OASIS Mailing List ArchivesView the OASIS mailing list archive below
or browse/search using MarkMail.

 


Help: OASIS Mailing Lists Help | MarkMail Help

xacml message

[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]


Subject: RE: [xacml] Updated policy template wiki


Erik,

Trying via a different angle. Let us first concentrate on the requirement, ignoring the modality (static, dynamic), exact mechanism (PIP involves or not)  and syntax.

1a) I have a very large number of policies (say, N > 10000) that are all identical, except for the constant values that contain in their access rules. Every single one of these policies has a unique identity.
1b) We build one template which, given the correct dataset, can produce the same N policy instances

Let now introduce the modality. There are two use-cases:

2a) The policy authority uses the template mechanism to ease the production of the N policy instances, which are all produced before being distributed for execution. Organizations implementing the policy do not see the policy template, only the N policy instances
2b) The policy authority distributes the its policy template to organizations. Each organization need to supply n policy data (n is a small number, typically between 1 and 100) which, combined with the policy template, produces n policy instances

The "iteration" can occur on either 2a or 2b (i.e. iterate through N policy data, or through n policy data). Objective is to produce the N or n policy instances.
The produces policy instances are (my original proposal), just plain core XACML 3.0 policies, that then can be used to provide standard authorization decision.

The discussion became confusing with the introduction of possible dynamic reduction, occurring at the time of authorization decision. Then the reduction mechanism needs to know the policy template and the policy dataset so it can reduce the policy instance, before evaluating the rules with input from (subject, resource, environment) attributes.

Again I want to stress out that whatever mechanism and syntax need to support both use cases 1a and 1b.

I hope this helped
Jean-Paul

-----Original Message-----
From: Erik Rissanen [mailto:erik@axiomatics.com]
Sent: Wednesday, October 10, 2012 09:25
To: Steven Legg
Cc: Danny Thorpe; Jean-Paul Buu-Sao; xacml@lists.oasis-open.org
Subject: Re: [xacml] Updated policy template wiki

Steven,

Sorry, but it's still a bit unclear to me. Ok, I get it that if you have one template and N template datasets, then you get N policies.

But why does that matter?

When a PEP calls to a PDP, the PDP is supposed to provide a single decision (not doing multi requests now) so this iteration does not need to happen. The PIP only needs to select the one dataset which applies to this particular request.

