net/ipv6/xfrm6_mode_ro.c

   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, see <http://www.gnu.org/licenses/>.
  19  */
  20 /*
  21  * Authors:
  22  *      Noriaki TAKAMIYA @USAGI
  23  *      Masahide NAKAMURA @USAGI
  24  */
  25
  26 #include <linux/init.h>
  27 #include <linux/kernel.h>
  28 #include <linux/module.h>
  29 #include <linux/skbuff.h>
  30 #include <linux/spinlock.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 static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
  42 {
  43         struct ipv6hdr *iph;
  44         u8 *prevhdr;
  45         int hdr_len;
  46
  47         iph = ipv6_hdr(skb);
  48
  49         hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
  50         if (hdr_len < 0)
  51                 return hdr_len;
  52         skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
  53         skb_set_network_header(skb, -x->props.header_len);
  54         skb->transport_header = skb->network_header + hdr_len;
  55         __skb_pull(skb, hdr_len);
  56         memmove(ipv6_hdr(skb), iph, hdr_len);
  57
  58         x->lastused = get_seconds();
  59
  60         return 0;
  61 }
  62
  63 static struct xfrm_mode xfrm6_ro_mode = {
  64         .output = xfrm6_ro_output,
  65         .owner = THIS_MODULE,
  66         .encap = XFRM_MODE_ROUTEOPTIMIZATION,
  67 };
  68
  69 static int __init xfrm6_ro_init(void)
  70 {
  71         return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6);
  72 }
  73
  74 static void __exit xfrm6_ro_exit(void)
  75 {
  76         int err;
  77
  78         err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6);
  79         BUG_ON(err);
  80 }
  81
  82 module_init(xfrm6_ro_init);
  83 module_exit(xfrm6_ro_exit);
  84 MODULE_LICENSE("GPL");
  85 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION);