/net/ipv4/netfilter/nf_defrag_ipv4.c

  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#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 70#if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE)
 71	/* Previously seen (loopback)?  Ignore.  Do this before
 72	   fragment check. */
 73	if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
 74		return NF_ACCEPT;
 75#endif
 76#endif
 77	/* Gather fragments. */
 78	if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
 79		enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb);
 80		if (nf_ct_ipv4_gather_frags(skb, user))
 81			return NF_STOLEN;
 82	}
 83	return NF_ACCEPT;
 84}
 85
 86static struct nf_hook_ops ipv4_defrag_ops[] = {
 87	{
 88		.hook		= ipv4_conntrack_defrag,
 89		.owner		= THIS_MODULE,
 90		.pf		= PF_INET,
 91		.hooknum	= NF_INET_PRE_ROUTING,
 92		.priority	= NF_IP_PRI_CONNTRACK_DEFRAG,
 93	},
 94	{
 95		.hook           = ipv4_conntrack_defrag,
 96		.owner          = THIS_MODULE,
 97		.pf             = PF_INET,
 98		.hooknum        = NF_INET_LOCAL_OUT,
 99		.priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
100	},
101};
102
103static int __init nf_defrag_init(void)
104{
105	return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
106}
107
108static void __exit nf_defrag_fini(void)
109{
110	nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
111}
112
113void nf_defrag_ipv4_enable(void)
114{
115}
116EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
117
118module_init(nf_defrag_init);
119module_exit(nf_defrag_fini);
120
121MODULE_LICENSE("GPL");