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