Spring Security

Available as of Camel 2.3

The camel-spring-security component provides role-based authorization for Camel routes. It leverages the authentication and user services provided by Spring Security (formerly Acegi Security) and adds a declarative, role-based policy system to control whether a route can be executed by a given principal.

If you are not familiar with the Spring Security authentication and authorization system, please review the current reference documentation on the SpringSource web site linked above.

Creating authorization policies

Access to a route is controlled by an instance of a SpringSecurityAuthorizationPolicy object. A policy object contains the name of the Spring Security authority (role) required to run a set of endpoints and references to Spring Security AuthenticationManager and AccessDecisionManager objects used to determine whether the current principal has been assigned that role. Policy objects may be configured as Spring beans or by using an <authorizationPolicy> element in Spring XML.

The <authorizationPolicy> element may contain the following attributes:

NameDefault ValueDescription
idnullThe unique Spring bean identifier which is used to reference the policy in routes (required)
accessnullThe Spring Security authority name that is passed to the access decision manager (required)
authenticationManagerauthenticationManagerThe name of the Spring Security AuthenticationManager object in the context
accessDecisionManageraccessDecisionManagerThe name of the Spring Security AccessDecisionManager object in the context
authenticationAdapterDefaultAuthenticationAdapterCamel 2.4 The name of a camel-spring-security AuthenticationAdapter object in the context that is used to convert a javax.security.auth.Subject into a Spring Security Authentication instance.
useThreadSecurityContexttrueIf a javax.security.auth.Subject cannot be found in the In message header under Exchange.AUTHENTICATION, check the Spring Security SecurityContextHolder for an Authentication object.
alwaysReauthenticatefalseIf set to true, the SpringSecurityAuthorizationPolicy will always call AuthenticationManager.authenticate() each time the policy is accessed.

Controlling access to Camel routes

A Spring Security AuthenticationManager and AccessDecisionManager are required to use this component. Here is an example of how to configure these objects in Spring XML using the Spring Security namespace:

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:spring-security="http://www.springframework.org/schema/security"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
			http://www.springframework.org/schema/beans/spring-beans.xsd
			http://www.springframework.org/schema/security
			http://www.springframework.org/schema/security/spring-security.xsd">

    <bean id="accessDecisionManager" class="org.springframework.security.access.vote.AffirmativeBased">
        <property name="allowIfAllAbstainDecisions" value="true"/>
        <property name="decisionVoters">
            <list>
                <bean class="org.springframework.security.access.vote.RoleVoter"/>
            </list>
        </property>
    </bean>
    
    <spring-security:authentication-manager alias="authenticationManager">
    	<spring-security:authentication-provider user-service-ref="userDetailsService"/>
    </spring-security:authentication-manager>
   
    <spring-security:user-service id="userDetailsService">
        <spring-security:user name="jim" password="jimspassword" authorities="ROLE_USER, ROLE_ADMIN"/>
        <spring-security:user name="bob" password="bobspassword" authorities="ROLE_USER"/>
    </spring-security:user-service>

</beans>

Now that the underlying security objects are set up, we can use them to configure an authorization policy and use that policy to control access to a route:

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:spring-security="http://www.springframework.org/schema/security"
       xsi:schemaLocation="
          http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
          http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
          http://camel.apache.org/schema/spring-security http://camel.apache.org/schema/spring-security/camel-spring-security.xsd
          http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security.xsd">

    <!-- import the spring security configuration  -->
    <import resource="classpath:org/apache/camel/component/spring/security/commonSecurity.xml"/>

    <authorizationPolicy id="admin" access="ROLE_ADMIN"
                         authenticationManager="authenticationManager"
                         accessDecisionManager="accessDecisionManager"
                         xmlns="http://camel.apache.org/schema/spring-security"/>

    <camelContext id="myCamelContext" xmlns="http://camel.apache.org/schema/spring">
        <route>
            <from uri="direct:start"/>
            <!-- The exchange should be authenticated with the role of ADMIN before it is send to mock:endpoint -->
            <policy ref="admin">
                <to uri="mock:end"/>
            </policy>
        </route>
    </camelContext>

</beans>

In this example, the endpoint mock:end will not be executed unless a Spring Security Authentication object that has been or can be authenticated and contains the ROLE_ADMIN authority can be located by the admin SpringSecurityAuthorizationPolicy.

