net/ipv4/netfilter/iptable_nat.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2006 Netfilter Core Team <[email protected]>
   3  * (C) 2011 Patrick McHardy <[email protected]>
   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(const struct nf_hook_ops *ops,
  32                                          struct sk_buff *skb,
  33                                          const struct net_device *in,
  34                                          const struct net_device *out,
  35                                          struct nf_conn *ct)
  36 {
  37         struct net *net = nf_ct_net(ct);
  38
  39         return ipt_do_table(skb, ops->hooknum, in, out, net->ipv4.nat_table);
  40 }
  41
  42 static unsigned int iptable_nat_ipv4_fn(const struct nf_hook_ops *ops,
  43                                         struct sk_buff *skb,
  44                                         const struct net_device *in,
  45                                         const struct net_device *out,
  46                                         int (*okfn)(struct sk_buff *))
  47 {
  48         return nf_nat_ipv4_fn(ops, skb, in, out, iptable_nat_do_chain);
  49 }
  50
  51 static unsigned int iptable_nat_ipv4_in(const struct nf_hook_ops *ops,
  52                                         struct sk_buff *skb,
  53                                         const struct net_device *in,
  54                                         const struct net_device *out,
  55                                         int (*okfn)(struct sk_buff *))
  56 {
  57         return nf_nat_ipv4_in(ops, skb, in, out, iptable_nat_do_chain);
  58 }
  59
  60 static unsigned int iptable_nat_ipv4_out(const struct nf_hook_ops *ops,
  61                                          struct sk_buff *skb,
  62                                          const struct net_device *in,
  63                                          const struct net_device *out,
  64                                          int (*okfn)(struct sk_buff *))
  65 {
  66         return nf_nat_ipv4_out(ops, skb, in, out, iptable_nat_do_chain);
  67 }
  68
  69 static unsigned int iptable_nat_ipv4_local_fn(const struct nf_hook_ops *ops,
  70                                               struct sk_buff *skb,
  71                                               const struct net_device *in,
  72                                               const struct net_device *out,
  73                                               int (*okfn)(struct sk_buff *))
  74 {
  75         return nf_nat_ipv4_local_fn(ops, skb, in, out, iptable_nat_do_chain);
  76 }
  77
  78 static struct nf_hook_ops nf_nat_ipv4_ops[] __read_mostly = {
  79         /* Before packet filtering, change destination */
  80         {
  81                 .hook           = iptable_nat_ipv4_in,
  82                 .owner          = THIS_MODULE,
  83                 .pf             = NFPROTO_IPV4,
  84                 .hooknum        = NF_INET_PRE_ROUTING,
  85                 .priority       = NF_IP_PRI_NAT_DST,
  86         },
  87         /* After packet filtering, change source */
  88         {
  89                 .hook           = iptable_nat_ipv4_out,
  90                 .owner          = THIS_MODULE,
  91                 .pf             = NFPROTO_IPV4,
  92                 .hooknum        = NF_INET_POST_ROUTING,
  93                 .priority       = NF_IP_PRI_NAT_SRC,
  94         },
  95         /* Before packet filtering, change destination */
  96         {
  97                 .hook           = iptable_nat_ipv4_local_fn,
  98                 .owner          = THIS_MODULE,
  99                 .pf             = NFPROTO_IPV4,
 100                 .hooknum        = NF_INET_LOCAL_OUT,
 101                 .priority       = NF_IP_PRI_NAT_DST,
 102         },
 103         /* After packet filtering, change source */
 104         {
 105                 .hook           = iptable_nat_ipv4_fn,
 106                 .owner          = THIS_MODULE,
 107                 .pf             = NFPROTO_IPV4,
 108                 .hooknum        = NF_INET_LOCAL_IN,
 109                 .priority       = NF_IP_PRI_NAT_SRC,
 110         },
 111 };
 112
 113 static int __net_init iptable_nat_net_init(struct net *net)
 114 {
 115         struct ipt_replace *repl;
 116
 117         repl = ipt_alloc_initial_table(&nf_nat_ipv4_table);
 118         if (repl == NULL)
 119                 return -ENOMEM;
 120         net->ipv4.nat_table = ipt_register_table(net, &nf_nat_ipv4_table, repl);
 121         kfree(repl);
 122         return PTR_ERR_OR_ZERO(net->ipv4.nat_table);
 123 }
 124
 125 static void __net_exit iptable_nat_net_exit(struct net *net)
 126 {
 127         ipt_unregister_table(net, net->ipv4.nat_table);
 128 }
 129
 130 static struct pernet_operations iptable_nat_net_ops = {
 131         .init   = iptable_nat_net_init,
 132         .exit   = iptable_nat_net_exit,
 133 };
 134
 135 static int __init iptable_nat_init(void)
 136 {
 137         int err;
 138
 139         err = register_pernet_subsys(&iptable_nat_net_ops);
 140         if (err < 0)
 141                 goto err1;
 142
 143         err = nf_register_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
 144         if (err < 0)
 145                 goto err2;
 146         return 0;
 147
 148 err2:
 149         unregister_pernet_subsys(&iptable_nat_net_ops);
 150 err1:
 151         return err;
 152 }
 153
 154 static void __exit iptable_nat_exit(void)
 155 {
 156         nf_unregister_hooks(nf_nat_ipv4_ops, ARRAY_SIZE(nf_nat_ipv4_ops));
 157         unregister_pernet_subsys(&iptable_nat_net_ops);
 158 }
 159
 160 module_init(iptable_nat_init);
 161 module_exit(iptable_nat_exit);
 162
 163 MODULE_LICENSE("GPL");