/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at
* trunk/opends/resource/legal-notices/OpenDS.LICENSE
* or https://OpenDS.dev.java.net/OpenDS.LICENSE.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at
* trunk/opends/resource/legal-notices/OpenDS.LICENSE. If applicable,
* add the following below this CDDL HEADER, with the fields enclosed
* by brackets "[]" replaced with your own identifying information:
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*
*
* Copyright 2006-2009 Sun Microsystems, Inc.
* Portions copyright 2011-2013 ForgeRock AS.
*/
package org.opends.server.extensions;
import java.security.MessageDigest;
import java.security.SecureRandom;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.locks.Lock;
import org.opends.messages.Message;
import org.opends.server.admin.server.ConfigurationChangeListener;
import org.opends.server.admin.std.server.CramMD5SASLMechanismHandlerCfg;
import org.opends.server.admin.std.server.SASLMechanismHandlerCfg;
import org.opends.server.api.*;
import org.opends.server.config.ConfigException;
import org.opends.server.core.BindOperation;
import org.opends.server.core.DirectoryServer;
import org.opends.server.core.PasswordPolicyState;
import org.opends.server.loggers.debug.DebugTracer;
import org.opends.server.types.*;
import static org.opends.messages.ExtensionMessages.*;
import static org.opends.server.loggers.debug.DebugLogger.*;
import static org.opends.server.util.ServerConstants.*;
import static org.opends.server.util.StaticUtils.*;
/**
* This class provides an implementation of a SASL mechanism that uses digest
* authentication via CRAM-MD5. This is a password-based mechanism that does
* not expose the password itself over the wire but rather uses an MD5 hash that
* proves the client knows the password. This is similar to the DIGEST-MD5
* mechanism, and the primary differences are that CRAM-MD5 only obtains random
* data from the server (whereas DIGEST-MD5 uses random data from both the
* server and the client), CRAM-MD5 does not allow for an authorization ID in
* addition to the authentication ID where DIGEST-MD5 does, and CRAM-MD5 does
* not define any integrity and confidentiality mechanisms where DIGEST-MD5
* does. This implementation is based on the proposal defined in
* draft-ietf-sasl-crammd5-05.
*/
public class CRAMMD5SASLMechanismHandler
extends SASLMechanismHandler<CramMD5SASLMechanismHandlerCfg>
implements ConfigurationChangeListener<
CramMD5SASLMechanismHandlerCfg>
{
/**
* The tracer object for the debug logger.
*/
private static final DebugTracer TRACER = getTracer();
// An array filled with the inner pad byte.
private byte[] iPad;
// An array filled with the outer pad byte.
private byte[] oPad;
// The current configuration for this SASL mechanism handler.
private CramMD5SASLMechanismHandlerCfg currentConfig;
// The identity mapper that will be used to map ID strings to user entries.
private IdentityMapper<?> identityMapper;
// The message digest engine that will be used to create the MD5 digests.
private MessageDigest md5Digest;
// The lock that will be used to provide threadsafe access to the message
// digest.
private Object digestLock;
// The random number generator that we will use to create the server
// challenge.
private SecureRandom randomGenerator;
/**
* Creates a new instance of this SASL mechanism handler. No initialization
* should be done in this method, as it should all be performed in the
* <CODE>initializeSASLMechanismHandler</CODE> method.
*/
public CRAMMD5SASLMechanismHandler()
{
super();
}
/**
* {@inheritDoc}
*/
@Override()
public void initializeSASLMechanismHandler(
CramMD5SASLMechanismHandlerCfg configuration)
throws ConfigException, InitializationException
{
configuration.addCramMD5ChangeListener(this);
currentConfig = configuration;
// Initialize the variables needed for the MD5 digest creation.
digestLock = new Object();
randomGenerator = new SecureRandom();
try
{
md5Digest = MessageDigest.getInstance("MD5");
}
catch (Exception e)
{
if (debugEnabled())
{
TRACER.debugCaught(DebugLogLevel.ERROR, e);
}
Message message =
ERR_SASLCRAMMD5_CANNOT_GET_MESSAGE_DIGEST.get(getExceptionMessage(e));
throw new InitializationException(message, e);
}
// Create and fill the iPad and oPad arrays.
iPad = new byte[HMAC_MD5_BLOCK_LENGTH];
oPad = new byte[HMAC_MD5_BLOCK_LENGTH];
Arrays.fill(iPad, CRAMMD5_IPAD_BYTE);
Arrays.fill(oPad, CRAMMD5_OPAD_BYTE);
// Get the identity mapper that should be used to find users.
