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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 | ||
27 | #if 0 | |
28 | #define DEBUGP printk | |
29 | #else | |
30 | #define DEBUGP(format, args...) | |
31 | #endif | |
32 | ||
33 | #define NAT_VALID_HOOKS ((1<<NF_IP_PRE_ROUTING) | (1<<NF_IP_POST_ROUTING) | (1<<NF_IP_LOCAL_OUT)) | |
34 | ||
35 | static struct | |
36 | { | |
37 | struct ipt_replace repl; | |
38 | struct ipt_standard entries[3]; | |
39 | struct ipt_error term; | |
40 | } nat_initial_table __initdata = { | |
41 | .repl = { | |
42 | .name = "nat", | |
43 | .valid_hooks = NAT_VALID_HOOKS, | |
44 | .num_entries = 4, | |
45 | .size = sizeof(struct ipt_standard) * 3 + sizeof(struct ipt_error), | |
46 | .hook_entry = { | |
47 | [NF_IP_PRE_ROUTING] = 0, | |
48 | [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard), | |
49 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 }, | |
50 | .underflow = { | |
51 | [NF_IP_PRE_ROUTING] = 0, | |
52 | [NF_IP_POST_ROUTING] = sizeof(struct ipt_standard), | |
53 | [NF_IP_LOCAL_OUT] = sizeof(struct ipt_standard) * 2 }, | |
54 | }, | |
55 | .entries = { | |
56 | /* PRE_ROUTING */ | |
57 | { | |
58 | .entry = { | |
59 | .target_offset = sizeof(struct ipt_entry), | |
60 | .next_offset = sizeof(struct ipt_standard), | |
61 | }, | |
62 | .target = { | |
63 | .target = { | |
64 | .u = { | |
65 | .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)), | |
66 | }, | |
67 | }, | |
68 | .verdict = -NF_ACCEPT - 1, | |
69 | }, | |
70 | }, | |
71 | /* POST_ROUTING */ | |
72 | { | |
73 | .entry = { | |
74 | .target_offset = sizeof(struct ipt_entry), | |
75 | .next_offset = sizeof(struct ipt_standard), | |
76 | }, | |
77 | .target = { | |
78 | .target = { | |
79 | .u = { | |
80 | .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)), | |
81 | }, | |
82 | }, | |
83 | .verdict = -NF_ACCEPT - 1, | |
84 | }, | |
85 | }, | |
86 | /* LOCAL_OUT */ | |
87 | { | |
88 | .entry = { | |
89 | .target_offset = sizeof(struct ipt_entry), | |
90 | .next_offset = sizeof(struct ipt_standard), | |
91 | }, | |
92 | .target = { | |
93 | .target = { | |
94 | .u = { | |
95 | .target_size = IPT_ALIGN(sizeof(struct ipt_standard_target)), | |
96 | }, | |
97 | }, | |
98 | .verdict = -NF_ACCEPT - 1, | |
99 | }, | |
100 | }, | |
101 | }, | |
102 | /* ERROR */ | |
103 | .term = { | |
104 | .entry = { | |
105 | .target_offset = sizeof(struct ipt_entry), | |
106 | .next_offset = sizeof(struct ipt_error), | |
107 | }, | |
108 | .target = { | |
109 | .target = { | |
110 | .u = { | |
111 | .user = { | |
112 | .target_size = IPT_ALIGN(sizeof(struct ipt_error_target)), | |
113 | .name = IPT_ERROR_TARGET, | |
114 | }, | |
115 | }, | |
116 | }, | |
117 | .errorname = "ERROR", | |
118 | }, | |
119 | } | |
120 | }; | |
121 | ||
e60a13e0 | 122 | static struct xt_table nat_table = { |
5b1158e9 JK |
123 | .name = "nat", |
124 | .valid_hooks = NAT_VALID_HOOKS, | |
125 | .lock = RW_LOCK_UNLOCKED, | |
126 | .me = THIS_MODULE, | |
127 | .af = AF_INET, | |
128 | }; | |
129 | ||
130 | /* Source NAT */ | |
131 | static unsigned int ipt_snat_target(struct sk_buff **pskb, | |
132 | const struct net_device *in, | |
133 | const struct net_device *out, | |
134 | unsigned int hooknum, | |
135 | const struct xt_target *target, | |
136 | const void *targinfo) | |
137 | { | |
138 | struct nf_conn *ct; | |
139 | enum ip_conntrack_info ctinfo; | |
140 | const struct nf_nat_multi_range_compat *mr = targinfo; | |
141 | ||
142 | NF_CT_ASSERT(hooknum == NF_IP_POST_ROUTING); | |
143 | ||
144 | ct = nf_ct_get(*pskb, &ctinfo); | |
