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CVE-2018-14629 dns: fix CNAME loop prevention using counter regression
[Samba.git] / source4 / dns_server / dns_query.c
blobb75fabe7e827591ada313365509991db9c773a70
1 /*
2 Unix SMB/CIFS implementation.
3
4 DNS server handler for queries
5
6 Copyright (C) 2010 Kai Blin <kai@samba.org>
7
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
12
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
17
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 */
21
22 #include "includes.h"
23 #include "smbd/service_task.h"
24 #include "libcli/util/werror.h"
25 #include "librpc/ndr/libndr.h"
26 #include "librpc/gen_ndr/ndr_dns.h"
27 #include "librpc/gen_ndr/ndr_dnsp.h"
28 #include <ldb.h>
29 #include "param/param.h"
30 #include "dsdb/samdb/samdb.h"
31 #include "dsdb/common/util.h"
32 #include "dns_server/dns_server.h"
33 #include "libcli/dns/libdns.h"
34 #include "lib/util/dlinklist.h"
35 #include "lib/util/util_net.h"
36 #include "lib/util/tevent_werror.h"
37 #include "auth/auth.h"
38 #include "auth/credentials/credentials.h"
39 #include "auth/gensec/gensec.h"
40
41 #undef DBGC_CLASS
42 #define DBGC_CLASS DBGC_DNS
43 #define MAX_Q_RECURSION_DEPTH 20
44
45 struct forwarder_string {
46 const char *forwarder;
47 struct forwarder_string *prev, *next;
48 };
49
50 static WERROR add_response_rr(const char *name,
51 const struct dnsp_DnssrvRpcRecord *rec,
52 struct dns_res_rec **answers)
53 {
54 struct dns_res_rec *ans = *answers;
55 uint16_t ai = talloc_array_length(ans);
56 enum ndr_err_code ndr_err;
57
58 if (ai == UINT16_MAX) {
59 return WERR_BUFFER_OVERFLOW;
60 }
61
62 /*
63 * "ans" is always non-NULL and thus its own talloc context
64 */
65 ans = talloc_realloc(ans, ans, struct dns_res_rec, ai+1);
66 if (ans == NULL) {
67 return WERR_NOT_ENOUGH_MEMORY;
68 }
69
70 ZERO_STRUCT(ans[ai]);
71
72 switch (rec->wType) {
73 case DNS_QTYPE_CNAME:
74 ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
75 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.cname_record);
76 break;
77 case DNS_QTYPE_A:
78 ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
79 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv4_record);
80 break;
81 case DNS_QTYPE_AAAA:
82 ans[ai].rdata.ipv6_record = talloc_strdup(ans, rec->data.ipv6);
83 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv6_record);
84 break;
85 case DNS_TYPE_NS:
86 ans[ai].rdata.ns_record = talloc_strdup(ans, rec->data.ns);
87 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ns_record);
88 break;
89 case DNS_QTYPE_SRV:
90 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
91 ans[ai].rdata.srv_record.weight = rec->data.srv.wWeight;
92 ans[ai].rdata.srv_record.port = rec->data.srv.wPort;
93 ans[ai].rdata.srv_record.target = talloc_strdup(
94 ans, rec->data.srv.nameTarget);
95 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.srv_record.target);
96 break;
97 case DNS_QTYPE_SOA:
98 ans[ai].rdata.soa_record.mname = talloc_strdup(
99 ans, rec->data.soa.mname);
100 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.mname);
101 ans[ai].rdata.soa_record.rname = talloc_strdup(
102 ans, rec->data.soa.rname);
103 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.rname);
104 ans[ai].rdata.soa_record.serial = rec->data.soa.serial;
105 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
106 ans[ai].rdata.soa_record.retry = rec->data.soa.retry;
107 ans[ai].rdata.soa_record.expire = rec->data.soa.expire;
108 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
109 break;
110 case DNS_QTYPE_PTR:
111 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
112 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ptr_record);
113 break;
114 case DNS_QTYPE_MX:
115 ans[ai].rdata.mx_record.preference = rec->data.mx.wPriority;
116 ans[ai].rdata.mx_record.exchange = talloc_strdup(
117 ans, rec->data.mx.nameTarget);
118 if (ans[ai].rdata.mx_record.exchange == NULL) {
119 return WERR_NOT_ENOUGH_MEMORY;
120 }
121 break;
122 case DNS_QTYPE_TXT:
123 ndr_err = ndr_dnsp_string_list_copy(ans,
124 &rec->data.txt,
125 &ans[ai].rdata.txt_record.txt);
126 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
127 return WERR_NOT_ENOUGH_MEMORY;
128 }
129 break;
130 default:
131 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
132 return DNS_ERR(NOT_IMPLEMENTED);
133 }
134
135 ans[ai].name = talloc_strdup(ans, name);
