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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 freemarker.ext.beans;
import java.lang.reflect.Method;
import java.util.Collection;
import freemarker.template.ObjectWrapper;
/**
* Whitelist-based member access policy, that is, only members that are matched by the listing will be exposed.
* Note that {@link BeansWrapper} and its subclasses doesn't discover all members on the first place, and the
* {@link MemberAccessPolicy} just removes from that set of members, never adds to it.
*
* The whitelist content is usually application specific, and can be significant work to put together, but it's the
* only way you can achieve any practical safety when you don't fully trust the users who can edit templates.
*
*
See more about the rules at {@link MemberSelectorListMemberAccessPolicy}.
* {@link TemplateAccessible} annotation may be used to add members to the whitelist.
*
*
Of course, this only can deal with the {@link ObjectWrapper} aspect of safety; please check the Manual to see what
* else is needed. Also, since this is related to security, read the documentation of {@link MemberAccessPolicy}, to
* know about the pitfalls and edge cases related to {@link MemberAccessPolicy}-es in general.
*
* @since 2.3.30
*/
public class WhitelistMemberAccessPolicy extends MemberSelectorListMemberAccessPolicy {
private static final Method TO_STRING_METHOD;
static {
try {
TO_STRING_METHOD = Object.class.getMethod("toString");
} catch (NoSuchMethodException e) {
throw new IllegalStateException(e);
}
}
private final boolean toStringAlwaysExposed;
/**
* @param memberSelectors
* List of member selectors; see {@link MemberSelectorListMemberAccessPolicy} class-level documentation for
* more.
*/
public WhitelistMemberAccessPolicy(Collection memberSelectors) {
super(memberSelectors, ListType.WHITELIST, TemplateAccessible.class);
toStringAlwaysExposed = forClass(Object.class).isMethodExposed(TO_STRING_METHOD);
}
@Override
public boolean isToStringAlwaysExposed() {
return toStringAlwaysExposed;
}
}