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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. | |
1da177e4 | 10 | */ |
1da177e4 LT |
11 | #include <linux/module.h> |
12 | #include <linux/netfilter_ipv4/ip_tables.h> | |
13 | #include <linux/netdevice.h> | |
14 | #include <linux/skbuff.h> | |
15 | #include <net/sock.h> | |
16 | #include <net/route.h> | |
17 | #include <linux/ip.h> | |
c9bdd4b5 | 18 | #include <net/ip.h> |
1da177e4 LT |
19 | |
20 | MODULE_LICENSE("GPL"); | |
21 | MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); | |
22 | MODULE_DESCRIPTION("iptables mangle table"); | |
23 | ||
6e23ae2a PM |
24 | #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ |
25 | (1 << NF_INET_LOCAL_IN) | \ | |
26 | (1 << NF_INET_FORWARD) | \ | |
27 | (1 << NF_INET_LOCAL_OUT) | \ | |
28 | (1 << NF_INET_POST_ROUTING)) | |
1da177e4 LT |
29 | |
30 | /* Ouch - five different hooks? Maybe this should be a config option..... -- BC */ | |
31 | static struct | |
32 | { | |
33 | struct ipt_replace repl; | |
34 | struct ipt_standard entries[5]; | |
35 | struct ipt_error term; | |
3c2ad469 PM |
36 | } initial_table __initdata = { |
37 | .repl = { | |
38 | .name = "mangle", | |
39 | .valid_hooks = MANGLE_VALID_HOOKS, | |
40 | .num_entries = 6, | |
41 | .size = sizeof(struct ipt_standard) * 5 + sizeof(struct ipt_error), | |
42 | .hook_entry = { | |
6e23ae2a PM |
43 | [NF_INET_PRE_ROUTING] = 0, |
44 | [NF_INET_LOCAL_IN] = sizeof(struct ipt_standard), | |
45 | [NF_INET_FORWARD] = sizeof(struct ipt_standard) * 2, | |
46 | [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 3, | |
47 | [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard) * 4, | |
3c2ad469 PM |
48 | }, |
49 | .underflow = { | |
6e23ae2a PM |
50 | [NF_INET_PRE_ROUTING] = 0, |
51 | [NF_INET_LOCAL_IN] = sizeof(struct ipt_standard), | |
52 | [NF_INET_FORWARD] = sizeof(struct ipt_standard) * 2, | |
53 | [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 3, | |
54 | [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard) * 4, | |
3c2ad469 PM |
55 | }, |
56 | }, | |
57 | .entries = { | |
58 | IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */ | |
59 | IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_IN */ | |
60 | IPT_STANDARD_INIT(NF_ACCEPT), /* FORWARD */ | |
61 | IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */ | |
62 | IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */ | |
63 | }, | |
64 | .term = IPT_ERROR_INIT, /* ERROR */ | |
1da177e4 LT |
65 | }; |
66 | ||
44d34e72 | 67 | static struct xt_table __packet_mangler = { |
1da177e4 LT |
68 | .name = "mangle", |
69 | .valid_hooks = MANGLE_VALID_HOOKS, | |
70 | .lock = RW_LOCK_UNLOCKED, | |
71 | .me = THIS_MODULE, | |
2e4e6a17 | 72 | .af = AF_INET, |
1da177e4 | 73 | }; |
44d34e72 | 74 | static struct xt_table *packet_mangler; |
1da177e4 LT |
75 | |
76 | /* The work comes in here from netfilter.c. */ | |
77 | static unsigned int | |
78 | ipt_route_hook(unsigned int hook, | |
3db05fea | 79 | struct sk_buff *skb, |
1da177e4 LT |
80 | const struct net_device *in, |
81 | const struct net_device *out, | |
82 | int (*okfn)(struct sk_buff *)) | |
83 | { | |
44d34e72 | 84 | return ipt_do_table(skb, hook, in, out, packet_mangler); |
1da177e4 LT |
85 | } |
86 | ||
87 | static unsigned int | |
88 | ipt_local_hook(unsigned int hook, | |
3db05fea | 89 | struct sk_buff *skb, |
1da177e4 LT |
90 | const struct net_device *in, |
91 | const struct net_device *out, | |
92 | int (*okfn)(struct sk_buff *)) | |
93 | { | |
94 | unsigned int ret; | |
eddc9ec5 | 95 | const struct iphdr *iph; |
