This source file includes following definitions.
- __udp_manip_pkt
- udp_manip_pkt
- udplite_manip_pkt
- sctp_manip_pkt
- tcp_manip_pkt
- dccp_manip_pkt
- icmp_manip_pkt
- icmpv6_manip_pkt
- gre_manip_pkt
- l4proto_manip_pkt
- nf_nat_ipv4_manip_pkt
- nf_nat_ipv6_manip_pkt
- nf_nat_manip_pkt
- nf_nat_ipv4_csum_update
- nf_nat_ipv6_csum_update
- nf_csum_update
- nf_nat_ipv4_csum_recalc
- nf_nat_ipv6_csum_recalc
- nf_nat_csum_recalc
- nf_nat_icmp_reply_translation
- nf_nat_ipv4_fn
- nf_nat_ipv4_in
- nf_nat_ipv4_out
- nf_nat_ipv4_local_fn
- nf_nat_ipv4_register_fn
- nf_nat_ipv4_unregister_fn
- nf_nat_icmpv6_reply_translation
- nf_nat_ipv6_fn
- nf_nat_ipv6_in
- nf_nat_ipv6_out
- nf_nat_ipv6_local_fn
- nf_nat_ipv6_register_fn
- nf_nat_ipv6_unregister_fn
- nf_nat_inet_register_fn
- nf_nat_inet_unregister_fn
1
2
3
4
5
6 #include <linux/types.h>
7 #include <linux/export.h>
8 #include <linux/init.h>
9 #include <linux/udp.h>
10 #include <linux/tcp.h>
11 #include <linux/icmp.h>
12 #include <linux/icmpv6.h>
13
14 #include <linux/dccp.h>
15 #include <linux/sctp.h>
16 #include <net/sctp/checksum.h>
17
18 #include <linux/netfilter.h>
19 #include <net/netfilter/nf_nat.h>
20
21 #include <linux/ipv6.h>
22 #include <linux/netfilter_ipv6.h>
23 #include <net/checksum.h>
24 #include <net/ip6_checksum.h>
25 #include <net/ip6_route.h>
26 #include <net/xfrm.h>
27 #include <net/ipv6.h>
28
29 #include <net/netfilter/nf_conntrack_core.h>
30 #include <net/netfilter/nf_conntrack.h>
31 #include <linux/netfilter/nfnetlink_conntrack.h>
32
33 static void nf_csum_update(struct sk_buff *skb,
34 unsigned int iphdroff, __sum16 *check,
35 const struct nf_conntrack_tuple *t,
36 enum nf_nat_manip_type maniptype);
37
38 static void
39 __udp_manip_pkt(struct sk_buff *skb,
40 unsigned int iphdroff, struct udphdr *hdr,
41 const struct nf_conntrack_tuple *tuple,
42 enum nf_nat_manip_type maniptype, bool do_csum)
43 {
44 __be16 *portptr, newport;
45
46 if (maniptype == NF_NAT_MANIP_SRC) {
47
48 newport = tuple->src.u.udp.port;
49 portptr = &hdr->source;
50 } else {
51
52 newport = tuple->dst.u.udp.port;
53 portptr = &hdr->dest;
54 }
55 if (do_csum) {
56 nf_csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
57 inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport,
58 false);
59 if (!hdr->check)
60 hdr->check = CSUM_MANGLED_0;
61 }
62 *portptr = newport;
63 }
64
65 static bool udp_manip_pkt(struct sk_buff *skb,
66 unsigned int iphdroff, unsigned int hdroff,
67 const struct nf_conntrack_tuple *tuple,
68 enum nf_nat_manip_type maniptype)
69 {
70 struct udphdr *hdr;
71
72 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
73 return false;
74
75 hdr = (struct udphdr *)(skb->data + hdroff);
76 __udp_manip_pkt(skb, iphdroff, hdr, tuple, maniptype, !!hdr->check);
77
78 return true;
79 }
80
81 static bool udplite_manip_pkt(struct sk_buff *skb,
82 unsigned int iphdroff, unsigned int hdroff,
83 const struct nf_conntrack_tuple *tuple,
84 enum nf_nat_manip_type maniptype)
85 {
86 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
87 struct udphdr *hdr;
88
89 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
90 return false;
91
92 hdr = (struct udphdr *)(skb->data + hdroff);
93 __udp_manip_pkt(skb, iphdroff, hdr, tuple, maniptype, true);
94 #endif
95 return true;
96 }
97
98 static bool
99 sctp_manip_pkt(struct sk_buff *skb,
100 unsigned int iphdroff, unsigned int hdroff,
101 const struct nf_conntrack_tuple *tuple,
102 enum nf_nat_manip_type maniptype)
103 {
104 #ifdef CONFIG_NF_CT_PROTO_SCTP
105 struct sctphdr *hdr;
