Purpose and trust setting functions for X509_STORE.
[openssl.git] / crypto / x509v3 / v3_purp.c
1 /* v3_purp.c */
2 /* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
3  * project 1999.
4  */
5 /* ====================================================================
6  * Copyright (c) 1999 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,
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46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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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 <stdio.h>
60 #include "cryptlib.h"
61 #include <openssl/x509v3.h>
62 #include <openssl/x509_vfy.h>
63
64 static void x509v3_cache_extensions(X509 *x);
65
66 static int ca_check(const X509 *x);
67 static int check_ssl_ca(const X509 *x);
68 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca);
69 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
70 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
71 static int purpose_smime(const X509 *x, int ca);
72 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
73 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca);
74 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
75 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca);
76 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca);
77
78 static int xp_cmp(const X509_PURPOSE * const *a,
79                 const X509_PURPOSE * const *b);
80 static void xptable_free(X509_PURPOSE *p);
81
82 static X509_PURPOSE xstandard[] = {
83         {X509_PURPOSE_SSL_CLIENT, X509_TRUST_SSL_CLIENT, 0, check_purpose_ssl_client, "SSL client", "sslclient", NULL},
84         {X509_PURPOSE_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ssl_server, "SSL server", "sslserver", NULL},
85         {X509_PURPOSE_NS_SSL_SERVER, X509_TRUST_SSL_SERVER, 0, check_purpose_ns_ssl_server, "Netscape SSL server", "nssslserver", NULL},
86         {X509_PURPOSE_SMIME_SIGN, X509_TRUST_EMAIL, 0, check_purpose_smime_sign, "S/MIME signing", "smimesign", NULL},
87         {X509_PURPOSE_SMIME_ENCRYPT, X509_TRUST_EMAIL, 0, check_purpose_smime_encrypt, "S/MIME encryption", "smimeencrypt", NULL},
88         {X509_PURPOSE_CRL_SIGN, X509_TRUST_COMPAT, 0, check_purpose_crl_sign, "CRL signing", "crlsign", NULL},
89         {X509_PURPOSE_ANY, X509_TRUST_DEFAULT, 0, no_check, "Any Purpose", "any", NULL},
90         {X509_PURPOSE_OCSP_HELPER, X509_TRUST_COMPAT, 0, ocsp_helper, "OCSP helper", "ocsphelper", NULL},
91 };
92
93 #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))
94
95 IMPLEMENT_STACK_OF(X509_PURPOSE)
96
97 static STACK_OF(X509_PURPOSE) *xptable = NULL;
98
99 static int xp_cmp(const X509_PURPOSE * const *a,
100                 const X509_PURPOSE * const *b)
101 {
102         return (*a)->purpose - (*b)->purpose;
103 }
104
105 /* As much as I'd like to make X509_check_purpose use a "const" X509*
106  * I really can't because it does recalculate hashes and do other non-const
107  * things. */
108 int X509_check_purpose(X509 *x, int id, int ca)
109 {
110         int idx;
111         const X509_PURPOSE *pt;
112         if(!(x->ex_flags & EXFLAG_SET)) {
113                 CRYPTO_w_lock(CRYPTO_LOCK_X509);
114                 x509v3_cache_extensions(x);
115                 CRYPTO_w_unlock(CRYPTO_LOCK_X509);
116         }
117         if(id == -1) return 1;
118         idx = X509_PURPOSE_get_by_id(id);
119         if(idx == -1) return -1;
120         pt = X509_PURPOSE_get0(idx);
121         return pt->check_purpose(pt, x, ca);
122 }
123
124 int X509_PURPOSE_set(int *p, int purpose)
125 {
126         if(X509_PURPOSE_get_by_id(purpose) == -1) {
127                 X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
128                 return 0;
129         }
130         *p = purpose;
131         return 1;
132 }
133
134 int X509_PURPOSE_get_count(void)
135 {
136         if(!xptable) return X509_PURPOSE_COUNT;
137         return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
138 }
139
140 X509_PURPOSE * X509_PURPOSE_get0(int idx)
141 {
142         if(idx < 0) return NULL;
143         if(idx < X509_PURPOSE_COUNT) return xstandard + idx;
144         return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
145 }
146
147 int X509_PURPOSE_get_by_sname(char *sname)
148 {
149         int i;
150         X509_PURPOSE *xptmp;
151         for(i = 0; i < X509_PURPOSE_get_count(); i++) {
152                 xptmp = X509_PURPOSE_get0(i);
153                 if(!strcmp(xptmp->sname, sname)) return i;
154         }
155         return -1;
156 }
157
158 int X509_PURPOSE_get_by_id(int purpose)
159 {
160         X509_PURPOSE tmp;
161         int idx;
162         if((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
163                 return purpose - X509_PURPOSE_MIN;
164         tmp.purpose = purpose;
165         if(!xptable) return -1;
166         idx = sk_X509_PURPOSE_find(xptable, &tmp);
167         if(idx == -1) return -1;
168         return idx + X509_PURPOSE_COUNT;
169 }
170
171 int X509_PURPOSE_add(int id, int trust, int flags,
172                         int (*ck)(const X509_PURPOSE *, const X509 *, int),
173                                         char *name, char *sname, void *arg)
174 {
175         int idx;
176         X509_PURPOSE *ptmp;
