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Subject: RE: [xacml-users] XACML Request with multiple subjects of the sameattributeID?
No we have not considered that
but thanks for bringing it up, it seems like a good model. I’ll
need to see if our XACML implementation can do something like that. It
might only support PDP functionality. Mike Ryerse 360-725-3908 From: Tyson, Paul H
[mailto:PTyson@bellhelicopter.textron.com] Mike, One more note on the
architecture you described. Did you consider putting the ldap request in
the PIP instead of the PEP? That way, your original XACML request would
just contain the user-id and resource-id. It would keep your PEP leaner
and dumber. You would add a custom context handler to look up the ldap
groups for a user as required by the PDP when it processes a request.
Use caching to improve performance. This makes your PIP fatter and
smarter, of course. You must analyze your environment and future growth
possibilities to see which approach is better in the long run. Regards, --Paul From: Ryerse, Mike (DIS)
[mailto:MikeRy@DIS.WA.GOV] We’re considering the use XACML to manage access
control for some of our web services. I’m wondering if the XACML specification can support a
scenario where a request contains multiple subject attributes of the same
type. Specifically a list of all the LDAP groups the user is a member
of. When we receive a request with a username/password, and we build the
XACML request, we’d like to do an LDAP query on the user that gets a list
of all the LDAP groups they are a member of and put in the XACML request.
Then, the XACML policy would evaluate the request, and have a definition of what
specific group the user needs to be a member of to access the single
resource they are requesting. The presumption is that only one LDAP group permits access
to a given resource, but that when generating the XACML request you don’t
know which one it is. So we’d like to send all groups the user is a
member of and let the PDP figure out if the request is authorized or not.
If XACML is not designed to work like this maybe there is a better way to
handle this scenario? I’ve read about some folks mapping their
groups to generic names, but I don’t think it would work for us since we
have a very large number of groups already mapped to resources on another
access control platform. For example I’m wondering if you could do something
like the following request (files attached in case formatting gets all messed
up): <Request xmlns="urn:oasis:names:tc:xacml:2.0:context:schema:os" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <Subject> <Attribute AttributeId="urn:oasis:names:tc:xacml:1.0:subject:subject-id" DataType="http://www.w3.org/2001/XMLSchema#string"> <AttributeValue>michael</AttributeValue> </Attribute> <Attribute AttributeId="group" DataType="http://www.w3.org/2001/XMLSchema#string"> <AttributeValue>users</AttributeValue> </Attribute> <Attribute AttributeId="group" DataType="http://www.w3.org/2001/XMLSchema#string"> <AttributeValue>administrators</AttributeValue> </Attribute> <Attribute AttributeId="group" DataType="http://www.w3.org/2001/XMLSchema#string"> <AttributeValue>backupOperators</AttributeValue> </Attribute> </Subject> <Resource> <Attribute AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-id" DataType="http://www.w3.org/2001/XMLSchema#string"> <AttributeValue>/service/Address/URI</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> On the following Policy: <Policy PolicyID="LoginPolicy" RuleCombiningAlgID="urn:oasis:names:tc:xacml:1.0:rule-combining-algorithm:permit-overrides"> <Rule RuleID="LoginRule" Effect="Permit"> <Target> <Subjects>
<Attribute AttributeID="urn:oasis:names:tc:xacml:1.0:subject:subject-id" DataType="http://www.w3.org/2001/XMLSchema#string">
<AttributeValue>
Bob
</AttributeValue>
</Attribute> </Subjects> <Resources>
<ResourceMatch MatchID="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">/service/Address/URI</AttributeValue>
<ResourceAttributeDesignator DataType="http://www.w3.org/2001/XMLSchema#string" AttributeID="urn:oasis:names:tc:xacml:1.0:resource:resource-id" />
</ResourceMatch> </Resources> </Target> </Rule> <Rule RuleID="FinalRule" Effect="Deny"/> </Policy> Thanks for your help J Michael Ryerse | Enterprise Security Services | (360) 725-3908 |
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