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 <net/ipv6.h> 33#include <net/xfrm.h> 34 35/* Add route optimization header space. 36 * 37 * The IP header and mutable extension headers will be moved forward to make 38 * space for the route optimization header. 39 * 40 * On exit, skb->h will be set to the start of the encapsulation header to be 41 * filled in by x->type->output and skb->nh will be set to the nextheader field 42 * of the extension header directly preceding the encapsulation header, or in 43 * its absence, that of the top IP header. The value of skb->data will always 44 * point to the top IP header. 45 */ 46static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb) 47{ 48 struct ipv6hdr *iph; 49 u8 *prevhdr; 50 int hdr_len; 51 52 skb_push(skb, x->props.header_len); 53 iph = ipv6_hdr(skb); 54 55 hdr_len = x->type->hdr_offset(x, skb, &prevhdr); 56 skb_set_network_header(skb, 57 (prevhdr - x->props.header_len) - skb->data); 58 skb_set_transport_header(skb, hdr_len); 59 memmove(skb->data, iph, hdr_len); 60 return 0; 61} 62 63/* 64 * Do nothing about routing optimization header unlike IPsec. 65 */ 66static int xfrm6_ro_input(struct xfrm_state *x, struct sk_buff *skb) 67{ 68 return 0; 69} 70 71static struct xfrm_mode xfrm6_ro_mode = { 72 .input = xfrm6_ro_input, 73 .output = xfrm6_ro_output, 74 .owner = THIS_MODULE, 75 .encap = XFRM_MODE_ROUTEOPTIMIZATION, 76}; 77 78static int __init xfrm6_ro_init(void) 79{ 80 return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6); 81} 82 83static void __exit xfrm6_ro_exit(void) 84{ 85 int err; 86 87 err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6); 88 BUG_ON(err); 89} 90 91module_init(xfrm6_ro_init); 92module_exit(xfrm6_ro_exit); 93MODULE_LICENSE("GPL"); 94MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION); 95