v3_purp.c

开源的ssl算法openssl,版本0.9.8H

	if((bs=X509_get_ext_d2i(x, NID_basic_constraints, NULL, NULL))) {
		if(bs->ca) x->ex_flags |= EXFLAG_CA;
		if(bs->pathlen) {
			if((bs->pathlen->type == V_ASN1_NEG_INTEGER)
						|| !bs->ca) {
				x->ex_flags |= EXFLAG_INVALID;
				x->ex_pathlen = 0;
			} else x->ex_pathlen = ASN1_INTEGER_get(bs->pathlen);
		} else x->ex_pathlen = -1;
		BASIC_CONSTRAINTS_free(bs);
		x->ex_flags |= EXFLAG_BCONS;
	}
	/* Handle proxy certificates */
	if((pci=X509_get_ext_d2i(x, NID_proxyCertInfo, NULL, NULL))) {
		if (x->ex_flags & EXFLAG_CA
		    || X509_get_ext_by_NID(x, NID_subject_alt_name, 0) >= 0
		    || X509_get_ext_by_NID(x, NID_issuer_alt_name, 0) >= 0) {
			x->ex_flags |= EXFLAG_INVALID;
		}
		if (pci->pcPathLengthConstraint) {
			x->ex_pcpathlen =
				ASN1_INTEGER_get(pci->pcPathLengthConstraint);
		} else x->ex_pcpathlen = -1;
		PROXY_CERT_INFO_EXTENSION_free(pci);
		x->ex_flags |= EXFLAG_PROXY;
	}
	/* Handle key usage */
	if((usage=X509_get_ext_d2i(x, NID_key_usage, NULL, NULL))) {
		if(usage->length > 0) {
			x->ex_kusage = usage->data[0];
			if(usage->length > 1) 
				x->ex_kusage |= usage->data[1] << 8;
		} else x->ex_kusage = 0;
		x->ex_flags |= EXFLAG_KUSAGE;
		ASN1_BIT_STRING_free(usage);
	}
	x->ex_xkusage = 0;
	if((extusage=X509_get_ext_d2i(x, NID_ext_key_usage, NULL, NULL))) {
		x->ex_flags |= EXFLAG_XKUSAGE;
		for(i = 0; i < sk_ASN1_OBJECT_num(extusage); i++) {
			switch(OBJ_obj2nid(sk_ASN1_OBJECT_value(extusage,i))) {
				case NID_server_auth:
				x->ex_xkusage |= XKU_SSL_SERVER;
				break;

				case NID_client_auth:
				x->ex_xkusage |= XKU_SSL_CLIENT;
				break;

				case NID_email_protect:
				x->ex_xkusage |= XKU_SMIME;
				break;

				case NID_code_sign:
				x->ex_xkusage |= XKU_CODE_SIGN;
				break;

				case NID_ms_sgc:
				case NID_ns_sgc:
				x->ex_xkusage |= XKU_SGC;
				break;

				case NID_OCSP_sign:
				x->ex_xkusage |= XKU_OCSP_SIGN;
				break;

				case NID_time_stamp:
				x->ex_xkusage |= XKU_TIMESTAMP;
				break;

				case NID_dvcs:
				x->ex_xkusage |= XKU_DVCS;
				break;
			}
		}
		sk_ASN1_OBJECT_pop_free(extusage, ASN1_OBJECT_free);
	}

	if((ns=X509_get_ext_d2i(x, NID_netscape_cert_type, NULL, NULL))) {
		if(ns->length > 0) x->ex_nscert = ns->data[0];
		else x->ex_nscert = 0;
		x->ex_flags |= EXFLAG_NSCERT;
		ASN1_BIT_STRING_free(ns);
	}
	x->skid =X509_get_ext_d2i(x, NID_subject_key_identifier, NULL, NULL);
	x->akid =X509_get_ext_d2i(x, NID_authority_key_identifier, NULL, NULL);
#ifndef OPENSSL_NO_RFC3779
	x->rfc3779_addr =X509_get_ext_d2i(x, NID_sbgp_ipAddrBlock, NULL, NULL);
	x->rfc3779_asid =X509_get_ext_d2i(x, NID_sbgp_autonomousSysNum,
					  NULL, NULL);
#endif
	for (i = 0; i < X509_get_ext_count(x); i++)
		{
		ex = X509_get_ext(x, i);
		if (!X509_EXTENSION_get_critical(ex))
			continue;
		if (!X509_supported_extension(ex))
			{
			x->ex_flags |= EXFLAG_CRITICAL;
			break;
			}
		}
	x->ex_flags |= EXFLAG_SET;
}