177         /* This is set according to what we change: application can't set it */
178         flags &= ~X509_PURPOSE_DYNAMIC;
179         /* This will always be set for application modified trust entries */
180         flags |= X509_PURPOSE_DYNAMIC_NAME;
181         /* Get existing entry if any */
182         idx = X509_PURPOSE_get_by_id(id);
183         /* Need a new entry */
184         if(idx == -1) {
185                 if(!(ptmp = OPENSSL_malloc(sizeof(X509_PURPOSE)))) {
186                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
187                         return 0;
188                 }
189                 ptmp->flags = X509_PURPOSE_DYNAMIC;
190         } else ptmp = X509_PURPOSE_get0(idx);
191
192         /* OPENSSL_free existing name if dynamic */
193         if(ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
194                 OPENSSL_free(ptmp->name);
195                 OPENSSL_free(ptmp->sname);
196         }
197         /* dup supplied name */
198         ptmp->name = BUF_strdup(name);
199         ptmp->sname = BUF_strdup(sname);
200         if(!ptmp->name || !ptmp->sname) {
201                 X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
202                 return 0;
203         }
204         /* Keep the dynamic flag of existing entry */
205         ptmp->flags &= X509_PURPOSE_DYNAMIC;
206         /* Set all other flags */
207         ptmp->flags |= flags;
208
209         ptmp->purpose = id;
210         ptmp->trust = trust;
211         ptmp->check_purpose = ck;
212         ptmp->usr_data = arg;
213
214         /* If its a new entry manage the dynamic table */
215         if(idx == -1) {
216                 if(!xptable && !(xptable = sk_X509_PURPOSE_new(xp_cmp))) {
217                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
218                         return 0;
219                 }
220                 if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
221                         X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
222                         return 0;
223                 }
224         }
225         return 1;
226 }
227
228 static void xptable_free(X509_PURPOSE *p)
229         {
230         if(!p) return;
231         if (p->flags & X509_PURPOSE_DYNAMIC) 
232                 {
233                 if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
234                         OPENSSL_free(p->name);
235                         OPENSSL_free(p->sname);
236                 }
237                 OPENSSL_free(p);
238                 }
239         }
240
241 void X509_PURPOSE_cleanup(void)
242 {
243         int i;
244         sk_X509_PURPOSE_pop_free(xptable, xptable_free);
245         for(i = 0; i < X509_PURPOSE_COUNT; i++) xptable_free(xstandard + i);
246         xptable = NULL;
247 }
248
249 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
250 {
251         return xp->purpose;
252 }
253
254 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
255 {
256         return xp->name;
257 }
258
259 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
260 {
261         return xp->sname;
262 }
263
264 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
265 {
266         return xp->trust;
267 }
268
269 static void x509v3_cache_extensions(X509 *x)
270 {
271         BASIC_CONSTRAINTS *bs;
272         ASN1_BIT_STRING *usage;
273         ASN1_BIT_STRING *ns;
274         EXTENDED_KEY_USAGE *extusage;
275         
276         int i;
277         if(x->ex_flags & EXFLAG_SET) return;
278 #ifndef OPENSSL_NO_SHA
279         X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
280 #endif
281         /* Does subject name match issuer ? */
282         if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
283                          x->ex_flags |= EXFLAG_SS;
284         /* V1 should mean no extensions ... */
285         if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
286         /* Handle basic constraints */
287         if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
288                 if(bs->ca) x->ex_flags |= EXFLAG_CA;
289                 if(bs->pathlen) {
290                         if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
291                                                 || !bs->ca) {
292                                 x->ex_flags |= EXFLAG_INVALID;
293                                 x->ex_pathlen = 0;
294                         } else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
295                 } else x->ex_pathlen = -1;
296                 BASIC_CONSTRAINTS_free(bs);
297                 x->ex_flags |= EXFLAG_BCONS;
298         }
299         /* Handle key usage */
300         if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
301                 if(usage->length > 0) {
302                         x->ex_kusage = usage->data[0];
303                         if(usage->length > 1) 
304                                 x->ex_kusage |= usage->data[1] << 8;
305                 } else x->ex_kusage = 0;
306                 x->ex_flags |= EXFLAG_KUSAGE;
307                 ASN1_BIT_STRING_free(usage);
308         }
309         x->ex_xkusage = 0;
310         if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
311                 x->ex_flags |= EXFLAG_XKUSAGE;
