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      1 /* v3_purp.c */
      2 /* Written by Dr Stephen N Henson (steve (at) openssl.org) for the OpenSSL
      3  * project 2001.
      4  */
      5 /* ====================================================================
      6  * Copyright (c) 1999-2004 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 (at) 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 (at) cryptsoft.com).  This product includes software written by Tim
     55  * Hudson (tjh (at) 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 check_ssl_ca(const X509 *x);
     67 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca);
     68 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
     69 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca);
     70 static int purpose_smime(const X509 *x, int ca);
     71 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
     72 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca);
     73 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca);
     74 static int check_purpose_timestamp_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 	{X509_PURPOSE_TIMESTAMP_SIGN, X509_TRUST_TSA, 0, check_purpose_timestamp_sign, "Time Stamp signing", "timestampsign", NULL},
     92 };
     93 
     94 #define X509_PURPOSE_COUNT (sizeof(xstandard)/sizeof(X509_PURPOSE))
     95 
     96 IMPLEMENT_STACK_OF(X509_PURPOSE)
     97 
     98 static STACK_OF(X509_PURPOSE) *xptable = NULL;
     99 
    100 static int xp_cmp(const X509_PURPOSE * const *a,
    101 		const X509_PURPOSE * const *b)
    102 {
    103 	return (*a)->purpose - (*b)->purpose;
    104 }
    105 
    106 /* As much as I'd like to make X509_check_purpose use a "const" X509*
    107  * I really can't because it does recalculate hashes and do other non-const
    108  * things. */
    109 int X509_check_purpose(X509 *x, int id, int ca)
    110 {
    111 	int idx;
    112 	const X509_PURPOSE *pt;
    113 	if(!(x->ex_flags & EXFLAG_SET)) {
    114 		CRYPTO_w_lock(CRYPTO_LOCK_X509);
    115 		x509v3_cache_extensions(x);
    116 		CRYPTO_w_unlock(CRYPTO_LOCK_X509);
    117 	}
    118 	if(id == -1) return 1;
    119 	idx = X509_PURPOSE_get_by_id(id);
    120 	if(idx == -1) return -1;
    121 	pt = X509_PURPOSE_get0(idx);
    122 	return pt->check_purpose(pt, x, ca);
    123 }
    124 
    125 int X509_PURPOSE_set(int *p, int purpose)
    126 {
    127 	if(X509_PURPOSE_get_by_id(purpose) == -1) {
    128 		X509V3err(X509V3_F_X509_PURPOSE_SET, X509V3_R_INVALID_PURPOSE);
    129 		return 0;
    130 	}
    131 	*p = purpose;
    132 	return 1;
    133 }
    134 
    135 int X509_PURPOSE_get_count(void)
    136 {
    137 	if(!xptable) return X509_PURPOSE_COUNT;
    138 	return sk_X509_PURPOSE_num(xptable) + X509_PURPOSE_COUNT;
    139 }
    140 
    141 X509_PURPOSE * X509_PURPOSE_get0(int idx)
    142 {
    143 	if(idx < 0) return NULL;
    144 	if(idx < (int)X509_PURPOSE_COUNT) return xstandard + idx;
    145 	return sk_X509_PURPOSE_value(xptable, idx - X509_PURPOSE_COUNT);
    146 }
    147 
    148 int X509_PURPOSE_get_by_sname(char *sname)
    149 {
    150 	int i;
    151 	X509_PURPOSE *xptmp;
    152 	for(i = 0; i < X509_PURPOSE_get_count(); i++) {
    153 		xptmp = X509_PURPOSE_get0(i);
    154 		if(!strcmp(xptmp->sname, sname)) return i;
    155 	}
    156 	return -1;
    157 }
    158 
    159 int X509_PURPOSE_get_by_id(int purpose)
    160 {
    161 	X509_PURPOSE tmp;
    162 	int idx;
    163 	if((purpose >= X509_PURPOSE_MIN) && (purpose <= X509_PURPOSE_MAX))
    164 		return purpose - X509_PURPOSE_MIN;
    165 	tmp.purpose = purpose;
    166 	if(!xptable) return -1;
    167 	idx = sk_X509_PURPOSE_find(xptable, &tmp);
    168 	if(idx == -1) return -1;
