xref: /freebsd/contrib/ldns/dane.c (revision ca987d4641cdcd7f27e153db17c5bf064934faf5)
1 /*
2  * Verify or create TLS authentication with DANE (RFC6698)
3  *
4  * (c) NLnetLabs 2012
5  *
6  * See the file LICENSE for the license.
7  *
8  */
9 
10 #include <ldns/config.h>
11 #ifdef USE_DANE
12 
13 #include <ldns/ldns.h>
14 #include <ldns/dane.h>
15 
16 #include <unistd.h>
17 #include <stdlib.h>
18 #include <sys/types.h>
19 #ifdef HAVE_SYS_SOCKET_H
20 #include <sys/socket.h>
21 #endif
22 #ifdef HAVE_NETDB_H
23 #include <netdb.h>
24 #endif
25 
26 #ifdef HAVE_SSL
27 #include <openssl/ssl.h>
28 #include <openssl/err.h>
29 #include <openssl/x509v3.h>
30 #endif
31 
32 ldns_status
33 ldns_dane_create_tlsa_owner(ldns_rdf** tlsa_owner, const ldns_rdf* name,
34 		uint16_t port, ldns_dane_transport transport)
35 {
36 	char buf[LDNS_MAX_DOMAINLEN];
37 	size_t s;
38 
39 	assert(tlsa_owner != NULL);
40 	assert(name != NULL);
41 	assert(ldns_rdf_get_type(name) == LDNS_RDF_TYPE_DNAME);
42 
43 	s = (size_t)snprintf(buf, LDNS_MAX_DOMAINLEN, "X_%d", (int)port);
44 	buf[0] = (char)(s - 1);
45 
46 	switch(transport) {
47 	case LDNS_DANE_TRANSPORT_TCP:
48 		s += snprintf(buf + s, LDNS_MAX_DOMAINLEN - s, "\004_tcp");
49 		break;
50 
51 	case LDNS_DANE_TRANSPORT_UDP:
52 		s += snprintf(buf + s, LDNS_MAX_DOMAINLEN - s, "\004_udp");
53 		break;
54 
55 	case LDNS_DANE_TRANSPORT_SCTP:
56 		s += snprintf(buf + s, LDNS_MAX_DOMAINLEN - s, "\005_sctp");
57 		break;
58 
59 	default:
60 		return LDNS_STATUS_DANE_UNKNOWN_TRANSPORT;
61 	}
62 	if (s + ldns_rdf_size(name) > LDNS_MAX_DOMAINLEN) {
63 		return LDNS_STATUS_DOMAINNAME_OVERFLOW;
64 	}
65 	memcpy(buf + s, ldns_rdf_data(name), ldns_rdf_size(name));
66 	*tlsa_owner = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME,
67 			s + ldns_rdf_size(name), buf);
68 	if (*tlsa_owner == NULL) {
69 		return LDNS_STATUS_MEM_ERR;
70 	}
71 	return LDNS_STATUS_OK;
72 }
73 
74 
75 #ifdef HAVE_SSL
76 ldns_status
77 ldns_dane_cert2rdf(ldns_rdf** rdf, X509* cert,
78 		ldns_tlsa_selector      selector,
79 		ldns_tlsa_matching_type matching_type)
80 {
81 	unsigned char* buf = NULL;
82 	size_t len;
83 
84 	X509_PUBKEY* xpubkey;
85 	EVP_PKEY* epubkey;
86 
87 	unsigned char* digest;
88 
89 	assert(rdf != NULL);
90 	assert(cert != NULL);
91 
92 	switch(selector) {
93 	case LDNS_TLSA_SELECTOR_FULL_CERTIFICATE:
94 
95 		len = (size_t)i2d_X509(cert, &buf);
96 		break;
97 
98 	case LDNS_TLSA_SELECTOR_SUBJECTPUBLICKEYINFO:
99 
100 #ifndef S_SPLINT_S
101 		xpubkey = X509_get_X509_PUBKEY(cert);
102 #endif
