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2874c5fd 1// SPDX-License-Identifier: GPL-2.0-or-later
b4219952
HX
2/*
3 * Stateless NAT actions
4 *
5 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
b4219952
HX
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>
1e45d043 20#include <net/pkt_cls.h>
b4219952
HX
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
28
c7d03a00 29static unsigned int nat_net_id;
a85a970a 30static struct tc_action_ops act_nat_ops;
ddf97ccd 31
53b2bf3f
PM
32static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
33 [TCA_NAT_PARMS] = { .len = sizeof(struct tc_nat) },
34};
35
c1b52739 36static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
589dad6d 37 struct tc_action **a, int ovr, int bind,
85d0966f
DC
38 bool rtnl_held, struct tcf_proto *tp,
39 struct netlink_ext_ack *extack)
b4219952 40{
ddf97ccd 41 struct tc_action_net *tn = net_generic(net, nat_net_id);
7ba699c6 42 struct nlattr *tb[TCA_NAT_MAX + 1];
1e45d043 43 struct tcf_chain *goto_ch = NULL;
b4219952 44 struct tc_nat *parm;
cee63723 45 int ret = 0, err;
b4219952 46 struct tcf_nat *p;
7be8ef2c 47 u32 index;
b4219952 48
cee63723 49 if (nla == NULL)
b4219952
HX
50 return -EINVAL;
51
8cb08174
JB
52 err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
53 NULL);
cee63723
PM
54 if (err < 0)
55 return err;
56
53b2bf3f 57 if (tb[TCA_NAT_PARMS] == NULL)
b4219952 58 return -EINVAL;
7ba699c6 59 parm = nla_data(tb[TCA_NAT_PARMS]);
7be8ef2c
DL
60 index = parm->index;
61 err = tcf_idr_check_alloc(tn, &index, a, bind);
0190c1d4 62 if (!err) {
7be8ef2c 63 ret = tcf_idr_create(tn, index, est, a,
65a206c0 64 &act_nat_ops, bind, false);
0190c1d4 65 if (ret) {
7be8ef2c 66 tcf_idr_cleanup(tn, index);
86062033 67 return ret;
0190c1d4 68 }
b4219952 69 ret = ACT_P_CREATED;
0190c1d4 70 } else if (err > 0) {
1a29321e
JHS
71 if (bind)
72 return 0;
4e8ddd7f
VB
73 if (!ovr) {
74 tcf_idr_release(*a, bind);
b4219952 75 return -EEXIST;
4e8ddd7f 76 }
0190c1d4
VB
77 } else {
78 return err;
b4219952 79 }
1e45d043
DC
80 err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
81 if (err < 0)
82 goto release_idr;
a85a970a 83 p = to_tcf_nat(*a);
b4219952
HX
84
85 spin_lock_bh(&p->tcf_lock);
86 p->old_addr = parm->old_addr;
87 p->new_addr = parm->new_addr;
88 p->mask = parm->mask;
89 p->flags = parm->flags;
90
1e45d043 91 goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
b4219952 92 spin_unlock_bh(&p->tcf_lock);
1e45d043
DC
93 if (goto_ch)
94 tcf_chain_put_by_act(goto_ch);
b4219952
HX
95
96 if (ret == ACT_P_CREATED)
65a206c0 97 tcf_idr_insert(tn, *a);
b4219952
HX
98
99 return ret;
1e45d043
DC
100release_idr:
101 tcf_idr_release(*a, bind);
102 return err;
b4219952
HX
103}
104
0390514f
JHS
105static int tcf_nat_act(struct sk_buff *skb, const struct tc_action *a,
106 struct tcf_result *res)
b4219952 107{
a85a970a 108 struct tcf_nat *p = to_tcf_nat(a);
b4219952
HX
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;
36d12690 117 int noff;
b4219952
HX
118
119 spin_lock(&p->tcf_lock);
120
9c4a4e48 121 tcf_lastuse_update(&p->tcf_tm);
b4219952
HX
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
bfe0d029 128 bstats_update(&p->tcf_bstats, skb);
b4219952
HX