Best regards,
Erik



On 2012-10-10 08:58, Steven Legg wrote:
>
> Erik,
>
> On 10/10/2012 4:57 PM, Erik Rissanen wrote:
>> Steven,
>>
>> Whatever information you are using to select the right template data
>> when filling in the right template with the right data, could also be
>> available to a PIP which would then know which attribute values to
>> provide for any attribute designator. Or is there something I don't
>> understand in the discussion?
>
> The singular/plural ambiguity around "data" in policy template data is
> bothersome, and not helpful to clarity, so I'm going to start saying
> policy template data set (singular) and policy template data sets
> (plural).
>
> In the case of a Policy Template Engine (PTE), the inputs are a policy
> template and any number of policy template data sets. The PTE just
> goes into a loop where it makes a copy of the policy template
> replacing the parameters in the template (in whatever syntax is used
> to represent them) with the corresponding parameter values in the
> current policy template data set it is considering in the current
> iteration of the loop. The PTE considers one, and only one, policy
> template data set in each iteration. The values of the parameters,
> either single values or bags, will typically be different on each
> iteration because they come from a different policy template data set.
> Each time around the loop the PTE spits out a policy template
> instance, which is a normal policy without parameters. If there are N
> policy template data sets, then there are N output policies. There is
> no explicit information that the PTE uses to decide which policy
> template data set to use.
> The selection is inherent in the loop it performs.
>
> Dynamic template reduction has to have the same effect as a PTE, which
> means that the PDP has to evaluate the policy template, which is now
> masquerading as a normal policy, as many times as there are policy
> template data sets known to the PIP (or alternatively, the context
> handler). Effectively, PIPs currently act as though there is only ever
> one policy template data set.
> Standard PIPs don't
> have the capability of storing multiple alternative sets of
> attributes. Nor is there a mechanism that a PDP could use to tell the
> PIP which set it wants right now.
>
> Any clearer ?
>
> Regards,
> Steven
>
>>
>> Best regards,
>> Erik
>>
>> On 2012-10-10 03:28, Steven Legg wrote:
>>>
>>> Danny,
>>>
>>> On 10/10/2012 4:59 AM, Danny Thorpe wrote:
>>>
>>> [snip]
>>>
>>>> The equivalent of dynamic policy template reduction would require
>>>> setting up a PIP with the PDP to provide the appropriate
>>>> template-data values for a particular attribute ID when the PDP
>>>> evaluates the <AttributeDesignator>.  The PIP would need to be able
>>>> to distinguish between your two template cases below (Curtiss,
>>>> Packard vs Curtiss, Spad). If the PIP knew the context of which
>>>> policy ID an <AttributeDesignator> was being evaluated in, the PIP
>>>> could make the decision of whether to return (Curtiss, Packard) or
>>>> (Curtiss,
>>>> Spad) to provide the semantics of the original policy template
>>>> concept.  Knowledge of the PDP evaluation state by PIPs is not part
>>>> of the XACML spec, but could be provided by an implementation.
>>>>
>>>> I could imagine manipulating the policy ID to indicate what
>>>> substitution group(s) the policy belongs to.
>>>> Policy template (ID = "ABC") + parameter data set 1 => policy
>>>> ID="ABC/1". Policy template (ID = "ABC") + parameter data set 2 =>
>>>> policy ID="ABC/2".  The policy bodies are identical, but their IDs
>>>> differ.
>>>>
>>>> A more generalized solution would be to tie the parameter
>>>> substitution group selection to some artifact of the request
>>>> (subject, resource) or the environment (PDP host organization). PIP
>>>> returns parameter data set 1 for the target attribute ID if the
>>>> request context also contains a "green apple" attribute, else the
