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Merge tag 'io_uring-5.7-2020-05-22' of git://git.kernel.dk/linux-block
[thirdparty/linux.git] / net / netfilter / nf_nat_proto.c
CommitLineData
d2912cb1 1// SPDX-License-Identifier: GPL-2.0-only
faec18db
FW		 2/* (C) 1999-2001 Paul `Rusty' Russell
3 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
faec18db
FW		 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>
faec18db 20
3bf195ae
FW		 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>
14cb1a6e 31#include <linux/netfilter/nfnetlink_conntrack.h>
3bf195ae 32
03fe5efc
FW		 33static 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
faec18db
FW		 38static void
39__udp_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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 /* Get rid of src port */
48 newport = tuple->src.u.udp.port;
49 portptr = &hdr->source;
50 } else {
51 /* Get rid of dst port */
52 newport = tuple->dst.u.udp.port;
53 portptr = &hdr->dest;
54 }
55 if (do_csum) {
03fe5efc 56 nf_csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
faec18db
FW		 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
65static bool udp_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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;
faec18db 71
86f04538 72 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
faec18db
FW		 73 return false;
74
75 hdr = (struct udphdr *)(skb->data + hdroff);
ea64d8d6 76 __udp_manip_pkt(skb, iphdroff, hdr, tuple, maniptype, !!hdr->check);
faec18db 77
faec18db
FW		 78 return true;
79}
80
81static bool udplite_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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
86f04538 89 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
faec18db
FW		 90 return false;
91
92 hdr = (struct udphdr *)(skb->data + hdroff);
03fe5efc 93 __udp_manip_pkt(skb, iphdroff, hdr, tuple, maniptype, true);
faec18db
FW		 94#endif
95 return true;
96}
97
98static bool
99sctp_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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 /* This could be an inner header returned in imcp packet; in such
109 * cases we cannot update the checksum field since it is outside
110 * of the 8 bytes of transport layer headers we are guaranteed.
111 */
112 if (skb->len >= hdroff + sizeof(*hdr))
113 hdrsize = sizeof(*hdr);
114
86f04538 115 if (skb_ensure_writable(skb, hdroff + hdrsize))
faec18db
FW		 116 return false;
117
118 hdr = (struct sctphdr *)(skb->data + hdroff);
119
120 if (maniptype == NF_NAT_MANIP_SRC) {
121 /* Get rid of src port */
122 hdr->source = tuple->src.u.sctp.port;
123 } else {
124 /* Get rid of dst port */
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
140static bool
141tcp_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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; /* TCP connection tracking guarantees this much */
149
150 /* this could be a inner header returned in icmp packet; in such
151 cases we cannot update the checksum field since it is outside of
152 the 8 bytes of transport layer headers we are guaranteed */
153 if (skb->len >= hdroff + sizeof(struct tcphdr))
154 hdrsize = sizeof(struct tcphdr);
155
86f04538 156 if (skb_ensure_writable(skb, hdroff + hdrsize))
faec18db
FW		 157 return false;
158
159 hdr = (struct tcphdr *)(skb->data + hdroff);
160
161 if (maniptype == NF_NAT_MANIP_SRC) {
162 /* Get rid of src port */
163 newport = tuple->src.u.tcp.port;
164 portptr = &hdr->source;
165 } else {
166 /* Get rid of dst port */
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
03fe5efc 177 nf_csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
faec18db
FW		 178 inet_proto_csum_replace2(&hdr->check, skb, oldport, newport, false);
179 return true;
180}
181
182static bool
183dccp_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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; /* DCCP connection tracking guarantees this much */
192
193 if (skb->len >= hdroff + sizeof(struct dccp_hdr))
194 hdrsize = sizeof(struct dccp_hdr);
195
86f04538 196 if (skb_ensure_writable(skb, hdroff + hdrsize))
faec18db
FW		 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
03fe5efc 215 nf_csum_update(skb, iphdroff, &hdr->dccph_checksum, tuple, maniptype);
faec18db
FW		 216 inet_proto_csum_replace2(&hdr->dccph_checksum, skb, oldport, newport,
217 false);
218#endif
219 return true;
220}
221
222static bool
223icmp_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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
86f04538 230 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
