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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 | #include <linux/types.h> | |
9 | #include <linux/icmp.h> | |
5a0e3ad6 | 10 | #include <linux/gfp.h> |
5b1158e9 JK |
11 | #include <linux/ip.h> |
12 | #include <linux/netfilter.h> | |
13 | #include <linux/netfilter_ipv4.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/skbuff.h> | |
16 | #include <linux/proc_fs.h> | |
17 | #include <net/ip.h> | |
18 | #include <net/checksum.h> | |
19 | #include <linux/spinlock.h> | |
20 | ||
21 | #include <net/netfilter/nf_conntrack.h> | |
22 | #include <net/netfilter/nf_conntrack_core.h> | |
2d59e5ca | 23 | #include <net/netfilter/nf_conntrack_extend.h> |
5b1158e9 JK |
24 | #include <net/netfilter/nf_nat.h> |
25 | #include <net/netfilter/nf_nat_rule.h> | |
26 | #include <net/netfilter/nf_nat_protocol.h> | |
27 | #include <net/netfilter/nf_nat_core.h> | |
28 | #include <net/netfilter/nf_nat_helper.h> | |
29 | #include <linux/netfilter_ipv4/ip_tables.h> | |
30 | ||
5b1158e9 JK |
31 | #ifdef CONFIG_XFRM |
32 | static void nat_decode_session(struct sk_buff *skb, struct flowi *fl) | |
33 | { | |
3073e5ab | 34 | struct flowi4 *fl4 = &fl->u.ip4; |
72b72949 JE |
35 | const struct nf_conn *ct; |
36 | const struct nf_conntrack_tuple *t; | |
5b1158e9 JK |
37 | enum ip_conntrack_info ctinfo; |
38 | enum ip_conntrack_dir dir; | |
39 | unsigned long statusbit; | |
40 | ||
41 | ct = nf_ct_get(skb, &ctinfo); | |
42 | if (ct == NULL) | |
43 | return; | |
44 | dir = CTINFO2DIR(ctinfo); | |
45 | t = &ct->tuplehash[dir].tuple; | |
46 | ||
47 | if (dir == IP_CT_DIR_ORIGINAL) | |
48 | statusbit = IPS_DST_NAT; | |
49 | else | |
50 | statusbit = IPS_SRC_NAT; | |
51 | ||
52 | if (ct->status & statusbit) { | |
3073e5ab | 53 | fl4->daddr = t->dst.u3.ip; |
5b1158e9 | 54 | if (t->dst.protonum == IPPROTO_TCP || |
6185f870 | 55 | t->dst.protonum == IPPROTO_UDP || |
4910a087 | 56 | t->dst.protonum == IPPROTO_UDPLITE || |
9d908a69 PM |
57 | t->dst.protonum == IPPROTO_DCCP || |
58 | t->dst.protonum == IPPROTO_SCTP) | |
9cce96df | 59 | fl4->fl4_dport = t->dst.u.tcp.port; |
5b1158e9 JK |
60 | } |
61 | ||
62 | statusbit ^= IPS_NAT_MASK; | |
63 | ||
64 | if (ct->status & statusbit) { | |
3073e5ab | 65 | fl4->saddr = t->src.u3.ip; |
5b1158e9 | 66 | if (t->dst.protonum == IPPROTO_TCP || |
6185f870 | 67 | t->dst.protonum == IPPROTO_UDP || |
4910a087 | 68 | t->dst.protonum == IPPROTO_UDPLITE || |
9d908a69 PM |
69 | t->dst.protonum == IPPROTO_DCCP || |
70 | t->dst.protonum == IPPROTO_SCTP) | |
9cce96df | 71 | fl4->fl4_sport = t->src.u.tcp.port; |
5b1158e9 JK |
72 | } |
73 | } | |
74 | #endif | |
75 | ||
76 | static unsigned int | |
77 | nf_nat_fn(unsigned int hooknum, | |
3db05fea | 78 | struct sk_buff *skb, |
5b1158e9 JK |
79 | const struct net_device *in, |
80 | const struct net_device *out, | |
81 | int (*okfn)(struct sk_buff *)) | |
82 | { | |
83 | struct nf_conn *ct; | |
84 | enum ip_conntrack_info ctinfo; | |
85 | struct nf_conn_nat *nat; | |
5b1158e9 JK |
86 | /* maniptype == SRC for postrouting. */ |
