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1da177e4 LT |
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> | |
c9bdd4b5 | 16 | #include <net/ip.h> |
1da177e4 LT |
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_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | (1 << NF_IP_LOCAL_OUT)) | |
23 | ||
24 | static struct | |
25 | { | |
26 | struct ipt_replace repl; | |
27 | struct ipt_standard entries[3]; | |
28 | struct ipt_error term; | |
3c2ad469 PM |
29 | } initial_table __initdata = { |
30 | .repl = { | |
31 | .name = "filter", | |
32 | .valid_hooks = FILTER_VALID_HOOKS, | |
33 | .num_entries = 4, | |
34 | .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), | |
35 | .hook_entry = { | |
36 | [NF_IP_LOCAL_IN] = 0, | |
37 | [NF_IP_FORWARD] = sizeof(struct ipt_standard), | |
38 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2, | |
39 | }, | |
40 | .underflow = { | |
41 | [NF_IP_LOCAL_IN] = 0, | |
42 | [NF_IP_FORWARD] = sizeof(struct ipt_standard), | |
43 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2, | |
44 | }, | |
45 | }, | |
46 | .entries = { | |
47 | IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_IN */ | |
48 | IPT_STANDARD_INIT(NF_ACCEPT), /* FORWARD */ | |
49 | IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */ | |
50 | }, | |
51 | .term = IPT_ERROR_INIT, /* ERROR */ | |
1da177e4 LT |
52 | }; |
53 | ||
e60a13e0 | 54 | static struct xt_table packet_filter = { |
1da177e4 LT |
55 | .name = "filter", |
56 | .valid_hooks = FILTER_VALID_HOOKS, | |
57 | .lock = RW_LOCK_UNLOCKED, | |
2e4e6a17 HW |
58 | .me = THIS_MODULE, |
59 | .af = AF_INET, | |
1da177e4 LT |
60 | }; |
61 | ||
62 | /* The work comes in here from netfilter.c. */ | |
63 | static unsigned int | |
64 | ipt_hook(unsigned int hook, | |
3db05fea | 65 | struct sk_buff *skb, |
1da177e4 LT |
66 | const struct net_device *in, |
67 | const struct net_device *out, | |
68 | int (*okfn)(struct sk_buff *)) | |
69 | { | |
3db05fea | 70 | return ipt_do_table(skb, hook, in, out, &packet_filter); |
1da177e4 LT |
71 | } |
72 | ||
73 | static unsigned int | |
74 | ipt_local_out_hook(unsigned int hook, | |
3db05fea | 75 | struct sk_buff *skb, |
1da177e4 LT |
76 | const struct net_device *in, |
77 | const struct net_device *out, | |
78 | int (*okfn)(struct sk_buff *)) | |
79 | { | |
80 | /* root is playing with raw sockets. */ | |
3db05fea HX |
81 | if (skb->len < sizeof(struct iphdr) || |
82 | ip_hdrlen(skb) < sizeof(struct iphdr)) { | |
1da177e4 | 83 | if (net_ratelimit()) |
4a176c1a PM |
84 | printk("iptable_filter: ignoring short SOCK_RAW " |
85 | "packet.\n"); | |
1da177e4 LT |
86 | return NF_ACCEPT; |
87 | } | |
88 | ||
3db05fea | 89 | return ipt_do_table(skb, hook, in, out, &packet_filter); |
1da177e4 LT |
90 | } |
91 | ||
92 | static struct nf_hook_ops ipt_ops[] = { | |
93 | { | |
94 | .hook = ipt_hook, | |
95 | .owner = THIS_MODULE, | |
96 | .pf = PF_INET, | |
97 | .hooknum = NF_IP_LOCAL_IN, | |
98 | .priority = NF_IP_PRI_FILTER, | |
99 | }, | |
100 | { | |
101 | .hook = ipt_hook, | |
102 | .owner = THIS_MODULE, | |
103 | .pf = PF_INET, | |
104 | .hooknum = NF_IP_FORWARD, | |
105 | .priority = NF_IP_PRI_FILTER, | |
106 | }, | |
107 | { | |
108 | .hook = ipt_local_out_hook, | |
109 | .owner = THIS_MODULE, | |
110 | .pf = PF_INET, | |
111 | .hooknum = NF_IP_LOCAL_OUT, | |
112 | .priority = NF_IP_PRI_FILTER, | |
113 | }, | |
114 | }; | |
115 | ||
116 | /* Default to forward because I got too much mail already. */ | |
117 | static int forward = NF_ACCEPT; | |
118 | module_param(forward, bool, 0000); | |
119 | ||
65b4b4e8 | 120 | static int __init iptable_filter_init(void) |
1da177e4 LT |
121 | { |
122 | int ret; | |
123 | ||
124 | if (forward < 0 || forward > NF_MAX_VERDICT) { | |
125 | printk("iptables forward must be 0 or 1\n"); | |
126 | return -EINVAL; | |
127 | } | |
128 | ||
129 | /* Entry 1 is the FORWARD hook */ | |
130 | initial_table.entries[1].target.verdict = -forward - 1; | |
131 | ||
132 | /* Register table */ | |
133 | ret = ipt_register_table(&packet_filter, &initial_table.repl); | |
134 | if (ret < 0) | |
135 | return ret; | |
136 | ||
137 | /* Register hooks */ | |
964ddaa1 | 138 | ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); |
1da177e4 LT |
139 | if (ret < 0) |
140 | goto cleanup_table; | |
141 | ||
1da177e4 LT |
142 | return ret; |
143 | ||
1da177e4 LT |
144 | cleanup_table: |
145 | ipt_unregister_table(&packet_filter); | |
1da177e4 LT |
146 | return ret; |
147 | } | |
148 | ||
65b4b4e8 | 149 | static void __exit iptable_filter_fini(void) |
1da177e4 | 150 | { |
964ddaa1 | 151 | nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); |
1da177e4 LT |
152 | ipt_unregister_table(&packet_filter); |
153 | } | |
154 | ||
65b4b4e8 AM |
155 | module_init(iptable_filter_init); |
156 | module_exit(iptable_filter_fini); |