106 int hdrsize = 8;
107
108
109
110
111
112 if (skb->len >= hdroff + sizeof(*hdr))
113 hdrsize = sizeof(*hdr);
114
115 if (skb_ensure_writable(skb, hdroff + hdrsize))
116 return false;
117
118 hdr = (struct sctphdr *)(skb->data + hdroff);
119
120 if (maniptype == NF_NAT_MANIP_SRC) {
121
122 hdr->source = tuple->src.u.sctp.port;
123 } else {
124
125 hdr->dest = tuple->dst.u.sctp.port;
126 }
127
128 if (hdrsize < sizeof(*hdr))
129 return true;
130
131 if (skb->ip_summed != CHECKSUM_PARTIAL) {
132 hdr->checksum = sctp_compute_cksum(skb, hdroff);
133 skb->ip_summed = CHECKSUM_NONE;
134 }
135
136 #endif
137 return true;
138 }
139
140 static bool
141 tcp_manip_pkt(struct sk_buff *skb,
142 unsigned int iphdroff, unsigned int hdroff,
143 const struct nf_conntrack_tuple *tuple,
144 enum nf_nat_manip_type maniptype)
145 {
146 struct tcphdr *hdr;
147 __be16 *portptr, newport, oldport;
148 int hdrsize = 8;
149
150
151
152
153 if (skb->len >= hdroff + sizeof(struct tcphdr))
154 hdrsize = sizeof(struct tcphdr);
155
156 if (skb_ensure_writable(skb, hdroff + hdrsize))
157 return false;
158
159 hdr = (struct tcphdr *)(skb->data + hdroff);
160
161 if (maniptype == NF_NAT_MANIP_SRC) {
162
163 newport = tuple->src.u.tcp.port;
164 portptr = &hdr->source;
165 } else {
166
167 newport = tuple->dst.u.tcp.port;
168 portptr = &hdr->dest;
169 }
170
171 oldport = *portptr;
172 *portptr = newport;
173
174 if (hdrsize < sizeof(*hdr))
175 return true;
176
177 nf_csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
178 inet_proto_csum_replace2(&hdr->check, skb, oldport, newport, false);
179 return true;
180 }
181
182 static bool
183 dccp_manip_pkt(struct sk_buff *skb,
184 unsigned int iphdroff, unsigned int hdroff,
185 const struct nf_conntrack_tuple *tuple,
186 enum nf_nat_manip_type maniptype)
187 {
188 #ifdef CONFIG_NF_CT_PROTO_DCCP
189 struct dccp_hdr *hdr;
190 __be16 *portptr, oldport, newport;
191 int hdrsize = 8;
192
193 if (skb->len >= hdroff + sizeof(struct dccp_hdr))
194 hdrsize = sizeof(struct dccp_hdr);
195
196 if (skb_ensure_writable(skb, hdroff + hdrsize))
197 return false;
198
199 hdr = (struct dccp_hdr *)(skb->data + hdroff);
200
201 if (maniptype == NF_NAT_MANIP_SRC) {
202 newport = tuple->src.u.dccp.port;
203 portptr = &hdr->dccph_sport;
204 } else {
205 newport = tuple->dst.u.dccp.port;
206 portptr = &hdr->dccph_dport;
207 }
208
209 oldport = *portptr;
210 *portptr = newport;
211
212 if (hdrsize < sizeof(*hdr))
213 return true;
214
215 nf_csum_update(skb, iphdroff, &hdr->dccph_checksum, tuple, maniptype);
216 inet_proto_csum_replace2(&hdr->dccph_checksum, skb, oldport, newport,
217 false);
218 #endif
219 return true;
220 }
221
222 static bool
223 icmp_manip_pkt(struct sk_buff *skb,
224 unsigned int iphdroff, unsigned int hdroff,
225 const struct nf_conntrack_tuple *tuple,
226 enum nf_nat_manip_type maniptype)
227 {
228 struct icmphdr *hdr;
229
230 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
231 return false;
232
233 hdr = (struct icmphdr *)(skb->data + hdroff);
234 switch (hdr->type) {
235 case ICMP_ECHO:
236 case ICMP_ECHOREPLY:
237 case ICMP_TIMESTAMP:
238 case ICMP_TIMESTAMPREPLY:
239 case ICMP_INFO_REQUEST:
240 case ICMP_INFO_REPLY:
241 case ICMP_ADDRESS:
242 case ICMP_ADDRESSREPLY:
243 break;
244 default:
245 return true;
246 }
247 inet_proto_csum_replace2(&hdr->checksum, skb,
248 hdr->un.echo.id, tuple->src.u.icmp.id, false);
249 hdr->un.echo.id = tuple->src.u.icmp.id;
250 return true;
251 }
252
253 static bool
254 icmpv6_manip_pkt(struct sk_buff *skb,
