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/nf_conntrack_zones.h>
  20 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
  21 #include <net/netfilter/nf_conntrack.h>
  22
  23 /* Returns new sk_buff, or NULL */
  24 static int nf_ct_ipv4_gather_frags(struct sk_buff *skb, u_int32_t user)
  25 {
  26         int err;
  27
  28         skb_orphan(skb);
  29
  30         local_bh_disable();
  31         err = ip_defrag(skb, user);
  32         local_bh_enable();
  33
  34         if (!err)
  35                 ip_send_check(ip_hdr(skb));
  36
  37         return err;
  38 }
  39
  40 static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
  41                                               struct sk_buff *skb)
  42 {
  43         u16 zone = NF_CT_DEFAULT_ZONE;
  44
  45         if (skb->nfct)
  46                 zone = nf_ct_zone((struct nf_conn *)skb->nfct);
  47
  48 #ifdef CONFIG_BRIDGE_NETFILTER
  49         if (skb->nf_bridge &&
  50             skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)
  51                 return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone;
  52 #endif
  53         if (hooknum == NF_INET_PRE_ROUTING)
  54                 return IP_DEFRAG_CONNTRACK_IN + zone;
  55         else
  56                 return IP_DEFRAG_CONNTRACK_OUT + zone;
  57 }
  58
  59 static unsigned int ipv4_conntrack_defrag(unsigned int hooknum,
  60                                           struct sk_buff *skb,
  61                                           const struct net_device *in,
  62                                           const struct net_device *out,
  63                                           int (*okfn)(struct sk_buff *))
  64 {
  65 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  66 #if !defined(CONFIG_NF_NAT) && !defined(CONFIG_NF_NAT_MODULE)
  67         /* Previously seen (loopback)?  Ignore.  Do this before
  68            fragment check. */
  69         if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
  70                 return NF_ACCEPT;
  71 #endif
  72 #endif
  73         /* Gather fragments. */
  74         if (ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET)) {
  75                 enum ip_defrag_users user = nf_ct_defrag_user(hooknum, skb);
  76                 if (nf_ct_ipv4_gather_frags(skb, user))
  77                         return NF_STOLEN;
  78         }
  79         return NF_ACCEPT;
  80 }
  81
  82 static struct nf_hook_ops ipv4_defrag_ops[] = {
  83         {
  84                 .hook           = ipv4_conntrack_defrag,
  85                 .owner          = THIS_MODULE,
  86                 .pf             = PF_INET,
  87                 .hooknum        = NF_INET_PRE_ROUTING,
  88                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
  89         },
  90         {
  91                 .hook           = ipv4_conntrack_defrag,
  92                 .owner          = THIS_MODULE,
  93                 .pf             = PF_INET,
  94                 .hooknum        = NF_INET_LOCAL_OUT,
  95                 .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
  96         },
  97 };
  98
  99 static int __init nf_defrag_init(void)
 100 {
 101         return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 102 }
 103
 104 static void __exit nf_defrag_fini(void)
 105 {
 106         nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 107 }
 108
 109 void nf_defrag_ipv4_enable(void)
 110 {
 111 }
 112 EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
 113
 114 module_init(nf_defrag_init);
 115 module_exit(nf_defrag_fini);
 116
 117 MODULE_LICENSE("GPL");