103 		if (! xpubkey) {
104 			return LDNS_STATUS_SSL_ERR;
105 		}
106 		epubkey = X509_PUBKEY_get(xpubkey);
107 		if (! epubkey) {
108 			return LDNS_STATUS_SSL_ERR;
109 		}
110 		len = (size_t)i2d_PUBKEY(epubkey, &buf);
111 		break;
112 
113 	default:
114 		return LDNS_STATUS_DANE_UNKNOWN_SELECTOR;
115 	}
116 
117 	switch(matching_type) {
118 	case LDNS_TLSA_MATCHING_TYPE_NO_HASH_USED:
119 
120 		*rdf = ldns_rdf_new(LDNS_RDF_TYPE_HEX, len, buf);
121 
122 		return *rdf ? LDNS_STATUS_OK : LDNS_STATUS_MEM_ERR;
123 		break;
124 
125 	case LDNS_TLSA_MATCHING_TYPE_SHA256:
126 
127 		digest = LDNS_XMALLOC(unsigned char, LDNS_SHA256_DIGEST_LENGTH);
128 		if (digest == NULL) {
129 			LDNS_FREE(buf);
130 			return LDNS_STATUS_MEM_ERR;
131 		}
132 		(void) ldns_sha256(buf, (unsigned int)len, digest);
133 		*rdf = ldns_rdf_new(LDNS_RDF_TYPE_HEX, LDNS_SHA256_DIGEST_LENGTH,
134 				digest);
135 		LDNS_FREE(buf);
136 
137 		return *rdf ? LDNS_STATUS_OK : LDNS_STATUS_MEM_ERR;
138 		break;
139 
140 	case LDNS_TLSA_MATCHING_TYPE_SHA512:
141 
142 		digest = LDNS_XMALLOC(unsigned char, LDNS_SHA512_DIGEST_LENGTH);
143 		if (digest == NULL) {
144 			LDNS_FREE(buf);
145 			return LDNS_STATUS_MEM_ERR;
146 		}
147 		(void) ldns_sha512(buf, (unsigned int)len, digest);
148 		*rdf = ldns_rdf_new(LDNS_RDF_TYPE_HEX, LDNS_SHA512_DIGEST_LENGTH,
149 				digest);
150 		LDNS_FREE(buf);
151 
152 		return *rdf ? LDNS_STATUS_OK : LDNS_STATUS_MEM_ERR;
153 		break;
154 
155 	default:
156 		LDNS_FREE(buf);
157 		return LDNS_STATUS_DANE_UNKNOWN_MATCHING_TYPE;
158 	}
159 }
160 
161 
162 /* Ordinary PKIX validation of cert (with extra_certs to help)
163  * against the CA's in store
164  */
165 static ldns_status
166 ldns_dane_pkix_validate(X509* cert, STACK_OF(X509)* extra_certs,
167 		X509_STORE* store)
168 {
169 	X509_STORE_CTX* vrfy_ctx;
170 	ldns_status s;
171 
172 	if (! store) {
173 		return LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
174 	}
175 	vrfy_ctx = X509_STORE_CTX_new();
176 	if (! vrfy_ctx) {
177 
178 		return LDNS_STATUS_SSL_ERR;
179 
180 	} else if (X509_STORE_CTX_init(vrfy_ctx, store,
181 				cert, extra_certs) != 1) {
182 		s = LDNS_STATUS_SSL_ERR;
183 
184 	} else if (X509_verify_cert(vrfy_ctx) == 1) {
185 
186 		s = LDNS_STATUS_OK;
187 
188 	} else {
189 		s = LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
190 	}
191 	X509_STORE_CTX_free(vrfy_ctx);
192 	return s;
193 }
194 
195 
196 /* Orinary PKIX validation of cert (with extra_certs to help)
197  * against the CA's in store, but also return the validation chain.
