1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5 * (C) 2011 Patrick McHardy <kaber@trash.net>
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/module.h>
11 #include <linux/types.h>
12 #include <linux/timer.h>
13 #include <linux/skbuff.h>
14 #include <linux/gfp.h>
15 #include <net/xfrm.h>
16 #include <linux/siphash.h>
17 #include <linux/rtnetlink.h>
18
19 #include <net/netfilter/nf_conntrack_bpf.h>
20 #include <net/netfilter/nf_conntrack_core.h>
21 #include <net/netfilter/nf_conntrack_helper.h>
22 #include <net/netfilter/nf_conntrack_seqadj.h>
23 #include <net/netfilter/nf_conntrack_zones.h>
24 #include <net/netfilter/nf_nat.h>
25 #include <net/netfilter/nf_nat_helper.h>
26 #include <uapi/linux/netfilter/nf_nat.h>
27
28 #include "nf_internals.h"
29
30 static spinlock_t nf_nat_locks[CONNTRACK_LOCKS];
31
32 static DEFINE_MUTEX(nf_nat_proto_mutex);
33 static unsigned int nat_net_id __read_mostly;
34
35 static struct hlist_head *nf_nat_bysource __read_mostly;
36 static unsigned int nf_nat_htable_size __read_mostly;
37 static siphash_aligned_key_t nf_nat_hash_rnd;
38
39 struct nf_nat_lookup_hook_priv {
40 struct nf_hook_entries __rcu *entries;
41
42 struct rcu_head rcu_head;
43 };
44
45 struct nf_nat_hooks_net {
46 struct nf_hook_ops *nat_hook_ops;
47 unsigned int users;
48 };
49
50 struct nat_net {
51 struct nf_nat_hooks_net nat_proto_net[NFPROTO_NUMPROTO];
52 };
53
54 #ifdef CONFIG_XFRM
nf_nat_ipv4_decode_session(struct sk_buff * skb,const struct nf_conn * ct,enum ip_conntrack_dir dir,unsigned long statusbit,struct flowi * fl)55 static void nf_nat_ipv4_decode_session(struct sk_buff *skb,
56 const struct nf_conn *ct,
57 enum ip_conntrack_dir dir,
58 unsigned long statusbit,
59 struct flowi *fl)
60 {
61 const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
62 struct flowi4 *fl4 = &fl->u.ip4;
63
64 if (ct->status & statusbit) {
65 fl4->daddr = t->dst.u3.ip;
66 if (t->dst.protonum == IPPROTO_TCP ||
67 t->dst.protonum == IPPROTO_UDP ||
68 t->dst.protonum == IPPROTO_UDPLITE ||
69 t->dst.protonum == IPPROTO_DCCP ||
70 t->dst.protonum == IPPROTO_SCTP)
71 fl4->fl4_dport = t->dst.u.all;
72 }
73
74 statusbit ^= IPS_NAT_MASK;
75
76 if (ct->status & statusbit) {
77 fl4->saddr = t->src.u3.ip;
78 if (t->dst.protonum == IPPROTO_TCP ||
79 t->dst.protonum == IPPROTO_UDP ||
80 t->dst.protonum == IPPROTO_UDPLITE ||
81 t->dst.protonum == IPPROTO_DCCP ||
82 t->dst.protonum == IPPROTO_SCTP)
83 fl4->fl4_sport = t->src.u.all;
84 }
85 }
86
nf_nat_ipv6_decode_session(struct sk_buff * skb,const struct nf_conn * ct,enum ip_conntrack_dir dir,unsigned long statusbit,struct flowi * fl)87 static void nf_nat_ipv6_decode_session(struct sk_buff *skb,
88 const struct nf_conn *ct,
89 enum ip_conntrack_dir dir,
90 unsigned long statusbit,
91 struct flowi *fl)
92 {
93 #if IS_ENABLED(CONFIG_IPV6)
94 const struct nf_conntrack_tuple *t = &ct->tuplehash[dir].tuple;
95 struct flowi6 *fl6 = &fl->u.ip6;
96
97 if (ct->status & statusbit) {
98 fl6->daddr = t->dst.u3.in6;
99 if (t->dst.protonum == IPPROTO_TCP ||
100 t->dst.protonum == IPPROTO_UDP ||
101 t->dst.protonum == IPPROTO_UDPLITE ||
102 t->dst.protonum == IPPROTO_DCCP ||
103 t->dst.protonum == IPPROTO_SCTP)
104 fl6->fl6_dport = t->dst.u.all;
105 }
106
107 statusbit ^= IPS_NAT_MASK;
108
109 if (ct->status & statusbit) {
110 fl6->saddr = t->src.u3.in6;
111 if (t->dst.protonum == IPPROTO_TCP ||
112 t->dst.protonum == IPPROTO_UDP ||
113 t->dst.protonum == IPPROTO_UDPLITE ||
114 t->dst.protonum == IPPROTO_DCCP ||
115 t->dst.protonum == IPPROTO_SCTP)
116 fl6->fl6_sport = t->src.u.all;
117 }
118 #endif
119 }
120
__nf_nat_decode_session(struct sk_buff * skb,struct flowi * fl)121 static void __nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl)
122 {
123 const struct nf_conn *ct;
124 enum ip_conntrack_info ctinfo;
125 enum ip_conntrack_dir dir;
126 unsigned long statusbit;
127 u8 family;
128
129 ct = nf_ct_get(skb, &ctinfo);
130 if (ct == NULL)
131 return;
132
133 family = nf_ct_l3num(ct);
134 dir = CTINFO2DIR(ctinfo);
135 if (dir == IP_CT_DIR_ORIGINAL)
136 statusbit = IPS_DST_NAT;
137 else
138 statusbit = IPS_SRC_NAT;
139
140 switch (family) {
141 case NFPROTO_IPV4:
142 nf_nat_ipv4_decode_session(skb, ct, dir, statusbit, fl);
143 return;
144 case NFPROTO_IPV6:
145 nf_nat_ipv6_decode_session(skb, ct, dir, statusbit, fl);
146 return;
147 }
148 }
149 #endif /* CONFIG_XFRM */
150
151 /* We keep an extra hash for each conntrack, for fast searching. */
152 static unsigned int
hash_by_src(const struct net * net,const struct nf_conntrack_zone * zone,const struct nf_conntrack_tuple * tuple)153 hash_by_src(const struct net *net,
154 const struct nf_conntrack_zone *zone,
155 const struct nf_conntrack_tuple *tuple)
156 {
157 unsigned int hash;
158 struct {
159 struct nf_conntrack_man src;
160 u32 net_mix;
161 u32 protonum;
162 u32 zone;
163 } __aligned(SIPHASH_ALIGNMENT) combined;
164
165 get_random_once(&nf_nat_hash_rnd, sizeof(nf_nat_hash_rnd));
166
167 memset(&combined, 0, sizeof(combined));
168
169 /* Original src, to ensure we map it consistently if poss. */
170 combined.src = tuple->src;
171 combined.net_mix = net_hash_mix(net);
