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 */
  26 static 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
  42 static 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
  63 static 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
  86 static 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
 103 static int __init nf_defrag_init(void)
 104 {
 105         return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 106 }
 107
 108 static void __exit nf_defrag_fini(void)
 109 {
 110         nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 111 }
 112
 113 void nf_defrag_ipv4_enable(void)
 114 {
 115 }
 116 EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
 117
 118 module_init(nf_defrag_init);
 119 module_exit(nf_defrag_fini);
 120
 121 MODULE_LICENSE("GPL");