    169 	return idx + X509_PURPOSE_COUNT;
    170 }
    171 
    172 int X509_PURPOSE_add(int id, int trust, int flags,
    173 			int (*ck)(const X509_PURPOSE *, const X509 *, int),
    174 					char *name, char *sname, void *arg)
    175 {
    176 	int idx;
    177 	X509_PURPOSE *ptmp;
    178 	/* This is set according to what we change: application can't set it */
    179 	flags &= ~X509_PURPOSE_DYNAMIC;
    180 	/* This will always be set for application modified trust entries */
    181 	flags |= X509_PURPOSE_DYNAMIC_NAME;
    182 	/* Get existing entry if any */
    183 	idx = X509_PURPOSE_get_by_id(id);
    184 	/* Need a new entry */
    185 	if(idx == -1) {
    186 		if(!(ptmp = OPENSSL_malloc(sizeof(X509_PURPOSE)))) {
    187 			X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
    188 			return 0;
    189 		}
    190 		ptmp->flags = X509_PURPOSE_DYNAMIC;
    191 	} else ptmp = X509_PURPOSE_get0(idx);
    192 
    193 	/* OPENSSL_free existing name if dynamic */
    194 	if(ptmp->flags & X509_PURPOSE_DYNAMIC_NAME) {
    195 		OPENSSL_free(ptmp->name);
    196 		OPENSSL_free(ptmp->sname);
    197 	}
    198 	/* dup supplied name */
    199 	ptmp->name = BUF_strdup(name);
    200 	ptmp->sname = BUF_strdup(sname);
    201 	if(!ptmp->name || !ptmp->sname) {
    202 		X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
    203 		return 0;
    204 	}
    205 	/* Keep the dynamic flag of existing entry */
    206 	ptmp->flags &= X509_PURPOSE_DYNAMIC;
    207 	/* Set all other flags */
    208 	ptmp->flags |= flags;
    209 
    210 	ptmp->purpose = id;
    211 	ptmp->trust = trust;
    212 	ptmp->check_purpose = ck;
    213 	ptmp->usr_data = arg;
    214 
    215 	/* If its a new entry manage the dynamic table */
    216 	if(idx == -1) {
    217 		if(!xptable && !(xptable = sk_X509_PURPOSE_new(xp_cmp))) {
    218 			X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
    219 			return 0;
    220 		}
    221 		if (!sk_X509_PURPOSE_push(xptable, ptmp)) {
    222 			X509V3err(X509V3_F_X509_PURPOSE_ADD,ERR_R_MALLOC_FAILURE);
    223 			return 0;
    224 		}
    225 	}
    226 	return 1;
    227 }
    228 
    229 static void xptable_free(X509_PURPOSE *p)
    230 	{
    231 	if(!p) return;
    232 	if (p->flags & X509_PURPOSE_DYNAMIC)
    233 		{
    234 		if (p->flags & X509_PURPOSE_DYNAMIC_NAME) {
    235 			OPENSSL_free(p->name);
    236 			OPENSSL_free(p->sname);
    237 		}
    238 		OPENSSL_free(p);
    239 		}
    240 	}
    241 
    242 void X509_PURPOSE_cleanup(void)
    243 {
    244 	unsigned int i;
    245 	sk_X509_PURPOSE_pop_free(xptable, xptable_free);
    246 	for(i = 0; i < X509_PURPOSE_COUNT; i++) xptable_free(xstandard + i);
    247 	xptable = NULL;
    248 }
    249 
    250 int X509_PURPOSE_get_id(X509_PURPOSE *xp)
    251 {
    252 	return xp->purpose;
    253 }
    254 
    255 char *X509_PURPOSE_get0_name(X509_PURPOSE *xp)
    256 {
    257 	return xp->name;
    258 }
    259 
    260 char *X509_PURPOSE_get0_sname(X509_PURPOSE *xp)
    261 {
    262 	return xp->sname;
    263 }
    264 
    265 int X509_PURPOSE_get_trust(X509_PURPOSE *xp)
    266 {
    267 	return xp->trust;
    268 }
    269 
    270 static int nid_cmp(const int *a, const int *b)
    271 	{
    272 	return *a - *b;
    273 	}
    274 
    275 DECLARE_OBJ_BSEARCH_CMP_FN(int, int, nid);
    276 IMPLEMENT_OBJ_BSEARCH_CMP_FN(int, int, nid);
    277 
    278 int X509_supported_extension(X509_EXTENSION *ex)
    279 	{
    280 	/* This table is a list of the NIDs of supported extensions:
    281 	 * that is those which are used by the verify process. If
    282 	 * an extension is critical and doesn't appear in this list
    283 	 * then the verify process will normally reject the certificate.