172 combined.protonum = tuple->dst.protonum;
173
174 /* Zone ID can be used provided its valid for both directions */
175 if (zone->dir == NF_CT_DEFAULT_ZONE_DIR)
176 combined.zone = zone->id;
177
178 hash = siphash(&combined, sizeof(combined), &nf_nat_hash_rnd);
179
180 return reciprocal_scale(hash, nf_nat_htable_size);
181 }
182
183 /* Is this tuple already taken? (not by us) */
184 static int
nf_nat_used_tuple(const struct nf_conntrack_tuple * tuple,const struct nf_conn * ignored_conntrack)185 nf_nat_used_tuple(const struct nf_conntrack_tuple *tuple,
186 const struct nf_conn *ignored_conntrack)
187 {
188 /* Conntrack tracking doesn't keep track of outgoing tuples; only
189 * incoming ones. NAT means they don't have a fixed mapping,
190 * so we invert the tuple and look for the incoming reply.
191 *
192 * We could keep a separate hash if this proves too slow.
193 */
194 struct nf_conntrack_tuple reply;
195
196 nf_ct_invert_tuple(&reply, tuple);
197 return nf_conntrack_tuple_taken(&reply, ignored_conntrack);
198 }
199
nf_nat_inet_in_range(const struct nf_conntrack_tuple * t,const struct nf_nat_range2 * range)200 static bool nf_nat_inet_in_range(const struct nf_conntrack_tuple *t,
201 const struct nf_nat_range2 *range)
202 {
203 if (t->src.l3num == NFPROTO_IPV4)
204 return ntohl(t->src.u3.ip) >= ntohl(range->min_addr.ip) &&
205 ntohl(t->src.u3.ip) <= ntohl(range->max_addr.ip);
206
207 return ipv6_addr_cmp(&t->src.u3.in6, &range->min_addr.in6) >= 0 &&
208 ipv6_addr_cmp(&t->src.u3.in6, &range->max_addr.in6) <= 0;
209 }
210
211 /* Is the manipable part of the tuple between min and max incl? */
l4proto_in_range(const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype,const union nf_conntrack_man_proto * min,const union nf_conntrack_man_proto * max)212 static bool l4proto_in_range(const struct nf_conntrack_tuple *tuple,
213 enum nf_nat_manip_type maniptype,
214 const union nf_conntrack_man_proto *min,
215 const union nf_conntrack_man_proto *max)
216 {
217 __be16 port;
218
219 switch (tuple->dst.protonum) {
220 case IPPROTO_ICMP:
221 case IPPROTO_ICMPV6:
222 return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
223 ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
224 case IPPROTO_GRE: /* all fall though */
225 case IPPROTO_TCP:
226 case IPPROTO_UDP:
227 case IPPROTO_UDPLITE:
228 case IPPROTO_DCCP:
229 case IPPROTO_SCTP:
230 if (maniptype == NF_NAT_MANIP_SRC)
231 port = tuple->src.u.all;
232 else
233 port = tuple->dst.u.all;
234
235 return ntohs(port) >= ntohs(min->all) &&
236 ntohs(port) <= ntohs(max->all);
237 default:
238 return true;
239 }
240 }
241
242 /* If we source map this tuple so reply looks like reply_tuple, will
243 * that meet the constraints of range.
244 */
in_range(const struct nf_conntrack_tuple * tuple,const struct nf_nat_range2 * range)245 static int in_range(const struct nf_conntrack_tuple *tuple,
246 const struct nf_nat_range2 *range)
247 {
248 /* If we are supposed to map IPs, then we must be in the
249 * range specified, otherwise let this drag us onto a new src IP.
250 */
251 if (range->flags & NF_NAT_RANGE_MAP_IPS &&
252 !nf_nat_inet_in_range(tuple, range))
253 return 0;
254
255 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
256 return 1;
257
258 return l4proto_in_range(tuple, NF_NAT_MANIP_SRC,
259 &range->min_proto, &range->max_proto);
260 }
261
262 static inline int
same_src(const struct nf_conn * ct,const struct nf_conntrack_tuple * tuple)263 same_src(const struct nf_conn *ct,
264 const struct nf_conntrack_tuple *tuple)
265 {
266 const struct nf_conntrack_tuple *t;
267
268 t = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
269 return (t->dst.protonum == tuple->dst.protonum &&
270 nf_inet_addr_cmp(&t->src.u3, &tuple->src.u3) &&
271 t->src.u.all == tuple->src.u.all);
272 }
273
274 /* Only called for SRC manip */
275 static int
find_appropriate_src(struct net * net,const struct nf_conntrack_zone * zone,const struct nf_conntrack_tuple * tuple,struct nf_conntrack_tuple * result,const struct nf_nat_range2 * range)276 find_appropriate_src(struct net *net,
277 const struct nf_conntrack_zone *zone,
278 const struct nf_conntrack_tuple *tuple,
279 struct nf_conntrack_tuple *result,
280 const struct nf_nat_range2 *range)
281 {
282 unsigned int h = hash_by_src(net, zone, tuple);
283 const struct nf_conn *ct;
284
285 hlist_for_each_entry_rcu(ct, &nf_nat_bysource[h], nat_bysource) {
286 if (same_src(ct, tuple) &&
287 net_eq(net, nf_ct_net(ct)) &&
288 nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL)) {
289 /* Copy source part from reply tuple. */
290 nf_ct_invert_tuple(result,
291 &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
292 result->dst = tuple->dst;
293
294 if (in_range(result, range))
295 return 1;
296 }
297 }
298 return 0;
299 }
300
301 /* For [FUTURE] fragmentation handling, we want the least-used
302 * src-ip/dst-ip/proto triple. Fairness doesn't come into it. Thus
303 * if the range specifies 1.2.3.4 ports 10000-10005 and 1.2.3.5 ports
304 * 1-65535, we don't do pro-rata allocation based on ports; we choose
305 * the ip with the lowest src-ip/dst-ip/proto usage.