136 W_ERROR_HAVE_NO_MEMORY(ans[ai].name);
137 ans[ai].rr_type = (enum dns_qtype)rec->wType;
138 ans[ai].rr_class = DNS_QCLASS_IN;
139 ans[ai].ttl = rec->dwTtlSeconds;
140 ans[ai].length = UINT16_MAX;
141
142 *answers = ans;
143
144 return WERR_OK;
145 }
146
147 static WERROR add_dns_res_rec(struct dns_res_rec **pdst,
148 const struct dns_res_rec *src)
149 {
150 struct dns_res_rec *dst = *pdst;
151 uint16_t di = talloc_array_length(dst);
152 enum ndr_err_code ndr_err;
153
154 if (di == UINT16_MAX) {
155 return WERR_BUFFER_OVERFLOW;
156 }
157
158 dst = talloc_realloc(dst, dst, struct dns_res_rec, di+1);
159 if (dst == NULL) {
160 return WERR_NOT_ENOUGH_MEMORY;
161 }
162
163 ZERO_STRUCT(dst[di]);
164
165 dst[di] = (struct dns_res_rec) {
166 .name = talloc_strdup(dst, src->name),
167 .rr_type = src->rr_type,
168 .rr_class = src->rr_class,
169 .ttl = src->ttl,
170 .length = src->length
171 };
172
173 if (dst[di].name == NULL) {
174 return WERR_NOT_ENOUGH_MEMORY;
175 }
176
177 switch (src->rr_type) {
178 case DNS_QTYPE_CNAME:
179 dst[di].rdata.cname_record = talloc_strdup(
180 dst, src->rdata.cname_record);
181 if (dst[di].rdata.cname_record == NULL) {
182 return WERR_NOT_ENOUGH_MEMORY;
183 }
184 break;
185 case DNS_QTYPE_A:
186 dst[di].rdata.ipv4_record = talloc_strdup(
187 dst, src->rdata.ipv4_record);
188 if (dst[di].rdata.ipv4_record == NULL) {
189 return WERR_NOT_ENOUGH_MEMORY;
190 }
191 break;
192 case DNS_QTYPE_AAAA:
193 dst[di].rdata.ipv6_record = talloc_strdup(
194 dst, src->rdata.ipv6_record);
195 if (dst[di].rdata.ipv6_record == NULL) {
196 return WERR_NOT_ENOUGH_MEMORY;
197 }
198 break;
199 case DNS_TYPE_NS:
200 dst[di].rdata.ns_record = talloc_strdup(
201 dst, src->rdata.ns_record);
202 if (dst[di].rdata.ns_record == NULL) {
203 return WERR_NOT_ENOUGH_MEMORY;
204 }
205 break;
206 case DNS_QTYPE_SRV:
207 dst[di].rdata.srv_record = (struct dns_srv_record) {
208 .priority = src->rdata.srv_record.priority,
209 .weight = src->rdata.srv_record.weight,
210 .port = src->rdata.srv_record.port,
211 .target = talloc_strdup(
212 dst, src->rdata.srv_record.target)
213 };
214 if (dst[di].rdata.srv_record.target == NULL) {
215 return WERR_NOT_ENOUGH_MEMORY;
216 }
217 break;
218 case DNS_QTYPE_SOA:
219 dst[di].rdata.soa_record = (struct dns_soa_record) {
220 .mname = talloc_strdup(
221 dst, src->rdata.soa_record.mname),
222 .rname = talloc_strdup(
223 dst, src->rdata.soa_record.rname),
224 .serial = src->rdata.soa_record.serial,
225 .refresh = src->rdata.soa_record.refresh,
226 .retry = src->rdata.soa_record.retry,
227 .expire = src->rdata.soa_record.expire,
228 .minimum = src->rdata.soa_record.minimum
229 };
230
231 if ((dst[di].rdata.soa_record.mname == NULL) ||
232 (dst[di].rdata.soa_record.rname == NULL)) {
233 return WERR_NOT_ENOUGH_MEMORY;
234 }
235
236 break;
237 case DNS_QTYPE_PTR:
238 dst[di].rdata.ptr_record = talloc_strdup(
239 dst, src->rdata.ptr_record);
240 if (dst[di].rdata.ptr_record == NULL) {
241 return WERR_NOT_ENOUGH_MEMORY;
242 }
243 break;
244 case DNS_QTYPE_MX:
245 dst[di].rdata.mx_record = (struct dns_mx_record) {
246 .preference = src->rdata.mx_record.preference,
247 .exchange = talloc_strdup(
248 src, src->rdata.mx_record.exchange)
249 };
250
251 if (dst[di].rdata.mx_record.exchange == NULL) {
252 return WERR_NOT_ENOUGH_MEMORY;
253 }
254 break;
255 case DNS_QTYPE_TXT:
256 ndr_err = ndr_dnsp_string_list_copy(dst,
257 &src->rdata.txt_record.txt,
258 &dst[di].rdata.txt_record.txt);
259 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
260 return WERR_NOT_ENOUGH_MEMORY;
261 }
262 break;
263 default:
264 DBG_WARNING("Got unhandled type %u query.\n", src->rr_type);
265 return DNS_ERR(NOT_IMPLEMENTED);
266 }
267
268 *pdst = dst;
269
270 return WERR_OK;
271 }
272
273 struct ask_forwarder_state {
274 struct dns_name_packet *reply;
275 };
276
277 static void ask_forwarder_done(struct tevent_req *subreq);
278
279 static struct tevent_req *ask_forwarder_send(
280 TALLOC_CTX *mem_ctx, struct tevent_context *ev,
281 const char *forwarder, struct dns_name_question *question)
282 {
283 struct tevent_req *req, *subreq;
284 struct ask_forwarder_state *state;
285
286 req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state);
287 if (req == NULL) {
288 return NULL;
289 }
290
291 subreq = dns_cli_request_send(state, ev, forwarder,
292 question->name, question->question_class,
