iptable_filter.c revision 24c232d8e911ef6189e02da411dc2b72cb03bfcf
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 <net/ip.h> 17 18MODULE_LICENSE("GPL"); 19MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 20MODULE_DESCRIPTION("iptables filter table"); 21 22#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \ 23 (1 << NF_INET_FORWARD) | \ 24 (1 << NF_INET_LOCAL_OUT)) 25 26static struct 27{ 28 struct ipt_replace repl; 29 struct ipt_standard entries[3]; 30 struct ipt_error term; 31} initial_table __net_initdata = { 32 .repl = { 33 .name = "filter", 34 .valid_hooks = FILTER_VALID_HOOKS, 35 .num_entries = 4, 36 .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), 37 .hook_entry = { 38 [NF_INET_LOCAL_IN] = 0, 39 [NF_INET_FORWARD] = sizeof(struct ipt_standard), 40 [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2, 41 }, 42 .underflow = { 43 [NF_INET_LOCAL_IN] = 0, 44 [NF_INET_FORWARD] = sizeof(struct ipt_standard), 45 [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2, 46 }, 47 }, 48 .entries = { 49 IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_IN */ 50 IPT_STANDARD_INIT(NF_ACCEPT), /* FORWARD */ 51 IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */ 52 }, 53 .term = IPT_ERROR_INIT, /* ERROR */ 54}; 55 56static struct xt_table packet_filter = { 57 .name = "filter", 58 .valid_hooks = FILTER_VALID_HOOKS, 59 .me = THIS_MODULE, 60 .af = AF_INET, 61}; 62 63/* The work comes in here from netfilter.c. */ 64static unsigned int 65ipt_local_in_hook(unsigned int hook, 66 struct sk_buff *skb, 67 const struct net_device *in, 68 const struct net_device *out, 69 int (*okfn)(struct sk_buff *)) 70{ 71 return ipt_do_table(skb, hook, in, out, 72 dev_net(in)->ipv4.iptable_filter); 73} 74 75static unsigned int 76ipt_hook(unsigned int hook, 77 struct sk_buff *skb, 78 const struct net_device *in, 79 const struct net_device *out, 80 int (*okfn)(struct sk_buff *)) 81{ 82 return ipt_do_table(skb, hook, in, out, 83 dev_net(in)->ipv4.iptable_filter); 84} 85 86static unsigned int 87ipt_local_out_hook(unsigned int hook, 88 struct sk_buff *skb, 89 const struct net_device *in, 90 const struct net_device *out, 91 int (*okfn)(struct sk_buff *)) 92{ 93 /* root is playing with raw sockets. */ 94 if (skb->len < sizeof(struct iphdr) || 95 ip_hdrlen(skb) < sizeof(struct iphdr)) 96 return NF_ACCEPT; 97 return ipt_do_table(skb, hook, in, out, 98 dev_net(out)->ipv4.iptable_filter); 99} 100 101static struct nf_hook_ops ipt_ops[] __read_mostly = { 102 { 103 .hook = ipt_local_in_hook, 104 .owner = THIS_MODULE, 105 .pf = NFPROTO_IPV4, 106 .hooknum = NF_INET_LOCAL_IN, 107 .priority = NF_IP_PRI_FILTER, 108 }, 109 { 110 .hook = ipt_hook, 111 .owner = THIS_MODULE, 112 .pf = NFPROTO_IPV4, 113 .hooknum = NF_INET_FORWARD, 114 .priority = NF_IP_PRI_FILTER, 115 }, 116 { 117 .hook = ipt_local_out_hook, 118 .owner = THIS_MODULE, 119 .pf = NFPROTO_IPV4, 120 .hooknum = NF_INET_LOCAL_OUT, 121 .priority = NF_IP_PRI_FILTER, 122 }, 123}; 124 125/* Default to forward because I got too much mail already. */ 126static int forward = NF_ACCEPT; 127module_param(forward, bool, 0000); 128 129static int __net_init iptable_filter_net_init(struct net *net) 130{ 131 /* Register table */ 132 net->ipv4.iptable_filter = 133 ipt_register_table(net, &packet_filter, &initial_table.repl); 134 if (IS_ERR(net->ipv4.iptable_filter)) 135 return PTR_ERR(net->ipv4.iptable_filter); 136 return 0; 137} 138 139static void __net_exit iptable_filter_net_exit(struct net *net) 140{ 141 ipt_unregister_table(net->ipv4.iptable_filter); 142} 143 144static struct pernet_operations iptable_filter_net_ops = { 145 .init = iptable_filter_net_init, 146 .exit = iptable_filter_net_exit, 147}; 148 149static int __init iptable_filter_init(void) 150{ 151 int ret; 152 153 if (forward < 0 || forward > NF_MAX_VERDICT) { 154 printk("iptables forward must be 0 or 1\n"); 155 return -EINVAL; 156 } 157 158 /* Entry 1 is the FORWARD hook */ 159 initial_table.entries[1].target.verdict = -forward - 1; 160 161 ret = register_pernet_subsys(&iptable_filter_net_ops); 162 if (ret < 0) 163 return ret; 164 165 /* Register hooks */ 166 ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); 167 if (ret < 0) 168 goto cleanup_table; 169 170 return ret; 171 172 cleanup_table: 173 unregister_pernet_subsys(&iptable_filter_net_ops); 174 return ret; 175} 176 177static void __exit iptable_filter_fini(void) 178{ 179 nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); 180 unregister_pernet_subsys(&iptable_filter_net_ops); 181} 182 183module_init(iptable_filter_init); 184module_exit(iptable_filter_fini); 185