306 */
307 static void
find_best_ips_proto(const struct nf_conntrack_zone * zone,struct nf_conntrack_tuple * tuple,const struct nf_nat_range2 * range,const struct nf_conn * ct,enum nf_nat_manip_type maniptype)308 find_best_ips_proto(const struct nf_conntrack_zone *zone,
309 struct nf_conntrack_tuple *tuple,
310 const struct nf_nat_range2 *range,
311 const struct nf_conn *ct,
312 enum nf_nat_manip_type maniptype)
313 {
314 union nf_inet_addr *var_ipp;
315 unsigned int i, max;
316 /* Host order */
317 u32 minip, maxip, j, dist;
318 bool full_range;
319
320 /* No IP mapping? Do nothing. */
321 if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
322 return;
323
324 if (maniptype == NF_NAT_MANIP_SRC)
325 var_ipp = &tuple->src.u3;
326 else
327 var_ipp = &tuple->dst.u3;
328
329 /* Fast path: only one choice. */
330 if (nf_inet_addr_cmp(&range->min_addr, &range->max_addr)) {
331 *var_ipp = range->min_addr;
332 return;
333 }
334
335 if (nf_ct_l3num(ct) == NFPROTO_IPV4)
336 max = sizeof(var_ipp->ip) / sizeof(u32) - 1;
337 else
338 max = sizeof(var_ipp->ip6) / sizeof(u32) - 1;
339
340 /* Hashing source and destination IPs gives a fairly even
341 * spread in practice (if there are a small number of IPs
342 * involved, there usually aren't that many connections
343 * anyway). The consistency means that servers see the same
344 * client coming from the same IP (some Internet Banking sites
345 * like this), even across reboots.
346 */
347 j = jhash2((u32 *)&tuple->src.u3, sizeof(tuple->src.u3) / sizeof(u32),
348 range->flags & NF_NAT_RANGE_PERSISTENT ?
349 0 : (__force u32)tuple->dst.u3.all[max] ^ zone->id);
350
351 full_range = false;
352 for (i = 0; i <= max; i++) {
353 /* If first bytes of the address are at the maximum, use the
354 * distance. Otherwise use the full range.
355 */
356 if (!full_range) {
357 minip = ntohl((__force __be32)range->min_addr.all[i]);
358 maxip = ntohl((__force __be32)range->max_addr.all[i]);
359 dist = maxip - minip + 1;
360 } else {
361 minip = 0;
362 dist = ~0;
363 }
364
365 var_ipp->all[i] = (__force __u32)
366 htonl(minip + reciprocal_scale(j, dist));
367 if (var_ipp->all[i] != range->max_addr.all[i])
368 full_range = true;
369
370 if (!(range->flags & NF_NAT_RANGE_PERSISTENT))
371 j ^= (__force u32)tuple->dst.u3.all[i];
372 }
373 }
374
375 /* Alter the per-proto part of the tuple (depending on maniptype), to
376 * give a unique tuple in the given range if possible.
377 *
378 * Per-protocol part of tuple is initialized to the incoming packet.
379 */
nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple * tuple,const struct nf_nat_range2 * range,enum nf_nat_manip_type maniptype,const struct nf_conn * ct)380 static void nf_nat_l4proto_unique_tuple(struct nf_conntrack_tuple *tuple,
381 const struct nf_nat_range2 *range,
382 enum nf_nat_manip_type maniptype,
383 const struct nf_conn *ct)
384 {
385 unsigned int range_size, min, max, i, attempts;
386 __be16 *keyptr;
387 u16 off;
388 static const unsigned int max_attempts = 128;
389
390 switch (tuple->dst.protonum) {
391 case IPPROTO_ICMP:
392 case IPPROTO_ICMPV6:
393 /* id is same for either direction... */
394 keyptr = &tuple->src.u.icmp.id;
395 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
396 min = 0;
397 range_size = 65536;
398 } else {
399 min = ntohs(range->min_proto.icmp.id);
400 range_size = ntohs(range->max_proto.icmp.id) -
401 ntohs(range->min_proto.icmp.id) + 1;
402 }
403 goto find_free_id;
404 #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
405 case IPPROTO_GRE:
406 /* If there is no master conntrack we are not PPTP,
407 do not change tuples */
408 if (!ct->master)
409 return;
410
411 if (maniptype == NF_NAT_MANIP_SRC)
412 keyptr = &tuple->src.u.gre.key;
413 else
414 keyptr = &tuple->dst.u.gre.key;
415
416 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
417 min = 1;
418 range_size = 65535;
419 } else {
420 min = ntohs(range->min_proto.gre.key);
421 range_size = ntohs(range->max_proto.gre.key) - min + 1;
422 }
423 goto find_free_id;
424 #endif
425 case IPPROTO_UDP:
426 case IPPROTO_UDPLITE:
427 case IPPROTO_TCP:
428 case IPPROTO_SCTP:
429 case IPPROTO_DCCP:
430 if (maniptype == NF_NAT_MANIP_SRC)
431 keyptr = &tuple->src.u.all;
432 else
433 keyptr = &tuple->dst.u.all;
434
435 break;
436 default:
437 return;
438 }
439
440 /* If no range specified... */
441 if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)) {
442 /* If it's dst rewrite, can't change port */
443 if (maniptype == NF_NAT_MANIP_DST)
444 return;
445
446 if (ntohs(*keyptr) < 1024) {
447 /* Loose convention: >> 512 is credential passing */
448 if (ntohs(*keyptr) < 512) {
449 min = 1;
450 range_size = 511 - min + 1;
451 } else {
452 min = 600;
453 range_size = 1023 - min + 1;
454 }
455 } else {
456 min = 1024;
457 range_size = 65535 - 1024 + 1;
458 }
459 } else {
460 min = ntohs(range->min_proto.all);
461 max = ntohs(range->max_proto.all);
462 if (unlikely(max < min))
463 swap(max, min);
464 range_size = max - min + 1;
465 }
466
467 find_free_id:
468 if (range->flags & NF_NAT_RANGE_PROTO_OFFSET)
469 off = (ntohs(*keyptr) - ntohs(range->base_proto.all));
470 else
471 off = get_random_u16();
472
473 attempts = range_size;
474 if (attempts > max_attempts)
475 attempts = max_attempts;
476
477 /* We are in softirq; doing a search of the entire range risks
478 * soft lockup when all tuples are already used.
