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https://github.com/enygma/xacmlphp

An OASIS/XACML library for creating XACML-based PHP objects
https://github.com/enygma/xacmlphp

php xacml-php xacml-standard

Last synced: 5 days ago
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An OASIS/XACML library for creating XACML-based PHP objects

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README 

        
Xacml-php

==========================

The Xacml-php library is an implementation of the OASIS/XACML standard for Policy-based

authorization. It's a work in progress, but the basic concepts are there.



## The OASIS Standard



The [OASIS/XACML standard](http://docs.oasis-open.org/xacml/3.0/xacml-3.0-core-spec-os-en.pdf) is a

well-defined XML-based structure for evaluating attributes on Policies against attributes on Subjects

to see if there's a match (based on Operation rules and combining Algorithms).



#### Terminology:



- **PolicySet:** Set of Policy objects

- **Policy:** Defines the policies to evaluate for authoriation. Policies contain sets of Rules

    that are evaluated and the results are combined according to the Policy's Algorithm for an

    overall Policy pass/fail status

- **Rule:** A Rule is made of of a set of Matches (inside a Target) that are used to evaluate

    authorization

- **Match:** An object that defines the property to look at (Designator) and the value to check

    against (Value) and the Operation to perform (like "StringEqual") for Permit/Deny result

- **Attribute:** Property on a Subject, Resource, Action or Environment

- **Algorithm:** Evaluation method for combining results of the object (like Policy or Rule). In

    the OASIS spec, these are called *Functions*.

- **Effect:** According to the spec, this can only be "PERMIT" or "DENY"

- **Enforcer:** Point of enforcement of the access, called the PEP (Policy Enforcement Point)

    in the OASIS spec.

- **Decider:** The object that handles the decision logic, tracing down from Policies to Matches.

    Called the PDP (Policy Decision Point) in the OASIS spec.

- **Resource:** An object representing a "something" the Subject is trying to access.



## Example Usage:



This is a basic interpretation of the OASIS XACML structure and flow. It sets up the Policy structure

with Rules & Matches first, then assigns them to the Resource. Then, the Subject and Resource are

passed in to the Enforcer to check if they're allowed or not:



```php

setDecider($decider);



// Create some Matches

$match1 = new \Xacmlphp\Match('StringEqual', 'property1', 'TestMatch1', 'test');

$match2 = new \Xacmlphp\Match('StringEqual', 'property1', 'TestMatch2', 'test1234');



// Create a Target container for our Matches

$target = new \Xacmlphp\Target();

$target->addMatches(array($match1, $match2));



// Make a new Rule and add the Target to it

$rule1 = new \Xacmlphp\Rule();

$rule1->setTarget($target)

    ->setId('TestRule')

    ->setEffect('Permit')

    ->setDescription(

        'Test to see if there is an attribute on the subject'

        .'that exactly matches the word "test"'

    )

    ->setAlgorithm(new \Xacmlphp\Algorithm\DenyOverrides());



// Make two new policies and add the Rule to it (with our Match)

$policy1 = new \Xacmlphp\Policy();

$policy1->setAlgorithm('AllowOverrides')->setId('Policy1')->addRule($rule1);



$policy2 = new \Xacmlphp\Policy();

$policy2->setAlgorithm('DenyOverrides')->setId('Policy2')->addRule($rule1);



// Create the subject with its own Attribute

$subject = new \Xacmlphp\Subject();

$subject->addAttribute(

    new \Xacmlphp\Attribute('property1', 'test')

);



// Link the Policies to the Resource

$resource = new \Xacmlphp\Resource();

$resource

    ->addPolicy($policy1)

    ->addPolicy($policy2);



$environment = null;

$action = null;



$result = $enforcer->isAuthorized($subject, $resource);



/**

 * The Subject does have a property that's equal to "test" on the "property1"

 * attribute, but the default Operation is to "fail closed". The other Match,

 * for "test1234" failed and DenyOverrides wins so the return is false.

 */



echo "\n\n".' END RESULT: '.var_export($result, true);

echo "\n\n";



?>

```