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->ignore_df)
  29                goto out;
  30
  31        mtu = dst_mtu(skb_dst(skb));
  32        if (skb->len > mtu) {
  33                skb->protocol = htons(ETH_P_IP);
  34
  35                if (skb->sk)
  36                        xfrm_local_error(skb, mtu);
  37                else
  38                        icmp_send(skb, ICMP_DEST_UNREACH,
  39                                  ICMP_FRAG_NEEDED, htonl(mtu));
  40                ret = -EMSGSIZE;
  41        }
  42out:
  43        return ret;
  44}
  45
  46int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  47{
  48        int err;
  49
  50        err = xfrm4_tunnel_check_size(skb);
  51        if (err)
  52                return err;
  53
  54        XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
  55
  56        return xfrm4_extract_header(skb);
  57}
  58
  59int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
  60{
  61        int err;
  62
  63        err = xfrm_inner_extract_output(x, skb);
  64        if (err)
  65                return err;
  66
  67        IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
  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 sock *sk, struct sk_buff *skb)
  75{
  76        memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
  77
  78#ifdef CONFIG_NETFILTER
  79        IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
  80#endif
  81
  82        return xfrm_output(sk, skb);
  83}
  84
  85static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
  86{
  87        struct xfrm_state *x = skb_dst(skb)->xfrm;
  88
  89#ifdef CONFIG_NETFILTER
  90        if (!x) {
  91                IPCB(skb)->flags |= IPSKB_REROUTED;
  92                return dst_output(net, sk, skb);
  93        }
  94#endif
  95
  96        return x->outer_mode->afinfo->output_finish(sk, skb);
  97}
  98
  99int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 100{
 101        return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 102                            net, sk, skb, NULL, skb_dst(skb)->dev,
 103                            __xfrm4_output,
 104                            !(IPCB(skb)->flags & IPSKB_REROUTED));
 105}
 106
 107void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
 108{
 109        struct iphdr *hdr;
 110
 111        hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
 112        ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
 113                       inet_sk(skb->sk)->inet_dport, mtu);
 114}
 115