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 *top_iph;
43 int hdrlen, optlen;
44
45 hdrlen = 0;
46 optlen = XFRM_MODE_SKB_CB(skb)->optlen;
47 if (unlikely(optlen))
48 hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
49
50 skb_set_network_header(skb, IPV4_BEET_PHMAXLEN - x->props.header_len -
51 hdrlen);
52 skb->mac_header = skb->network_header +
53 offsetof(struct iphdr, protocol);
54 skb->transport_header = skb->network_header + sizeof(*top_iph);
55
56 xfrm4_beet_make_header(skb);
57
58 ph = (struct ip_beet_phdr *)
59 __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
60
61 top_iph = ip_hdr(skb);
62
63 if (unlikely(optlen)) {
64 BUG_ON(optlen < 0);
65
66 ph->padlen = 4 - (optlen & 4);
67 ph->hdrlen = optlen / 8;
68 ph->nexthdr = top_iph->protocol;
69 if (ph->padlen)
70 memset(ph + 1, IPOPT_NOP, ph->padlen);
71
72 top_iph->protocol = IPPROTO_BEETPH;
73 top_iph->ihl = sizeof(struct iphdr) / 4;
74 }
75
76 top_iph->saddr = x->props.saddr.a4;
77 top_iph->daddr = x->id.daddr.a4;
78
79 return 0;
80 }
81
82 static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
83 {
84 struct iphdr *iph;
85 int optlen = 0;
86 int err = -EINVAL;
87
88 if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
89 struct ip_beet_phdr *ph;
90 int phlen;
91
92 if (!pskb_may_pull(skb, sizeof(*ph)))
93 goto out;
94
95 ph = (struct ip_beet_phdr *)skb->data;
96
97 phlen = sizeof(*ph) + ph->padlen;
98 optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
99 if (optlen < 0 || optlen & 3 || optlen > 250)
100 goto out;
101
102 XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr;
103
104 if (!pskb_may_pull(skb, phlen))
105 goto out;
106 __skb_pull(skb, phlen);
107 }
108
109 skb_push(skb, sizeof(*iph));
110 skb_reset_network_header(skb);
111
112 memmove(skb->data - skb->mac_len, skb_mac_header(skb),
113 skb->mac_len);
114 skb_set_mac_header(skb, -skb->mac_len);
115
116 xfrm4_beet_make_header(skb);
117
118 iph = ip_hdr(skb);
119
120 iph->ihl += optlen / 4;
121 iph->tot_len = htons(skb->len);
122 iph->daddr = x->sel.daddr.a4;
123 iph->saddr = x->sel.saddr.a4;
124 iph->check = 0;
125 iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
126 err = 0;
127 out:
128 return err;
129 }
130
131 static struct xfrm_mode xfrm4_beet_mode = {
132 .input2 = xfrm4_beet_input,
133 .input = xfrm_prepare_input,
134 .output2 = xfrm4_beet_output,
135 .output = xfrm4_prepare_output,
136 .owner = THIS_MODULE,
137 .encap = XFRM_MODE_BEET,
138 .flags = XFRM_MODE_FLAG_TUNNEL,
139 };
140
141 static int __init xfrm4_beet_init(void)
142 {
143 return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
144 }
145
146 static void __exit xfrm4_beet_exit(void)
147 {
148 int err;
149
150 err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
151 BUG_ON(err);
152 }
153
154 module_init(xfrm4_beet_init);
155 module_exit(xfrm4_beet_exit);
156 MODULE_LICENSE("GPL");
157 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);
158
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