129
130 spin_unlock(&p->tcf_lock);
131
132 if (unlikely(action == TC_ACT_SHOT))
133 goto drop;
134
36d12690
CG
135 noff = skb_network_offset(skb);
136 if (!pskb_may_pull(skb, sizeof(*iph) + noff))
b4219952
HX
137 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)) {
3697649f 147 if (skb_try_make_writable(skb, sizeof(*iph) + noff))
b4219952
HX
148 goto drop;
149
150 new_addr &= mask;
151 new_addr |= addr & ~mask;
152
153 /* Rewrite IP header */
154 iph = ip_hdr(skb);
155 if (egress)
156 iph->saddr = new_addr;
157 else
158 iph->daddr = new_addr;
159
be0ea7d5 160 csum_replace4(&iph->check, addr, new_addr);
33c29dde
CG
161 } else if ((iph->frag_off & htons(IP_OFFSET)) ||
162 iph->protocol != IPPROTO_ICMP) {
163 goto out;
b4219952
HX
164 }
165
166 ihl = iph->ihl * 4;
167
168 /* It would be nice to share code with stateful NAT. */
169 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
170 case IPPROTO_TCP:
171 {
172 struct tcphdr *tcph;
173
36d12690 174 if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
3697649f 175 skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
b4219952
HX
176 goto drop;
177
178 tcph = (void *)(skb_network_header(skb) + ihl);
4b048d6d
TH
179 inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
180 true);
b4219952
HX
181 break;
182 }
183 case IPPROTO_UDP:
184 {
185 struct udphdr *udph;
186
36d12690 187 if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
3697649f 188 skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
b4219952
HX
189 goto drop;
190
191 udph = (void *)(skb_network_header(skb) + ihl);
192 if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
be0ea7d5 193 inet_proto_csum_replace4(&udph->check, skb, addr,
4b048d6d 194 new_addr, true);
b4219952
HX
195 if (!udph->check)
196 udph->check = CSUM_MANGLED_0;
197 }
198 break;
199 }
200 case IPPROTO_ICMP:
201 {
202 struct icmphdr *icmph;
203
36d12690 204 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
b4219952
HX
205 goto drop;
206
207 icmph = (void *)(skb_network_header(skb) + ihl);
208
209 if ((icmph->type != ICMP_DEST_UNREACH) &&
210 (icmph->type != ICMP_TIME_EXCEEDED) &&
211 (icmph->type != ICMP_PARAMETERPROB))
212 break;
213
36d12690
CG
214 if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
215 noff))
70c2efa5
CG
216 goto drop;
217
072d79a3 218 icmph = (void *)(skb_network_header(skb) + ihl);
b4219952
HX
219 iph = (void *)(icmph + 1);
220 if (egress)
221 addr = iph->daddr;
222 else
223 addr = iph->saddr;
224
225 if ((old_addr ^ addr) & mask)
226 break;
227
3697649f
DB
228 if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
229 sizeof(*iph) + noff))
b4219952
HX
230 goto drop;
231
232 icmph = (void *)(skb_network_header(skb) + ihl);
233 iph = (void *)(icmph + 1);
234
235 new_addr &= mask;
236 new_addr |= addr & ~mask;
237
238 /* XXX Fix up the inner checksums. */
239 if (egress)
240 iph->daddr = new_addr;
241 else
242 iph->saddr = new_addr;
243
be0ea7d5 244 inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
4b048d6d 245 false);
b4219952
HX
246 break;
247 }
248 default:
249 break;
250 }
251
33c29dde 252out:
b4219952
HX
253 return action;
254
255drop:
256 spin_lock(&p->tcf_lock);
257 p->tcf_qstats.drops++;
