net/ipv6/xfrm6_mode_tunnel.c

   1 /*
   2  * xfrm6_mode_tunnel.c - Tunnel mode encapsulation for IPv6.
   3  *
   4  * Copyright (C) 2002 USAGI/WIDE Project
   5  * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
   6  */
   7
   8 #include <linux/gfp.h>
   9 #include <linux/init.h>
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/stringify.h>
  14 #include <net/dsfield.h>
  15 #include <net/dst.h>
  16 #include <net/inet_ecn.h>
  17 #include <net/ip6_route.h>
  18 #include <net/ipv6.h>
  19 #include <net/xfrm.h>
  20
  21 static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
  22 {
  23         const struct ipv6hdr *outer_iph = ipv6_hdr(skb);
  24         struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
  25
  26         if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
  27                 IP6_ECN_set_ce(inner_iph);
  28 }
  29
  30 /* Add encapsulation header.
  31  *
  32  * The top IP header will be constructed per RFC 2401.
  33  */
  34 static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
  35 {
  36         struct dst_entry *dst = skb_dst(skb);
  37         struct ipv6hdr *top_iph;
  38         int dsfield;
  39
  40         skb_set_network_header(skb, -x->props.header_len);
  41         skb->mac_header = skb->network_header +
  42                           offsetof(struct ipv6hdr, nexthdr);
  43         skb->transport_header = skb->network_header + sizeof(*top_iph);
  44         top_iph = ipv6_hdr(skb);
  45
  46         top_iph->version = 6;
  47
  48         memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
  49                sizeof(top_iph->flow_lbl));
  50         top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
  51
  52         dsfield = XFRM_MODE_SKB_CB(skb)->tos;
  53         dsfield = INET_ECN_encapsulate(dsfield, dsfield);
  54         if (x->props.flags & XFRM_STATE_NOECN)
  55                 dsfield &= ~INET_ECN_MASK;
  56         ipv6_change_dsfield(top_iph, 0, dsfield);
  57         top_iph->hop_limit = ip6_dst_hoplimit(dst->child);
  58         top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
  59         top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
  60         return 0;
  61 }
  62
  63 static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
  64 {
  65         int err = -EINVAL;
  66         const unsigned char *old_mac;
  67
  68         if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
  69                 goto out;
  70         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  71                 goto out;
  72
  73         if (skb_cloned(skb) &&
  74             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
  75                 goto out;
  76
  77         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
  78                 ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
  79                                ipipv6_hdr(skb));
  80         if (!(x->props.flags & XFRM_STATE_NOECN))
  81                 ipip6_ecn_decapsulate(skb);
  82
  83         old_mac = skb_mac_header(skb);
  84         skb_set_mac_header(skb, -skb->mac_len);
  85         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
  86         skb_reset_network_header(skb);
  87         err = 0;
  88
  89 out:
  90         return err;
  91 }
  92
  93 static struct xfrm_mode xfrm6_tunnel_mode = {
  94         .input2 = xfrm6_mode_tunnel_input,
  95         .input = xfrm_prepare_input,
  96         .output2 = xfrm6_mode_tunnel_output,
  97         .output = xfrm6_prepare_output,
  98         .owner = THIS_MODULE,
  99         .encap = XFRM_MODE_TUNNEL,
 100         .flags = XFRM_MODE_FLAG_TUNNEL,
 101 };
 102
 103 static int __init xfrm6_mode_tunnel_init(void)
 104 {
 105         return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
 106 }
 107
 108 static void __exit xfrm6_mode_tunnel_exit(void)
 109 {
 110         int err;
 111
 112         err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
 113         BUG_ON(err);
 114 }
 115
 116 module_init(xfrm6_mode_tunnel_init);
 117 module_exit(xfrm6_mode_tunnel_exit);
 118 MODULE_LICENSE("GPL");
 119 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);