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 <linux/slab.h> 17#include <net/ip.h> 18 19MODULE_LICENSE("GPL"); 20MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 21MODULE_DESCRIPTION("iptables filter table"); 22 23#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \ 24 (1 << NF_INET_FORWARD) | \ 25 (1 << NF_INET_LOCAL_OUT)) 26 27static const struct xt_table packet_filter = { 28 .name = "filter", 29 .valid_hooks = FILTER_VALID_HOOKS, 30 .me = THIS_MODULE, 31 .af = NFPROTO_IPV4, 32 .priority = NF_IP_PRI_FILTER, 33}; 34 35static unsigned int 36iptable_filter_hook(unsigned int hook, struct sk_buff *skb, 37 const struct net_device *in, const struct net_device *out, 38 int (*okfn)(struct sk_buff *)) 39{ 40 const struct net *net; 41 42 if (hook == NF_INET_LOCAL_OUT && 43 (skb->len < sizeof(struct iphdr) || 44 ip_hdrlen(skb) < sizeof(struct iphdr))) 45 /* root is playing with raw sockets. */ 46 return NF_ACCEPT; 47 48 net = dev_net((in != NULL) ? in : out); 49 return ipt_do_table(skb, hook, in, out, net->ipv4.iptable_filter); 50} 51 52static struct nf_hook_ops *filter_ops __read_mostly; 53 54/* Default to forward because I got too much mail already. */ 55static int forward = NF_ACCEPT; 56module_param(forward, bool, 0000); 57 58static int __net_init iptable_filter_net_init(struct net *net) 59{ 60 struct ipt_replace *repl; 61 62 repl = ipt_alloc_initial_table(&packet_filter); 63 if (repl == NULL) 64 return -ENOMEM; 65 /* Entry 1 is the FORWARD hook */ 66 ((struct ipt_standard *)repl->entries)[1].target.verdict = 67 -forward - 1; 68 69 net->ipv4.iptable_filter = 70 ipt_register_table(net, &packet_filter, repl); 71 kfree(repl); 72 if (IS_ERR(net->ipv4.iptable_filter)) 73 return PTR_ERR(net->ipv4.iptable_filter); 74 return 0; 75} 76 77static void __net_exit iptable_filter_net_exit(struct net *net) 78{ 79 ipt_unregister_table(net, net->ipv4.iptable_filter); 80} 81 82static struct pernet_operations iptable_filter_net_ops = { 83 .init = iptable_filter_net_init, 84 .exit = iptable_filter_net_exit, 85}; 86 87static int __init iptable_filter_init(void) 88{ 89 int ret; 90 91 if (forward < 0 || forward > NF_MAX_VERDICT) { 92 pr_err("iptables forward must be 0 or 1\n"); 93 return -EINVAL; 94 } 95 96 ret = register_pernet_subsys(&iptable_filter_net_ops); 97 if (ret < 0) 98 return ret; 99 100 /* Register hooks */ 101 filter_ops = xt_hook_link(&packet_filter, iptable_filter_hook); 102 if (IS_ERR(filter_ops)) { 103 ret = PTR_ERR(filter_ops); 104 goto cleanup_table; 105 } 106 107 return ret; 108 109 cleanup_table: 110 unregister_pernet_subsys(&iptable_filter_net_ops); 111 return ret; 112} 113 114static void __exit iptable_filter_fini(void) 115{ 116 xt_hook_unlink(&packet_filter, filter_ops); 117 unregister_pernet_subsys(&iptable_filter_net_ops); 118} 119 120module_init(iptable_filter_init); 121module_exit(iptable_filter_fini); 122