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Microsoft JDBC Driver for SQL Server.
/*
* Microsoft JDBC Driver for SQL Server
*
* Copyright(c) Microsoft Corporation All rights reserved.
*
* This program is made available under the terms of the MIT License. See the LICENSE file in the project root for more information.
*/
package com.microsoft.sqlserver.jdbc;
import java.lang.reflect.Method;
import java.net.IDN;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.text.MessageFormat;
import java.util.Locale;
import java.util.logging.Level;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.naming.NamingException;
import javax.security.auth.Subject;
import javax.security.auth.login.Configuration;
import javax.security.auth.login.LoginContext;
import javax.security.auth.login.LoginException;
import org.ietf.jgss.GSSContext;
import org.ietf.jgss.GSSCredential;
import org.ietf.jgss.GSSException;
import org.ietf.jgss.GSSManager;
import org.ietf.jgss.GSSName;
import org.ietf.jgss.Oid;
import com.microsoft.sqlserver.jdbc.dns.DNSKerberosLocator;
/**
* KerbAuthentication for int auth.
*/
final class KerbAuthentication extends SSPIAuthentication {
private final static java.util.logging.Logger authLogger = java.util.logging.Logger
.getLogger("com.microsoft.sqlserver.jdbc.internals.KerbAuthentication");
private final SQLServerConnection con;
private final String spn;
private final GSSManager manager = GSSManager.getInstance();
private LoginContext lc = null;
private GSSCredential peerCredentials = null;
private GSSContext peerContext = null;
static {
// Overrides the default JAAS configuration loader.
// This one will forward to the default one in all cases but the default configuration is empty.
Configuration.setConfiguration(new JaasConfiguration(Configuration.getConfiguration()));
}
private void intAuthInit() throws SQLServerException {
try {
// If we need to support NTLM as well, we can use null
// Kerberos OID
Oid kerberos = new Oid("1.2.840.113554.1.2.2");
// http://blogs.sun.com/harcey/entry/of_java_kerberos_and_access
// We pass null to indicate that the system should interpret the SPN
// as it is.
GSSName remotePeerName = manager.createName(spn, null);
if (null != peerCredentials) {
peerContext = manager.createContext(remotePeerName, kerberos, peerCredentials, GSSContext.DEFAULT_LIFETIME);
peerContext.requestCredDeleg(false);
peerContext.requestMutualAuth(true);
peerContext.requestInteg(true);
}
else {
String configName = con.activeConnectionProperties.getProperty(SQLServerDriverStringProperty.JAAS_CONFIG_NAME.toString(),
SQLServerDriverStringProperty.JAAS_CONFIG_NAME.getDefaultValue());
Subject currentSubject;
KerbCallback callback = new KerbCallback(con);
try {
AccessControlContext context = AccessController.getContext();
currentSubject = Subject.getSubject(context);
if (null == currentSubject) {
lc = new LoginContext(configName, callback);
lc.login();
// per documentation LoginContext will instantiate a new subject.
currentSubject = lc.getSubject();
}
}
catch (LoginException le) {
if (authLogger.isLoggable(Level.FINE)) {
authLogger.fine(toString() + "Failed to login using Kerberos due to " + le.getClass().getName() + ":" + le.getMessage());
}
try {
// Not very clean since it raises an Exception, but we are sure we are cleaning well everything
con.terminate(SQLServerException.DRIVER_ERROR_NONE, SQLServerException.getErrString("R_integratedAuthenticationFailed"), le);
} catch (SQLServerException alwaysTriggered) {
String message = MessageFormat.format(SQLServerException.getErrString("R_kerberosLoginFailed"),
alwaysTriggered.getMessage(), le.getClass().getName(), le.getMessage());
if (callback.getUsernameRequested() != null) {
message = MessageFormat.format(SQLServerException.getErrString("R_kerberosLoginFailedForUsername"),
callback.getUsernameRequested(), message);
}
// By throwing Exception with LOGON_FAILED -> we avoid looping for connection
// In this case, authentication will never work anyway -> fail fast
throw new SQLServerException(message, alwaysTriggered.getSQLState(), SQLServerException.LOGON_FAILED, le);
}
return;
}
if (authLogger.isLoggable(Level.FINER)) {
authLogger.finer(toString() + " Getting client credentials");
}
peerCredentials = getClientCredential(currentSubject, manager, kerberos);
if (authLogger.isLoggable(Level.FINER)) {
authLogger.finer(toString() + " creating security context");
}
peerContext = manager.createContext(remotePeerName, kerberos, peerCredentials, GSSContext.DEFAULT_LIFETIME);
// The following flags should be inline with our native implementation.
