Java tutorial
/* * Copyright 2002-2013 the original author or authors. * * 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 * * https://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.springframework.security.web.authentication.session; import java.util.Enumeration; import java.util.HashMap; import java.util.Map; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; /** * Uses {@code HttpServletRequest.invalidate()} to protect against session fixation * attacks. * <p> * Creates a new session for the newly authenticated user if they already have a session * (as a defence against session-fixation protection attacks), and copies their session * attributes across to the new session. The copying of the attributes can be disabled by * setting {@code migrateSessionAttributes} to {@code false} (note that even in this case, * internal Spring Security attributes will still be migrated to the new session). * <p> * This approach will only be effective if your servlet container always assigns a new * session Id when a session is invalidated and a new session created by calling * {@link HttpServletRequest#getSession()}. * <p> * <h3>Issues with {@code HttpSessionBindingListener}</h3> * <p> * The migration of existing attributes to the newly-created session may cause problems if * any of the objects implement the {@code HttpSessionBindingListener} interface in a way * which makes assumptions about the life-cycle of the object. An example is the use of * Spring session-scoped beans, where the initial removal of the bean from the session * will cause the {@code DisposableBean} interface to be invoked, in the assumption that * the bean is no longer required. * <p> * We'd recommend that you take account of this when designing your application and do not * store attributes which may not function correctly when they are removed and then placed * back in the session. Alternatively, you should customize the * {@code SessionAuthenticationStrategy} to deal with the issue in an application-specific * way. * * @author Luke Taylor * @since 3.0 */ public class SessionFixationProtectionStrategy extends AbstractSessionFixationProtectionStrategy { /** * Indicates that the session attributes of an existing session should be migrated to * the new session. Defaults to <code>true</code>. */ boolean migrateSessionAttributes = true; /** * Called to extract the existing attributes from the session, prior to invalidating * it. If {@code migrateAttributes} is set to {@code false}, only Spring Security * attributes will be retained. All application attributes will be discarded. * <p> * You can override this method to control exactly what is transferred to the new * session. * * @param session the session from which the attributes should be extracted * @return the map of session attributes which should be transferred to the new * session */ protected Map<String, Object> extractAttributes(HttpSession session) { return createMigratedAttributeMap(session); } @Override final HttpSession applySessionFixation(HttpServletRequest request) { HttpSession session = request.getSession(); String originalSessionId = session.getId(); if (logger.isDebugEnabled()) { logger.debug("Invalidating session with Id '" + originalSessionId + "' " + (migrateSessionAttributes ? "and" : "without") + " migrating attributes."); } Map<String, Object> attributesToMigrate = extractAttributes(session); session.invalidate(); session = request.getSession(true); // we now have a new session if (logger.isDebugEnabled()) { logger.debug("Started new session: " + session.getId()); } transferAttributes(attributesToMigrate, session); return session; } /** * @param attributes the attributes which were extracted from the original session by * {@code extractAttributes} * @param newSession the newly created session */ void transferAttributes(Map<String, Object> attributes, HttpSession newSession) { if (attributes != null) { for (Map.Entry<String, Object> entry : attributes.entrySet()) { newSession.setAttribute(entry.getKey(), entry.getValue()); } } } @SuppressWarnings("unchecked") private HashMap<String, Object> createMigratedAttributeMap(HttpSession session) { HashMap<String, Object> attributesToMigrate = new HashMap<>(); Enumeration enumer = session.getAttributeNames(); while (enumer.hasMoreElements()) { String key = (String) enumer.nextElement(); if (!migrateSessionAttributes && !key.startsWith("SPRING_SECURITY_")) { // Only retain Spring Security attributes continue; } attributesToMigrate.put(key, session.getAttribute(key)); } return attributesToMigrate; } /** * Defines whether attributes should be migrated to a new session or not. Has no * effect if you override the {@code extractAttributes} method. * <p> * Attributes used by Spring Security (to store cached requests, for example) will * still be retained by default, even if you set this value to {@code false}. * * @param migrateSessionAttributes whether the attributes from the session should be * transferred to the new, authenticated session. */ public void setMigrateSessionAttributes(boolean migrateSessionAttributes) { this.migrateSessionAttributes = migrateSessionAttributes; } }