我们需要实现的类有以下几个:
- LoginModule
- Provider(client和server)
- SaslClientFactory
- SaslClient
- SaslServerFactory
- SaslServer
LoginModule
要先实现LoginModule。这个LoginModule中在客户端需要初始化SaslClientProvider,服务端需要初始化SaslServerProvider,为了方便,这里直接初始化两个Provider。如果客户端是给外部用户使用的话,为了安全,只需要初始化SaslClientProvider即可。
import javax.security.auth.Subject;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.login.LoginException;
import javax.security.auth.spi.LoginModule;
import java.util.Map;
public class ABCLoginModule implements LoginModule {
private static final String USERNAME = "username";
private static final String PASSWORD = "password";
static {
ABCSaslClientProvider.initialize();
ABCSaslServerProvider.initialize();
}
@Override
public void initialize(Subject subject, CallbackHandler callbackHandler, Map<String, ?> sharedState, Map<String, ?> optiABC) {
String accessKey = (String) optiABC.get(USERNAME);
if (accessKey != null)
subject.getPublicCredentials().add(accessKey);
String secretKey = (String) optiABC.get(PASSWORD);
if (secretKey != null)
subject.getPrivateCredentials().add(secretKey);
}
@Override
public boolean login() throws LoginException {
return true;
}
@Override
public boolean logout() throws LoginException {
return true;
}
@Override
public boolean commit() throws LoginException {
return true;
}
@Override
public boolean abort() throws LoginException {
return false;
}
}
Provider
而后我们分别实现两个Provider,Client和Server,代码太简单了就不多赘述了。
public class ABCSaslClientProvider extends Provider {
private static final long serialVersionUID = 1L;
protected ABCSaslClientProvider() {
super("Simple SASL/ABC Client Provider", 1.0, "Simple SASL/ABC Client Provider for Kafka");
super.put("SaslClientFactory." + ABCSaslClient.ABC_MECHANISM, ABCSaslClientFactory.class.getName());
}
public static void initialize() {
Security.addProvider(new ABCSaslClientProvider());
}
}
public class ABCSaslServerProvider extends Provider {
private static final long serialVersionUID = 1L;
protected ABCSaslServerProvider() {
super("Simple SASL/ABC Server Provider", 1.0, "Simple SASL/ABC Server Provider for Kafka");
super.put("SaslServerFactory." + ABCSaslServer.ABC_MECHANISM, ABCSaslServerFactory.class.getName());
}
public static void initialize() {
Security.addProvider(new ABCSaslServerProvider());
}
}
SaslClientFactory
SaslClientFactory中需要做的事有以下几个:
- 判断客户端的安全机制是否是ABC,只支持ABC的安全机制
- 从callbackHandler对象中取出用户密码
- 使用用户密码来构造出SaslClient
public class ABCSaslClientFactory implements SaslClientFactory{
private static final String[] myMechs = new String[]{ABCSaslClient.ABC_MECHANISM};
@Override
public SaslClient createSaslClient(String[] mechanisms, String authorizationId, String protocol, String serverName,
Map<String, ?> props, CallbackHandler cbh) throws SaslException {
if (mechanisms.length != 1 || !mechanisms[0].equals(ABCSaslClient.ABC_MECHANISM)) {
throw new SaslException("Mechanism ERROR, only support mechanism:" + ABCSaslClient.ABC_MECHANISM);
}
String mech = ABCSaslClient.ABC_MECHANISM;
String username = null;
String password = null;
if(cbh == null) {
throw new SaslException("Callback handler to get username/password required");
} else {
try {
String namePrompt = mech + " authentication id: ";
String passwordPrompt = mech + " password: ";
NameCallback nameCallBack = new NameCallback(namePrompt);
PasswordCallback passwdCallBack = new PasswordCallback(passwordPrompt, false);
