xfrm6_mode_ro.c revision 45b17f48eaf5e5ff4202454985557b3240141caa 
1/*
2 * xfrm6_mode_ro.c - Route optimization mode for IPv6.
3 *
4 * Copyright (C)2003-2006 Helsinki University of Technology
5 * Copyright (C)2003-2006 USAGI/WIDE Project
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20 */
21/*
22 * Authors:
23 *	Noriaki TAKAMIYA @USAGI
24 *	Masahide NAKAMURA @USAGI
25 */
26
27#include <linux/init.h>
28#include <linux/kernel.h>
29#include <linux/module.h>
30#include <linux/skbuff.h>
31#include <linux/stringify.h>
32#include <linux/time.h>
33#include <net/ipv6.h>
34#include <net/xfrm.h>
35
36/* Add route optimization header space.
37 *
38 * The IP header and mutable extension headers will be moved forward to make
39 * space for the route optimization header.
40 *
41 * On exit, skb->h will be set to the start of the encapsulation header to be
42 * filled in by x->type->output and skb->nh will be set to the nextheader field
43 * of the extension header directly preceding the encapsulation header, or in
44 * its absence, that of the top IP header.  The value of skb->data will always
45 * point to the top IP header.
46 */
47static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
48{
49	struct ipv6hdr *iph;
50	u8 *prevhdr;
51	int hdr_len;
52
53	skb_push(skb, x->props.header_len);
54	iph = ipv6_hdr(skb);
55
56	hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
57	skb_set_network_header(skb,
58			       (prevhdr - x->props.header_len) - skb->data);
59	skb_set_transport_header(skb, hdr_len);
60	memmove(skb->data, iph, hdr_len);
61
62	x->lastused = get_seconds();
63
64	return 0;
65}
66
67/*
68 * Do nothing about routing optimization header unlike IPsec.
69 */
70static int xfrm6_ro_input(struct xfrm_state *x, struct sk_buff *skb)
71{
72	return 0;
73}
74
75static struct xfrm_mode xfrm6_ro_mode = {
76	.input = xfrm6_ro_input,
77	.output = xfrm6_ro_output,
78	.owner = THIS_MODULE,
79	.encap = XFRM_MODE_ROUTEOPTIMIZATION,
80};
81
82static int __init xfrm6_ro_init(void)
83{
84	return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6);
85}
86
87static void __exit xfrm6_ro_exit(void)
88{
89	int err;
90
91	err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6);
92	BUG_ON(err);
93}
94
95module_init(xfrm6_ro_init);
96module_exit(xfrm6_ro_exit);
97MODULE_LICENSE("GPL");
98MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION);
99