    284 	 * The list must be kept in numerical order because it will be
    285 	 * searched using bsearch.
    286 	 */
    287 
    288 	static const int supported_nids[] = {
    289 		NID_netscape_cert_type, /* 71 */
    290         	NID_key_usage,		/* 83 */
    291 		NID_subject_alt_name,	/* 85 */
    292 		NID_basic_constraints,	/* 87 */
    293 		NID_certificate_policies, /* 89 */
    294         	NID_ext_key_usage,	/* 126 */
    295 #ifndef OPENSSL_NO_RFC3779
    296 		NID_sbgp_ipAddrBlock,	/* 290 */
    297 		NID_sbgp_autonomousSysNum, /* 291 */
    298 #endif
    299 		NID_policy_constraints,	/* 401 */
    300 		NID_proxyCertInfo,	/* 663 */
    301 		NID_name_constraints,	/* 666 */
    302 		NID_policy_mappings,	/* 747 */
    303 		NID_inhibit_any_policy	/* 748 */
    304 	};
    305 
    306 	int ex_nid = OBJ_obj2nid(X509_EXTENSION_get_object(ex));
    307 
    308 	if (ex_nid == NID_undef)
    309 		return 0;
    310 
    311 	if (OBJ_bsearch_nid(&ex_nid, supported_nids,
    312 			sizeof(supported_nids)/sizeof(int)))
    313 		return 1;
    314 	return 0;
    315 	}
    316 
    317 static void setup_dp(X509 *x, DIST_POINT *dp)
    318 	{
    319 	X509_NAME *iname = NULL;
    320 	int i;
    321 	if (dp->reasons)
    322 		{
    323 		if (dp->reasons->length > 0)
    324 			dp->dp_reasons = dp->reasons->data[0];
    325 		if (dp->reasons->length > 1)
    326 			dp->dp_reasons |= (dp->reasons->data[1] << 8);
    327 		dp->dp_reasons &= CRLDP_ALL_REASONS;
    328 		}
    329 	else
    330 		dp->dp_reasons = CRLDP_ALL_REASONS;
    331 	if (!dp->distpoint || (dp->distpoint->type != 1))
    332 		return;
    333 	for (i = 0; i < sk_GENERAL_NAME_num(dp->CRLissuer); i++)
    334 		{
    335 		GENERAL_NAME *gen = sk_GENERAL_NAME_value(dp->CRLissuer, i);
    336 		if (gen->type == GEN_DIRNAME)
    337 			{
    338 			iname = gen->d.directoryName;
    339 			break;
    340 			}
    341 		}
    342 	if (!iname)
    343 		iname = X509_get_issuer_name(x);
    344 
    345 	DIST_POINT_set_dpname(dp->distpoint, iname);
    346 
    347 	}
    348 
    349 static void setup_crldp(X509 *x)
    350 	{
    351 	int i;
    352 	x->crldp = X509_get_ext_d2i(x, NID_crl_distribution_points, NULL, NULL);
    353 	for (i = 0; i < sk_DIST_POINT_num(x->crldp); i++)
    354 		setup_dp(x, sk_DIST_POINT_value(x->crldp, i));
    355 	}
    356 
    357 static void x509v3_cache_extensions(X509 *x)
    358 {
    359 	BASIC_CONSTRAINTS *bs;
    360 	PROXY_CERT_INFO_EXTENSION *pci;
    361 	ASN1_BIT_STRING *usage;
    362 	ASN1_BIT_STRING *ns;
    363 	EXTENDED_KEY_USAGE *extusage;
    364 	X509_EXTENSION *ex;
    365 
    366 	int i;
    367 	if(x->ex_flags & EXFLAG_SET) return;
    368 #ifndef OPENSSL_NO_SHA
    369 	X509_digest(x, EVP_sha1(), x->sha1_hash, NULL);
    370 #endif
    371 	/* Does subject name match issuer ? */
    372 	if(!X509_NAME_cmp(X509_get_subject_name(x), X509_get_issuer_name(x)))
    373 			 x->ex_flags |= EXFLAG_SI;
    374 	/* V1 should mean no extensions ... */
    375 	if(!X509_get_version(x)) x->ex_flags |= EXFLAG_V1;
    376 	/* Handle basic constraints */
    377 	if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
    378 		if(bs->ca) x->ex_flags |= EXFLAG_CA;
    379 		if(bs->pathlen) {
    380 			if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
