summaryrefslogtreecommitdiff
path: root/src/openvpn/ssl_verify_openssl.c
blob: e9692a09b659e45f7658cd0a497ba737112d9c68 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
/*
 *  OpenVPN -- An application to securely tunnel IP networks
 *             over a single TCP/UDP port, with support for SSL/TLS-based
 *             session authentication and key exchange,
 *             packet encryption, packet authentication, and
 *             packet compression.
 *
 *  Copyright (C) 2002-2017 OpenVPN Technologies, Inc. <sales@openvpn.net>
 *  Copyright (C) 2010-2017 Fox Crypto B.V. <openvpn@fox-it.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/**
 * @file Control Channel Verification Module OpenSSL implementation
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif

#include "syshead.h"

#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL)

#include "ssl_verify_openssl.h"

#include "error.h"
#include "ssl_openssl.h"
#include "ssl_verify.h"
#include "ssl_verify_backend.h"

#include <openssl/x509v3.h>
#include <openssl/err.h>

int
verify_callback(int preverify_ok, X509_STORE_CTX *ctx)
{
    int ret = 0;
    struct tls_session *session;
    SSL *ssl;
    struct gc_arena gc = gc_new();

    /* get the tls_session pointer */
    ssl = X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
    ASSERT(ssl);
    session = (struct tls_session *) SSL_get_ex_data(ssl, mydata_index);
    ASSERT(session);

    struct buffer cert_hash = x509_get_sha256_fingerprint(ctx->current_cert, &gc);
    cert_hash_remember(session, ctx->error_depth, &cert_hash);

    /* did peer present cert which was signed by our root cert? */
    if (!preverify_ok)
    {
        /* get the X509 name */
        char *subject = x509_get_subject(ctx->current_cert, &gc);

        if (!subject)
        {
            subject = "(Failed to retrieve certificate subject)";
        }

        /* Log and ignore missing CRL errors */
        if (ctx->error == X509_V_ERR_UNABLE_TO_GET_CRL)
        {
            msg(D_TLS_DEBUG_LOW, "VERIFY WARNING: depth=%d, %s: %s",
                ctx->error_depth,
                X509_verify_cert_error_string(ctx->error),
                subject);
            ret = 1;
            goto cleanup;
        }

        /* Remote site specified a certificate, but it's not correct */
        msg(D_TLS_ERRORS, "VERIFY ERROR: depth=%d, error=%s: %s",
            ctx->error_depth,
            X509_verify_cert_error_string(ctx->error),
            subject);

        ERR_clear_error();

        session->verified = false;
        goto cleanup;
    }

    if (SUCCESS != verify_cert(session, ctx->current_cert, ctx->error_depth))
    {
        goto cleanup;
    }

    ret = 1;

cleanup:
    gc_free(&gc);

    return ret;
}

#ifdef ENABLE_X509ALTUSERNAME
static
bool
extract_x509_extension(X509 *cert, char *fieldname, char *out, int size)
{
    bool retval = false;
    char *buf = 0;
    GENERAL_NAMES *extensions;
    int nid = OBJ_txt2nid(fieldname);

    extensions = (GENERAL_NAMES *)X509_get_ext_d2i(cert, nid, NULL, NULL);
    if (extensions)
    {
        int numalts;
        int i;
        /* get amount of alternatives,
         * RFC2459 claims there MUST be at least
         * one, but we don't depend on it...
         */

        numalts = sk_GENERAL_NAME_num(extensions);

        /* loop through all alternatives */
        for (i = 0; i<numalts; i++)
        {
            /* get a handle to alternative name number i */
            const GENERAL_NAME *name = sk_GENERAL_NAME_value(extensions, i );

            switch (name->type)
            {
                case GEN_EMAIL:
                    ASN1_STRING_to_UTF8((unsigned char **)&buf, name->d.ia5);
                    if (strlen(buf) != name->d.ia5->length)
                    {
                        msg(D_TLS_ERRORS, "ASN1 ERROR: string contained terminating zero");
                        OPENSSL_free(buf);
                    }
                    else
                    {
                        strncpynt(out, buf, size);
                        OPENSSL_free(buf);
                        retval = true;
                    }
                    break;

                default:
                    msg(D_TLS_DEBUG, "%s: ignoring general name field type %i",
                        __func__, name->type);
                    break;
            }
        }
        sk_GENERAL_NAME_free(extensions);
    }
    return retval;
}
#endif /* ENABLE_X509ALTUSERNAME */

