org.apache.hadoop.security.token.SecretManager.java Source code

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Here is the source code for org.apache.hadoop.security.token.SecretManager.java

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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.hadoop.security.token;

import java.io.IOException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.ipc.RetriableException;
import org.apache.hadoop.ipc.StandbyException;

/**
 * The server-side secret manager for each token type.
 * @param <T> The type of the token identifier
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class SecretManager<T extends TokenIdentifier> {
    /**
     * The token was invalid and the message explains why.
     */
    @SuppressWarnings("serial")
    @InterfaceStability.Evolving
    public static class InvalidToken extends IOException {
        public InvalidToken(String msg) {
            super(msg);
        }
    }

    /**
     * Create the password for the given identifier.
     * identifier may be modified inside this method.
     * @param identifier the identifier to use
     * @return the new password
     */
    protected abstract byte[] createPassword(T identifier);

    /**
     * Retrieve the password for the given token identifier. Should check the date
     * or registry to make sure the token hasn't expired or been revoked. Returns 
     * the relevant password.
     * @param identifier the identifier to validate
     * @return the password to use
     * @throws InvalidToken the token was invalid
     */
    public abstract byte[] retrievePassword(T identifier) throws InvalidToken;

    /**
     * The same functionality with {@link #retrievePassword}, except that this 
     * method can throw a {@link RetriableException} or a {@link StandbyException}
     * to indicate that client can retry/failover the same operation because of 
     * temporary issue on the server side.
     * 
     * @param identifier the identifier to validate
     * @return the password to use
     * @throws InvalidToken the token was invalid
     * @throws StandbyException the server is in standby state, the client can
     *         try other servers
     * @throws RetriableException the token was invalid, and the server thinks 
     *         this may be a temporary issue and suggests the client to retry
     * @throws IOException to allow future exceptions to be added without breaking
     *         compatibility        
     */
    public byte[] retriableRetrievePassword(T identifier)
            throws InvalidToken, StandbyException, RetriableException, IOException {
        return retrievePassword(identifier);
    }

    /**
     * Create an empty token identifier.
     * @return the newly created empty token identifier
     */
    public abstract T createIdentifier();

    /**
     * No-op if the secret manager is available for reading tokens, throw a
     * StandbyException otherwise.
     * 
     * @throws StandbyException if the secret manager is not available to read
     *         tokens
     */
    public void checkAvailableForRead() throws StandbyException {
        // Default to being available for read.
    }

    /**
     * The name of the hashing algorithm.
     */
    private static final String DEFAULT_HMAC_ALGORITHM = "HmacSHA1";

    /**
     * The length of the random keys to use.
     */
    private static final int KEY_LENGTH = 64;

    /**
     * A thread local store for the Macs.
     */
    private static final ThreadLocal<Mac> threadLocalMac = new ThreadLocal<Mac>() {
        @Override
        protected Mac initialValue() {
            try {
                return Mac.getInstance(DEFAULT_HMAC_ALGORITHM);
            } catch (NoSuchAlgorithmException nsa) {
                throw new IllegalArgumentException("Can't find " + DEFAULT_HMAC_ALGORITHM + " algorithm.");
            }
        }
    };

    /**
     * Key generator to use.
     */
    private final KeyGenerator keyGen;
    {
        try {
            keyGen = KeyGenerator.getInstance(DEFAULT_HMAC_ALGORITHM);
            keyGen.init(KEY_LENGTH);
        } catch (NoSuchAlgorithmException nsa) {
            throw new IllegalArgumentException("Can't find " + DEFAULT_HMAC_ALGORITHM + " algorithm.");
        }
    }

    /**
     * Generate a new random secret key.
     * @return the new key
     */
    protected SecretKey generateSecret() {
        SecretKey key;
        synchronized (keyGen) {
            key = keyGen.generateKey();
        }
        return key;
    }

    /**
     * Compute HMAC of the identifier using the secret key and return the 
     * output as password
     * @param identifier the bytes of the identifier
     * @param key the secret key
     * @return the bytes of the generated password
     */
    protected static byte[] createPassword(byte[] identifier, SecretKey key) {
        Mac mac = threadLocalMac.get();
        try {
            mac.init(key);
        } catch (InvalidKeyException ike) {
            throw new IllegalArgumentException("Invalid key to HMAC computation", ike);
        }
        return mac.doFinal(identifier);
    }

    /**
     * Convert the byte[] to a secret key
     * @param key the byte[] to create a secret key from
     * @return the secret key
     */
    protected static SecretKey createSecretKey(byte[] key) {
        return new SecretKeySpec(key, DEFAULT_HMAC_ALGORITHM);
    }
}