255 unsigned int iphdroff, unsigned int hdroff,
256 const struct nf_conntrack_tuple *tuple,
257 enum nf_nat_manip_type maniptype)
258 {
259 struct icmp6hdr *hdr;
260
261 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
262 return false;
263
264 hdr = (struct icmp6hdr *)(skb->data + hdroff);
265 nf_csum_update(skb, iphdroff, &hdr->icmp6_cksum, tuple, maniptype);
266 if (hdr->icmp6_type == ICMPV6_ECHO_REQUEST ||
267 hdr->icmp6_type == ICMPV6_ECHO_REPLY) {
268 inet_proto_csum_replace2(&hdr->icmp6_cksum, skb,
269 hdr->icmp6_identifier,
270 tuple->src.u.icmp.id, false);
271 hdr->icmp6_identifier = tuple->src.u.icmp.id;
272 }
273 return true;
274 }
275
276
277 static bool
278 gre_manip_pkt(struct sk_buff *skb,
279 unsigned int iphdroff, unsigned int hdroff,
280 const struct nf_conntrack_tuple *tuple,
281 enum nf_nat_manip_type maniptype)
282 {
283 #if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
284 const struct gre_base_hdr *greh;
285 struct pptp_gre_header *pgreh;
286
287
288
289 if (skb_ensure_writable(skb, hdroff + sizeof(*pgreh) - 8))
290 return false;
291
292 greh = (void *)skb->data + hdroff;
293 pgreh = (struct pptp_gre_header *)greh;
294
295
296
297 if (maniptype != NF_NAT_MANIP_DST)
298 return true;
299
300 switch (greh->flags & GRE_VERSION) {
301 case GRE_VERSION_0:
302
303
304 break;
305 case GRE_VERSION_1:
306 pr_debug("call_id -> 0x%04x\n", ntohs(tuple->dst.u.gre.key));
307 pgreh->call_id = tuple->dst.u.gre.key;
308 break;
309 default:
310 pr_debug("can't nat unknown GRE version\n");
311 return false;
312 }
313 #endif
314 return true;
315 }
316
317 static bool l4proto_manip_pkt(struct sk_buff *skb,
318 unsigned int iphdroff, unsigned int hdroff,
319 const struct nf_conntrack_tuple *tuple,
320 enum nf_nat_manip_type maniptype)
321 {
322 switch (tuple->dst.protonum) {
323 case IPPROTO_TCP:
324 return tcp_manip_pkt(skb, iphdroff, hdroff,
325 tuple, maniptype);
326 case IPPROTO_UDP:
327 return udp_manip_pkt(skb, iphdroff, hdroff,
328 tuple, maniptype);
329 case IPPROTO_UDPLITE:
330 return udplite_manip_pkt(skb, iphdroff, hdroff,
331 tuple, maniptype);
332 case IPPROTO_SCTP:
333 return sctp_manip_pkt(skb, iphdroff, hdroff,
334 tuple, maniptype);
335 case IPPROTO_ICMP:
336 return icmp_manip_pkt(skb, iphdroff, hdroff,
337 tuple, maniptype);
338 case IPPROTO_ICMPV6:
339 return icmpv6_manip_pkt(skb, iphdroff, hdroff,
340 tuple, maniptype);
341 case IPPROTO_DCCP:
342 return dccp_manip_pkt(skb, iphdroff, hdroff,
343 tuple, maniptype);
344 case IPPROTO_GRE:
345 return gre_manip_pkt(skb, iphdroff, hdroff,
346 tuple, maniptype);
347 }
348
349
350 return true;
351 }
352
353 static bool nf_nat_ipv4_manip_pkt(struct sk_buff *skb,
354 unsigned int iphdroff,
355 const struct nf_conntrack_tuple *target,
356 enum nf_nat_manip_type maniptype)
357 {
358 struct iphdr *iph;
359 unsigned int hdroff;
360
361 if (skb_ensure_writable(skb, iphdroff + sizeof(*iph)))
362 return false;
363
364 iph = (void *)skb->data + iphdroff;
365 hdroff = iphdroff + iph->ihl * 4;
366
367 if (!l4proto_manip_pkt(skb, iphdroff, hdroff, target, maniptype))
368 return false;
369 iph = (void *)skb->data + iphdroff;
370
371 if (maniptype == NF_NAT_MANIP_SRC) {
372 csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
373 iph->saddr = target->src.u3.ip;
374 } else {
375 csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
376 iph->daddr = target->dst.u3.ip;
377 }
378 return true;
379 }
380
381 static bool nf_nat_ipv6_manip_pkt(struct sk_buff *skb,
382 unsigned int iphdroff,
383 const struct nf_conntrack_tuple *target,
