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5b1158e9 JK |
1 | /* (C) 1999-2001 Paul `Rusty' Russell |
2 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | */ | |
8 | ||
9 | /* Everything about the rules for NAT. */ | |
10 | #include <linux/types.h> | |
11 | #include <linux/ip.h> | |
12 | #include <linux/netfilter.h> | |
13 | #include <linux/netfilter_ipv4.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/kmod.h> | |
16 | #include <linux/skbuff.h> | |
17 | #include <linux/proc_fs.h> | |
18 | #include <net/checksum.h> | |
19 | #include <net/route.h> | |
20 | #include <linux/bitops.h> | |
21 | ||
22 | #include <linux/netfilter_ipv4/ip_tables.h> | |
23 | #include <net/netfilter/nf_nat.h> | |
24 | #include <net/netfilter/nf_nat_core.h> | |
25 | #include <net/netfilter/nf_nat_rule.h> | |
26 | ||
6e23ae2a PM |
27 | #define NAT_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ |
28 | (1 << NF_INET_POST_ROUTING) | \ | |
29 | (1 << NF_INET_LOCAL_OUT)) | |
5b1158e9 | 30 | |
35aad0ff | 31 | static const struct |
5b1158e9 JK |
32 | { |
33 | struct ipt_replace repl; | |
34 | struct ipt_standard entries[3]; | |
35 | struct ipt_error term; | |
e099a173 | 36 | } nat_initial_table __net_initdata = { |
5b1158e9 JK |
37 | .repl = { |
38 | .name = "nat", | |
39 | .valid_hooks = NAT_VALID_HOOKS, | |
40 | .num_entries = 4, | |
41 | .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), | |
42 | .hook_entry = { | |
6e23ae2a PM |
43 | [NF_INET_PRE_ROUTING] = 0, |
44 | [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard), | |
45 | [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 | |
3c2ad469 | 46 | }, |
5b1158e9 | 47 | .underflow = { |
6e23ae2a PM |
48 | [NF_INET_PRE_ROUTING] = 0, |
49 | [NF_INET_POST_ROUTING] = sizeof(struct ipt_standard), | |
50 | [NF_INET_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 | |
3c2ad469 | 51 | }, |
5b1158e9 JK |
52 | }, |
53 | .entries = { | |
3c2ad469 PM |
54 | IPT_STANDARD_INIT(NF_ACCEPT), /* PRE_ROUTING */ |
55 | IPT_STANDARD_INIT(NF_ACCEPT), /* POST_ROUTING */ | |
56 | IPT_STANDARD_INIT(NF_ACCEPT), /* LOCAL_OUT */ | |
5b1158e9 | 57 | }, |
3c2ad469 | 58 | .term = IPT_ERROR_INIT, /* ERROR */ |
5b1158e9 JK |
59 | }; |
60 | ||
35aad0ff | 61 | static const struct xt_table nat_table = { |
5b1158e9 JK |
62 | .name = "nat", |
63 | .valid_hooks = NAT_VALID_HOOKS, | |
5b1158e9 | 64 | .me = THIS_MODULE, |
f88e6a8a | 65 | .af = NFPROTO_IPV4, |
5b1158e9 JK |
66 | }; |
67 | ||
68 | /* Source NAT */ | |
7eb35586 JE |
69 | static unsigned int |
70 | ipt_snat_target(struct sk_buff *skb, const struct xt_target_param *par) | |
5b1158e9 JK |
71 | { |
72 | struct nf_conn *ct; | |
73 | enum ip_conntrack_info ctinfo; | |
7eb35586 | 74 | const struct nf_nat_multi_range_compat *mr = par->targinfo; |
5b1158e9 | 75 | |
7eb35586 | 76 | NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING); |
5b1158e9 | 77 | |
3db05fea | 78 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 JK |
79 | |
80 | /* Connection must be valid and new. */ | |
81 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || | |
e905a9ed | 82 | ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
7eb35586 | 83 | NF_CT_ASSERT(par->out != NULL); |
5b1158e9 | 84 | |
cc01dcbd | 85 | return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC); |
5b1158e9 JK |
86 | } |
87 | ||
7eb35586 JE |
88 | static unsigned int |
89 | ipt_dnat_target(struct sk_buff *skb, const struct xt_target_param *par) | |
5b1158e9 JK |
90 | { |
91 | struct nf_conn *ct; | |
92 | enum ip_conntrack_info ctinfo; | |
7eb35586 | 93 | const struct nf_nat_multi_range_compat *mr = par->targinfo; |
5b1158e9 | 94 | |
7eb35586 JE |
95 | NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING || |
96 | par->hooknum == NF_INET_LOCAL_OUT); | |
5b1158e9 | 97 | |
3db05fea | 98 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 JK |
99 | |
100 | /* Connection must be valid and new. */ | |
101 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); | |
102 | ||
cc01dcbd | 103 | return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST); |
5b1158e9 JK |
104 | } |
105 | ||
af5d6dc2 | 106 | static bool ipt_snat_checkentry(const struct xt_tgchk_param *par) |
5b1158e9 | 107 | { |
af5d6dc2 | 108 | const struct nf_nat_multi_range_compat *mr = par->targinfo; |
5b1158e9 JK |
109 | |
110 | /* Must be a valid range */ | |
111 | if (mr->rangesize != 1) { | |
112 | printk("SNAT: multiple ranges no longer supported\n"); | |
e1931b78 | 113 | return false; |
5b1158e9 | 114 | } |