293 question->question_type);
294 if (tevent_req_nomem(subreq, req)) {
295 return tevent_req_post(req, ev);
296 }
297 tevent_req_set_callback(subreq, ask_forwarder_done, req);
298 return req;
299 }
300
301 static void ask_forwarder_done(struct tevent_req *subreq)
302 {
303 struct tevent_req *req = tevent_req_callback_data(
304 subreq, struct tevent_req);
305 struct ask_forwarder_state *state = tevent_req_data(
306 req, struct ask_forwarder_state);
307 int ret;
308
309 ret = dns_cli_request_recv(subreq, state, &state->reply);
310 TALLOC_FREE(subreq);
311
312 if (ret != 0) {
313 tevent_req_werror(req, unix_to_werror(ret));
314 return;
315 }
316
317 tevent_req_done(req);
318 }
319
320 static WERROR ask_forwarder_recv(
321 struct tevent_req *req, TALLOC_CTX *mem_ctx,
322 struct dns_res_rec **answers, uint16_t *ancount,
323 struct dns_res_rec **nsrecs, uint16_t *nscount,
324 struct dns_res_rec **additional, uint16_t *arcount)
325 {
326 struct ask_forwarder_state *state = tevent_req_data(
327 req, struct ask_forwarder_state);
328 struct dns_name_packet *in_packet = state->reply;
329 WERROR err;
330
331 if (tevent_req_is_werror(req, &err)) {
332 return err;
333 }
334
335 *ancount = in_packet->ancount;
336 *answers = talloc_move(mem_ctx, &in_packet->answers);
337
338 *nscount = in_packet->nscount;
339 *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
340
341 *arcount = in_packet->arcount;
342 *additional = talloc_move(mem_ctx, &in_packet->additional);
343
344 return WERR_OK;
345 }
346
347 static WERROR add_zone_authority_record(struct dns_server *dns,
348 TALLOC_CTX *mem_ctx,
349 const struct dns_name_question *question,
350 struct dns_res_rec **nsrecs)
351 {
352 const char *zone = NULL;
353 struct dnsp_DnssrvRpcRecord *recs;
354 struct dns_res_rec *ns = *nsrecs;
355 uint16_t rec_count;
356 struct ldb_dn *dn = NULL;
357 unsigned int ri;
358 WERROR werror;
359
360 zone = dns_get_authoritative_zone(dns, question->name);
361 DEBUG(10, ("Creating zone authority record for '%s'\n", zone));
362
363 werror = dns_name2dn(dns, mem_ctx, zone, &dn);
364 if (!W_ERROR_IS_OK(werror)) {
365 return werror;
366 }
367
368 werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
369 if (!W_ERROR_IS_OK(werror)) {
370 return werror;
371 }
372
373 for (ri = 0; ri < rec_count; ri++) {
374 if (recs[ri].wType == DNS_TYPE_SOA) {
375 werror = add_response_rr(zone, &recs[ri], &ns);
376 if (!W_ERROR_IS_OK(werror)) {
377 return werror;
378 }
379 }
380 }
381
382 *nsrecs = ns;
383
384 return WERR_OK;
385 }
386
387 static struct tevent_req *handle_authoritative_send(
388 TALLOC_CTX *mem_ctx, struct tevent_context *ev,
389 struct dns_server *dns, const char *forwarder,
390 struct dns_name_question *question,
391 struct dns_res_rec **answers, struct dns_res_rec **nsrecs,
392 size_t cname_depth);
393 static WERROR handle_authoritative_recv(struct tevent_req *req);
394
395 struct handle_dnsrpcrec_state {
396 struct dns_res_rec **answers;
397 struct dns_res_rec **nsrecs;
398 };
399
400 static void handle_dnsrpcrec_gotauth(struct tevent_req *subreq);
401 static void handle_dnsrpcrec_gotforwarded(struct tevent_req *subreq);
402
403 static struct tevent_req *handle_dnsrpcrec_send(
404 TALLOC_CTX *mem_ctx, struct tevent_context *ev,
405 struct dns_server *dns, const char *forwarder,
406 const struct dns_name_question *question,
407 struct dnsp_DnssrvRpcRecord *rec,
408 struct dns_res_rec **answers, struct dns_res_rec **nsrecs,
409 size_t cname_depth)
410 {
411 struct tevent_req *req, *subreq;
412 struct handle_dnsrpcrec_state *state;
413 struct dns_name_question *new_q;
414 bool resolve_cname;
415 WERROR werr;
416
417 req = tevent_req_create(mem_ctx, &state,
418 struct handle_dnsrpcrec_state);
419 if (req == NULL) {
420 return NULL;
421 }
422 state->answers = answers;
423 state->nsrecs = nsrecs;
424
425 if (cname_depth >= MAX_Q_RECURSION_DEPTH) {
426 tevent_req_done(req);
427 return tevent_req_post(req, ev);
428 }
429
430 resolve_cname = ((rec->wType == DNS_TYPE_CNAME) &&
431 ((question->question_type == DNS_QTYPE_A) ||
432 (question->question_type == DNS_QTYPE_AAAA)));
433
434 if (!resolve_cname) {
435 if ((question->question_type != DNS_QTYPE_ALL) &&
436 (rec->wType !=
437 (enum dns_record_type) question->question_type)) {
438 tevent_req_done(req);
439 return tevent_req_post(req, ev);
440 }
441