198  */
199 static ldns_status
200 ldns_dane_pkix_validate_and_get_chain(STACK_OF(X509)** chain, X509* cert,
201 		STACK_OF(X509)* extra_certs, X509_STORE* store)
202 {
203 	ldns_status s;
204 	X509_STORE* empty_store = NULL;
205 	X509_STORE_CTX* vrfy_ctx;
206 
207 	assert(chain != NULL);
208 
209 	if (! store) {
210 		store = empty_store = X509_STORE_new();
211 	}
212 	s = LDNS_STATUS_SSL_ERR;
213 	vrfy_ctx = X509_STORE_CTX_new();
214 	if (! vrfy_ctx) {
215 
216 		goto exit_free_empty_store;
217 
218 	} else if (X509_STORE_CTX_init(vrfy_ctx, store,
219 					cert, extra_certs) != 1) {
220 		goto exit_free_vrfy_ctx;
221 
222 	} else if (X509_verify_cert(vrfy_ctx) == 1) {
223 
224 		s = LDNS_STATUS_OK;
225 
226 	} else {
227 		s = LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
228 	}
229 	*chain = X509_STORE_CTX_get1_chain(vrfy_ctx);
230 	if (! *chain) {
231 		s = LDNS_STATUS_SSL_ERR;
232 	}
233 
234 exit_free_vrfy_ctx:
235 	X509_STORE_CTX_free(vrfy_ctx);
236 
237 exit_free_empty_store:
238 	if (empty_store) {
239 		X509_STORE_free(empty_store);
240 	}
241 	return s;
242 }
243 
244 
245 /* Return the validation chain that can be build out of cert, with extra_certs.
246  */
247 static ldns_status
248 ldns_dane_pkix_get_chain(STACK_OF(X509)** chain,
249 		X509* cert, STACK_OF(X509)* extra_certs)
250 {
251 	ldns_status s;
252 	X509_STORE* empty_store = NULL;
253 	X509_STORE_CTX* vrfy_ctx;
254 
255 	assert(chain != NULL);
256 
257 	empty_store = X509_STORE_new();
258 	s = LDNS_STATUS_SSL_ERR;
259 	vrfy_ctx = X509_STORE_CTX_new();
260 	if (! vrfy_ctx) {
261 
262 		goto exit_free_empty_store;
263 
264 	} else if (X509_STORE_CTX_init(vrfy_ctx, empty_store,
265 					cert, extra_certs) != 1) {
266 		goto exit_free_vrfy_ctx;
267 	}
268 	(void) X509_verify_cert(vrfy_ctx);
269 	*chain = X509_STORE_CTX_get1_chain(vrfy_ctx);
270 	if (! *chain) {
271 		s = LDNS_STATUS_SSL_ERR;
272 	} else {
273 		s = LDNS_STATUS_OK;
274 	}
275 exit_free_vrfy_ctx:
276 	X509_STORE_CTX_free(vrfy_ctx);
277 
278 exit_free_empty_store:
279 	X509_STORE_free(empty_store);
280 	return s;
281 }
282 
283 
284 /* Pop n+1 certs and return the last popped.
285  */
286 static ldns_status
287 ldns_dane_get_nth_cert_from_validation_chain(
288 		X509** cert, STACK_OF(X509)* chain, int n, bool ca)
289 {
290 	if (n >= sk_X509_num(chain) || n < 0) {
291 		return LDNS_STATUS_DANE_OFFSET_OUT_OF_RANGE;
292 	}
293 	*cert = sk_X509_pop(chain);
294 	while (n-- > 0) {
295 		X509_free(*cert);
296 		*cert = sk_X509_pop(chain);
297 	}
298 	if (ca && ! X509_check_ca(*cert)) {
299 		return LDNS_STATUS_DANE_NON_CA_CERTIFICATE;
300 	}
301 	return LDNS_STATUS_OK;
302 }
303 
304 
305 /* Create validation chain with cert and extra_certs and returns the last
306  * self-signed (if present).
