View Javadoc

    1   /*
    2    * Copyright 2008 University Corporation for Advanced Internet Development, Inc.
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    * http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16
    17  package edu.internet2.middleware.shibboleth.idp.session;
    18
    19  import java.io.IOException;
    20  import java.security.GeneralSecurityException;
    21  import java.security.MessageDigest;
    22  import java.util.Arrays;
    23
    24  import javax.servlet.Filter;
    25  import javax.servlet.FilterChain;
    26  import javax.servlet.FilterConfig;
    27  import javax.servlet.ServletException;
    28  import javax.servlet.ServletRequest;
    29  import javax.servlet.ServletResponse;
    30  import javax.servlet.http.Cookie;
    31  import javax.servlet.http.HttpServletRequest;
    32
    33  import org.joda.time.DateTime;
    34  import org.opensaml.ws.transport.http.HTTPTransportUtils;
    35  import org.opensaml.xml.util.Base64;
    36  import org.opensaml.xml.util.DatatypeHelper;
    37  import org.slf4j.Logger;
    38  import org.slf4j.LoggerFactory;
    39  import org.slf4j.MDC;
    40
    41  import edu.internet2.middleware.shibboleth.common.session.SessionManager;
    42  import edu.internet2.middleware.shibboleth.idp.authn.AuthenticationEngine;
    43
    44  /**
    45   * A filter that adds the current users {@link Session} the request, if the user has a session.
    46   */
    47  public class IdPSessionFilter implements Filter {
    48
    49      /** Class Logger. */
    50      private final Logger log = LoggerFactory.getLogger(IdPSessionFilter.class);
    51
    52      /** Whether the client must always come back from the same address. */
    53      private boolean consistentAddress;
    54
    55      /** IdP session manager. */
    56      private SessionManager<Session> sessionManager;
    57
    58      /** {@inheritDoc} */
    59      public void destroy() {
    60
    61      }
    62
    63      /** {@inheritDoc} */
    64      public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException,
    65              ServletException {
    66          HttpServletRequest httpRequest = (HttpServletRequest) request;
    67
    68          MDC.put("JSESSIONID", httpRequest.getSession().getId());
    69          MDC.put("clientIP", httpRequest.getRemoteAddr());
    70
    71          Cookie sessionCookie = getIdPSessionCookie(httpRequest);
    72          Session idpSession = getUserSession(sessionCookie, httpRequest);
    73          if (idpSession != null) {
    74              log.trace("Updating IdP session activity time and adding session object to the request");
    75              idpSession.setLastActivityInstant(new DateTime());
    76              MDC.put("idpSessionId", idpSession.getSessionID());
    77              httpRequest.setAttribute(Session.HTTP_SESSION_BINDING_ATTRIBUTE, idpSession);
    78          }
    79
    80          filterChain.doFilter(request, response);
    81      }
    82
    83      /** {@inheritDoc} */
    84      public void init(FilterConfig filterConfig) throws ServletException {
    85          String sessionManagerId = filterConfig.getInitParameter("sessionManagedId");
    86          if (DatatypeHelper.isEmpty(sessionManagerId)) {
    87              sessionManagerId = "shibboleth.SessionManager";
    88          }
    89
    90          sessionManager = (SessionManager<Session>) filterConfig.getServletContext().getAttribute(sessionManagerId);
    91
    92          String consistentAddressParam = filterConfig.getInitParameter("ensureConsistentClientAddress");
    93          if (DatatypeHelper.isEmpty(consistentAddressParam)) {
    94              consistentAddress = true;
    95          } else {
    96              consistentAddress = Boolean.parseBoolean(consistentAddressParam);
    97          }
    98      }
    99
    100     /**
    101      * Gets the IdP session cookie from the current request, if the user currently has a session.
