net/ipv6/xfrm6_mode_beet.c

   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 the mac header will be set to the
  30  * nextheader field of the extension header directly preceding the
  31  * encapsulation header, or in its absence, that of the top IP header.
  32  * The value of the network header will always point to the top IP header
  33  * while skb->data will point to the payload.
  34  */
  35 static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
  36 {
  37         struct ipv6hdr *iph, *top_iph;
  38         u8 *prevhdr;
  39         int hdr_len;
  40
  41         iph = ipv6_hdr(skb);
  42
  43         hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
  44
  45         skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
  46         skb_set_network_header(skb, -x->props.header_len);
  47         skb_set_transport_header(skb, hdr_len - x->props.header_len);
  48         __skb_pull(skb, hdr_len);
  49
  50         top_iph = ipv6_hdr(skb);
  51         memmove(top_iph, iph, hdr_len);
  52
  53         ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
  54         ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
  55
  56         return 0;
  57 }
  58
  59 static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
  60 {
  61         struct ipv6hdr *ip6h;
  62         const unsigned char *old_mac;
  63         int size = sizeof(struct ipv6hdr);
  64         int err = -EINVAL;
  65
  66         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  67                 goto out;
  68
  69         skb_push(skb, size);
  70         memmove(skb->data, skb_network_header(skb), size);
  71         skb_reset_network_header(skb);
  72
  73         old_mac = skb_mac_header(skb);
  74         skb_set_mac_header(skb, -skb->mac_len);
  75         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
  76
  77         ip6h = ipv6_hdr(skb);
  78         ip6h->payload_len = htons(skb->len - size);
  79         ipv6_addr_copy(&ip6h->daddr, (struct in6_addr *) &x->sel.daddr.a6);
  80         ipv6_addr_copy(&ip6h->saddr, (struct in6_addr *) &x->sel.saddr.a6);
  81         err = 0;
  82 out:
  83         return err;
  84 }
  85
  86 static struct xfrm_mode xfrm6_beet_mode = {
  87         .input = xfrm6_beet_input,
  88         .output = xfrm6_beet_output,
  89         .owner = THIS_MODULE,
  90         .encap = XFRM_MODE_BEET,
  91 };
  92
  93 static int __init xfrm6_beet_init(void)
  94 {
  95         return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
  96 }
  97
  98 static void __exit xfrm6_beet_exit(void)
  99 {
 100         int err;
 101
 102         err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
 103         BUG_ON(err);
 104 }
 105
 106 module_init(xfrm6_beet_init);
 107 module_exit(xfrm6_beet_exit);
 108 MODULE_LICENSE("GPL");
 109 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);