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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package sun.security.validator;
import java.util.*;
import java.security.cert.*;
import sun.security.x509.NetscapeCertTypeExtension;
/**
* Class to check if an end entity cert is suitable for use in some
* context.<p>
*
* This class is used internally by the validator. Currently, seven variants
* are supported defined as VAR_XXX constants in the Validator class:
* <ul>
* <li>Generic. No additional requirements, all certificates are ok.
*
* <li>TLS server. Requires that a String parameter is passed to
* validate that specifies the name of the TLS key exchange algorithm
* in use. See the JSSE X509TrustManager spec for details.
*
* <li>TLS client.
*
* <li>Code signing.
*
* <li>JCE code signing. Some early JCE code signing certs issued to
* providers had incorrect extensions. In this mode the checks
* are relaxed compared to standard code signing checks in order to
* allow these certificates to pass.
*
* <li>Plugin code signing. WebStart and Plugin require their own variant
* which is equivalent to VAR_CODE_SIGNING with additional checks for
* compatibility/special cases. See also PKIXValidator.
*
* <li>TSA Server (see RFC 3161, section 2.3).
*
* </ul>
*
* @author Andreas Sterbenz
*/
class EndEntityChecker {
// extended key usage OIDs for TLS server, TLS client, code signing
// and any usage
private final static String OID_EXTENDED_KEY_USAGE =
SimpleValidator.OID_EXTENDED_KEY_USAGE;
private final static String OID_EKU_TLS_SERVER = "1.3.6.1.5.5.7.3.1";
private final static String OID_EKU_TLS_CLIENT = "1.3.6.1.5.5.7.3.2";
private final static String OID_EKU_CODE_SIGNING = "1.3.6.1.5.5.7.3.3";
private final static String OID_EKU_TIME_STAMPING = "1.3.6.1.5.5.7.3.8";
private final static String OID_EKU_ANY_USAGE = "2.5.29.37.0";
// the Netscape Server-Gated-Cryptography EKU extension OID
private final static String OID_EKU_NS_SGC = "2.16.840.1.113730.4.1";
// the Microsoft Server-Gated-Cryptography EKU extension OID
private final static String OID_EKU_MS_SGC = "1.3.6.1.4.1.311.10.3.3";
// the recognized extension OIDs
private final static String OID_SUBJECT_ALT_NAME = "2.5.29.17";
private final static String NSCT_SSL_CLIENT =
NetscapeCertTypeExtension.SSL_CLIENT;
private final static String NSCT_SSL_SERVER =
NetscapeCertTypeExtension.SSL_SERVER;
private final static String NSCT_CODE_SIGNING =
NetscapeCertTypeExtension.OBJECT_SIGNING;
// bit numbers in the key usage extension
private final static int KU_SIGNATURE = 0;
private final static int KU_KEY_ENCIPHERMENT = 2;
private final static int KU_KEY_AGREEMENT = 4;
// TLS key exchange algorithms requiring digitalSignature key usage
private final static Collection<String> KU_SERVER_SIGNATURE =
Arrays.asList("DHE_DSS", "DHE_RSA", "ECDHE_ECDSA", "ECDHE_RSA",
"RSA_EXPORT", "UNKNOWN");
// TLS key exchange algorithms requiring keyEncipherment key usage
private final static Collection<String> KU_SERVER_ENCRYPTION =
Arrays.asList("RSA");
// TLS key exchange algorithms requiring keyAgreement key usage
private final static Collection<String> KU_SERVER_KEY_AGREEMENT =
Arrays.asList("DH_DSS", "DH_RSA", "ECDH_ECDSA", "ECDH_RSA");
// variant of this end entity cert checker
private final String variant;
// type of the validator this checker belongs to
private final String type;
private EndEntityChecker(String type, String variant) {
this.type = type;
this.variant = variant;
}
static EndEntityChecker getInstance(String type, String variant) {
return new EndEntityChecker(type, variant);
}
void check(X509Certificate cert, Object parameter)
throws CertificateException {
if (variant.equals(Validator.VAR_GENERIC)) {
// no checks
return;
} else if (variant.equals(Validator.VAR_TLS_SERVER)) {
checkTLSServer(cert, (String)parameter);
} else if (variant.equals(Validator.VAR_TLS_CLIENT)) {
checkTLSClient(cert);
} else if (variant.equals(Validator.VAR_CODE_SIGNING)) {
checkCodeSigning(cert);
} else if (variant.equals(Validator.VAR_JCE_SIGNING)) {
checkCodeSigning(cert);
} else if (variant.equals(Validator.VAR_PLUGIN_CODE_SIGNING)) {
checkCodeSigning(cert);
} else if (variant.equals(Validator.VAR_TSA_SERVER)) {
checkTSAServer(cert);
} else {
throw new CertificateException("Unknown variant: " + variant);
}
}
/**
* Utility method returning the Set of critical extensions for
* certificate cert (never null).