312                 for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
313                         switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
314                                 case NID_server_auth:
315                                 x->ex_xkusage |= XKU_SSL_SERVER;
316                                 break;
317
318                                 case NID_client_auth:
319                                 x->ex_xkusage |= XKU_SSL_CLIENT;
320                                 break;
321
322                                 case NID_email_protect:
323                                 x->ex_xkusage |= XKU_SMIME;
324                                 break;
325
326                                 case NID_code_sign:
327                                 x->ex_xkusage |= XKU_CODE_SIGN;
328                                 break;
329
330                                 case NID_ms_sgc:
331                                 case NID_ns_sgc:
332                                 x->ex_xkusage |= XKU_SGC;
333                                 break;
334
335                                 case NID_OCSP_sign:
336                                 x->ex_xkusage |= XKU_OCSP_SIGN;
337                                 break;
338
339                                 case NID_time_stamp:
340                                 x->ex_xkusage |= XKU_TIMESTAMP;
341                                 break;
342                         }
343                 }
344                 sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
345         }
346
347         if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
348                 if(ns->length > 0) x->ex_nscert = ns->data[0];
349                 else x->ex_nscert = 0;
350                 x->ex_flags |= EXFLAG_NSCERT;
351                 ASN1_BIT_STRING_free(ns);
352         }
353         x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
354         x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
355         x->ex_flags |= EXFLAG_SET;
356 }
357
358 /* CA checks common to all purposes
359  * return codes:
360  * 0 not a CA
361  * 1 is a CA
362  * 2 basicConstraints absent so "maybe" a CA
363  * 3 basicConstraints absent but self signed V1.
364  */
365
366 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
367 #define ku_reject(x, usage) \
368         (((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
369 #define xku_reject(x, usage) \
370         (((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
371 #define ns_reject(x, usage) \
372         (((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
373
374 static int ca_check(const X509 *x)
375 {
376         /* keyUsage if present should allow cert signing */
377         if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
378         if(x->ex_flags & EXFLAG_BCONS) {
379                 if(x->ex_flags & EXFLAG_CA) return 1;
380                 /* If basicConstraints says not a CA then say so */
381                 else return 0;
382         } else {
383                 if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
384                 /* If key usage present it must have certSign so tolerate it */
385                 else if (x->ex_flags & EXFLAG_KUSAGE) return 3;
386                 else return 2;
387         }
388 }
389
390 /* Check SSL CA: common checks for SSL client and server */
391 static int check_ssl_ca(const X509 *x)
392 {
393         int ca_ret;
394         ca_ret = ca_check(x);
395         if(!ca_ret) return 0;
396         /* check nsCertType if present */
397         if(x->ex_flags & EXFLAG_NSCERT) {
398                 if(x->ex_nscert & NS_SSL_CA) return ca_ret;
399                 return 0;
400         }
401         if(ca_ret != 2) return ca_ret;
402         else return 0;
403 }
404
405
406 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
407 {
408         if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
409         if(ca) return check_ssl_ca(x);
410         /* We need to do digital signatures with it */
411         if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
412         /* nsCertType if present should allow SSL client use */ 
413         if(ns_reject(x, NS_SSL_CLIENT)) return 0;
414         return 1;
415 }
416
417 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
418 {
419         if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
420         if(ca) return check_ssl_ca(x);
421
422         if(ns_reject(x, NS_SSL_SERVER)) return 0;
423         /* Now as for keyUsage: we'll at least need to sign OR encipher */
424         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
425         
426         return 1;
427
428 }
429
430 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
431 {
432         int ret;
433         ret = check_purpose_ssl_server(xp, x, ca);
434         if(!ret || ca) return ret;
435         /* We need to encipher or Netscape complains */
436         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
437         return ret;
438 }
439
440 /* common S/MIME checks */
441 static int purpose_smime(const X509 *x, int ca)
442 {
443         if(xku_reject(x,XKU_SMIME)) return 0;
444         if(ca) {
445                 int ca_ret;
446                 ca_ret = ca_check(x);
447                 if(!ca_ret) return 0;
