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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 | { | |
72b72949 JE |
34 | const struct nf_conn *ct; |
35 | const struct nf_conntrack_tuple *t; | |
5b1158e9 JK |
36 | enum ip_conntrack_info ctinfo; |
37 | enum ip_conntrack_dir dir; | |
38 | unsigned long statusbit; | |
39 | ||
40 | ct = nf_ct_get(skb, &ctinfo); | |
41 | if (ct == NULL) | |
42 | return; | |
43 | dir = CTINFO2DIR(ctinfo); | |
44 | t = &ct->tuplehash[dir].tuple; | |
45 | ||
46 | if (dir == IP_CT_DIR_ORIGINAL) | |
47 | statusbit = IPS_DST_NAT; | |
48 | else | |
49 | statusbit = IPS_SRC_NAT; | |
50 | ||
51 | if (ct->status & statusbit) { | |
52 | fl->fl4_dst = t->dst.u3.ip; | |
53 | if (t->dst.protonum == IPPROTO_TCP || | |
6185f870 | 54 | t->dst.protonum == IPPROTO_UDP || |
4910a087 | 55 | t->dst.protonum == IPPROTO_UDPLITE || |
9d908a69 PM |
56 | t->dst.protonum == IPPROTO_DCCP || |
57 | t->dst.protonum == IPPROTO_SCTP) | |
6281dcc9 | 58 | fl->fl4_dport = t->dst.u.tcp.port; |
5b1158e9 JK |
59 | } |
60 | ||
61 | statusbit ^= IPS_NAT_MASK; | |
62 | ||
63 | if (ct->status & statusbit) { | |
64 | fl->fl4_src = t->src.u3.ip; | |
65 | if (t->dst.protonum == IPPROTO_TCP || | |
6185f870 | 66 | t->dst.protonum == IPPROTO_UDP || |
4910a087 | 67 | t->dst.protonum == IPPROTO_UDPLITE || |
9d908a69 PM |
68 | t->dst.protonum == IPPROTO_DCCP || |
69 | t->dst.protonum == IPPROTO_SCTP) | |
6281dcc9 | 70 | fl->fl4_sport = t->src.u.tcp.port; |
5b1158e9 JK |
71 | } |
72 | } | |
73 | #endif | |
74 | ||
75 | static unsigned int | |
76 | nf_nat_fn(unsigned int hooknum, | |
3db05fea | 77 | struct sk_buff *skb, |
5b1158e9 JK |
78 | const struct net_device *in, |
79 | const struct net_device *out, | |
80 | int (*okfn)(struct sk_buff *)) | |
81 | { | |
82 | struct nf_conn *ct; | |
83 | enum ip_conntrack_info ctinfo; | |
84 | struct nf_conn_nat *nat; | |
5b1158e9 JK |
85 | /* maniptype == SRC for postrouting. */ |
86 | enum nf_nat_manip_type maniptype = HOOK2MANIP(hooknum); | |
87 | ||
88 | /* We never see fragments: conntrack defrags on pre-routing | |
89 | and local-out, and nf_nat_out protects post-routing. */ | |
3db05fea | 90 | NF_CT_ASSERT(!(ip_hdr(skb)->frag_off & htons(IP_MF | IP_OFFSET))); |
5b1158e9 | 91 | |
3db05fea | 92 | ct = nf_ct_get(skb, &ctinfo); |
5b1158e9 JK |
93 | /* Can't track? It's not due to stress, or conntrack would |
94 | have dropped it. Hence it's the user's responsibilty to | |
95 | packet filter it out, or implement conntrack/NAT for that | |
96 | protocol. 8) --RR */ | |
42cf800c | 97 | if (!ct) |
5b1158e9 | 98 | return NF_ACCEPT; |
5b1158e9 JK |
99 | |
100 | /* Don't try to NAT if this packet is not conntracked */ | |
5bfddbd4 | 101 | if (nf_ct_is_untracked(ct)) |
5b1158e9 JK |
102 | return NF_ACCEPT; |
