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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> | |
16 | ||
17 | MODULE_LICENSE("GPL"); | |
18 | MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); | |
19 | MODULE_DESCRIPTION("iptables filter table"); | |
20 | ||
21 | #define FILTER_VALID_HOOKS ((1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | (1 << NF_IP_LOCAL_OUT)) | |
22 | ||
23 | static struct | |
24 | { | |
25 | struct ipt_replace repl; | |
26 | struct ipt_standard entries[3]; | |
27 | struct ipt_error term; | |
28 | } initial_table __initdata | |
29 | = { { "filter", FILTER_VALID_HOOKS, 4, | |
30 | sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), | |
31 | { [NF_IP_LOCAL_IN] = 0, | |
32 | [NF_IP_FORWARD] = sizeof(struct ipt_standard), | |
33 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 }, | |
34 | { [NF_IP_LOCAL_IN] = 0, | |
35 | [NF_IP_FORWARD] = sizeof(struct ipt_standard), | |
36 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 }, | |
37 | 0, NULL, { } }, | |
38 | { | |
39 | /* LOCAL_IN */ | |
40 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, | |
41 | 0, | |
42 | sizeof(struct ipt_entry), | |
43 | sizeof(struct ipt_standard), | |
44 | 0, { 0, 0 }, { } }, | |
45 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, | |
46 | -NF_ACCEPT - 1 } }, | |
47 | /* FORWARD */ | |
48 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, | |
49 | 0, | |
50 | sizeof(struct ipt_entry), | |
51 | sizeof(struct ipt_standard), | |
52 | 0, { 0, 0 }, { } }, | |
53 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, | |
54 | -NF_ACCEPT - 1 } }, | |
55 | /* LOCAL_OUT */ | |
56 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, | |
57 | 0, | |
58 | sizeof(struct ipt_entry), | |
59 | sizeof(struct ipt_standard), | |
60 | 0, { 0, 0 }, { } }, | |
61 | { { { { IPT_ALIGN(sizeof(struct ipt_standard_target)), "" } }, { } }, | |
62 | -NF_ACCEPT - 1 } } | |
63 | }, | |
64 | /* ERROR */ | |
65 | { { { { 0 }, { 0 }, { 0 }, { 0 }, "", "", { 0 }, { 0 }, 0, 0, 0 }, | |
66 | 0, | |
67 | sizeof(struct ipt_entry), | |
68 | sizeof(struct ipt_error), | |
69 | 0, { 0, 0 }, { } }, | |
70 | { { { { IPT_ALIGN(sizeof(struct ipt_error_target)), IPT_ERROR_TARGET } }, | |
71 | { } }, | |
72 | "ERROR" | |
73 | } | |
74 | } | |
75 | }; | |
76 | ||
77 | static struct ipt_table packet_filter = { | |
78 | .name = "filter", | |
79 | .valid_hooks = FILTER_VALID_HOOKS, | |
80 | .lock = RW_LOCK_UNLOCKED, | |
2e4e6a17 HW |
81 | .me = THIS_MODULE, |
82 | .af = AF_INET, | |
1da177e4 LT |
83 | }; |
84 | ||
85 | /* The work comes in here from netfilter.c. */ | |
86 | static unsigned int | |
87 | ipt_hook(unsigned int hook, | |
88 | struct sk_buff **pskb, | |
89 | const struct net_device *in, | |
90 | const struct net_device *out, | |
91 | int (*okfn)(struct sk_buff *)) | |
92 | { | |
93 | return ipt_do_table(pskb, hook, in, out, &packet_filter, NULL); | |
94 | } | |
95 | ||
96 | static unsigned int | |
97 | ipt_local_out_hook(unsigned int hook, | |
98 | struct sk_buff **pskb, | |
99 | const struct net_device *in, | |
100 | const struct net_device *out, | |
101 | int (*okfn)(struct sk_buff *)) | |
102 | { | |
103 | /* root is playing with raw sockets. */ | |
104 | if ((*pskb)->len < sizeof(struct iphdr) | |
105 | || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) { | |
106 | if (net_ratelimit()) | |
107 | printk("ipt_hook: happy cracking.\n"); | |
108 | return NF_ACCEPT; | |
109 | } | |
110 | ||
111 | return ipt_do_table(pskb, hook, in, out, &packet_filter, NULL); | |
112 | } | |
113 | ||
114 | static struct nf_hook_ops ipt_ops[] = { | |
115 | { | |
116 | .hook = ipt_hook, | |
117 | .owner = THIS_MODULE, | |
118 | .pf = PF_INET, | |
119 | .hooknum = NF_IP_LOCAL_IN, | |
120 | .priority = NF_IP_PRI_FILTER, | |
121 | }, | |
122 | { | |
123 | .hook = ipt_hook, | |
124 | .owner = THIS_MODULE, | |
125 | .pf = PF_INET, | |
126 | .hooknum = NF_IP_FORWARD, | |
127 | .priority = NF_IP_PRI_FILTER, | |
128 | }, | |
129 | { | |
130 | .hook = ipt_local_out_hook, | |
131 | .owner = THIS_MODULE, | |
132 | .pf = PF_INET, | |
133 | .hooknum = NF_IP_LOCAL_OUT, | |
134 | .priority = NF_IP_PRI_FILTER, | |
135 | }, | |
136 | }; | |
137 | ||
138 | /* Default to forward because I got too much mail already. */ | |
139 | static int forward = NF_ACCEPT; | |
140 | module_param(forward, bool, 0000); | |
141 | ||
142 | static int __init init(void) | |
143 | { | |
144 | int ret; | |
145 | ||
146 | if (forward < 0 || forward > NF_MAX_VERDICT) { | |
147 | printk("iptables forward must be 0 or 1\n"); | |
148 | return -EINVAL; | |
149 | } | |
150 | ||
151 | /* Entry 1 is the FORWARD hook */ | |
152 | initial_table.entries[1].target.verdict = -forward - 1; | |
153 | ||
154 | /* Register table */ | |
155 | ret = ipt_register_table(&packet_filter, &initial_table.repl); | |
156 | if (ret < 0) | |
157 | return ret; | |
158 | ||
159 | /* Register hooks */ | |
160 | ret = nf_register_hook(&ipt_ops[0]); | |
161 | if (ret < 0) | |
162 | goto cleanup_table; | |
163 | ||
164 | ret = nf_register_hook(&ipt_ops[1]); | |
165 | if (ret < 0) | |
166 | goto cleanup_hook0; | |
167 | ||
168 | ret = nf_register_hook(&ipt_ops[2]); | |
169 | if (ret < 0) | |
170 | goto cleanup_hook1; | |
171 | ||
172 | return ret; | |
173 | ||
174 | cleanup_hook1: | |
175 | nf_unregister_hook(&ipt_ops[1]); | |
176 | cleanup_hook0: | |
177 | nf_unregister_hook(&ipt_ops[0]); | |
178 | cleanup_table: | |
179 | ipt_unregister_table(&packet_filter); | |
180 | ||
181 | return ret; | |
182 | } | |
183 | ||
184 | static void __exit fini(void) | |
185 | { | |
186 | unsigned int i; | |
187 | ||
188 | for (i = 0; i < sizeof(ipt_ops)/sizeof(struct nf_hook_ops); i++) | |
189 | nf_unregister_hook(&ipt_ops[i]); | |
190 | ||
191 | ipt_unregister_table(&packet_filter); | |
192 | } | |
193 | ||
194 | module_init(init); | |
195 | module_exit(fini); |