DN identityMapperDN = configuration.getIdentityMapperDN();
identityMapper = DirectoryServer.getIdentityMapper(identityMapperDN);
DirectoryServer.registerSASLMechanismHandler(SASL_MECHANISM_CRAM_MD5, this);
}
/**
* {@inheritDoc}
*/
@Override()
public void finalizeSASLMechanismHandler()
{
currentConfig.removeCramMD5ChangeListener(this);
DirectoryServer.deregisterSASLMechanismHandler(SASL_MECHANISM_CRAM_MD5);
}
/**
* {@inheritDoc}
*/
@Override()
public void processSASLBind(BindOperation bindOperation)
{
// The CRAM-MD5 bind process uses two stages. See if the client provided
// any credentials. If not, then we're in the first stage so we'll send the
// challenge to the client.
ByteString clientCredentials = bindOperation.getSASLCredentials();
ClientConnection clientConnection = bindOperation.getClientConnection();
if (clientCredentials == null)
{
// The client didn't provide any credentials, so this is the initial
// request. Generate some random data to send to the client as the
// challenge and store it in the client connection so we can verify the
// credentials provided by the client later.
byte[] challengeBytes = new byte[16];
randomGenerator.nextBytes(challengeBytes);
StringBuilder challengeString = new StringBuilder(18);
challengeString.append('<');
for (byte b : challengeBytes)
{
challengeString.append(byteToLowerHex(b));
}
challengeString.append('>');
ByteString challenge =
ByteString.valueOf(challengeString.toString());
clientConnection.setSASLAuthStateInfo(challenge);
bindOperation.setServerSASLCredentials(challenge);
bindOperation.setResultCode(ResultCode.SASL_BIND_IN_PROGRESS);
return;
}
// If we've gotten here, then the client did provide credentials. First,
// make sure that we have a stored version of the credentials associated
// with the client connection. If not, then it likely means that the client
// is trying to pull a fast one on us.
Object saslStateInfo = clientConnection.getSASLAuthStateInfo();
if (saslStateInfo == null)
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_NO_STORED_CHALLENGE.get();
bindOperation.setAuthFailureReason(message);
return;
}
if (! (saslStateInfo instanceof ByteString))
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_INVALID_STORED_CHALLENGE.get();
bindOperation.setAuthFailureReason(message);
return;
}
ByteString challenge = (ByteString) saslStateInfo;
// Wipe out the stored challenge so it can't be used again.
clientConnection.setSASLAuthStateInfo(null);
// Now look at the client credentials and make sure that we can decode them.
// It should be a username followed by a space and a digest string. Since
// the username itself may contain spaces but the digest string may not,
// look for the last space and use it as the delimiter.
String credString = clientCredentials.toString();
int spacePos = credString.lastIndexOf(' ');
if (spacePos < 0)
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_NO_SPACE_IN_CREDENTIALS.get();
bindOperation.setAuthFailureReason(message);
return;
}
String userName = credString.substring(0, spacePos);
String digest = credString.substring(spacePos+1);
// Look at the digest portion of the provided credentials. It must have a
// length of exactly 32 bytes and be comprised only of hex characters.
if (digest.length() != (2*MD5_DIGEST_LENGTH))
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_INVALID_DIGEST_LENGTH.get(
digest.length(),
(2*MD5_DIGEST_LENGTH));
bindOperation.setAuthFailureReason(message);
return;
}
byte[] digestBytes;
try
{
digestBytes = hexStringToByteArray(digest);
}
catch (ParseException pe)
{
if (debugEnabled())
{
TRACER.debugCaught(DebugLogLevel.ERROR, pe);
}
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_INVALID_DIGEST_CONTENT.get(
pe.getMessage());
bindOperation.setAuthFailureReason(message);
return;
}
// Get the user entry for the authentication ID. Allow for an
// authentication ID that is just a username (as per the CRAM-MD5 spec), but
// also allow a value in the authzid form specified in RFC 2829.
