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 15 MODULE_LICENSE("GPL"); 16 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 17 MODULE_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 23 static 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 31 static struct nf_hook_ops *filter_ops __read_mostly; 32 33 /* Default to forward because I got too much mail already. */ 34 static bool forward __read_mostly = true; 35 module_param(forward, bool, 0000); 36 37 static int iptable_filter_table_init(struct net *net) 38 { 39 struct ipt_replace *repl; 40 int err; 41 42 repl = ipt_alloc_initial_table(&packet_filter); 43 if (repl == NULL) 44 return -ENOMEM; 45 /* Entry 1 is the FORWARD hook */ 46 ((struct ipt_standard *)repl->entries)[1].target.verdict = 47 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1; 48 49 err = ipt_register_table(net, &packet_filter, repl, filter_ops); 50 kfree(repl); 51 return err; 52 } 53 54 static int __net_init iptable_filter_net_init(struct net *net) 55 { 56 if (!forward) 57 return iptable_filter_table_init(net); 58 59 return 0; 60 } 61 62 static void __net_exit iptable_filter_net_pre_exit(struct net *net) 63 { 64 ipt_unregister_table_pre_exit(net, "filter"); 65 } 66 67 static void __net_exit iptable_filter_net_exit(struct net *net) 68 { 69 ipt_unregister_table_exit(net, "filter"); 70 } 71 72 static struct pernet_operations iptable_filter_net_ops = { 73 .init = iptable_filter_net_init, 74 .pre_exit = iptable_filter_net_pre_exit, 75 .exit = iptable_filter_net_exit, 76 }; 77 78 static int __init iptable_filter_init(void) 79 { 80 int ret = xt_register_template(&packet_filter, 81 iptable_filter_table_init); 82 83 if (ret < 0) 84 return ret; 85 86 filter_ops = xt_hook_ops_alloc(&packet_filter, ipt_do_table); 87 if (IS_ERR(filter_ops)) { 88 xt_unregister_template(&packet_filter); 89 return PTR_ERR(filter_ops); 90 } 91 92 ret = register_pernet_subsys(&iptable_filter_net_ops); 93 if (ret < 0) { 94 xt_unregister_template(&packet_filter); 95 kfree(filter_ops); 96 return ret; 97 } 98 99 return 0; 100 } 101 102 static void __exit iptable_filter_fini(void) 103 { 104 unregister_pernet_subsys(&iptable_filter_net_ops); 105 xt_unregister_template(&packet_filter); 106 kfree(filter_ops); 107 } 108 109 module_init(iptable_filter_init); 110 module_exit(iptable_filter_fini); 111