384 enum nf_nat_manip_type maniptype)
385 {
386 #if IS_ENABLED(CONFIG_IPV6)
387 struct ipv6hdr *ipv6h;
388 __be16 frag_off;
389 int hdroff;
390 u8 nexthdr;
391
392 if (skb_ensure_writable(skb, iphdroff + sizeof(*ipv6h)))
393 return false;
394
395 ipv6h = (void *)skb->data + iphdroff;
396 nexthdr = ipv6h->nexthdr;
397 hdroff = ipv6_skip_exthdr(skb, iphdroff + sizeof(*ipv6h),
398 &nexthdr, &frag_off);
399 if (hdroff < 0)
400 goto manip_addr;
401
402 if ((frag_off & htons(~0x7)) == 0 &&
403 !l4proto_manip_pkt(skb, iphdroff, hdroff, target, maniptype))
404 return false;
405
406
407 ipv6h = (void *)skb->data + iphdroff;
408
409 manip_addr:
410 if (maniptype == NF_NAT_MANIP_SRC)
411 ipv6h->saddr = target->src.u3.in6;
412 else
413 ipv6h->daddr = target->dst.u3.in6;
414
415 #endif
416 return true;
417 }
418
419 unsigned int nf_nat_manip_pkt(struct sk_buff *skb, struct nf_conn *ct,
420 enum nf_nat_manip_type mtype,
421 enum ip_conntrack_dir dir)
422 {
423 struct nf_conntrack_tuple target;
424
425
426 nf_ct_invert_tuple(&target, &ct->tuplehash[!dir].tuple);
427
428 switch (target.src.l3num) {
429 case NFPROTO_IPV6:
430 if (nf_nat_ipv6_manip_pkt(skb, 0, &target, mtype))
431 return NF_ACCEPT;
432 break;
433 case NFPROTO_IPV4:
434 if (nf_nat_ipv4_manip_pkt(skb, 0, &target, mtype))
435 return NF_ACCEPT;
436 break;
437 default:
438 WARN_ON_ONCE(1);
439 break;
440 }
441
442 return NF_DROP;
443 }
444
445 static void nf_nat_ipv4_csum_update(struct sk_buff *skb,
446 unsigned int iphdroff, __sum16 *check,
447 const struct nf_conntrack_tuple *t,
448 enum nf_nat_manip_type maniptype)
449 {
450 struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
451 __be32 oldip, newip;
452
453 if (maniptype == NF_NAT_MANIP_SRC) {
454 oldip = iph->saddr;
455 newip = t->src.u3.ip;
456 } else {
457 oldip = iph->daddr;
458 newip = t->dst.u3.ip;
459 }
460 inet_proto_csum_replace4(check, skb, oldip, newip, true);
461 }
462
463 static void nf_nat_ipv6_csum_update(struct sk_buff *skb,
464 unsigned int iphdroff, __sum16 *check,
465 const struct nf_conntrack_tuple *t,
466 enum nf_nat_manip_type maniptype)
467 {
468 #if IS_ENABLED(CONFIG_IPV6)
469 const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + iphdroff);
470 const struct in6_addr *oldip, *newip;
471
472 if (maniptype == NF_NAT_MANIP_SRC) {
473 oldip = &ipv6h->saddr;
474 newip = &t->src.u3.in6;
475 } else {
476 oldip = &ipv6h->daddr;
477 newip = &t->dst.u3.in6;
478 }
479 inet_proto_csum_replace16(check, skb, oldip->s6_addr32,
480 newip->s6_addr32, true);
481 #endif
482 }
483
484 static void nf_csum_update(struct sk_buff *skb,
485 unsigned int iphdroff, __sum16 *check,
486 const struct nf_conntrack_tuple *t,
487 enum nf_nat_manip_type maniptype)
488 {
489 switch (t->src.l3num) {
490 case NFPROTO_IPV4:
491 nf_nat_ipv4_csum_update(skb, iphdroff, check, t, maniptype);
492 return;
493 case NFPROTO_IPV6:
494 nf_nat_ipv6_csum_update(skb, iphdroff, check, t, maniptype);
495 return;
496 }
497 }
498
499 static void nf_nat_ipv4_csum_recalc(struct sk_buff *skb,
500 u8 proto, void *data, __sum16 *check,
501 int datalen, int oldlen)
502 {
503 if (skb->ip_summed != CHECKSUM_PARTIAL) {
504 const struct iphdr *iph = ip_hdr(skb);
505
506 skb->ip_summed = CHECKSUM_PARTIAL;
507 skb->csum_start = skb_headroom(skb) + skb_network_offset(skb) +
508 ip_hdrlen(skb);
509 skb->csum_offset = (void *)check - data;
510 *check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
511 proto, 0);
512 } else {
513 inet_proto_csum_replace2(check, skb,
