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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;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.StringTokenizer;
import java.util.concurrent.TimeUnit;
import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.thirdparty.com.google.common.base.Joiner;
import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.util.Shell;
import org.apache.hadoop.util.Shell.ExitCodeException;
import org.apache.hadoop.util.Shell.ShellCommandExecutor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A simple shell-based implementation of {@link GroupMappingServiceProvider}
* that exec's the groups shell command to fetch the group
* memberships of a given user.
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Evolving
public class ShellBasedUnixGroupsMapping extends Configured
implements GroupMappingServiceProvider {
@VisibleForTesting
protected static final Logger LOG =
LoggerFactory.getLogger(ShellBasedUnixGroupsMapping.class);
private long timeout = CommonConfigurationKeys.
HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_DEFAULT;
private static final List EMPTY_GROUPS = new LinkedList<>();
@Override
public void setConf(Configuration conf) {
super.setConf(conf);
if (conf != null) {
timeout = conf.getTimeDuration(
CommonConfigurationKeys.
HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_KEY,
CommonConfigurationKeys.
HADOOP_SECURITY_GROUP_SHELL_COMMAND_TIMEOUT_DEFAULT,
TimeUnit.MILLISECONDS);
}
}
@SuppressWarnings("serial")
private static class PartialGroupNameException extends IOException {
public PartialGroupNameException(String message) {
super(message);
}
public PartialGroupNameException(String message, Throwable err) {
super(message, err);
}
@Override
public String toString() {
final StringBuilder sb =
new StringBuilder("PartialGroupNameException ");
sb.append(super.getMessage());
return sb.toString();
}
}
/**
* Returns list of groups for a user
*
* @param userName get groups for this user
* @return list of groups for a given user
*/
@Override
public List getGroups(String userName) throws IOException {
return getUnixGroups(userName);
}
/**
* Caches groups, no need to do that for this provider
*/
@Override
public void cacheGroupsRefresh() throws IOException {
// does nothing in this provider of user to groups mapping
}
/**
* Adds groups to cache, no need to do that for this provider
*
* @param groups unused
*/
@Override
public void cacheGroupsAdd(List groups) throws IOException {
// does nothing in this provider of user to groups mapping
}
/**
* Create a ShellCommandExecutor object using the user's name.
*
* @param userName user's name
* @return a ShellCommandExecutor object
*/
protected ShellCommandExecutor createGroupExecutor(String userName) {
return new ShellCommandExecutor(
getGroupsForUserCommand(userName), null, null, timeout);
}
/**
* Returns just the shell command to be used to fetch a user's groups list.
* This is mainly separate to make some tests easier.
* @param userName The username that needs to be passed into the command built
* @return An appropriate shell command with arguments
*/
protected String[] getGroupsForUserCommand(String userName) {
return Shell.getGroupsForUserCommand(userName);
}
/**
* Create a ShellCommandExecutor object for fetch a user's group id list.
*
* @param userName the user's name
* @return a ShellCommandExecutor object
*/
protected ShellCommandExecutor createGroupIDExecutor(String userName) {
return new ShellCommandExecutor(
getGroupsIDForUserCommand(userName), null, null, timeout);
}
/**
* Returns just the shell command to be used to fetch a user's group IDs list.
* This is mainly separate to make some tests easier.
* @param userName The username that needs to be passed into the command built
* @return An appropriate shell command with arguments
*/
protected String[] getGroupsIDForUserCommand(String userName) {
return Shell.getGroupsIDForUserCommand(userName);
}
/**
* Check if the executor had a timeout and logs the event.
* @param executor to check
* @param user user to log
* @return true if timeout has occurred
*/
private boolean handleExecutorTimeout(
ShellCommandExecutor executor,
String user) {
// If its a shell executor timeout, indicate so in the message
// but treat the result as empty instead of throwing it up,
// similar to how partial resolution failures are handled above
if (executor.isTimedOut()) {
LOG.warn(
"Unable to return groups for user '{}' as shell group lookup " +
"command '{}' ran longer than the configured timeout limit of " +
"{} seconds.",
user,
Joiner.on(' ').join(executor.getExecString()),
timeout
);
return true;
}
return false;
}
/**
* Get the current user's group list from Unix by running the command 'groups'
* NOTE. For non-existing user it will return EMPTY list.
*
* @param user get groups for this user
* @return the groups list that the user belongs to. The primary
* group is returned first.
