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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Stateless NAT actions
4 *
5 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
6 */
7
8#include <linux/errno.h>
9#include <linux/init.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/netfilter.h>
13#include <linux/rtnetlink.h>
14#include <linux/skbuff.h>
15#include <linux/slab.h>
16#include <linux/spinlock.h>
17#include <linux/string.h>
18#include <linux/tc_act/tc_nat.h>
19#include <net/act_api.h>
20#include <net/pkt_cls.h>
21#include <net/icmp.h>
22#include <net/ip.h>
23#include <net/netlink.h>
24#include <net/tc_act/tc_nat.h>
25#include <net/tcp.h>
26#include <net/udp.h>
27#include <net/tc_wrapper.h>
28
29static struct tc_action_ops act_nat_ops;
30
31static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
32 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
33};
34
35static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
36 struct tc_action **a, struct tcf_proto *tp,
37 u32 flags, struct netlink_ext_ack *extack)
38{
39 struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
40 bool bind = flags & TCA_ACT_FLAGS_BIND;
41 struct tcf_nat_parms *nparm, *oparm;
42 struct nlattr *tb[TCA_NAT_MAX + 1];
43 struct tcf_chain *goto_ch = NULL;
44 struct tc_nat *parm;
45 int ret = 0, err;
46 struct tcf_nat *p;
47 u32 index;
48
49 if (nla == NULL)
50 return -EINVAL;
51
52 err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
53 NULL);
54 if (err < 0)
55 return err;
56
57 if (tb[TCA_NAT_PARMS] == NULL)
58 return -EINVAL;
59 parm = nla_data(tb[TCA_NAT_PARMS]);
60 index = parm->index;
61 err = tcf_idr_check_alloc(tn, &index, a, bind);
62 if (!err) {
63 ret = tcf_idr_create_from_flags(tn, index, est, a, &act_nat_ops,
64 bind, flags);
65 if (ret) {
66 tcf_idr_cleanup(tn, index);
67 return ret;
68 }
69 ret = ACT_P_CREATED;
70 } else if (err > 0) {
71 if (bind)
72 return ACT_P_BOUND;
73 if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
74 tcf_idr_release(*a, bind);
75 return -EEXIST;
76 }
77 } else {
78 return err;
79 }
80 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
81 if (err < 0)
82 goto release_idr;
83
84 nparm = kzalloc(sizeof(*nparm), GFP_KERNEL);
85 if (!nparm) {
86 err = -ENOMEM;
87 goto release_idr;
88 }
89
90 nparm->old_addr = parm->old_addr;
91 nparm->new_addr = parm->new_addr;
92 nparm->mask = parm->mask;
93 nparm->flags = parm->flags;
94
95 p = to_tcf_nat(*a);
96
97 spin_lock_bh(&p->tcf_lock);
98 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
99 oparm = rcu_replace_pointer(p->parms, nparm, lockdep_is_held(&p->tcf_lock));
100 spin_unlock_bh(&p->tcf_lock);
101
102 if (goto_ch)
103 tcf_chain_put_by_act(goto_ch);
104
105 if (oparm)
106 kfree_rcu(oparm, rcu);
107
108 return ret;
109release_idr:
110 tcf_idr_release(*a, bind);
111 return err;
112}
113
114TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb,
115 const struct tc_action *a,
116 struct tcf_result *res)
117{
118 struct tcf_nat *p = to_tcf_nat(a);
119 struct tcf_nat_parms *parms;
120 struct iphdr *iph;
121 __be32 old_addr;
122 __be32 new_addr;
123 __be32 mask;
124 __be32 addr;
125 int egress;
126 int action;
127 int ihl;
128 int noff;
129
130 tcf_lastuse_update(&p->tcf_tm);
131 tcf_action_update_bstats(&p->common, skb);
132
133 action = READ_ONCE(p->tcf_action);
134
135 parms = rcu_dereference_bh(p->parms);
136 old_addr = parms->old_addr;
137 new_addr = parms->new_addr;
138 mask = parms->mask;
139 egress = parms->flags & TCA_NAT_FLAG_EGRESS;
140
141 if (unlikely(action == TC_ACT_SHOT))
142 goto drop;
143
144 noff = skb_network_offset(skb);
145 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
146 goto drop;
147
148 iph = ip_hdr(skb);
149
150 if (egress)
151 addr = iph->saddr;
152 else
153 addr = iph->daddr;
154
155 if (!((old_addr ^ addr) & mask)) {
156 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
157 goto drop;
158
159 new_addr &= mask;
160 new_addr |= addr & ~mask;
161
162 /* Rewrite IP header */
163 iph = ip_hdr(skb);
164 if (egress)
165 iph->saddr = new_addr;
166 else
167 iph->daddr = new_addr;
168
169 csum_replace4(&iph->check, addr, new_addr);
170 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
171 iph->protocol != IPPROTO_ICMP) {
172 goto out;
173 }
174
175 ihl = iph->ihl * 4;
176
177 /* It would be nice to share code with stateful NAT. */
178 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
179 case IPPROTO_TCP:
180 {
181 struct tcphdr *tcph;
182
183 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
184 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
185 goto drop;
186
187 tcph = (void *)(skb_network_header(skb) + ihl);
188 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
189 true);
190 break;
191 }
192 case IPPROTO_UDP:
193 {
194 struct udphdr *udph;
195
196 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
197 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
198 goto drop;
199
200 udph = (void *)(skb_network_header(skb) + ihl);
201 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
202 inet_proto_csum_replace4(&udph->check, skb, addr,
203 new_addr, true);
204 if (!udph->check)
205 udph->check = CSUM_MANGLED_0;
206 }
207 break;
208 }
209 case IPPROTO_ICMP:
210 {
211 struct icmphdr *icmph;
212
213 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
214 goto drop;
215
216 icmph = (void *)(skb_network_header(skb) + ihl);
217
218 if (!icmp_is_err(icmph->type))
219 break;
220
221 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
222 noff))
223 goto drop;
224
225 icmph = (void *)(skb_network_header(skb) + ihl);
226 iph = (void *)(icmph + 1);
227 if (egress)
228 addr = iph->daddr;
229 else
230 addr = iph->saddr;
231
232 if ((old_addr ^ addr) & mask)
233 break;
234
235 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
236 sizeof(*iph) + noff))
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
251 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
252 false);
253 break;
254 }
255 default:
256 break;
257 }
258
259out:
260 return action;
261
262drop:
263 tcf_action_inc_drop_qstats(&p->common);
264 return TC_ACT_SHOT;
265}
266
267static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
268 int bind, int ref)
269{
270 unsigned char *b = skb_tail_pointer(skb);
271 struct tcf_nat *p = to_tcf_nat(a);
272 struct tc_nat opt = {
273 .index = p->tcf_index,
274 .refcnt = refcount_read(&p->tcf_refcnt) - ref,
275 .bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
276 };
277 struct tcf_nat_parms *parms;
278 struct tcf_t t;
279
280 spin_lock_bh(&p->tcf_lock);
281
282 opt.action = p->tcf_action;
283
284 parms = rcu_dereference_protected(p->parms, lockdep_is_held(&p->tcf_lock));
285
286 opt.old_addr = parms->old_addr;
287 opt.new_addr = parms->new_addr;
288 opt.mask = parms->mask;
289 opt.flags = parms->flags;
290
291 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
292 goto nla_put_failure;
293
294 tcf_tm_dump(&t, &p->tcf_tm);
295 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
296 goto nla_put_failure;
297 spin_unlock_bh(&p->tcf_lock);
298
299 return skb->len;
300
301nla_put_failure:
302 spin_unlock_bh(&p->tcf_lock);
303 nlmsg_trim(skb, b);
304 return -1;
305}
306
307static void tcf_nat_cleanup(struct tc_action *a)
308{
309 struct tcf_nat *p = to_tcf_nat(a);
310 struct tcf_nat_parms *parms;
311
312 parms = rcu_dereference_protected(p->parms, 1);
313 if (parms)
314 kfree_rcu(parms, rcu);
315}
316
317static struct tc_action_ops act_nat_ops = {
318 .kind = "nat",
319 .id = TCA_ID_NAT,
320 .owner = THIS_MODULE,
321 .act = tcf_nat_act,
322 .dump = tcf_nat_dump,
323 .init = tcf_nat_init,
324 .cleanup = tcf_nat_cleanup,
325 .size = sizeof(struct tcf_nat),
326};
327MODULE_ALIAS_NET_ACT("nat");
328
329static __net_init int nat_init_net(struct net *net)
330{
331 struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
332
333 return tc_action_net_init(net, tn, &act_nat_ops);
334}
335
336static void __net_exit nat_exit_net(struct list_head *net_list)
337{
338 tc_action_net_exit(net_list, act_nat_ops.net_id);
339}
340
341static struct pernet_operations nat_net_ops = {
342 .init = nat_init_net,
343 .exit_batch = nat_exit_net,
344 .id = &act_nat_ops.net_id,
345 .size = sizeof(struct tc_action_net),
346};
347
348MODULE_DESCRIPTION("Stateless NAT actions");
349MODULE_LICENSE("GPL");
350
351static int __init nat_init_module(void)
352{
353 return tcf_register_action(&act_nat_ops, &nat_net_ops);
354}
355
356static void __exit nat_cleanup_module(void)
357{
358 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
359}
360
361module_init(nat_init_module);
362module_exit(nat_cleanup_module);
1/*
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
32static unsigned int nat_net_id;
33static struct tc_action_ops act_nat_ops;
34
35static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
36 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
37};
38
39static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
40 struct tc_action **a, int ovr, int bind,
41 struct netlink_ext_ack *extack)
42{
43 struct tc_action_net *tn = net_generic(net, nat_net_id);
44 struct nlattr *tb[TCA_NAT_MAX + 1];
45 struct tc_nat *parm;
46 int ret = 0, err;
47 struct tcf_nat *p;
48
49 if (nla == NULL)
50 return -EINVAL;
51
52 err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy, NULL);
53 if (err < 0)
54 return err;
55
56 if (tb[TCA_NAT_PARMS] == NULL)
57 return -EINVAL;
58 parm = nla_data(tb[TCA_NAT_PARMS]);
59
60 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);
63 if (ret)