514 htons(oldlen), htons(datalen), true);
515 }
516 }
517
518 #if IS_ENABLED(CONFIG_IPV6)
519 static void nf_nat_ipv6_csum_recalc(struct sk_buff *skb,
520 u8 proto, void *data, __sum16 *check,
521 int datalen, int oldlen)
522 {
523 if (skb->ip_summed != CHECKSUM_PARTIAL) {
524 const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
525
526 skb->ip_summed = CHECKSUM_PARTIAL;
527 skb->csum_start = skb_headroom(skb) + skb_network_offset(skb) +
528 (data - (void *)skb->data);
529 skb->csum_offset = (void *)check - data;
530 *check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
531 datalen, proto, 0);
532 } else {
533 inet_proto_csum_replace2(check, skb,
534 htons(oldlen), htons(datalen), true);
535 }
536 }
537 #endif
538
539 void nf_nat_csum_recalc(struct sk_buff *skb,
540 u8 nfproto, u8 proto, void *data, __sum16 *check,
541 int datalen, int oldlen)
542 {
543 switch (nfproto) {
544 case NFPROTO_IPV4:
545 nf_nat_ipv4_csum_recalc(skb, proto, data, check,
546 datalen, oldlen);
547 return;
548 #if IS_ENABLED(CONFIG_IPV6)
549 case NFPROTO_IPV6:
550 nf_nat_ipv6_csum_recalc(skb, proto, data, check,
551 datalen, oldlen);
552 return;
553 #endif
554 }
555
556 WARN_ON_ONCE(1);
557 }
558
559 int nf_nat_icmp_reply_translation(struct sk_buff *skb,
560 struct nf_conn *ct,
561 enum ip_conntrack_info ctinfo,
562 unsigned int hooknum)
563 {
564 struct {
565 struct icmphdr icmp;
566 struct iphdr ip;
567 } *inside;
568 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
569 enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
570 unsigned int hdrlen = ip_hdrlen(skb);
571 struct nf_conntrack_tuple target;
572 unsigned long statusbit;
573
574 WARN_ON(ctinfo != IP_CT_RELATED && ctinfo != IP_CT_RELATED_REPLY);
575
576 if (skb_ensure_writable(skb, hdrlen + sizeof(*inside)))
577 return 0;
578 if (nf_ip_checksum(skb, hooknum, hdrlen, IPPROTO_ICMP))
579 return 0;
580
581 inside = (void *)skb->data + hdrlen;
582 if (inside->icmp.type == ICMP_REDIRECT) {
583 if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
584 return 0;
585 if (ct->status & IPS_NAT_MASK)
586 return 0;
587 }
588
589 if (manip == NF_NAT_MANIP_SRC)
590 statusbit = IPS_SRC_NAT;
591 else
592 statusbit = IPS_DST_NAT;
593
594
595 if (dir == IP_CT_DIR_REPLY)
596 statusbit ^= IPS_NAT_MASK;
597
598 if (!(ct->status & statusbit))
599 return 1;
600
601 if (!nf_nat_ipv4_manip_pkt(skb, hdrlen + sizeof(inside->icmp),
602 &ct->tuplehash[!dir].tuple, !manip))
603 return 0;
604
605 if (skb->ip_summed != CHECKSUM_PARTIAL) {
606
607 inside = (void *)skb->data + hdrlen;
608 inside->icmp.checksum = 0;
609 inside->icmp.checksum =
610 csum_fold(skb_checksum(skb, hdrlen,
611 skb->len - hdrlen, 0));
612 }
613
614
615 nf_ct_invert_tuple(&target, &ct->tuplehash[!dir].tuple);
616 target.dst.protonum = IPPROTO_ICMP;
617 if (!nf_nat_ipv4_manip_pkt(skb, 0, &target, manip))
618 return 0;
619
620 return 1;
621 }
622 EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);
623
624 static unsigned int
625 nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
626 const struct nf_hook_state *state)
627 {
628 struct nf_conn *ct;
629 enum ip_conntrack_info ctinfo;
630
631 ct = nf_ct_get(skb, &ctinfo);
632 if (!ct)
633 return NF_ACCEPT;
634
635 if (ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY) {
636 if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
637 if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
638 state->hook))
639 return NF_DROP;
640 else
641 return NF_ACCEPT;
642 }
643 }
644
645 return nf_nat_inet_fn(priv, skb, state);
646 }
647
648 static unsigned int
