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         struct ip_beet_phdr *ph;
  44         int optlen, hdr_len;
  45
  46         hdr_len = 0;
  47         optlen = XFRM_MODE_SKB_CB(skb)->optlen;
  48         if (unlikely(optlen))
  49                 hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
  50
  51         skb_set_network_header(skb, -x->props.header_len - hdr_len);
  52         if (x->sel.family != AF_INET6)
  53                 skb->network_header += IPV4_BEET_PHMAXLEN;
  54         skb->mac_header = skb->network_header +
  55                           offsetof(struct ipv6hdr, nexthdr);
  56         skb->transport_header = skb->network_header + sizeof(*top_iph);
  57         ph = (struct ip_beet_phdr *)__skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl-hdr_len);
  58
  59         xfrm6_beet_make_header(skb);
  60
  61         top_iph = ipv6_hdr(skb);
  62         if (unlikely(optlen)) {
  63
  64                 BUG_ON(optlen < 0);
  65
  66                 ph->padlen = 4 - (optlen & 4);
  67                 ph->hdrlen = optlen / 8;
  68                 ph->nexthdr = top_iph->nexthdr;
  69                 if (ph->padlen)
  70                         memset(ph + 1, IPOPT_NOP, ph->padlen);
  71
  72                 top_iph->nexthdr = IPPROTO_BEETPH;
  73         }
  74
  75         ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
  76         ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
  77         return 0;
  78 }
  79
  80 static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
  81 {
  82         struct ipv6hdr *ip6h;
  83         const unsigned char *old_mac;
  84         int size = sizeof(struct ipv6hdr);
  85         int err;
  86
  87         err = skb_cow_head(skb, size + skb->mac_len);
  88         if (err)
  89                 goto out;
  90
  91         __skb_push(skb, size);
  92         skb_reset_network_header(skb);
  93
  94         old_mac = skb_mac_header(skb);
  95         skb_set_mac_header(skb, -skb->mac_len);
  96         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
  97
  98         xfrm6_beet_make_header(skb);
  99
 100         ip6h = ipv6_hdr(skb);
 101         ip6h->payload_len = htons(skb->len - size);
 102         ipv6_addr_copy(&ip6h->daddr, (struct in6_addr *) &x->sel.daddr.a6);
 103         ipv6_addr_copy(&ip6h->saddr, (struct in6_addr *) &x->sel.saddr.a6);
 104         err = 0;
 105 out:
 106         return err;
 107 }
 108
 109 static struct xfrm_mode xfrm6_beet_mode = {
 110         .input2 = xfrm6_beet_input,
 111         .input = xfrm_prepare_input,
 112         .output2 = xfrm6_beet_output,
 113         .output = xfrm6_prepare_output,
 114         .owner = THIS_MODULE,
 115         .encap = XFRM_MODE_BEET,
 116         .flags = XFRM_MODE_FLAG_TUNNEL,
 117 };
 118
 119 static int __init xfrm6_beet_init(void)
 120 {
 121         return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
 122 }
 123
 124 static void __exit xfrm6_beet_exit(void)
 125 {
 126         int err;
 127
 128         err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
 129         BUG_ON(err);
 130 }
 131
 132 module_init(xfrm6_beet_init);
 133 module_exit(xfrm6_beet_exit);
 134 MODULE_LICENSE("GPL");
 135 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);