LXR linux/net/ipv4/netfilter/iptable

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
   4 *
   5 * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   6 * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
   7 */
   8
   9#include <linux/module.h>
  10#include <linux/moduleparam.h>
  11#include <linux/netfilter_ipv4/ip_tables.h>
  12#include <linux/slab.h>
  13#include <net/ip.h>
  14
  15MODULE_LICENSE("GPL");
  16MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  17MODULE_DESCRIPTION("iptables filter table");
  18
  19#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
  20                            (1 << NF_INET_FORWARD) | \
  21                            (1 << NF_INET_LOCAL_OUT))
  22
  23static const struct xt_table packet_filter = {
  24        .name           = "filter",
  25        .valid_hooks    = FILTER_VALID_HOOKS,
  26        .me             = THIS_MODULE,
  27        .af             = NFPROTO_IPV4,
  28        .priority       = NF_IP_PRI_FILTER,
  29};
  30
  31static unsigned int
  32iptable_filter_hook(void *priv, struct sk_buff *skb,
  33                    const struct nf_hook_state *state)
  34{
  35        return ipt_do_table(skb, state, priv);
  36}
  37
  38static struct nf_hook_ops *filter_ops __read_mostly;
  39
  40/* Default to forward because I got too much mail already. */
  41static bool forward __read_mostly = true;
  42module_param(forward, bool, 0000);
  43
  44static int iptable_filter_table_init(struct net *net)
  45{
  46        struct ipt_replace *repl;
  47        int err;
  48
  49        repl = ipt_alloc_initial_table(&packet_filter);
  50        if (repl == NULL)
  51                return -ENOMEM;
  52        /* Entry 1 is the FORWARD hook */
  53        ((struct ipt_standard *)repl->entries)[1].target.verdict =
  54                forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
  55
  56        err = ipt_register_table(net, &packet_filter, repl, filter_ops);
  57        kfree(repl);
  58        return err;
  59}
  60
  61static int __net_init iptable_filter_net_init(struct net *net)
  62{
  63        if (!forward)
  64                return iptable_filter_table_init(net);
  65
  66        return 0;
  67}
  68
  69static void __net_exit iptable_filter_net_pre_exit(struct net *net)
  70{
  71        ipt_unregister_table_pre_exit(net, "filter");
  72}
  73
  74static void __net_exit iptable_filter_net_exit(struct net *net)
  75{
  76        ipt_unregister_table_exit(net, "filter");
  77}
  78
  79static struct pernet_operations iptable_filter_net_ops = {
  80        .init = iptable_filter_net_init,
  81        .pre_exit = iptable_filter_net_pre_exit,
  82        .exit = iptable_filter_net_exit,
  83};
  84
  85static int __init iptable_filter_init(void)
  86{
  87        int ret = xt_register_template(&packet_filter,
  88                                       iptable_filter_table_init);
  89
  90        if (ret < 0)
  91                return ret;
  92
  93        filter_ops = xt_hook_ops_alloc(&packet_filter, iptable_filter_hook);
  94        if (IS_ERR(filter_ops)) {
  95                xt_unregister_template(&packet_filter);
  96                return PTR_ERR(filter_ops);
  97        }
  98
  99        ret = register_pernet_subsys(&iptable_filter_net_ops);
 100        if (ret < 0) {
 101                xt_unregister_template(&packet_filter);
 102                kfree(filter_ops);
 103                return ret;
 104        }
 105
 106        return 0;
 107}
 108
 109static void __exit iptable_filter_fini(void)
 110{
 111        unregister_pernet_subsys(&iptable_filter_net_ops);
 112        xt_unregister_template(&packet_filter);
 113        kfree(filter_ops);
 114}
 115
 116module_init(iptable_filter_init);
 117module_exit(iptable_filter_fini);
 118