/*
 * Extract a field from an X509 subject name.
 *
 * Example:
 *
 * /C=US/ST=CO/L=Denver/O=ORG/CN=First-CN/CN=Test-CA/Email=jim@yonan.net
 *
 * The common name is 'Test-CA'
 *
 * Return true on success, false on error (insufficient buffer size in 'out'
 * to contain result is grounds for error).
 */
static result_t
extract_x509_field_ssl(X509_NAME *x509, const char *field_name, char *out,
                       int size)
{
    int lastpos = -1;
    int tmp = -1;
    X509_NAME_ENTRY *x509ne = 0;
    ASN1_STRING *asn1 = 0;
    unsigned char *buf = NULL;
    int nid = OBJ_txt2nid(field_name);

    ASSERT(size > 0);
    *out = '\0';
    do {
        lastpos = tmp;
        tmp = X509_NAME_get_index_by_NID(x509, nid, lastpos);
    } while (tmp > -1);

    /* Nothing found */
    if (lastpos == -1)
    {
        return FAILURE;
    }

    x509ne = X509_NAME_get_entry(x509, lastpos);
    if (!x509ne)
    {
        return FAILURE;
    }

    asn1 = X509_NAME_ENTRY_get_data(x509ne);
    if (!asn1)
    {
        return FAILURE;
    }
    tmp = ASN1_STRING_to_UTF8(&buf, asn1);
    if (tmp <= 0)
    {
        return FAILURE;
    }

    strncpynt(out, (char *)buf, size);

    {
        const result_t ret = (strlen((char *)buf) < size) ? SUCCESS : FAILURE;
        OPENSSL_free(buf);
        return ret;
    }
}

result_t
backend_x509_get_username(char *common_name, int cn_len,
                          char *x509_username_field, X509 *peer_cert)
{
#ifdef ENABLE_X509ALTUSERNAME
    if (strncmp("ext:",x509_username_field,4) == 0)
    {
        if (!extract_x509_extension(peer_cert, x509_username_field+4, common_name, cn_len))
        {
            return FAILURE;
        }
    }
    else
#endif
    if (FAILURE == extract_x509_field_ssl(X509_get_subject_name(peer_cert),
                                          x509_username_field, common_name, cn_len))
    {
        return FAILURE;
    }

    return SUCCESS;
}

char *
backend_x509_get_serial(openvpn_x509_cert_t *cert, struct gc_arena *gc)
{
    ASN1_INTEGER *asn1_i;
    BIGNUM *bignum;
    char *openssl_serial, *serial;

    asn1_i = X509_get_serialNumber(cert);
    bignum = ASN1_INTEGER_to_BN(asn1_i, NULL);
    openssl_serial = BN_bn2dec(bignum);

    serial = string_alloc(openssl_serial, gc);

    BN_free(bignum);
    OPENSSL_free(openssl_serial);

    return serial;
}

char *
backend_x509_get_serial_hex(openvpn_x509_cert_t *cert, struct gc_arena *gc)
{
    const ASN1_INTEGER *asn1_i = X509_get_serialNumber(cert);

    return format_hex_ex(asn1_i->data, asn1_i->length, 0, 1, ":", gc);
}

struct buffer
x509_get_sha1_fingerprint(X509 *cert, struct gc_arena *gc)
{
    struct buffer hash = alloc_buf_gc(sizeof(cert->sha1_hash), gc);
    memcpy(BPTR(&hash), cert->sha1_hash, sizeof(cert->sha1_hash));
    ASSERT(buf_inc_len(&hash, sizeof(cert->sha1_hash)));
    return hash;
}

struct buffer
x509_get_sha256_fingerprint(X509 *cert, struct gc_arena *gc)
{
    struct buffer hash = alloc_buf_gc((EVP_sha256())->md_size, gc);
    X509_digest(cert, EVP_sha256(), BPTR(&hash), NULL);
    ASSERT(buf_inc_len(&hash, (EVP_sha256())->md_size));
    return hash;
}

char *
x509_get_subject(X509 *cert, struct gc_arena *gc)
{
    BIO *subject_bio = NULL;
    BUF_MEM *subject_mem;
    char *subject = NULL;
    int maxlen = 0;

