eXtensible Access Control Markup Language (XACML) based authorization allows you to have an extremely flexible way of defining the rules of accessing resources based on the user, the user's role, the environment, time and date, etc. The Entitlement Mediator intercepts requests and evaluates the actions performed by a user against an XACML policy. Policies based on XACML 2.0 and 3.0 are supported. WSO2 Identity Server can be used as the XACML Policy Decision Point (PDP) where the policy is set, and the ESB profile of WSO2 EI serves as the XACML Policy Enforcement Point (PEP) where the policy is enforced.
When you add the Entitlement mediator to a sequence, the Entitlement mediator node appears as follows with four sub elements. These sub elements are used to define a mediation sequence to be applied based on the entitlement result.
The following are descriptions for the four sub elements of the Entitlement mediator.
|OnAccept||The sequence to execute when the result returned by the Entitlement mediator is |
|OnReject||The sequence to execute when the result returned by the Entitlement mediator is |
|Obligations||The sequence to execute when the XACML response contains an obligation statement. When this response is received, the Entitlement mediator clones the current message context, creates a new message context, adds the obligation statement to the SOAP body and then executes the sequence. Since the Obligations sequence is executed synchronously, the Entitlement mediator waits for a response. If the sequence returns a |
|Advice||The sequence to execute when the XACML response contains an advice statement. When this response is received, the Entitlement mediator clones the current message context, creates a new message context, adds the advice statement to the SOAP body and then executes the sequence. Since the Advice sequence is executed asynchronously, the Entitlement mediator does not wait for a response.|
The Entitlement mediator configuration screen appears below the tree as shown below.
The parameters available for configuring the Entitlement mediator are as follows.
|Entitlement Server||Server URL of the WSO2 Identity Server that acts as the PDP (e.g.,).|
|User Name||This user should have permissions to log in and manage configurations in the WSO2 Identity Server.|
|Password||The password of the username entered in the User Name parameter.|
|Entitlement Callback Handler|
The handler that should be used to get the subject (user name) for the XACML request.
You need to secure the proxy service, which uses the Entitlement mediator using one of the following methods and select the Entitlement Callback Handler based on the method you used.
You can also set properties that control how the subject is retrieved; see Advanced Callback Properties.
|Entitlement Service Client|
The method of communication to use between the PEP and the PDP. For SOAP, choose whether to use Basic Authentication (available with WSO2 Identify Server 4.0.0 and later) OR the AuthenticationAdmin service, which authenticates with the Entitlement service in Identity Server 3.2.3 and earlier. Thrift uses its own authentication service over TCP. WS-XACML uses Basic Authentication.
The XAMCL standard refrains from specifying which method should be used to communicate from the PEP to the PDP, and many vendors have implemented a proprietary approach. There is a standard called “Web Services Profile of XACML (WS-XACML) Version 1.0″, but it has not been widely adopted because of its bias toward SOAP and the performance implications from XML signatures. However, the benefit of adopting a standard is the elimination of vendor locking, because it will allow your current PEP to work even if you move to a PDP from another vendor (as long as the new PDP also supports this standard). Otherwise you may need to modify your existing PEP to adopt to the new PDP. WSO2 Identity Server has its proprietary SOAP API, Thrift API, and basic support for WS-XACML.
|Thrift Host||The host used to establish a Thrift connection with the Entitlement service when the Entitlement Service Client is set to Thrift.|
|Thrift Port||The port used to establish a Thrift connection with the Entitlement service when the Entitlement Service Client is set to Thrift. The default port is 10500.|
You will now define the sequences you want to run for the entitlement results.
- If you want to specify an existing sequence for a result, click Referring Sequence for that result and select the sequence from the registry.
- If you want to define the sequence in the tree, leave In-Lined Sequence selected.
- Click Update.
- In the tree, click the first result node for which you want to define the sequence, and then add the appropriate mediators to create the sequence. Repeat for each result node.
You can also configure the Mediator using XML. Click switch to source view in the Mediator window.
In the following example, the WSO2 Identity Server (with log in URLis see to authenticate the user invoking the secured backend service.
If the authorization test performed on a request sent to this URL fails, the Fault mediator converts the request into a fault message giving
Unauthorized as the reason for the request to be rejected and
XACML Authorization Failed as the detail. Then the Respond mediator sends the converted message back to the client.
If the user is successfully authenticated, the request is sent using the Send Mediator to the endpoint with the