netfilter: xtables: use xt_table for hook instantiation
[linux-2.6.git] / net / ipv4 / netfilter / iptable_filter.c
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
18 MODULE_LICENSE("GPL");
19 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
20 MODULE_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
26 static 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
56 static const struct xt_table packet_filter = {
57         .name           = "filter",
58         .valid_hooks    = FILTER_VALID_HOOKS,
59         .me             = THIS_MODULE,
60         .af             = NFPROTO_IPV4,
61         .priority       = NF_IP_PRI_FILTER,
62 };
63
64 static unsigned int
65 iptable_filter_hook(unsigned int hook, struct sk_buff *skb,
66                     const struct net_device *in, const struct net_device *out,
67                     int (*okfn)(struct sk_buff *))
68 {
69         const struct net *net;
70
71         if (hook == NF_INET_LOCAL_OUT &&
72             (skb->len < sizeof(struct iphdr) ||
73              ip_hdrlen(skb) < sizeof(struct iphdr)))
74                 /* root is playing with raw sockets. */
75                 return NF_ACCEPT;
76
77         net = dev_net((in != NULL) ? in : out);
78         return ipt_do_table(skb, hook, in, out, net->ipv4.iptable_filter);
79 }
80
81 static struct nf_hook_ops *filter_ops __read_mostly;
82
83 /* Default to forward because I got too much mail already. */
84 static int forward = NF_ACCEPT;
85 module_param(forward, bool, 0000);
86
87 static int __net_init iptable_filter_net_init(struct net *net)
88 {
89         /* Register table */
90         net->ipv4.iptable_filter =
91                 ipt_register_table(net, &packet_filter, &initial_table.repl);
92         if (IS_ERR(net->ipv4.iptable_filter))
93                 return PTR_ERR(net->ipv4.iptable_filter);
94         return 0;
95 }
96
97 static void __net_exit iptable_filter_net_exit(struct net *net)
98 {
99         ipt_unregister_table(net, net->ipv4.iptable_filter);
100 }
101
102 static struct pernet_operations iptable_filter_net_ops = {
103         .init = iptable_filter_net_init,
104         .exit = iptable_filter_net_exit,
105 };
106
107 static int __init iptable_filter_init(void)
108 {
109         int ret;
110
111         if (forward < 0 || forward > NF_MAX_VERDICT) {
112                 printk("iptables forward must be 0 or 1\n");
113                 return -EINVAL;
114         }
115
116         /* Entry 1 is the FORWARD hook */
117         initial_table.entries[1].target.verdict = -forward - 1;
118
119         ret = register_pernet_subsys(&iptable_filter_net_ops);
120         if (ret < 0)
121                 return ret;
122
123         /* Register hooks */
124         filter_ops = xt_hook_link(&packet_filter, iptable_filter_hook);
125         if (IS_ERR(filter_ops)) {
126                 ret = PTR_ERR(filter_ops);
127                 goto cleanup_table;
128         }
129
130         return ret;
131
132  cleanup_table:
133         unregister_pernet_subsys(&iptable_filter_net_ops);
134         return ret;
135 }
136
137 static void __exit iptable_filter_fini(void)
138 {
139         xt_hook_unlink(&packet_filter, filter_ops);
140         unregister_pernet_subsys(&iptable_filter_net_ops);
141 }
142
143 module_init(iptable_filter_init);
144 module_exit(iptable_filter_fini);