Entry userEntry = null;
String lowerUserName = toLowerCase(userName);
if (lowerUserName.startsWith("dn:"))
{
// Try to decode the user DN and retrieve the corresponding entry.
DN userDN;
try
{
userDN = DN.decode(userName.substring(3));
}
catch (DirectoryException de)
{
if (debugEnabled())
{
TRACER.debugCaught(DebugLogLevel.ERROR, de);
}
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_CANNOT_DECODE_USERNAME_AS_DN.get(
userName, de.getMessageObject());
bindOperation.setAuthFailureReason(message);
return;
}
if (userDN.isNullDN())
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_USERNAME_IS_NULL_DN.get();
bindOperation.setAuthFailureReason(message);
return;
}
DN rootDN = DirectoryServer.getActualRootBindDN(userDN);
if (rootDN != null)
{
userDN = rootDN;
}
// Acquire a read lock on the user entry. If this fails, then so will the
// authentication.
final Lock readLock = LockManager.lockRead(userDN);
if (readLock == null)
{
bindOperation.setResultCode(ResultCode.BUSY);
bindOperation.setAuthFailureReason(INFO_SASLCRAMMD5_CANNOT_LOCK_ENTRY
.get(String.valueOf(userDN)));
return;
}
try
{
userEntry = DirectoryServer.getEntry(userDN);
}
catch (DirectoryException de)
{
if (debugEnabled())
{
TRACER.debugCaught(DebugLogLevel.ERROR, de);
}
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_CANNOT_GET_ENTRY_BY_DN.get(
String.valueOf(userDN), de.getMessageObject());
bindOperation.setAuthFailureReason(message);
return;
}
finally
{
LockManager.unlock(userDN, readLock);
}
}
else
{
// Use the identity mapper to resolve the username to an entry.
if (lowerUserName.startsWith("u:"))
{
userName = userName.substring(2);
}
try
{
userEntry = identityMapper.getEntryForID(userName);
}
catch (DirectoryException de)
{
if (debugEnabled())
{
TRACER.debugCaught(DebugLogLevel.ERROR, de);
}
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_CANNOT_MAP_USERNAME.get(
String.valueOf(userName), de.getMessageObject());
bindOperation.setAuthFailureReason(message);
return;
}
}
// At this point, we should have a user entry. If we don't then fail.
if (userEntry == null)
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_NO_MATCHING_ENTRIES.get(userName);
bindOperation.setAuthFailureReason(message);
return;
}
else
{
bindOperation.setSASLAuthUserEntry(userEntry);
}
// Get the clear-text passwords from the user entry, if there are any.
List<ByteString> clearPasswords;
try
{
AuthenticationPolicyState authState = AuthenticationPolicyState.forUser(
userEntry, false);
if (!authState.isPasswordPolicy())
{
bindOperation.setResultCode(ResultCode.INAPPROPRIATE_AUTHENTICATION);
Message message = ERR_SASL_ACCOUNT_NOT_LOCAL
.get(SASL_MECHANISM_CRAM_MD5, String.valueOf(userEntry.getDN()));
bindOperation.setAuthFailureReason(message);
return;
}
PasswordPolicyState pwPolicyState = (PasswordPolicyState) authState;
clearPasswords = pwPolicyState.getClearPasswords();
if ((clearPasswords == null) || clearPasswords.isEmpty())
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_NO_REVERSIBLE_PASSWORDS.get(
String.valueOf(userEntry.getDN()));
bindOperation.setAuthFailureReason(message);
return;
}
}
catch (Exception e)
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_CANNOT_GET_REVERSIBLE_PASSWORDS.get(
String.valueOf(userEntry.getDN()),
String.valueOf(e));
bindOperation.setAuthFailureReason(message);
return;
}
// Iterate through the clear-text values and see if any of them can be used
// in conjunction with the challenge to construct the provided digest.
boolean matchFound = false;
for (ByteString clearPassword : clearPasswords)
{
byte[] generatedDigest = generateDigest(clearPassword, challenge);
if (Arrays.equals(digestBytes, generatedDigest))
{
matchFound = true;
break;
}
}
if (! matchFound)
{
bindOperation.setResultCode(ResultCode.INVALID_CREDENTIALS);
Message message = ERR_SASLCRAMMD5_INVALID_PASSWORD.get();
bindOperation.setAuthFailureReason(message);
return;
}
// If we've gotten here, then the authentication was successful.
