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 19 MODULE_LICENSE("GPL"); 20 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 21 MODULE_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 static int __net_init iptable_filter_table_init(struct net *net); 27 28 static const struct xt_table packet_filter = { 29 .name = "filter", 30 .valid_hooks = FILTER_VALID_HOOKS, 31 .me = THIS_MODULE, 32 .af = NFPROTO_IPV4, 33 .priority = NF_IP_PRI_FILTER, 34 .table_init = iptable_filter_table_init, 35 }; 36 37 static unsigned int 38 iptable_filter_hook(void *priv, struct sk_buff *skb, 39 const struct nf_hook_state *state) 40 { 41 return ipt_do_table(skb, state, state->net->ipv4.iptable_filter); 42 } 43 44 static struct nf_hook_ops *filter_ops __read_mostly; 45 46 /* Default to forward because I got too much mail already. */ 47 static bool forward __read_mostly = true; 48 module_param(forward, bool, 0000); 49 50 static int __net_init iptable_filter_table_init(struct net *net) 51 { 52 struct ipt_replace *repl; 53 int err; 54 55 if (net->ipv4.iptable_filter) 56 return 0; 57 58 repl = ipt_alloc_initial_table(&packet_filter); 59 if (repl == NULL) 60 return -ENOMEM; 61 /* Entry 1 is the FORWARD hook */ 62 ((struct ipt_standard *)repl->entries)[1].target.verdict = 63 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1; 64 65 err = ipt_register_table(net, &packet_filter, repl, filter_ops, 66 &net->ipv4.iptable_filter); 67 kfree(repl); 68 return err; 69 } 70 71 static int __net_init iptable_filter_net_init(struct net *net) 72 { 73 if (net == &init_net || !forward) 74 return iptable_filter_table_init(net); 75 76 return 0; 77 } 78 79 static void __net_exit iptable_filter_net_exit(struct net *net) 80 { 81 if (!net->ipv4.iptable_filter) 82 return; 83 ipt_unregister_table(net, net->ipv4.iptable_filter, filter_ops); 84 net->ipv4.iptable_filter = NULL; 85 } 86 87 static struct pernet_operations iptable_filter_net_ops = { 88 .init = iptable_filter_net_init, 89 .exit = iptable_filter_net_exit, 90 }; 91 92 static int __init iptable_filter_init(void) 93 { 94 int ret; 95 96 filter_ops = xt_hook_ops_alloc(&packet_filter, iptable_filter_hook); 97 if (IS_ERR(filter_ops)) 98 return PTR_ERR(filter_ops); 99 100 ret = register_pernet_subsys(&iptable_filter_net_ops); 101 if (ret < 0) 102 kfree(filter_ops); 103 104 return ret; 105 } 106 107 static void __exit iptable_filter_fini(void) 108 { 109 unregister_pernet_subsys(&iptable_filter_net_ops); 110 kfree(filter_ops); 111 } 112 113 module_init(iptable_filter_init); 114 module_exit(iptable_filter_fini); 115