649 nf_nat_ipv4_in(void *priv, struct sk_buff *skb,
650 const struct nf_hook_state *state)
651 {
652 unsigned int ret;
653 __be32 daddr = ip_hdr(skb)->daddr;
654
655 ret = nf_nat_ipv4_fn(priv, skb, state);
656 if (ret == NF_ACCEPT && daddr != ip_hdr(skb)->daddr)
657 skb_dst_drop(skb);
658
659 return ret;
660 }
661
662 static unsigned int
663 nf_nat_ipv4_out(void *priv, struct sk_buff *skb,
664 const struct nf_hook_state *state)
665 {
666 #ifdef CONFIG_XFRM
667 const struct nf_conn *ct;
668 enum ip_conntrack_info ctinfo;
669 int err;
670 #endif
671 unsigned int ret;
672
673 ret = nf_nat_ipv4_fn(priv, skb, state);
674 #ifdef CONFIG_XFRM
675 if (ret != NF_ACCEPT)
676 return ret;
677
678 if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
679 return ret;
680
681 ct = nf_ct_get(skb, &ctinfo);
682 if (ct) {
683 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
684
685 if (ct->tuplehash[dir].tuple.src.u3.ip !=
686 ct->tuplehash[!dir].tuple.dst.u3.ip ||
687 (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
688 ct->tuplehash[dir].tuple.src.u.all !=
689 ct->tuplehash[!dir].tuple.dst.u.all)) {
690 err = nf_xfrm_me_harder(state->net, skb, AF_INET);
691 if (err < 0)
692 ret = NF_DROP_ERR(err);
693 }
694 }
695 #endif
696 return ret;
697 }
698
699 static unsigned int
700 nf_nat_ipv4_local_fn(void *priv, struct sk_buff *skb,
701 const struct nf_hook_state *state)
702 {
703 const struct nf_conn *ct;
704 enum ip_conntrack_info ctinfo;
705 unsigned int ret;
706 int err;
707
708 ret = nf_nat_ipv4_fn(priv, skb, state);
709 if (ret != NF_ACCEPT)
710 return ret;
711
712 ct = nf_ct_get(skb, &ctinfo);
713 if (ct) {
714 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
715
716 if (ct->tuplehash[dir].tuple.dst.u3.ip !=
717 ct->tuplehash[!dir].tuple.src.u3.ip) {
718 err = ip_route_me_harder(state->net, skb, RTN_UNSPEC);
719 if (err < 0)
720 ret = NF_DROP_ERR(err);
721 }
722 #ifdef CONFIG_XFRM
723 else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
724 ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
725 ct->tuplehash[dir].tuple.dst.u.all !=
726 ct->tuplehash[!dir].tuple.src.u.all) {
727 err = nf_xfrm_me_harder(state->net, skb, AF_INET);
728 if (err < 0)
729 ret = NF_DROP_ERR(err);
730 }
731 #endif
732 }
733 return ret;
734 }
735
736 static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
737
738 {
739 .hook = nf_nat_ipv4_in,
740 .pf = NFPROTO_IPV4,
741 .hooknum = NF_INET_PRE_ROUTING,
742 .priority = NF_IP_PRI_NAT_DST,
743 },
744
745 {
746 .hook = nf_nat_ipv4_out,
747 .pf = NFPROTO_IPV4,
748 .hooknum = NF_INET_POST_ROUTING,
749 .priority = NF_IP_PRI_NAT_SRC,
750 },
751
752 {
753 .hook = nf_nat_ipv4_local_fn,
754 .pf = NFPROTO_IPV4,
755 .hooknum = NF_INET_LOCAL_OUT,
756 .priority = NF_IP_PRI_NAT_DST,
757 },
758
759 {
760 .hook = nf_nat_ipv4_fn,
761 .pf = NFPROTO_IPV4,
762 .hooknum = NF_INET_LOCAL_IN,
763 .priority = NF_IP_PRI_NAT_SRC,
764 },
765 };
766
767 int nf_nat_ipv4_register_fn(struct net *net, const struct nf_hook_ops *ops)
768 {
769 return nf_nat_register_fn(net, ops->pf, ops, nf_nat_ipv4_ops,
770 ARRAY_SIZE(nf_nat_ipv4_ops));
771 }
772 EXPORT_SYMBOL_GPL(nf_nat_ipv4_register_fn);
773
774 void nf_nat_ipv4_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
775 {
776 nf_nat_unregister_fn(net, ops->pf, ops, ARRAY_SIZE(nf_nat_ipv4_ops));
777 }
778 EXPORT_SYMBOL_GPL(nf_nat_ipv4_unregister_fn);
779
780 #if IS_ENABLED(CONFIG_IPV6)
781 int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,
782 struct nf_conn *ct,
783 enum ip_conntrack_info ctinfo,