1da177e4 | 96 | u_int8_t tos; |
6a19d614 | 97 | __be32 saddr, daddr; |
82e91ffe | 98 | u_int32_t mark; |
1da177e4 LT |
99 | |
100 | /* root is playing with raw sockets. */ | |
3db05fea HX |
101 | if (skb->len < sizeof(struct iphdr) |
102 | || ip_hdrlen(skb) < sizeof(struct iphdr)) { | |
1da177e4 | 103 | if (net_ratelimit()) |
4a176c1a PM |
104 | printk("iptable_mangle: ignoring short SOCK_RAW " |
105 | "packet.\n"); | |
1da177e4 LT |
106 | return NF_ACCEPT; |
107 | } | |
108 | ||
109 | /* Save things which could affect route */ | |
3db05fea HX |
110 | mark = skb->mark; |
111 | iph = ip_hdr(skb); | |
eddc9ec5 ACM |
112 | saddr = iph->saddr; |
113 | daddr = iph->daddr; | |
114 | tos = iph->tos; | |
1da177e4 | 115 | |
44d34e72 | 116 | ret = ipt_do_table(skb, hook, in, out, packet_mangler); |
1da177e4 | 117 | /* Reroute for ANY change. */ |
eddc9ec5 | 118 | if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE) { |
3db05fea | 119 | iph = ip_hdr(skb); |
eddc9ec5 ACM |
120 | |
121 | if (iph->saddr != saddr || | |
122 | iph->daddr != daddr || | |
3db05fea | 123 | skb->mark != mark || |
eddc9ec5 | 124 | iph->tos != tos) |
3db05fea | 125 | if (ip_route_me_harder(skb, RTN_UNSPEC)) |
eddc9ec5 ACM |
126 | ret = NF_DROP; |
127 | } | |
1da177e4 LT |
128 | |
129 | return ret; | |
130 | } | |
131 | ||
1999414a | 132 | static struct nf_hook_ops ipt_ops[] __read_mostly = { |
1da177e4 LT |
133 | { |
134 | .hook = ipt_route_hook, | |
135 | .owner = THIS_MODULE, | |
136 | .pf = PF_INET, | |
6e23ae2a | 137 | .hooknum = NF_INET_PRE_ROUTING, |
1da177e4 LT |
138 | .priority = NF_IP_PRI_MANGLE, |
139 | }, | |
140 | { | |
141 | .hook = ipt_route_hook, | |
142 | .owner = THIS_MODULE, | |
143 | .pf = PF_INET, | |
6e23ae2a | 144 | .hooknum = NF_INET_LOCAL_IN, |
1da177e4 LT |
145 | .priority = NF_IP_PRI_MANGLE, |
146 | }, | |
147 | { | |
148 | .hook = ipt_route_hook, | |
149 | .owner = THIS_MODULE, | |
150 | .pf = PF_INET, | |
6e23ae2a | 151 | .hooknum = NF_INET_FORWARD, |
1da177e4 LT |
152 | .priority = NF_IP_PRI_MANGLE, |
153 | }, | |
154 | { | |
155 | .hook = ipt_local_hook, | |
156 | .owner = THIS_MODULE, | |
157 | .pf = PF_INET, | |
6e23ae2a | 158 | .hooknum = NF_INET_LOCAL_OUT, |
1da177e4 LT |
159 | .priority = NF_IP_PRI_MANGLE, |
160 | }, | |
161 | { | |
162 | .hook = ipt_route_hook, | |
163 | .owner = THIS_MODULE, | |
164 | .pf = PF_INET, | |
6e23ae2a | 165 | .hooknum = NF_INET_POST_ROUTING, |
1da177e4 LT |
166 | .priority = NF_IP_PRI_MANGLE, |
167 | }, | |
168 | }; | |
169 | ||
65b4b4e8 | 170 | static int __init iptable_mangle_init(void) |
1da177e4 LT |
171 | { |
172 | int ret; | |
173 | ||
174 | /* Register table */ | |
44d34e72 AD |
175 | packet_mangler = ipt_register_table(&init_net, &__packet_mangler, |
176 | &initial_table.repl); | |
177 | if (IS_ERR(packet_mangler)) | |
178 | return PTR_ERR(packet_mangler); | |
1da177e4 LT |
179 | |
180 | /* Register hooks */ | |
964ddaa1 | 181 | ret = nf_register_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); |
1da177e4 LT |
182 | if (ret < 0) |
183 | goto cleanup_table; | |
184 | ||
1da177e4 LT |
185 | return ret; |
186 | ||
1da177e4 | 187 | cleanup_table: |
44d34e72 | 188 | ipt_unregister_table(packet_mangler); |
1da177e4 LT |
189 | return ret; |
190 | } | |
191 | ||
65b4b4e8 | 192 | static void __exit iptable_mangle_fini(void) |
1da177e4 | 193 | { |
964ddaa1 | 194 | nf_unregister_hooks(ipt_ops, ARRAY_SIZE(ipt_ops)); |
44d34e72 | 195 | ipt_unregister_table(packet_mangler); |
1da177e4 LT |
196 | } |
197 | ||
65b4b4e8 AM |
198 | module_init(iptable_mangle_init); |
199 | module_exit(iptable_mangle_fini); |