    /*
     * Generate the subject string in OpenSSL proprietary format,
     * when in --compat-names mode
     */
    if (compat_flag(COMPAT_FLAG_QUERY | COMPAT_NAMES))
    {
        subject = gc_malloc(256, false, gc);
        X509_NAME_oneline(X509_get_subject_name(cert), subject, 256);
        subject[255] = '\0';
        return subject;
    }

    subject_bio = BIO_new(BIO_s_mem());
    if (subject_bio == NULL)
    {
        goto err;
    }

    X509_NAME_print_ex(subject_bio, X509_get_subject_name(cert),
                       0, XN_FLAG_SEP_CPLUS_SPC | XN_FLAG_FN_SN
                       |ASN1_STRFLGS_UTF8_CONVERT | ASN1_STRFLGS_ESC_CTRL);

    if (BIO_eof(subject_bio))
    {
        goto err;
    }

    BIO_get_mem_ptr(subject_bio, &subject_mem);

    maxlen = subject_mem->length + 1;
    subject = gc_malloc(maxlen, false, gc);

    memcpy(subject, subject_mem->data, maxlen);
    subject[maxlen - 1] = '\0';

err:
    if (subject_bio)
    {
        BIO_free(subject_bio);
    }

    return subject;
}


/*
 * x509-track implementation -- save X509 fields to environment,
 * using the naming convention:
 *
 *  X509_{cert_depth}_{name}={value}
 *
 * This function differs from x509_setenv below in the following ways:
 *
 * (1) Only explicitly named attributes in xt are saved, per usage
 *     of "x509-track" program options.
 * (2) Only the level 0 cert info is saved unless the XT_FULL_CHAIN
 *     flag is set in xt->flags (corresponds with prepending a '+'
 *     to the name when specified by "x509-track" program option).
 * (3) This function supports both X509 subject name fields as
 *     well as X509 V3 extensions.
 * (4) This function can return the SHA1 fingerprint of a cert, e.g.
 *       x509-track "+SHA1"
 *     will return the SHA1 fingerprint for each certificate in the
 *     peer chain.
 */

void
x509_track_add(const struct x509_track **ll_head, const char *name, int msglevel, struct gc_arena *gc)
{
    struct x509_track *xt;
    ALLOC_OBJ_CLEAR_GC(xt, struct x509_track, gc);
    if (*name == '+')
    {
        xt->flags |= XT_FULL_CHAIN;
        ++name;
    }
    xt->name = name;
    xt->nid = OBJ_txt2nid(name);
    if (xt->nid != NID_undef)
    {
        xt->next = *ll_head;
        *ll_head = xt;
    }
    else
    {
        msg(msglevel, "x509_track: no such attribute '%s'", name);
    }
}

/* worker method for setenv_x509_track */
static void
do_setenv_x509(struct env_set *es, const char *name, char *value, int depth)
{
    char *name_expand;
    size_t name_expand_size;

    string_mod(value, CC_ANY, CC_CRLF, '?');
    msg(D_X509_ATTR, "X509 ATTRIBUTE name='%s' value='%s' depth=%d", name, value, depth);
    name_expand_size = 64 + strlen(name);
    name_expand = (char *) malloc(name_expand_size);
    check_malloc_return(name_expand);
    openvpn_snprintf(name_expand, name_expand_size, "X509_%d_%s", depth, name);
    setenv_str(es, name_expand, value);
    free(name_expand);
}

void
x509_setenv_track(const struct x509_track *xt, struct env_set *es, const int depth, X509 *x509)
{
    struct gc_arena gc = gc_new();
    X509_NAME *x509_name = X509_get_subject_name(x509);
    const char nullc = '\0';

    while (xt)
    {
        if (depth == 0 || (xt->flags & XT_FULL_CHAIN))
        {
            switch (xt->nid)
            {
                case NID_sha1:
                case NID_sha256:
                {
                    struct buffer fp_buf;
                    char *fp_str = NULL;

                    if (xt->nid == NID_sha1)
                    {
                        fp_buf = x509_get_sha1_fingerprint(x509, &gc);
                    }
                    else
                    {
                        fp_buf = x509_get_sha256_fingerprint(x509, &gc);
                    }

                    fp_str = format_hex_ex(BPTR(&fp_buf), BLEN(&fp_buf), 0,
                                           1 | FHE_CAPS, ":", &gc);
                    do_setenv_x509(es, xt->name, fp_str, depth);
                }
                break;