>>>> PIP returns parameter data set 2.  PIP returns parameter data set 1
>>>> if the organization's country is X, parameter data set 2 if the
>>>> organization's country is Y, etc.
>>>>
>>>> But the PIP only needs to be that smart if the PDP is multi-tenant.
>>>> In the use case of a shared policy
>>>> (template) needing to be customized to a particular organization's
>>>> specific details (parameter data), if the PDP is dedicated to that
>>>> one organization, the PIP could simply be loading the specific
>>>> details (parameter
>>>> data) from a config file. No need for decision branches in the PIP
>>>> at all.
>>>
>>> You only seem to be considering one possibility of use case 2 of the
>>> Policy Template Profile. I read use case 2 as allowing that the
>>> customization for a particular organization (i.e., the organization
>>> making use of the policy template, not the organizations that might
>>> be mentioned in the parameter
>>> data) could involve many policy template data. Those policy template
>>> data may overlap with the policy template data of another
>>> organization using the same template, or be completely different
>>> from the policy template data used by another organization using the
>>> same template. Use case 1 also calls for many policy template data
>>> in use at the same organization. I seem to recall it being written
>>> somewhere that the policy template data may number in the thousands.
>>>
>>> For dynamic template reduction where there are multiple policy
>>> template data, we can't rely on information in the request to cause
>>> the PIP to select one parameter group. The PDP has to repeatedly
>>> evaluate the policy template causing (somehow) the PIP to return a
>>> different parameter group each time, each parameter group
>>> corresponding to a different policy template data, and this must
>>> occur during the evaluation of a single authorization request.
>>>
>>> Regards,
>>> Steven
>>>
>>>>
>>>> -Danny
>>>>
>>>> *Danny Thorpe *
>>>>
>>>> Authorization Architect
>>>>
>>>> *Dell*| Identity & Access Management, Quest Software
>>>>
>>>> Quest Software is now part of Dell.
>>>>
>>>> *From:*Jean-Paul Buu-Sao [mailto:jean-paul.buu-sao@tscp.org]
>>>> *Sent:* Tuesday, October 09, 2012 1:40 AM
>>>> *To:* Erik Rissanen; Steven Legg
>>>> *Cc:* Danny Thorpe; xacml@lists.oasis-open.org
>>>> *Subject:* RE: [xacml] Updated policy template wiki
>>>>
>>>> For sake of clarity I would like to rephrase the thought process.
>>>>
>>>> Here is the excerpt of a policy (TAA-1.1), expressing that the
>>>> subject attribute
>>>> "http://schemas.tscp.org/2012-03/claims/OrganizationID"; must be in
>>>> the bag {"Curtiss", "Packard"}
>>>>
>>>>      <Condition
>>>> FunctionId="urn:oasis:names:tc:xacml:1.0:function:and">
>>>>
>>>>        <Apply xsi:type="AtLeastMemberOf"
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-at-least-o
>>>> ne-member-of">
>>>>
>>>>
>>>>          <Apply
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-bag">
>>>>
>>>> <AttributeValue
>>>> DataType="http://www.w3.org/2001/XMLSchema#string";>Curtiss</Attribu
>>>> teValue>
>>>>
>>>>            <AttributeValue
>>>> DataType="http://www.w3.org/2001/XMLSchema#string";>Packard</Attribu
>>>> teValue>
>>>>
>>>>          </Apply>
>>>>
>>>>          <AttributeDesignator
>>>> AttributeId="http://schemas.tscp.org/2012-03/claims/OrganizationID";
>>>> DataType="http://www.w3.org/2001/XMLSchema#string"; />
>>>>
>>>>        </Apply>
>>>>
>>>>        (etc...)
>>>>
>>>>      </Condition>
>>>>
>>>> Here is the excerpt of a policy (TAA-1.2), expressing that the
>>>> subject attribute
>>>> "http://schemas.tscp.org/2012-03/claims/OrganizationID"; must be in
>>>> the bag {"Curtiss", "Spad"}
>>>>
>>>>      <Condition
>>>> FunctionId="urn:oasis:names:tc:xacml:1.0:function:and">
>>>>
>>>>        <Apply xsi:type="AtLeastMemberOf"
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-at-least-o
>>>> ne-member-of">
>>>>
>>>>
>>>>          <Apply
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-bag">
