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 = skb->nh.ipv6h;
  22         struct ipv6hdr *inner_iph = skb->h.ipv6h;
  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.  The following fields
  31  * in it shall be filled in by x->type->output:
  32  *      payload_len
  33  *
  34  * On exit, skb->h will be set to the start of the encapsulation header to be
  35  * filled in by x->type->output and skb->nh will be set to the nextheader field
  36  * of the extension header directly preceding the encapsulation header, or in
  37  * its absence, that of the top IP header.  The value of skb->data will always
  38  * point to the top IP header.
  39  */
  40 static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
  41 {
  42         struct dst_entry *dst = skb->dst;
  43         struct ipv6hdr *iph, *top_iph;
  44         int dsfield;
  45
  46         skb_push(skb, x->props.header_len);
  47         iph = skb->nh.ipv6h;
  48
  49         skb->nh.raw = skb->data;
  50         top_iph = skb->nh.ipv6h;
  51         skb->nh.raw = &top_iph->nexthdr;
  52         skb->h.ipv6h = top_iph + 1;
  53
  54         top_iph->version = 6;
  55         top_iph->priority = iph->priority;
  56         top_iph->flow_lbl[0] = iph->flow_lbl[0];
  57         top_iph->flow_lbl[1] = iph->flow_lbl[1];
  58         top_iph->flow_lbl[2] = iph->flow_lbl[2];
  59         dsfield = ipv6_get_dsfield(top_iph);
  60         dsfield = INET_ECN_encapsulate(dsfield, dsfield);
  61         if (x->props.flags & XFRM_STATE_NOECN)
  62                 dsfield &= ~INET_ECN_MASK;
  63         ipv6_change_dsfield(top_iph, 0, dsfield);
  64         top_iph->nexthdr = IPPROTO_IPV6;
  65         top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
  66         ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
  67         ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
  68         return 0;
  69 }
  70
  71 static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
  72 {
  73         int err = -EINVAL;
  74
  75         if (skb->nh.raw[IP6CB(skb)->nhoff] != IPPROTO_IPV6)
  76                 goto out;
  77         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  78                 goto out;
  79
  80         if (skb_cloned(skb) &&
  81             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
  82                 goto out;
  83
  84         if (x->props.flags & XFRM_STATE_DECAP_DSCP)
  85                 ipv6_copy_dscp(skb->nh.ipv6h, skb->h.ipv6h);
  86         if (!(x->props.flags & XFRM_STATE_NOECN))
  87                 ipip6_ecn_decapsulate(skb);
  88         skb->mac.raw = memmove(skb->data - skb->mac_len,
  89                                skb->mac.raw, skb->mac_len);
  90         skb->nh.raw = skb->data;
  91         err = 0;
  92
  93 out:
  94         return err;
  95 }
  96
  97 static struct xfrm_mode xfrm6_tunnel_mode = {
  98         .input = xfrm6_tunnel_input,
  99         .output = xfrm6_tunnel_output,
 100         .owner = THIS_MODULE,
 101         .encap = XFRM_MODE_TUNNEL,
 102 };
 103
 104 static int __init xfrm6_tunnel_init(void)
 105 {
 106         return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
 107 }
 108
 109 static void __exit xfrm6_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_tunnel_init);
 118 module_exit(xfrm6_tunnel_exit);
 119 MODULE_LICENSE("GPL");
 120 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);