87 | enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum); | |
88 | ||
89 | /* We never see fragments: conntrack defrags on pre-routing | |
90 | and local-out, and nf_nat_out protects post-routing. */ | |
56f8a75c | 91 | NF_CT_ASSERT(!ip_is_fragment(ip_hdr(skb))); |
5b1158e9 | 92 | |
3db05fea | 93 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 JK |
94 | /* Can't track? It's not due to stress, or conntrack would |
95 | have dropped it. Hence it's the user's responsibilty to | |
96 | packet filter it out, or implement conntrack/NAT for that | |
97 | protocol. 8) --RR */ | |
42cf800c | 98 | if (!ct) |
5b1158e9 | 99 | return NF_ACCEPT; |
5b1158e9 JK |
100 | |
101 | /* Don't try to NAT if this packet is not conntracked */ | |
5bfddbd4 | 102 | if (nf_ct_is_untracked(ct)) |
5b1158e9 JK |
103 | return NF_ACCEPT; |
104 | ||
105 | nat = nfct_nat(ct); | |
2d59e5ca | 106 | if (!nat) { |
8c87238b PM |
107 | /* NAT module was loaded late. */ |
108 | if (nf_ct_is_confirmed(ct)) | |
109 | return NF_ACCEPT; | |
2d59e5ca YK |
110 | nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC); |
111 | if (nat == NULL) { | |
0d53778e | 112 | pr_debug("failed to add NAT extension\n"); |
2d59e5ca YK |
113 | return NF_ACCEPT; |
114 | } | |
115 | } | |
5b1158e9 JK |
116 | |
117 | switch (ctinfo) { | |
118 | case IP_CT_RELATED: | |
fb048833 | 119 | case IP_CT_RELATED_REPLY: |
3db05fea | 120 | if (ip_hdr(skb)->protocol == IPPROTO_ICMP) { |
5b1158e9 | 121 | if (!nf_nat_icmp_reply_translation(ct, ctinfo, |
3db05fea | 122 | hooknum, skb)) |
5b1158e9 JK |
123 | return NF_DROP; |
124 | else | |
125 | return NF_ACCEPT; | |
126 | } | |
127 | /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */ | |
128 | case IP_CT_NEW: | |
5b1158e9 JK |
129 | |
130 | /* Seen it before? This can happen for loopback, retrans, | |
131 | or local packets.. */ | |
132 | if (!nf_nat_initialized(ct, maniptype)) { | |
133 | unsigned int ret; | |
134 | ||
c68cd6cc | 135 | ret = nf_nat_rule_find(skb, hooknum, in, out, ct); |
22068311 | 136 | if (ret != NF_ACCEPT) |
5b1158e9 | 137 | return ret; |
5b1158e9 | 138 | } else |
0d53778e | 139 | pr_debug("Already setup manip %s for ct %p\n", |
cbc9f2f4 | 140 | maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST", |
0d53778e | 141 | ct); |
5b1158e9 JK |
142 | break; |
143 | ||
144 | default: | |
145 | /* ESTABLISHED */ | |
146 | NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED || | |
fb048833 | 147 | ctinfo == IP_CT_ESTABLISHED_REPLY); |
5b1158e9 JK |
148 | } |
149 | ||
3db05fea | 150 | return nf_nat_packet(ct, ctinfo, hooknum, skb); |
5b1158e9 JK |
151 | } |
152 | ||
153 | static unsigned int | |
154 | nf_nat_in(unsigned int hooknum, | |
3db05fea | 155 | struct sk_buff *skb, |
e905a9ed YH |
156 | const struct net_device *in, |
157 | const struct net_device *out, | |
158 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 JK |
159 | { |
160 | unsigned int ret; | |
3db05fea | 161 | __be32 daddr = ip_hdr(skb)->daddr; |
5b1158e9 | 162 | |