442 werr = add_response_rr(question->name, rec, state->answers);
443 if (tevent_req_werror(req, werr)) {
444 return tevent_req_post(req, ev);
445 }
446
447 tevent_req_done(req);
448 return tevent_req_post(req, ev);
449 }
450
451 werr = add_response_rr(question->name, rec, state->answers);
452 if (tevent_req_werror(req, werr)) {
453 return tevent_req_post(req, ev);
454 }
455
456 new_q = talloc(state, struct dns_name_question);
457 if (tevent_req_nomem(new_q, req)) {
458 return tevent_req_post(req, ev);
459 }
460
461 *new_q = (struct dns_name_question) {
462 .question_type = question->question_type,
463 .question_class = question->question_class,
464 .name = rec->data.cname
465 };
466
467 if (dns_authoritative_for_zone(dns, new_q->name)) {
468 subreq = handle_authoritative_send(
469 state, ev, dns, forwarder, new_q,
470 state->answers, state->nsrecs,
471 cname_depth + 1);
472 if (tevent_req_nomem(subreq, req)) {
473 return tevent_req_post(req, ev);
474 }
475 tevent_req_set_callback(subreq, handle_dnsrpcrec_gotauth, req);
476 return req;
477 }
478
479 subreq = ask_forwarder_send(state, ev, forwarder, new_q);
480 if (tevent_req_nomem(subreq, req)) {
481 return tevent_req_post(req, ev);
482 }
483 tevent_req_set_callback(subreq, handle_dnsrpcrec_gotforwarded, req);
484
485 return req;
486 }
487
488 static void handle_dnsrpcrec_gotauth(struct tevent_req *subreq)
489 {
490 struct tevent_req *req = tevent_req_callback_data(
491 subreq, struct tevent_req);
492 WERROR werr;
493
494 werr = handle_authoritative_recv(subreq);
495 TALLOC_FREE(subreq);
496 if (tevent_req_werror(req, werr)) {
497 return;
498 }
499 tevent_req_done(req);
500 }
501
502 static void handle_dnsrpcrec_gotforwarded(struct tevent_req *subreq)
503 {
504 struct tevent_req *req = tevent_req_callback_data(
505 subreq, struct tevent_req);
506 struct handle_dnsrpcrec_state *state = tevent_req_data(
507 req, struct handle_dnsrpcrec_state);
508 struct dns_res_rec *answers, *nsrecs, *additional;
509 uint16_t ancount = 0;
510 uint16_t nscount = 0;
511 uint16_t arcount = 0;
512 uint16_t i;
513 WERROR werr;
514
515 werr = ask_forwarder_recv(subreq, state, &answers, &ancount,
516 &nsrecs, &nscount, &additional, &arcount);
517 if (tevent_req_werror(req, werr)) {
518 return;
519 }
520
521 for (i=0; i<ancount; i++) {
522 werr = add_dns_res_rec(state->answers, &answers[i]);
523 if (tevent_req_werror(req, werr)) {
524 return;
525 }
526 }
527
528 for (i=0; i<nscount; i++) {
529 werr = add_dns_res_rec(state->nsrecs, &nsrecs[i]);
530 if (tevent_req_werror(req, werr)) {
531 return;
532 }
533 }
534
535 tevent_req_done(req);
536 }
537
538 static WERROR handle_dnsrpcrec_recv(struct tevent_req *req)
539 {
540 return tevent_req_simple_recv_werror(req);
541 }
542
543 struct handle_authoritative_state {
544 struct tevent_context *ev;
545 struct dns_server *dns;
546 struct dns_name_question *question;
547 const char *forwarder;
548
549 struct dnsp_DnssrvRpcRecord *recs;
550 uint16_t rec_count;
551 uint16_t recs_done;
552
553 struct dns_res_rec **answers;
554 struct dns_res_rec **nsrecs;
555
556 size_t cname_depth;
557 };
558
559 static void handle_authoritative_done(struct tevent_req *subreq);
560
561 static struct tevent_req *handle_authoritative_send(
562 TALLOC_CTX *mem_ctx, struct tevent_context *ev,
563 struct dns_server *dns, const char *forwarder,
564 struct dns_name_question *question,
565 struct dns_res_rec **answers, struct dns_res_rec **nsrecs,
566 size_t cname_depth)
567 {
568 struct tevent_req *req, *subreq;
569 struct handle_authoritative_state *state;
570 struct ldb_dn *dn = NULL;
571 WERROR werr;
572
573 req = tevent_req_create(mem_ctx, &state,
574 struct handle_authoritative_state);
575 if (req == NULL) {
576 return NULL;
577 }
578 state->ev = ev;
579 state->dns = dns;
580 state->question = question;
581 state->forwarder = forwarder;
582 state->answers = answers;
583 state->nsrecs = nsrecs;
584 state->cname_depth = cname_depth;
585
586 werr = dns_name2dn(dns, state, question->name, &dn);
587 if (tevent_req_werror(req, werr)) {
588 return tevent_req_post(req, ev);
589 }
590 werr = dns_lookup_records_wildcard(dns, state, dn, &state->recs,
591 &state->rec_count);
592 TALLOC_FREE(dn);
593 if (tevent_req_werror(req, werr)) {
594 return tevent_req_post(req, ev);
595 }
596
597 if (state->rec_count == 0) {
598 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
