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, 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  */
  46 static 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 = skb->nh.ipv6h;
  54
  55         hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
  56         skb->nh.raw = prevhdr - x->props.header_len;
  57         skb->h.raw = skb->data + hdr_len;
  58         memmove(skb->data, iph, hdr_len);
  59         return 0;
  60 }
  61
  62 /*
  63  * Do nothing about routing optimization header unlike IPsec.
  64  */
  65 static int xfrm6_ro_input(struct xfrm_state *x, struct sk_buff *skb)
  66 {
  67         return 0;
  68 }
  69
  70 static struct xfrm_mode xfrm6_ro_mode = {
  71         .input = xfrm6_ro_input,
  72         .output = xfrm6_ro_output,
  73         .owner = THIS_MODULE,
  74         .encap = XFRM_MODE_ROUTEOPTIMIZATION,
  75 };
  76
  77 static int __init xfrm6_ro_init(void)
  78 {
  79         return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6);
  80 }
  81
  82 static void __exit xfrm6_ro_exit(void)
  83 {
  84         int err;
  85
  86         err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6);
  87         BUG_ON(err);
  88 }
  89
  90 module_init(xfrm6_ro_init);
  91 module_exit(xfrm6_ro_exit);
  92 MODULE_LICENSE("GPL");
  93 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION);