1 /* $OpenBSD: ocsp_vfy.c,v 1.24 2024/07/12 18:15:10 beck Exp $ */
2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
3 * project 2000.
4 */
5 /* ====================================================================
6 * Copyright (c) 2000-2004 The OpenSSL Project. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * licensing@OpenSSL.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 * acknowledgment:
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 *
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
56 *
57 */
58
59 #include <openssl/ocsp.h>
60 #include <openssl/err.h>
61 #include <string.h>
62
63 #include "ocsp_local.h"
64 #include "x509_local.h"
65
66 static int ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs,
67 STACK_OF(X509) *certs, X509_STORE *st, unsigned long flags);
68 static X509 *ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id);
69 static int ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain,
70 unsigned long flags);
71 static int ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret);
72 static int ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid,
73 STACK_OF(OCSP_SINGLERESP) *sresp);
74 static int ocsp_check_delegated(X509 *x, int flags);
75 static int ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req,
76 X509_NAME *nm, STACK_OF(X509) *certs, X509_STORE *st,
77 unsigned long flags);
78
79 /* Verify a basic response message */
80 int
OCSP_basic_verify(OCSP_BASICRESP * bs,STACK_OF (X509)* certs,X509_STORE * st,unsigned long flags)81 OCSP_basic_verify(OCSP_BASICRESP *bs, STACK_OF(X509) *certs, X509_STORE *st,
82 unsigned long flags)
83 {
84 X509 *signer, *x;
85 STACK_OF(X509) *chain = NULL;
86 STACK_OF(X509) *untrusted = NULL;
87 X509_STORE_CTX ctx;
88 int i, ret = 0;
89
90 ret = ocsp_find_signer(&signer, bs, certs, st, flags);
91 if (!ret) {
92 OCSPerror(OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
93 goto end;
94 }
95 if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
96 flags |= OCSP_NOVERIFY;
97 if (!(flags & OCSP_NOSIGS)) {
98 EVP_PKEY *skey;
99
100 skey = X509_get0_pubkey(signer);
101 if (skey) {
102 ret = OCSP_BASICRESP_verify(bs, skey, 0);
103 }
104 if (!skey || ret <= 0) {
105 OCSPerror(OCSP_R_SIGNATURE_FAILURE);
106 goto end;
107 }
108 }
109 if (!(flags & OCSP_NOVERIFY)) {
110 int init_res;
111
112 if (flags & OCSP_NOCHAIN) {
113 untrusted = NULL;
114 } else if (bs->certs && certs) {
115 untrusted = sk_X509_dup(bs->certs);
116 for (i = 0; i < sk_X509_num(certs); i++) {
117 if (!sk_X509_push(untrusted,
118 sk_X509_value(certs, i))) {
119 OCSPerror(ERR_R_MALLOC_FAILURE);
120 goto end;
121 }
122 }
123 } else if (certs != NULL) {
124 untrusted = certs;
125 } else {
126 untrusted = bs->certs;
127 }
128 init_res = X509_STORE_CTX_init(&ctx, st, signer, untrusted);
129 if (!init_res) {
130 ret = -1;
131 OCSPerror(ERR_R_X509_LIB);
132 goto end;
133 }
134
135 if (X509_STORE_CTX_set_purpose(&ctx,
136 X509_PURPOSE_OCSP_HELPER) == 0) {
137 X509_STORE_CTX_cleanup(&ctx);
138 ret = -1;
139 goto end;
140 }
141 ret = X509_verify_cert(&ctx);
142 chain = X509_STORE_CTX_get1_chain(&ctx);
143 X509_STORE_CTX_cleanup(&ctx);
144 if (ret <= 0) {
145 i = X509_STORE_CTX_get_error(&ctx);
146 OCSPerror(OCSP_R_CERTIFICATE_VERIFY_ERROR);
147 ERR_asprintf_error_data("Verify error:%s",
148 X509_verify_cert_error_string(i));
149 goto end;
150 }
151 if (flags & OCSP_NOCHECKS) {
152 ret = 1;
153 goto end;
154 }
155 /* At this point we have a valid certificate chain
156 * need to verify it against the OCSP issuer criteria.
157 */
158 ret = ocsp_check_issuer(bs, chain, flags);
159
160 /* If fatal error or valid match then finish */
161 if (ret != 0)
162 goto end;
163
164 /* Easy case: explicitly trusted. Get root CA and
165 * check for explicit trust
166 */
167 if (flags & OCSP_NOEXPLICIT)
168 goto end;
169
170 x = sk_X509_value(chain, sk_X509_num(chain) - 1);
171 if (X509_check_trust(x, X509_TRUST_OCSP_SIGN, 0) !=
172 X509_TRUST_TRUSTED) {
173 OCSPerror(OCSP_R_ROOT_CA_NOT_TRUSTED);
174 goto end;
175 }
176 ret = 1;
177 }
178
179 end:
180 if (chain)
181 sk_X509_pop_free(chain, X509_free);
182 if (bs->certs && certs)
183 sk_X509_free(untrusted);
184 return ret;
185 }
186 LCRYPTO_ALIAS(OCSP_basic_verify);
187
188 int
OCSP_resp_get0_signer(OCSP_BASICRESP * bs,X509 ** signer,STACK_OF (X509)* extra_certs)189 OCSP_resp_get0_signer(OCSP_BASICRESP *bs, X509 **signer,
190 STACK_OF(X509) *extra_certs)
191 {
192 return ocsp_find_signer(signer, bs, extra_certs, NULL, 0) > 0;
193 }
194 LCRYPTO_ALIAS(OCSP_resp_get0_signer);
195
196 static int
ocsp_find_signer(X509 ** psigner,OCSP_BASICRESP * bs,STACK_OF (X509)* certs,X509_STORE * st,unsigned long flags)197 ocsp_find_signer(X509 **psigner, OCSP_BASICRESP *bs, STACK_OF(X509) *certs,
198 X509_STORE *st, unsigned long flags)
199 {
200 X509 *signer;
201 OCSP_RESPID *rid = bs->tbsResponseData->responderId;
202
203 if ((signer = ocsp_find_signer_sk(certs, rid))) {
204 *psigner = signer;
205 return 2;
206 }
207 if (!(flags & OCSP_NOINTERN) &&
208 (signer = ocsp_find_signer_sk(bs->certs, rid))) {
209 *psigner = signer;
210 return 1;
211 }
212 /* Maybe lookup from store if by subject name */
213
214 *psigner = NULL;
215 return 0;
216 }
217
218 static X509 *
ocsp_find_signer_sk(STACK_OF (X509)* certs,OCSP_RESPID * id)219 ocsp_find_signer_sk(STACK_OF(X509) *certs, OCSP_RESPID *id)
220 {
221 int i;
222 unsigned char tmphash[SHA_DIGEST_LENGTH], *keyhash;
223 X509 *x;
224
225 /* Easy if lookup by name */
226 if (id->type == V_OCSP_RESPID_NAME)
227 return X509_find_by_subject(certs, id->value.byName);
228
229 /* Lookup by key hash */
230
231 /* If key hash isn't SHA1 length then forget it */
232 if (id->value.byKey->length != SHA_DIGEST_LENGTH)
233 return NULL;
234 keyhash = id->value.byKey->data;
235 /* Calculate hash of each key and compare */
236 for (i = 0; i < sk_X509_num(certs); i++) {
237 x = sk_X509_value(certs, i);
238 X509_pubkey_digest(x, EVP_sha1(), tmphash, NULL);
239 if (!memcmp(keyhash, tmphash, SHA_DIGEST_LENGTH))
240 return x;
241 }
242 return NULL;
243 }
244
245 static int
ocsp_check_issuer(OCSP_BASICRESP * bs,STACK_OF (X509)* chain,unsigned long flags)246 ocsp_check_issuer(OCSP_BASICRESP *bs, STACK_OF(X509) *chain,
247 unsigned long flags)
248 {
249 STACK_OF(OCSP_SINGLERESP) *sresp;
250 X509 *signer, *sca;
251 OCSP_CERTID *caid = NULL;
252 int i;
253
254 sresp = bs->tbsResponseData->responses;
255
256 if (sk_X509_num(chain) <= 0) {
257 OCSPerror(OCSP_R_NO_CERTIFICATES_IN_CHAIN);
258 return -1;
259 }
260
261 /* See if the issuer IDs match. */
262 i = ocsp_check_ids(sresp, &caid);
263
264 /* If ID mismatch or other error then return */
265 if (i <= 0)
266 return i;
267
268 signer = sk_X509_value(chain, 0);
269 /* Check to see if OCSP responder CA matches request CA */
270 if (sk_X509_num(chain) > 1) {
271 sca = sk_X509_value(chain, 1);
272 i = ocsp_match_issuerid(sca, caid, sresp);
273 if (i < 0)
274 return i;
275 if (i) {
276 /* We have a match, if extensions OK then success */
277 if (ocsp_check_delegated(signer, flags))
278 return 1;
279 return 0;
280 }
281 }
282
283 /* Otherwise check if OCSP request signed directly by request CA */
284 return ocsp_match_issuerid(signer, caid, sresp);
285 }
286
287 /* Check the issuer certificate IDs for equality. If there is a mismatch with the same
288 * algorithm then there's no point trying to match any certificates against the issuer.
289 * If the issuer IDs all match then we just need to check equality against one of them.
290 */
291 static int
ocsp_check_ids(STACK_OF (OCSP_SINGLERESP)* sresp,OCSP_CERTID ** ret)292 ocsp_check_ids(STACK_OF(OCSP_SINGLERESP) *sresp, OCSP_CERTID **ret)
293 {
294 OCSP_CERTID *tmpid, *cid;
295 int i, idcount;
296
297 idcount = sk_OCSP_SINGLERESP_num(sresp);
298 if (idcount <= 0) {
299 OCSPerror(OCSP_R_RESPONSE_CONTAINS_NO_REVOCATION_DATA);
300 return -1;
301 }
302
303 cid = sk_OCSP_SINGLERESP_value(sresp, 0)->certId;
304
305 *ret = NULL;
306
307 for (i = 1; i < idcount; i++) {
308 tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
309 /* Check to see if IDs match */
310 if (OCSP_id_issuer_cmp(cid, tmpid)) {
311 return 0;
312 }
313 }
314
315 /* All IDs match: only need to check one ID */
316 *ret = cid;
317 return 1;
318 }
319
320 static int
ocsp_match_issuerid(X509 * cert,OCSP_CERTID * cid,STACK_OF (OCSP_SINGLERESP)* sresp)321 ocsp_match_issuerid(X509 *cert, OCSP_CERTID *cid,
322 STACK_OF(OCSP_SINGLERESP) *sresp)
323 {
324 /* If only one ID to match then do it */
325 if (cid) {
326 const EVP_MD *dgst;
327 X509_NAME *iname;
328 int mdlen;
329 unsigned char md[EVP_MAX_MD_SIZE];
330
331 if (!(dgst =
332 EVP_get_digestbyobj(cid->hashAlgorithm->algorithm))) {
333 OCSPerror(OCSP_R_UNKNOWN_MESSAGE_DIGEST);
334 return -1;
335 }
336
337 mdlen = EVP_MD_size(dgst);
338 if (mdlen < 0)
339 return -1;
340 if (cid->issuerNameHash->length != mdlen ||
341 cid->issuerKeyHash->length != mdlen)
342 return 0;
343 iname = X509_get_subject_name(cert);
344 if (!X509_NAME_digest(iname, dgst, md, NULL))
345 return -1;
346 if (memcmp(md, cid->issuerNameHash->data, mdlen))
347 return 0;
348 X509_pubkey_digest(cert, dgst, md, NULL);
349 if (memcmp(md, cid->issuerKeyHash->data, mdlen))
350 return 0;
351
352 return 1;
353 } else {
354 /* We have to match the whole lot */
355 int i, ret;
356 OCSP_CERTID *tmpid;
357
358 for (i = 0; i < sk_OCSP_SINGLERESP_num(sresp); i++) {
359 tmpid = sk_OCSP_SINGLERESP_value(sresp, i)->certId;
360 ret = ocsp_match_issuerid(cert, tmpid, NULL);
361 if (ret <= 0)
362 return ret;
363 }
364 return 1;
365 }
366 }
367
368 static int
ocsp_check_delegated(X509 * x,int flags)369 ocsp_check_delegated(X509 *x, int flags)
370 {
371 X509_check_purpose(x, -1, 0);
372 if ((x->ex_flags & EXFLAG_XKUSAGE) && (x->ex_xkusage & XKU_OCSP_SIGN))
373 return 1;
374 OCSPerror(OCSP_R_MISSING_OCSPSIGNING_USAGE);
375 return 0;
376 }
377
378 /* Verify an OCSP request. This is fortunately much easier than OCSP
379 * response verify. Just find the signers certificate and verify it
380 * against a given trust value.