307  */
308 static ldns_status
309 ldns_dane_pkix_get_last_self_signed(X509** out_cert,
310 		X509* cert, STACK_OF(X509)* extra_certs)
311 {
312 	ldns_status s;
313 	X509_STORE* empty_store = NULL;
314 	X509_STORE_CTX* vrfy_ctx;
315 
316 	assert(out_cert != NULL);
317 
318 	empty_store = X509_STORE_new();
319 	s = LDNS_STATUS_SSL_ERR;
320 	vrfy_ctx = X509_STORE_CTX_new();
321 	if (! vrfy_ctx) {
322 		goto exit_free_empty_store;
323 
324 	} else if (X509_STORE_CTX_init(vrfy_ctx, empty_store,
325 					cert, extra_certs) != 1) {
326 		goto exit_free_vrfy_ctx;
327 
328 	}
329 	(void) X509_verify_cert(vrfy_ctx);
330 	if (vrfy_ctx->error == X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN ||
331 	    vrfy_ctx->error == X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT){
332 
333 		*out_cert = X509_STORE_CTX_get_current_cert( vrfy_ctx);
334 		s = LDNS_STATUS_OK;
335 	} else {
336 		s = LDNS_STATUS_DANE_PKIX_NO_SELF_SIGNED_TRUST_ANCHOR;
337 	}
338 exit_free_vrfy_ctx:
339 	X509_STORE_CTX_free(vrfy_ctx);
340 
341 exit_free_empty_store:
342 	X509_STORE_free(empty_store);
343 	return s;
344 }
345 
346 
347 ldns_status
348 ldns_dane_select_certificate(X509** selected_cert,
349 		X509* cert, STACK_OF(X509)* extra_certs,
350 		X509_STORE* pkix_validation_store,
351 		ldns_tlsa_certificate_usage cert_usage, int offset)
352 {
353 	ldns_status s;
354 	STACK_OF(X509)* pkix_validation_chain = NULL;
355 
356 	assert(selected_cert != NULL);
357 	assert(cert != NULL);
358 
359 	/* With PKIX validation explicitely turned off (pkix_validation_store
360 	 *  == NULL), treat the "CA constraint" and "Service certificate
361 	 * constraint" the same as "Trust anchor assertion" and "Domain issued
362 	 * certificate" respectively.
363 	 */
364 	if (pkix_validation_store == NULL) {
365 		switch (cert_usage) {
366 
367 		case LDNS_TLSA_USAGE_CA_CONSTRAINT:
368 
369 			cert_usage = LDNS_TLSA_USAGE_TRUST_ANCHOR_ASSERTION;
370 			break;
371 
372 		case LDNS_TLSA_USAGE_SERVICE_CERTIFICATE_CONSTRAINT:
373 
374 			cert_usage = LDNS_TLSA_USAGE_DOMAIN_ISSUED_CERTIFICATE;
375 			break;
376 
377 		default:
378 			break;
379 		}
380 	}
381 
382 	/* Now what to do with each Certificate usage...
383 	 */
384 	switch (cert_usage) {
385 
386 	case LDNS_TLSA_USAGE_CA_CONSTRAINT:
387 
388 		s = ldns_dane_pkix_validate_and_get_chain(
389 				&pkix_validation_chain,
390 				cert, extra_certs,
391 				pkix_validation_store);
392 		if (! pkix_validation_chain) {
393 			return s;
394 		}
395 		if (s == LDNS_STATUS_OK) {
396 			if (offset == -1) {
397 				offset = 0;
398 			}
399 			s = ldns_dane_get_nth_cert_from_validation_chain(
400 					selected_cert, pkix_validation_chain,
401 					offset, true);
402 		}
403 		sk_X509_pop_free(pkix_validation_chain, X509_free);
404 		return s;
405 		break;
406 
407 
408 	case LDNS_TLSA_USAGE_SERVICE_CERTIFICATE_CONSTRAINT:
409 
410 		*selected_cert = cert;
411 		return ldns_dane_pkix_validate(cert, extra_certs,
412 				pkix_validation_store);
413 		break;
414 
415 
416 	case LDNS_TLSA_USAGE_TRUST_ANCHOR_ASSERTION:
417 
418 		if (offset == -1) {
419 			s = ldns_dane_pkix_get_last_self_signed(