784 unsigned int hooknum,
785 unsigned int hdrlen)
786 {
787 struct {
788 struct icmp6hdr icmp6;
789 struct ipv6hdr ip6;
790 } *inside;
791 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
792 enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
793 struct nf_conntrack_tuple target;
794 unsigned long statusbit;
795
796 WARN_ON(ctinfo != IP_CT_RELATED && ctinfo != IP_CT_RELATED_REPLY);
797
798 if (skb_ensure_writable(skb, hdrlen + sizeof(*inside)))
799 return 0;
800 if (nf_ip6_checksum(skb, hooknum, hdrlen, IPPROTO_ICMPV6))
801 return 0;
802
803 inside = (void *)skb->data + hdrlen;
804 if (inside->icmp6.icmp6_type == NDISC_REDIRECT) {
805 if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
806 return 0;
807 if (ct->status & IPS_NAT_MASK)
808 return 0;
809 }
810
811 if (manip == NF_NAT_MANIP_SRC)
812 statusbit = IPS_SRC_NAT;
813 else
814 statusbit = IPS_DST_NAT;
815
816
817 if (dir == IP_CT_DIR_REPLY)
818 statusbit ^= IPS_NAT_MASK;
819
820 if (!(ct->status & statusbit))
821 return 1;
822
823 if (!nf_nat_ipv6_manip_pkt(skb, hdrlen + sizeof(inside->icmp6),
824 &ct->tuplehash[!dir].tuple, !manip))
825 return 0;
826
827 if (skb->ip_summed != CHECKSUM_PARTIAL) {
828 struct ipv6hdr *ipv6h = ipv6_hdr(skb);
829
830 inside = (void *)skb->data + hdrlen;
831 inside->icmp6.icmp6_cksum = 0;
832 inside->icmp6.icmp6_cksum =
833 csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
834 skb->len - hdrlen, IPPROTO_ICMPV6,
835 skb_checksum(skb, hdrlen,
836 skb->len - hdrlen, 0));
837 }
838
839 nf_ct_invert_tuple(&target, &ct->tuplehash[!dir].tuple);
840 target.dst.protonum = IPPROTO_ICMPV6;
841 if (!nf_nat_ipv6_manip_pkt(skb, 0, &target, manip))
842 return 0;
843
844 return 1;
845 }
846 EXPORT_SYMBOL_GPL(nf_nat_icmpv6_reply_translation);
847
848 static unsigned int
849 nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
850 const struct nf_hook_state *state)
851 {
852 struct nf_conn *ct;
853 enum ip_conntrack_info ctinfo;
854 __be16 frag_off;
855 int hdrlen;
856 u8 nexthdr;
857
858 ct = nf_ct_get(skb, &ctinfo);
859
860
861
862
863
864 if (!ct)
865 return NF_ACCEPT;
866
867 if (ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY) {
868 nexthdr = ipv6_hdr(skb)->nexthdr;
869 hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
870 &nexthdr, &frag_off);
871
872 if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
873 if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
874 state->hook,
875 hdrlen))
876 return NF_DROP;
877 else
878 return NF_ACCEPT;
879 }
880 }
881
882 return nf_nat_inet_fn(priv, skb, state);
883 }
884
885 static unsigned int
886 nf_nat_ipv6_in(void *priv, struct sk_buff *skb,
887 const struct nf_hook_state *state)
888 {
889 unsigned int ret;
890 struct in6_addr daddr = ipv6_hdr(skb)->daddr;
891
892 ret = nf_nat_ipv6_fn(priv, skb, state);
893 if (ret != NF_DROP && ret != NF_STOLEN &&
894 ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
895 skb_dst_drop(skb);
896
897 return ret;
898 }
899
900 static unsigned int
901 nf_nat_ipv6_out(void *priv, struct sk_buff *skb,
902 const struct nf_hook_state *state)
903 {
904 #ifdef CONFIG_XFRM
905 const struct nf_conn *ct;
906 enum ip_conntrack_info ctinfo;
907 int err;
908 #endif
909 unsigned int ret;
910
911 ret = nf_nat_ipv6_fn(priv, skb, state);
912 #ifdef CONFIG_XFRM
913 if (ret != NF_ACCEPT)
914 return ret;
915
916 if (IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED)
917 return ret;
918 ct = nf_ct_get(skb, &ctinfo);
919 if (ct) {
920 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
921