103 | ||
104 | nat = nfct_nat(ct); | |
2d59e5ca | 105 | if (!nat) { |
8c87238b PM |
106 | /* NAT module was loaded late. */ |
107 | if (nf_ct_is_confirmed(ct)) | |
108 | return NF_ACCEPT; | |
2d59e5ca YK |
109 | nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC); |
110 | if (nat == NULL) { | |
0d53778e | 111 | pr_debug("failed to add NAT extension\n"); |
2d59e5ca YK |
112 | return NF_ACCEPT; |
113 | } | |
114 | } | |
5b1158e9 JK |
115 | |
116 | switch (ctinfo) { | |
117 | case IP_CT_RELATED: | |
118 | case IP_CT_RELATED+IP_CT_IS_REPLY: | |
3db05fea | 119 | if (ip_hdr(skb)->protocol == IPPROTO_ICMP) { |
5b1158e9 | 120 | if (!nf_nat_icmp_reply_translation(ct, ctinfo, |
3db05fea | 121 | hooknum, skb)) |
5b1158e9 JK |
122 | return NF_DROP; |
123 | else | |
124 | return NF_ACCEPT; | |
125 | } | |
126 | /* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */ | |
127 | case IP_CT_NEW: | |
5b1158e9 JK |
128 | |
129 | /* Seen it before? This can happen for loopback, retrans, | |
130 | or local packets.. */ | |
131 | if (!nf_nat_initialized(ct, maniptype)) { | |
132 | unsigned int ret; | |
133 | ||
c68cd6cc | 134 | ret = nf_nat_rule_find(skb, hooknum, in, out, ct); |
22068311 | 135 | if (ret != NF_ACCEPT) |
5b1158e9 | 136 | return ret; |
5b1158e9 | 137 | } else |
0d53778e PM |
138 | pr_debug("Already setup manip %s for ct %p\n", |
139 | maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST", | |
140 | ct); | |
5b1158e9 JK |
141 | break; |
142 | ||
143 | default: | |
144 | /* ESTABLISHED */ | |
145 | NF_CT_ASSERT(ctinfo == IP_CT_ESTABLISHED || | |
146 | ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY)); | |
5b1158e9 JK |
147 | } |
148 | ||
3db05fea | 149 | return nf_nat_packet(ct, ctinfo, hooknum, skb); |
5b1158e9 JK |
150 | } |
151 | ||
152 | static unsigned int | |
153 | nf_nat_in(unsigned int hooknum, | |
3db05fea | 154 | struct sk_buff *skb, |
e905a9ed YH |
155 | const struct net_device *in, |
156 | const struct net_device *out, | |
157 | int (*okfn)(struct sk_buff *)) | |
5b1158e9 JK |
158 | { |
159 | unsigned int ret; | |
3db05fea | 160 | __be32 daddr = ip_hdr(skb)->daddr; |
5b1158e9 | 161 | |
3db05fea | 162 | ret = nf_nat_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 163 | if (ret != NF_DROP && ret != NF_STOLEN && |
adf30907 ED |
164 | daddr != ip_hdr(skb)->daddr) |
165 | skb_dst_drop(skb); | |
166 | ||
5b1158e9 JK |
167 | return ret; |
168 | } | |
169 | ||
170 | static unsigned int | |
171 | nf_nat_out(unsigned int hooknum, | |
3db05fea | 172 | struct sk_buff *skb, |
5b1158e9 JK |
173 | const struct net_device *in, |
174 | const struct net_device *out, | |
175 | int (*okfn)(struct sk_buff *)) | |
176 | { | |
177 | #ifdef CONFIG_XFRM | |
72b72949 | 178 | const struct nf_conn *ct; |
