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, state->net->ipv4.iptable_filter); 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 if (net->ipv4.iptable_filter) 52 return 0; 53 54 repl = ipt_alloc_initial_table(&packet_filter); 55 if (repl == NULL) 56 return -ENOMEM; 57 /* Entry 1 is the FORWARD hook */ 58 ((struct ipt_standard *)repl->entries)[1].target.verdict = 59 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1; 60 61 err = ipt_register_table(net, &packet_filter, repl, filter_ops, 62 &net->ipv4.iptable_filter); 63 kfree(repl); 64 return err; 65 } 66 67 static int __net_init iptable_filter_net_init(struct net *net) 68 { 69 if (net == &init_net || !forward) 70 return iptable_filter_table_init(net); 71 72 return 0; 73 } 74 75 static void __net_exit iptable_filter_net_pre_exit(struct net *net) 76 { 77 if (net->ipv4.iptable_filter) 78 ipt_unregister_table_pre_exit(net, net->ipv4.iptable_filter, 79 filter_ops); 80 } 81 82 static void __net_exit iptable_filter_net_exit(struct net *net) 83 { 84 if (!net->ipv4.iptable_filter) 85 return; 86 ipt_unregister_table_exit(net, net->ipv4.iptable_filter); 87 net->ipv4.iptable_filter = NULL; 88 } 89 90 static struct pernet_operations iptable_filter_net_ops = { 91 .init = iptable_filter_net_init, 92 .pre_exit = iptable_filter_net_pre_exit, 93 .exit = iptable_filter_net_exit, 94 }; 95 96 static int __init iptable_filter_init(void) 97 { 98 int ret; 99 100 filter_ops = xt_hook_ops_alloc(&packet_filter, iptable_filter_hook); 101 if (IS_ERR(filter_ops)) 102 return PTR_ERR(filter_ops); 103 104 ret = register_pernet_subsys(&iptable_filter_net_ops); 105 if (ret < 0) 106 kfree(filter_ops); 107 108 return ret; 109 } 110 111 static void __exit iptable_filter_fini(void) 112 { 113 unregister_pernet_subsys(&iptable_filter_net_ops); 114 kfree(filter_ops); 115 } 116 117 module_init(iptable_filter_init); 118 module_exit(iptable_filter_fini); 119