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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
Alexey Dobriyanc7d03a02016-11-17 04:58:21 +030032static unsigned int nat_net_id;
WANG Conga85a9702016-07-25 16:09:41 -070033static struct tc_action_ops act_nat_ops;
WANG Congddf97cc2016-02-22 15:57:53 -080034
Patrick McHardy53b2bf32008-01-23 20:36:30 -080035static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
36 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
37};
38
Benjamin LaHaisec1b52732013-01-14 05:15:39 +000039static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
Alexander Aring589dad62018-02-15 10:54:56 -050040 struct tc_action **a, int ovr, int bind,
41 struct netlink_ext_ack *extack)
Herbert Xub4219952007-09-27 12:48:05 -070042{
WANG Congddf97cc2016-02-22 15:57:53 -080043 struct tc_action_net *tn = net_generic(net, nat_net_id);
Patrick McHardy7ba699c2008-01-22 22:11:50 -080044 struct nlattr *tb[TCA_NAT_MAX + 1];
Herbert Xub4219952007-09-27 12:48:05 -070045 struct tc_nat *parm;
Patrick McHardycee63722008-01-23 20:33:32 -080046 int ret = 0, err;
Herbert Xub4219952007-09-27 12:48:05 -070047 struct tcf_nat *p;
Herbert Xub4219952007-09-27 12:48:05 -070048
Patrick McHardycee63722008-01-23 20:33:32 -080049 if (nla == NULL)
Herbert Xub4219952007-09-27 12:48:05 -070050 return -EINVAL;
51
Johannes Bergfceb6432017-04-12 14:34:07 +020052 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy, NULL);
Patrick McHardycee63722008-01-23 20:33:32 -080053 if (err < 0)
54 return err;
55
Patrick McHardy53b2bf32008-01-23 20:36:30 -080056 if (tb[TCA_NAT_PARMS] == NULL)
Herbert Xub4219952007-09-27 12:48:05 -070057 return -EINVAL;
Patrick McHardy7ba699c2008-01-22 22:11:50 -080058 parm = nla_data(tb[TCA_NAT_PARMS]);
Herbert Xub4219952007-09-27 12:48:05 -070059
Chris Mi65a206c2017-08-30 02:31:59 -040060 if (!tcf_idr_check(tn, parm->index, a, bind)) {
61 ret = tcf_idr_create(tn, parm->index, est, a,
62 &act_nat_ops, bind, false);
WANG Cong86062032014-02-11 17:07:31 -080063 if (ret)
64 return ret;
Herbert Xub4219952007-09-27 12:48:05 -070065 ret = ACT_P_CREATED;
66 } else {
Jamal Hadi Salim1a293212013-12-23 08:02:11 -050067 if (bind)
68 return 0;
Chris Mi65a206c2017-08-30 02:31:59 -040069 tcf_idr_release(*a, bind);
Jamal Hadi Salim1a293212013-12-23 08:02:11 -050070 if (!ovr)
Herbert Xub4219952007-09-27 12:48:05 -070071 return -EEXIST;
Herbert Xub4219952007-09-27 12:48:05 -070072 }
WANG Conga85a9702016-07-25 16:09:41 -070073 p = to_tcf_nat(*a);
Herbert Xub4219952007-09-27 12:48:05 -070074
75 spin_lock_bh(&p->tcf_lock);
76 p->old_addr = parm->old_addr;
77 p->new_addr = parm->new_addr;
78 p->mask = parm->mask;
79 p->flags = parm->flags;
80
81 p->tcf_action = parm->action;
82 spin_unlock_bh(&p->tcf_lock);
83
84 if (ret == ACT_P_CREATED)
Chris Mi65a206c2017-08-30 02:31:59 -040085 tcf_idr_insert(tn, *a);
Herbert Xub4219952007-09-27 12:48:05 -070086
87 return ret;
88}
89
Eric Dumazetdc7f9f62011-07-05 23:25:42 +000090static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
Herbert Xub4219952007-09-27 12:48:05 -070091 struct tcf_result *res)