>>>>
>>>> <AttributeValue
>>>> DataType="http://www.w3.org/2001/XMLSchema#string";>Curtiss</Attribu
>>>> teValue>
>>>>
>>>>            <AttributeValue
>>>> DataType="http://www.w3.org/2001/XMLSchema#string";>Spad</AttributeV
>>>> alue>
>>>>
>>>>          </Apply>
>>>>
>>>>          <AttributeDesignator
>>>> AttributeId="http://schemas.tscp.org/2012-03/claims/OrganizationID";
>>>> DataType="http://www.w3.org/2001/XMLSchema#string"; />
>>>>
>>>>        </Apply>
>>>>
>>>>        (etc...)
>>>>
>>>>      </Condition>
>>>>
>>>> The two policies (TAA-1.1 and TAA-1.2) are similar, with the
>>>> exception of the hard-coded values of the string bags used by the
>>>> AtLeastMemberOf function. The idea is to have only one policy that
>>>> does not contain these hard-coded values. Instead we have a
>>>> construct that would substitute the appropriate values. In the
>>>> example above: {"Curtiss", "Packard"} for TAA-1.1, {"Curtiss",
>>>> "Spad"} for TAA-1.2.
>>>>
>>>> My initial proposal was to using the element <AttributeValue>
>>>> without qualifying its contents values, but by specifying a
>>>> ParameterId attribute, that would allow to substitute the
>>>> appropriate values:
>>>>
>>>>      <Condition
>>>> FunctionId="urn:oasis:names:tc:xacml:1.0:function:and">
>>>>
>>>>        <Apply xsi:type="AtLeastMemberOf"
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-at-least-o
>>>> ne-member-of">
>>>>
>>>>
>>>>          <Apply
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-bag">
>>>>
>>>> <AttributeValue ParameterId="organizations"
>>>> DataType=http://www.w3.org/2001/XMLSchema#string/>
>>>>
>>>>          </Apply>
>>>>
>>>>          <AttributeDesignator
>>>> AttributeId="http://schemas.tscp.org/2012-03/claims/OrganizationID";
>>>> DataType="http://www.w3.org/2001/XMLSchema#string"; />
>>>>
>>>>        </Apply>
>>>>
>>>>      (etc...)
>>>>
>>>>      </Condition>
>>>>
>>>> I understand that instead, and in order to achieving the same
>>>> effect, Erik's proposal is to replace the <AttributeValue
>>>> ParameterId=...> construct with the more standard
>>>> <AttributeDesignator> construct, given something like:
>>>>
>>>>      <Condition
>>>> FunctionId="urn:oasis:names:tc:xacml:1.0:function:and">
>>>>
>>>>        <Apply xsi:type="AtLeastMemberOf"
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-at-least-o
>>>> ne-member-of">
>>>>
>>>>
>>>>          <Apply
>>>> functionId="urn:oasis:names:tc:xacml:1.0:function:string-bag">
>>>>
>>>> <AttributeDesignator
>>>> CategoryId="urn:oasis:names:tc:xacml:1.0:policy:"
>>>> AttributeId="organizations"
>>>> DataType="http://www.w3.org/2001/XMLSchema#string"; />
>>>>
>>>>          </Apply>
>>>>
>>>>          <AttributeDesignator
>>>> AttributeId="http://schemas.tscp.org/2012-03/claims/OrganizationID";
>>>> DataType="http://www.w3.org/2001/XMLSchema#string"; />
>>>>
>>>>        </Apply>
>>>>
>>>>      (etc...)
>>>>
>>>>      </Condition>
>>>>
>>>> If my interpretation is correct (at least on the intent, not on
>>>> exact syntax; Erik, I apologize if I totally missed your point),
>>>> then some questions arise:
>>>>
>>>> A.1) How would the authorization engine know where to go and fetch
>>>> the desired values (i.e. from the TAA-1.1 template-data or the
>>>> TAA-1.2 template-data)?
>>>>
>>>> A.2) The <AttributeDesignator> construct was, so far, meant to
>>>> retrieve attributes values from (Subject, Resource, Environment)
>>>> attributes. Are we introducing the possibility for the same
>>>> construct to also retrieve attribute values from (policy-template)
>>>> attributes? If so we need to make it explicit on the specification,
>>>> I would think.
>>>>
>>>> B) Can the two use-cases called out at the beginning of
>>>> [https://wiki.oasis-open.org/xacml/Policy%20Template%20Profile] be
>>>> supported by <AttributeDesignator>?
>>>>
>>>> I assumed that use-case 1 requires a static reduction, that happens
>>>> far before any actual authorization decision; hence
>>>> <AttributeDesignator> cannot be used for the purpose of