bindOperation.setResultCode(ResultCode.SUCCESS);
AuthenticationInfo authInfo =
new AuthenticationInfo(userEntry, SASL_MECHANISM_CRAM_MD5,
clientCredentials,
DirectoryServer.isRootDN(userEntry.getDN()));
bindOperation.setAuthenticationInfo(authInfo);
return;
}
/**
* Generates the appropriate HMAC-MD5 digest for a CRAM-MD5 authentication
* with the given information.
*
* @param password The clear-text password to use when generating the
* digest.
* @param challenge The server-supplied challenge to use when generating the
* digest.
*
* @return The generated HMAC-MD5 digest for CRAM-MD5 authentication.
*/
private byte[] generateDigest(ByteString password, ByteString challenge)
{
// Get the byte arrays backing the password and challenge.
byte[] p = password.toByteArray();
byte[] c = challenge.toByteArray();
// Grab a lock to protect the MD5 digest generation.
synchronized (digestLock)
{
// If the password is longer than the HMAC-MD5 block length, then use an
// MD5 digest of the password rather than the password itself.
if (p.length > HMAC_MD5_BLOCK_LENGTH)
{
p = md5Digest.digest(p);
}
// Create byte arrays with data needed for the hash generation.
byte[] iPadAndData = new byte[HMAC_MD5_BLOCK_LENGTH + c.length];
System.arraycopy(iPad, 0, iPadAndData, 0, HMAC_MD5_BLOCK_LENGTH);
System.arraycopy(c, 0, iPadAndData, HMAC_MD5_BLOCK_LENGTH, c.length);
byte[] oPadAndHash = new byte[HMAC_MD5_BLOCK_LENGTH + MD5_DIGEST_LENGTH];
System.arraycopy(oPad, 0, oPadAndHash, 0, HMAC_MD5_BLOCK_LENGTH);
// Iterate through the bytes in the key and XOR them with the iPad and
// oPad as appropriate.
for (int i=0; i < p.length; i++)
{
iPadAndData[i] ^= p[i];
oPadAndHash[i] ^= p[i];
}
// Copy an MD5 digest of the iPad-XORed key and the data into the array to
// be hashed.
System.arraycopy(md5Digest.digest(iPadAndData), 0, oPadAndHash,
HMAC_MD5_BLOCK_LENGTH, MD5_DIGEST_LENGTH);
// Return an MD5 digest of the resulting array.
return md5Digest.digest(oPadAndHash);
}
}
/**
* {@inheritDoc}
*/
@Override()
public boolean isPasswordBased(String mechanism)
{
// This is a password-based mechanism.
return true;
}
/**
* {@inheritDoc}
*/
@Override()
public boolean isSecure(String mechanism)
{
// This may be considered a secure mechanism.
return true;
}
/**
* {@inheritDoc}
*/
@Override()
public boolean isConfigurationAcceptable(
SASLMechanismHandlerCfg configuration,
List<Message> unacceptableReasons)
{
CramMD5SASLMechanismHandlerCfg config =
(CramMD5SASLMechanismHandlerCfg) configuration;
return isConfigurationChangeAcceptable(config, unacceptableReasons);
}
/**
* {@inheritDoc}
*/
@Override
public boolean isConfigurationChangeAcceptable(
CramMD5SASLMechanismHandlerCfg configuration,
List<Message> unacceptableReasons)
{
return true;
}
/**
* {@inheritDoc}
*/
@Override
public ConfigChangeResult applyConfigurationChange(
CramMD5SASLMechanismHandlerCfg configuration)
{
ResultCode resultCode = ResultCode.SUCCESS;
boolean adminActionRequired = false;
ArrayList<Message> messages = new ArrayList<Message>();
DN identityMapperDN = configuration.getIdentityMapperDN();
identityMapper = DirectoryServer.getIdentityMapper(identityMapperDN);
currentConfig = configuration;
return new ConfigChangeResult(resultCode, adminActionRequired, messages);
}
}