599 return tevent_req_post(req, ev);
600 }
601
602 subreq = handle_dnsrpcrec_send(
603 state, state->ev, state->dns, state->forwarder,
604 state->question, &state->recs[state->recs_done],
605 state->answers, state->nsrecs,
606 state->cname_depth);
607 if (tevent_req_nomem(subreq, req)) {
608 return tevent_req_post(req, ev);
609 }
610 tevent_req_set_callback(subreq, handle_authoritative_done, req);
611 return req;
612 }
613
614 static void handle_authoritative_done(struct tevent_req *subreq)
615 {
616 struct tevent_req *req = tevent_req_callback_data(
617 subreq, struct tevent_req);
618 struct handle_authoritative_state *state = tevent_req_data(
619 req, struct handle_authoritative_state);
620 WERROR werr;
621
622 werr = handle_dnsrpcrec_recv(subreq);
623 TALLOC_FREE(subreq);
624 if (tevent_req_werror(req, werr)) {
625 return;
626 }
627
628 state->recs_done += 1;
629
630 if (state->recs_done == state->rec_count) {
631 tevent_req_done(req);
632 return;
633 }
634
635 subreq = handle_dnsrpcrec_send(
636 state, state->ev, state->dns, state->forwarder,
637 state->question, &state->recs[state->recs_done],
638 state->answers, state->nsrecs,
639 state->cname_depth);
640 if (tevent_req_nomem(subreq, req)) {
641 return;
642 }
643 tevent_req_set_callback(subreq, handle_authoritative_done, req);
644 }
645
646 static WERROR handle_authoritative_recv(struct tevent_req *req)
647 {
648 struct handle_authoritative_state *state = tevent_req_data(
649 req, struct handle_authoritative_state);
650 WERROR werr;
651
652 if (tevent_req_is_werror(req, &werr)) {
653 return werr;
654 }
655
656 werr = add_zone_authority_record(state->dns, state, state->question,
657 state->nsrecs);
658 if (!W_ERROR_IS_OK(werr)) {
659 return werr;
660 }
661
662 return WERR_OK;
663 }
664
665 static NTSTATUS create_tkey(struct dns_server *dns,
666 const char* name,
667 const char* algorithm,
668 const struct tsocket_address *remote_address,
669 const struct tsocket_address *local_address,
670 struct dns_server_tkey **tkey)
671 {
672 NTSTATUS status;
673 struct dns_server_tkey_store *store = dns->tkeys;
674 struct dns_server_tkey *k = talloc_zero(store, struct dns_server_tkey);
675
676 if (k == NULL) {
677 return NT_STATUS_NO_MEMORY;
678 }
679
680 k->name = talloc_strdup(k, name);
681
682 if (k->name == NULL) {
683 return NT_STATUS_NO_MEMORY;
684 }
685
686 k->algorithm = talloc_strdup(k, algorithm);
687 if (k->algorithm == NULL) {
688 return NT_STATUS_NO_MEMORY;
689 }
690
691 /*
692 * We only allow SPNEGO/KRB5 currently
693 * and rely on the backend to be RPC/IPC free.
694 *
695 * It allows gensec_update() not to block.
696 */
697 status = samba_server_gensec_krb5_start(k,
698 dns->task->event_ctx,
699 dns->task->msg_ctx,
700 dns->task->lp_ctx,
701 dns->server_credentials,
702 "dns",
703 &k->gensec);
704 if (!NT_STATUS_IS_OK(status)) {
705 DEBUG(1, ("Failed to start GENSEC server code: %s\n", nt_errstr(status)));
706 *tkey = NULL;
707 return status;
708 }
709
710 gensec_want_feature(k->gensec, GENSEC_FEATURE_SIGN);
711
712 status = gensec_set_remote_address(k->gensec,
713 remote_address);
714 if (!NT_STATUS_IS_OK(status)) {
715 DEBUG(1, ("Failed to set remote address into GENSEC: %s\n",
716 nt_errstr(status)));
717 *tkey = NULL;
718 return status;
719 }
720
721 status = gensec_set_local_address(k->gensec,
722 local_address);
723 if (!NT_STATUS_IS_OK(status)) {
724 DEBUG(1, ("Failed to set local address into GENSEC: %s\n",
725 nt_errstr(status)));
726 *tkey = NULL;
727 return status;
728 }
729
730 status = gensec_start_mech_by_oid(k->gensec, GENSEC_OID_SPNEGO);
731
732 if (!NT_STATUS_IS_OK(status)) {
733 DEBUG(1, ("Failed to start GENSEC server code: %s\n",
734 nt_errstr(status)));
735 *tkey = NULL;
736 return status;
737 }
738
739 TALLOC_FREE(store->tkeys[store->next_idx]);
740
741 store->tkeys[store->next_idx] = k;
742 (store->next_idx)++;
743 store->next_idx %= store->size;
744
745 *tkey = k;
746 return NT_STATUS_OK;
747 }
748
749 static NTSTATUS accept_gss_ticket(TALLOC_CTX *mem_ctx,
750 struct dns_server *dns,
751 struct dns_server_tkey *tkey,
752 const DATA_BLOB *key,
753 DATA_BLOB *reply,
754 uint16_t *dns_auth_error)
755 {
756 NTSTATUS status;
757
758 /*
759 * We use samba_server_gensec_krb5_start(),
760 * which only allows SPNEGO/KRB5 currently
761 * and makes sure the backend to be RPC/IPC free.
