REST API with WSO2 IS and XACML Policy - wso2

Question

We are using WSO2 IS as the Identity Bus for our solutions. We use WSO2 ESB and EI to implement our Integration and use OAuth mediator to connect an API from EI to IS.
Everything works fine in the EI, but we want to create an XACML policy to do two kinds of restrictions at the same time. First, authorize the user against the URI which can be hardcoded in the XACML or saved as a property in user claims. Secondly, authorize the user against the origin IP of the user, I mean imagine that every user saves its IP in its claims, then we check the invoker IP to match the user IP.
TO SUMMARIZE:
We make REST API in WSO2-ESB to implement our Integration and use OAuth mediator in that for securing our API. In WSO2-IS we create a service provider as sp1 and apply XACML policy to that. I want to create XACML policy to permit incoming requests just when client_ip is xxx.xxx.xxx.xxx and request URI is http://wso2ESB.uri/sampleApi/app and method is GET.
NOTE: Reading from values from a claim is not a big deal here!

Answer 1

Regarding your second requirement, You can define XACML policy as below by pointing IP address in subject category (since IP address can be retrieved from user profile). By default WSO2 Identity Server PIP (Policy Information Point) is underline user store.
XACML Request contains only username and XACML Policy contains IP Address therefore PIP resolve IP Address for given user.
XACML Policy
<Policy xmlns="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17" PolicyId="TestPolicy" RuleCombiningAlgId="urn:oasis:names:tc:xacml:1.0:rule-combining-algorithm:first-applicable" Version="1.0">
<Target>
<AnyOf>
<AllOf>
<Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">192.168.1.1</AttributeValue>
<AttributeDesignator AttributeId="http://wso2.org/claims/ipAddress" Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="true"></AttributeDesignator>
</Match>
</AllOf>
</AnyOf>
</Target>
<Rule Effect="Permit" RuleId="Rule-1">
<Target>
<AnyOf>
<AllOf>
<Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">test-resource</AttributeValue>
<AttributeDesignator AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-id" Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="true"></AttributeDesignator>
</Match>
</AllOf>
</AnyOf>
<AnyOf>
<AllOf>
<Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">POST</AttributeValue>
<AttributeDesignator AttributeId="urn:oasis:names:tc:xacml:1.0:action:action-id" Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="true"></AttributeDesignator>
</Match>
</AllOf>
</AnyOf>
</Target>
</Rule>
<Rule Effect="Deny" RuleId="Deny-Rule"></Rule>
</Policy>
<Request xmlns="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17" CombinedDecision="false" ReturnPolicyIdList="false">
<Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource">
<Attribute AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-id" IncludeInResult="false">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">test-resource</AttributeValue>
</Attribute>
</Attributes>
<Attributes Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject">
<Attribute AttributeId="urn:oasis:names:tc:xacml:1.0:subject:subject-id" IncludeInResult="false">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">gboss</AttributeValue>
</Attribute>
</Attributes>
<Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action">
<Attribute AttributeId="urn:oasis:names:tc:xacml:1.0:action:action-id" IncludeInResult="false">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">POST</AttributeValue>
</Attribute>
</Attributes>
</Request>
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Answer 2

Refer to the "Configuring Access Control Policy for a Service Provider" section of WSO2's documentation to enable the XACML based access control for Service provider. You need to enable "Enable Authorization" under "Local and Outbound Authentication Configuration" of your service provider and configure the XACML policy.
(In the policy, as you want to have the URI and IP as user claims, then create two new claims. Let's say http://wso2.org/claims/uri and http://wso2.org/claims/ip)
Then change the policy provided to check for these claims,
<Target>
<AnyOf>
<AllOf>
<Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">APP_NAME</AttributeValue>
<AttributeDesignator AttributeId="http://wso2.org/identity/sp/sp-name" Category="http://wso2.org/identity/sp" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="false"/>
</Match>
<Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">authenticate</AttributeValue>
<AttributeDesignator AttributeId="http://wso2.org/identity/identity-action/action-name" Category="http://wso2.org/identity/identity-action" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="true"></AttributeDesignator>
</Match>
</AllOf>
</AnyOf>
</Target>
<Rule Effect="Permit" RuleId="permit_by_uri_and_ip">
<Condition>
<Apply FunctionId="urn:oasis:names:tc:xacml:1.0:function:and">
<Apply FunctionId="urn:oasis:names:tc:xacml:1.0:function:string-is-in">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">URI</AttributeValue>
<AttributeDesignator AttributeId="http://wso2.org/claims/uri" Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="true"/>
</Apply>
<Apply FunctionId="urn:oasis:names:tc:xacml:1.0:function:string-is-in">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">IP</AttributeValue>
<AttributeDesignator AttributeId="http://wso2.org/claims/ip" Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="true"/>
</Apply>
</Apply>
</Condition>
</Rule>
<Rule Effect="Deny" RuleId="deny_others"/>
</Policy>
Then publish the policy. You can also refer to "Writing XACML3 Policies in WSO2 Identity Server" to get an understanding about writing the XACML policies.