LXR linux/net/ipv4/xfrm4

   1/*
   2 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
   3 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License
   7 * as published by the Free Software Foundation; either version
   8 * 2 of the License, or (at your option) any later version.
   9 */
  10
  11#include <linux/if_ether.h>
  12#include <linux/kernel.h>
  13#include <linux/module.h>
  14#include <linux/skbuff.h>
  15#include <linux/netfilter_ipv4.h>
  16#include <net/dst.h>
  17#include <net/ip.h>
  18#include <net/xfrm.h>
  19#include <net/icmp.h>
  20
  21static int xfrm4_tunnel_check_size(struct sk_buff *skb)
  22{
  23        int mtu, ret = 0;
  24        struct dst_entry *dst;
  25
  26        if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
  27                goto out;
  28
  29        if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
  30                goto out;
  31
  32        dst = skb_dst(skb);
  33        mtu = dst_mtu(dst);
  34        if (skb->len > mtu) {
  35                icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
  36                ret = -EMSGSIZE;
  37        }
  38out:
  39        return ret;
  40}
  41
  42int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  43{
  44        int err;
  45
  46        err = xfrm4_tunnel_check_size(skb);
  47        if (err)
  48                return err;
  49
  50        XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
  51
  52        return xfrm4_extract_header(skb);
  53}
  54
  55int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
  56{
  57        int err;
  58
  59        err = xfrm_inner_extract_output(x, skb);
  60        if (err)
  61                return err;
  62
  63        memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
  64        IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;
  65
  66        skb->protocol = htons(ETH_P_IP);
  67
  68        return x->outer_mode->output2(x, skb);
  69}
  70EXPORT_SYMBOL(xfrm4_prepare_output);
  71
  72static int xfrm4_output_finish(struct sk_buff *skb)
  73{
  74#ifdef CONFIG_NETFILTER
  75        if (!skb_dst(skb)->xfrm) {
  76                IPCB(skb)->flags |= IPSKB_REROUTED;
  77                return dst_output(skb);
  78        }
  79
  80        IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
  81#endif
  82
  83        skb->protocol = htons(ETH_P_IP);
  84        return xfrm_output(skb);
  85}
  86
  87int xfrm4_output(struct sk_buff *skb)
  88{
  89        return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb,
  90                            NULL, skb_dst(skb)->dev, xfrm4_output_finish,
  91                            !(IPCB(skb)->flags & IPSKB_REROUTED));
  92}
  93