iptable_filter.c revision 666953df353194bef76086fa3f126241cbac3e3a
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 .lock = RW_LOCK_UNLOCKED, 60 .me = THIS_MODULE, 61 .af = AF_INET, 62}; 63 64/* The work comes in here from netfilter.c. */ 65static unsigned int 66ipt_local_in_hook(unsigned int hook, 67 struct sk_buff *skb, 68 const struct net_device *in, 69 const struct net_device *out, 70 int (*okfn)(struct sk_buff *)) 71{ 72 return ipt_do_table(skb, hook, in, out, 73 nf_local_in_net(in, out)->ipv4.iptable_filter); 74} 75 76static unsigned int 77ipt_hook(unsigned int hook, 78 struct sk_buff *skb, 79 const struct net_device *in, 80 const struct net_device *out, 81 int (*okfn)(struct sk_buff *)) 82{ 83 return ipt_do_table(skb, hook, in, out, 84 nf_forward_net(in, out)->ipv4.iptable_filter); 85} 86 87static unsigned int 88ipt_local_out_hook(unsigned int hook, 89 struct sk_buff *skb, 90 const struct net_device *in, 91 const struct net_device *out, 92 int (*okfn)(struct sk_buff *)) 93{ 94 /* root is playing with raw sockets. */ 95 if (skb->len < sizeof(struct iphdr) || 96 ip_hdrlen(skb) < sizeof(struct iphdr)) { 97 if (net_ratelimit()) 98 printk("iptable_filter: ignoring short SOCK_RAW " 99 "packet.\n"); 100 return NF_ACCEPT; 101 } 102 103 return ipt_do_table(skb, hook, in, out, 104 nf_local_out_net(in, out)->ipv4.iptable_filter); 105} 106 107static struct nf_hook_ops ipt_ops[] __read_mostly = { 108 { 109 .hook = ipt_local_in_hook, 110 .owner = THIS_MODULE, 111 .pf = PF_INET, 112 .hooknum = NF_INET_LOCAL_IN, 113 .priority = NF_IP_PRI_FILTER, 114 }, 115 { 116 .hook = ipt_hook, 117 .owner = THIS_MODULE, 118 .pf = PF_INET, 119 .hooknum = NF_INET_FORWARD, 120 .priority = NF_IP_PRI_FILTER, 121 }, 122 { 123 .hook = ipt_local_out_hook, 124 .owner = THIS_MODULE, 125 .pf = PF_INET, 126 .hooknum = NF_INET_LOCAL_OUT, 127 .priority = NF_IP_PRI_FILTER, 128 }, 129}; 130 131/* Default to forward because I got too much mail already. */ 132static int forward = NF_ACCEPT; 133module_param(forward, bool, 0000); 134 135static int __net_init iptable_filter_net_init(struct net *net) 136{ 137 /* Register table */ 138 net->ipv4.iptable_filter = 139 ipt_register_table(net, &packet_filter, &initial_table.repl); 140 if (IS_ERR(net->ipv4.iptable_filter)) 141 return PTR_ERR(net->ipv4.iptable_filter); 142 return 0; 143} 144 145static void __net_exit iptable_filter_net_exit(struct net *net) 146{ 147 ipt_unregister_table(net->ipv4.iptable_filter); 148} 149 150static struct pernet_operations iptable_filter_net_ops = { 151 .init = iptable_filter_net_init, 152 .exit = iptable_filter_net_exit, 153}; 154 155static int __init iptable_filter_init(void) 156{ 157 int ret; 158 159 if (forward < 0 || forward > NF_MAX_VERDICT) { 160 printk("iptables forward must be 0 or 1\n"); 161 return -EINVAL; 162 } 163 164 /* Entry 1 is the FORWARD hook */ 165 initial_table.entries[1].target.verdict = -forward - 1; 166 167 ret = register_pernet_subsys(&iptable_filter_net_ops); 168 if (ret < 0) 169 return ret; 170 171 /* Register hooks */ 172 ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); 173 if (ret < 0) 174 goto cleanup_table; 175 176 return ret; 177 178 cleanup_table: 179 unregister_pernet_subsys(&iptable_filter_net_ops); 180 return ret; 181} 182 183static void __exit iptable_filter_fini(void) 184{ 185 nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); 186 unregister_pernet_subsys(&iptable_filter_net_ops); 187} 188 189module_init(iptable_filter_init); 190module_exit(iptable_filter_fini); 191