faec18db
FW		 231 return false;
232
233 hdr = (struct icmphdr *)(skb->data + hdroff);
61177e91
EB		 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 }
faec18db
FW		 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
253static bool
254icmpv6_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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
86f04538 261 if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
faec18db
FW		 262 return false;
263
264 hdr = (struct icmp6hdr *)(skb->data + hdroff);
03fe5efc 265 nf_csum_update(skb, iphdroff, &hdr->icmp6_cksum, tuple, maniptype);
faec18db
FW		 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/* manipulate a GRE packet according to maniptype */
277static bool
278gre_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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 /* pgreh includes two optional 32bit fields which are not required
288 * to be there. That's where the magic '8' comes from */
86f04538 289 if (skb_ensure_writable(skb, hdroff + sizeof(*pgreh) - 8))
faec18db
FW		 290 return false;
291
292 greh = (void *)skb->data + hdroff;
293 pgreh = (struct pptp_gre_header *)greh;
294
295 /* we only have destination manip of a packet, since 'source key'
296 * is not present in the packet itself */
297 if (maniptype != NF_NAT_MANIP_DST)
298 return true;
299
300 switch (greh->flags & GRE_VERSION) {
301 case GRE_VERSION_0:
302 /* We do not currently NAT any GREv0 packets.
303 * Try to behave like "nf_nat_proto_unknown" */
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
14cb1a6e 317static bool l4proto_manip_pkt(struct sk_buff *skb,
faec18db
FW		 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:
03fe5efc 324 return tcp_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 325 tuple, maniptype);
326 case IPPROTO_UDP:
03fe5efc 327 return udp_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 328 tuple, maniptype);
329 case IPPROTO_UDPLITE:
03fe5efc 330 return udplite_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 331 tuple, maniptype);
332 case IPPROTO_SCTP:
03fe5efc 333 return sctp_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 334 tuple, maniptype);
335 case IPPROTO_ICMP:
03fe5efc 336 return icmp_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 337 tuple, maniptype);
338 case IPPROTO_ICMPV6:
03fe5efc 339 return icmpv6_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 340 tuple, maniptype);
341 case IPPROTO_DCCP:
03fe5efc 342 return dccp_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 343 tuple, maniptype);
344 case IPPROTO_GRE:
03fe5efc 345 return gre_manip_pkt(skb, iphdroff, hdroff,
faec18db
FW		 346 tuple, maniptype);
347 }
348
349 /* If we don't know protocol -- no error, pass it unmodified. */
350 return true;
351}
3bf195ae
FW		 352
353static 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
86f04538 361 if (skb_ensure_writable(skb, iphdroff + sizeof(*iph)))
3bf195ae
FW		 362 return false;
363
364 iph = (void *)skb->data + iphdroff;
365 hdroff = iphdroff + iph->ihl * 4;
366
03fe5efc 367 if (!l4proto_manip_pkt(skb, iphdroff, hdroff, target, maniptype))
3bf195ae
FW		 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
381static 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
86f04538 392 if (skb_ensure_writable(skb, iphdroff + sizeof(*ipv6h)))
3bf195ae
FW		 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 &&
03fe5efc 403 !l4proto_manip_pkt(skb, iphdroff, hdroff, target, maniptype))
3bf195ae
FW		 404 return false;
405
406 /* must reload, offset might have changed */
407 ipv6h = (void *)skb->data + iphdroff;
408
409manip_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
2e666b22
FW		 419unsigned 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 /* We are aiming to look like inverse of other direction. */
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
3bf195ae
FW		 445static 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
463static 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
03fe5efc
FW		 484static 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
3bf195ae
FW		 499static 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)
519static 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
dac3fe72
FW		 539void 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
3bf195ae
FW		 559int 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
86f04538 576 if (skb_ensure_writable(skb, hdrlen + sizeof(*inside)))
3bf195ae 577 return 0;
5d154984 578 if (nf_ip_checksum(skb, hooknum, hdrlen, IPPROTO_ICMP))
3bf195ae