>>>> parameterization. If my assumption is correct, then we need a
>>>> different mechanism to support use-case 1, which is damageable. My
>>>> proposal was to find a single syntax that would equally support
>>>> both use-cases.
>>>>
>>>> Thanks,
>>>>
>>>> Jean-Paul
>>>>
>>>> -----Original Message-----
>>>> From: Erik Rissanen [mailto:erik@axiomatics.com]
>>>> Sent: Tuesday, October 09, 2012 08:32
>>>> To: Steven Legg
>>>> Cc: Jean-Paul Buu-Sao; Danny Thorpe; xacml@lists.oasis-open.org
>>>> <mailto:xacml@lists.oasis-open.org>
>>>> Subject: Re: [xacml] Updated policy template wiki
>>>>
>>>> Steven,
>>>>
>>>> I am arguing against the whole concept of a template, thus there is
>>>> no Policy Template Engine in my proposal.
>>>>
>>>> What I am trying to say is that instead of adding a Policy Template
>>>> Engine to the PDP before the policy is evaluated by the XACML
>>>> engine, you can just use a regular XACML policy in the XACML
>>>> engine.
>>>>
>>>> You can solve the same use case this way. Say that you want a
>>>> template which has a parameter called "foo"
>>>> and then a Policy Template Engine which substitutes "foo" with
>>>> values before the XACML engine. Instead you can have a regular
>>>> XACML policy with attribute designator "foo" and a PIP which
>>>> provides the value which would have been provided by the policy
>>>> template engine.
>>>>
>>>> Best regards,
>>>>
>>>> Erik
>>>>
>>>> On 2012-10-09 02:46, Steven Legg wrote:
>>>>
>>>>>
>>>>
>>>>> Erik,
>>>>
>>>>>
>>>>
>>>>> Sorry, I read too much into what you were saying. Please disregard
>>>>> my
>>>>
>>>>> previous response.
>>>>
>>>>>
>>>>
>>>>> On 8/10/2012 5:38 PM, Erik Rissanen wrote:
>>>>
>>>>>> Steven,
>>>>
>>>>>>
>>>>
>>>>>> Yes, just replace all parameters with attribute designators.
>>>>
>>>>>
>>>>
>>>>> An issue with using attribute designators as parameters is that
>>>>> there
>>>>
>>>>> is ambiguity for the Policy Template Engine to resolve. Some
>>>>> attribute
>>>>
>>>>> designators in the policy template are "real" and are preserved as
>>>>> is,
>>>>
>>>>> and the other attribute designators are actually parameters that
>>>>> need
>>>>
>>>>> to be replaced by a bag of attribute values from the policy
>>>>> template
>>>>
>>>>> data.
>>>>
>>>>>
>>>>
>>>>> Your example only has one parameter as a designator and that
>>>>
>>>>> designator uses the same URI for the Category and AttributeId.
>>>>> Were
>>>>
>>>>> you intending that equivalence as a way of distinguishing an
>>>>> attribute
>>>>
>>>>> designator that is actually a parameter, or is it just because you
>>>>> had
>>>>
>>>>> to put something in the Category ? A Policy Template Engine could
>>>>
>>>>> always look in the policy template data to work out which
>>>>> designators
>>>>
>>>>> are really parameters, but I think it would be better if it were
>>>>> clear
>>>>
>>>>> from the designator. I suggest using a special category URI just
>>>>> for
>>>>
>>>>> parameters.
>>>>
>>>>>
>>>>
>>>>> The attribute designators that are actually parameters should
>>>>> always
>>>>
>>>>> use MustBePresent="true" so that an implementation that blindly
>>>>
>>>>> evaluates a policy template as a normal policy will appropriately
>>>>
>>>>> return an indeterminate decision.
>>>>
>>>>>
>>>>
>>>>> It seems we have three proposals for representating parameters in
>>>>
>>>>> policy
>>>>
>>>>> templates:
>>>>
>>>>>
>>>>
>>>>> (1) Just use attribute designators. This means that targets can't
>>>>> have
>>>>
>>>>> parameters, but on-permit-apply-second can be used to get the same
>>>>
>>>>> effect.
>>>>
>>>>> Policy template data writers can determine whether a parameter is
>>>>
>>>>> single-valued or multi-valued by seeing whether the corresponding
>>>>
>>>>> attribute designator is wrapped in type-one-and-only.
>>>>
>>>>>
>>>>
>>>>> (2) <ValueParameter> and <BagParameter> elements. Targets can have
>>>>
>>>>> value parameters, but not bag parameters, though
>>>>
>>>>> on-permit-apply-second can be used to get the same effect. It's
