LXR linux/net/ipv4/netfilter/nf_defrag

   1/* (C) 1999-2001 Paul `Rusty' Russell
   2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9#include <linux/types.h>
  10#include <linux/ip.h>
  11#include <linux/netfilter.h>
  12#include <linux/module.h>
  13#include <linux/skbuff.h>
  14#include <net/route.h>
  15#include <net/ip.h>
  16
  17#include <linux/netfilter_bridge.h>
  18#include <linux/netfilter_ipv4.h>
  19#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
  20#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  21#include <net/netfilter/nf_conntrack.h>
  22#endif
  23#include <net/netfilter/nf_conntrack_zones.h>
  24
  25/* Returns new sk_buff, or NULL */
  26static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
  27{
  28        int err;
  29
  30        skb_orphan(skb);
  31
  32        local_bh_disable();
  33        err = ip_defrag(skb, user);
  34        local_bh_enable();
  35
  36        if (!err)
  37                ip_send_check(ip_hdr(skb));
  38
  39        return err;
  40}
  41
  42static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
  43                                              struct sk_buff *skb)
  44{
  45        u16 zone = NF_CT_DEFAULT_ZONE;
  46
  47#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  48        if (skb->nfct)
  49                zone = nf_ct_zone((struct nf_conn *)skb->nfct);
  50#endif
  51
  52#ifdef CONFIG_BRIDGE_NETFILTER
  53        if (skb->nf_bridge &&
  54            skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
  55                return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone;
  56#endif
  57        if (hooknum == NF_INET_PRE_ROUTING)
  58                return IP_DEFRAG_CONNTRACK_IN + zone;
  59        else
  60                return IP_DEFRAG_CONNTRACK_OUT + zone;
  61}
  62
  63static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
  64                                          struct sk_buff *skb,
  65                                          const struct net_device *in,
  66                                          const struct net_device *out,
  67                                          int (*okfn)(struct sk_buff *))
  68{
  69        struct sock *sk = skb->sk;
  70        struct inet_sock *inet = inet_sk(skb->sk);
  71
  72        if (sk && (sk->sk_family == PF_INET) &&
  73            inet->nodefrag)
  74                return NF_ACCEPT;
  75
  76#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  77#if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE)
  78        /* Previously seen (loopback)?  Ignore.  Do this before
  79           fragment check. */
  80        if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
  81                return NF_ACCEPT;
  82#endif
  83#endif
  84        /* Gather fragments. */
  85        if (ip_is_fragment(ip_hdr(skb))) {
  86                enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb);
  87                if (nf_ct_ipv4_gather_frags(skb, user))
  88                        return NF_STOLEN;
  89        }
  90        return NF_ACCEPT;
  91}
  92
  93static struct nf_hook_ops ipv4_defrag_ops[] = {
  94        {
  95                .hook           = ipv4_conntrack_defrag,
  96                .owner          = THIS_MODULE,
  97                .pf             = NFPROTO_IPV4,
  98                .hooknum        = NF_INET_PRE_ROUTING,
  99                .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
 100        },
 101        {
 102                .hook           = ipv4_conntrack_defrag,
 103                .owner          = THIS_MODULE,
 104                .pf             = NFPROTO_IPV4,
 105                .hooknum        = NF_INET_LOCAL_OUT,
 106                .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
 107        },
 108};
 109
 110static int __init nf_defrag_init(void)
 111{
 112        return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 113}
 114
 115static void __exit nf_defrag_fini(void)
 116{
 117        nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 118}
 119
 120void nf_defrag_ipv4_enable(void)
 121{
 122}
 123EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
 124
 125module_init(nf_defrag_init);
 126module_exit(nf_defrag_fini);
 127
 128MODULE_LICENSE("GPL");
 129