64 return ret;
65 ret = ACT_P_CREATED;
66 } else {
67 if (bind)
68 return 0;
69 tcf_idr_release(*a, bind);
70 if (!ovr)
71 return -EEXIST;
72 }
73 p = to_tcf_nat(*a);
74
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)
85 tcf_idr_insert(tn, *a);
86
87 return ret;
88}
89
90static int tcf_nat(struct sk_buff *skb, const struct tc_action *a,
91 struct tcf_result *res)
92{
93 struct tcf_nat *p = to_tcf_nat(a);
94 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;
102 int noff;
103
104 spin_lock(&p->tcf_lock);
105
106 tcf_lastuse_update(&p->tcf_tm);
107 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
113 bstats_update(&p->tcf_bstats, skb);
114
115 spin_unlock(&p->tcf_lock);
116
117 if (unlikely(action == TC_ACT_SHOT))
118 goto drop;
119
120 noff = skb_network_offset(skb);
121 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
122 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)) {
132 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
133 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
145 csum_replace4(&iph->check, addr, new_addr);
146 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
147 iph->protocol != IPPROTO_ICMP) {
148 goto out;
149 }
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
159 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
160 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
161 goto drop;
162
163 tcph = (void *)(skb_network_header(skb) + ihl);
164 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
165 true);
166 break;
167 }
168 case IPPROTO_UDP:
169 {
170 struct udphdr *udph;
171
172 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
173 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
174 goto drop;
175
176 udph = (void *)(skb_network_header(skb) + ihl);
177 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
178 inet_proto_csum_replace4(&udph->check, skb, addr,
179 new_addr, true);
180 if (!udph->check)
181 udph->check = CSUM_MANGLED_0;
182 }
183 break;
184 }
185 case IPPROTO_ICMP:
186 {
187 struct icmphdr *icmph;
188
189 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
190 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
199 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
200 noff))
201 goto drop;
202
203 icmph = (void *)(skb_network_header(skb) + ihl);
204 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
213 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
214 sizeof(*iph) + noff))
215 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
229 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
230 false);
231 break;
232 }
233 default:
234 break;
235 }
236
237out:
238 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);
251 struct tcf_nat *p = to_tcf_nat(a);
252 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 };
263 struct tcf_t t;
264
265 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
266 goto nla_put_failure;
267
268 tcf_tm_dump(&t, &p->tcf_tm);
269 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
270 goto nla_put_failure;
271
272 return skb->len;
273
274nla_put_failure:
275 nlmsg_trim(skb, b);
276 return -1;
277}
278
279static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
280 struct netlink_callback *cb, int type,
281 const struct tc_action_ops *ops,
282 struct netlink_ext_ack *extack)
283{
284 struct tc_action_net *tn = net_generic(net, nat_net_id);
285
286 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
287}
288
289static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index,
290 struct netlink_ext_ack *extack)
291{
292 struct tc_action_net *tn = net_generic(net, nat_net_id);
293
294 return tcf_idr_search(tn, a, index);
295}
296
297static struct tc_action_ops act_nat_ops = {
298 .kind = "nat",
299 .type = TCA_ACT_NAT,
300 .owner = THIS_MODULE,
301 .act = tcf_nat,
302 .dump = tcf_nat_dump,
303 .init = tcf_nat_init,
304 .walk = tcf_nat_walker,
305 .lookup = tcf_nat_search,
306 .size = sizeof(struct tcf_nat),
307};
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
313 return tc_action_net_init(tn, &act_nat_ops);
314}
315
316static void __net_exit nat_exit_net(struct list_head *net_list)
317{
318 tc_action_net_exit(net_list, nat_net_id);
319}
320
321static struct pernet_operations nat_net_ops = {
322 .init = nat_init_net,
323 .exit_batch = nat_exit_net,
324 .id = &nat_net_id,
325 .size = sizeof(struct tc_action_net),
326};
327
328MODULE_DESCRIPTION("Stateless NAT actions");
329MODULE_LICENSE("GPL");
330
331static int __init nat_init_module(void)
332{
333 return tcf_register_action(&act_nat_ops, &nat_net_ops);
334}
335
336static void __exit nat_cleanup_module(void)
337{
338 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
339}
340
341module_init(nat_init_module);
342module_exit(nat_cleanup_module);