e1931b78 | 115 | return true; |
5b1158e9 JK |
116 | } |
117 | ||
af5d6dc2 | 118 | static bool ipt_dnat_checkentry(const struct xt_tgchk_param *par) |
5b1158e9 | 119 | { |
af5d6dc2 | 120 | const struct nf_nat_multi_range_compat *mr = par->targinfo; |
5b1158e9 JK |
121 | |
122 | /* Must be a valid range */ | |
123 | if (mr->rangesize != 1) { | |
124 | printk("DNAT: multiple ranges no longer supported\n"); | |
e1931b78 | 125 | return false; |
5b1158e9 | 126 | } |
e1931b78 | 127 | return true; |
5b1158e9 JK |
128 | } |
129 | ||
170b197c | 130 | unsigned int |
ba4c7cba | 131 | alloc_null_binding(struct nf_conn *ct, unsigned int hooknum) |
5b1158e9 JK |
132 | { |
133 | /* Force range to this IP; let proto decide mapping for | |
134 | per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). | |
135 | Use reply in case it's already been mangled (eg local packet). | |
136 | */ | |
137 | __be32 ip | |
138 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC | |
139 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip | |
140 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); | |
141 | struct nf_nat_range range | |
142 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } }; | |
143 | ||
cffee385 | 144 | pr_debug("Allocating NULL binding for %p (%pI4)\n", ct, &ip); |
cc01dcbd | 145 | return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); |
5b1158e9 JK |
146 | } |
147 | ||
3db05fea | 148 | int nf_nat_rule_find(struct sk_buff *skb, |
5b1158e9 JK |
149 | unsigned int hooknum, |
150 | const struct net_device *in, | |
151 | const struct net_device *out, | |
ba4c7cba | 152 | struct nf_conn *ct) |
5b1158e9 | 153 | { |
e099a173 | 154 | struct net *net = nf_ct_net(ct); |
5b1158e9 JK |
155 | int ret; |
156 | ||
e099a173 | 157 | ret = ipt_do_table(skb, hooknum, in, out, net->ipv4.nat_table); |
5b1158e9 JK |
158 | |
159 | if (ret == NF_ACCEPT) { | |
160 | if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) | |
161 | /* NUL mapping */ | |
ba4c7cba | 162 | ret = alloc_null_binding(ct, hooknum); |
5b1158e9 JK |
163 | } |
164 | return ret; | |
165 | } | |
166 | ||
9f15c530 | 167 | static struct xt_target ipt_snat_reg __read_mostly = { |
5b1158e9 JK |
168 | .name = "SNAT", |
169 | .target = ipt_snat_target, | |
170 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
171 | .table = "nat", | |
6e23ae2a | 172 | .hooks = 1 << NF_INET_POST_ROUTING, |
5b1158e9 JK |
173 | .checkentry = ipt_snat_checkentry, |
174 | .family = AF_INET, | |
175 | }; | |
176 | ||
9f15c530 | 177 | static struct xt_target ipt_dnat_reg __read_mostly = { |
5b1158e9 JK |
178 | .name = "DNAT", |
179 | .target = ipt_dnat_target, | |
180 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
181 | .table = "nat", | |
6e23ae2a | 182 | .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT), |
5b1158e9 JK |
183 | .checkentry = ipt_dnat_checkentry, |
184 | .family = AF_INET, | |
185 | }; | |
186 | ||
e099a173 AD |
187 | static int __net_init nf_nat_rule_net_init(struct net *net) |
188 | { | |
189 | net->ipv4.nat_table = ipt_register_table(net, &nat_table, | |
190 | &nat_initial_table.repl); | |
191 | if (IS_ERR(net->ipv4.nat_table)) | |
192 | return PTR_ERR(net->ipv4.nat_table); | |
193 | return 0; | |
194 | } | |
195 | ||
196 | static void __net_exit nf_nat_rule_net_exit(struct net *net) | |
197 | { | |
198 | ipt_unregister_table(net->ipv4.nat_table); | |
199 | } | |
200 | ||
201 | static struct pernet_operations nf_nat_rule_net_ops = { | |
202 | .init = nf_nat_rule_net_init, | |
203 | .exit = nf_nat_rule_net_exit, | |
204 | }; | |
205 | ||
5b1158e9 JK |
206 | int __init nf_nat_rule_init(void) |
207 | { | |
208 | int ret; | |
209 | ||
e099a173 AD |
210 | ret = register_pernet_subsys(&nf_nat_rule_net_ops); |
211 | if (ret != 0) | |
212 | goto out; | |
5b1158e9 JK |
213 | ret = xt_register_target(&ipt_snat_reg); |
214 | if (ret != 0) | |
215 | goto unregister_table; | |
216 | ||
217 | ret = xt_register_target(&ipt_dnat_reg); | |
218 | if (ret != 0) | |
219 | goto unregister_snat; | |
220 | ||
221 | return ret; | |
222 | ||
223 | unregister_snat: | |
224 | xt_unregister_target(&ipt_snat_reg); | |
225 | unregister_table: | |
e099a173 AD |
226 | unregister_pernet_subsys(&nf_nat_rule_net_ops); |
227 | out: | |
5b1158e9 JK |
228 | return ret; |
229 | } | |
230 | ||
231 | void nf_nat_rule_cleanup(void) | |
232 | { | |
233 | xt_unregister_target(&ipt_dnat_reg); | |
234 | xt_unregister_target(&ipt_snat_reg); | |
e099a173 | 235 | unregister_pernet_subsys(&nf_nat_rule_net_ops); |
5b1158e9 | 236 | } |