92{
WANG Conga85a9702016-07-25 16:09:41 -070093 struct tcf_nat *p = to_tcf_nat(a);
Herbert Xub4219952007-09-27 12:48:05 -070094 struct iphdr *iph;
95 __be32 old_addr;
96 __be32 new_addr;
97 __be32 mask;
98 __be32 addr;
99 int egress;
100 int action;
101 int ihl;
Changli Gao36d12692010-08-03 17:39:18 +0000102 int noff;
Herbert Xub4219952007-09-27 12:48:05 -0700103
104 spin_lock(&p->tcf_lock);
105
Jamal Hadi Salim9c4a4e42016-06-06 06:32:53 -0400106 tcf_lastuse_update(&p->tcf_tm);
Herbert Xub4219952007-09-27 12:48:05 -0700107 old_addr = p->old_addr;
108 new_addr = p->new_addr;
109 mask = p->mask;
110 egress = p->flags & TCA_NAT_FLAG_EGRESS;
111 action = p->tcf_action;
112
Eric Dumazetbfe0d022011-01-09 08:30:54 +0000113 bstats_update(&p->tcf_bstats, skb);
Herbert Xub4219952007-09-27 12:48:05 -0700114
115 spin_unlock(&p->tcf_lock);
116
117 if (unlikely(action == TC_ACT_SHOT))
118 goto drop;
119
Changli Gao36d12692010-08-03 17:39:18 +0000120 noff = skb_network_offset(skb);
121 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700122 goto drop;
123
124 iph = ip_hdr(skb);
125
126 if (egress)
127 addr = iph->saddr;
128 else
129 addr = iph->daddr;
130
131 if (!((old_addr ^ addr) & mask)) {
Daniel Borkmann36976492016-02-19 23:05:25 +0100132 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700133 goto drop;
134
135 new_addr &= mask;
136 new_addr |= addr & ~mask;
137
138 /* Rewrite IP header */
139 iph = ip_hdr(skb);
140 if (egress)
141 iph->saddr = new_addr;
142 else
143 iph->daddr = new_addr;
144
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100145 csum_replace4(&iph->check, addr, new_addr);
Changli Gao33c29dd2010-05-29 14:26:59 +0000146 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
147 iph->protocol != IPPROTO_ICMP) {
148 goto out;
Herbert Xub4219952007-09-27 12:48:05 -0700149 }
150
151 ihl = iph->ihl * 4;
152
153 /* It would be nice to share code with stateful NAT. */
154 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
155 case IPPROTO_TCP:
156 {
157 struct tcphdr *tcph;
158
Changli Gao36d12692010-08-03 17:39:18 +0000159 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
Daniel Borkmann36976492016-02-19 23:05:25 +0100160 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700161 goto drop;
162
163 tcph = (void *)(skb_network_header(skb) + ihl);
Tom Herbert4b048d62015-08-17 13:42:25 -0700164 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
165 true);
Herbert Xub4219952007-09-27 12:48:05 -0700166 break;
167 }
168 case IPPROTO_UDP:
169 {
170 struct udphdr *udph;
171
Changli Gao36d12692010-08-03 17:39:18 +0000172 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
Daniel Borkmann36976492016-02-19 23:05:25 +0100173 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700174 goto drop;
175
176 udph = (void *)(skb_network_header(skb) + ihl);
177 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100178 inet_proto_csum_replace4(&udph->check, skb, addr,
Tom Herbert4b048d62015-08-17 13:42:25 -0700179 new_addr, true);
Herbert Xub4219952007-09-27 12:48:05 -0700180 if (!udph->check)
