/**
* 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.hdfs.server.namenode;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.Stack;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.UnresolvedLinkException;
import org.apache.hadoop.fs.permission.FsAction;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot;
import org.apache.hadoop.security.AccessControlException;
import org.apache.hadoop.security.UserGroupInformation;
/**
* Class that helps in checking file system permission.
* The state of this class need not be synchronized as it has data structures that
* are read-only.
*
* Some of the helper methods are gaurded by {@link FSNamesystem#readLock()}.
*/
class FSPermissionChecker {
static final Log LOG = LogFactory.getLog(UserGroupInformation.class);
/** @return a string for throwing {@link AccessControlException} */
private static String toAccessControlString(INode inode) {
return "\"" + inode.getFullPathName() + "\":"
+ inode.getUserName() + ":" + inode.getGroupName()
+ ":" + (inode.isDirectory()? "d": "-") + inode.getFsPermission();
}
private final UserGroupInformation ugi;
private final String user;
/** A set with group namess. Not synchronized since it is unmodifiable */
private final Set<String> groups;
private final boolean isSuper;
FSPermissionChecker(String fsOwner, String supergroup,
UserGroupInformation callerUgi) {
ugi = callerUgi;
HashSet<String> s = new HashSet<String>(Arrays.asList(ugi.getGroupNames()));
groups = Collections.unmodifiableSet(s);
user = ugi.getShortUserName();
isSuper = user.equals(fsOwner) || groups.contains(supergroup);
}
/**
* Check if the callers group contains the required values.
* @param group group to check
*/
public boolean containsGroup(String group) {return groups.contains(group);}
public String getUser() {
return user;
}
public boolean isSuperUser() {
return isSuper;
}
/**
* Verify if the caller has the required permission. This will result into
* an exception if the caller is not allowed to access the resource.
*/
public void checkSuperuserPrivilege()
throws AccessControlException {
if (!isSuper) {
throw new AccessControlException("Access denied for user "
+ user + ". Superuser privilege is required");
}
}
/**
* Check whether current user have permissions to access the path.
* Traverse is always checked.
*
* Parent path means the parent directory for the path.
* Ancestor path means the last (the closest) existing ancestor directory
* of the path.
* Note that if the parent path exists,
* then the parent path and the ancestor path are the same.
*
* For example, suppose the path is "/foo/bar/baz".
* No matter baz is a file or a directory,
* the parent path is "/foo/bar".
* If bar exists, then the ancestor path is also "/foo/bar".
* If bar does not exist and foo exists,
* then the ancestor path is "/foo".
* Further, if both foo and bar do not exist,
* then the ancestor path is "/".
*
* @param doCheckOwner Require user to be the owner of the path?
* @param ancestorAccess The access required by the ancestor of the path.
* @param parentAccess The access required by the parent of the path.
* @param access The access required by the path.
* @param subAccess If path is a directory,
* it is the access required of the path and all the sub-directories.
* If path is not a directory, there is no effect.
* @param resolveLink whether to resolve the final path component if it is
* a symlink
* @throws AccessControlException
* @throws UnresolvedLinkException
*
* Guarded by {@link FSNamesystem#readLock()}
* Caller of this method must hold that lock.
*/
void checkPermission(String path, INodeDirectory root, boolean doCheckOwner,
FsAction ancestorAccess, FsAction parentAccess, FsAction access,
FsAction subAccess, boolean resolveLink)
throws AccessControlException, UnresolvedLinkException {
if (LOG.isDebugEnabled()) {
LOG.debug("ACCESS CHECK: " + this
+ ", doCheckOwner=" + doCheckOwner
+ ", ancestorAccess=" + ancestorAccess
+ ", parentAccess=" + parentAccess
+ ", access=" + access
+ ", subAccess=" + subAccess
+ ", resolveLink=" + resolveLink);
}
// check if (parentAccess != null) && file exists, then check sb
// If resolveLink, the check is performed on the link target.
