1/*
2 * xfrm6_mode_beet.c - BEET mode encapsulation for IPv6.
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/dsfield.h>
17#include <net/dst.h>
18#include <net/inet_ecn.h>
19#include <net/ipv6.h>
20#include <net/xfrm.h>
21
22/* Add encapsulation header.
23 *
24 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
25 * The following fields in it shall be filled in by x->type->output:
26 *	payload_len
27 *
28 * On exit, skb->h will be set to the start of the encapsulation header to be
29 * filled in by x->type->output and skb->nh will be set to the nextheader field
30 * of the extension header directly preceding the encapsulation header, or in
31 * its absence, that of the top IP header.  The value of skb->data will always
32 * point to the top IP header.
33 */
34static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
35{
36	struct ipv6hdr *iph, *top_iph;
37	u8 *prevhdr;
38	int hdr_len;
39
40	skb_push(skb, x->props.header_len);
41	iph = ipv6_hdr(skb);
42
43	hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
44	skb_set_network_header(skb,
45			       (prevhdr - x->props.header_len) - skb->data);
46	skb_set_transport_header(skb, hdr_len);
47	memmove(skb->data, iph, hdr_len);
48
49	skb_reset_network_header(skb);
50	top_iph = ipv6_hdr(skb);
51	skb->transport_header = skb->network_header + sizeof(struct ipv6hdr);
52	skb->network_header += offsetof(struct ipv6hdr, nexthdr);
53
54	ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
55	ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
56
57	return 0;
58}
59
60static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
61{
62	struct ipv6hdr *ip6h;
63	const unsigned char *old_mac;
64	int size = sizeof(struct ipv6hdr);
65	int err = -EINVAL;
66
67	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
68		goto out;
69
70	skb_push(skb, size);
71	memmove(skb->data, skb_network_header(skb), size);
72	skb_reset_network_header(skb);
73
74	old_mac = skb_mac_header(skb);
75	skb_set_mac_header(skb, -skb->mac_len);
76	memmove(skb_mac_header(skb), old_mac, skb->mac_len);
77
78	ip6h = ipv6_hdr(skb);
79	ip6h->payload_len = htons(skb->len - size);
80	ipv6_addr_copy(&ip6h->daddr, (struct in6_addr *) &x->sel.daddr.a6);
81	ipv6_addr_copy(&ip6h->saddr, (struct in6_addr *) &x->sel.saddr.a6);
82	err = 0;
83out:
84	return err;
85}
86
87static struct xfrm_mode xfrm6_beet_mode = {
88	.input = xfrm6_beet_input,
89	.output = xfrm6_beet_output,
90	.owner = THIS_MODULE,
91	.encap = XFRM_MODE_BEET,
92};
93
94static int __init xfrm6_beet_init(void)
95{
96	return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
97}
98
99static void __exit xfrm6_beet_exit(void)
100{
101	int err;
102
103	err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
104	BUG_ON(err);
105}
106
107module_init(xfrm6_beet_init);
108module_exit(xfrm6_beet_exit);
109MODULE_LICENSE("GPL");
110MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);
111