420 					selected_cert, cert, extra_certs);
421 			return s;
422 		} else {
423 			s = ldns_dane_pkix_get_chain(
424 					&pkix_validation_chain,
425 					cert, extra_certs);
426 			if (s == LDNS_STATUS_OK) {
427 				s =
428 				ldns_dane_get_nth_cert_from_validation_chain(
429 					selected_cert, pkix_validation_chain,
430 					offset, false);
431 			} else if (! pkix_validation_chain) {
432 				return s;
433 			}
434 			sk_X509_pop_free(pkix_validation_chain, X509_free);
435 			return s;
436 		}
437 		break;
438 
439 
440 	case LDNS_TLSA_USAGE_DOMAIN_ISSUED_CERTIFICATE:
441 
442 		*selected_cert = cert;
443 		return LDNS_STATUS_OK;
444 		break;
445 
446 	default:
447 		return LDNS_STATUS_DANE_UNKNOWN_CERTIFICATE_USAGE;
448 		break;
449 	}
450 }
451 
452 
453 ldns_status
454 ldns_dane_create_tlsa_rr(ldns_rr** tlsa,
455 		ldns_tlsa_certificate_usage certificate_usage,
456 		ldns_tlsa_selector          selector,
457 		ldns_tlsa_matching_type     matching_type,
458 		X509* cert)
459 {
460 	ldns_rdf* rdf;
461 	ldns_status s;
462 
463 	assert(tlsa != NULL);
464 	assert(cert != NULL);
465 
466 	/* create rr */
467 	*tlsa = ldns_rr_new_frm_type(LDNS_RR_TYPE_TLSA);
468 	if (*tlsa == NULL) {
469 		return LDNS_STATUS_MEM_ERR;
470 	}
471 
472 	rdf = ldns_native2rdf_int8(LDNS_RDF_TYPE_INT8,
473 			(uint8_t)certificate_usage);
474 	if (rdf == NULL) {
475 		goto memerror;
476 	}
477 	(void) ldns_rr_set_rdf(*tlsa, rdf, 0);
478 
479 	rdf = ldns_native2rdf_int8(LDNS_RDF_TYPE_INT8, (uint8_t)selector);
480 	if (rdf == NULL) {
481 		goto memerror;
482 	}
483 	(void) ldns_rr_set_rdf(*tlsa, rdf, 1);
484 
485 	rdf = ldns_native2rdf_int8(LDNS_RDF_TYPE_INT8, (uint8_t)matching_type);
486 	if (rdf == NULL) {
487 		goto memerror;
488 	}
489 	(void) ldns_rr_set_rdf(*tlsa, rdf, 2);
490 
491 	s = ldns_dane_cert2rdf(&rdf, cert, selector, matching_type);
492 	if (s == LDNS_STATUS_OK) {
493 		(void) ldns_rr_set_rdf(*tlsa, rdf, 3);
494 		return LDNS_STATUS_OK;
495 	}
496 	ldns_rr_free(*tlsa);
497 	*tlsa = NULL;
498 	return s;
499 
500 memerror:
501 	ldns_rr_free(*tlsa);
502 	*tlsa = NULL;
503 	return LDNS_STATUS_MEM_ERR;
504 }
505 
506 
507 /* Return tlsas that actually are TLSA resource records with known values
508  * for the Certificate usage, Selector and Matching type rdata fields.
509  */
510 static ldns_rr_list*
511 ldns_dane_filter_unusable_records(const ldns_rr_list* tlsas)
512 {
513 	size_t i;
514 	ldns_rr_list* r = ldns_rr_list_new();
515 	ldns_rr* tlsa_rr;
516 
517 	if (! r) {
518 		return NULL;
519 	}
520 	for (i = 0; i < ldns_rr_list_rr_count(tlsas); i++) {
521 		tlsa_rr = ldns_rr_list_rr(tlsas, i);
522 		if (ldns_rr_get_type(tlsa_rr) == LDNS_RR_TYPE_TLSA &&
523 		    ldns_rr_rd_count(tlsa_rr) == 4 &&
524 		    ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 0)) <= 3 &&
525 		    ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 1)) <= 1 &&
526 		    ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 2)) <= 2) {
527 
528 			if (! ldns_rr_list_push_rr(r, tlsa_rr)) {
529 				ldns_rr_list_free(r);
530 				return NULL;
531 			}
532 		}
533 	}
534 	return r;
535 }
536 
537 
538 /* Return whether cert/selector/matching_type matches data.