479 *
480 * If we can't find any free port from first offset, pick a new
481 * one and try again, with ever smaller search window.
482 */
483 another_round:
484 for (i = 0; i < attempts; i++, off++) {
485 *keyptr = htons(min + off % range_size);
486 if (!nf_nat_used_tuple(tuple, ct))
487 return;
488 }
489
490 if (attempts >= range_size || attempts < 16)
491 return;
492 attempts /= 2;
493 off = get_random_u16();
494 goto another_round;
495 }
496
497 /* Manipulate the tuple into the range given. For NF_INET_POST_ROUTING,
498 * we change the source to map into the range. For NF_INET_PRE_ROUTING
499 * and NF_INET_LOCAL_OUT, we change the destination to map into the
500 * range. It might not be possible to get a unique tuple, but we try.
501 * At worst (or if we race), we will end up with a final duplicate in
502 * __nf_conntrack_confirm and drop the packet. */
503 static void
get_unique_tuple(struct nf_conntrack_tuple * tuple,const struct nf_conntrack_tuple * orig_tuple,const struct nf_nat_range2 * range,struct nf_conn * ct,enum nf_nat_manip_type maniptype)504 get_unique_tuple(struct nf_conntrack_tuple *tuple,
505 const struct nf_conntrack_tuple *orig_tuple,
506 const struct nf_nat_range2 *range,
507 struct nf_conn *ct,
508 enum nf_nat_manip_type maniptype)
509 {
510 const struct nf_conntrack_zone *zone;
511 struct net *net = nf_ct_net(ct);
512
513 zone = nf_ct_zone(ct);
514
515 /* 1) If this srcip/proto/src-proto-part is currently mapped,
516 * and that same mapping gives a unique tuple within the given
517 * range, use that.
518 *
519 * This is only required for source (ie. NAT/masq) mappings.
520 * So far, we don't do local source mappings, so multiple
521 * manips not an issue.
522 */
523 if (maniptype == NF_NAT_MANIP_SRC &&
524 !(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
525 /* try the original tuple first */
526 if (in_range(orig_tuple, range)) {
527 if (!nf_nat_used_tuple(orig_tuple, ct)) {
528 *tuple = *orig_tuple;
529 return;
530 }
531 } else if (find_appropriate_src(net, zone,
532 orig_tuple, tuple, range)) {
533 pr_debug("get_unique_tuple: Found current src map\n");
534 if (!nf_nat_used_tuple(tuple, ct))
535 return;
536 }
537 }
538
539 /* 2) Select the least-used IP/proto combination in the given range */
540 *tuple = *orig_tuple;
541 find_best_ips_proto(zone, tuple, range, ct, maniptype);
542
543 /* 3) The per-protocol part of the manip is made to map into
544 * the range to make a unique tuple.
545 */
546
547 /* Only bother mapping if it's not already in range and unique */
548 if (!(range->flags & NF_NAT_RANGE_PROTO_RANDOM_ALL)) {
549 if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
550 if (!(range->flags & NF_NAT_RANGE_PROTO_OFFSET) &&
551 l4proto_in_range(tuple, maniptype,
552 &range->min_proto,
553 &range->max_proto) &&
554 (range->min_proto.all == range->max_proto.all ||
555 !nf_nat_used_tuple(tuple, ct)))
556 return;
557 } else if (!nf_nat_used_tuple(tuple, ct)) {
558 return;
559 }
560 }
561
562 /* Last chance: get protocol to try to obtain unique tuple. */
563 nf_nat_l4proto_unique_tuple(tuple, range, maniptype, ct);
564 }
565
nf_ct_nat_ext_add(struct nf_conn * ct)566 struct nf_conn_nat *nf_ct_nat_ext_add(struct nf_conn *ct)
567 {
568 struct nf_conn_nat *nat = nfct_nat(ct);
569 if (nat)
570 return nat;
571
572 if (!nf_ct_is_confirmed(ct))
573 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
574
575 return nat;
576 }
577 EXPORT_SYMBOL_GPL(nf_ct_nat_ext_add);
578
579 unsigned int
nf_nat_setup_info(struct nf_conn * ct,const struct nf_nat_range2 * range,enum nf_nat_manip_type maniptype)580 nf_nat_setup_info(struct nf_conn *ct,
581 const struct nf_nat_range2 *range,
582 enum nf_nat_manip_type maniptype)
583 {
584 struct net *net = nf_ct_net(ct);
585 struct nf_conntrack_tuple curr_tuple, new_tuple;
586
587 /* Can't setup nat info for confirmed ct. */
588 if (nf_ct_is_confirmed(ct))
589 return NF_ACCEPT;
590
591 WARN_ON(maniptype != NF_NAT_MANIP_SRC &&
592 maniptype != NF_NAT_MANIP_DST);
593
594 if (WARN_ON(nf_nat_initialized(ct, maniptype)))
595 return NF_DROP;
596
597 /* What we've got will look like inverse of reply. Normally
598 * this is what is in the conntrack, except for prior
599 * manipulations (future optimization: if num_manips == 0,
600 * orig_tp = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple)
601 */
602 nf_ct_invert_tuple(&curr_tuple,
603 &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
604
