Apache ESME [Retired]

Thursday April 07, 2011

Container-Managed Authentication with Apache ESME: Part 1

Part 1: Performing authentication with plaintext/xml user-role mapping

This blog was written by our new committer Vladimir Ivanov who implemented a feature that users have been wanting for a long time. 

Introduction

Apache ESME currently supports two different authentication schemes: when user credentials are stored in the database and via OpenID.  Corporate users, however, might be interested in container-managed authentication (CMA) — because this scheme supports integration with enterprise services such as LDAP and Single Sign-On. In the first part of this blog,  I'll explain how ESME-based applications can use CMA and how to configure two popular web servers- Apache Tomcat and Jetty - with simple user-role mapping. In the second part, I'll describe LDAP integration to perform CMA and how get additional user attributes via the Lift LDAP API.

ContainerManagedAuthModule: The necessary code changes

A new authentication module ContainerManagedAuthModule was introduced to hook into the container-managed authentication process. First of all, it was registered along with the other authentication modules:

Boot.scala

    UserAuth.register(UserPwdAuthModule)

    UserAuth.register(OpenIDAuthModule) 

    UserAuth.register(ContainerManagedAuthModule)

UserAuth.scala

All authentication modules should extend the AuthModule trait:

object ContainerManagedAuthModule extends AuthModule

Currently, the list with security role (group) names is also defined in the source code:

  val rolesToCheck = List(

    "esme-users"

  )

It is also possible to get the list of roles from some external source, for example, from a property file or a LDAP.

The method moduleName defines the name for the new auth module. This value acts as a discriminator and will be stored in the DB:

  def moduleName: String = "cm"

After the container finishes the authentication and authorization phases, it is  neccessary to hook into the normal user processing to save the user data. This task is performed in the performInit method:

def performInit(): Unit = {

CMA must be applied to a specific URL, for example /cm/login, so it is necessary to append a partial function to LiftRules.dispatch to perform the neccessary operations:

    LiftRules.dispatch.append {

      case Req("cm" :: "login" :: Nil, _, _) =>  {

        val from = "/"

Note: The majority of necessary steps to further utilize this new auth method have already been desribed in the Lift Wiki.

In short, it is neccessary to unwrap the javax.servlet.http.HttpServletRequest object to get the username and role names. If a user has one of the specified roles, the module should attempt to find an existing user with the same nickname which previously has logged in via this module. If such a user hasn't been found, a new User is created.  The last step is to save the userId in the HTTP session via User.logUserIn method call.

        S.request match {

          case Full(req) => {

            val httpRequest: HTTPRequest = req.request

            val hrs = httpRequest.asInstanceOf[HTTPRequestServlet]

            val hsr: HttpServletRequest = hrs.req

            val username : String = hsr.getRemoteUser

            if(username!=null){

              val currentRoles = rolesToCheck.filter(hsr.isUserInRole(_))

              if(currentRoles.size == 0) {

                info("No roles have been found")

                S.error(S.?("base_user_err_unknown_creds"))

              } else {

                currentRoles.map(cr => {

                (for {

                    user <- UserAuth.find(By(UserAuth.authKey, username),

                                          By(UserAuth.authType, moduleName)).flatMap(_.user.obj) or

                    User.find(By(User.nickname, username))

                  } yield user) match {

                    case Full(user) => {

                      logInUser(user)

                    }

                    case _ => {

                      val usr = User.createAndPopulate.nickname(username).saveMe

                      //find and save additional attributes in LDAP if it's enabled

              ...

                      }

                      UserAuth.create.authType(moduleName).user(usr).authKey(username).save

                      logInUser(usr)

                    }

                  }

                })

              }

    }

Configuration

Now it's time to set-up the configuration for the CMA. All configuration settings for a Java EE web application (ESME is based on the Lift web framework, so it's packaged as a WAR file), including security settings, are defined in the web.xml file:

web.xml

For this example, we will use form-based authentication:

<login-config>

      <auth-method>FORM</auth-method>

      <realm-name>ESMERealm</realm-name>

Next, the login and error pages are specified.

