linux/net/ipv6/xfrm6_mode_tunnel.c
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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/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
  21static 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 */
  34static 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        dsfield = XFRM_MODE_SKB_CB(skb)->tos;
  53        dsfield = INET_ECN_encapsulate(dsfield, dsfield);
  54        if (x->props.flags & XFRM_STATE_NOECN)
  55                dsfield &= ~INET_ECN_MASK;
  56        ipv6_change_dsfield(top_iph, 0, dsfield);
  57        top_iph->hop_limit = ip6_dst_hoplimit(dst->child);
  58        top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
  59        top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
  60        return 0;
  61}
  62
  63static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
  64{
  65        int err = -EINVAL;
  66
  67        if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
  68                goto out;
  69        if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  70                goto out;
  71
  72        if (skb_cloned(skb) &&
  73            (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
  74                goto out;
  75
  76        if (x->props.flags & XFRM_STATE_DECAP_DSCP)
  77                ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
  78                               ipipv6_hdr(skb));
  79        if (!(x->props.flags & XFRM_STATE_NOECN))
  80                ipip6_ecn_decapsulate(skb);
  81
  82        skb_reset_network_header(skb);
  83        skb_mac_header_rebuild(skb);
  84
  85        err = 0;
  86
  87out:
  88        return err;
  89}
  90
  91static 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
 101static int __init xfrm6_mode_tunnel_init(void)
 102{
 103        return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
 104}
 105
 106static 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
 114module_init(xfrm6_mode_tunnel_init);
 115module_exit(xfrm6_mode_tunnel_exit);
 116MODULE_LICENSE("GPL");
 117MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);
 118
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