yasserzamani commented on a change in pull request #426: URL: https://github.com/apache/struts/pull/426#discussion_r455177518
########## File path: core/src/main/java/org/apache/struts2/interceptor/FetchMetadataInterceptor.java ########## @@ -0,0 +1,84 @@ +/* + * 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.struts2.interceptor; + +import static org.apache.struts2.interceptor.ResourceIsolationPolicy.SEC_FETCH_DEST_HEADER; +import static org.apache.struts2.interceptor.ResourceIsolationPolicy.SEC_FETCH_MODE_HEADER; +import static org.apache.struts2.interceptor.ResourceIsolationPolicy.SEC_FETCH_SITE_HEADER; +import static org.apache.struts2.interceptor.ResourceIsolationPolicy.VARY_HEADER; + +import com.opensymphony.xwork2.ActionContext; +import com.opensymphony.xwork2.ActionInvocation; +import com.opensymphony.xwork2.interceptor.AbstractInterceptor; +import com.opensymphony.xwork2.interceptor.PreResultListener; +import com.opensymphony.xwork2.util.TextParseUtil; + +import javax.servlet.http.HttpServletRequest; +import javax.servlet.http.HttpServletResponse; +import java.util.HashSet; +import java.util.Set; + +/** + * Interceptor that implements Fetch Metadata policy on incoming requests used to protect against + * CSRF, XSSI, and cross-origin information leaks. Uses {@link StrutsResourceIsolationPolicy} to + * filter the requests allowed to be processed. + * + * @see <a href="https://web.dev/fetch-metadata/";>https://web.dev/fetch-metadata/</a> + **/ + +public class FetchMetadataInterceptor extends AbstractInterceptor implements PreResultListener { + + private final Set<String> exemptedPaths = new HashSet<String>(); + private final ResourceIsolationPolicy resourceIsolationPolicy = new StrutsResourceIsolationPolicy(); + private static final String VARY_HEADER_VALUE = String.format("%s,%s,%s", SEC_FETCH_DEST_HEADER, SEC_FETCH_SITE_HEADER, SEC_FETCH_MODE_HEADER); + private static final String SC_FORBIDDEN = String.valueOf(HttpServletResponse.SC_FORBIDDEN); + + public void setExemptedPaths(String paths){ + this.exemptedPaths.addAll(TextParseUtil.commaDelimitedStringToSet(paths)); + } + + @Override + public void beforeResult(ActionInvocation invocation, String resultCode) { + // Add Vary headers + HttpServletResponse response = invocation.getInvocationContext().getServletResponse(); + response.setHeader(VARY_HEADER, VARY_HEADER_VALUE); + } + + @Override + public String intercept(ActionInvocation invocation) throws Exception { + ActionContext context = invocation.getInvocationContext(); + HttpServletRequest request = context.getServletRequest(); + + // Adds listener that operates between interceptor and result rendering to set Vary headers + invocation.addPreResultListener(this); + + // Apply exemptions: paths/endpoints meant to be served cross-origin + if (exemptedPaths.contains(request.getContextPath())) { + return invocation.invoke(); + } + + // Check if request is allowed + if (resourceIsolationPolicy.isRequestAllowed(request)) { + return invocation.invoke(); + } + + beforeResult(invocation, SC_FORBIDDEN); Review comment: Doesn't work without this line? -- it's already registered as a pre-result. ########## File path: core/src/main/java/org/apache/struts2/interceptor/StrutsResourceIsolationPolicy.java ########## @@ -0,0 +1,63 @@ +/* + * 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.struts2.interceptor; + +import org.apache.logging.log4j.util.Strings; + +import javax.servlet.http.HttpServletRequest; + +/** + * + * Default resource isolation policy used in {@link FetchMetadataInterceptor} that + * implements the {@link ResourceIsolationPolicy} interface. This default policy is based on + * <a href="https://web.dev/fetch-metadata/";>https://web.dev/fetch-metadata/</a>. + * + * @see <a href="https://web.dev/fetch-metadata/";>https://web.dev/fetch-metadata/</a> + **/ + +public final class StrutsResourceIsolationPolicy implements ResourceIsolationPolicy { + + @Override + public boolean isRequestAllowed(HttpServletRequest request) { + String site = request.getHeader(SEC_FETCH_SITE_HEADER); + + // Allow requests from browsers which don't send Fetch Metadata + if (Strings.isEmpty((site))){ Review comment: nitpick: waste parenteses. Additionally you might use `org.apache.commons.lang3.StringUtils.isEmpty/isBlank` instead. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
