Today, enterprise applications seek ways of enforcing security that allows the right people to access the right resources with restrictions enforced by enterprise policies. Identity and entitlement management systems, as a whole, attempt to address these security considerations. These systems help enterprise architects and developers in their application requirement implementations and try to significantly ease the burden of security-related implementations. These identity and entitlement management systems are governed by industry standard specifications, hence supporting security requirements for heterogeneous applications becomes easy.
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Click here for more information on Access control. |
This topic consists of the following sections:
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Types of access control
The following table describes the various types of access control.
| Access Control Type | Description |
|---|---|
Access Control Lists | Access control lists are the oldest and most basic form of access control. This type was primarily adopted for use in operating systems. This maintains a set of users and operations that can be performed on a resource as a mapping. This is easy to implement due to the use of maps. However, this is not scalable for larger user bases and can become difficult to manage. |
Role-based Access Control | Role-based Access Control (RBAC) is an approach used to restrict access to authorized users based on their role. This is a static permission model which provides access control. It is used by the majority of enterprises with more than 500 users. This access control type is used when all users are categorized into different roles. The roles define the resources that can be accessed by users assigned to that role. This type of access control reduces management overhead. These users and roles can also be externalized using user stores. These roles need to be managed carefully. There can be instances where a user is assigned to multiple roles. This is a subset of ABAC. Static permissions for roles can be given by updating permission tree in WSO2 Identity Server. Click here for information on Configuring roles and permissions. |
Attribute-based Access Control | Attribute-based access control (ABAC) defines a new access control paradigm whereby access rights are granted to users through the use of policies that combine attributes together. Here, authorization happens based on attributes. This access control type addresses the limitations of role-based access control to provide a more fine-grained approach. This can be based on the attributes of the user, the environment, or even the resource itself. This is more flexible when compared with the role-based approach. There is no need to know the user prior to granting access. |
Policy-based Access Control | This type of access control addresses the requirement to have a more uniform access control mechanism. This helps larger enterprises to have uniform access control for the large amount of organizational units. This is helpful when carrying out security audits. This is the most complex form of access control. This involves specifying policies unambiguously using XACML and using authorized attribute sources in the enterprise. Here Policy Based Access Control(PBAC) (also called Rule-based access control) is an extension of ABAC where attributes are used in writing policies. |
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Introducing XACML
XACML (eXtensible Access Control Markup Language) is an XML-based language for access control that has been standardized by the Technical Committee of the OASIS consortium. XACML is popular as a fine grain authorization method among the community. However, there are aspects of XACML that surpasses other policy standards by being a fine-grained authorization mechanism.
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<?xml version="1.0" encoding="UTF-8"?>
<Request xmlns="urn:oasis:names:tc:xacml:2.0:context:schema:os"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:oasis:names:tc:xacml:2.0:context:schema:os access_control-xacml-2.0-context-schema-os.xsd">
<Subject>
<Attribute
AttributeId="urn:oasis:names:tc:xacml:1.0:subject:subject-id"
DataType="http://www.w3.org/2001/XMLSchema#string">
<AttributeValue>Julius Hibbert</AttributeValue>
</Attribute>
</Subject>
<Resource>
<Attribute
AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-id"
DataType="http://www.w3.org/2001/XMLSchema#anyURI">
<AttributeValue>http://medico.com/record/patient/BartSimpson</AttributeValue>
</Attribute>
</Resource>
<Action>
<Attribute
AttributeId="urn:oasis:names:tc:xacml:1.0:action:action-id"
DataType="http://www.w3.org/2001/XMLSchema#string">
<AttributeValue>read</AttributeValue>
</Attribute>
</Action>
<Environment/>
</Request> |
In XACML 3.0, these categories are indicated using XML attributes instead of XML element tags:
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<?xml version="1.0" encoding="utf-8"?>
<Request xsi:schemaLocation="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17 http://docs.oasis-open.org/xacml/3.0/xacml-core-v3-schema-wd-17.xsd" ReturnPolicyIdList="false" CombinedDecision="false" xmlns="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<Attributes Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject">
<Attribute IncludeInResult="false" AttributeId="urn:oasis:names:tc:xacml:1.0:subject:subject-id">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">Julius Hibbert</AttributeValue>
</Attribute>
</Attributes>
<Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource">
<Attribute IncludeInResult="false" AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-id">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#anyURI">http://medico.com/record/patient/BartSimpson</AttributeValue>
</Attribute>
</Attributes>
<Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action">
<Attribute IncludeInResult="false" AttributeId="urn:oasis:names:tc:xacml:1.0:action:action-id">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">read</AttributeValue>
</Attribute>
</Attributes>
<Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:environment" />
</Request> |
The <Subject> element in XACML 2.0 becomes <Attributes Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject"> in XACML 3.0, for example. This is the same for the resource, environment, and action categories.
JSON Support with XACML 3.0
JSON (JavaScript Object Notation) is a lightweight, easy-to-work with format that is typically used in data exchange. WSO2 Identity Server supports sending XACML requests in JSON format via REST calls, and also supports recieving responses in the JSON format in your an authorization flow.
Following are some of the key points you need to keep in mind when you work with XACML 3.0 JSON requests and responses:
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For a tutorial on how to send XACML requests in JSON format via the XACML REST profile and recieve responses in the JSON format in your authorization flow, see Fine-grained Authorization using XACML Requests in JSON Format.
For a tutorial on how to you can use the XACML Multiple Decision Profile (MDP) with JSON via WSO2 Identity Server, see XACML Multiple Decision Profile Support using JSON.