Merge branch 'fix/asoc' into topic/asoc
[linux-2.6] / 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 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. */
64 static unsigned int
65 ipt_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
75 static unsigned int
76 ipt_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
86 static unsigned int
87 ipt_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
101 static struct nf_hook_ops ipt_ops[] __read_mostly = {
102         {
103                 .hook           = ipt_local_in_hook,
104                 .owner          = THIS_MODULE,
105                 .pf             = PF_INET,
106                 .hooknum        = NF_INET_LOCAL_IN,
107                 .priority       = NF_IP_PRI_FILTER,
108         },
109         {
110                 .hook           = ipt_hook,
111                 .owner          = THIS_MODULE,
112                 .pf             = PF_INET,
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             = PF_INET,
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. */
126 static int forward = NF_ACCEPT;
127 module_param(forward, bool, 0000);
128
129 static 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
139 static void __net_exit iptable_filter_net_exit(struct net *net)
140 {
141         ipt_unregister_table(net->ipv4.iptable_filter);
142 }
143
144 static struct pernet_operations iptable_filter_net_ops = {
145         .init = iptable_filter_net_init,
146         .exit = iptable_filter_net_exit,
147 };
148
149 static 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
177 static 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
183 module_init(iptable_filter_init);
184 module_exit(iptable_filter_fini);