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Herbert Xub4219952007-09-27 12:48:05 -07001/*
2 * Stateless NAT actions
3 *
4 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the Free
8 * Software Foundation; either version 2 of the License, or (at your option)
9 * any later version.
10 */
11
12#include <linux/errno.h>
13#include <linux/init.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/netfilter.h>
17#include <linux/rtnetlink.h>
18#include <linux/skbuff.h>
19#include <linux/slab.h>
20#include <linux/spinlock.h>
21#include <linux/string.h>
22#include <linux/tc_act/tc_nat.h>
23#include <net/act_api.h>
24#include <net/icmp.h>
25#include <net/ip.h>
26#include <net/netlink.h>
27#include <net/tc_act/tc_nat.h>
28#include <net/tcp.h>
29#include <net/udp.h>
30
31
32#define NAT_TAB_MASK 15
33static struct tcf_common *tcf_nat_ht[NAT_TAB_MASK + 1];
34static u32 nat_idx_gen;
35static DEFINE_RWLOCK(nat_lock);
36
37static struct tcf_hashinfo nat_hash_info = {
38 .htab = tcf_nat_ht,
39 .hmask = NAT_TAB_MASK,
40 .lock = &nat_lock,
41};
42
Patrick McHardy53b2bf32008-01-23 20:36:30 -080043static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
44 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
45};
46
Patrick McHardy7ba699c2008-01-22 22:11:50 -080047static int tcf_nat_init(struct nlattr *nla, struct nlattr *est,
Herbert Xub4219952007-09-27 12:48:05 -070048 struct tc_action *a, int ovr, int bind)
49{
Patrick McHardy7ba699c2008-01-22 22:11:50 -080050 struct nlattr *tb[TCA_NAT_MAX + 1];
Herbert Xub4219952007-09-27 12:48:05 -070051 struct tc_nat *parm;
Patrick McHardycee63722008-01-23 20:33:32 -080052 int ret = 0, err;
Herbert Xub4219952007-09-27 12:48:05 -070053 struct tcf_nat *p;
54 struct tcf_common *pc;
55
Patrick McHardycee63722008-01-23 20:33:32 -080056 if (nla == NULL)
Herbert Xub4219952007-09-27 12:48:05 -070057 return -EINVAL;
58
Patrick McHardy53b2bf32008-01-23 20:36:30 -080059 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
Patrick McHardycee63722008-01-23 20:33:32 -080060 if (err < 0)
61 return err;
62
Patrick McHardy53b2bf32008-01-23 20:36:30 -080063 if (tb[TCA_NAT_PARMS] == NULL)
Herbert Xub4219952007-09-27 12:48:05 -070064 return -EINVAL;
Patrick McHardy7ba699c2008-01-22 22:11:50 -080065 parm = nla_data(tb[TCA_NAT_PARMS]);
Herbert Xub4219952007-09-27 12:48:05 -070066
67 pc = tcf_hash_check(parm->index, a, bind, &nat_hash_info);
68 if (!pc) {
69 pc = tcf_hash_create(parm->index, est, a, sizeof(*p), bind,
70 &nat_idx_gen, &nat_hash_info);
Stephen Hemminger0e991ec2008-11-25 21:12:32 -080071 if (IS_ERR(pc))
Eric Dumazetcc7ec452011-01-19 19:26:56 +000072 return PTR_ERR(pc);
Herbert Xub4219952007-09-27 12:48:05 -070073 p = to_tcf_nat(pc);
74 ret = ACT_P_CREATED;
75 } else {
76 p = to_tcf_nat(pc);
77 if (!ovr) {
78 tcf_hash_release(pc, bind, &nat_hash_info);
79 return -EEXIST;
80 }
81 }
82
83 spin_lock_bh(&p->tcf_lock);
84 p->old_addr = parm->old_addr;
85 p->new_addr = parm->new_addr;
86 p->mask = parm->mask;
87 p->flags = parm->flags;
88
89 p->tcf_action = parm->action;
90 spin_unlock_bh(&p->tcf_lock);
91
92 if (ret == ACT_P_CREATED)
93 tcf_hash_insert(pc, &nat_hash_info);
94
95 return ret;
96}
97
98static int tcf_nat_cleanup(struct tc_action *a, int bind)
99{
100 struct tcf_nat *p = a->priv;
101
102 return tcf_hash_release(&p->common, bind, &nat_hash_info);
103}
104
Eric Dumazetdc7f9f62011-07-05 23:25:42 +0000105static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
Herbert Xub4219952007-09-27 12:48:05 -0700106 struct tcf_result *res)
107{
108 struct tcf_nat *p = a->priv;
109 struct iphdr *iph;