605 get_unique_tuple(&new_tuple, &curr_tuple, range, ct, maniptype);
606
607 if (!nf_ct_tuple_equal(&new_tuple, &curr_tuple)) {
608 struct nf_conntrack_tuple reply;
609
610 /* Alter conntrack table so will recognize replies. */
611 nf_ct_invert_tuple(&reply, &new_tuple);
612 nf_conntrack_alter_reply(ct, &reply);
613
614 /* Non-atomic: we own this at the moment. */
615 if (maniptype == NF_NAT_MANIP_SRC)
616 ct->status |= IPS_SRC_NAT;
617 else
618 ct->status |= IPS_DST_NAT;
619
620 if (nfct_help(ct) && !nfct_seqadj(ct))
621 if (!nfct_seqadj_ext_add(ct))
622 return NF_DROP;
623 }
624
625 if (maniptype == NF_NAT_MANIP_SRC) {
626 unsigned int srchash;
627 spinlock_t *lock;
628
629 srchash = hash_by_src(net, nf_ct_zone(ct),
630 &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
631 lock = &nf_nat_locks[srchash % CONNTRACK_LOCKS];
632 spin_lock_bh(lock);
633 hlist_add_head_rcu(&ct->nat_bysource,
634 &nf_nat_bysource[srchash]);
635 spin_unlock_bh(lock);
636 }
637
638 /* It's done. */
639 if (maniptype == NF_NAT_MANIP_DST)
640 ct->status |= IPS_DST_NAT_DONE;
641 else
642 ct->status |= IPS_SRC_NAT_DONE;
643
644 return NF_ACCEPT;
645 }
646 EXPORT_SYMBOL(nf_nat_setup_info);
647
648 static unsigned int
__nf_nat_alloc_null_binding(struct nf_conn * ct,enum nf_nat_manip_type manip)649 __nf_nat_alloc_null_binding(struct nf_conn *ct, enum nf_nat_manip_type manip)
650 {
651 /* Force range to this IP; let proto decide mapping for
652 * per-proto parts (hence not IP_NAT_RANGE_PROTO_SPECIFIED).
653 * Use reply in case it's already been mangled (eg local packet).
654 */
655 union nf_inet_addr ip =
656 (manip == NF_NAT_MANIP_SRC ?
657 ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3 :
658 ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3);
659 struct nf_nat_range2 range = {
660 .flags = NF_NAT_RANGE_MAP_IPS,
661 .min_addr = ip,
662 .max_addr = ip,
663 };
664 return nf_nat_setup_info(ct, &range, manip);
665 }
666
667 unsigned int
nf_nat_alloc_null_binding(struct nf_conn * ct,unsigned int hooknum)668 nf_nat_alloc_null_binding(struct nf_conn *ct, unsigned int hooknum)
669 {
670 return __nf_nat_alloc_null_binding(ct, HOOK2MANIP(hooknum));
671 }
672 EXPORT_SYMBOL_GPL(nf_nat_alloc_null_binding);
673
674 /* Do packet manipulations according to nf_nat_setup_info. */
nf_nat_packet(struct nf_conn * ct,enum ip_conntrack_info ctinfo,unsigned int hooknum,struct sk_buff * skb)675 unsigned int nf_nat_packet(struct nf_conn *ct,
676 enum ip_conntrack_info ctinfo,
677 unsigned int hooknum,
678 struct sk_buff *skb)
679 {
680 enum nf_nat_manip_type mtype = HOOK2MANIP(hooknum);
681 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
682 unsigned int verdict = NF_ACCEPT;
683 unsigned long statusbit;
684
685 if (mtype == NF_NAT_MANIP_SRC)
686 statusbit = IPS_SRC_NAT;
687 else
688 statusbit = IPS_DST_NAT;
689
690 /* Invert if this is reply dir. */
691 if (dir == IP_CT_DIR_REPLY)
692 statusbit ^= IPS_NAT_MASK;
693
694 /* Non-atomic: these bits don't change. */
695 if (ct->status & statusbit)
696 verdict = nf_nat_manip_pkt(skb, ct, mtype, dir);
697
698 return verdict;
699 }
700 EXPORT_SYMBOL_GPL(nf_nat_packet);
701
in_vrf_postrouting(const struct nf_hook_state * state)702 static bool in_vrf_postrouting(const struct nf_hook_state *state)
703 {
704 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
705 if (state->hook == NF_INET_POST_ROUTING &&
706 netif_is_l3_master(state->out))
707 return true;
708 #endif
709 return false;
710 }
711
712 unsigned int
nf_nat_inet_fn(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)713 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
714 const struct nf_hook_state *state)
715 {
716 struct nf_conn *ct;
717 enum ip_conntrack_info ctinfo;
718 struct nf_conn_nat *nat;
719 /* maniptype == SRC for postrouting. */
720 enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
721
722 ct = nf_ct_get(skb, &ctinfo);
723 /* Can't track? It's not due to stress, or conntrack would
724 * have dropped it. Hence it's the user's responsibilty to
725 * packet filter it out, or implement conntrack/NAT for that
726 * protocol. 8) --RR
727 */
728 if (!ct || in_vrf_postrouting(state))
729 return NF_ACCEPT;
730
731 nat = nfct_nat(ct);
732
733 switch (ctinfo) {
734 case IP_CT_RELATED:
735 case IP_CT_RELATED_REPLY:
736 /* Only ICMPs can be IP_CT_IS_REPLY. Fallthrough */
737 case IP_CT_NEW:
738 /* Seen it before? This can happen for loopback, retrans,
739 * or local packets.
