami@gmail.com>
5  *                    Miika Komu     <miika@iki.fi>
6  *                    Herbert Xu     <herbert@gondor.apana.org.au>
7  *                    Abhinav Pathak <abhinav.pathak@hiit.fi>
8  *                    Jeff Ahrenholz <ahrenholz@gmail.com>
9  */
10
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/skbuff.h>
15 #include <linux/stringify.h>
16 #include <net/dst.h>
17 #include <net/ip.h>
18 #include <net/xfrm.h>
19
20 static void xfrm4_beet_make_header(struct sk_buff *skb)
21 {
22         struct iphdr *iph = ip_hdr(skb);
23
24         iph->ihl = 5;
25         iph->version = 4;
26
27         iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
28         iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
29
30         iph->id = XFRM_MODE_SKB_CB(skb)->id;
31         iph->frag_off = XFRM_MODE_SKB_CB(skb)->frag_off;
32         iph->ttl = XFRM_MODE_SKB_CB(skb)->ttl;
33 }
34
35 /* Add encapsulation header.
36  *
37  * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
38  */
39 static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
40 {
41         struct ip_beet_phdr *ph;
42         struct iphdr *iph, *top_iph;
43         int hdrlen, optlen;
44
45         iph = ip_hdr(skb);
46
47         hdrlen = 0;
48         optlen = iph->ihl * 4 - sizeof(*iph);
49         if (unlikely(optlen))
50                 hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
51
52         skb_set_network_header(skb, IPV4_BEET_PHMAXLEN - x->props.header_len -
53                                     hdrlen);
54         skb->mac_header = skb->network_header +
55                           offsetof(struct iphdr, protocol);
56         skb->transport_header = skb->network_header + sizeof(*iph);
57
58         xfrm4_beet_make_header(skb);
59
60         ph = (struct ip_beet_phdr *)__skb_pull(skb, sizeof(*iph) - hdrlen);
61
62         top_iph = ip_hdr(skb);
63
64         if (unlikely(optlen)) {
65                 BUG_ON(optlen < 0);
66
67                 ph->padlen = 4 - (optlen & 4);
68                 ph->hdrlen = optlen / 8;
69                 ph->nexthdr = top_iph->protocol;
70                 if (ph->padlen)
71                         memset(ph + 1, IPOPT_NOP, ph->padlen);
72
73                 top_iph->protocol = IPPROTO_BEETPH;
74                 top_iph->ihl = sizeof(struct iphdr) / 4;
75         }
76
77         top_iph->saddr = x->props.saddr.a4;
78         top_iph->daddr = x->id.daddr.a4;
79
80         return 0;
81 }
82
83 static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
84 {
85         struct iphdr *iph;
86         int optlen = 0;
87         int err = -EINVAL;
88
89         if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
90                 struct ip_beet_phdr *ph;
91                 int phlen;
92
93                 if (!pskb_may_pull(skb, sizeof(*ph)))
94                         goto out;
95
96                 ph = (struct ip_beet_phdr *)skb->data;
97
98                 phlen = sizeof(*ph) + ph->padlen;
99                 optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
100                 if (optlen < 0 || optlen & 3 || optlen > 250)
101                         goto out;
102
103                 XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr;
104
105                 if (!pskb_may_pull(skb, phlen));
106                         goto out;
107                 __skb_pull(skb, phlen);
108         }
109
110         skb_push(skb, sizeof(*iph));
111         skb_reset_network_header(skb);
112
113         memmove(skb->data - skb->mac_len, skb_mac_header(skb),
114                 skb->mac_len);
115         skb_set_mac_header(skb, -skb->mac_len);
116
117         xfrm4_beet_make_header(skb);
118
119         iph = ip_hdr(skb);
120
121         iph->ihl += optlen / 4;
122         iph->tot_len = htons(skb->len);
123         iph->daddr = x->sel.daddr.a4;
124         iph->saddr = x->sel.saddr.a4;
125         iph->check = 0;
126         iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
127         err = 0;
128 out:
129         return err;
130 }
131
132 static struct xfrm_mode xfrm4_beet_mode = {
133         .input2 = xfrm4_beet_input,
134         .input = xfrm_prepare_input,
135         .output2 = xfrm4_beet_output,
136         .output = xfrm4_prepare_output,
137         .owner = THIS_MODULE,
138         .encap = XFRM_MODE_BEET,
139         .flags = XFRM_MODE_FLAG_TUNNEL,
140 };
141
142 static int __init xfrm4_beet_init(void)
143 {
144         return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
145 }
146
147 static void __exit xfrm4_beet_exit(void)
148 {
149         int err;
150
151         err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
152         BUG_ON(err);
153 }
154
155 module_init(xfrm4_beet_init);
156 module_exit(xfrm4_beet_exit);
157 MODULE_LICENSE("GPL");
158 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);