258 spin_unlock(&p->tcf_lock);
259 return TC_ACT_SHOT;
260}
261
262static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
263 int bind, int ref)
264{
265 unsigned char *b = skb_tail_pointer(skb);
a85a970a 266 struct tcf_nat *p = to_tcf_nat(a);
1c40be12 267 struct tc_nat opt = {
1c40be12 268 .index = p->tcf_index,
036bb443
VB
269 .refcnt = refcount_read(&p->tcf_refcnt) - ref,
270 .bindcnt = atomic_read(&p->tcf_bindcnt) - bind,
1c40be12 271 };
b4219952 272 struct tcf_t t;
b4219952 273
f20a4d01
VB
274 spin_lock_bh(&p->tcf_lock);
275 opt.old_addr = p->old_addr;
276 opt.new_addr = p->new_addr;
277 opt.mask = p->mask;
278 opt.flags = p->flags;
279 opt.action = p->tcf_action;
280
1b34ec43
DM
281 if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
282 goto nla_put_failure;
48d8ee16
JHS
283
284 tcf_tm_dump(&t, &p->tcf_tm);
9854518e 285 if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
1b34ec43 286 goto nla_put_failure;
f20a4d01 287 spin_unlock_bh(&p->tcf_lock);
b4219952 288
b4219952
HX
289 return skb->len;
290
7ba699c6 291nla_put_failure:
f20a4d01 292 spin_unlock_bh(&p->tcf_lock);
b4219952 293 nlmsg_trim(skb, b);
b4219952
HX
294 return -1;
295}
296
ddf97ccd
WC
297static int tcf_nat_walker(struct net *net, struct sk_buff *skb,
298 struct netlink_callback *cb, int type,
41780105
AA
299 const struct tc_action_ops *ops,
300 struct netlink_ext_ack *extack)
ddf97ccd
WC
301{
302 struct tc_action_net *tn = net_generic(net, nat_net_id);
303
b3620145 304 return tcf_generic_walker(tn, skb, cb, type, ops, extack);
ddf97ccd
WC
305}
306
f061b48c 307static int tcf_nat_search(struct net *net, struct tc_action **a, u32 index)
ddf97ccd
WC
308{
309 struct tc_action_net *tn = net_generic(net, nat_net_id);
310
65a206c0 311 return tcf_idr_search(tn, a, index);
ddf97ccd
WC
312}
313
b4219952
HX
314static struct tc_action_ops act_nat_ops = {
315 .kind = "nat",
eddd2cf1 316 .id = TCA_ID_NAT,
b4219952 317 .owner = THIS_MODULE,
0390514f 318 .act = tcf_nat_act,
b4219952 319 .dump = tcf_nat_dump,
b4219952 320 .init = tcf_nat_init,
ddf97ccd
WC
321 .walk = tcf_nat_walker,
322 .lookup = tcf_nat_search,
a85a970a 323 .size = sizeof(struct tcf_nat),
ddf97ccd
WC
324};
325
326static __net_init int nat_init_net(struct net *net)
327{
328 struct tc_action_net *tn = net_generic(net, nat_net_id);
329
981471bd 330 return tc_action_net_init(net, tn, &act_nat_ops);
ddf97ccd
WC
331}
332
039af9c6 333static void __net_exit nat_exit_net(struct list_head *net_list)
ddf97ccd 334{
039af9c6 335 tc_action_net_exit(net_list, nat_net_id);
ddf97ccd
WC
336}
337
338static struct pernet_operations nat_net_ops = {
339 .init = nat_init_net,
039af9c6 340 .exit_batch = nat_exit_net,
ddf97ccd
WC
341 .id = &nat_net_id,
342 .size = sizeof(struct tc_action_net),
b4219952
HX
343};
344
345MODULE_DESCRIPTION("Stateless NAT actions");
346MODULE_LICENSE("GPL");
347
348static int __init nat_init_module(void)
349{
ddf97ccd 350 return tcf_register_action(&act_nat_ops, &nat_net_ops);
b4219952
HX
351}
352
353static void __exit nat_cleanup_module(void)
354{
ddf97ccd 355 tcf_unregister_action(&act_nat_ops, &nat_net_ops);
b4219952
HX
356}
357
358module_init(nat_init_module);
359module_exit(nat_cleanup_module);