110 __be32 old_addr;
111 __be32 new_addr;
112 __be32 mask;
113 __be32 addr;
114 int egress;
115 int action;
116 int ihl;
Changli Gao36d12692010-08-03 17:39:18 +0000117 int noff;
Herbert Xub4219952007-09-27 12:48:05 -0700118
119 spin_lock(&p->tcf_lock);
120
121 p->tcf_tm.lastuse = jiffies;
122 old_addr = p->old_addr;
123 new_addr = p->new_addr;
124 mask = p->mask;
125 egress = p->flags & TCA_NAT_FLAG_EGRESS;
126 action = p->tcf_action;
127
Eric Dumazetbfe0d022011-01-09 08:30:54 +0000128 bstats_update(&p->tcf_bstats, skb);
Herbert Xub4219952007-09-27 12:48:05 -0700129
130 spin_unlock(&p->tcf_lock);
131
132 if (unlikely(action == TC_ACT_SHOT))
133 goto drop;
134
Changli Gao36d12692010-08-03 17:39:18 +0000135 noff = skb_network_offset(skb);
136 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700137 goto drop;
138
139 iph = ip_hdr(skb);
140
141 if (egress)
142 addr = iph->saddr;
143 else
144 addr = iph->daddr;
145
146 if (!((old_addr ^ addr) & mask)) {
147 if (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000148 !skb_clone_writable(skb, sizeof(*iph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700149 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
150 goto drop;
151
152 new_addr &= mask;
153 new_addr |= addr & ~mask;
154
155 /* Rewrite IP header */
156 iph = ip_hdr(skb);
157 if (egress)
158 iph->saddr = new_addr;
159 else
160 iph->daddr = new_addr;
161
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100162 csum_replace4(&iph->check, addr, new_addr);
Changli Gao33c29dd2010-05-29 14:26:59 +0000163 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
164 iph->protocol != IPPROTO_ICMP) {
165 goto out;
Herbert Xub4219952007-09-27 12:48:05 -0700166 }
167
168 ihl = iph->ihl * 4;
169
170 /* It would be nice to share code with stateful NAT. */
171 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
172 case IPPROTO_TCP:
173 {
174 struct tcphdr *tcph;
175
Changli Gao36d12692010-08-03 17:39:18 +0000176 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
Herbert Xub4219952007-09-27 12:48:05 -0700177 (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000178 !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700179 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
180 goto drop;
181
182 tcph = (void *)(skb_network_header(skb) + ihl);
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100183 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr, 1);
Herbert Xub4219952007-09-27 12:48:05 -0700184 break;
185 }
186 case IPPROTO_UDP:
187 {
188 struct udphdr *udph;
189
Changli Gao36d12692010-08-03 17:39:18 +0000190 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
Herbert Xub4219952007-09-27 12:48:05 -0700191 (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000192 !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700193 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
194 goto drop;
195
196 udph = (void *)(skb_network_header(skb) + ihl);
197 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100198 inet_proto_csum_replace4(&udph->check, skb, addr,
199 new_addr, 1);
Herbert Xub4219952007-09-27 12:48:05 -0700200 if (!udph->check)
201 udph->check = CSUM_MANGLED_0;
202 }
203 break;
204 }
205 case IPPROTO_ICMP:
206 {
207 struct icmphdr *icmph;
208
Changli Gao36d12692010-08-03 17:39:18 +0000209 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700210 goto drop;
211
212 icmph = (void *)(skb_network_header(skb) + ihl);
213
214 if ((icmph->type != ICMP_DEST_UNREACH) &&
215 (icmph->type != ICMP_TIME_EXCEEDED) &&
216 (icmph->type != ICMP_PARAMETERPROB))
217 break;
218