peerContext.requestCredDeleg(true);
peerContext.requestMutualAuth(true);
peerContext.requestInteg(true);
}
}
catch (GSSException ge) {
authLogger.finer(toString() + "initAuthInit failed GSSException:-" + ge);
con.terminate(SQLServerException.DRIVER_ERROR_NONE, SQLServerException.getErrString("R_integratedAuthenticationFailed"), ge);
}
catch (PrivilegedActionException ge) {
authLogger.finer(toString() + "initAuthInit failed privileged exception:-" + ge);
con.terminate(SQLServerException.DRIVER_ERROR_NONE, SQLServerException.getErrString("R_integratedAuthenticationFailed"), ge);
}
}
// We have to do a privileged action to create the credential of the user in the current context
private static GSSCredential getClientCredential(final Subject subject,
final GSSManager MANAGER,
final Oid kerboid) throws PrivilegedActionException {
final PrivilegedExceptionAction action = new PrivilegedExceptionAction() {
public GSSCredential run() throws GSSException {
return MANAGER.createCredential(null // use the default principal
, GSSCredential.DEFAULT_LIFETIME, kerboid, GSSCredential.INITIATE_ONLY);
}
};
// TO support java 5, 6 we have to do this
// The signature for Java 5 returns an object 6 returns GSSCredential, immediate casting throws
// warning in Java 6.
Object credential = Subject.doAs(subject, action);
return (GSSCredential) credential;
}
private byte[] intAuthHandShake(byte[] pin,
boolean[] done) throws SQLServerException {
try {
if (authLogger.isLoggable(Level.FINER)) {
authLogger.finer(toString() + " Sending token to server over secure context");
}
byte[] byteToken = peerContext.initSecContext(pin, 0, pin.length);
if (peerContext.isEstablished()) {
done[0] = true;
if (authLogger.isLoggable(Level.FINER))
authLogger.finer(toString() + "Authentication done.");
}
else if (null == byteToken) {
// The documentation is not clear on when this can happen but it does say this could happen
if (authLogger.isLoggable(Level.INFO)) {
authLogger.info(toString() + "byteToken is null in initSecContext.");
}
con.terminate(SQLServerException.DRIVER_ERROR_NONE, SQLServerException.getErrString("R_integratedAuthenticationFailed"));
}
return byteToken;
}
catch (GSSException ge) {
authLogger.finer(toString() + "initSecContext Failed :-" + ge);
con.terminate(SQLServerException.DRIVER_ERROR_NONE, SQLServerException.getErrString("R_integratedAuthenticationFailed"), ge);
}
// keep the compiler happy
return null;
}
private String makeSpn(String server,
int port) throws SQLServerException {
if (authLogger.isLoggable(Level.FINER)) {
authLogger.finer(toString() + " Server: " + server + " port: " + port);
}
StringBuilder spn = new StringBuilder("MSSQLSvc/");
// Format is MSSQLSvc/myhost.domain.company.com:1433
// FQDN must be provided
if (con.serverNameAsACE()) {
spn.append(IDN.toASCII(server));
}
else {
spn.append(server);
}
spn.append(":");
spn.append(port);
String strSPN = spn.toString();
if (authLogger.isLoggable(Level.FINER)) {
authLogger.finer(toString() + " SPN: " + strSPN);
}
return strSPN;
}
// Package visible members below.
KerbAuthentication(SQLServerConnection con,
String address,
int port) throws SQLServerException {
this.con = con;
// Get user provided SPN string; if not provided then build the generic one
String userSuppliedServerSpn = con.activeConnectionProperties.getProperty(SQLServerDriverStringProperty.SERVER_SPN.toString());
String spn;
if (null != userSuppliedServerSpn) {
// serverNameAsACE is true, translate the user supplied serverSPN to ASCII
if (con.serverNameAsACE()) {
int slashPos = userSuppliedServerSpn.indexOf("/");
spn = userSuppliedServerSpn.substring(0, slashPos + 1) + IDN.toASCII(userSuppliedServerSpn.substring(slashPos + 1));
}
else {
spn = userSuppliedServerSpn;
}
}
else {
spn = makeSpn(address, port);
}
this.spn = enrichSpnWithRealm(spn, null == userSuppliedServerSpn);
if (!this.spn.equals(spn) && authLogger.isLoggable(Level.FINER)){
authLogger.finer(toString() + "SPN enriched: " + spn + " := " + this.spn);
}
}
private static final Pattern SPN_PATTERN = Pattern.compile("MSSQLSvc/(.*):([^:@]+)(@.+)?", Pattern.CASE_INSENSITIVE);
private String enrichSpnWithRealm(String spn,
boolean allowHostnameCanonicalization) {
if (spn == null) {
return spn;
}
Matcher m = SPN_PATTERN.matcher(spn);
if (!m.matches()) {
return spn;
}
if (m.group(3) != null) {
// Realm is already present, no need to enrich, the job has already been done
return spn;
}
String dnsName = m.group(1);
String portOrInstance = m.group(2);
RealmValidator realmValidator = getRealmValidator(dnsName);
String realm = findRealmFromHostname(realmValidator, dnsName);
if (realm == null && allowHostnameCanonicalization) {
// We failed, try with canonical host name to find a better match
try {
String canonicalHostName = InetAddress.getByName(dnsName).getCanonicalHostName();
realm = findRealmFromHostname(realmValidator, canonicalHostName);
// Since we have a match, our hostname is the correct one (for instance of server
// name was an IP), so we override dnsName as well
dnsName = canonicalHostName;
}
catch (UnknownHostException cannotCanonicalize) {
// ignored, but we are in a bad shape
}
}
if (realm == null) {
return spn;
}
else {
StringBuilder sb = new StringBuilder("MSSQLSvc/");
sb.append(dnsName).append(":").append(portOrInstance).append("@").append(realm.toUpperCase(Locale.ENGLISH));
return sb.toString();
}
}
private static RealmValidator validator;
/**
* Find a suitable way of validating a REALM for given JVM.
