org.apache.kafka.common.security.plain.internals.PlainSaslServer Maven / Gradle / Ivy
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/*
* 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.plain.internals;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
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.sasl.Sasl;
import javax.security.sasl.SaslException;
import javax.security.sasl.SaslServer;
import javax.security.sasl.SaslServerFactory;
import org.apache.kafka.common.errors.SaslAuthenticationException;
import org.apache.kafka.common.security.plain.PlainAuthenticateCallback;
/**
* Simple SaslServer implementation for SASL/PLAIN. In order to make this implementation
* fully pluggable, authentication of username/password is fully contained within the
* server implementation.
*
* Valid users with passwords are specified in the Jaas configuration file. Each user
* is specified with user_ as key and as value. This is consistent
* with Zookeeper Digest-MD5 implementation.
*
* To avoid storing clear passwords on disk or to integrate with external authentication
* servers in production systems, this module can be replaced with a different implementation.
*
*/
public class PlainSaslServer implements SaslServer {
public static final String PLAIN_MECHANISM = "PLAIN";
private final CallbackHandler callbackHandler;
private boolean complete;
private String authorizationId;
public PlainSaslServer(CallbackHandler callbackHandler) {
this.callbackHandler = callbackHandler;
}
/**
* @throws SaslAuthenticationException if username/password combination is invalid or if the requested
* authorization id is not the same as username.
*
* Note: This method may throw {@link SaslAuthenticationException} to provide custom error messages
* to clients. But care should be taken to avoid including any information in the exception message that
* should not be leaked to unauthenticated clients. It may be safer to throw {@link SaslException} in
* some cases so that a standard error message is returned to clients.
*
*/
@Override
public byte[] evaluateResponse(byte[] responseBytes) throws SaslAuthenticationException {
/*
* Message format (from https://tools.ietf.org/html/rfc4616):
*
* message = [authzid] UTF8NUL authcid UTF8NUL passwd
* authcid = 1*SAFE ; MUST accept up to 255 octets
* authzid = 1*SAFE ; MUST accept up to 255 octets
* passwd = 1*SAFE ; MUST accept up to 255 octets
* UTF8NUL = %x00 ; UTF-8 encoded NUL character
*
* SAFE = UTF1 / UTF2 / UTF3 / UTF4
* ;; any UTF-8 encoded Unicode character except NUL
*/
String response = new String(responseBytes, StandardCharsets.UTF_8);
List tokens = extractTokens(response);
String authorizationIdFromClient = tokens.get(0);
String username = tokens.get(1);
String password = tokens.get(2);
if (username.isEmpty()) {
throw new SaslAuthenticationException("Authentication failed: username not specified");
}
if (password.isEmpty()) {
throw new SaslAuthenticationException("Authentication failed: password not specified");
}
NameCallback nameCallback = new NameCallback("username", username);
PlainAuthenticateCallback authenticateCallback = new PlainAuthenticateCallback(password.toCharArray());
try {
callbackHandler.handle(new Callback[]{nameCallback, authenticateCallback});
} catch (Throwable e) {
throw new SaslAuthenticationException("Authentication failed: credentials for user could not be verified", e);
}
if (!authenticateCallback.authenticated())
throw new SaslAuthenticationException("Authentication failed: Invalid username or password");
if (!authorizationIdFromClient.isEmpty() && !authorizationIdFromClient.equals(username))
throw new SaslAuthenticationException("Authentication failed: Client requested an authorization id that is different from username");
this.authorizationId = username;
complete = true;
return new byte[0];
}
private List extractTokens(String string) {
List tokens = new ArrayList<>();
int startIndex = 0;
for (int i = 0; i < 4; ++i) {
int endIndex = string.indexOf("\u0000", startIndex);
if (endIndex == -1) {
tokens.add(string.substring(startIndex));
break;
}
tokens.add(string.substring(startIndex, endIndex));
startIndex = endIndex + 1;
}
if (tokens.size() != 3)
throw new SaslAuthenticationException("Invalid SASL/PLAIN response: expected 3 tokens, got " +
tokens.size());
return tokens;
}
@Override
public String getAuthorizationID() {
if (!complete)
throw new IllegalStateException("Authentication exchange has not completed");
return authorizationId;
}
@Override
public String getMechanismName() {
return PLAIN_MECHANISM;
}
@Override
public Object getNegotiatedProperty(String propName) {
if (!complete)
throw new IllegalStateException("Authentication exchange has not completed");
return null;
}
@Override
public boolean isComplete() {
return complete;
}
@Override
public byte[] unwrap(byte[] incoming, int offset, int len) {
if (!complete)
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) {
if (!complete)
throw new IllegalStateException("Authentication exchange has not completed");
return Arrays.copyOfRange(outgoing, offset, offset + len);
}
@Override
public void dispose() {
}
public static class PlainSaslServerFactory implements SaslServerFactory {
@Override
public SaslServer createSaslServer(String mechanism, String protocol, String serverName, Map props, CallbackHandler cbh)
throws SaslException {
if (!PLAIN_MECHANISM.equals(mechanism))
throw new SaslException(String.format("Mechanism \'%s\' is not supported. Only PLAIN is supported.", mechanism));
return new PlainSaslServer(cbh);
}
@Override
public String[] getMechanismNames(Map props) {
if (props == null) return new String[]{PLAIN_MECHANISM};
String noPlainText = (String) props.get(Sasl.POLICY_NOPLAINTEXT);
if ("true".equals(noPlainText))
return new String[]{};
else
return new String[]{PLAIN_MECHANISM};
}
}
}