    102      *
    103      * @param httpRequest current HTTP request
    104      *
    105      * @return the user's current IdP session cookie, if they have a current session, otherwise null
    106      */
    107     protected Cookie getIdPSessionCookie(HttpServletRequest httpRequest) {
    108         log.trace("Attempting to retrieve IdP session cookie.");
    109         Cookie[] requestCookies = httpRequest.getCookies();
    110
    111         if (requestCookies != null) {
    112             for (Cookie requestCookie : requestCookies) {
    113                 if (DatatypeHelper.safeEquals(requestCookie.getName(), AuthenticationEngine.IDP_SESSION_COOKIE_NAME)) {
    114                     log.trace("Found IdP session cookie.");
    115                     return requestCookie;
    116                 }
    117             }
    118         }
    119
    120         return null;
    121     }
    122
    123     /**
    124      * Gets the user session associated with a session cookie.
    125      *
    126      * @param sessionCookie the session cookie
    127      * @param httpRequest the current HTTP request
    128      *
    129      * @return the session associated with the cookie or null if there is no currently assoicated session
    130      */
    131     protected Session getUserSession(Cookie sessionCookie, HttpServletRequest httpRequest) {
    132         if (sessionCookie == null || DatatypeHelper.isEmpty(sessionCookie.getValue())) {
    133             return null;
    134         }
    135
    136         // index 0: remote address
    137         // index 1: session ID
    138         // index 2: Base64(HMAC(index 0 + index 1))
    139         String cookieValue = HTTPTransportUtils.urlDecode(sessionCookie.getValue());
    140         String[] valueComponents = cookieValue.split("\\|");
    141         if (valueComponents.length != 3) {
    142             log.warn("IdP session cookie has an improperly formated value: {}", cookieValue);
    143             return null;
    144         }
    145
    146         byte[] remoteAddressBytes = Base64.decode(valueComponents[0]);
    147         byte[] sessionIdBytes = Base64.decode(valueComponents[1]);
    148         byte[] signatureBytes = Base64.decode(valueComponents[2]);
    149
    150         String sessionId = new String(sessionIdBytes);
    151         Session userSession = sessionManager.getSession(sessionId);
    152
    153         if (userSession != null) {
    154             if (isCookieValid(httpRequest, remoteAddressBytes, sessionIdBytes, signatureBytes, userSession
    155                     .getSessionSecret())) {
    156                 return userSession;
    157             }
    158         } else {
    159             log.debug("No session associated with session ID {} - session must have timed out", valueComponents[1]);
    160         }
    161         return null;
    162     }
    163
    164     /**
    165      * Validates the session cookie. This validates that the cookie came from the same IP address to which it was given,
    166      * if consistent address checking is enabled, and that cookie data hasn't been changed.
    167      *
    168      * @param httpRequest incoming HTTP request
    169      * @param remoteAddressBytes remote address from the cookie value
    170      * @param sessionIdBytes session ID from the cookie value
    171      * @param signatureBytes signature from the cookie value
    172      * @param sessionSecret secrete associated with the user's session
    173      *
    174      * @return true if the information in the cookie is valid, false if not
    175      */
    176     protected boolean isCookieValid(HttpServletRequest httpRequest, byte[] remoteAddressBytes, byte[] sessionIdBytes,
    177             byte[] signatureBytes, byte[] sessionSecret) {
    178         if (consistentAddress) {
    179             String remoteAddress = new String(remoteAddressBytes);
    180             if (!httpRequest.getRemoteAddr().equals(remoteAddress)) {
    181                 log.error("Client sent a cookie from address {} but the cookie was issued to address {}", httpRequest
    182                         .getRemoteAddr(), remoteAddress);
    183                 return false;
    184             }
    185         }
    186
    187         try {
    188             MessageDigest digester = MessageDigest.getInstance("SHA");
    189             digester.update(sessionSecret);
    190             digester.update(remoteAddressBytes);
    191             digester.update(sessionIdBytes);
    192             if (!Arrays.equals(digester.digest(), signatureBytes)) {
    193                 log.error("Session cookie has been tampered with, its signature no longer matches expected value");
    194                 return false;
    195             }
    196         } catch (GeneralSecurityException e) {
    197             log.error("Unable to compute signature over session cookie material", e);
    198         }
    199
    200         return true;
    201     }
    202 }