                default:
                {
                    int i = X509_NAME_get_index_by_NID(x509_name, xt->nid, -1);
                    if (i >= 0)
                    {
                        X509_NAME_ENTRY *ent = X509_NAME_get_entry(x509_name, i);
                        if (ent)
                        {
                            ASN1_STRING *val = X509_NAME_ENTRY_get_data(ent);
                            unsigned char *buf;
                            buf = (unsigned char *)1; /* bug in OpenSSL 0.9.6b ASN1_STRING_to_UTF8 requires this workaround */
                            if (ASN1_STRING_to_UTF8(&buf, val) > 0)
                            {
                                do_setenv_x509(es, xt->name, (char *)buf, depth);
                                OPENSSL_free(buf);
                            }
                        }
                    }
                    else
                    {
                        i = X509_get_ext_by_NID(x509, xt->nid, -1);
                        if (i >= 0)
                        {
                            X509_EXTENSION *ext = X509_get_ext(x509, i);
                            if (ext)
                            {
                                BIO *bio = BIO_new(BIO_s_mem());
                                if (bio)
                                {
                                    if (X509V3_EXT_print(bio, ext, 0, 0))
                                    {
                                        if (BIO_write(bio, &nullc, 1) == 1)
                                        {
                                            char *str;
                                            BIO_get_mem_data(bio, &str);
                                            do_setenv_x509(es, xt->name, str, depth);
                                        }
                                    }
                                    BIO_free(bio);
                                }
                            }
                        }
                    }
                }
            }
        }
        xt = xt->next;
    }
    gc_free(&gc);
}

/*
 * Save X509 fields to environment, using the naming convention:
 *
 *  X509_{cert_depth}_{name}={value}
 */
void
x509_setenv(struct env_set *es, int cert_depth, openvpn_x509_cert_t *peer_cert)
{
    int i, n;
    int fn_nid;
    ASN1_OBJECT *fn;
    ASN1_STRING *val;
    X509_NAME_ENTRY *ent;
    const char *objbuf;
    unsigned char *buf;
    char *name_expand;
    size_t name_expand_size;
    X509_NAME *x509 = X509_get_subject_name(peer_cert);

    n = X509_NAME_entry_count(x509);
    for (i = 0; i < n; ++i)
    {
        ent = X509_NAME_get_entry(x509, i);
        if (!ent)
        {
            continue;
        }
        fn = X509_NAME_ENTRY_get_object(ent);
        if (!fn)
        {
            continue;
        }
        val = X509_NAME_ENTRY_get_data(ent);
        if (!val)
        {
            continue;
        }
        fn_nid = OBJ_obj2nid(fn);
        if (fn_nid == NID_undef)
        {
            continue;
        }
        objbuf = OBJ_nid2sn(fn_nid);
        if (!objbuf)
        {
            continue;
        }
        buf = (unsigned char *)1; /* bug in OpenSSL 0.9.6b ASN1_STRING_to_UTF8 requires this workaround */
        if (ASN1_STRING_to_UTF8(&buf, val) <= 0)
        {
            continue;
        }
        name_expand_size = 64 + strlen(objbuf);
        name_expand = (char *) malloc(name_expand_size);
        check_malloc_return(name_expand);
        openvpn_snprintf(name_expand, name_expand_size, "X509_%d_%s", cert_depth,
                         objbuf);
        string_mod(name_expand, CC_PRINT, CC_CRLF, '_');
        string_mod((char *)buf, CC_PRINT, CC_CRLF, '_');
        setenv_str_incr(es, name_expand, (char *)buf);
        free(name_expand);
        OPENSSL_free(buf);
    }
}

result_t
x509_verify_ns_cert_type(const openvpn_x509_cert_t *peer_cert, const int usage)
{
    if (usage == NS_CERT_CHECK_NONE)
    {
        return SUCCESS;
    }
    if (usage == NS_CERT_CHECK_CLIENT)
    {
        return ((peer_cert->ex_flags & EXFLAG_NSCERT)
                && (peer_cert->ex_nscert & NS_SSL_CLIENT)) ? SUCCESS : FAILURE;
    }
    if (usage == NS_CERT_CHECK_SERVER)
    {
        return ((peer_cert->ex_flags & EXFLAG_NSCERT)
                && (peer_cert->ex_nscert & NS_SSL_SERVER))  ? SUCCESS : FAILURE;
    }

