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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
Herbert Xub4219952007-09-27 12:48:05 -070033
Patrick McHardy53b2bf32008-01-23 20:36:30 -080034static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
35 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
36};
37
Benjamin LaHaisec1b52732013-01-14 05:15:39 +000038static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
Herbert Xub4219952007-09-27 12:48:05 -070039 struct tc_action *a, int ovr, int bind)
40{
Patrick McHardy7ba699c2008-01-22 22:11:50 -080041 struct nlattr *tb[TCA_NAT_MAX + 1];
Herbert Xub4219952007-09-27 12:48:05 -070042 struct tc_nat *parm;
Patrick McHardycee63722008-01-23 20:33:32 -080043 int ret = 0, err;
Herbert Xub4219952007-09-27 12:48:05 -070044 struct tcf_nat *p;
Herbert Xub4219952007-09-27 12:48:05 -070045
Patrick McHardycee63722008-01-23 20:33:32 -080046 if (nla == NULL)
Herbert Xub4219952007-09-27 12:48:05 -070047 return -EINVAL;
48
Patrick McHardy53b2bf32008-01-23 20:36:30 -080049 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
Patrick McHardycee63722008-01-23 20:33:32 -080050 if (err < 0)
51 return err;
52
Patrick McHardy53b2bf32008-01-23 20:36:30 -080053 if (tb[TCA_NAT_PARMS] == NULL)
Herbert Xub4219952007-09-27 12:48:05 -070054 return -EINVAL;
Patrick McHardy7ba699c2008-01-22 22:11:50 -080055 parm = nla_data(tb[TCA_NAT_PARMS]);
Herbert Xub4219952007-09-27 12:48:05 -070056
WANG Cong86062032014-02-11 17:07:31 -080057 if (!tcf_hash_check(parm->index, a, bind)) {
Eric Dumazet519c8182015-07-06 05:18:04 -070058 ret = tcf_hash_create(parm->index, est, a, sizeof(*p),
59 bind, false);
WANG Cong86062032014-02-11 17:07:31 -080060 if (ret)
61 return ret;
Herbert Xub4219952007-09-27 12:48:05 -070062 ret = ACT_P_CREATED;
63 } else {
Jamal Hadi Salim1a293212013-12-23 08:02:11 -050064 if (bind)
65 return 0;
WANG Cong86062032014-02-11 17:07:31 -080066 tcf_hash_release(a, bind);
Jamal Hadi Salim1a293212013-12-23 08:02:11 -050067 if (!ovr)
Herbert Xub4219952007-09-27 12:48:05 -070068 return -EEXIST;
Herbert Xub4219952007-09-27 12:48:05 -070069 }
WANG Cong86062032014-02-11 17:07:31 -080070 p = to_tcf_nat(a);
Herbert Xub4219952007-09-27 12:48:05 -070071
72 spin_lock_bh(&p->tcf_lock);
73 p->old_addr = parm->old_addr;
74 p->new_addr = parm->new_addr;
75 p->mask = parm->mask;
76 p->flags = parm->flags;
77
78 p->tcf_action = parm->action;
79 spin_unlock_bh(&p->tcf_lock);
80
81 if (ret == ACT_P_CREATED)
WANG Cong86062032014-02-11 17:07:31 -080082 tcf_hash_insert(a);
Herbert Xub4219952007-09-27 12:48:05 -070083
84 return ret;
85}
86
Eric Dumazetdc7f9f62011-07-05 23:25:42 +000087static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
Herbert Xub4219952007-09-27 12:48:05 -070088 struct tcf_result *res)
89{
90 struct tcf_nat *p = a->priv;
91 struct iphdr *iph;
92 __be32 old_addr;
93 __be32 new_addr;
94 __be32 mask;
95 __be32 addr;
96 int egress;
97 int action;
98 int ihl;
Changli Gao36d12692010-08-03 17:39:18 +000099 int noff;
Herbert Xub4219952007-09-27 12:48:05 -0700100
101 spin_lock(&p->tcf_lock);
102
103 p->tcf_tm.lastuse = jiffies;
104 old_addr = p->old_addr;
105 new_addr = p->new_addr;
106 mask = p->mask;
107 egress = p->flags & TCA_NAT_FLAG_EGRESS;
108 action = p->tcf_action;
109
Eric Dumazetbfe0d022011-01-09 08:30:54 +0000110 bstats_update(&p->tcf_bstats, skb);
Herbert Xub4219952007-09-27 12:48:05 -0700111