762 *
763 * See gensec_gssapi_update_internal() as
764 * GENSEC_SERVER.
765 *
766 * It allows gensec_update() not to block.
767 *
768 * If that changes in future we need to use
769 * gensec_update_send/recv here!
770 */
771 status = gensec_update(tkey->gensec, mem_ctx,
772 *key, reply);
773
774 if (NT_STATUS_EQUAL(NT_STATUS_MORE_PROCESSING_REQUIRED, status)) {
775 *dns_auth_error = DNS_RCODE_OK;
776 return status;
777 }
778
779 if (NT_STATUS_IS_OK(status)) {
780
781 status = gensec_session_info(tkey->gensec, tkey, &tkey->session_info);
782 if (!NT_STATUS_IS_OK(status)) {
783 *dns_auth_error = DNS_RCODE_BADKEY;
784 return status;
785 }
786 *dns_auth_error = DNS_RCODE_OK;
787 }
788
789 return status;
790 }
791
792 static WERROR handle_tkey(struct dns_server *dns,
793 TALLOC_CTX *mem_ctx,
794 const struct dns_name_packet *in,
795 struct dns_request_state *state,
796 struct dns_res_rec **answers,
797 uint16_t *ancount)
798 {
799 struct dns_res_rec *in_tkey = NULL;
800 struct dns_res_rec *ret_tkey;
801 uint16_t i;
802
803 for (i = 0; i < in->arcount; i++) {
804 if (in->additional[i].rr_type == DNS_QTYPE_TKEY) {
805 in_tkey = &in->additional[i];
806 break;
807 }
808 }
809
810 /* If this is a TKEY query, it should have a TKEY RR.
811 * Behaviour is not really specified in RFC 2930 or RFC 3645, but
812 * FORMAT_ERROR seems to be what BIND uses .*/
813 if (in_tkey == NULL) {
814 return DNS_ERR(FORMAT_ERROR);
815 }
816
817 ret_tkey = talloc_zero(mem_ctx, struct dns_res_rec);
818 if (ret_tkey == NULL) {
819 return WERR_NOT_ENOUGH_MEMORY;
820 }
821
822 ret_tkey->name = talloc_strdup(ret_tkey, in_tkey->name);
823 if (ret_tkey->name == NULL) {
824 return WERR_NOT_ENOUGH_MEMORY;
825 }
826
827 ret_tkey->rr_type = DNS_QTYPE_TKEY;
828 ret_tkey->rr_class = DNS_QCLASS_ANY;
829 ret_tkey->length = UINT16_MAX;
830
831 ret_tkey->rdata.tkey_record.algorithm = talloc_strdup(ret_tkey,
832 in_tkey->rdata.tkey_record.algorithm);
833 if (ret_tkey->rdata.tkey_record.algorithm == NULL) {
834 return WERR_NOT_ENOUGH_MEMORY;
835 }
836
837 ret_tkey->rdata.tkey_record.inception = in_tkey->rdata.tkey_record.inception;
838 ret_tkey->rdata.tkey_record.expiration = in_tkey->rdata.tkey_record.expiration;
839 ret_tkey->rdata.tkey_record.mode = in_tkey->rdata.tkey_record.mode;
840
841 switch (in_tkey->rdata.tkey_record.mode) {
842 case DNS_TKEY_MODE_DH:
843 /* FIXME: According to RFC 2930, we MUST support this, but we don't.