cbh.handle(new Callback[]{nameCallBack, passwdCallBack});
char[] pwdBytes = passwdCallBack.getPassword();
password = null;
if(pwdBytes != null) {
password = new String(pwdBytes);
passwdCallBack.clearPassword();
}
username = nameCallBack.getName();
} catch (IOException var11) {
throw new SaslException("Cannot get password", var11);
} catch (UnsupportedCallbackException var12) {
throw new SaslException("Cannot get userid/password", var12);
}
}
return new SaslClient(username,password);
}
@Override
public String[] getMechanismNames(Map<String, ?> props) {
return myMechs;
}
}
SaslClient
SaslClient中需要实现以下几个功能:
- 保存username和password
- 保存Sasl客户端的校验状态(complete)
- 判断服务端的报文,是需要发送校验数据还是校验通过
- 构造加密报文
本例中的加密报文构造方法是
- 先构造出一个byte数组:格式为[0,username.getBytes(),0,password.getBytes()]
- 将构造出的byte数组加密(方法略),可以直接使用SHA-256不可逆加密,得到一个新的byte数组encrypt。
- 将用户名放在encrypt前面变成最终发送给服务端的报文,格式为[0, username.getBytes(), 0, encrypt]
public class ABCSaslClient implements SaslClient{
public static final String ABC_MECHANISM="ABC";
private String username;
private String password;
private boolean complete=false;
private byte SEP=0;
public ABCSaslClient(String username, String password) throws SaslException {
if (username == null || password == null) {
throw new SaslException("username/password must be specified");
}
this.username=username;
this.password=password;
}
@Override
public String getMechanismName() {
return ABC_MECHANISM;
}
// hasInitialResponse()返回false表示INITIAL发送一个空包给服务端,返回true则表示会发送一个自定义的包,详见SaslClientAuthenticator.createSaslToken
@Override
public boolean hasInitialResponse() {
return false;
}
@Override
public byte[] evaluateChallenge(byte[] challenge) throws SaslException {
if(this.complete) {
throw new IllegalStateException("Authentication already completed");
} else {
//收到服务端返回的空包,表示通过校验,complete置为true并退出
if (challenge.length == 0) {
this.complete = true;
return null;
}
/**
* 如果收到的不是空包,表示可以构造校验报文了,这里有个小trick,可以在服务端生成随机数或时间戳,作为server token发送到客户端
* 客户端可以将server token中的数据放到加密串中,增强报文的安全性。
*/
byte[] data = ABCUtil.join(SEP, username.getBytes("UTF-8"),password.getBytes("UTF-8"));
byte[] encrypt = ABCUtil.encrypt(data);
byte[] response = ABCUtil.join(SEP, username.getBytes("UTF-8"), encrypt);
return response;
}
}
@Override
public boolean isComplete() {
return this.complete;
}
@Override
public byte[] unwrap(byte[] incoming, int offset, int len) throws SaslException {
if(this.complete) {
throw new SaslException("PLAIN supports neither integrity nor privacy");
} else {
throw new IllegalStateException("PLAIN authentication not completed");
}
}
@Override
public byte[] wrap(byte[] outgoing, int offset, int len) throws SaslException {
if(this.complete) {
throw new SaslException("PLAIN supports neither integrity nor privacy");
} else {
throw new IllegalStateException("PLAIN authentication not completed");
}
}
@Override
public Object getNegotiatedProperty(String propName) {
if(this.complete) {
return propName.equals("javax.security.sasl.qop")?"auth":null;
} else {
throw new IllegalStateException("PLAIN authentication not completed");
}
}
@Override
public void dispose() throws SaslException {
password=null;
}
}
至此,完成客户端的部分。下面构造服务端的SaslServer。
SaslServerFactory
SaslServerFactory和Client很类似,需要实现的功能有:
- 判断client的安全机制是否是ABC
- 构造出SaslServer
代码比SaslClientFactory更简单一些
public class ABCSaslServerFactory implements SaslServerFactory{
private static final String[] myMechs = new String[]{ABCSaslServer.ABC_MECHANISM};