922 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
923 &ct->tuplehash[!dir].tuple.dst.u3) ||
924 (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
925 ct->tuplehash[dir].tuple.src.u.all !=
926 ct->tuplehash[!dir].tuple.dst.u.all)) {
927 err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
928 if (err < 0)
929 ret = NF_DROP_ERR(err);
930 }
931 }
932 #endif
933
934 return ret;
935 }
936
937 static unsigned int
938 nf_nat_ipv6_local_fn(void *priv, struct sk_buff *skb,
939 const struct nf_hook_state *state)
940 {
941 const struct nf_conn *ct;
942 enum ip_conntrack_info ctinfo;
943 unsigned int ret;
944 int err;
945
946 ret = nf_nat_ipv6_fn(priv, skb, state);
947 if (ret != NF_ACCEPT)
948 return ret;
949
950 ct = nf_ct_get(skb, &ctinfo);
951 if (ct) {
952 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
953
954 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
955 &ct->tuplehash[!dir].tuple.src.u3)) {
956 err = nf_ip6_route_me_harder(state->net, skb);
957 if (err < 0)
958 ret = NF_DROP_ERR(err);
959 }
960 #ifdef CONFIG_XFRM
961 else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
962 ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
963 ct->tuplehash[dir].tuple.dst.u.all !=
964 ct->tuplehash[!dir].tuple.src.u.all) {
965 err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
966 if (err < 0)
967 ret = NF_DROP_ERR(err);
968 }
969 #endif
970 }
971
972 return ret;
973 }
974
975 static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
976
977 {
978 .hook = nf_nat_ipv6_in,
979 .pf = NFPROTO_IPV6,
980 .hooknum = NF_INET_PRE_ROUTING,
981 .priority = NF_IP6_PRI_NAT_DST,
982 },
983
984 {
985 .hook = nf_nat_ipv6_out,
986 .pf = NFPROTO_IPV6,
987 .hooknum = NF_INET_POST_ROUTING,
988 .priority = NF_IP6_PRI_NAT_SRC,
989 },
990
991 {
992 .hook = nf_nat_ipv6_local_fn,
993 .pf = NFPROTO_IPV6,
994 .hooknum = NF_INET_LOCAL_OUT,
995 .priority = NF_IP6_PRI_NAT_DST,
996 },
997
998 {
999 .hook = nf_nat_ipv6_fn,
1000 .pf = NFPROTO_IPV6,
1001 .hooknum = NF_INET_LOCAL_IN,
1002 .priority = NF_IP6_PRI_NAT_SRC,
1003 },
1004 };
1005
1006 int nf_nat_ipv6_register_fn(struct net *net, const struct nf_hook_ops *ops)
1007 {
1008 return nf_nat_register_fn(net, ops->pf, ops, nf_nat_ipv6_ops,
1009 ARRAY_SIZE(nf_nat_ipv6_ops));
1010 }
1011 EXPORT_SYMBOL_GPL(nf_nat_ipv6_register_fn);
1012
1013 void nf_nat_ipv6_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
1014 {
1015 nf_nat_unregister_fn(net, ops->pf, ops, ARRAY_SIZE(nf_nat_ipv6_ops));
1016 }
1017 EXPORT_SYMBOL_GPL(nf_nat_ipv6_unregister_fn);
1018 #endif
1019
1020 #if defined(CONFIG_NF_TABLES_INET) && IS_ENABLED(CONFIG_NFT_NAT)
1021 int nf_nat_inet_register_fn(struct net *net, const struct nf_hook_ops *ops)
1022 {
1023 int ret;
1024
1025 if (WARN_ON_ONCE(ops->pf != NFPROTO_INET))
1026 return -EINVAL;
1027
1028 ret = nf_nat_register_fn(net, NFPROTO_IPV6, ops, nf_nat_ipv6_ops,
1029 ARRAY_SIZE(nf_nat_ipv6_ops));
1030 if (ret)
1031 return ret;
1032
1033 ret = nf_nat_register_fn(net, NFPROTO_IPV4, ops, nf_nat_ipv4_ops,
1034 ARRAY_SIZE(nf_nat_ipv4_ops));
1035 if (ret)
1036 nf_nat_unregister_fn(net, NFPROTO_IPV6, ops,
1037 ARRAY_SIZE(nf_nat_ipv6_ops));
1038 return ret;
1039 }
1040 EXPORT_SYMBOL_GPL(nf_nat_inet_register_fn);
1041
1042 void nf_nat_inet_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
1043 {
1044 nf_nat_unregister_fn(net, NFPROTO_IPV4, ops, ARRAY_SIZE(nf_nat_ipv4_ops));
1045 nf_nat_unregister_fn(net, NFPROTO_IPV6, ops, ARRAY_SIZE(nf_nat_ipv6_ops));
1046 }
1047 EXPORT_SYMBOL_GPL(nf_nat_inet_unregister_fn);
1048 #endif