FW		 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 /* Invert if this is reply direction */
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 /* Reloading "inside" here since manip_pkt may reallocate */
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 /* Change outer to look like the reply to an incoming packet */
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}
622EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);
623
624static unsigned int
625nf_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
648static unsigned int
649nf_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
662static unsigned int
663nf_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
699static unsigned int
700nf_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
0a30ba50 736static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
3bf195ae
FW		 737 /* Before packet filtering, change destination */
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 /* After packet filtering, change source */
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 /* Before packet filtering, change destination */
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 /* After packet filtering, change source */
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
d2c5c103 767int nf_nat_ipv4_register_fn(struct net *net, const struct nf_hook_ops *ops)
3bf195ae 768{
d164385e
FW		 769 return nf_nat_register_fn(net, ops->pf, ops, nf_nat_ipv4_ops,
770 ARRAY_SIZE(nf_nat_ipv4_ops));
3bf195ae 771}
d2c5c103 772EXPORT_SYMBOL_GPL(nf_nat_ipv4_register_fn);
3bf195ae 773
d2c5c103 774void nf_nat_ipv4_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
3bf195ae 775{
d164385e 776 nf_nat_unregister_fn(net, ops->pf, ops, ARRAY_SIZE(nf_nat_ipv4_ops));
3bf195ae 777}
d2c5c103 778EXPORT_SYMBOL_GPL(nf_nat_ipv4_unregister_fn);
3bf195ae 779
3bf195ae 780#if IS_ENABLED(CONFIG_IPV6)
3bf195ae
FW		 781int 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
86f04538 798 if (skb_ensure_writable(skb, hdrlen + sizeof(*inside)))
3bf195ae
FW		 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 /* Invert if this is reply direction */
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}
846EXPORT_SYMBOL_GPL(nf_nat_icmpv6_reply_translation);
847
848static unsigned int
849nf_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 /* Can't track? It's not due to stress, or conntrack would
860 * have dropped it. Hence it's the user's responsibilty to
861 * packet filter it out, or implement conntrack/NAT for that
862 * protocol. 8) --RR
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
885static unsigned int
886nf_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
900static unsigned int
901nf_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
3bf195ae
FW		 937static unsigned int
938nf_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)) {
c1deb065 956 err = nf_ip6_route_me_harder(state->net, skb);
3bf195ae
FW		 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
0a30ba50 975static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
3bf195ae
FW		 976 /* Before packet filtering, change destination */
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 /* After packet filtering, change source */
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 /* Before packet filtering, change destination */
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 /* After packet filtering, change source */
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
d2c5c103 1006int nf_nat_ipv6_register_fn(struct net *net, const struct nf_hook_ops *ops)
3bf195ae 1007{
d164385e 1008 return nf_nat_register_fn(net, ops->pf, ops, nf_nat_ipv6_ops,
3bf195ae
FW		 1009 ARRAY_SIZE(nf_nat_ipv6_ops));
1010}
d2c5c103 1011EXPORT_SYMBOL_GPL(nf_nat_ipv6_register_fn);
3bf195ae 1012
d2c5c103 1013void nf_nat_ipv6_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
3bf195ae 1014{
d164385e 1015 nf_nat_unregister_fn(net, ops->pf, ops, ARRAY_SIZE(nf_nat_ipv6_ops));
3bf195ae 1016}
d2c5c103 1017EXPORT_SYMBOL_GPL(nf_nat_ipv6_unregister_fn);
3bf195ae 1018#endif /* CONFIG_IPV6 */
d164385e
FW		 1019
1020#if defined(CONFIG_NF_TABLES_INET) && IS_ENABLED(CONFIG_NFT_NAT)
1021int 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)
b4faef17
HD		 1036 nf_nat_unregister_fn(net, NFPROTO_IPV6, ops,
1037 ARRAY_SIZE(nf_nat_ipv6_ops));
d164385e
FW		 1038 return ret;
1039}
1040EXPORT_SYMBOL_GPL(nf_nat_inet_register_fn);
1041
1042void 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}
1047EXPORT_SYMBOL_GPL(nf_nat_inet_unregister_fn);
1048#endif /* NFT INET NAT */
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