145 | ||
146 | /* Connection must be valid and new. */ | |
147 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || | |
148 | ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); | |
149 | NF_CT_ASSERT(out); | |
150 | ||
151 | return nf_nat_setup_info(ct, &mr->range[0], hooknum); | |
152 | } | |
153 | ||
154 | /* Before 2.6.11 we did implicit source NAT if required. Warn about change. */ | |
155 | static void warn_if_extra_mangle(__be32 dstip, __be32 srcip) | |
156 | { | |
157 | static int warned = 0; | |
158 | struct flowi fl = { .nl_u = { .ip4_u = { .daddr = dstip } } }; | |
159 | struct rtable *rt; | |
160 | ||
161 | if (ip_route_output_key(&rt, &fl) != 0) | |
162 | return; | |
163 | ||
164 | if (rt->rt_src != srcip && !warned) { | |
165 | printk("NAT: no longer support implicit source local NAT\n"); | |
166 | printk("NAT: packet src %u.%u.%u.%u -> dst %u.%u.%u.%u\n", | |
167 | NIPQUAD(srcip), NIPQUAD(dstip)); | |
168 | warned = 1; | |
169 | } | |
170 | ip_rt_put(rt); | |
171 | } | |
172 | ||
173 | static unsigned int ipt_dnat_target(struct sk_buff **pskb, | |
174 | const struct net_device *in, | |
175 | const struct net_device *out, | |
176 | unsigned int hooknum, | |
177 | const struct xt_target *target, | |
178 | const void *targinfo) | |
179 | { | |
180 | struct nf_conn *ct; | |
181 | enum ip_conntrack_info ctinfo; | |
182 | const struct nf_nat_multi_range_compat *mr = targinfo; | |
183 | ||
184 | NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING || | |
185 | hooknum == NF_IP_LOCAL_OUT); | |
186 | ||
187 | ct = nf_ct_get(*pskb, &ctinfo); | |
188 | ||
189 | /* Connection must be valid and new. */ | |
190 | NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)); | |
191 | ||
192 | if (hooknum == NF_IP_LOCAL_OUT && | |
193 | mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) | |
194 | warn_if_extra_mangle((*pskb)->nh.iph->daddr, | |
195 | mr->range[0].min_ip); | |
196 | ||
197 | return nf_nat_setup_info(ct, &mr->range[0], hooknum); | |
198 | } | |
199 | ||
200 | static int ipt_snat_checkentry(const char *tablename, | |
201 | const void *entry, | |
202 | const struct xt_target *target, | |
203 | void *targinfo, | |
204 | unsigned int hook_mask) | |
205 | { | |
206 | struct nf_nat_multi_range_compat *mr = targinfo; | |
207 | ||
208 | /* Must be a valid range */ | |
209 | if (mr->rangesize != 1) { | |
210 | printk("SNAT: multiple ranges no longer supported\n"); | |
211 | return 0; | |
212 | } | |
213 | return 1; | |
214 | } | |
215 | ||
216 | static int ipt_dnat_checkentry(const char *tablename, | |
217 | const void *entry, | |
218 | const struct xt_target *target, | |
219 | void *targinfo, | |
220 | unsigned int hook_mask) | |
221 | { | |
222 | struct nf_nat_multi_range_compat *mr = targinfo; | |
223 | ||
224 | /* Must be a valid range */ | |
225 | if (mr->rangesize != 1) { | |
226 | printk("DNAT: multiple ranges no longer supported\n"); | |
227 | return 0; | |
228 | } | |
41f4689a EL |
229 | if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM) { |
230 | printk("DNAT: port randomization not supported\n"); | |
231 | return 0; | |
232 | } | |
5b1158e9 JK |
233 | return 1; |
234 | } | |
235 | ||
236 | inline unsigned int | |
237 | alloc_null_binding(struct nf_conn *ct, | |
238 | struct nf_nat_info *info, | |
239 | unsigned int hooknum) | |
240 | { | |
241 | /* Force range to this IP; let proto decide mapping for | |
242 | per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED). | |
243 | Use reply in case it's already been mangled (eg local packet). | |
244 | */ | |
