kernel/net/ipv4/netfilter/iptable_nat.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   3  * (C) 2011 Patrick McHardy <kaber@trash.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/netfilter.h>
  12 #include <linux/netfilter_ipv4.h>
  13 #include <linux/netfilter_ipv4/ip_tables.h>
  14 #include <linux/ip.h>
  15 #include <net/ip.h>
  16
  17 #include <net/netfilter/nf_nat.h>
  18 #include <net/netfilter/nf_nat_core.h>
  19 #include <net/netfilter/nf_nat_l3proto.h>
  20
  21 static const struct xt_table nf_nat_ipv4_table = {
  22         .name           = "nat",
  23         .valid_hooks    = (1 << NF_INET_PRE_ROUTING) |
  24                           (1 << NF_INET_POST_ROUTING) |
  25                           (1 << NF_INET_LOCAL_OUT) |
  26                           (1 << NF_INET_LOCAL_IN),
  27         .me             = THIS_MODULE,
  28         .af             = NFPROTO_IPV4,
  29 };
  30
  31 static unsigned int iptable_nat_do_chain(void *priv,
  32                                          struct sk_buff *skb,
  33                                          const struct nf_hook_state *state,
  34                                          struct nf_conn *ct)
  35 {
  36         return ipt_do_table(skb, state, state->net->ipv4.nat_table);
  37 }
  38
  39 static unsigned int iptable_nat_ipv4_fn(void *priv,
  40                                         struct sk_buff *skb,
  41                                         const struct nf_hook_state *state)
  42 {
  43         return nf_nat_ipv4_fn(priv, skb, state, iptable_nat_do_chain);
  44 }
  45
  46 static unsigned int iptable_nat_ipv4_in(void *priv,
  47                                         struct sk_buff *skb,
  48                                         const struct nf_hook_state *state)
  49 {
  50         return nf_nat_ipv4_in(priv, skb, state, iptable_nat_do_chain);
  51 }
  52
  53 static unsigned int iptable_nat_ipv4_out(void *priv,
  54                                          struct sk_buff *skb,
  55                                          const struct nf_hook_state *state)
  56 {
  57         return nf_nat_ipv4_out(priv, skb, state, iptable_nat_do_chain);
  58 }
  59
  60 static unsigned int iptable_nat_ipv4_local_fn(void *priv,
  61                                               struct sk_buff *skb,
  62                                               const struct nf_hook_state *state)
  63 {
  64         return nf_nat_ipv4_local_fn(priv, skb, state, iptable_nat_do_chain);
  65 }
  66
  67 static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = {
  68         /* Before packet filtering, change destination */
  69         {
  70                 .hook           = iptable_nat_ipv4_in,
  71                 .pf             = NFPROTO_IPV4,
  72                 .hooknum        = NF_INET_PRE_ROUTING,
  73                 .priority       = NF_IP_PRI_NAT_DST,
  74         },
  75         /* After packet filtering, change source */
  76         {
  77                 .hook           = iptable_nat_ipv4_out,
  78                 .pf             = NFPROTO_IPV4,
  79                 .hooknum        = NF_INET_POST_ROUTING,
  80                 .priority       = NF_IP_PRI_NAT_SRC,
  81         },
  82         /* Before packet filtering, change destination */
  83         {
  84                 .hook           = iptable_nat_ipv4_local_fn,
  85                 .pf             = NFPROTO_IPV4,
  86                 .hooknum        = NF_INET_LOCAL_OUT,
  87                 .priority       = NF_IP_PRI_NAT_DST,
  88         },
  89         /* After packet filtering, change source */
  90         {
  91                 .hook           = iptable_nat_ipv4_fn,
  92                 .pf             = NFPROTO_IPV4,
  93                 .hooknum        = NF_INET_LOCAL_IN,
  94                 .priority       = NF_IP_PRI_NAT_SRC,
  95         },
  96 };
  97
  98 static int __net_init iptable_nat_net_init(struct net *net)
  99 {
 100         struct ipt_replace *repl;
 101
 102         repl = ipt_alloc_initial_table(&nf_nat_ipv4_table);
 103         if (repl == NULL)
 104                 return -ENOMEM;
 105         net->ipv4.nat_table = ipt_register_table(net, &nf_nat_ipv4_table, repl);
 106         kfree(repl);
 107         return PTR_ERR_OR_ZERO(net->ipv4.nat_table);
 108 }
 109
 110 static void __net_exit iptable_nat_net_exit(struct net *net)
 111 {
 112         ipt_unregister_table(net, net->ipv4.nat_table);
 113 }
 114
 115 static struct pernet_operations iptable_nat_net_ops = {
 116         .init   = iptable_nat_net_init,
 117         .exit   = iptable_nat_net_exit,
 118 };
 119
 120 static int __init iptable_nat_init(void)
 121 {
 122         int err;
 123
 124         err = register_pernet_subsys(&iptable_nat_net_ops);
 125         if (err < 0)
 126                 goto err1;
 127
 128         err = nf_register_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
 129         if (err < 0)
 130                 goto err2;
 131         return 0;
 132
 133 err2:
 134         unregister_pernet_subsys(&iptable_nat_net_ops);
 135 err1:
 136         return err;
 137 }
 138
 139 static void __exit iptable_nat_exit(void)
 140 {
 141         nf_unregister_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
 142         unregister_pernet_subsys(&iptable_nat_net_ops);
 143 }
 144
 145 module_init(iptable_nat_init);
 146 module_exit(iptable_nat_exit);
 147
 148 MODULE_LICENSE("GPL");