/* CA checks common to all purposes
 * return codes:
 * 0 not a CA
 * 1 is a CA
 * 2 basicConstraints absent so "maybe" a CA
 * 3 basicConstraints absent but self signed V1.
 * 4 basicConstraints absent but keyUsage present and keyCertSign asserted.
 */

#define V1_ROOT (EXFLAG_V1|EXFLAG_SS)
#define ku_reject(x, usage) \
	(((x)->ex_flags & EXFLAG_KUSAGE) && !((x)->ex_kusage & (usage)))
#define xku_reject(x, usage) \
	(((x)->ex_flags & EXFLAG_XKUSAGE) && !((x)->ex_xkusage & (usage)))
#define ns_reject(x, usage) \
	(((x)->ex_flags & EXFLAG_NSCERT) && !((x)->ex_nscert & (usage)))

static int check_ca(const X509 *x)
{
	/* keyUsage if present should allow cert signing */
	if(ku_reject(x, KU_KEY_CERT_SIGN)) return 0;
	if(x->ex_flags & EXFLAG_BCONS) {
		if(x->ex_flags & EXFLAG_CA) return 1;
		/* If basicConstraints says not a CA then say so */
		else return 0;
	} else {
		/* we support V1 roots for...  uh, I don't really know why. */
		if((x->ex_flags & V1_ROOT) == V1_ROOT) return 3;
		/* If key usage present it must have certSign so tolerate it */
		else if (x->ex_flags & EXFLAG_KUSAGE) return 4;
		/* Older certificates could have Netscape-specific CA types */
		else if (x->ex_flags & EXFLAG_NSCERT
			 && x->ex_nscert & NS_ANY_CA) return 5;
		/* can this still be regarded a CA certificate?  I doubt it */
		return 0;
	}
}

int X509_check_ca(X509 *x)
{
	if(!(x->ex_flags & EXFLAG_SET)) {
		CRYPTO_w_lock(CRYPTO_LOCK_X509);
		x509v3_cache_extensions(x);
		CRYPTO_w_unlock(CRYPTO_LOCK_X509);
	}

	return check_ca(x);
}

/* Check SSL CA: common checks for SSL client and server */
static int check_ssl_ca(const X509 *x)
{
	int ca_ret;
	ca_ret = check_ca(x);
	if(!ca_ret) return 0;
	/* check nsCertType if present */
	if(ca_ret != 5 || x->ex_nscert & NS_SSL_CA) return ca_ret;
	else return 0;
}


static int check_purpose_ssl_client(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	if(xku_reject(x,XKU_SSL_CLIENT)) return 0;
	if(ca) return check_ssl_ca(x);
	/* We need to do digital signatures with it */
	if(ku_reject(x,KU_DIGITAL_SIGNATURE)) return 0;
	/* nsCertType if present should allow SSL client use */	
	if(ns_reject(x, NS_SSL_CLIENT)) return 0;
	return 1;
}

static int check_purpose_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	if(xku_reject(x,XKU_SSL_SERVER|XKU_SGC)) return 0;
	if(ca) return check_ssl_ca(x);

	if(ns_reject(x, NS_SSL_SERVER)) return 0;
	/* Now as for keyUsage: we'll at least need to sign OR encipher */
	if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_KEY_ENCIPHERMENT)) return 0;
	
	return 1;

}

static int check_purpose_ns_ssl_server(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	int ret;
	ret = check_purpose_ssl_server(xp, x, ca);
	if(!ret || ca) return ret;
	/* We need to encipher or Netscape complains */
	if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
	return ret;
}