844 * Still, claim it's a bad key instead of a bad mode */
845 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
846 break;
847 case DNS_TKEY_MODE_GSSAPI: {
848 NTSTATUS status;
849 struct dns_server_tkey *tkey;
850 DATA_BLOB key;
851 DATA_BLOB reply;
852
853 tkey = dns_find_tkey(dns->tkeys, in->questions[0].name);
854 if (tkey != NULL && tkey->complete) {
855 /* TODO: check if the key is still valid */
856 DEBUG(1, ("Rejecting tkey negotiation for already established key\n"));
857 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADNAME;
858 break;
859 }
860
861 if (tkey == NULL) {
862 status = create_tkey(dns, in->questions[0].name,
863 in_tkey->rdata.tkey_record.algorithm,
864 state->remote_address,
865 state->local_address,
866 &tkey);
867 if (!NT_STATUS_IS_OK(status)) {
868 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
869 return ntstatus_to_werror(status);
870 }
871 }
872
873 key.data = in_tkey->rdata.tkey_record.key_data;
874 key.length = in_tkey->rdata.tkey_record.key_size;
875
876 status = accept_gss_ticket(ret_tkey, dns, tkey, &key, &reply,
877 &ret_tkey->rdata.tkey_record.error);
878 if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
879 DEBUG(1, ("More processing required\n"));
880 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
881 } else if (NT_STATUS_IS_OK(status)) {
882 DBG_DEBUG("Tkey handshake completed\n");
883 ret_tkey->rdata.tkey_record.key_size = reply.length;
884 ret_tkey->rdata.tkey_record.key_data = talloc_memdup(ret_tkey,
885 reply.data,
886 reply.length);
887 if (ret_tkey->rdata.tkey_record.key_data == NULL) {
888 return WERR_NOT_ENOUGH_MEMORY;
889 }
890 state->sign = true;
891 state->key_name = talloc_strdup(state->mem_ctx, tkey->name);
892 if (state->key_name == NULL) {
893 return WERR_NOT_ENOUGH_MEMORY;
894 }
895 } else {
896 DEBUG(1, ("GSS key negotiation returned %s\n", nt_errstr(status)));
897 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
898 }
899
900 break;
901 }
902 case DNS_TKEY_MODE_DELETE:
903 /* TODO: implement me */
904 DEBUG(1, ("Should delete tkey here\n"));
905 ret_tkey->rdata.tkey_record.error = DNS_RCODE_OK;
906 break;
907 case DNS_TKEY_MODE_NULL:
908 case DNS_TKEY_MODE_SERVER:
909 case DNS_TKEY_MODE_CLIENT:
910 case DNS_TKEY_MODE_LAST:
911 /* We don't have to implement these, return a mode error */
912 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADMODE;
913 break;
914 default:
915 DEBUG(1, ("Unsupported TKEY mode %d\n",
916 in_tkey->rdata.tkey_record.mode));
917 }
918
919 *answers = ret_tkey;
920 *ancount = 1;
921
922 return WERR_OK;
923 }
924
925 struct dns_server_process_query_state {
926 struct tevent_context *ev;
927 struct dns_server *dns;
928 struct dns_name_question *question;
929
930 struct dns_res_rec *answers;
931 uint16_t ancount;
932 struct dns_res_rec *nsrecs;
933 uint16_t nscount;
934 struct dns_res_rec *additional;
935 uint16_t arcount;
936 struct forwarder_string *forwarders;
937 };
938
939 static void dns_server_process_query_got_auth(struct tevent_req *subreq);
940 static void dns_server_process_query_got_response(struct tevent_req *subreq);
941
942 struct tevent_req *dns_server_process_query_send(
943 TALLOC_CTX *mem_ctx, struct tevent_context *ev,
944 struct dns_server *dns, struct dns_request_state *req_state,
945 const struct dns_name_packet *in)
946 {
947 struct tevent_req *req, *subreq;
948 struct dns_server_process_query_state *state;
949 const char **forwarders = NULL;
950 unsigned int i;
951
952 req = tevent_req_create(mem_ctx, &state,
953 struct dns_server_process_query_state);
954 if (req == NULL) {
955 return NULL;
956 }
957 if (in->qdcount != 1) {
958 tevent_req_werror(req, DNS_ERR(FORMAT_ERROR));
959 return tevent_req_post(req, ev);
960 }
961
962 /* Windows returns NOT_IMPLEMENTED on this as well */
963 if (in->questions[0].question_class == DNS_QCLASS_NONE) {
964 tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED));
965 return tevent_req_post(req, ev);
966 }
967
968 if (in->questions[0].question_type == DNS_QTYPE_TKEY) {
969 WERROR err;
970
971 err = handle_tkey(dns, state, in, req_state,
972 &state->answers, &state->ancount);
973 if (tevent_req_werror(req, err)) {
974 return tevent_req_post(req, ev);
975 }
976 tevent_req_done(req);
977 return tevent_req_post(req, ev);
978 }
979
980 state->dns = dns;
981 state->ev = ev;
982 state->question = &in->questions[0];
983
984 forwarders = lpcfg_dns_forwarder(dns->task->lp_ctx);
985 for (i = 0; forwarders != NULL && forwarders[i] != NULL; i++) {
986 struct forwarder_string *f = talloc_zero(state,
987 struct forwarder_string);
988 f->forwarder = forwarders[i];
989 DLIST_ADD_END(state->forwarders, f);
990 }
991
992 if (dns_authoritative_for_zone(dns, in->questions[0].name)) {
993
994 req_state->flags |= DNS_FLAG_AUTHORITATIVE;
995
996 /*
997 * Initialize the response arrays, so that we can use
998 * them as their own talloc contexts when doing the
999 * realloc
1000 */
1001 state->answers = talloc_array(state, struct dns_res_rec, 0);