740 */
741 if (!nf_nat_initialized(ct, maniptype)) {
742 struct nf_nat_lookup_hook_priv *lpriv = priv;
743 struct nf_hook_entries *e = rcu_dereference(lpriv->entries);
744 unsigned int ret;
745 int i;
746
747 if (!e)
748 goto null_bind;
749
750 for (i = 0; i < e->num_hook_entries; i++) {
751 ret = e->hooks[i].hook(e->hooks[i].priv, skb,
752 state);
753 if (ret != NF_ACCEPT)
754 return ret;
755 if (nf_nat_initialized(ct, maniptype))
756 goto do_nat;
757 }
758 null_bind:
759 ret = nf_nat_alloc_null_binding(ct, state->hook);
760 if (ret != NF_ACCEPT)
761 return ret;
762 } else {
763 pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n",
764 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
765 ct, ct->status);
766 if (nf_nat_oif_changed(state->hook, ctinfo, nat,
767 state->out))
768 goto oif_changed;
769 }
770 break;
771 default:
772 /* ESTABLISHED */
773 WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
774 ctinfo != IP_CT_ESTABLISHED_REPLY);
775 if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
776 goto oif_changed;
777 }
778 do_nat:
779 return nf_nat_packet(ct, ctinfo, state->hook, skb);
780
781 oif_changed:
782 nf_ct_kill_acct(ct, ctinfo, skb);
783 return NF_DROP;
784 }
785 EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
786
787 struct nf_nat_proto_clean {
788 u8 l3proto;
789 u8 l4proto;
790 };
791
792 /* kill conntracks with affected NAT section */
nf_nat_proto_remove(struct nf_conn * i,void * data)793 static int nf_nat_proto_remove(struct nf_conn *i, void *data)
794 {
795 const struct nf_nat_proto_clean *clean = data;
796
797 if ((clean->l3proto && nf_ct_l3num(i) != clean->l3proto) ||
798 (clean->l4proto && nf_ct_protonum(i) != clean->l4proto))
799 return 0;
800
801 return i->status & IPS_NAT_MASK ? 1 : 0;
802 }
803
nf_nat_cleanup_conntrack(struct nf_conn * ct)804 static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
805 {
806 unsigned int h;
807
808 h = hash_by_src(nf_ct_net(ct), nf_ct_zone(ct), &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
809 spin_lock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
810 hlist_del_rcu(&ct->nat_bysource);
811 spin_unlock_bh(&nf_nat_locks[h % CONNTRACK_LOCKS]);
812 }
813
nf_nat_proto_clean(struct nf_conn * ct,void * data)814 static int nf_nat_proto_clean(struct nf_conn *ct, void *data)
815 {
816 if (nf_nat_proto_remove(ct, data))
817 return 1;
818
819 /* This module is being removed and conntrack has nat null binding.
820 * Remove it from bysource hash, as the table will be freed soon.
821 *
822 * Else, when the conntrack is destoyed, nf_nat_cleanup_conntrack()
823 * will delete entry from already-freed table.
824 */
825 if (test_and_clear_bit(IPS_SRC_NAT_DONE_BIT, &ct->status))
826 nf_nat_cleanup_conntrack(ct);
827
828 /* don't delete conntrack. Although that would make things a lot
829 * simpler, we'd end up flushing all conntracks on nat rmmod.
830 */
831 return 0;
832 }
833
834 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
835
836 #include <linux/netfilter/nfnetlink.h>
837 #include <linux/netfilter/nfnetlink_conntrack.h>
838
839 static const struct nla_policy protonat_nla_policy[CTA_PROTONAT_MAX+1] = {
840 [CTA_PROTONAT_PORT_MIN] = { .type = NLA_U16 },
841 [CTA_PROTONAT_PORT_MAX] = { .type = NLA_U16 },
842 };
843
nf_nat_l4proto_nlattr_to_range(struct nlattr * tb[],struct nf_nat_range2 * range)844 static int nf_nat_l4proto_nlattr_to_range(struct nlattr *tb[],
845 struct nf_nat_range2 *range)
846 {
847 if (tb[CTA_PROTONAT_PORT_MIN]) {
848 range->min_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MIN]);
849 range->max_proto.all = range->min_proto.all;
850 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
851 }
852 if (tb[CTA_PROTONAT_PORT_MAX]) {
853 range->max_proto.all = nla_get_be16(tb[CTA_PROTONAT_PORT_MAX]);
854 range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
855 }
856 return 0;
857 }
858
nfnetlink_parse_nat_proto(struct nlattr * attr,const struct nf_conn * ct,struct nf_nat_range2 * range)859 static int nfnetlink_parse_nat_proto(struct nlattr *attr,
860 const struct nf_conn *ct,
861 struct nf_nat_range2 *range)
862 {
863 struct nlattr *tb[CTA_PROTONAT_MAX+1];
864 int err;
865
866 err = nla_parse_nested_deprecated(tb, CTA_PROTONAT_MAX, attr,
867 protonat_nla_policy, NULL);
868 if (err < 0)
869 return err;
870
871 return nf_nat_l4proto_nlattr_to_range(tb, range);
872 }
873
874 static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
875 [CTA_NAT_V4_MINIP] = { .type = NLA_U32 },
