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A common base library for Apache Accumulo servers.
There is a newer version: 3.0.0
/*
 * 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.accumulo.server.rpc;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.accumulo.core.client.impl.DelegationTokenImpl;
import org.apache.accumulo.core.client.impl.thrift.SecurityErrorCode;
import org.apache.accumulo.core.client.impl.thrift.ThriftSecurityException;
import org.apache.accumulo.core.client.security.tokens.AuthenticationToken;
import org.apache.accumulo.core.client.security.tokens.KerberosToken;
import org.apache.accumulo.core.conf.AccumuloConfiguration;
import org.apache.accumulo.core.rpc.SaslConnectionParams.SaslMechanism;
import org.apache.accumulo.core.security.thrift.TCredentials;
import org.apache.accumulo.server.security.SystemCredentials.SystemToken;
import org.apache.accumulo.server.security.UserImpersonation;
import org.apache.accumulo.server.security.UserImpersonation.UsersWithHosts;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Extracts the TCredentials object from the RPC argument list and asserts that the Accumulo principal is equal to the Kerberos 'primary' component of the
 * Kerberos principal (e.g. Accumulo principal of "frank" equals "frank" from "frank/hostname@DOMAIN").
 */
public class TCredentialsUpdatingInvocationHandler implements InvocationHandler {
  private static final Logger log = LoggerFactory.getLogger(TCredentialsUpdatingInvocationHandler.class);

  private static final ConcurrentHashMap> TOKEN_CLASS_CACHE = new ConcurrentHashMap<>();
  private final I instance;
  private final UserImpersonation impersonation;

  protected TCredentialsUpdatingInvocationHandler(final I serverInstance, AccumuloConfiguration conf) {
    instance = serverInstance;
    impersonation = new UserImpersonation(conf);
  }

  @Override
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    updateArgs(args);

    return invokeMethod(method, args);
  }

  /**
   * Try to find a TCredentials object in the argument list, and, when the AuthenticationToken is a KerberosToken, set the principal from the SASL server as the
   * TCredentials principal. This ensures that users can't spoof a different principal into the Credentials than what they used to authenticate.
   */
  protected void updateArgs(Object[] args) throws ThriftSecurityException {
    // If we don't have at least two args
    if (args == null || args.length < 2) {
      return;
    }

    TCredentials tcreds = null;
    if (args[0] != null && args[0] instanceof TCredentials) {
      tcreds = (TCredentials) args[0];
    } else if (args[1] != null && args[1] instanceof TCredentials) {
      tcreds = (TCredentials) args[1];
    }

    // If we don't find a tcredentials in the first two positions
    if (null == tcreds) {
      // Not all calls require authentication (e.g. closeMultiScan). We need to let these pass through.
      log.trace("Did not find a TCredentials object in the first two positions of the argument list, not updating principal");
      return;
    }

    Class tokenClass = getTokenClassFromName(tcreds.tokenClassName);

    // The Accumulo principal extracted from the SASL transport
    final String principal = UGIAssumingProcessor.rpcPrincipal();

    // If we authenticated the user over DIGEST-MD5 and they have a DelegationToken, the principals should match
    if (SaslMechanism.DIGEST_MD5 == UGIAssumingProcessor.rpcMechanism() && DelegationTokenImpl.class.isAssignableFrom(tokenClass)) {
      if (!principal.equals(tcreds.principal)) {
        log.warn("{} issued RPC with delegation token over DIGEST-MD5 as the Accumulo principal {}. Disallowing RPC", principal, tcreds.principal);
        throw new ThriftSecurityException("RPC principal did not match provided Accumulo principal", SecurityErrorCode.BAD_CREDENTIALS);
      }
      return;
    }

    // If the authentication token isn't a KerberosToken
    if (!KerberosToken.class.isAssignableFrom(tokenClass) && !SystemToken.class.isAssignableFrom(tokenClass)) {
      // Don't include messages about SystemToken since it's internal
      log.debug("Will not update principal on authentication tokens other than KerberosToken. Received " + tokenClass);
      throw new ThriftSecurityException("Did not receive a valid token", SecurityErrorCode.BAD_CREDENTIALS);
    }

    if (null == principal) {
      log.debug("Found KerberosToken in TCredentials, but did not receive principal from SASL processor");
      throw new ThriftSecurityException("Did not extract principal from Thrift SASL processor", SecurityErrorCode.BAD_CREDENTIALS);
    }

    // The principal from the SASL transport should match what the user requested as their Accumulo principal
    if (!principal.equals(tcreds.principal)) {
      UsersWithHosts usersWithHosts = impersonation.get(principal);
      if (null == usersWithHosts) {
        principalMismatch(principal, tcreds.principal);
      }
      if (!usersWithHosts.getUsers().contains(tcreds.principal)) {
        principalMismatch(principal, tcreds.principal);
      }
      String clientAddr = TServerUtils.clientAddress.get();
      if (!usersWithHosts.getHosts().contains(clientAddr)) {
        final String msg = "Principal in credentials object allowed mismatched Kerberos principals, but not on " + clientAddr;
        log.warn(msg);
        throw new ThriftSecurityException(msg, SecurityErrorCode.BAD_CREDENTIALS);
      }
    }
  }

  protected void principalMismatch(String expected, String actual) throws ThriftSecurityException {
    final String msg = "Principal in credentials object should match kerberos principal. Expected '" + expected + "' but was '" + actual + "'";
    log.warn(msg);
    throw new ThriftSecurityException(msg, SecurityErrorCode.BAD_CREDENTIALS);
  }

  protected Class getTokenClassFromName(String tokenClassName) {
    Class typedClz = TOKEN_CLASS_CACHE.get(tokenClassName);
    if (null == typedClz) {
      Class clz;
      try {
        clz = Class.forName(tokenClassName);
      } catch (ClassNotFoundException e) {
        log.debug("Could not create class from token name: " + tokenClassName, e);
        return null;
      }
      typedClz = clz.asSubclass(AuthenticationToken.class);
    }
    // return the current one and throw away the one we just created if some other thread created it first
    Class current = TOKEN_CLASS_CACHE.putIfAbsent(tokenClassName, typedClz);
    return current != null ? current : typedClz;
  }

  private Object invokeMethod(Method method, Object[] args) throws Throwable {
    try {
      return method.invoke(instance, args);
    } catch (InvocationTargetException ex) {
      throw ex.getCause();
    }
  }

  /**
   * Visibile for testing
   */
  protected ConcurrentHashMap> getTokenCache() {
    return TOKEN_CLASS_CACHE;
  }
}