Authentication

The process of obtaining security credentials that are used for authorization is not specified by this component. You can write your own processors or components which get authentication information from the exchange depending on your needs. For example, you might create a processor that gets credentials from an HTTP request header originating in the Jetty component. No matter how the credentials are collected, they need to be placed in the In message or the SecurityContextHolder so the Camel Spring Security component can access them:

import javax.security.auth.Subject;
import org.apache.camel.*;
import org.apache.commons.codec.binary.Base64;
import org.springframework.security.authentication.*;


public class MyAuthService implements Processor {
    public void process(Exchange exchange) throws Exception {
        // get the username and password from the HTTP header
        // http://en.wikipedia.org/wiki/Basic_access_authentication
        String userpass = new String(Base64.decodeBase64(exchange.getIn().getHeader("Authorization", String.class)));
        String[] tokens= userpass.split(":");
        
        // create an Authentication object
        UsernamePasswordAuthenticationToken authToken = new UsernamePasswordAuthenticationToken(tokens[0], tokens[1]);

        // wrap it in a Subject
        Subject subject = new Subject();
        subject.getPrincipals().add(token);

        // place the Subject in the In message
        exchange.getIn().setHeader(Exchange.AUTHENTICATION, subject);

        // you could also do this if useThreadSecurityContext is set to true
        // SecurityContextHolder.getContext().setAuthentication(authToken);
    }
}

The SpringSecurityAuthorizationPolicy will automatically authenticate the Authentication object if necessary.

There are two issues to be aware of when using the SecurityContextHolder instead of or in addition to the Exchange.AUTHENTICATION header. First, the context holder uses a thread-local variable to hold the Authentication object. Any routes that cross thread boundaries, like seda or jms, will lose the Authentication object. Second, the Spring Security system appears to expect that an Authentication object in the context is already authenticated and has roles (see the Technical Overview section 5.3.1 for more details).

The default behavior of camel-spring-security is to look for a Subject in the Exchange.AUTHENTICATION header. This Subject must contain at least one principal, which must be a subclass of org.springframework.security.core.Authentication. You can customize the mapping of Subject to Authentication object by providing an implementation of the org.apache.camel.component.spring.security.AuthenticationAdapter to your <authorizationPolicy> bean. This can be useful if you are working with components that do not use Spring Security but do provide a Subject. At this time, only the CXF component populates the Exchange.AUTHENTICATION header.

Handling authentication and authorization errors

If authentication or authorization fails in the SpringSecurityAuthorizationPolicy, a CamelAuthorizationException will be thrown. This can be handled using Camel's standard exception handling methods, like the Exception Clause. The CamelAuthorizationException will have a reference to the ID of the policy which threw the exception so you can handle errors based on the policy as well as the type of exception:

<onException>
  <exception>org.springframework.security.authentication.AccessDeniedException</exception>
  <choice>
    <when>
      <simple>${exception.policyId} == 'user'</simple>
      <transform>
        <constant>You do not have ROLE_USER access!</constant>
      </transform>
    </when>
    <when>
      <simple>${exception.policyId} == 'admin'</simple>
      <transform>
        <constant>You do not have ROLE_ADMIN access!</constant>
      </transform>
    </when>
  </choice>
</onException>

Dependencies

Maven users will need to add the following dependency to their pom.xml for this component:

 
<dependency> 
  <groupId>org.apache.camel</groupId> 
  <artifactId>camel-spring-security</artifactId> 
  <version>2.4.0</version> 
</dependency>

This dependency will also pull in org.springframework.security:spring-security-core:3.0.3.RELEASE and org.springframework.security:spring-security-config:3.0.3.RELEASE.

See Also
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