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
xfrm4_beet_make_header(struct sk_buff * skb)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 */
xfrm4_beet_output(struct xfrm_state * x,struct sk_buff * skb)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, -x->props.header_len -
51 hdrlen + (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
52 if (x->sel.family != AF_INET6)
53 skb->network_header += IPV4_BEET_PHMAXLEN;
54 skb->mac_header = skb->network_header +
55 offsetof(struct iphdr, protocol);
56 skb->transport_header = skb->network_header + sizeof(*top_iph);
57
58 xfrm4_beet_make_header(skb);
59
60 ph = (struct ip_beet_phdr *)
61 __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);
62
63 top_iph = ip_hdr(skb);
64
65 if (unlikely(optlen)) {
66 BUG_ON(optlen < 0);
67
68 ph->padlen = 4 - (optlen & 4);
69 ph->hdrlen = optlen / 8;
70 ph->nexthdr = top_iph->protocol;
71 if (ph->padlen)
72 memset(ph + 1, IPOPT_NOP, ph->padlen);
73
74 top_iph->protocol = IPPROTO_BEETPH;
75 top_iph->ihl = sizeof(struct iphdr) / 4;
76 }
77
78 top_iph->saddr = x->props.saddr.a4;
79 top_iph->daddr = x->id.daddr.a4;
80
81 return 0;
82 }
83
xfrm4_beet_input(struct xfrm_state * x,struct sk_buff * skb)84 static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
85 {
86 struct iphdr *iph;
87 int optlen = 0;
88 int err = -EINVAL;
89
90 if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
91 struct ip_beet_phdr *ph;
92 int phlen;
93
94 if (!pskb_may_pull(skb, sizeof(*ph)))
95 goto out;
96
97 ph = (struct ip_beet_phdr *)skb->data;
98
99 phlen = sizeof(*ph) + ph->padlen;
100 optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
101 if (optlen < 0 || optlen & 3 || optlen > 250)
102 goto out;
103
104 XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr;
105
106 if (!pskb_may_pull(skb, phlen))
107 goto out;
108 __skb_pull(skb, phlen);
109 }
110
111 skb_push(skb, sizeof(*iph));
112 skb_reset_network_header(skb);
113 skb_mac_header_rebuild(skb);
114
115 xfrm4_beet_make_header(skb);
116
117 iph = ip_hdr(skb);
118
119 iph->ihl += optlen / 4;
120 iph->tot_len = htons(skb->len);
121 iph->daddr = x->sel.daddr.a4;
122 iph->saddr = x->sel.saddr.a4;
123 iph->check = 0;
124 iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
125 err = 0;
126 out:
127 return err;
128 }
129
130 static struct xfrm_mode xfrm4_beet_mode = {
131 .input2 = xfrm4_beet_input,
132 .input = xfrm_prepare_input,
133 .output2 = xfrm4_beet_output,
134 .output = xfrm4_prepare_output,
135 .owner = THIS_MODULE,
136 .encap = XFRM_MODE_BEET,
137 .flags = XFRM_MODE_FLAG_TUNNEL,
138 };
139
xfrm4_beet_init(void)140 static int __init xfrm4_beet_init(void)
141 {
142 return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
143 }
144
xfrm4_beet_exit(void)145 static void __exit xfrm4_beet_exit(void)
146 {
147 int err;
148
149 err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
150 BUG_ON(err);
151 }
152
153 module_init(xfrm4_beet_init);
154 module_exit(xfrm4_beet_exit);
155 MODULE_LICENSE("GPL");
156 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);
157