112 spin_unlock(&p->tcf_lock);
113
114 if (unlikely(action == TC_ACT_SHOT))
115 goto drop;
116
Changli Gao36d12692010-08-03 17:39:18 +0000117 noff = skb_network_offset(skb);
118 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700119 goto drop;
120
121 iph = ip_hdr(skb);
122
123 if (egress)
124 addr = iph->saddr;
125 else
126 addr = iph->daddr;
127
128 if (!((old_addr ^ addr) & mask)) {
129 if (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000130 !skb_clone_writable(skb, sizeof(*iph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700131 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
132 goto drop;
133
134 new_addr &= mask;
135 new_addr |= addr & ~mask;
136
137 /* Rewrite IP header */
138 iph = ip_hdr(skb);
139 if (egress)
140 iph->saddr = new_addr;
141 else
142 iph->daddr = new_addr;
143
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100144 csum_replace4(&iph->check, addr, new_addr);
Changli Gao33c29dd2010-05-29 14:26:59 +0000145 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
146 iph->protocol != IPPROTO_ICMP) {
147 goto out;
Herbert Xub4219952007-09-27 12:48:05 -0700148 }
149
150 ihl = iph->ihl * 4;
151
152 /* It would be nice to share code with stateful NAT. */
153 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
154 case IPPROTO_TCP:
155 {
156 struct tcphdr *tcph;
157
Changli Gao36d12692010-08-03 17:39:18 +0000158 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
Herbert Xub4219952007-09-27 12:48:05 -0700159 (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000160 !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700161 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
162 goto drop;
163
164 tcph = (void *)(skb_network_header(skb) + ihl);
Tom Herbert4b048d62015-08-17 13:42:25 -0700165 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
166 true);
Herbert Xub4219952007-09-27 12:48:05 -0700167 break;
168 }
169 case IPPROTO_UDP:
170 {
171 struct udphdr *udph;
172
Changli Gao36d12692010-08-03 17:39:18 +0000173 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
Herbert Xub4219952007-09-27 12:48:05 -0700174 (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000175 !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700176 pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
177 goto drop;
178
179 udph = (void *)(skb_network_header(skb) + ihl);
180 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100181 inet_proto_csum_replace4(&udph->check, skb, addr,
Tom Herbert4b048d62015-08-17 13:42:25 -0700182 new_addr, true);
Herbert Xub4219952007-09-27 12:48:05 -0700183 if (!udph->check)
184 udph->check = CSUM_MANGLED_0;
185 }
186 break;
187 }
188 case IPPROTO_ICMP:
189 {
190 struct icmphdr *icmph;
191
Changli Gao36d12692010-08-03 17:39:18 +0000192 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700193 goto drop;
194
195 icmph = (void *)(skb_network_header(skb) + ihl);
196
197 if ((icmph->type != ICMP_DEST_UNREACH) &&
198 (icmph->type != ICMP_TIME_EXCEEDED) &&
199 (icmph->type != ICMP_PARAMETERPROB))
200 break;
201
Changli Gao36d12692010-08-03 17:39:18 +0000202 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
203 noff))
Changli Gao70c2efa2010-07-09 15:33:25 +0000204 goto drop;
205
Changli Gao072d79a2010-07-29 13:41:46 +0000206 icmph = (void *)(skb_network_header(skb) + ihl);
Herbert Xub4219952007-09-27 12:48:05 -0700207 iph = (void *)(icmph + 1);
208 if (egress)