245 | __be32 ip | |
246 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC | |
247 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip | |
248 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); | |
249 | struct nf_nat_range range | |
250 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { 0 }, { 0 } }; | |
251 | ||
252 | DEBUGP("Allocating NULL binding for %p (%u.%u.%u.%u)\n", | |
253 | ct, NIPQUAD(ip)); | |
254 | return nf_nat_setup_info(ct, &range, hooknum); | |
255 | } | |
256 | ||
257 | unsigned int | |
258 | alloc_null_binding_confirmed(struct nf_conn *ct, | |
259 | struct nf_nat_info *info, | |
260 | unsigned int hooknum) | |
261 | { | |
262 | __be32 ip | |
263 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC | |
264 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip | |
265 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip); | |
266 | u_int16_t all | |
267 | = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC | |
268 | ? ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u.all | |
269 | : ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u.all); | |
270 | struct nf_nat_range range | |
271 | = { IP_NAT_RANGE_MAP_IPS, ip, ip, { all }, { all } }; | |
272 | ||
273 | DEBUGP("Allocating NULL binding for confirmed %p (%u.%u.%u.%u)\n", | |
274 | ct, NIPQUAD(ip)); | |
275 | return nf_nat_setup_info(ct, &range, hooknum); | |
276 | } | |
277 | ||
278 | int nf_nat_rule_find(struct sk_buff **pskb, | |
279 | unsigned int hooknum, | |
280 | const struct net_device *in, | |
281 | const struct net_device *out, | |
282 | struct nf_conn *ct, | |
283 | struct nf_nat_info *info) | |
284 | { | |
285 | int ret; | |
286 | ||
287 | ret = ipt_do_table(pskb, hooknum, in, out, &nat_table); | |
288 | ||
289 | if (ret == NF_ACCEPT) { | |
290 | if (!nf_nat_initialized(ct, HOOK2MANIP(hooknum))) | |
291 | /* NUL mapping */ | |
292 | ret = alloc_null_binding(ct, info, hooknum); | |
293 | } | |
294 | return ret; | |
295 | } | |
296 | ||
6709dbbb | 297 | static struct xt_target ipt_snat_reg = { |
5b1158e9 JK |
298 | .name = "SNAT", |
299 | .target = ipt_snat_target, | |
300 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
301 | .table = "nat", | |
302 | .hooks = 1 << NF_IP_POST_ROUTING, | |
303 | .checkentry = ipt_snat_checkentry, | |
304 | .family = AF_INET, | |
305 | }; | |
306 | ||
307 | static struct xt_target ipt_dnat_reg = { | |
308 | .name = "DNAT", | |
309 | .target = ipt_dnat_target, | |
310 | .targetsize = sizeof(struct nf_nat_multi_range_compat), | |
311 | .table = "nat", | |
312 | .hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT), | |
313 | .checkentry = ipt_dnat_checkentry, | |
314 | .family = AF_INET, | |
315 | }; | |
316 | ||
317 | int __init nf_nat_rule_init(void) | |
318 | { | |
319 | int ret; | |
320 | ||
321 | ret = ipt_register_table(&nat_table, &nat_initial_table.repl); | |
322 | if (ret != 0) | |
323 | return ret; | |
324 | ret = xt_register_target(&ipt_snat_reg); | |
325 | if (ret != 0) | |
326 | goto unregister_table; | |
327 | ||
328 | ret = xt_register_target(&ipt_dnat_reg); | |
329 | if (ret != 0) | |
330 | goto unregister_snat; | |
331 | ||
332 | return ret; | |
333 | ||
334 | unregister_snat: | |
335 | xt_unregister_target(&ipt_snat_reg); | |
336 | unregister_table: | |
337 | ipt_unregister_table(&nat_table); | |
338 | ||
339 | return ret; | |
340 | } | |
341 | ||
342 | void nf_nat_rule_cleanup(void) | |
343 | { | |
344 | xt_unregister_target(&ipt_dnat_reg); | |
345 | xt_unregister_target(&ipt_snat_reg); | |
346 | ipt_unregister_table(&nat_table); | |
347 | } |