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         if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
  53                 dsfield = 0;
  54         else
  55                 dsfield = XFRM_MODE_SKB_CB(skb)->tos;
  56         dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
  57         if (x->props.flags & XFRM_STATE_NOECN)
  58                 dsfield &= ~INET_ECN_MASK;
  59         ipv6_change_dsfield(top_iph, 0, dsfield);
  60         top_iph->hop_limit = ip6_dst_hoplimit(dst->child);
  61         top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
  62         top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
  63         return 0;
  64 }
  65
  66 static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
  67 {
  68         int err = -EINVAL;
  69
  70         if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
  71                 goto out;
  72         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  73                 goto out;
  74
  75         err = skb_unclone(skb, GFP_ATOMIC);
  76         if (err)
  77                 goto out;
  78
  79         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
  80                 ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
  81                                ipipv6_hdr(skb));
  82         if (!(x->props.flags & XFRM_STATE_NOECN))
  83                 ipip6_ecn_decapsulate(skb);
  84
  85         skb_reset_network_header(skb);
  86         skb_mac_header_rebuild(skb);
  87
  88         err = 0;
  89
  90 out:
  91         return err;
  92 }
  93
  94 static struct xfrm_mode xfrm6_tunnel_mode = {
  95         .input2 = xfrm6_mode_tunnel_input,
  96         .input = xfrm_prepare_input,
  97         .output2 = xfrm6_mode_tunnel_output,
  98         .output = xfrm6_prepare_output,
  99         .owner = THIS_MODULE,
 100         .encap = XFRM_MODE_TUNNEL,
 101         .flags = XFRM_MODE_FLAG_TUNNEL,
 102 };
 103
 104 static int __init xfrm6_mode_tunnel_init(void)
 105 {
 106         return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
 107 }
 108
 109 static void __exit xfrm6_mode_tunnel_exit(void)
 110 {
 111         int err;
 112
 113         err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
 114         BUG_ON(err);
 115 }
 116
 117 module_init(xfrm6_mode_tunnel_init);
 118 module_exit(xfrm6_mode_tunnel_exit);
 119 MODULE_LICENSE("GPL");
 120 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);