    381 						|| !bs->ca) {
    382 				x->ex_flags |= EXFLAG_INVALID;
    383 				x->ex_pathlen = 0;
    384 			} else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
    385 		} else x->ex_pathlen = -1;
    386 		BASIC_CONSTRAINTS_free(bs);
    387 		x->ex_flags |= EXFLAG_BCONS;
    388 	}
    389 	/* Handle proxy certificates */
    390 	if((pci=X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
    391 		if (x->ex_flags & EXFLAG_CA
    392 		    || X509_get_ext_by_NID(x, NID_subject_alt_name, 0) >= 0
    393 		    || X509_get_ext_by_NID(x, NID_issuer_alt_name, 0) >= 0) {
    394 			x->ex_flags |= EXFLAG_INVALID;
    395 		}
    396 		if (pci->pcPathLengthConstraint) {
    397 			x->ex_pcpathlen =
    398 				ASN1_INTEGER_get(pci->pcPathLengthConstraint);
    399 		} else x->ex_pcpathlen = -1;
    400 		PROXY_CERT_INFO_EXTENSION_free(pci);
    401 		x->ex_flags |= EXFLAG_PROXY;
    402 	}
    403 	/* Handle key usage */
    404 	if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
    405 		if(usage->length > 0) {
    406 			x->ex_kusage = usage->data[0];
    407 			if(usage->length > 1)
    408 				x->ex_kusage |= usage->data[1] << 8;
    409 		} else x->ex_kusage = 0;
    410 		x->ex_flags |= EXFLAG_KUSAGE;
    411 		ASN1_BIT_STRING_free(usage);
    412 	}
    413 	x->ex_xkusage = 0;
    414 	if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
    415 		x->ex_flags |= EXFLAG_XKUSAGE;
    416 		for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
    417 			switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
    418 				case NID_server_auth:
    419 				x->ex_xkusage |= XKU_SSL_SERVER;
    420 				break;
    421 
    422 				case NID_client_auth:
    423 				x->ex_xkusage |= XKU_SSL_CLIENT;
    424 				break;
    425 
    426 				case NID_email_protect:
    427 				x->ex_xkusage |= XKU_SMIME;
    428 				break;
    429 
    430 				case NID_code_sign:
    431 				x->ex_xkusage |= XKU_CODE_SIGN;
    432 				break;
    433 
    434 				case NID_ms_sgc:
    435 				case NID_ns_sgc:
    436 				x->ex_xkusage |= XKU_SGC;
    437 				break;
    438 
    439 				case NID_OCSP_sign:
    440 				x->ex_xkusage |= XKU_OCSP_SIGN;
    441 				break;
    442 
    443 				case NID_time_stamp:
    444 				x->ex_xkusage |= XKU_TIMESTAMP;
    445 				break;
    446 
    447 				case NID_dvcs:
    448 				x->ex_xkusage |= XKU_DVCS;
    449 				break;
    450 			}
    451 		}
    452 		sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
    453 	}
    454 
    455 	if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
    456 		if(ns->length > 0) x->ex_nscert = ns->data[0];
    457 		else x->ex_nscert = 0;
    458 		x->ex_flags |= EXFLAG_NSCERT;
    459 		ASN1_BIT_STRING_free(ns);
    460 	}
    461 	x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
    462 	x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
    463 	x->altname = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
    464 	x->nc = X509_get_ext_d2i(x, NID_name_constraints, &i, NULL);
    465 	if (!x->nc && (i != -1))
    466 		x->ex_flags |= EXFLAG_INVALID;
    467 	setup_crldp(x);
    468 
    469 #ifndef OPENSSL_NO_RFC3779
    470  	x->rfc3779_addr =X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
    471  	x->rfc3779_asid =X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