448                 /* check nsCertType if present */
449                 if(x->ex_flags & EXFLAG_NSCERT) {
450                         if(x->ex_nscert & NS_SMIME_CA) return ca_ret;
451                         return 0;
452                 }
453                 if(ca_ret != 2) return ca_ret;
454                 else return 0;
455         }
456         if(x->ex_flags & EXFLAG_NSCERT) {
457                 if(x->ex_nscert & NS_SMIME) return 1;
458                 /* Workaround for some buggy certificates */
459                 if(x->ex_nscert & NS_SSL_CLIENT) return 2;
460                 return 0;
461         }
462         return 1;
463 }
464
465 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
466 {
467         int ret;
468         ret = purpose_smime(x, ca);
469         if(!ret || ca) return ret;
470         if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
471         return ret;
472 }
473
474 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
475 {
476         int ret;
477         ret = purpose_smime(x, ca);
478         if(!ret || ca) return ret;
479         if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
480         return ret;
481 }
482
483 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
484 {
485         if(ca) {
486                 int ca_ret;
487                 if((ca_ret = ca_check(x)) != 2) return ca_ret;
488                 else return 0;
489         }
490         if(ku_reject(x, KU_CRL_SIGN)) return 0;
491         return 1;
492 }
493
494 /* OCSP helper: this is *not* a full OCSP check. It just checks that
495  * each CA is valid. Additional checks must be made on the chain.
496  */
497
498 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
499 {
500         /* Must be a valid CA */
501         if(ca) {
502                 int ca_ret;
503                 ca_ret = ca_check(x);
504                 if(ca_ret != 2) return ca_ret;
505                 if(x->ex_flags & EXFLAG_NSCERT) {
506                         if(x->ex_nscert & NS_ANY_CA) return ca_ret;
507                         return 0;
508                 }
509                 return 0;
510         }
511         /* leaf certificate is checked in OCSP_verify() */
512         return 1;
513 }
514
515 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
516 {
517         return 1;
518 }
519
520 /* Various checks to see if one certificate issued the second.
521  * This can be used to prune a set of possible issuer certificates
522  * which have been looked up using some simple method such as by
523  * subject name.
524  * These are:
525  * 1. Check issuer_name(subject) == subject_name(issuer)
526  * 2. If akid(subject) exists check it matches issuer
527  * 3. If key_usage(issuer) exists check it supports certificate signing
528  * returns 0 for OK, positive for reason for mismatch, reasons match
529  * codes for X509_verify_cert()
530  */
531
532 int X509_check_issued(X509 *issuer, X509 *subject)
533 {
534         if(X509_NAME_cmp(X509_get_subject_name(issuer),
535                         X509_get_issuer_name(subject)))
536                                 return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
537         x509v3_cache_extensions(issuer);
538         x509v3_cache_extensions(subject);
539         if(subject->akid) {
540                 /* Check key ids (if present) */
541                 if(subject->akid->keyid && issuer->skid &&
542                  ASN1_OCTET_STRING_cmp(subject->akid->keyid, issuer->skid) )
543                                 return X509_V_ERR_AKID_SKID_MISMATCH;
544                 /* Check serial number */
545                 if(subject->akid->serial &&
546                         ASN1_INTEGER_cmp(X509_get_serialNumber(issuer),
547                                                 subject->akid->serial))
548                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
549                 /* Check issuer name */
550                 if(subject->akid->issuer) {
551                         /* Ugh, for some peculiar reason AKID includes
552                          * SEQUENCE OF GeneralName. So look for a DirName.
553                          * There may be more than one but we only take any
554                          * notice of the first.
555                          */
556                         GENERAL_NAMES *gens;
557                         GENERAL_NAME *gen;
558                         X509_NAME *nm = NULL;
559                         int i;
560                         gens = subject->akid->issuer;
561                         for(i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
562                                 gen = sk_GENERAL_NAME_value(gens, i);
563                                 if(gen->type == GEN_DIRNAME) {
564                                         nm = gen->d.dirn;
565                                         break;
566                                 }
567                         }
568                         if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
569                                 return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
570                 }
571         }
572         if(ku_reject(issuer, KU_KEY_CERT_SIGN)) return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
573         return X509_V_OK;
574 }
575