2 * xfrm4_mode_beet.c - BEET mode encapsulation for IPv4.
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>
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>
20 /* Add encapsulation header.
22 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
23 * The following fields in it shall be filled in by x->type->output:
27 static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
29 struct ip_beet_phdr *ph;
30 struct iphdr *iph, *top_iph;
36 optlen = iph->ihl * 4 - sizeof(*iph);
38 hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
40 skb_set_network_header(skb, IPV4_BEET_PHMAXLEN - x->props.header_len -
42 skb->mac_header = skb->network_header +
43 offsetof(struct iphdr, protocol);
44 skb->transport_header = skb->network_header + sizeof(*iph);
46 ph = (struct ip_beet_phdr *)__skb_pull(skb, sizeof(*iph) - hdrlen);
48 top_iph = ip_hdr(skb);
49 memmove(top_iph, iph, sizeof(*iph));
50 if (unlikely(optlen)) {
53 ph->padlen = 4 - (optlen & 4);
54 ph->hdrlen = optlen / 8;
55 ph->nexthdr = top_iph->protocol;
57 memset(ph + 1, IPOPT_NOP, ph->padlen);
59 top_iph->protocol = IPPROTO_BEETPH;
60 top_iph->ihl = sizeof(struct iphdr) / 4;
63 top_iph->saddr = x->props.saddr.a4;
64 top_iph->daddr = x->id.daddr.a4;
69 static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
71 struct iphdr *iph = ip_hdr(skb);
77 if (unlikely(iph->protocol == IPPROTO_BEETPH)) {
78 struct ip_beet_phdr *ph;
80 if (!pskb_may_pull(skb, sizeof(*ph)))
82 ph = (struct ip_beet_phdr *)(ipip_hdr(skb) + 1);
84 phlen = sizeof(*ph) + ph->padlen;
85 optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
86 if (optlen < 0 || optlen & 3 || optlen > 250)
89 if (!pskb_may_pull(skb, phlen + optlen))
91 skb->len -= phlen + optlen;
93 ph_nexthdr = ph->nexthdr;
96 skb_set_network_header(skb, phlen - sizeof(*iph));
97 memmove(skb_network_header(skb), iph, sizeof(*iph));
98 skb_set_transport_header(skb, phlen + optlen);
99 skb->data = skb_transport_header(skb);
102 iph->ihl = (sizeof(*iph) + optlen) / 4;
103 iph->tot_len = htons(skb->len + iph->ihl * 4);
104 iph->daddr = x->sel.daddr.a4;
105 iph->saddr = x->sel.saddr.a4;
107 iph->protocol = ph_nexthdr;
109 iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
115 static struct xfrm_mode xfrm4_beet_mode = {
116 .input = xfrm4_beet_input,
117 .output = xfrm4_beet_output,
118 .owner = THIS_MODULE,
119 .encap = XFRM_MODE_BEET,
122 static int __init xfrm4_beet_init(void)
124 return xfrm_register_mode(&xfrm4_beet_mode, AF_INET);
127 static void __exit xfrm4_beet_exit(void)
131 err = xfrm_unregister_mode(&xfrm4_beet_mode, AF_INET);
135 module_init(xfrm4_beet_init);
136 module_exit(xfrm4_beet_exit);
137 MODULE_LICENSE("GPL");
138 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_BEET);