1002 if (tevent_req_nomem(state->answers, req)) {
1003 return tevent_req_post(req, ev);
1004 }
1005 state->nsrecs = talloc_array(state, struct dns_res_rec, 0);
1006 if (tevent_req_nomem(state->nsrecs, req)) {
1007 return tevent_req_post(req, ev);
1008 }
1009
1010 subreq = handle_authoritative_send(
1011 state, ev, dns, (forwarders == NULL ? NULL : forwarders[0]),
1012 &in->questions[0], &state->answers, &state->nsrecs,
1013 0); /* cname_depth */
1014 if (tevent_req_nomem(subreq, req)) {
1015 return tevent_req_post(req, ev);
1016 }
1017 tevent_req_set_callback(
1018 subreq, dns_server_process_query_got_auth, req);
1019 return req;
1020 }
1021
1022 if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) &&
1023 (req_state->flags & DNS_FLAG_RECURSION_AVAIL)) {
1024 DEBUG(5, ("Not authoritative for '%s', forwarding\n",
1025 in->questions[0].name));
1026
1027 subreq = ask_forwarder_send(state, ev,
1028 (forwarders == NULL ? NULL : forwarders[0]),
1029 &in->questions[0]);
1030 if (tevent_req_nomem(subreq, req)) {
1031 return tevent_req_post(req, ev);
1032 }
1033 tevent_req_set_callback(
1034 subreq, dns_server_process_query_got_response, req);
1035 return req;
1036 }
1037
1038 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
1039 return tevent_req_post(req, ev);
1040 }
1041
1042 static void dns_server_process_query_got_response(struct tevent_req *subreq)
1043 {
1044 struct tevent_req *req = tevent_req_callback_data(
1045 subreq, struct tevent_req);
1046 struct dns_server_process_query_state *state = tevent_req_data(
1047 req, struct dns_server_process_query_state);
1048 WERROR werr;
1049
1050 werr = ask_forwarder_recv(subreq, state,
1051 &state->answers, &state->ancount,
1052 &state->nsrecs, &state->nscount,
1053 &state->additional, &state->arcount);
1054 TALLOC_FREE(subreq);
1055
1056 /* If you get an error, attempt a different forwarder */
1057 if (!W_ERROR_IS_OK(werr)) {
1058 if (state->forwarders != NULL) {
1059 DLIST_REMOVE(state->forwarders, state->forwarders);
1060 }
1061
1062 /* If you have run out of forwarders, simply finish */
1063 if (state->forwarders == NULL) {
1064 tevent_req_werror(req, werr);
1065 return;
1066 }
1067
1068 DEBUG(5, ("DNS query returned %s, trying another forwarder.\n",
1069 win_errstr(werr)));
1070 subreq = ask_forwarder_send(state, state->ev,
1071 state->forwarders->forwarder,
1072 state->question);
1073
1074 if (tevent_req_nomem(subreq, req)) {
1075 return;
1076 }
1077
1078 tevent_req_set_callback(subreq,
1079 dns_server_process_query_got_response,
1080 req);
1081 return;
1082 }
1083
1084 tevent_req_done(req);
1085 }
1086
1087 static void dns_server_process_query_got_auth(struct tevent_req *subreq)
1088 {
1089 struct tevent_req *req = tevent_req_callback_data(
1090 subreq, struct tevent_req);
1091 struct dns_server_process_query_state *state = tevent_req_data(
1092 req, struct dns_server_process_query_state);
1093 WERROR werr;
1094
1095 werr = handle_authoritative_recv(subreq);
1096 TALLOC_FREE(subreq);
1097
1098 /* If you get an error, attempt a different forwarder */
1099 if (!W_ERROR_IS_OK(werr)) {
1100 if (state->forwarders != NULL) {
1101 DLIST_REMOVE(state->forwarders, state->forwarders);
1102 }
1103
1104 /* If you have run out of forwarders, simply finish */
1105 if (state->forwarders == NULL) {
1106 tevent_req_werror(req, werr);
1107 return;
1108 }
1109
1110 DEBUG(5, ("Error: %s, trying a different forwarder.\n",
1111 win_errstr(werr)));
1112 subreq = handle_authoritative_send(state, state->ev, state->dns,
1113 state->forwarders->forwarder,
1114 state->question, &state->answers,
1115 &state->nsrecs,
1116 0); /* cname_depth */
1117
1118 if (tevent_req_nomem(subreq, req)) {
1119 return;
1120 }
1121
1122 tevent_req_set_callback(subreq,
1123 dns_server_process_query_got_auth,
1124 req);
1125 return;
1126 }
1127
1128 state->ancount = talloc_array_length(state->answers);
1129 state->nscount = talloc_array_length(state->nsrecs);
1130 state->arcount = talloc_array_length(state->additional);
1131
1132 tevent_req_done(req);
1133 }
1134
1135 WERROR dns_server_process_query_recv(
1136 struct tevent_req *req, TALLOC_CTX *mem_ctx,
1137 struct dns_res_rec **answers, uint16_t *ancount,
1138 struct dns_res_rec **nsrecs, uint16_t *nscount,
1139 struct dns_res_rec **additional, uint16_t *arcount)
1140 {
1141 struct dns_server_process_query_state *state = tevent_req_data(
1142 req, struct dns_server_process_query_state);
1143 WERROR err = WERR_OK;
1144
1145 if (tevent_req_is_werror(req, &err)) {
1146
1147 if ((!W_ERROR_EQUAL(err, DNS_ERR(NAME_ERROR))) &&
1148 (!W_ERROR_EQUAL(err, WERR_DNS_ERROR_NAME_DOES_NOT_EXIST))) {
1149 return err;
1150 }
1151 }
1152 *answers = talloc_move(mem_ctx, &state->answers);
1153 *ancount = state->ancount;
1154 *nsrecs = talloc_move(mem_ctx, &state->nsrecs);
1155 *nscount = state->nscount;
1156 *additional = talloc_move(mem_ctx, &state->additional);
1157 *arcount = state->arcount;
1158 return err;
1159 }
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