LXR linux/net/ipv4/netfilter/iptable

   1/*
   2 * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
   3 *
   4 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   5 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 *
  11 */
  12
  13#include <linux/module.h>
  14#include <linux/moduleparam.h>
  15#include <linux/netfilter_ipv4/ip_tables.h>
  16#include <net/ip.h>
  17
  18MODULE_LICENSE("GPL");
  19MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  20MODULE_DESCRIPTION("iptables filter table");
  21
  22#define FILTER_VALID_HOOKS ((1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | (1 << NF_IP_LOCAL_OUT))
  23
  24static struct
  25{
  26        struct ipt_replace repl;
  27        struct ipt_standard entries[3];
  28        struct ipt_error term;
  29} initial_table __initdata = {
  30        .repl = {
  31                .name = "filter",
  32                .valid_hooks = FILTER_VALID_HOOKS,
  33                .num_entries = 4,
  34                .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error),
  35                .hook_entry = {
  36                        [NF_IP_LOCAL_IN] = 0,
  37                        [NF_IP_FORWARD] = sizeof(struct ipt_standard),
  38                        [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
  39                },
  40                .underflow = {
  41                        [NF_IP_LOCAL_IN] = 0,
  42                        [NF_IP_FORWARD] = sizeof(struct ipt_standard),
  43                        [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2,
  44                },
  45        },
  46        .entries = {
  47                IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_IN */
  48                IPT_STANDARD_INIT(NF_ACCEPT),   /* FORWARD */
  49                IPT_STANDARD_INIT(NF_ACCEPT),   /* LOCAL_OUT */
  50        },
  51        .term = IPT_ERROR_INIT,                 /* ERROR */
  52};
  53
  54static struct xt_table packet_filter = {
  55        .name           = "filter",
  56        .valid_hooks    = FILTER_VALID_HOOKS,
  57        .lock           = RW_LOCK_UNLOCKED,
  58        .me             = THIS_MODULE,
  59        .af             = AF_INET,
  60};
  61
  62/* The work comes in here from netfilter.c. */
  63static unsigned int
  64ipt_hook(unsigned int hook,
  65         struct sk_buff *skb,
  66         const struct net_device *in,
  67         const struct net_device *out,
  68         int (*okfn)(struct sk_buff *))
  69{
  70        return ipt_do_table(skb, hook, in, out, &packet_filter);
  71}
  72
  73static unsigned int
  74ipt_local_out_hook(unsigned int hook,
  75                   struct sk_buff *skb,
  76                   const struct net_device *in,
  77                   const struct net_device *out,
  78                   int (*okfn)(struct sk_buff *))
  79{
  80        /* root is playing with raw sockets. */
  81        if (skb->len < sizeof(struct iphdr) ||
  82            ip_hdrlen(skb) < sizeof(struct iphdr)) {
  83                if (net_ratelimit())
  84                        printk("iptable_filter: ignoring short SOCK_RAW "
  85                               "packet.\n");
  86                return NF_ACCEPT;
  87        }
  88
  89        return ipt_do_table(skb, hook, in, out, &packet_filter);
  90}
  91
  92static struct nf_hook_ops ipt_ops[] = {
  93        {
  94                .hook           = ipt_hook,
  95                .owner          = THIS_MODULE,
  96                .pf             = PF_INET,
  97                .hooknum        = NF_IP_LOCAL_IN,
  98                .priority       = NF_IP_PRI_FILTER,
  99        },
 100        {
 101                .hook           = ipt_hook,
 102                .owner          = THIS_MODULE,
 103                .pf             = PF_INET,
 104                .hooknum        = NF_IP_FORWARD,
 105                .priority       = NF_IP_PRI_FILTER,
 106        },
 107        {
 108                .hook           = ipt_local_out_hook,
 109                .owner          = THIS_MODULE,
 110                .pf             = PF_INET,
 111                .hooknum        = NF_IP_LOCAL_OUT,
 112                .priority       = NF_IP_PRI_FILTER,
 113        },
 114};
 115
 116/* Default to forward because I got too much mail already. */
 117static int forward = NF_ACCEPT;
 118module_param(forward, bool, 0000);
 119
 120static int __init iptable_filter_init(void)
 121{
 122        int ret;
 123
 124        if (forward < 0 || forward > NF_MAX_VERDICT) {
 125                printk("iptables forward must be 0 or 1\n");
 126                return -EINVAL;
 127        }
 128
 129        /* Entry 1 is the FORWARD hook */
 130        initial_table.entries[1].target.verdict = -forward - 1;
 131
 132        /* Register table */
 133        ret = ipt_register_table(&packet_filter, &initial_table.repl);
 134        if (ret < 0)
 135                return ret;
 136
 137        /* Register hooks */
 138        ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 139        if (ret < 0)
 140                goto cleanup_table;
 141
 142        return ret;
 143
 144 cleanup_table:
 145        ipt_unregister_table(&packet_filter);
 146        return ret;
 147}
 148
 149static void __exit iptable_filter_fini(void)
 150{
 151        nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops));
 152        ipt_unregister_table(&packet_filter);
 153}
 154
 155module_init(iptable_filter_init);
 156module_exit(iptable_filter_fini);
 157