381 */
382 int
OCSP_request_verify(OCSP_REQUEST * req,STACK_OF (X509)* certs,X509_STORE * store,unsigned long flags)383 OCSP_request_verify(OCSP_REQUEST *req, STACK_OF(X509) *certs, X509_STORE *store,
384 unsigned long flags)
385 {
386 X509 *signer;
387 X509_NAME *nm;
388 GENERAL_NAME *gen;
389 int ret;
390 X509_STORE_CTX ctx;
391
392 if (!req->optionalSignature) {
393 OCSPerror(OCSP_R_REQUEST_NOT_SIGNED);
394 return 0;
395 }
396 gen = req->tbsRequest->requestorName;
397 if (!gen || gen->type != GEN_DIRNAME) {
398 OCSPerror(OCSP_R_UNSUPPORTED_REQUESTORNAME_TYPE);
399 return 0;
400 }
401 nm = gen->d.directoryName;
402 ret = ocsp_req_find_signer(&signer, req, nm, certs, store, flags);
403 if (ret <= 0) {
404 OCSPerror(OCSP_R_SIGNER_CERTIFICATE_NOT_FOUND);
405 return 0;
406 }
407 if ((ret == 2) && (flags & OCSP_TRUSTOTHER))
408 flags |= OCSP_NOVERIFY;
409 if (!(flags & OCSP_NOSIGS)) {
410 EVP_PKEY *skey;
411
412 if ((skey = X509_get0_pubkey(signer)) == NULL)
413 return 0;
414 ret = OCSP_REQUEST_verify(req, skey);
415 if (ret <= 0) {
416 OCSPerror(OCSP_R_SIGNATURE_FAILURE);
417 return 0;
418 }
419 }
420 if (!(flags & OCSP_NOVERIFY)) {
421 int init_res;
422
423 if (flags & OCSP_NOCHAIN)
424 init_res = X509_STORE_CTX_init(&ctx, store, signer,
425 NULL);
426 else
427 init_res = X509_STORE_CTX_init(&ctx, store, signer,
428 req->optionalSignature->certs);
429 if (!init_res) {
430 OCSPerror(ERR_R_X509_LIB);
431 return 0;
432 }
433
434 if (X509_STORE_CTX_set_purpose(&ctx,
435 X509_PURPOSE_OCSP_HELPER) == 0 ||
436 X509_STORE_CTX_set_trust(&ctx,
437 X509_TRUST_OCSP_REQUEST) == 0) {
438 X509_STORE_CTX_cleanup(&ctx);
439 return 0;
440 }
441 ret = X509_verify_cert(&ctx);
442 X509_STORE_CTX_cleanup(&ctx);
443 if (ret <= 0) {
444 ret = X509_STORE_CTX_get_error(&ctx);
445 OCSPerror(OCSP_R_CERTIFICATE_VERIFY_ERROR);
446 ERR_asprintf_error_data("Verify error:%s",
447 X509_verify_cert_error_string(ret));
448 return 0;
449 }
450 }
451 return 1;
452 }
453 LCRYPTO_ALIAS(OCSP_request_verify);
454
455 static int
ocsp_req_find_signer(X509 ** psigner,OCSP_REQUEST * req,X509_NAME * nm,STACK_OF (X509)* certs,X509_STORE * st,unsigned long flags)456 ocsp_req_find_signer(X509 **psigner, OCSP_REQUEST *req, X509_NAME *nm,
457 STACK_OF(X509) *certs, X509_STORE *st, unsigned long flags)
458 {
459 X509 *signer;
460
461 if (!(flags & OCSP_NOINTERN)) {
462 signer = X509_find_by_subject(req->optionalSignature->certs, nm);
463 if (signer) {
464 *psigner = signer;
465 return 1;
466 }
467 }
468
469 signer = X509_find_by_subject(certs, nm);
470 if (signer) {
471 *psigner = signer;
472 return 2;
473 }
474 return 0;
475 }
476