539  */
540 static ldns_status
541 ldns_dane_match_cert_with_data(X509* cert, ldns_tlsa_selector selector,
542 		ldns_tlsa_matching_type matching_type, ldns_rdf* data)
543 {
544 	ldns_status s;
545 	ldns_rdf* match_data;
546 
547 	s = ldns_dane_cert2rdf(&match_data, cert, selector, matching_type);
548 	if (s == LDNS_STATUS_OK) {
549 		if (ldns_rdf_compare(data, match_data) != 0) {
550 			s = LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH;
551 		}
552 		ldns_rdf_free(match_data);
553 	}
554 	return s;
555 }
556 
557 
558 /* Return whether any certificate from the chain with selector/matching_type
559  * matches data.
560  * ca should be true if the certificate has to be a CA certificate too.
561  */
562 static ldns_status
563 ldns_dane_match_any_cert_with_data(STACK_OF(X509)* chain,
564 		ldns_tlsa_selector      selector,
565 		ldns_tlsa_matching_type matching_type,
566 		ldns_rdf* data, bool ca)
567 {
568 	ldns_status s = LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH;
569 	size_t n, i;
570 	X509* cert;
571 
572 	n = (size_t)sk_X509_num(chain);
573 	for (i = 0; i < n; i++) {
574 		cert = sk_X509_pop(chain);
575 		if (! cert) {
576 			s = LDNS_STATUS_SSL_ERR;
577 			break;
578 		}
579 		s = ldns_dane_match_cert_with_data(cert,
580 				selector, matching_type, data);
581 		if (ca && s == LDNS_STATUS_OK && ! X509_check_ca(cert)) {
582 			s = LDNS_STATUS_DANE_NON_CA_CERTIFICATE;
583 		}
584 		X509_free(cert);
585 		if (s != LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH) {
586 			break;
587 		}
588 		/* when s == LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH,
589 		 * try to match the next certificate
590 		 */
591 	}
592 	return s;
593 }
594 
595 
596 ldns_status
597 ldns_dane_verify_rr(const ldns_rr* tlsa_rr,
598 		X509* cert, STACK_OF(X509)* extra_certs,
599 		X509_STORE* pkix_validation_store)
600 {
601 	ldns_status s;
602 
603 	STACK_OF(X509)* pkix_validation_chain = NULL;
604 
605 	ldns_tlsa_certificate_usage cert_usage;
606 	ldns_tlsa_selector          selector;
607 	ldns_tlsa_matching_type     matching_type;
608 	ldns_rdf*                   data;
609 
610 	if (! tlsa_rr) {
611 		/* No TLSA, so regular PKIX validation
612 		 */
613 		return ldns_dane_pkix_validate(cert, extra_certs,
614 				pkix_validation_store);
615 	}
616 	cert_usage    = ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 0));
617 	selector      = ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 1));
618 	matching_type = ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 2));
619 	data          =                      ldns_rr_rdf(tlsa_rr, 3) ;
620 
621 	switch (cert_usage) {
622 	case LDNS_TLSA_USAGE_CA_CONSTRAINT:
623 		s = ldns_dane_pkix_validate_and_get_chain(
624 				&pkix_validation_chain,
625 				cert, extra_certs,
626 				pkix_validation_store);
627 		if (! pkix_validation_chain) {
628 			return s;
629 		}
630 		if (s == LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE) {
631 			/*
632 			 * NO PKIX validation. We still try to match *any*
633 			 * certificate from the chain, so we return
634 			 * TLSA errors over PKIX errors.
635 			 *
636 			 * i.e. When the TLSA matches no certificate, we return
637 			 * TLSA_DID_NOT_MATCH and not PKIX_DID_NOT_VALIDATE
638 			 */
639 			s = ldns_dane_match_any_cert_with_data(
640 					pkix_validation_chain,
641 					selector, matching_type, data, true);
642 
643 			if (s == LDNS_STATUS_OK) {
644 				/* A TLSA record did match a cert from the
645 				 * chain, thus the error is failed PKIX
646 				 * validation.