    472  					  NULL, NULL);
    473 #endif
    474 	for (i = 0; i < X509_get_ext_count(x); i++)
    475 		{
    476 		ex = X509_get_ext(x, i);
    477 		if (OBJ_obj2nid(X509_EXTENSION_get_object(ex))
    478 					== NID_freshest_crl)
    479 			x->ex_flags |= EXFLAG_FRESHEST;
    480 		if (!X509_EXTENSION_get_critical(ex))
    481 			continue;
    482 		if (!X509_supported_extension(ex))
    483 			{
    484 			x->ex_flags |= EXFLAG_CRITICAL;
    485 			break;
    486 			}
    487 		}
    488 	x->ex_flags |= EXFLAG_SET;
    489 }
    490 
    491 /* CA checks common to all purposes
    492  * return codes:
    493  * 0 not a CA
    494  * 1 is a CA
    495  * 2 basicConstraints absent so "maybe" a CA
    496  * 3 basicConstraints absent but self signed V1.
    497  * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
    498  */
    499 
    500 #define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
    501 #define ku_reject(x, usage) \
    502 	(((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
    503 #define xku_reject(x, usage) \
    504 	(((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
    505 #define ns_reject(x, usage) \
    506 	(((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))
    507 
    508 static int check_ca(const X509 *x)
    509 {
    510 	/* keyUsage if present should allow cert signing */
    511 	if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
    512 	if(x->ex_flags & EXFLAG_BCONS) {
    513 		if(x->ex_flags & EXFLAG_CA) return 1;
    514 		/* If basicConstraints says not a CA then say so */
    515 		else return 0;
    516 	} else {
    517 		/* we support V1 roots for...  uh, I don't really know why. */
    518 		if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
    519 		/* If key usage present it must have certSign so tolerate it */
    520 		else if (x->ex_flags & EXFLAG_KUSAGE) return 4;
    521 		/* Older certificates could have Netscape-specific CA types */
    522 		else if (x->ex_flags & EXFLAG_NSCERT
    523 			 && x->ex_nscert & NS_ANY_CA) return 5;
    524 		/* can this still be regarded a CA certificate?  I doubt it */
    525 		return 0;
    526 	}
    527 }
    528 
    529 int X509_check_ca(X509 *x)
    530 {
    531 	if(!(x->ex_flags & EXFLAG_SET)) {
    532 		CRYPTO_w_lock(CRYPTO_LOCK_X509);
    533 		x509v3_cache_extensions(x);
    534 		CRYPTO_w_unlock(CRYPTO_LOCK_X509);
    535 	}
    536 
    537 	return check_ca(x);
    538 }
    539 
    540 /* Check SSL CA: common checks for SSL client and server */
    541 static int check_ssl_ca(const X509 *x)
    542 {
    543 	int ca_ret;
    544 	ca_ret = check_ca(x);
    545 	if(!ca_ret) return 0;
    546 	/* check nsCertType if present */
    547 	if(ca_ret != 5 || x->ex_nscert & NS_SSL_CA) return ca_ret;
    548 	else return 0;
    549 }
    550 
    551 
    552 static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
    553 {
    554 	if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
    555 	if(ca) return check_ssl_ca(x);
    556 	/* We need to do digital signatures with it */
    557 	if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
    558 	/* nsCertType if present should allow SSL client use */
    559 	if(ns_reject(x, NS_SSL_CLIENT)) return 0;
    560 	return 1;