        <form-login-config>

            <form-login-page>/cm_login.jsp</form-login-page>

            <form-error-page>/cm_error.jsp</form-error-page>

        </form-login-config>

    </login-config>

Then, the security-role name, which any authenticated user must have for successful authorization, is defined:

    <!-- Security roles referenced by this web application -->

    <security-role>

      <description>An authenticated ESME user</description>

      <role-name>esme-users</role-name>

    </security-role>

And finally it is necessary to configure the mapping between the security role and the URL which is associated with the new authentication module:

  <!-- Secured resources -->

    <security-constraint>

      <web-resource-collection>

        <web-resource-name>ForceLogin</web-resource-name>

        <description>Secured page for forcing the container to request login</description>

        <url-pattern>/cm/login</url-pattern>

      </web-resource-collection>

      <auth-constraint>

        <role-name>esme-users</role-name>

      </auth-constraint>

    </security-constraint>

The login page contains a form with specific action attributes and two input fields:

cm_login.jsp

<html>

    <head>

      <title>Login</title>

    </head>

    <body id="cm_login">

        <form method="POST" action="j_security_check">

          Username: <input type="text" name="j_username"/><br>

          Password: <input type="password" name="j_password"/><br>

          <input type="submit"/>

        </form>

    </body>

</html>

Let's move on to the web server configuration for the next steps. We must define the users for our web application as well as mapping between these users and the security role that is specified in the web.xml file. I'll show how to configure simple user-role mapping for two popular web servers — Jetty and Tomcat.

Jetty

The HashUserRealm implementation is used to specify the user-role mapping in the properties file for Jetty. The maven-jetty-plugin has been already included in the Maven project file pom.xml for the ESME application, so it is possible to configure Jetty in the plugin configuration section:

pom.xml

            <plugin>

                <groupId>org.mortbay.jetty</groupId>

                <artifactId>maven-jetty-plugin</artifactId>

                <configuration>

                    <contextPath>/</contextPath>

                    <scanIntervalSeconds>0</scanIntervalSeconds>

                    <userRealms>

                        <userRealm implementation="org.mortbay.jetty.security.HashUserRealm">

                            <name>ESMERealm</name>

                            <config>jetty-login.properties</config>

                        </userRealm>

                    </userRealms>

                </configuration>

            </plugin>

The format for this property file has the following form: username: password [,rolename ...].

An example is shown below:

jetty-login.properties

cmuser: cmuser, esme-users

That's it. Now Jetty is configured for CMA. Execute mvn clean jetty-run command to start Jetty and type http://localhost:8080/cm/login URL in your browser. You should see the form containing the username and password fields. Now try to log in with the user with the id cmuser.

Tomcat

The configuration of Tomcat web server is very similar to that of Jetty, except that the user-role mapping is specified in a XML file.  The MemoryUserDatabaseFactory implementation is used to define the mapping file.  The corresponding realm UserDatabaseRealm is also specified in the server.xml configuration file:

server.xml

  <GlobalNamingResources>

    <!-- Editable user database that can also be used by

         UserDatabaseRealm to authenticate users

    -->

    <Resource name="UserDatabase" auth="Container"

              type="org.apache.catalina.UserDatabase"

              description="User database that can be updated and saved"

              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"

              pathname="conf/tomcat-users.xml" />

  </GlobalNamingResources>

...

      <Realm className="org.apache.catalina.realm.UserDatabaseRealm"

             resourceName="UserDatabase"/>

Below is an example of the user-role mapping definition in the tomcat-users.xml file which is usually located in the  tomcat/conf directory.

tomcat-users.xml

<tomcat-users>

  <role rolename="esme-users"/>

  <user name="cmuser" password="cmuser" roles="esme-users"/>

</tomcat-users>

Now it's neccessary to package the WAR file with the mvn clean package command and deploy it to Tomcat either via maven plugin or in Tomcat's administrative console. Then proceed to the following URL:

http://localhost:8080/your_web_context/cm/login

The login form should be displayed.

Conclusion

In this part of the blog, I've covered the new authentication module, application and server configuration and simple user-role mapping. In the next part, I'll show how to configure Tomcat to use LDAP for CMA and get additional attributes for the authenticated user.

Links

1. Lift Wiki - How to use Container Managed Security : http://www.assembla.com/wiki/show/liftweb/How_to_use_Container_Managed_Security

2. Jetty HashUserRealm: http://jetty.codehaus.org/jetty/jetty-6/apidocs/org/mortbay/jetty/security/HashUserRealm.html

3. Tomcat Realms: http://tomcat.apache.org/tomcat-6.0-doc/realm-howto.html

4. Java EE 5 Tutorial – Securing Web Applications: http://download.oracle.com/javaee/5/tutorial/doc/bncas.html

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