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 static int __net_init iptable_filter_table_init(struct net *net); 23 24 static const struct xt_table packet_filter = { 25 .name = "filter", 26 .valid_hooks = FILTER_VALID_HOOKS, 27 .me = THIS_MODULE, 28 .af = NFPROTO_IPV4, 29 .priority = NF_IP_PRI_FILTER, 30 .table_init = iptable_filter_table_init, 31 }; 32 33 static unsigned int 34 iptable_filter_hook(void *priv, struct sk_buff *skb, 35 const struct nf_hook_state *state) 36 { 37 return ipt_do_table(skb, state, priv); 38 } 39 40 static struct nf_hook_ops *filter_ops __read_mostly; 41 42 /* Default to forward because I got too much mail already. */ 43 static bool forward __read_mostly = true; 44 module_param(forward, bool, 0000); 45 46 static int __net_init iptable_filter_table_init(struct net *net) 47 { 48 struct ipt_replace *repl; 49 int err; 50 51 repl = ipt_alloc_initial_table(&packet_filter); 52 if (repl == NULL) 53 return -ENOMEM; 54 /* Entry 1 is the FORWARD hook */ 55 ((struct ipt_standard *)repl->entries)[1].target.verdict = 56 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1; 57 58 err = ipt_register_table(net, &packet_filter, repl, filter_ops); 59 kfree(repl); 60 return err; 61 } 62 63 static int __net_init iptable_filter_net_init(struct net *net) 64 { 65 if (net == &init_net || !forward) 66 return iptable_filter_table_init(net); 67 68 return 0; 69 } 70 71 static void __net_exit iptable_filter_net_pre_exit(struct net *net) 72 { 73 ipt_unregister_table_pre_exit(net, "filter"); 74 } 75 76 static void __net_exit iptable_filter_net_exit(struct net *net) 77 { 78 ipt_unregister_table_exit(net, "filter"); 79 } 80 81 static struct pernet_operations iptable_filter_net_ops = { 82 .init = iptable_filter_net_init, 83 .pre_exit = iptable_filter_net_pre_exit, 84 .exit = iptable_filter_net_exit, 85 }; 86 87 static int __init iptable_filter_init(void) 88 { 89 int ret; 90 91 filter_ops = xt_hook_ops_alloc(&packet_filter, iptable_filter_hook); 92 if (IS_ERR(filter_ops)) 93 return PTR_ERR(filter_ops); 94 95 ret = register_pernet_subsys(&iptable_filter_net_ops); 96 if (ret < 0) 97 kfree(filter_ops); 98 99 return ret; 100 } 101 102 static void __exit iptable_filter_fini(void) 103 { 104 unregister_pernet_subsys(&iptable_filter_net_ops); 105 kfree(filter_ops); 106 } 107 108 module_init(iptable_filter_init); 109 module_exit(iptable_filter_fini); 110