    561 }
    562 
    563 static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
    564 {
    565 	if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
    566 	if(ca) return check_ssl_ca(x);
    567 
    568 	if(ns_reject(x, NS_SSL_SERVER)) return 0;
    569 	/* Now as for keyUsage: we'll at least need to sign OR encipher */
    570 	if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
    571 
    572 	return 1;
    573 
    574 }
    575 
    576 static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
    577 {
    578 	int ret;
    579 	ret = check_purpose_ssl_server(xp, x, ca);
    580 	if(!ret || ca) return ret;
    581 	/* We need to encipher or Netscape complains */
    582 	if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
    583 	return ret;
    584 }
    585 
    586 /* common S/MIME checks */
    587 static int purpose_smime(const X509 *x, int ca)
    588 {
    589 	if(xku_reject(x,XKU_SMIME)) return 0;
    590 	if(ca) {
    591 		int ca_ret;
    592 		ca_ret = check_ca(x);
    593 		if(!ca_ret) return 0;
    594 		/* check nsCertType if present */
    595 		if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
    596 		else return 0;
    597 	}
    598 	if(x->ex_flags & EXFLAG_NSCERT) {
    599 		if(x->ex_nscert & NS_SMIME) return 1;
    600 		/* Workaround for some buggy certificates */
    601 		if(x->ex_nscert & NS_SSL_CLIENT) return 2;
    602 		return 0;
    603 	}
    604 	return 1;
    605 }
    606 
    607 static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
    608 {
    609 	int ret;
    610 	ret = purpose_smime(x, ca);
    611 	if(!ret || ca) return ret;
    612 	if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
    613 	return ret;
    614 }
    615 
    616 static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
    617 {
    618 	int ret;
    619 	ret = purpose_smime(x, ca);
    620 	if(!ret || ca) return ret;
    621 	if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
    622 	return ret;
    623 }
    624 
    625 static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
    626 {
    627 	if(ca) {
    628 		int ca_ret;
    629 		if((ca_ret = check_ca(x)) != 2) return ca_ret;
    630 		else return 0;
    631 	}
    632 	if(ku_reject(x, KU_CRL_SIGN)) return 0;
    633 	return 1;
    634 }
    635 
    636 /* OCSP helper: this is *not* a full OCSP check. It just checks that
    637  * each CA is valid. Additional checks must be made on the chain.
    638  */
    639 
    640 static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
    641 {
    642 	/* Must be a valid CA.  Should we really support the "I don't know"
    643 	   value (2)? */
    644 	if(ca) return check_ca(x);
    645 	/* leaf certificate is checked in OCSP_verify() */
    646 	return 1;
    647 }
    648 
    649 static int check_purpose_timestamp_sign(const X509_PURPOSE *xp, const X509 *x,
    650 					int ca)
    651 {
    652 	int i_ext;
    653 
    654 	/* If ca is true we must return if this is a valid CA certificate. */
    655 	if (ca) return check_ca(x);
    656 
    657 	/*
    658 	 * Check the optional key usage field:
    659 	 * if Key Usage is present, it must be one of digitalSignature
    660 	 * and/or nonRepudiation (other values are not consistent and shall
    661 	 * be rejected).
