/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.kafka.common.security.scram;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Map;
import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;
import javax.security.sasl.SaslClient;
import javax.security.sasl.SaslClientFactory;
import javax.security.sasl.SaslException;
import org.apache.kafka.common.errors.IllegalSaslStateException;
import org.apache.kafka.common.security.scram.ScramMessages.ClientFinalMessage;
import org.apache.kafka.common.security.scram.ScramMessages.ServerFinalMessage;
import org.apache.kafka.common.security.scram.ScramMessages.ServerFirstMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* SaslClient implementation for SASL/SCRAM.
* <p>
* This implementation expects a login module that populates username as
* the Subject's public credential and password as the private credential.
*
* @see <a href="https://tools.ietf.org/html/rfc5802">RFC 5802</a>
*
*/
public class ScramSaslClient implements SaslClient {
private static final Logger log = LoggerFactory.getLogger(ScramSaslClient.class);
enum State {
SEND_CLIENT_FIRST_MESSAGE,
RECEIVE_SERVER_FIRST_MESSAGE,
RECEIVE_SERVER_FINAL_MESSAGE,
COMPLETE,
FAILED
};
private final ScramMechanism mechanism;
private final CallbackHandler callbackHandler;
private final ScramFormatter formatter;
private String clientNonce;
private State state;
private byte[] saltedPassword;
private ScramMessages.ClientFirstMessage clientFirstMessage;
private ScramMessages.ServerFirstMessage serverFirstMessage;
private ScramMessages.ClientFinalMessage clientFinalMessage;
public ScramSaslClient(ScramMechanism mechanism, CallbackHandler cbh) throws NoSuchAlgorithmException {
this.mechanism = mechanism;
this.callbackHandler = cbh;
this.formatter = new ScramFormatter(mechanism);
setState(State.SEND_CLIENT_FIRST_MESSAGE);
}
@Override
public String getMechanismName() {
return mechanism.mechanismName();
}
@Override
public boolean hasInitialResponse() {
return true;
}
@Override
public byte[] evaluateChallenge(byte[] challenge) throws SaslException {
try {
switch (state) {
case SEND_CLIENT_FIRST_MESSAGE:
if (challenge != null && challenge.length != 0)
throw new SaslException("Expected empty challenge");
clientNonce = formatter.secureRandomString();
NameCallback nameCallback = new NameCallback("Name:");
try {
callbackHandler.handle(new Callback[]{nameCallback});
} catch (IOException | UnsupportedCallbackException e) {
throw new SaslException("User name could not be obtained", e);
}
String username = nameCallback.getName();
String saslName = formatter.saslName(username);
this.clientFirstMessage = new ScramMessages.ClientFirstMessage(saslName, clientNonce);
setState(State.RECEIVE_SERVER_FIRST_MESSAGE);
return clientFirstMessage.toBytes();
case RECEIVE_SERVER_FIRST_MESSAGE:
this.serverFirstMessage = new ServerFirstMessage(challenge);
if (!serverFirstMessage.nonce().startsWith(clientNonce))
throw new SaslException("Invalid server nonce: does not start with client nonce");
if (serverFirstMessage.iterations() < mechanism.minIterations())
throw new SaslException("Requested iterations " + serverFirstMessage.iterations() + " is less than the minimum " + mechanism.minIterations() + " for " + mechanism);
PasswordCallback passwordCallback = new PasswordCallback("Password:", false);
try {
callbackHandler.handle(new Callback[]{passwordCallback});
} catch (IOException | UnsupportedCallbackException e) {
throw new SaslException("User name could not be obtained", e);
}
this.clientFinalMessage = handleServerFirstMessage(passwordCallback.getPassword());
setState(State.RECEIVE_SERVER_FINAL_MESSAGE);
return clientFinalMessage.toBytes();
case RECEIVE_SERVER_FINAL_MESSAGE:
ServerFinalMessage serverFinalMessage = new ServerFinalMessage(challenge);
if (serverFinalMessage.error() != null)
throw new SaslException("Sasl authentication using " + mechanism + " failed with error: " + serverFinalMessage.error());
handleServerFinalMessage(serverFinalMessage.serverSignature());
setState(State.COMPLETE);
return null;
default:
throw new IllegalSaslStateException("Unexpected challenge in Sasl client state " + state);
}
} catch (SaslException e) {
setState(State.FAILED);
throw e;
}
}
@Override
public boolean isComplete() {
return state == State.COMPLETE;
}
@Override
public byte[] unwrap(byte[] incoming, int offset, int len) throws SaslException {
if (!isComplete())
throw new IllegalStateException("Authentication exchange has not completed");
return Arrays.copyOfRange(incoming, offset, offset + len);
}
@Override
public byte[] wrap(byte[] outgoing, int offset, int len) throws SaslException {
if (!isComplete())
throw new IllegalStateException("Authentication exchange has not completed");
return Arrays.copyOfRange(outgoing, offset, offset + len);
}
@Override
public Object getNegotiatedProperty(String propName) {
if (!isComplete())
throw new IllegalStateException("Authentication exchange has not completed");
return null;
}
@Override
public void dispose() throws SaslException {
}
private void setState(State state) {
log.debug("Setting SASL/{} client state to {}", mechanism, state);
this.state = state;
}
private ClientFinalMessage handleServerFirstMessage(char[] password) throws SaslException {
try {
byte[] passwordBytes = formatter.normalize(new String(password));
this.saltedPassword = formatter.hi(passwordBytes, serverFirstMessage.salt(), serverFirstMessage.iterations());
ClientFinalMessage clientFinalMessage = new ClientFinalMessage("n,,".getBytes(StandardCharsets.UTF_8), serverFirstMessage.nonce());
byte[] clientProof = formatter.clientProof(saltedPassword, clientFirstMessage, serverFirstMessage, clientFinalMessage);
clientFinalMessage.proof(clientProof);
return clientFinalMessage;
} catch (InvalidKeyException e) {
throw new SaslException("Client final message could not be created", e);
}
}
private void handleServerFinalMessage(byte[] signature) throws SaslException {
try {
byte[] serverKey = formatter.serverKey(saltedPassword);
byte[] serverSignature = formatter.serverSignature(serverKey, clientFirstMessage, serverFirstMessage, clientFinalMessage);
if (!Arrays.equals(signature, serverSignature))
throw new SaslException("Invalid server signature in server final message");
} catch (InvalidKeyException e) {
throw new SaslException("Sasl server signature verification failed", e);
}
}
public static class ScramSaslClientFactory implements SaslClientFactory {
@Override
public SaslClient createSaslClient(String[] mechanisms,
String authorizationId,
String protocol,
String serverName,
Map<String, ?> props,
CallbackHandler cbh) throws SaslException {
ScramMechanism mechanism = null;
for (String mech : mechanisms) {
mechanism = ScramMechanism.forMechanismName(mech);
if (mechanism != null)
break;
}
if (mechanism == null)
throw new SaslException(String.format("Requested mechanisms '%s' not supported. Supported mechanisms are '%s'.",
Arrays.asList(mechanisms), ScramMechanism.mechanismNames()));
try {
return new ScramSaslClient(mechanism, cbh);
} catch (NoSuchAlgorithmException e) {
throw new SaslException("Hash algorithm not supported for mechanism " + mechanism, e);
}
}
@Override
public String[] getMechanismNames(Map<String, ?> props) {
Collection<String> mechanisms = ScramMechanism.mechanismNames();
return mechanisms.toArray(new String[mechanisms.size()]);
}
}
}