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