final INodesInPath inodesInPath = root.getINodesInPath(path, resolveLink);
final Snapshot snapshot = inodesInPath.getPathSnapshot();
final INode[] inodes = inodesInPath.getINodes();
int ancestorIndex = inodes.length - 2;
for(; ancestorIndex >= 0 && inodes[ancestorIndex] == null;
ancestorIndex--);
checkTraverse(inodes, ancestorIndex, snapshot);
final INode last = inodes[inodes.length - 1];
if (parentAccess != null && parentAccess.implies(FsAction.WRITE)
&& inodes.length > 1 && last != null) {
checkStickyBit(inodes[inodes.length - 2], last, snapshot);
}
if (ancestorAccess != null && inodes.length > 1) {
check(inodes, ancestorIndex, snapshot, ancestorAccess);
}
if (parentAccess != null && inodes.length > 1) {
check(inodes, inodes.length - 2, snapshot, parentAccess);
}
if (access != null) {
check(last, snapshot, access);
}
if (subAccess != null) {
checkSubAccess(last, snapshot, subAccess);
}
if (doCheckOwner) {
checkOwner(last, snapshot);
}
}
/** Guarded by {@link FSNamesystem#readLock()} */
private void checkOwner(INode inode, Snapshot snapshot
) throws AccessControlException {
if (inode != null && user.equals(inode.getUserName(snapshot))) {
return;
}
throw new AccessControlException("Permission denied");
}
/** Guarded by {@link FSNamesystem#readLock()} */
private void checkTraverse(INode[] inodes, int last, Snapshot snapshot
) throws AccessControlException {
for(int j = 0; j <= last; j++) {
check(inodes[j], snapshot, FsAction.EXECUTE);
}
}
/** Guarded by {@link FSNamesystem#readLock()} */
private void checkSubAccess(INode inode, Snapshot snapshot, FsAction access
) throws AccessControlException {
if (inode == null || !inode.isDirectory()) {
return;
}
Stack<INodeDirectory> directories = new Stack<INodeDirectory>();
for(directories.push(inode.asDirectory()); !directories.isEmpty(); ) {
INodeDirectory d = directories.pop();
check(d, snapshot, access);
for(INode child : d.getChildrenList(snapshot)) {
if (child.isDirectory()) {
directories.push(child.asDirectory());
}
}
}
}
/** Guarded by {@link FSNamesystem#readLock()} */
private void check(INode[] inodes, int i, Snapshot snapshot, FsAction access
) throws AccessControlException {
check(i >= 0? inodes[i]: null, snapshot, access);
}
/** Guarded by {@link FSNamesystem#readLock()} */
private void check(INode inode, Snapshot snapshot, FsAction access
) throws AccessControlException {
if (inode == null) {
return;
}
FsPermission mode = inode.getFsPermission(snapshot);
if (user.equals(inode.getUserName(snapshot))) { //user class
if (mode.getUserAction().implies(access)) { return; }
}
else if (groups.contains(inode.getGroupName(snapshot))) { //group class
if (mode.getGroupAction().implies(access)) { return; }
}
else { //other class
if (mode.getOtherAction().implies(access)) { return; }
}
throw new AccessControlException("Permission denied: user=" + user
+ ", access=" + access + ", inode=" + toAccessControlString(inode));
}
/** Guarded by {@link FSNamesystem#readLock()} */
private void checkStickyBit(INode parent, INode inode, Snapshot snapshot
) throws AccessControlException {
if(!parent.getFsPermission(snapshot).getStickyBit()) {
return;
}
// If this user is the directory owner, return
if(parent.getUserName(snapshot).equals(user)) {
return;
}
// if this user is the file owner, return
if(inode.getUserName(snapshot).equals(user)) {
return;
}
throw new AccessControlException("Permission denied by sticky bit setting:" +
" user=" + user + ", inode=" + inode);
}
}