3db05fea | 163 | ret = nf_nat_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 164 | if (ret != NF_DROP && ret != NF_STOLEN && |
adf30907 ED |
165 | daddr != ip_hdr(skb)->daddr) |
166 | skb_dst_drop(skb); | |
167 | ||
5b1158e9 JK |
168 | return ret; |
169 | } | |
170 | ||
171 | static unsigned int | |
172 | nf_nat_out(unsigned int hooknum, | |
3db05fea | 173 | struct sk_buff *skb, |
5b1158e9 JK |
174 | const struct net_device *in, |
175 | const struct net_device *out, | |
176 | int (*okfn)(struct sk_buff *)) | |
177 | { | |
178 | #ifdef CONFIG_XFRM | |
72b72949 | 179 | const struct nf_conn *ct; |
5b1158e9 JK |
180 | enum ip_conntrack_info ctinfo; |
181 | #endif | |
182 | unsigned int ret; | |
183 | ||
184 | /* root is playing with raw sockets. */ | |
3db05fea HX |
185 | if (skb->len < sizeof(struct iphdr) || |
186 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
187 | return NF_ACCEPT; |
188 | ||
3db05fea | 189 | ret = nf_nat_fn(hooknum, skb, in, out, okfn); |
5b1158e9 JK |
190 | #ifdef CONFIG_XFRM |
191 | if (ret != NF_DROP && ret != NF_STOLEN && | |
3db05fea | 192 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
193 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
194 | ||
3666ed1c JP |
195 | if ((ct->tuplehash[dir].tuple.src.u3.ip != |
196 | ct->tuplehash[!dir].tuple.dst.u3.ip) || | |
197 | (ct->tuplehash[dir].tuple.src.u.all != | |
198 | ct->tuplehash[!dir].tuple.dst.u.all) | |
199 | ) | |
3db05fea | 200 | return ip_xfrm_me_harder(skb) == 0 ? ret : NF_DROP; |
5b1158e9 JK |
201 | } |
202 | #endif | |
203 | return ret; | |
204 | } | |
205 | ||
206 | static unsigned int | |
207 | nf_nat_local_fn(unsigned int hooknum, | |
3db05fea | 208 | struct sk_buff *skb, |
5b1158e9 JK |
209 | const struct net_device *in, |
210 | const struct net_device *out, | |
211 | int (*okfn)(struct sk_buff *)) | |
212 | { | |
72b72949 | 213 | const struct nf_conn *ct; |
5b1158e9 JK |
214 | enum ip_conntrack_info ctinfo; |
215 | unsigned int ret; | |
216 | ||
217 | /* root is playing with raw sockets. */ | |
3db05fea HX |
218 | if (skb->len < sizeof(struct iphdr) || |
219 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
220 | return NF_ACCEPT; |
221 | ||
3db05fea | 222 | ret = nf_nat_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 223 | if (ret != NF_DROP && ret != NF_STOLEN && |
3db05fea | 224 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
225 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
226 | ||
227 | if (ct->tuplehash[dir].tuple.dst.u3.ip != | |
848c29fd | 228 | ct->tuplehash[!dir].tuple.src.u3.ip) { |
3db05fea | 229 | if (ip_route_me_harder(skb, RTN_UNSPEC)) |
5b1158e9 | 230 | ret = NF_DROP; |
848c29fd PM |
231 | } |
232 | #ifdef CONFIG_XFRM | |
233 | else if (ct->tuplehash[dir].tuple.dst.u.all != | |
234 | ct->tuplehash[!dir].tuple.src.u.all) | |
3db05fea | 235 | if (ip_xfrm_me_harder(skb)) |
848c29fd PM |
236 | ret = NF_DROP; |
237 | #endif | |
5b1158e9 JK |
238 | } |
239 | return ret; | |
240 | } | |
241 | ||
5b1158e9 JK |
242 | /* We must be after connection tracking and before packet filtering. */ |