5b1158e9 JK |
179 | enum ip_conntrack_info ctinfo; |
180 | #endif | |
181 | unsigned int ret; | |
182 | ||
183 | /* root is playing with raw sockets. */ | |
3db05fea HX |
184 | if (skb->len < sizeof(struct iphdr) || |
185 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
186 | return NF_ACCEPT; |
187 | ||
3db05fea | 188 | ret = nf_nat_fn(hooknum, skb, in, out, okfn); |
5b1158e9 JK |
189 | #ifdef CONFIG_XFRM |
190 | if (ret != NF_DROP && ret != NF_STOLEN && | |
3db05fea | 191 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
192 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
193 | ||
3666ed1c JP |
194 | if ((ct->tuplehash[dir].tuple.src.u3.ip != |
195 | ct->tuplehash[!dir].tuple.dst.u3.ip) || | |
196 | (ct->tuplehash[dir].tuple.src.u.all != | |
197 | ct->tuplehash[!dir].tuple.dst.u.all) | |
198 | ) | |
3db05fea | 199 | return ip_xfrm_me_harder(skb) == 0 ? ret : NF_DROP; |
5b1158e9 JK |
200 | } |
201 | #endif | |
202 | return ret; | |
203 | } | |
204 | ||
205 | static unsigned int | |
206 | nf_nat_local_fn(unsigned int hooknum, | |
3db05fea | 207 | struct sk_buff *skb, |
5b1158e9 JK |
208 | const struct net_device *in, |
209 | const struct net_device *out, | |
210 | int (*okfn)(struct sk_buff *)) | |
211 | { | |
72b72949 | 212 | const struct nf_conn *ct; |
5b1158e9 JK |
213 | enum ip_conntrack_info ctinfo; |
214 | unsigned int ret; | |
215 | ||
216 | /* root is playing with raw sockets. */ | |
3db05fea HX |
217 | if (skb->len < sizeof(struct iphdr) || |
218 | ip_hdrlen(skb) < sizeof(struct iphdr)) | |
5b1158e9 JK |
219 | return NF_ACCEPT; |
220 | ||
3db05fea | 221 | ret = nf_nat_fn(hooknum, skb, in, out, okfn); |
5b1158e9 | 222 | if (ret != NF_DROP && ret != NF_STOLEN && |
3db05fea | 223 | (ct = nf_ct_get(skb, &ctinfo)) != NULL) { |
5b1158e9 JK |
224 | enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo); |
225 | ||
226 | if (ct->tuplehash[dir].tuple.dst.u3.ip != | |
848c29fd | 227 | ct->tuplehash[!dir].tuple.src.u3.ip) { |
3db05fea | 228 | if (ip_route_me_harder(skb, RTN_UNSPEC)) |
5b1158e9 | 229 | ret = NF_DROP; |
848c29fd PM |
230 | } |
231 | #ifdef CONFIG_XFRM | |
232 | else if (ct->tuplehash[dir].tuple.dst.u.all != | |
233 | ct->tuplehash[!dir].tuple.src.u.all) | |
3db05fea | 234 | if (ip_xfrm_me_harder(skb)) |
848c29fd PM |
235 | ret = NF_DROP; |
236 | #endif | |
5b1158e9 JK |
237 | } |
238 | return ret; | |
239 | } | |
240 | ||
5b1158e9 JK |
241 | /* We must be after connection tracking and before packet filtering. */ |
242 | ||
1999414a | 243 | static struct nf_hook_ops nf_nat_ops[] __read_mostly = { |
5b1158e9 JK |
244 | /* Before packet filtering, change destination */ |
245 | { | |
246 | .hook = nf_nat_in, | |
247 | .owner = THIS_MODULE, | |
24c232d8 | 248 | .pf = NFPROTO_IPV4, |