* @throws IOException if encounter any error when running the command
*/
private List getUnixGroups(String user) throws IOException {
ShellCommandExecutor executor = createGroupExecutor(user);
List groups;
try {
executor.execute();
groups = resolveFullGroupNames(executor.getOutput());
} catch (ExitCodeException e) {
if (handleExecutorTimeout(executor, user)) {
return EMPTY_GROUPS;
} else {
try {
groups = resolvePartialGroupNames(user, e.getMessage(),
executor.getOutput());
} catch (PartialGroupNameException pge) {
LOG.warn("unable to return groups for user {}", user, pge);
return EMPTY_GROUPS;
}
}
} catch (IOException ioe) {
if (handleExecutorTimeout(executor, user)) {
return EMPTY_GROUPS;
} else {
// If its not an executor timeout, we should let the caller handle it
throw ioe;
}
}
// remove duplicated primary group
if (!Shell.WINDOWS) {
for (int i = 1; i < groups.size(); i++) {
if (groups.get(i).equals(groups.get(0))) {
groups.remove(i);
break;
}
}
}
return groups;
}
/**
* Attempt to parse group names given that some names are not resolvable.
* Use the group id list to identify those that are not resolved.
*
* @param groupNames a string representing a list of group names
* @param groupIDs a string representing a list of group ids
* @return a linked list of group names
* @throws PartialGroupNameException
*/
private List parsePartialGroupNames(String groupNames,
String groupIDs) throws PartialGroupNameException {
StringTokenizer nameTokenizer =
new StringTokenizer(groupNames, Shell.TOKEN_SEPARATOR_REGEX);
StringTokenizer idTokenizer =
new StringTokenizer(groupIDs, Shell.TOKEN_SEPARATOR_REGEX);
List groups = new LinkedList();
while (nameTokenizer.hasMoreTokens()) {
// check for unresolvable group names.
if (!idTokenizer.hasMoreTokens()) {
throw new PartialGroupNameException("Number of group names and ids do"
+ " not match. group name =" + groupNames + ", group id = " + groupIDs);
}
String groupName = nameTokenizer.nextToken();
String groupID = idTokenizer.nextToken();
if (!StringUtils.isNumeric(groupName) ||
!groupName.equals(groupID)) {
// if the group name is non-numeric, it is resolved.
// if the group name is numeric, but is not the same as group id,
// regard it as a group name.
// if unfortunately, some group names are not resolvable, and
// the group name is the same as the group id, regard it as not
// resolved.
groups.add(groupName);
}
}
return groups;
}
/**
* Attempt to partially resolve group names.
*
* @param userName the user's name
* @param errMessage error message from the shell command
* @param groupNames the incomplete list of group names
* @return a list of resolved group names
* @throws PartialGroupNameException if the resolution fails or times out
*/
private List resolvePartialGroupNames(String userName,
String errMessage, String groupNames) throws PartialGroupNameException {
// Exception may indicate that some group names are not resolvable.
// Shell-based implementation should tolerate unresolvable groups names,
// and return resolvable ones, similar to what JNI-based implementation
// does.
if (Shell.WINDOWS) {
throw new PartialGroupNameException("Does not support partial group"
+ " name resolution on Windows. " + errMessage);
}
if (groupNames.isEmpty()) {
throw new PartialGroupNameException("The user name '" + userName
+ "' is not found. " + errMessage);
} else {
LOG.warn("Some group names for '{}' are not resolvable. {}",
userName, errMessage);
// attempt to partially resolve group names
ShellCommandExecutor partialResolver = createGroupIDExecutor(userName);
try {
partialResolver.execute();
return parsePartialGroupNames(
groupNames, partialResolver.getOutput());
} catch (ExitCodeException ece) {
// If exception is thrown trying to get group id list,
// something is terribly wrong, so give up.
throw new PartialGroupNameException(
"failed to get group id list for user '" + userName + "'", ece);
} catch (IOException ioe) {
String message =
"Can't execute the shell command to " +
"get the list of group id for user '" + userName + "'";
if (partialResolver.isTimedOut()) {
message +=
" because of the command taking longer than " +
"the configured timeout: " + timeout + " seconds";
}
throw new PartialGroupNameException(message, ioe);
}
}
}
/**
* Split group names into a linked list.
*
* @param groupNames a string representing the user's group names
* @return a linked list of group names
*/
@VisibleForTesting
protected List resolveFullGroupNames(String groupNames) {
StringTokenizer tokenizer =
new StringTokenizer(groupNames, Shell.TOKEN_SEPARATOR_REGEX);
List groups = new LinkedList();
while (tokenizer.hasMoreTokens()) {
groups.add(tokenizer.nextToken());
}
return groups;
}
}
