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_is_gso(skb) && skb->len > mtu) ||
  33            (skb_is_gso(skb) &&
  34             !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
  35                skb->protocol = htons(ETH_P_IP);
  36
  37                if (skb->sk)
  38                        xfrm_local_error(skb, mtu);
  39                else
  40                        icmp_send(skb, ICMP_DEST_UNREACH,
  41                                  ICMP_FRAG_NEEDED, htonl(mtu));
  42                ret = -EMSGSIZE;
  43        }
  44out:
  45        return ret;
  46}
  47
  48int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
  49{
  50        int err;
  51
  52        err = xfrm4_tunnel_check_size(skb);
  53        if (err)
  54                return err;
  55
  56        XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
  57
  58        return xfrm4_extract_header(skb);
  59}
  60
  61int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
  62{
  63        int err;
  64
  65        err = xfrm_inner_extract_output(x, skb);
  66        if (err)
  67                return err;
  68
  69        IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
  70        skb->protocol = htons(ETH_P_IP);
  71
  72        return x->outer_mode->output2(x, skb);
  73}
  74EXPORT_SYMBOL(xfrm4_prepare_output);
  75
  76int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb)
  77{
  78        memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
  79
  80#ifdef CONFIG_NETFILTER
  81        IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
  82#endif
  83
  84        return xfrm_output(sk, skb);
  85}
  86
  87static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
  88{
  89        struct xfrm_state *x = skb_dst(skb)->xfrm;
  90
  91#ifdef CONFIG_NETFILTER
  92        if (!x) {
  93                IPCB(skb)->flags |= IPSKB_REROUTED;
  94                return dst_output(net, sk, skb);
  95        }
  96#endif
  97
  98        return x->outer_mode->afinfo->output_finish(sk, skb);
  99}
 100
 101int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 102{
 103        return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 104                            net, sk, skb, NULL, skb_dst(skb)->dev,
 105                            __xfrm4_output,
 106                            !(IPCB(skb)->flags & IPSKB_REROUTED));
 107}
 108
 109void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
 110{
 111        struct iphdr *hdr;
 112
 113        hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
 114        ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
 115                       inet_sk(skb->sk)->inet_dport, mtu);
 116}
 117