6e23ae2a | 249 | .hooknum = NF_INET_PRE_ROUTING, |
5b1158e9 JK |
250 | .priority = NF_IP_PRI_NAT_DST, |
251 | }, | |
252 | /* After packet filtering, change source */ | |
253 | { | |
254 | .hook = nf_nat_out, | |
255 | .owner = THIS_MODULE, | |
24c232d8 | 256 | .pf = NFPROTO_IPV4, |
6e23ae2a | 257 | .hooknum = NF_INET_POST_ROUTING, |
5b1158e9 JK |
258 | .priority = NF_IP_PRI_NAT_SRC, |
259 | }, | |
5b1158e9 JK |
260 | /* Before packet filtering, change destination */ |
261 | { | |
262 | .hook = nf_nat_local_fn, | |
263 | .owner = THIS_MODULE, | |
24c232d8 | 264 | .pf = NFPROTO_IPV4, |
6e23ae2a | 265 | .hooknum = NF_INET_LOCAL_OUT, |
5b1158e9 JK |
266 | .priority = NF_IP_PRI_NAT_DST, |
267 | }, | |
268 | /* After packet filtering, change source */ | |
269 | { | |
270 | .hook = nf_nat_fn, | |
271 | .owner = THIS_MODULE, | |
24c232d8 | 272 | .pf = NFPROTO_IPV4, |
6e23ae2a | 273 | .hooknum = NF_INET_LOCAL_IN, |
5b1158e9 JK |
274 | .priority = NF_IP_PRI_NAT_SRC, |
275 | }, | |
5b1158e9 JK |
276 | }; |
277 | ||
278 | static int __init nf_nat_standalone_init(void) | |
279 | { | |
2d59e5ca | 280 | int ret = 0; |
5b1158e9 | 281 | |
591e6206 | 282 | need_ipv4_conntrack(); |
5b1158e9 | 283 | |
5b1158e9 JK |
284 | #ifdef CONFIG_XFRM |
285 | BUG_ON(ip_nat_decode_session != NULL); | |
051578cc | 286 | rcu_assign_pointer(ip_nat_decode_session, nat_decode_session); |
5b1158e9 JK |
287 | #endif |
288 | ret = nf_nat_rule_init(); | |
289 | if (ret < 0) { | |
654d0fbd | 290 | pr_err("nf_nat_init: can't setup rules.\n"); |
5b1158e9 JK |
291 | goto cleanup_decode_session; |
292 | } | |
293 | ret = nf_register_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops)); | |
294 | if (ret < 0) { | |
654d0fbd | 295 | pr_err("nf_nat_init: can't register hooks.\n"); |
5b1158e9 JK |
296 | goto cleanup_rule_init; |
297 | } | |
5b1158e9 JK |
298 | return ret; |
299 | ||
300 | cleanup_rule_init: | |
301 | nf_nat_rule_cleanup(); | |
302 | cleanup_decode_session: | |
303 | #ifdef CONFIG_XFRM | |
051578cc | 304 | rcu_assign_pointer(ip_nat_decode_session, NULL); |
5b1158e9 JK |
305 | synchronize_net(); |
306 | #endif | |
5b1158e9 JK |
307 | return ret; |
308 | } | |
309 | ||
310 | static void __exit nf_nat_standalone_fini(void) | |
311 | { | |
312 | nf_unregister_hooks(nf_nat_ops, ARRAY_SIZE(nf_nat_ops)); | |
313 | nf_nat_rule_cleanup(); | |
5b1158e9 | 314 | #ifdef CONFIG_XFRM |
051578cc | 315 | rcu_assign_pointer(ip_nat_decode_session, NULL); |
5b1158e9 JK |
316 | synchronize_net(); |
317 | #endif | |
318 | /* Conntrack caches are unregistered in nf_conntrack_cleanup */ | |
319 | } | |
320 | ||
321 | module_init(nf_nat_standalone_init); | |
322 | module_exit(nf_nat_standalone_fini); | |
323 | ||
324 | MODULE_LICENSE("GPL"); | |
325 | MODULE_ALIAS("ip_nat"); |