647 				 */
648 				s = LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
649 			}
650 
651 		} else if (s == LDNS_STATUS_OK) {
652 			/* PKIX validated, does the TLSA match too? */
653 
654 			s = ldns_dane_match_any_cert_with_data(
655 					pkix_validation_chain,
656 					selector, matching_type, data, true);
657 		}
658 		sk_X509_pop_free(pkix_validation_chain, X509_free);
659 		return s;
660 		break;
661 
662 	case LDNS_TLSA_USAGE_SERVICE_CERTIFICATE_CONSTRAINT:
663 		s = ldns_dane_match_cert_with_data(cert,
664 				selector, matching_type, data);
665 
666 		if (s == LDNS_STATUS_OK) {
667 			return ldns_dane_pkix_validate(cert, extra_certs,
668 					pkix_validation_store);
669 		}
670 		return s;
671 		break;
672 
673 	case LDNS_TLSA_USAGE_TRUST_ANCHOR_ASSERTION:
674 		s = ldns_dane_pkix_get_chain(&pkix_validation_chain,
675 				cert, extra_certs);
676 
677 		if (s == LDNS_STATUS_OK) {
678 			s = ldns_dane_match_any_cert_with_data(
679 					pkix_validation_chain,
680 					selector, matching_type, data, false);
681 
682 		} else if (! pkix_validation_chain) {
683 			return s;
684 		}
685 		sk_X509_pop_free(pkix_validation_chain, X509_free);
686 		return s;
687 		break;
688 
689 	case LDNS_TLSA_USAGE_DOMAIN_ISSUED_CERTIFICATE:
690 		return ldns_dane_match_cert_with_data(cert,
691 				selector, matching_type, data);
692 		break;
693 
694 	default:
695 		break;
696 	}
697 	return LDNS_STATUS_DANE_UNKNOWN_CERTIFICATE_USAGE;
698 }
699 
700 
701 ldns_status
702 ldns_dane_verify(ldns_rr_list* tlsas,
703 		X509* cert, STACK_OF(X509)* extra_certs,
704 		X509_STORE* pkix_validation_store)
705 {
706 	size_t i;
707 	ldns_rr* tlsa_rr;
708 	ldns_status s = LDNS_STATUS_OK, ps;
709 
710 	assert(cert != NULL);
711 
712 	if (tlsas && ldns_rr_list_rr_count(tlsas) > 0) {
713 		tlsas = ldns_dane_filter_unusable_records(tlsas);
714 		if (! tlsas) {
715 			return LDNS_STATUS_MEM_ERR;
716 		}
717 	}
718 	if (! tlsas || ldns_rr_list_rr_count(tlsas) == 0) {
719 		/* No TLSA's, so regular PKIX validation
720 		 */
721 		return ldns_dane_pkix_validate(cert, extra_certs,
722 				pkix_validation_store);
723 	} else {
724 		for (i = 0; i < ldns_rr_list_rr_count(tlsas); i++) {
725 			tlsa_rr = ldns_rr_list_rr(tlsas, i);
726 			ps = s;
727 			s = ldns_dane_verify_rr(tlsa_rr, cert, extra_certs,
728 					pkix_validation_store);
729 
730 			if (s != LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH &&
731 			    s != LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE) {
732 
733 				/* which would be LDNS_STATUS_OK (match)
734 				 * or some fatal error preventing use from
735 				 * trying the next TLSA record.
736 				 */
737 				break;
738 			}
739 			s = (s > ps ? s : ps); /* prefer PKIX_DID_NOT_VALIDATE
740 						* over   TLSA_DID_NOT_MATCH
741 						*/
742 		}
743 		ldns_rr_list_free(tlsas);
744 	}
745 	return s;
746 }
747 #endif /* HAVE_SSL */
748 #endif /* USE_DANE */
749