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/init.h>
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/stringify.h>
  13 #include <net/dsfield.h>
  14 #include <net/dst.h>
  15 #include <net/inet_ecn.h>
  16 #include <net/ipv6.h>
  17 #include <net/xfrm.h>
  18
  19 static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
  20 {
  21         struct ipv6hdr *outer_iph = ipv6_hdr(skb);
  22         struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
  23
  24         if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
  25                 IP6_ECN_set_ce(inner_iph);
  26 }
  27
  28 /* Add encapsulation header.
  29  *
  30  * The top IP header will be constructed per RFC 2401.
  31  */
  32 static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
  33 {
  34         struct dst_entry *dst = skb_dst(skb);
  35         struct ipv6hdr *top_iph;
  36         int dsfield;
  37
  38         skb_set_network_header(skb, -x->props.header_len);
  39         skb->mac_header = skb->network_header +
  40                           offsetof(struct ipv6hdr, nexthdr);
  41         skb->transport_header = skb->network_header + sizeof(*top_iph);
  42         top_iph = ipv6_hdr(skb);
  43
  44         top_iph->version = 6;
  45
  46         memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
  47                sizeof(top_iph->flow_lbl));
  48         top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
  49
  50         dsfield = XFRM_MODE_SKB_CB(skb)->tos;
  51         dsfield = INET_ECN_encapsulate(dsfield, dsfield);
  52         if (x->props.flags & XFRM_STATE_NOECN)
  53                 dsfield &= ~INET_ECN_MASK;
  54         ipv6_change_dsfield(top_iph, 0, dsfield);
  55         top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
  56         ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
  57         ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
  58         return 0;
  59 }
  60
  61 static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
  62 {
  63         int err = -EINVAL;
  64         const unsigned char *old_mac;
  65
  66         if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
  67                 goto out;
  68         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  69                 goto out;
  70
  71         if (skb_cloned(skb) &&
  72             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
  73                 goto out;
  74
  75         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
  76                 ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
  77                                ipipv6_hdr(skb));
  78         if (!(x->props.flags & XFRM_STATE_NOECN))
  79                 ipip6_ecn_decapsulate(skb);
  80
  81         old_mac = skb_mac_header(skb);
  82         skb_set_mac_header(skb, -skb->mac_len);
  83         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
  84         skb_reset_network_header(skb);
  85         err = 0;
  86
  87 out:
  88         return err;
  89 }
  90
  91 static struct xfrm_mode xfrm6_tunnel_mode = {
  92         .input2 = xfrm6_mode_tunnel_input,
  93         .input = xfrm_prepare_input,
  94         .output2 = xfrm6_mode_tunnel_output,
  95         .output = xfrm6_prepare_output,
  96         .owner = THIS_MODULE,
  97         .encap = XFRM_MODE_TUNNEL,
  98         .flags = XFRM_MODE_FLAG_TUNNEL,
  99 };
 100
 101 static int __init xfrm6_mode_tunnel_init(void)
 102 {
 103         return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
 104 }
 105
 106 static void __exit xfrm6_mode_tunnel_exit(void)
 107 {
 108         int err;
 109
 110         err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
 111         BUG_ON(err);
 112 }
 113
 114 module_init(xfrm6_mode_tunnel_init);
 115 module_exit(xfrm6_mode_tunnel_exit);
 116 MODULE_LICENSE("GPL");
 117 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);