    662 	 */
    663 	if ((x->ex_flags & EXFLAG_KUSAGE)
    664 	    && ((x->ex_kusage & ~(KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE)) ||
    665 		!(x->ex_kusage & (KU_NON_REPUDIATION | KU_DIGITAL_SIGNATURE))))
    666 		return 0;
    667 
    668 	/* Only time stamp key usage is permitted and it's required. */
    669 	if (!(x->ex_flags & EXFLAG_XKUSAGE) || x->ex_xkusage != XKU_TIMESTAMP)
    670 		return 0;
    671 
    672 	/* Extended Key Usage MUST be critical */
    673 	i_ext = X509_get_ext_by_NID((X509 *) x, NID_ext_key_usage, 0);
    674 	if (i_ext >= 0)
    675 		{
    676 		X509_EXTENSION *ext = X509_get_ext((X509 *) x, i_ext);
    677 		if (!X509_EXTENSION_get_critical(ext))
    678 			return 0;
    679 		}
    680 
    681 	return 1;
    682 }
    683 
    684 static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
    685 {
    686 	return 1;
    687 }
    688 
    689 /* Various checks to see if one certificate issued the second.
    690  * This can be used to prune a set of possible issuer certificates
    691  * which have been looked up using some simple method such as by
    692  * subject name.
    693  * These are:
    694  * 1. Check issuer_name(subject) == subject_name(issuer)
    695  * 2. If akid(subject) exists check it matches issuer
    696  * 3. If key_usage(issuer) exists check it supports certificate signing
    697  * returns 0 for OK, positive for reason for mismatch, reasons match
    698  * codes for X509_verify_cert()
    699  */
    700 
    701 int X509_check_issued(X509 *issuer, X509 *subject)
    702 {
    703 	if(X509_NAME_cmp(X509_get_subject_name(issuer),
    704 			X509_get_issuer_name(subject)))
    705 				return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
    706 	x509v3_cache_extensions(issuer);
    707 	x509v3_cache_extensions(subject);
    708 
    709 	if(subject->akid)
    710 		{
    711 		int ret = X509_check_akid(issuer, subject->akid);
    712 		if (ret != X509_V_OK)
    713 			return ret;
    714 		}
    715 
    716 	if(subject->ex_flags & EXFLAG_PROXY)
    717 		{
    718 		if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
    719 			return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
    720 		}
    721 	else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
    722 		return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
    723 	return X509_V_OK;
    724 }
    725 
    726 int X509_check_akid(X509 *issuer, AUTHORITY_KEYID *akid)
    727 	{
    728 
    729 	if(!akid)
    730 		return X509_V_OK;
    731 
    732 	/* Check key ids (if present) */
    733 	if(akid->keyid && issuer->skid &&
    734 		 ASN1_OCTET_STRING_cmp(akid->keyid, issuer->skid) )
    735 				return X509_V_ERR_AKID_SKID_MISMATCH;
    736 	/* Check serial number */
    737 	if(akid->serial &&
    738 		ASN1_INTEGER_cmp(X509_get_serialNumber(issuer), akid->serial))
    739 				return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
    740 	/* Check issuer name */
    741 	if(akid->issuer)
    742 		{
    743 		/* Ugh, for some peculiar reason AKID includes
    744 		 * SEQUENCE OF GeneralName. So look for a DirName.
    745 		 * There may be more than one but we only take any
    746 		 * notice of the first.
    747 		 */
    748 		GENERAL_NAMES *gens;
    749 		GENERAL_NAME *gen;
    750 		X509_NAME *nm = NULL;
    751 		int i;
    752 		gens = akid->issuer;
    753 		for(i = 0; i < sk_GENERAL_NAME_num(gens); i++)
    754 			{
    755 			gen = sk_GENERAL_NAME_value(gens, i);
    756 			if(gen->type == GEN_DIRNAME)
    757 				{
    758 				nm = gen->d.dirn;
    759 				break;
    760 				}
    761 			}
    762 		if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
    763 			return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
    764 		}
    765 	return X509_V_OK;
    766 	}
    767 
    768