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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 JK |
30 | |
31 | static struct | |
32 | { | |
33 | struct ipt_replace repl; | |
34 | struct ipt_standard entries[3]; | |
35 | struct ipt_error term; | |
36 | } nat_initial_table __initdata = { | |
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 | ||
44d34e72 | 61 | static struct xt_table __nat_table = { |
5b1158e9 JK |
62 | .name = "nat", |
63 | .valid_hooks = NAT_VALID_HOOKS, | |
fdccecd0 | 64 | .lock = __RW_LOCK_UNLOCKED(__nat_table.lock), |
5b1158e9 JK |
65 | .me = THIS_MODULE, |
66 | .af = AF_INET, | |
67 | }; | |
44d34e72 | 68 | static struct xt_table *nat_table; |
5b1158e9 JK |
69 | |
70 | /* Source NAT */ | |
3db05fea | 71 | static unsigned int ipt_snat_target(struct sk_buff *skb, |
5b1158e9 JK |
72 | const struct net_device *in, |
73 | const struct net_device *out, | |
74 | unsigned int hooknum, | |
75 | const struct xt_target *target, | |
76 | const void *targinfo) | |
77 | { | |
78 | struct nf_conn *ct; | |
79 | enum ip_conntrack_info ctinfo; | |
80 | const struct nf_nat_multi_range_compat *mr = targinfo; | |
81 | ||
6e23ae2a | 82 | NF_CT_ASSERT(hooknum == NF_INET_POST_ROUTING); |
5b1158e9 | 83 | |
3db05fea | 84 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 JK |
85 | |
86 | /* Connection must be valid and new. */ | |
87 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || | |
e905a9ed | 88 | ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
5b1158e9 JK |
89 | NF_CT_ASSERT(out); |
90 | ||
cc01dcbd | 91 | return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_SRC); |
5b1158e9 JK |
92 | } |
93 | ||
94 | /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */ | |
95 | static void warn_if_extra_mangle(__be32 dstip, __be32 srcip) | |
96 | { | |
97 | static int warned = 0; | |
98 | struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } }; | |
99 | struct rtable *rt; | |
100 | ||
f206351a | 101 | if (ip_route_output_key(&init_net, &rt, &fl) != 0) |
5b1158e9 JK |
102 | return; |
103 | ||
104 | if (rt->rt_src != srcip && !warned) { | |
105 | printk("NAT: no longer support implicit source local NAT\n"); | |
106 | printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n", | |
107 | NIPQUAD(srcip), NIPQUAD(dstip)); | |
108 | warned = 1; | |
109 | } | |
110 | ip_rt_put(rt); | |
111 | } | |
112 | ||
3db05fea | 113 | static unsigned int ipt_dnat_target(struct sk_buff *skb, |
5b1158e9 JK |
114 | const struct net_device *in, |
115 | const struct net_device *out, | |
116 | unsigned int hooknum, | |
117 | const struct xt_target *target, | |
118 | const void *targinfo) | |
119 | { | |
120 | struct nf_conn *ct; | |
121 | enum ip_conntrack_info ctinfo; | |
122 | const struct nf_nat_multi_range_compat *mr = targinfo; | |
123 | ||
6e23ae2a PM |
124 | NF_CT_ASSERT(hooknum == NF_INET_PRE_ROUTING || |
125 | hooknum == NF_INET_LOCAL_OUT); | |
5b1158e9 | 126 | |
3db05fea | 127 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 JK |
128 | |
129 | /* Connection must be valid and new. */ | |
130 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); | |
131 | ||
6e23ae2a | 132 | if (hooknum == NF_INET_LOCAL_OUT && |
5b1158e9 | 133 | mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) |
3db05fea | 134 | warn_if_extra_mangle(ip_hdr(skb)->daddr, |
5b1158e9 JK |
135 | mr->range[0].min_ip); |
136 | ||
cc01dcbd | 137 | return nf_nat_setup_info(ct, &mr->range[0], IP_NAT_MANIP_DST); |
5b1158e9 JK |
138 | } |
139 | ||
e1931b78 JE |
140 | static bool ipt_snat_checkentry(const char *tablename, |
141 | const void *entry, | |
142 | const struct xt_target *target, | |
143 | void *targinfo, | |
144 | unsigned int hook_mask) | |
5b1158e9 | 145 | { |
3cf93c96 | 146 | const struct nf_nat_multi_range_compat *mr = targinfo; |
5b1158e9 JK |
147 | |
148 | /* Must be a valid range */ | |
149 | if (mr->rangesize != 1) { | |
150 | printk("SNAT: multiple ranges no longer supported\n"); | |
e1931b78 | 151 | return false; |
5b1158e9 | 152 | } |
e1931b78 | 153 | return true; |
5b1158e9 JK |
154 | } |
155 | ||
e1931b78 JE |
156 | static bool ipt_dnat_checkentry(const char *tablename, |
157 | const void *entry, | |
158 | const struct xt_target *target, | |
159 | void *targinfo, | |
160 | unsigned int hook_mask) | |
5b1158e9 | 161 | { |
3cf93c96 | 162 | const struct nf_nat_multi_range_compat *mr = targinfo; |
5b1158e9 JK |
163 | |
164 | /* Must be a valid range */ | |
