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 static inline void ip6ip_ecn_decapsulate(struct sk_buff *skb)
  29 {
  30         if (INET_ECN_is_ce(ipv6_get_dsfield(ipv6_hdr(skb))))
  31                         IP_ECN_set_ce(ipip_hdr(skb));
  32 }
  33
  34 /* Add encapsulation header.
  35  *
  36  * The top IP header will be constructed per RFC 2401.
  37  */
  38 static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
  39 {
  40         struct dst_entry *dst = skb->dst;
  41         struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
  42         struct ipv6hdr *iph, *top_iph;
  43         int dsfield;
  44
  45         iph = ipv6_hdr(skb);
  46
  47         skb_set_network_header(skb, -x->props.header_len);
  48         skb->mac_header = skb->network_header +
  49                           offsetof(struct ipv6hdr, nexthdr);
  50         skb->transport_header = skb->network_header + sizeof(*iph);
  51         top_iph = ipv6_hdr(skb);
  52
  53         top_iph->version = 6;
  54         if (xdst->route->ops->family == AF_INET6) {
  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                 top_iph->nexthdr = IPPROTO_IPV6;
  60         } else {
  61                 top_iph->priority = 0;
  62                 top_iph->flow_lbl[0] = 0;
  63                 top_iph->flow_lbl[1] = 0;
  64                 top_iph->flow_lbl[2] = 0;
  65                 top_iph->nexthdr = IPPROTO_IPIP;
  66         }
  67         dsfield = ipv6_get_dsfield(top_iph);
  68         dsfield = INET_ECN_encapsulate(dsfield, dsfield);
  69         if (x->props.flags & XFRM_STATE_NOECN)
  70                 dsfield &= ~INET_ECN_MASK;
  71         ipv6_change_dsfield(top_iph, 0, dsfield);
  72         top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
  73         ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
  74         ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
  75         skb->protocol = htons(ETH_P_IPV6);
  76         return 0;
  77 }
  78
  79 static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
  80 {
  81         int err = -EINVAL;
  82         const unsigned char *old_mac;
  83         const unsigned char *nh = skb_network_header(skb);
  84
  85         if (nh[IP6CB(skb)->nhoff] != IPPROTO_IPV6 &&
  86             nh[IP6CB(skb)->nhoff] != IPPROTO_IPIP)
  87                 goto out;
  88         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  89                 goto out;
  90
  91         if (skb_cloned(skb) &&
  92             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
  93                 goto out;
  94
  95         nh = skb_network_header(skb);
  96         if (nh[IP6CB(skb)->nhoff] == IPPROTO_IPV6) {
  97                 if (x->props.flags & XFRM_STATE_DECAP_DSCP)
  98                         ipv6_copy_dscp(ipv6_hdr(skb), ipipv6_hdr(skb));
  99                 if (!(x->props.flags & XFRM_STATE_NOECN))
 100                         ipip6_ecn_decapsulate(skb);
 101         } else {
 102                 if (!(x->props.flags & XFRM_STATE_NOECN))
 103                         ip6ip_ecn_decapsulate(skb);
 104                 skb->protocol = htons(ETH_P_IP);
 105         }
 106         old_mac = skb_mac_header(skb);
 107         skb_set_mac_header(skb, -skb->mac_len);
 108         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
 109         skb_reset_network_header(skb);
 110         err = 0;
 111
 112 out:
 113         return err;
 114 }
 115
 116 static struct xfrm_mode xfrm6_tunnel_mode = {
 117         .input = xfrm6_tunnel_input,
 118         .output = xfrm6_tunnel_output,
 119         .owner = THIS_MODULE,
 120         .encap = XFRM_MODE_TUNNEL,
 121         .flags = XFRM_MODE_FLAG_TUNNEL,
 122 };
 123
 124 static int __init xfrm6_tunnel_init(void)
 125 {
 126         return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
 127 }
 128
 129 static void __exit xfrm6_tunnel_exit(void)
 130 {
 131         int err;
 132
 133         err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
 134         BUG_ON(err);
 135 }
 136
 137 module_init(xfrm6_tunnel_init);
 138 module_exit(xfrm6_tunnel_exit);
 139 MODULE_LICENSE("GPL");
 140 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);