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         struct iphdr *iphv4;
  45         int optlen, hdr_len;
  46
  47         iphv4 = ip_hdr(skb);
  48         hdr_len = 0;
  49         optlen = XFRM_MODE_SKB_CB(skb)->optlen;
  50         if (unlikely(optlen))
  51                 hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);
  52
  53         skb_set_network_header(skb, -x->props.header_len - hdr_len);
  54         if (x->sel.family != AF_INET6)
  55                 skb->network_header += IPV4_BEET_PHMAXLEN;
  56         skb->mac_header = skb->network_header +
  57                           offsetof(struct ipv6hdr, nexthdr);
  58         skb->transport_header = skb->network_header + sizeof(*top_iph);
  59         ph = (struct ip_beet_phdr *)__skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl-hdr_len);
  60
  61         xfrm6_beet_make_header(skb);
  62
  63         top_iph = ipv6_hdr(skb);
  64         if (unlikely(optlen)) {
  65
  66                 BUG_ON(optlen < 0);
  67
  68                 ph->padlen = 4 - (optlen & 4);
  69                 ph->hdrlen = optlen / 8;
  70                 ph->nexthdr = top_iph->nexthdr;
  71                 if (ph->padlen)
  72                         memset(ph + 1, IPOPT_NOP, ph->padlen);
  73
  74                 top_iph->nexthdr = IPPROTO_BEETPH;
  75         }
  76
  77         ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
  78         ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
  79         return 0;
  80 }
  81
  82 static int xfrm6_beet_input(struct xfrm_state *x, struct sk_buff *skb)
  83 {
  84         struct ipv6hdr *ip6h;
  85         const unsigned char *old_mac;
  86         int size = sizeof(struct ipv6hdr);
  87         int err;
  88
  89         err = skb_cow_head(skb, size + skb->mac_len);
  90         if (err)
  91                 goto out;
  92
  93         __skb_push(skb, size);
  94         skb_reset_network_header(skb);
  95
  96         old_mac = skb_mac_header(skb);
  97         skb_set_mac_header(skb, -skb->mac_len);
  98         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
  99
 100         xfrm6_beet_make_header(skb);
 101
 102         ip6h = ipv6_hdr(skb);
 103         ip6h->payload_len = htons(skb->len - size);
 104         ipv6_addr_copy(&ip6h->daddr, (struct in6_addr *) &x->sel.daddr.a6);
 105         ipv6_addr_copy(&ip6h->saddr, (struct in6_addr *) &x->sel.saddr.a6);
 106         err = 0;
 107 out:
 108         return err;
 109 }
 110
 111 static struct xfrm_mode xfrm6_beet_mode = {
 112         .input2 = xfrm6_beet_input,
 113         .input = xfrm_prepare_input,
 114         .output2 = xfrm6_beet_output,
 115         .output = xfrm6_prepare_output,
 116         .owner = THIS_MODULE,
 117         .encap = XFRM_MODE_BEET,
 118         .flags = XFRM_MODE_FLAG_TUNNEL,
 119 };
 120
 121 static int __init xfrm6_beet_init(void)
 122 {
 123         return xfrm_register_mode(&xfrm6_beet_mode, AF_INET6);
 124 }
 125
 126 static void __exit xfrm6_beet_exit(void)
 127 {
 128         int err;
 129
 130         err = xfrm_unregister_mode(&xfrm6_beet_mode, AF_INET6);
 131         BUG_ON(err);
 132 }
 133
 134 module_init(xfrm6_beet_init);
 135 module_exit(xfrm6_beet_exit);
 136 MODULE_LICENSE("GPL");
 137 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_BEET);