108 lines
3.7 KiB
Java
108 lines
3.7 KiB
Java
/*
|
|
* Copyright (C) 2022 The Android Open Source Project
|
|
*
|
|
* Licensed 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 dalvik.system;
|
|
|
|
import libcore.util.NonNull;
|
|
|
|
import java.util.Objects;
|
|
import java.util.zip.ZipException;
|
|
|
|
/**
|
|
* Enables validation of zip file entry paths to prevent exploitation of the path traversal
|
|
* vulnerability, e.g. zip path entries containing ".." or "/". For more details, read
|
|
* <a href="https://developer.android.com/topic/security/risks/zip-path-traversal">this</a>.
|
|
* <p>
|
|
* The default implementation accepts all zip file entry paths without raising any exceptions.
|
|
* <p>
|
|
* For custom validation rules, the core functionality should be implemented in a {@link Callback}
|
|
* interface and that instance should be set in {@link #setCallback(Callback)}.
|
|
* <p>
|
|
* Existing validation could be set to a default one by calling {@link #clearCallback()}.
|
|
*/
|
|
public final class ZipPathValidator {
|
|
|
|
/**
|
|
* Default implementation of the {@link Callback} interface which accepts all paths.
|
|
*
|
|
* @hide
|
|
*/
|
|
public static final Callback DEFAULT = new Callback() {};
|
|
|
|
private static volatile Callback sInstance = DEFAULT;
|
|
|
|
/**
|
|
* Clears the current validation mechanism by setting the current callback instance to a default
|
|
* validation.
|
|
*/
|
|
public static void clearCallback() {
|
|
sInstance = DEFAULT;
|
|
}
|
|
|
|
/**
|
|
* Sets the current callback implementation for zip paths.
|
|
* <p>
|
|
* The provided callback should not perform IO or any blocking operations, but only perform path
|
|
* validation. A typical implementation will validate String entries in a single pass and throw
|
|
* a {@link ZipException} if the path contains potentially hazardous components such as "..".
|
|
*
|
|
* @param callback An instance of {@link Callback}'s implementation.
|
|
*/
|
|
public static void setCallback(@NonNull Callback callback) {
|
|
sInstance = Objects.requireNonNull(callback);
|
|
}
|
|
|
|
/**
|
|
* Retrieves the current validator set by {@link #setCallback(Callback)}.
|
|
*
|
|
* @return Current callback.
|
|
*
|
|
* @hide
|
|
*/
|
|
public static @NonNull Callback getInstance() {
|
|
return sInstance;
|
|
}
|
|
|
|
/**
|
|
* Returns true if the current validator is the default implementation {@link DEFAULT},
|
|
* otherwise false.
|
|
*
|
|
* @hide
|
|
*/
|
|
public static boolean isClear() {
|
|
return sInstance.equals(DEFAULT);
|
|
}
|
|
|
|
/**
|
|
* Interface that defines the core validation mechanism when accessing zip file entry paths.
|
|
*/
|
|
public interface Callback {
|
|
/**
|
|
* Called to check the validity of the path of a zip entry. The default implementation
|
|
* accepts all paths without raising any exceptions.
|
|
* <p>
|
|
* This method will be called by {@link java.util.zip.ZipInputStream#getNextEntry} or
|
|
* {@link java.util.zip.ZipFile#ZipFile(String)}.
|
|
*
|
|
* @param path The name of the zip entry.
|
|
* @throws ZipException If the zip entry is invalid depending on the implementation.
|
|
*/
|
|
default void onZipEntryAccess(@NonNull String path) throws ZipException {}
|
|
}
|
|
|
|
private ZipPathValidator() {}
|
|
}
|