243 | ||
1999414a | 244 | static struct nf_hook_ops nf_nat_ops[] __read_mostly = { |
5b1158e9 JK |
245 | /* Before packet filtering, change destination */ |
246 | { | |
247 | .hook = nf_nat_in, | |
248 | .owner = THIS_MODULE, | |
24c232d8 | 249 | .pf = NFPROTO_IPV4, |
6e23ae2a | 250 | .hooknum = NF_INET_PRE_ROUTING, |
5b1158e9 JK |
251 | .priority = NF_IP_PRI_NAT_DST, |
252 | }, | |
253 | /* After packet filtering, change source */ | |
254 | { | |
255 | .hook = nf_nat_out, | |
256 | .owner = THIS_MODULE, | |
24c232d8 | 257 | .pf = NFPROTO_IPV4, |
6e23ae2a | 258 | .hooknum = NF_INET_POST_ROUTING, |
5b1158e9 JK |
259 | .priority = NF_IP_PRI_NAT_SRC, |
260 | }, | |
5b1158e9 JK |
261 | /* Before packet filtering, change destination */ |
262 | { | |
263 | .hook = nf_nat_local_fn, | |
264 | .owner = THIS_MODULE, | |
24c232d8 | 265 | .pf = NFPROTO_IPV4, |
6e23ae2a | 266 | .hooknum = NF_INET_LOCAL_OUT, |
5b1158e9 JK |
267 | .priority = NF_IP_PRI_NAT_DST, |
268 | }, | |
269 | /* After packet filtering, change source */ | |
270 | { | |
271 | .hook = nf_nat_fn, | |
272 | .owner = THIS_MODULE, | |
24c232d8 | 273 | .pf = NFPROTO_IPV4, |
6e23ae2a | 274 | .hooknum = NF_INET_LOCAL_IN, |
5b1158e9 JK |
275 | .priority = NF_IP_PRI_NAT_SRC, |
276 | }, | |
5b1158e9 JK |
277 | }; |
278 | ||
279 | static int __init nf_nat_standalone_init(void) | |
280 | { | |
2d59e5ca | 281 | int ret = 0; |
5b1158e9 | 282 | |
591e6206 | 283 | need_ipv4_conntrack(); |
5b1158e9 | 284 | |
5b1158e9 JK |
285 | #ifdef CONFIG_XFRM |
286 | BUG_ON(ip_nat_decode_session != NULL); | |
a9b3cd7f | 287 | RCU_INIT_POINTER(ip_nat_decode_session, nat_decode_session); |
5b1158e9 JK |
288 | #endif |
289 | ret = nf_nat_rule_init(); | |
290 | if (ret < 0) { | |
654d0fbd | 291 | pr_err("nf_nat_init: can't setup rules.\n"); |
5b1158e9 JK |
292 | goto cleanup_decode_session; |
293 | } | |
294 | ret = nf_register_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops)); | |
295 | if (ret < 0) { | |
654d0fbd | 296 | pr_err("nf_nat_init: can't register hooks.\n"); |
5b1158e9 JK |
297 | goto cleanup_rule_init; |
298 | } | |
5b1158e9 JK |
299 | return ret; |
300 | ||
301 | cleanup_rule_init: | |
302 | nf_nat_rule_cleanup(); | |
303 | cleanup_decode_session: | |
304 | #ifdef CONFIG_XFRM | |
a9b3cd7f | 305 | RCU_INIT_POINTER(ip_nat_decode_session, NULL); |
5b1158e9 JK |
306 | synchronize_net(); |
307 | #endif | |
5b1158e9 JK |
308 | return ret; |
309 | } | |
310 | ||
311 | static void __exit nf_nat_standalone_fini(void) | |
312 | { | |
313 | nf_unregister_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops)); | |
314 | nf_nat_rule_cleanup(); | |
5b1158e9 | 315 | #ifdef CONFIG_XFRM |
a9b3cd7f | 316 | RCU_INIT_POINTER(ip_nat_decode_session, NULL); |
5b1158e9 JK |
317 | synchronize_net(); |
318 | #endif | |
319 | /* Conntrack caches are unregistered in nf_conntrack_cleanup */ | |
320 | } | |
321 | ||
322 | module_init(nf_nat_standalone_init); | |
323 | module_exit(nf_nat_standalone_fini); | |
324 | ||
325 | MODULE_LICENSE("GPL"); | |
326 | MODULE_ALIAS("ip_nat"); |