LXR linux/net/ipv6/xfrm6_mode

   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
  19static 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 */
  32static 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
  61static 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
  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