*
* @param hostnameToTest
* an example hostname we are gonna use to test our realm validator.
* @return a not null realm Validator.
*/
static RealmValidator getRealmValidator(String hostnameToTest) {
if (validator != null) {
return validator;
}
// JVM Specific, here Sun/Oracle JVM
try {
Class clz = Class.forName("sun.security.krb5.Config");
Method getInstance = clz.getMethod("getInstance", new Class[0]);
final Method getKDCList = clz.getMethod("getKDCList", new Class[] {String.class});
final Object instance = getInstance.invoke(null);
RealmValidator oracleRealmValidator = new RealmValidator() {
@Override
public boolean isRealmValid(String realm) {
try {
Object ret = getKDCList.invoke(instance, realm);
return ret != null;
}
catch (Exception err) {
return false;
}
}
};
validator = oracleRealmValidator;
// As explained here: https://github.com/Microsoft/mssql-jdbc/pull/40#issuecomment-281509304
// The default Oracle Resolution mechanism is not bulletproof
// If it resolves a non-existing name, drop it.
if (!validator.isRealmValid("this.might.not.exist." + hostnameToTest)) {
// Our realm validator is well working, return it
authLogger.fine("Kerberos Realm Validator: Using Built-in Oracle Realm Validation method.");
return oracleRealmValidator;
}
authLogger.fine("Kerberos Realm Validator: Detected buggy Oracle Realm Validator, using DNSKerberosLocator.");
}
catch (ReflectiveOperationException notTheRightJVMException) {
// Ignored, we simply are not using the right JVM
authLogger.fine("Kerberos Realm Validator: No Oracle Realm Validator Available, using DNSKerberosLocator.");
}
// No implementation found, default one, not any realm is valid
validator = new RealmValidator() {
@Override
public boolean isRealmValid(String realm) {
try {
return DNSKerberosLocator.isRealmValid(realm);
}
catch (NamingException err) {
return false;
}
}
};
return validator;
}
/**
* Try to find a REALM in the different parts of a host name.
*
* @param realmValidator
* a function that return true if REALM is valid and exists
* @param hostname
* the name we are looking a REALM for
* @return the realm if found, null otherwise
*/
private String findRealmFromHostname(RealmValidator realmValidator,
String hostname) {
if (hostname == null) {
return null;
}
int index = 0;
while (index != -1 && index < hostname.length() - 2) {
String realm = hostname.substring(index);
if (authLogger.isLoggable(Level.FINEST)) {
authLogger.finest(toString() + " looking up REALM candidate " + realm);
}
if (realmValidator.isRealmValid(realm)) {
return realm.toUpperCase();
}
index = hostname.indexOf(".", index + 1);
if (index != -1) {
index = index + 1;
}
}
return null;
}
/**
* JVM Specific implementation to decide whether a realm is valid or not
*/
interface RealmValidator {
boolean isRealmValid(String realm);
}
/**
*
* @param con
* @param address
* @param port
* @param ImpersonatedUserCred
* @throws SQLServerException
*/
KerbAuthentication(SQLServerConnection con,
String address,
int port,
GSSCredential ImpersonatedUserCred) throws SQLServerException {
this(con, address, port);
peerCredentials = ImpersonatedUserCred;
}
byte[] GenerateClientContext(byte[] pin,
boolean[] done) throws SQLServerException {
if (null == peerContext) {
intAuthInit();
}
return intAuthHandShake(pin, done);
}
int ReleaseClientContext() throws SQLServerException {
try {
if (null != peerCredentials)
peerCredentials.dispose();
if (null != peerContext)
peerContext.dispose();
if (null != lc)
lc.logout();
}
catch (LoginException e) {
// yes we are eating exceptions here but this should not fail in the normal circumstances and we do not want to eat previous
// login errors if caused before which is more useful to the user than the cleanup errors.
authLogger.fine(toString() + " Release of the credentials failed LoginException: " + e);
}
catch (GSSException e) {
// yes we are eating exceptions here but this should not fail in the normal circumstances and we do not want to eat previous
// login errors if caused before which is more useful to the user than the cleanup errors.
authLogger.fine(toString() + " Release of the credentials failed GSSException: " + e);
}
return 0;
}
}