*/
private Set<String> getCriticalExtensions(X509Certificate cert) {
Set<String> exts = cert.getCriticalExtensionOIDs();
if (exts == null) {
exts = Collections.emptySet();
}
return exts;
}
/**
* Utility method checking if there are any unresolved critical extensions.
* @throws CertificateException if so.
*/
private void checkRemainingExtensions(Set<String> exts)
throws CertificateException {
// basic constraints irrelevant in EE certs
exts.remove(SimpleValidator.OID_BASIC_CONSTRAINTS);
// If the subject field contains an empty sequence, the subjectAltName
// extension MUST be marked critical.
// We do not check the validity of the critical extension, just mark
// it recognizable here.
exts.remove(OID_SUBJECT_ALT_NAME);
if (!exts.isEmpty()) {
throw new CertificateException("Certificate contains unsupported "
+ "critical extensions: " + exts);
}
}
/**
* Utility method checking if the extended key usage extension in
* certificate cert allows use for expectedEKU.
*/
private boolean checkEKU(X509Certificate cert, Set<String> exts,
String expectedEKU) throws CertificateException {
List<String> eku = cert.getExtendedKeyUsage();
if (eku == null) {
return true;
}
return eku.contains(expectedEKU) || eku.contains(OID_EKU_ANY_USAGE);
}
/**
* Utility method checking if bit 'bit' is set in this certificates
* key usage extension.
* @throws CertificateException if not
*/
private boolean checkKeyUsage(X509Certificate cert, int bit)
throws CertificateException {
boolean[] keyUsage = cert.getKeyUsage();
if (keyUsage == null) {
return true;
}
return (keyUsage.length > bit) && keyUsage[bit];
}
/**
* Check whether this certificate can be used for TLS client
* authentication.
* @throws CertificateException if not.
*/
private void checkTLSClient(X509Certificate cert)
throws CertificateException {
Set<String> exts = getCriticalExtensions(cert);
if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
throw new ValidatorException
("KeyUsage does not allow digital signatures",
ValidatorException.T_EE_EXTENSIONS, cert);
}
if (checkEKU(cert, exts, OID_EKU_TLS_CLIENT) == false) {
throw new ValidatorException("Extended key usage does not "
+ "permit use for TLS client authentication",
ValidatorException.T_EE_EXTENSIONS, cert);
}
if (!SimpleValidator.getNetscapeCertTypeBit(cert, NSCT_SSL_CLIENT)) {
throw new ValidatorException
("Netscape cert type does not permit use for SSL client",
ValidatorException.T_EE_EXTENSIONS, cert);
}
// remove extensions we checked
exts.remove(SimpleValidator.OID_KEY_USAGE);
exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
exts.remove(SimpleValidator.OID_NETSCAPE_CERT_TYPE);
checkRemainingExtensions(exts);
}
/**
* Check whether this certificate can be used for TLS server authentication
* using the specified authentication type parameter. See X509TrustManager
* specification for details.
* @throws CertificateException if not.