209 addr = iph->daddr;
210 else
211 addr = iph->saddr;
212
213 if ((old_addr ^ addr) & mask)
214 break;
215
216 if (skb_cloned(skb) &&
Changli Gao36d12692010-08-03 17:39:18 +0000217 !skb_clone_writable(skb, ihl + sizeof(*icmph) +
218 sizeof(*iph) + noff) &&
Herbert Xub4219952007-09-27 12:48:05 -0700219 pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
220 goto drop;
221
222 icmph = (void *)(skb_network_header(skb) + ihl);
223 iph = (void *)(icmph + 1);
224
225 new_addr &= mask;
226 new_addr |= addr & ~mask;
227
228 /* XXX Fix up the inner checksums. */
229 if (egress)
230 iph->daddr = new_addr;
231 else
232 iph->saddr = new_addr;
233
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100234 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
Tom Herbert4b048d62015-08-17 13:42:25 -0700235 false);
Herbert Xub4219952007-09-27 12:48:05 -0700236 break;
237 }
238 default:
239 break;
240 }
241
Changli Gao33c29dd2010-05-29 14:26:59 +0000242out:
Herbert Xub4219952007-09-27 12:48:05 -0700243 return action;
244
245drop:
246 spin_lock(&p->tcf_lock);
247 p->tcf_qstats.drops++;
248 spin_unlock(&p->tcf_lock);
249 return TC_ACT_SHOT;
250}
251
252static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
253 int bind, int ref)
254{
255 unsigned char *b = skb_tail_pointer(skb);
256 struct tcf_nat *p = a->priv;
Eric Dumazet1c40be12010-08-16 20:04:22 +0000257 struct tc_nat opt = {
258 .old_addr = p->old_addr,
259 .new_addr = p->new_addr,
260 .mask = p->mask,
261 .flags = p->flags,
262
263 .index = p->tcf_index,
264 .action = p->tcf_action,
265 .refcnt = p->tcf_refcnt - ref,
266 .bindcnt = p->tcf_bindcnt - bind,
267 };
Herbert Xub4219952007-09-27 12:48:05 -0700268 struct tcf_t t;
Herbert Xub4219952007-09-27 12:48:05 -0700269
David S. Miller1b34ec42012-03-29 05:11:39 -0400270 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
271 goto nla_put_failure;
Herbert Xub4219952007-09-27 12:48:05 -0700272 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
273 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
274 t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
David S. Miller1b34ec42012-03-29 05:11:39 -0400275 if (nla_put(skb, TCA_NAT_TM, sizeof(t), &t))
276 goto nla_put_failure;
Herbert Xub4219952007-09-27 12:48:05 -0700277
Herbert Xub4219952007-09-27 12:48:05 -0700278 return skb->len;
279
Patrick McHardy7ba699c2008-01-22 22:11:50 -0800280nla_put_failure:
Herbert Xub4219952007-09-27 12:48:05 -0700281 nlmsg_trim(skb, b);
Herbert Xub4219952007-09-27 12:48:05 -0700282 return -1;
283}
284
285static struct tc_action_ops act_nat_ops = {
286 .kind = "nat",
Herbert Xub4219952007-09-27 12:48:05 -0700287 .type = TCA_ACT_NAT,
Herbert Xub4219952007-09-27 12:48:05 -0700288 .owner = THIS_MODULE,
289 .act = tcf_nat,
290 .dump = tcf_nat_dump,
Herbert Xub4219952007-09-27 12:48:05 -0700291 .init = tcf_nat_init,
Herbert Xub4219952007-09-27 12:48:05 -0700292};
293
294MODULE_DESCRIPTION("Stateless NAT actions");
295MODULE_LICENSE("GPL");
296
297static int __init nat_init_module(void)
298{
WANG Cong4f1e9d82014-02-11 17:07:33 -0800299 return tcf_register_action(&act_nat_ops, NAT_TAB_MASK);
Herbert Xub4219952007-09-27 12:48:05 -0700300}
301
302static void __exit nat_cleanup_module(void)
303{
304 tcf_unregister_action(&act_nat_ops);
Herbert Xub4219952007-09-27 12:48:05 -0700305}
306
307module_init(nat_init_module);
308module_exit(nat_cleanup_module);