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
  25        if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
  26                goto out;
  27
  28        if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)
  29                goto out;
  30
  31        mtu = dst_mtu(skb_dst(skb));
  32        if (skb->len > mtu) {
  33                if (skb->sk)
  34                        xfrm_local_error(skb, mtu);
  35                else
  36                        icmp_send(skb, ICMP_DEST_UNREACH,
  37                                  ICMP_FRAG_NEEDED, htonl(mtu));
  38                ret = -EMSGSIZE;
  39        }
  40out:
  41        return ret;
  42}
  43
  44int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  45{
  46        int err;
  47
  48        err = xfrm4_tunnel_check_size(skb);
  49        if (err)
  50                return err;
  51
  52        XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
  53
  54        return xfrm4_extract_header(skb);
  55}
  56
  57int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
  58{
  59        int err;
  60
  61        err = xfrm_inner_extract_output(x, skb);
  62        if (err)
  63                return err;
  64
  65        memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
  66        IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;
  67
  68        skb->protocol = htons(ETH_P_IP);
  69
  70        return x->outer_mode->output2(x, skb);
  71}
  72EXPORT_SYMBOL(xfrm4_prepare_output);
  73
  74int xfrm4_output_finish(struct sk_buff *skb)
  75{
  76#ifdef CONFIG_NETFILTER
  77        if (!skb_dst(skb)->xfrm) {
  78                IPCB(skb)->flags |= IPSKB_REROUTED;
  79                return dst_output(skb);
  80        }
  81
  82        IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
  83#endif
  84
  85        skb->protocol = htons(ETH_P_IP);
  86        return xfrm_output(skb);
  87}
  88
  89int xfrm4_output(struct sk_buff *skb)
  90{
  91        struct dst_entry *dst = skb_dst(skb);
  92        struct xfrm_state *x = dst->xfrm;
  93
  94        return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb,
  95                            NULL, dst->dev,
  96                            x->outer_mode->afinfo->output_finish,
  97                            !(IPCB(skb)->flags & IPSKB_REROUTED));
  98}
  99
 100void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
 101{
 102        struct iphdr *hdr;
 103
 104        hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
 105        ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
 106                       inet_sk(skb->sk)->inet_dport, mtu);
 107}
 108