165 | if (mr->rangesize != 1) { | |
166 | printk("DNAT: multiple ranges no longer supported\n"); | |
e1931b78 | 167 | return false; |
5b1158e9 | 168 | } |
e1931b78 | 169 | return true; |
5b1158e9 JK |
170 | } |
171 | ||
170b197c | 172 | unsigned int |
ba4c7cba | 173 | alloc_null_binding(struct nf_conn *ct, unsigned int hooknum) |
5b1158e9 JK |
174 | { |
175 | /* Force range to this IP; let proto decide mapping for | |
176 | per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). | |
177 | Use reply in case it's already been mangled (eg local packet). | |
178 | */ | |
179 | __be32 ip | |
180 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC | |
181 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip | |
182 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); | |
183 | struct nf_nat_range range | |
184 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } }; | |
185 | ||
0d53778e PM |
186 | pr_debug("Allocating NULL binding for %p (%u.%u.%u.%u)\n", |
187 | ct, NIPQUAD(ip)); | |
cc01dcbd | 188 | return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); |
5b1158e9 JK |
189 | } |
190 | ||
191 | unsigned int | |
ba4c7cba | 192 | alloc_null_binding_confirmed(struct nf_conn *ct, unsigned int hooknum) |
5b1158e9 JK |
193 | { |
194 | __be32 ip | |
195 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC | |
196 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip | |
197 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); | |
a34c4589 | 198 | __be16 all |
5b1158e9 JK |
199 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC |
200 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all | |
201 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all); | |
202 | struct nf_nat_range range | |
203 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } }; | |
204 | ||
0d53778e PM |
205 | pr_debug("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n", |
206 | ct, NIPQUAD(ip)); | |
cc01dcbd | 207 | return nf_nat_setup_info(ct, &range, HOOK2MANIP(hooknum)); |
5b1158e9 JK |
208 | } |
209 | ||
3db05fea | 210 | int nf_nat_rule_find(struct sk_buff *skb, |
5b1158e9 JK |
211 | unsigned int hooknum, |
212 | const struct net_device *in, | |
213 | const struct net_device *out, | |
ba4c7cba | 214 | struct nf_conn *ct) |
5b1158e9 JK |
215 | { |
216 | int ret; | |
217 | ||
44d34e72 | 218 | ret = ipt_do_table(skb, hooknum, in, out, nat_table); |
5b1158e9 JK |
219 | |
220 | if (ret == NF_ACCEPT) { | |
221 | if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) | |
222 | /* NUL mapping */ | |
ba4c7cba | 223 | ret = alloc_null_binding(ct, hooknum); |
5b1158e9 JK |
224 | } |
225 | return ret; | |
226 | } | |
227 | ||
9f15c530 | 228 | static struct xt_target ipt_snat_reg __read_mostly = { |
5b1158e9 JK |
229 | .name = "SNAT", |
230 | .target = ipt_snat_target, | |
231 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
232 | .table = "nat", | |
6e23ae2a | 233 | .hooks = 1 << NF_INET_POST_ROUTING, |
5b1158e9 JK |
234 | .checkentry = ipt_snat_checkentry, |
235 | .family = AF_INET, | |
236 | }; | |
237 | ||
9f15c530 | 238 | static struct xt_target ipt_dnat_reg __read_mostly = { |
5b1158e9 JK |
239 | .name = "DNAT", |
240 | .target = ipt_dnat_target, | |
241 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
242 | .table = "nat", | |
6e23ae2a | 243 | .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT), |
5b1158e9 JK |
244 | .checkentry = ipt_dnat_checkentry, |
245 | .family = AF_INET, | |
246 | }; | |
247 | ||
248 | int __init nf_nat_rule_init(void) | |
249 | { | |
250 | int ret; | |
251 | ||
44d34e72 AD |
252 | nat_table = ipt_register_table(&init_net, &__nat_table, |
253 | &nat_initial_table.repl); | |
254 | if (IS_ERR(nat_table)) | |
255 | return PTR_ERR(nat_table); | |
5b1158e9 JK |
256 | ret = xt_register_target(&ipt_snat_reg); |
257 | if (ret != 0) | |
258 | goto unregister_table; | |
259 | ||
260 | ret = xt_register_target(&ipt_dnat_reg); | |
261 | if (ret != 0) | |
262 | goto unregister_snat; | |
263 | ||
264 | return ret; | |
265 | ||
266 | unregister_snat: | |
267 | xt_unregister_target(&ipt_snat_reg); | |
268 | unregister_table: | |
44d34e72 | 269 | ipt_unregister_table(nat_table); |
5b1158e9 JK |
270 | |
271 | return ret; | |
272 | } | |
273 | ||
274 | void nf_nat_rule_cleanup(void) | |
275 | { | |
276 | xt_unregister_target(&ipt_dnat_reg); | |
277 | xt_unregister_target(&ipt_snat_reg); | |
44d34e72 | 278 | ipt_unregister_table(nat_table); |
5b1158e9 | 279 | } |