876 [CTA_NAT_V4_MAXIP] = { .type = NLA_U32 },
877 [CTA_NAT_V6_MINIP] = { .len = sizeof(struct in6_addr) },
878 [CTA_NAT_V6_MAXIP] = { .len = sizeof(struct in6_addr) },
879 [CTA_NAT_PROTO] = { .type = NLA_NESTED },
880 };
881
nf_nat_ipv4_nlattr_to_range(struct nlattr * tb[],struct nf_nat_range2 * range)882 static int nf_nat_ipv4_nlattr_to_range(struct nlattr *tb[],
883 struct nf_nat_range2 *range)
884 {
885 if (tb[CTA_NAT_V4_MINIP]) {
886 range->min_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MINIP]);
887 range->flags |= NF_NAT_RANGE_MAP_IPS;
888 }
889
890 if (tb[CTA_NAT_V4_MAXIP])
891 range->max_addr.ip = nla_get_be32(tb[CTA_NAT_V4_MAXIP]);
892 else
893 range->max_addr.ip = range->min_addr.ip;
894
895 return 0;
896 }
897
nf_nat_ipv6_nlattr_to_range(struct nlattr * tb[],struct nf_nat_range2 * range)898 static int nf_nat_ipv6_nlattr_to_range(struct nlattr *tb[],
899 struct nf_nat_range2 *range)
900 {
901 if (tb[CTA_NAT_V6_MINIP]) {
902 nla_memcpy(&range->min_addr.ip6, tb[CTA_NAT_V6_MINIP],
903 sizeof(struct in6_addr));
904 range->flags |= NF_NAT_RANGE_MAP_IPS;
905 }
906
907 if (tb[CTA_NAT_V6_MAXIP])
908 nla_memcpy(&range->max_addr.ip6, tb[CTA_NAT_V6_MAXIP],
909 sizeof(struct in6_addr));
910 else
911 range->max_addr = range->min_addr;
912
913 return 0;
914 }
915
916 static int
nfnetlink_parse_nat(const struct nlattr * nat,const struct nf_conn * ct,struct nf_nat_range2 * range)917 nfnetlink_parse_nat(const struct nlattr *nat,
918 const struct nf_conn *ct, struct nf_nat_range2 *range)
919 {
920 struct nlattr *tb[CTA_NAT_MAX+1];
921 int err;
922
923 memset(range, 0, sizeof(*range));
924
925 err = nla_parse_nested_deprecated(tb, CTA_NAT_MAX, nat,
926 nat_nla_policy, NULL);
927 if (err < 0)
928 return err;
929
930 switch (nf_ct_l3num(ct)) {
931 case NFPROTO_IPV4:
932 err = nf_nat_ipv4_nlattr_to_range(tb, range);
933 break;
934 case NFPROTO_IPV6:
935 err = nf_nat_ipv6_nlattr_to_range(tb, range);
936 break;
937 default:
938 err = -EPROTONOSUPPORT;
939 break;
940 }
941
942 if (err)
943 return err;
944
945 if (!tb[CTA_NAT_PROTO])
946 return 0;
947
948 return nfnetlink_parse_nat_proto(tb[CTA_NAT_PROTO], ct, range);
949 }
950
951 /* This function is called under rcu_read_lock() */
952 static int
nfnetlink_parse_nat_setup(struct nf_conn * ct,enum nf_nat_manip_type manip,const struct nlattr * attr)953 nfnetlink_parse_nat_setup(struct nf_conn *ct,
954 enum nf_nat_manip_type manip,
955 const struct nlattr *attr)
956 {
957 struct nf_nat_range2 range;
958 int err;
959
960 /* Should not happen, restricted to creating new conntracks
961 * via ctnetlink.
962 */
963 if (WARN_ON_ONCE(nf_nat_initialized(ct, manip)))
964 return -EEXIST;
965
966 /* No NAT information has been passed, allocate the null-binding */
967 if (attr == NULL)
968 return __nf_nat_alloc_null_binding(ct, manip) == NF_DROP ? -ENOMEM : 0;
969
970 err = nfnetlink_parse_nat(attr, ct, &range);
971 if (err < 0)
972 return err;
973
974 return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0;
975 }
976 #else
977 static int
nfnetlink_parse_nat_setup(struct nf_conn * ct,enum nf_nat_manip_type manip,const struct nlattr * attr)978 nfnetlink_parse_nat_setup(struct nf_conn *ct,
979 enum nf_nat_manip_type manip,
980 const struct nlattr *attr)
981 {
982 return -EOPNOTSUPP;
983 }
984 #endif
985
986 static struct nf_ct_helper_expectfn follow_master_nat = {
987 .name = "nat-follow-master",
988 .expectfn = nf_nat_follow_master,
989 };
990
nf_nat_register_fn(struct net * net,u8 pf,const struct nf_hook_ops * ops,const struct nf_hook_ops * orig_nat_ops,unsigned int ops_count)991 int nf_nat_register_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
992 const struct nf_hook_ops *orig_nat_ops, unsigned int ops_count)
993 {
994 struct nat_net *nat_net = net_generic(net, nat_net_id);
995 struct nf_nat_hooks_net *nat_proto_net;
996 struct nf_nat_lookup_hook_priv *priv;
997 unsigned int hooknum = ops->hooknum;
998 struct nf_hook_ops *nat_ops;
999 int i, ret;
1000
1001 if (WARN_ON_ONCE(pf >= ARRAY_SIZE(nat_net->nat_proto_net)))
1002 return -EINVAL;
1003
1004 nat_proto_net = &nat_net->nat_proto_net[pf];
1005
1006 for (i = 0; i < ops_count; i++) {
1007 if (orig_nat_ops[i].hooknum == hooknum) {
1008 hooknum = i;
1009 break;
1010 }
1011 }
1012
1013 if (WARN_ON_ONCE(i == ops_count))
1014 return -EINVAL;
1015
1016 mutex_lock(&nf_nat_proto_mutex);
1017 if (!nat_proto_net->nat_hook_ops) {
1018 WARN_ON(nat_proto_net->users != 0);
1019