Changli Gao36d12692010-08-03 17:39:18 +0000219 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
220 noff))
Changli Gao70c2efa2010-07-09 15:33:25 +0000221 goto drop;
222
Changli Gao072d79a2010-07-29 13:41:46 +0000223 icmph = (void *)(skb_network_header(skb) + ihl);
Herbert Xub4219952007-09-27 12:48:05 -0700224 iph = (void *)(icmph + 1);
225 if (egress)
226 addr = iph->daddr;
227 else
228 addr = iph->saddr;
229
230 if ((old_addr ^ addr) & mask)
231 break;
232
233 if (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000234 !skb_clone_writable(skb, ihl + sizeof(*icmph) +
235 sizeof(*iph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700236 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
237 goto drop;
238
239 icmph = (void *)(skb_network_header(skb) + ihl);
240 iph = (void *)(icmph + 1);
241
242 new_addr &= mask;
243 new_addr |= addr & ~mask;
244
245 /* XXX Fix up the inner checksums. */
246 if (egress)
247 iph->daddr = new_addr;
248 else
249 iph->saddr = new_addr;
250
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100251 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
Changli Gao3a3dfb02010-07-29 14:04:18 +0000252 0);
Herbert Xub4219952007-09-27 12:48:05 -0700253 break;
254 }
255 default:
256 break;
257 }
258
Changli Gao33c29dd2010-05-29 14:26:59 +0000259out:
Herbert Xub4219952007-09-27 12:48:05 -0700260 return action;
261
262drop:
263 spin_lock(&p->tcf_lock);
264 p->tcf_qstats.drops++;
265 spin_unlock(&p->tcf_lock);
266 return TC_ACT_SHOT;
267}
268
269static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
270 int bind, int ref)
271{
272 unsigned char *b = skb_tail_pointer(skb);
273 struct tcf_nat *p = a->priv;
Eric Dumazet1c40be12010-08-16 20:04:22 +0000274 struct tc_nat opt = {
275 .old_addr = p->old_addr,
276 .new_addr = p->new_addr,
277 .mask = p->mask,
278 .flags = p->flags,
279
280 .index = p->tcf_index,
281 .action = p->tcf_action,
282 .refcnt = p->tcf_refcnt - ref,
283 .bindcnt = p->tcf_bindcnt - bind,
284 };
Herbert Xub4219952007-09-27 12:48:05 -0700285 struct tcf_t t;
Herbert Xub4219952007-09-27 12:48:05 -0700286
David S. Miller1b34ec42012-03-29 05:11:39 -0400287 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
288 goto nla_put_failure;
Herbert Xub4219952007-09-27 12:48:05 -0700289 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
290 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
291 t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
David S. Miller1b34ec42012-03-29 05:11:39 -0400292 if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t))
293 goto nla_put_failure;
Herbert Xub4219952007-09-27 12:48:05 -0700294
Herbert Xub4219952007-09-27 12:48:05 -0700295 return skb->len;
296
Patrick McHardy7ba699c2008-01-22 22:11:50 -0800297nla_put_failure:
Herbert Xub4219952007-09-27 12:48:05 -0700298 nlmsg_trim(skb, b);
Herbert Xub4219952007-09-27 12:48:05 -0700299 return -1;
300}
301
302static struct tc_action_ops act_nat_ops = {
303 .kind = "nat",
304 .hinfo = &nat_hash_info,
305 .type = TCA_ACT_NAT,
306 .capab = TCA_CAP_NONE,
307 .owner = THIS_MODULE,
308 .act = tcf_nat,
309 .dump = tcf_nat_dump,
310 .cleanup = tcf_nat_cleanup,
311 .lookup = tcf_hash_search,
312 .init = tcf_nat_init,
313 .walk = tcf_generic_walker
314};
315
316MODULE_DESCRIPTION("Stateless NAT actions");
317MODULE_LICENSE("GPL");
318
319static int __init nat_init_module(void)
320{
321 return tcf_register_action(&act_nat_ops);
322}
323
324static void __exit nat_cleanup_module(void)
325{
326 tcf_unregister_action(&act_nat_ops);
327}
328
329module_init(nat_init_module);
330module_exit(nat_cleanup_module);