@Override
public SaslServer createSaslServer(String mechanism, String protocol, String serverName, Map<String, ?> props,
CallbackHandler cbh) throws SaslException {
if (!mechanism.equals(ABCSaslClient.ABC_MECHANISM)) {
throw new SaslException("Mechanism ERROR, only support mechanism:" + ABCSaslServer.ABC_MECHANISM);
}
return new ABCSaslServer(cbh);
}
@Override
public String[] getMechanismNames(Map<String, ?> props) {
return myMechs;
}
}
SaslServer
SaslServer需要处理两种报文,需要实现的功能和SaslClient类似:
- 记录校验状态(complete)
- 收到client端INITIAL阶段送的报文,处理并返回server token
- 收到client端的校验数据,校验信息
- 校验通过返回空包
这里有两个点需要注意,一个是complete一定要有,还有就是authorizationID一定要有,因为都是在Kafka中会被调用的方法。
public class ABCSaslServer implements SaslServer {
public static final String ABC_MECHANISM = "ABC";
private boolean complete = false;
private String authID;
public ABCSaslServer(CallbackHandler cbh) throws SaslException {
}
@Override
public String getMechanismName() {
return ABC_MECHANISM;
}
@Override
public boolean isComplete() {
return this.complete;
}
@Override
public Object getNegotiatedProperty(String propName) {
if (!complete)
throw new IllegalStateException("Authentication exchange has not completed");
return null;
}
@Override
public byte[] unwrap(byte[] incoming, int offset, int len) throws SaslException {
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) throws SaslException {
if (!complete)
throw new IllegalStateException("Authentication exchange has not completed");
return Arrays.copyOfRange(outgoing, offset, offset + len);
}
@Override
public void dispose() throws SaslException {
}
@Override
public byte[] evaluateResponse(byte[] response) throws SaslException {
//收到客户端INITIAL阶段发送的空包,返回一个server token
if (response.length == 0) {
return "ABC by MisterCH".getBytes("UTF-8");
}
String[] tokens;
try {
tokens = new String(response, "UTF-8").split("\u0000");
} catch (UnsupportedEncodingException e) {
throw new SaslException("UTF-8 encoding not supported", e);
}
if (tokens.length != 3)
throw new SaslException("Invalid SASL/ABC response: expected 3 tokens, got " + tokens.length);
// 从包中提取出用户名和加密串
authID = tokens[0];
String username = tokens[1];
String encrypt = tokens[2];
if (username.isEmpty()) {
throw new SaslException("Authentication failed: username not specified");
}
if (authID.isEmpty())
authID = username;
// 在服务端拿到用户对应的密码
String password = ABCUtil.getPassword(username);
byte[] data = ABCUtil.join(SEP, username.getBytes("UTF-8"),password.getBytes("UTF-8"));
byte[] expectedToken = ABCUtil.encrypt(data);
// 比对服务端加密的串和客户端加密的串是否一致(对称加密),一致则通过校验
if (!ABCUtils.isEqual(encrypt, expectedToken);) {
throw new SaslException("Authentication failed: Invalid username or password");
}
complete = true;
return new byte[0];
}
@Override
public String getAuthorizationID() {
return this.authID;
}
}
配置修改
写完这些代码,打包成jar文件,而后放在kafka的libs目录下。服务端需要配置jaas文件作为jaas的入口,并修改server.properties。
KafkaServer{
com.company.MisterCH.ABCLoginModule required
username="test"
password="test"
user_ch="chsss";
};
修改Kafka的启动脚本不赘述,server.properties中需要修改几个地方
#broker内部通信使用PLAIN机制9092端口,外部通信使用SASL_PLAINTEXT的9093端口
listeners=PLAINTEXT://hostname:9093,SASL_PALINTEXT://hostname:9092
sasl.mechanism=ABC
security.protocol=SASL_PLAINTEXT
客户端可以不用配置jaas文件,直接在producer.properties或consumer.properties中修改如下配置
security.protocol=SASL_PLAINTEXT
sasl.mechanism=ABC
sasl.jaas.config=com.company.MisterCH.ABCLoginModule required \
ch \
chsss \;