*/
private void checkTLSServer(X509Certificate cert, String parameter)
throws CertificateException {
Set<String> exts = getCriticalExtensions(cert);
if (KU_SERVER_ENCRYPTION.contains(parameter)) {
if (checkKeyUsage(cert, KU_KEY_ENCIPHERMENT) == false) {
throw new ValidatorException
("KeyUsage does not allow key encipherment",
ValidatorException.T_EE_EXTENSIONS, cert);
}
} else if (KU_SERVER_SIGNATURE.contains(parameter)) {
if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
throw new ValidatorException
("KeyUsage does not allow digital signatures",
ValidatorException.T_EE_EXTENSIONS, cert);
}
} else if (KU_SERVER_KEY_AGREEMENT.contains(parameter)) {
if (checkKeyUsage(cert, KU_KEY_AGREEMENT) == false) {
throw new ValidatorException
("KeyUsage does not allow key agreement",
ValidatorException.T_EE_EXTENSIONS, cert);
}
} else {
throw new CertificateException("Unknown authType: " + parameter);
}
if (checkEKU(cert, exts, OID_EKU_TLS_SERVER) == false) {
// check for equivalent but now obsolete Server-Gated-Cryptography
// (aka Step-Up, 128 bit) EKU OIDs
if ((checkEKU(cert, exts, OID_EKU_MS_SGC) == false) &&
(checkEKU(cert, exts, OID_EKU_NS_SGC) == false)) {
throw new ValidatorException
("Extended key usage does not permit use for TLS "
+ "server authentication",
ValidatorException.T_EE_EXTENSIONS, cert);
}
}
if (!SimpleValidator.getNetscapeCertTypeBit(cert, NSCT_SSL_SERVER)) {
throw new ValidatorException
("Netscape cert type does not permit use for SSL server",
ValidatorException.T_EE_EXTENSIONS, cert);
}
// remove extensions we checked
exts.remove(SimpleValidator.OID_KEY_USAGE);
exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
exts.remove(SimpleValidator.OID_NETSCAPE_CERT_TYPE);
checkRemainingExtensions(exts);
}
/**
* Check whether this certificate can be used for code signing.
* @throws CertificateException if not.
*/
private void checkCodeSigning(X509Certificate cert)
throws CertificateException {
Set<String> exts = getCriticalExtensions(cert);
if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
throw new ValidatorException
("KeyUsage does not allow digital signatures",
ValidatorException.T_EE_EXTENSIONS, cert);
}
if (checkEKU(cert, exts, OID_EKU_CODE_SIGNING) == false) {
throw new ValidatorException
("Extended key usage does not permit use for code signing",
ValidatorException.T_EE_EXTENSIONS, cert);
}
// do not check Netscape cert type for JCE code signing checks
// (some certs were issued with incorrect extensions)
if (variant.equals(Validator.VAR_JCE_SIGNING) == false) {
if (!SimpleValidator.getNetscapeCertTypeBit(cert, NSCT_CODE_SIGNING)) {
throw new ValidatorException
("Netscape cert type does not permit use for code signing",
ValidatorException.T_EE_EXTENSIONS, cert);
}
exts.remove(SimpleValidator.OID_NETSCAPE_CERT_TYPE);
}
// remove extensions we checked
exts.remove(SimpleValidator.OID_KEY_USAGE);
exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
checkRemainingExtensions(exts);
}
/**
* Check whether this certificate can be used by a time stamping authority
* server (see RFC 3161, section 2.3).
* @throws CertificateException if not.
*/
private void checkTSAServer(X509Certificate cert)
throws CertificateException {
Set<String> exts = getCriticalExtensions(cert);
if (checkKeyUsage(cert, KU_SIGNATURE) == false) {
throw new ValidatorException
("KeyUsage does not allow digital signatures",
ValidatorException.T_EE_EXTENSIONS, cert);
}
if (cert.getExtendedKeyUsage() == null) {
throw new ValidatorException
("Certificate does not contain an extended key usage " +
"extension required for a TSA server",
ValidatorException.T_EE_EXTENSIONS, cert);
}
if (checkEKU(cert, exts, OID_EKU_TIME_STAMPING) == false) {
throw new ValidatorException
("Extended key usage does not permit use for TSA server",
ValidatorException.T_EE_EXTENSIONS, cert);
}
// remove extensions we checked
exts.remove(SimpleValidator.OID_KEY_USAGE);
exts.remove(SimpleValidator.OID_EXTENDED_KEY_USAGE);
checkRemainingExtensions(exts);
}
}