1020 nat_ops = kmemdup(orig_nat_ops, sizeof(*orig_nat_ops) * ops_count, GFP_KERNEL);
1021 if (!nat_ops) {
1022 mutex_unlock(&nf_nat_proto_mutex);
1023 return -ENOMEM;
1024 }
1025
1026 for (i = 0; i < ops_count; i++) {
1027 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
1028 if (priv) {
1029 nat_ops[i].priv = priv;
1030 continue;
1031 }
1032 mutex_unlock(&nf_nat_proto_mutex);
1033 while (i)
1034 kfree(nat_ops[--i].priv);
1035 kfree(nat_ops);
1036 return -ENOMEM;
1037 }
1038
1039 ret = nf_register_net_hooks(net, nat_ops, ops_count);
1040 if (ret < 0) {
1041 mutex_unlock(&nf_nat_proto_mutex);
1042 for (i = 0; i < ops_count; i++)
1043 kfree(nat_ops[i].priv);
1044 kfree(nat_ops);
1045 return ret;
1046 }
1047
1048 nat_proto_net->nat_hook_ops = nat_ops;
1049 }
1050
1051 nat_ops = nat_proto_net->nat_hook_ops;
1052 priv = nat_ops[hooknum].priv;
1053 if (WARN_ON_ONCE(!priv)) {
1054 mutex_unlock(&nf_nat_proto_mutex);
1055 return -EOPNOTSUPP;
1056 }
1057
1058 ret = nf_hook_entries_insert_raw(&priv->entries, ops);
1059 if (ret == 0)
1060 nat_proto_net->users++;
1061
1062 mutex_unlock(&nf_nat_proto_mutex);
1063 return ret;
1064 }
1065
nf_nat_unregister_fn(struct net * net,u8 pf,const struct nf_hook_ops * ops,unsigned int ops_count)1066 void nf_nat_unregister_fn(struct net *net, u8 pf, const struct nf_hook_ops *ops,
1067 unsigned int ops_count)
1068 {
1069 struct nat_net *nat_net = net_generic(net, nat_net_id);
1070 struct nf_nat_hooks_net *nat_proto_net;
1071 struct nf_nat_lookup_hook_priv *priv;
1072 struct nf_hook_ops *nat_ops;
1073 int hooknum = ops->hooknum;
1074 int i;
1075
1076 if (pf >= ARRAY_SIZE(nat_net->nat_proto_net))
1077 return;
1078
1079 nat_proto_net = &nat_net->nat_proto_net[pf];
1080
1081 mutex_lock(&nf_nat_proto_mutex);
1082 if (WARN_ON(nat_proto_net->users == 0))
1083 goto unlock;
1084
1085 nat_proto_net->users--;
1086
1087 nat_ops = nat_proto_net->nat_hook_ops;
1088 for (i = 0; i < ops_count; i++) {
1089 if (nat_ops[i].hooknum == hooknum) {
1090 hooknum = i;
1091 break;
1092 }
1093 }
1094 if (WARN_ON_ONCE(i == ops_count))
1095 goto unlock;
1096 priv = nat_ops[hooknum].priv;
1097 nf_hook_entries_delete_raw(&priv->entries, ops);
1098
1099 if (nat_proto_net->users == 0) {
1100 nf_unregister_net_hooks(net, nat_ops, ops_count);
1101
1102 for (i = 0; i < ops_count; i++) {
1103 priv = nat_ops[i].priv;
1104 kfree_rcu(priv, rcu_head);
1105 }
1106
1107 nat_proto_net->nat_hook_ops = NULL;
1108 kfree(nat_ops);
1109 }
1110 unlock:
1111 mutex_unlock(&nf_nat_proto_mutex);
1112 }
1113
1114 static struct pernet_operations nat_net_ops = {
1115 .id = &nat_net_id,
1116 .size = sizeof(struct nat_net),
1117 };
1118
1119 static const struct nf_nat_hook nat_hook = {
1120 .parse_nat_setup = nfnetlink_parse_nat_setup,
1121 #ifdef CONFIG_XFRM
1122 .decode_session = __nf_nat_decode_session,
1123 #endif
1124 .manip_pkt = nf_nat_manip_pkt,
1125 .remove_nat_bysrc = nf_nat_cleanup_conntrack,
1126 };
1127
nf_nat_init(void)1128 static int __init nf_nat_init(void)
1129 {
1130 int ret, i;
1131
1132 /* Leave them the same for the moment. */
1133 nf_nat_htable_size = nf_conntrack_htable_size;
1134 if (nf_nat_htable_size < CONNTRACK_LOCKS)
1135 nf_nat_htable_size = CONNTRACK_LOCKS;
1136
1137 nf_nat_bysource = nf_ct_alloc_hashtable(&nf_nat_htable_size, 0);
1138 if (!nf_nat_bysource)
1139 return -ENOMEM;
1140
1141 for (i = 0; i < CONNTRACK_LOCKS; i++)
1142 spin_lock_init(&nf_nat_locks[i]);
1143
1144 ret = register_pernet_subsys(&nat_net_ops);
1145 if (ret < 0) {
1146 kvfree(nf_nat_bysource);
1147 return ret;
1148 }
1149
1150 nf_ct_helper_expectfn_register(&follow_master_nat);
1151
1152 WARN_ON(nf_nat_hook != NULL);
1153 RCU_INIT_POINTER(nf_nat_hook, &nat_hook);
1154
1155 ret = register_nf_nat_bpf();
1156 if (ret < 0) {
1157 RCU_INIT_POINTER(nf_nat_hook, NULL);
1158 nf_ct_helper_expectfn_unregister(&follow_master_nat);
1159 synchronize_net();
1160 unregister_pernet_subsys(&nat_net_ops);
1161 kvfree(nf_nat_bysource);
1162 }
1163
1164 return ret;
1165 }
1166
nf_nat_cleanup(void)1167 static void __exit nf_nat_cleanup(void)
1168 {
1169 struct nf_nat_proto_clean clean = {};
1170
1171 nf_ct_iterate_destroy(nf_nat_proto_clean, &clean);
1172
1173 nf_ct_helper_expectfn_unregister(&follow_master_nat);
1174 RCU_INIT_POINTER(nf_nat_hook, NULL);
1175
1176 synchronize_net();
1177 kvfree(nf_nat_bysource);
1178 unregister_pernet_subsys(&nat_net_ops);
1179 }
1180
1181 MODULE_LICENSE("GPL");
1182
1183 module_init(nf_nat_init);
1184 module_exit(nf_nat_cleanup);
1185