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(const struct nf_hook_ops *ops, 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 (ops->hooknum == 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, ops->hooknum, in, out, 50 net->ipv4.iptable_filter); 51} 52 53static struct nf_hook_ops *filter_ops __read_mostly; 54 55/* Default to forward because I got too much mail already. */ 56static bool forward = true; 57module_param(forward, bool, 0000); 58 59static int __net_init iptable_filter_net_init(struct net *net) 60{ 61 struct ipt_replace *repl; 62 63 repl = ipt_alloc_initial_table(&packet_filter); 64 if (repl == NULL) 65 return -ENOMEM; 66 /* Entry 1 is the FORWARD hook */ 67 ((struct ipt_standard *)repl->entries)[1].target.verdict = 68 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1; 69 70 net->ipv4.iptable_filter = 71 ipt_register_table(net, &packet_filter, repl); 72 kfree(repl); 73 return PTR_ERR_OR_ZERO(net->ipv4.iptable_filter); 74} 75 76static void __net_exit iptable_filter_net_exit(struct net *net) 77{ 78 ipt_unregister_table(net, net->ipv4.iptable_filter); 79} 80 81static struct pernet_operations iptable_filter_net_ops = { 82 .init = iptable_filter_net_init, 83 .exit = iptable_filter_net_exit, 84}; 85 86static int __init iptable_filter_init(void) 87{ 88 int ret; 89 90 ret = register_pernet_subsys(&iptable_filter_net_ops); 91 if (ret < 0) 92 return ret; 93 94 /* Register hooks */ 95 filter_ops = xt_hook_link(&packet_filter, iptable_filter_hook); 96 if (IS_ERR(filter_ops)) { 97 ret = PTR_ERR(filter_ops); 98 unregister_pernet_subsys(&iptable_filter_net_ops); 99 } 100 101 return ret; 102} 103 104static void __exit iptable_filter_fini(void) 105{ 106 xt_hook_unlink(&packet_filter, filter_ops); 107 unregister_pernet_subsys(&iptable_filter_net_ops); 108} 109 110module_init(iptable_filter_init); 111module_exit(iptable_filter_fini); 112