/* common S/MIME checks */
static int purpose_smime(const X509 *x, int ca)
{
	if(xku_reject(x,XKU_SMIME)) return 0;
	if(ca) {
		int ca_ret;
		ca_ret = check_ca(x);
		if(!ca_ret) return 0;
		/* check nsCertType if present */
		if(ca_ret != 5 || x->ex_nscert & NS_SMIME_CA) return ca_ret;
		else return 0;
	}
	if(x->ex_flags & EXFLAG_NSCERT) {
		if(x->ex_nscert & NS_SMIME) return 1;
		/* Workaround for some buggy certificates */
		if(x->ex_nscert & NS_SSL_CLIENT) return 2;
		return 0;
	}
	return 1;
}

static int check_purpose_smime_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	int ret;
	ret = purpose_smime(x, ca);
	if(!ret || ca) return ret;
	if(ku_reject(x, KU_DIGITAL_SIGNATURE|KU_NON_REPUDIATION)) return 0;
	return ret;
}

static int check_purpose_smime_encrypt(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	int ret;
	ret = purpose_smime(x, ca);
	if(!ret || ca) return ret;
	if(ku_reject(x, KU_KEY_ENCIPHERMENT)) return 0;
	return ret;
}

static int check_purpose_crl_sign(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	if(ca) {
		int ca_ret;
		if((ca_ret = check_ca(x)) != 2) return ca_ret;
		else return 0;
	}
	if(ku_reject(x, KU_CRL_SIGN)) return 0;
	return 1;
}

/* OCSP helper: this is *not* a full OCSP check. It just checks that
 * each CA is valid. Additional checks must be made on the chain.
 */

static int ocsp_helper(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	/* Must be a valid CA.  Should we really support the "I don't know"
	   value (2)? */
	if(ca) return check_ca(x);
	/* leaf certificate is checked in OCSP_verify() */
	return 1;
}

static int no_check(const X509_PURPOSE *xp, const X509 *x, int ca)
{
	return 1;
}

/* Various checks to see if one certificate issued the second.
 * This can be used to prune a set of possible issuer certificates
 * which have been looked up using some simple method such as by
 * subject name.
 * These are:
 * 1. Check issuer_name(subject) == subject_name(issuer)
 * 2. If akid(subject) exists check it matches issuer
 * 3. If key_usage(issuer) exists check it supports certificate signing
 * returns 0 for OK, positive for reason for mismatch, reasons match
 * codes for X509_verify_cert()
 */

int X509_check_issued(X509 *issuer, X509 *subject)
{
	if(X509_NAME_cmp(X509_get_subject_name(issuer),
			X509_get_issuer_name(subject)))
				return X509_V_ERR_SUBJECT_ISSUER_MISMATCH;
	x509v3_cache_extensions(issuer);
	x509v3_cache_extensions(subject);
	if(subject->akid) {
		/* Check key ids (if present) */
		if(subject->akid->keyid && issuer->skid &&
		 ASN1_OCTET_STRING_cmp(subject->akid->keyid, issuer->skid) )
				return X509_V_ERR_AKID_SKID_MISMATCH;
		/* Check serial number */
		if(subject->akid->serial &&
			ASN1_INTEGER_cmp(X509_get_serialNumber(issuer),
						subject->akid->serial))
				return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
		/* Check issuer name */
		if(subject->akid->issuer) {
			/* Ugh, for some peculiar reason AKID includes
			 * SEQUENCE OF GeneralName. So look for a DirName.
			 * There may be more than one but we only take any
			 * notice of the first.
			 */
			GENERAL_NAMES *gens;
			GENERAL_NAME *gen;
			X509_NAME *nm = NULL;
			int i;
			gens = subject->akid->issuer;
			for(i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
				gen = sk_GENERAL_NAME_value(gens, i);
				if(gen->type == GEN_DIRNAME) {
					nm = gen->d.dirn;
					break;
				}
			}
			if(nm && X509_NAME_cmp(nm, X509_get_issuer_name(issuer)))
				return X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH;
		}
	}
	if(subject->ex_flags & EXFLAG_PROXY)
		{
		if(ku_reject(issuer, KU_DIGITAL_SIGNATURE))
			return X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE;
		}
	else if(ku_reject(issuer, KU_KEY_CERT_SIGN))
		return X509_V_ERR_KEYUSAGE_NO_CERTSIGN;
	return X509_V_OK;
}