181 udph->check = CSUM_MANGLED_0;
182 }
183 break;
184 }
185 case IPPROTO_ICMP:
186 {
187 struct icmphdr *icmph;
188
Changli Gao36d12692010-08-03 17:39:18 +0000189 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700190 goto drop;
191
192 icmph = (void *)(skb_network_header(skb) + ihl);
193
194 if ((icmph->type != ICMP_DEST_UNREACH) &&
195 (icmph->type != ICMP_TIME_EXCEEDED) &&
196 (icmph->type != ICMP_PARAMETERPROB))
197 break;
198
Changli Gao36d12692010-08-03 17:39:18 +0000199 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
200 noff))
Changli Gao70c2efa2010-07-09 15:33:25 +0000201 goto drop;
202
Changli Gao072d79a2010-07-29 13:41:46 +0000203 icmph = (void *)(skb_network_header(skb) + ihl);
Herbert Xub4219952007-09-27 12:48:05 -0700204 iph = (void *)(icmph + 1);
205 if (egress)
206 addr = iph->daddr;
207 else
208 addr = iph->saddr;
209
210 if ((old_addr ^ addr) & mask)
211 break;
212
Daniel Borkmann36976492016-02-19 23:05:25 +0100213 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
214 sizeof(*iph) + noff))
Herbert Xub4219952007-09-27 12:48:05 -0700215 goto drop;
216
217 icmph = (void *)(skb_network_header(skb) + ihl);
218 iph = (void *)(icmph + 1);
219
220 new_addr &= mask;
221 new_addr |= addr & ~mask;
222
223 /* XXX Fix up the inner checksums. */
224 if (egress)
225 iph->daddr = new_addr;
226 else
227 iph->saddr = new_addr;
228
Patrick McHardybe0ea7d2007-11-30 01:17:11 +1100229 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
Tom Herbert4b048d62015-08-17 13:42:25 -0700230 false);
Herbert Xub4219952007-09-27 12:48:05 -0700231 break;
232 }
233 default:
234 break;
235 }
236
Changli Gao33c29dd2010-05-29 14:26:59 +0000237out:
Herbert Xub4219952007-09-27 12:48:05 -0700238 return action;
239
240drop:
241 spin_lock(&p->tcf_lock);
242 p->tcf_qstats.drops++;
243 spin_unlock(&p->tcf_lock);
244 return TC_ACT_SHOT;
245}
246
247static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
248 int bind, int ref)
249{
250 unsigned char *b = skb_tail_pointer(skb);
WANG Conga85a9702016-07-25 16:09:41 -0700251 struct tcf_nat *p = to_tcf_nat(a);
Eric Dumazet1c40be12010-08-16 20:04:22 +0000252 struct tc_nat opt = {
253 .old_addr = p->old_addr,
254 .new_addr = p->new_addr,
255 .mask = p->mask,
256 .flags = p->flags,
257
258 .index = p->tcf_index,
259 .action = p->tcf_action,
260 .refcnt = p->tcf_refcnt - ref,
261 .bindcnt = p->tcf_bindcnt - bind,
262 };
Herbert Xub4219952007-09-27 12:48:05 -0700263 struct tcf_t t;
Herbert Xub4219952007-09-27 12:48:05 -0700264
David S. Miller1b34ec42012-03-29 05:11:39 -0400265 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
266 goto nla_put_failure;
Jamal Hadi Salim48d8ee12016-06-06 06:32:55 -0400267
268 tcf_tm_dump(&t, &p->tcf_tm);
Nicolas Dichtel9854518e2016-04-26 10:06:18 +0200269 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
David S. Miller1b34ec42012-03-29 05:11:39 -0400270 goto nla_put_failure;
Herbert Xub4219952007-09-27 12:48:05 -0700271
Herbert Xub4219952007-09-27 12:48:05 -0700272 return skb->len;
273
Patrick McHardy7ba699c2008-01-22 22:11:50 -0800274nla_put_failure:
Herbert Xub4219952007-09-27 12:48:05 -0700275 nlmsg_trim(skb, b);
Herbert Xub4219952007-09-27 12:48:05 -0700276 return -1;
277}
278
WANG Congddf97cc2016-02-22 15:57:53 -0800279static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
280 struct netlink_callback *cb, int type,
Alexander Aring41780102018-02-15 10:54:58 -0500281 const struct tc_action_ops *ops,
282 struct netlink_ext_ack *extack)
WANG Congddf97cc2016-02-22 15:57:53 -0800283{
284 struct tc_action_net *tn = net_generic(net, nat_net_id);
285
Alexander Aringb3620142018-02-15 10:54:59 -0500286 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
WANG Congddf97cc2016-02-22 15:57:53 -0800287}
288
Alexander Aring331a9292018-02-15 10:54:57 -0500289static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index,
290 struct netlink_ext_ack *extack)
WANG Congddf97cc2016-02-22 15:57:53 -0800291{
292 struct tc_action_net *tn = net_generic(net, nat_net_id);
293
Chris Mi65a206c2017-08-30 02:31:59 -0400294 return tcf_idr_search(tn, a, index);
WANG Congddf97cc2016-02-22 15:57:53 -0800295}
296
Herbert Xub4219952007-09-27 12:48:05 -0700297static struct tc_action_ops act_nat_ops = {
298 .kind = "nat",
Herbert Xub4219952007-09-27 12:48:05 -0700299 .type = TCA_ACT_NAT,
Herbert Xub4219952007-09-27 12:48:05 -0700300 .owner = THIS_MODULE,
301 .act = tcf_nat,
302 .dump = tcf_nat_dump,
Herbert Xub4219952007-09-27 12:48:05 -0700303 .init = tcf_nat_init,
WANG Congddf97cc2016-02-22 15:57:53 -0800304 .walk = tcf_nat_walker,
305 .lookup = tcf_nat_search,
WANG Conga85a9702016-07-25 16:09:41 -0700306 .size = sizeof(struct tcf_nat),
WANG Congddf97cc2016-02-22 15:57:53 -0800307};
308
309static __net_init int nat_init_net(struct net *net)
310{
311 struct tc_action_net *tn = net_generic(net, nat_net_id);
312
Cong Wangc7e460c2017-11-06 13:47:18 -0800313 return tc_action_net_init(tn, &act_nat_ops);
WANG Congddf97cc2016-02-22 15:57:53 -0800314}
315
Cong Wang039af9c2017-12-11 15:35:03 -0800316static void __net_exit nat_exit_net(struct list_head *net_list)
WANG Congddf97cc2016-02-22 15:57:53 -0800317{
Cong Wang039af9c2017-12-11 15:35:03 -0800318 tc_action_net_exit(net_list, nat_net_id);
WANG Congddf97cc2016-02-22 15:57:53 -0800319}
320
321static struct pernet_operations nat_net_ops = {
322 .init = nat_init_net,
Cong Wang039af9c2017-12-11 15:35:03 -0800323 .exit_batch = nat_exit_net,
WANG Congddf97cc2016-02-22 15:57:53 -0800324 .id = &nat_net_id,
325 .size = sizeof(struct tc_action_net),
Herbert Xub4219952007-09-27 12:48:05 -0700326};
327
328MODULE_DESCRIPTION("Stateless NAT actions");
329MODULE_LICENSE("GPL");
330
331static int __init nat_init_module(void)
332{
WANG Congddf97cc2016-02-22 15:57:53 -0800333 return tcf_register_action(&act_nat_ops, &nat_net_ops);
Herbert Xub4219952007-09-27 12:48:05 -0700334}
335
336static void __exit nat_cleanup_module(void)
337{
WANG Congddf97cc2016-02-22 15:57:53 -0800338 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
Herbert Xub4219952007-09-27 12:48:05 -0700339}
340
341module_init(nat_init_module);
342module_exit(nat_cleanup_module);