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 static void xfrm6_beet_make_header(struct sk_buff *skb)
  23 {
  24         struct ipv6hdr *iph = ipv6_hdr(skb);
  25
  26         iph->version = 6;
  27
  28         memcpy(iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
  29                sizeof(iph->flow_lbl));
  30         iph->nexthdr = XFRM_MODE_SKB_CB(skb)->protocol;
  31
  32         ipv6_change_dsfield(iph, 0, XFRM_MODE_SKB_CB(skb)->tos);
  33         iph->hop_limit = XFRM_MODE_SKB_CB(skb)->ttl;
  34 }
  35
  36 /* Add encapsulation header.
  37  *
  38  * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
  39  */
  40 static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
  41 {
  42         struct ipv6hdr *top_iph;
  43
  44         skb_set_network_header(skb, -x->props.header_len);
  45         skb->mac_header = skb->network_header +
  46                           offsetof(struct ipv6hdr, nexthdr);
  47         skb->transport_header = skb->network_header + sizeof(*top_iph);
  48
  49         xfrm6_beet_make_header(skb);
  50
  51         top_iph = ipv6_hdr(skb);
  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         return 0;
  56 }
  57
  58 static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
  59 {
  60         struct ipv6hdr *ip6h;
  61         const unsigned char *old_mac;
  62         int size = sizeof(struct ipv6hdr);
  63         int err;
  64
  65         err = skb_cow_head(skb, size + skb->mac_len);
  66         if (err)
  67                 goto out;
  68
  69         __skb_push(skb, size);
  70         skb_reset_network_header(skb);
  71
  72         old_mac = skb_mac_header(skb);
  73         skb_set_mac_header(skb, -skb->mac_len);
  74         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
  75
  76         xfrm6_beet_make_header(skb);
  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         .input2 = xfrm6_beet_input,
  89         .input = xfrm_prepare_input,
  90         .output2 = xfrm6_beet_output,
  91         .output = xfrm6_prepare_output,
  92         .owner = THIS_MODULE,
  93         .encap = XFRM_MODE_BEET,
  94         .flags = XFRM_MODE_FLAG_TUNNEL,
  95 };
  96
  97 static int __init xfrm6_beet_init(void)
  98 {
  99         return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
 100 }
 101
 102 static void __exit xfrm6_beet_exit(void)
 103 {
 104         int err;
 105
 106         err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
 107         BUG_ON(err);
 108 }
 109
 110 module_init(xfrm6_beet_init);
 111 module_exit(xfrm6_beet_exit);
 112 MODULE_LICENSE("GPL");
 113 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);