    return FAILURE;
}

result_t
x509_verify_cert_ku(X509 *x509, const unsigned *const expected_ku,
                    int expected_len)
{
    ASN1_BIT_STRING *ku = NULL;
    result_t fFound = FAILURE;

    if ((ku = (ASN1_BIT_STRING *) X509_get_ext_d2i(x509, NID_key_usage, NULL,
                                                   NULL)) == NULL)
    {
        msg(D_HANDSHAKE, "Certificate does not have key usage extension");
    }
    else
    {
        unsigned nku = 0;
        int i;
        for (i = 0; i < 8; i++)
        {
            if (ASN1_BIT_STRING_get_bit(ku, i))
            {
                nku |= 1 << (7 - i);
            }
        }

        /*
         * Fixup if no LSB bits
         */
        if ((nku & 0xff) == 0)
        {
            nku >>= 8;
        }

        msg(D_HANDSHAKE, "Validating certificate key usage");
        for (i = 0; fFound != SUCCESS && i < expected_len; i++)
        {
            if (expected_ku[i] != 0)
            {
                msg(D_HANDSHAKE, "++ Certificate has key usage  %04x, expects "
                    "%04x", nku, expected_ku[i]);

                if (nku == expected_ku[i])
                {
                    fFound = SUCCESS;
                }
            }
        }
    }

    if (ku != NULL)
    {
        ASN1_BIT_STRING_free(ku);
    }

    return fFound;
}

result_t
x509_verify_cert_eku(X509 *x509, const char *const expected_oid)
{
    EXTENDED_KEY_USAGE *eku = NULL;
    result_t fFound = FAILURE;

    if ((eku = (EXTENDED_KEY_USAGE *) X509_get_ext_d2i(x509, NID_ext_key_usage,
                                                       NULL, NULL)) == NULL)
    {
        msg(D_HANDSHAKE, "Certificate does not have extended key usage extension");
    }
    else
    {
        int i;

        msg(D_HANDSHAKE, "Validating certificate extended key usage");
        for (i = 0; SUCCESS != fFound && i < sk_ASN1_OBJECT_num(eku); i++)
        {
            ASN1_OBJECT *oid = sk_ASN1_OBJECT_value(eku, i);
            char szOid[1024];

            if (SUCCESS != fFound && OBJ_obj2txt(szOid, sizeof(szOid), oid, 0) != -1)
            {
                msg(D_HANDSHAKE, "++ Certificate has EKU (str) %s, expects %s",
                    szOid, expected_oid);
                if (!strcmp(expected_oid, szOid))
                {
                    fFound = SUCCESS;
                }
            }
            if (SUCCESS != fFound && OBJ_obj2txt(szOid, sizeof(szOid), oid, 1) != -1)
            {
                msg(D_HANDSHAKE, "++ Certificate has EKU (oid) %s, expects %s",
                    szOid, expected_oid);
                if (!strcmp(expected_oid, szOid))
                {
                    fFound = SUCCESS;
                }
            }
        }
    }

    if (eku != NULL)
    {
        sk_ASN1_OBJECT_pop_free(eku, ASN1_OBJECT_free);
    }

    return fFound;
}

result_t
x509_write_pem(FILE *peercert_file, X509 *peercert)
{
    if (PEM_write_X509(peercert_file, peercert) < 0)
    {
        msg(M_ERR, "Failed to write peer certificate in PEM format");
        return FAILURE;
    }
    return SUCCESS;
}

bool
tls_verify_crl_missing(const struct tls_options *opt)
{
    if (!opt->crl_file || (opt->ssl_flags & SSLF_CRL_VERIFY_DIR))
    {
        return false;
    }

    X509_STORE *store = SSL_CTX_get_cert_store(opt->ssl_ctx.ctx);
    if (!store)
    {
        crypto_msg(M_FATAL, "Cannot get certificate store");
    }

    for (int i = 0; i < sk_X509_OBJECT_num(store->objs); i++)
    {
        X509_OBJECT *obj = sk_X509_OBJECT_value(store->objs, i);
        ASSERT(obj);
        if (obj->type == X509_LU_CRL)
        {
            return false;
        }
    }
    return true;
}

#endif /* defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL) */