>>>>
>>>>> obvious to policy template data writers what the parameters are
>>>>> and
>>>>
>>>>> whether a parameter is single-valued or multi-valued.
>>>>
>>>>>
>>>>
>>>>> (3) ParameterId XML attribute on <AttributeValue> elements. It's
>>>>
>>>>> reasonably obvious to policy template data writers what the
>>>>> parameters
>>>>
>>>>> are. An additional XML attribute to indicate whether the parameter
>>>>> is
>>>>
>>>>> single-valued or multi-valued would make this solution cleaner.
>>>>
>>>>> Targets can have value parameters. Targets could also have bag
>>>>
>>>>> parameters provided the target is transformed by the Policy
>>>>> Template
>>>>
>>>>> Engine. Alternatively, bag parameters in targets could be
>>>>> disallowed
>>>>
>>>>> because on-permit-apply-second can be used to get the same effect.
>>>>
>>>>>
>>>>
>>>>> I don't see a compelling need for transformations of conditions.
>>>>
>>>>> Proposals
>>>>
>>>>> (1) and (2) don't lend themselves to transformations, but it could
>>>>> be
>>>>
>>>>> done.
>>>>
>>>>> The difference in the proposals is mostly around the syntax for
>>>>
>>>>> representing parameters.
>>>>
>>>>>
>>>>
>>>>> Regards,
>>>>
>>>>> Steven
>>>>
>>>>>
>>>>
>>>>>>
>>>>
>>>>>> I don't understand why you need to evaluate the template twice. I
>>>>
>>>>>> tried to understand it from the wiki, but to me it all looks like
>>>>
>>>>>> simple value substitution, which can handled better with
>>>>>> attribute
>>>>
>>>>>> designators.
>>>>
>>>>>>
>>>>
>>>>>> Best regards,
>>>>
>>>>>> Erik
>>>>
>>>>>>
>>>>
>>>>>> On 2012-10-08 04:32, Steven Legg wrote:
>>>>
>>>>>>>
>>>>
>>>>>>> Erik,
>>>>
>>>>>>>
>>>>
>>>>>>> On 5/10/2012 6:03 PM, Erik Rissanen wrote:
>>>>
>>>>>>>> Jean-Paul,
>>>>
>>>>>>>>
>>>>
>>>>>>>> I put in one such example on the wiki page. Search for
>>>>
>>>>>>>> "on-permit-apply-second" and you will find it.
>>>>
>>>>>>>
>>>>
>>>>>>> This strategy only works if there is one policy template data
>>>>>>> for
>>>>
>>>>>>> the policy template. In general, there may be many policy
>>>>>>> template
>>>>
>>>>>>> data per policy template. The example in the wiki has two:
>>>>>>> TAA-1.1 and TAA-1.2.
>>>>
>>>>>>>
>>>>
>>>>>>> Although you didn't do it, I assume you meant to replace the
>>>>
>>>>>>> parameters in the condition with attribute designators as well,
>>>>
>>>>>>> i.e., designators for "organizations", "nationals" and
>>>>>>> "workEfforts".
>>>>
>>>>>>>
>>>>
>>>>>>> The policy needs to be evaluated twice. The first time the
>>>>>>> attribute
>>>>
>>>>>>> designator for PolicyIdOnResource needs to return
>>>>
>>>>>>> "urn:curtiss:ba:taa:taa-1.1", the designator for "organizations"
>>>>
>>>>>>> needs to return the bag of { "Curtiss", "Packard" }, the
>>>>>>> designator
>>>>
>>>>>>> for "nationals" needs to return the bag of { "US", "GB" }, and
>>>>
>>>>>>> "workEfforts" needs to return { "DetailedDesign", "Simulation" }.
>>>>
>>>>>>> The second time, PolicyIdOnResource needs to return
>>>>
>>>>>>> "urn:curtiss:ba:taa:taa-1.2", "organizations" needs to return {
>>>>
>>>>>>> "Curtiss", "Spad" }, "nationals" needs to return { "US", "FR" }
>>>>>>> and
>>>>
>>>>>>> "workEfforts"
>>>>
>>>>>>> needs to return { "Integration", "Simulation" }.
>>>>
>>>>>>>
>>>>
>>>>>>> Of course, we don't currently have a way to cause a policy to be
>>>>
>>>>>>> evaluated multiple times with the attribute designators
>>>>>>> returning
>>>>
>>>>>>> different bags each time. For one thing, the result of an
>>>>>>> attribute
>>>>
>>>>>>> designator is fixed for the entire duration of the processing of
>>>>>>> an
>>>>
>>>>>>> authorization request. The expansion of the policy template into
>>>>>>> a
>>>>
>>>>>>> policy template instance for each policy template data achieves
>>>>>>> the
>>>>
>>>>>>> same end.
>>>>
>>>>>>>
>>>>
>>>>>>> The use of on-permit-apply-second is a good idea for removing
>>>>>>> the
>>>>
>>>>>>> need for any special processing of parameters in targets.
>>>>
>>>>>>>
>>>>
>>>>>>> Regards,
>>>>
>>>>>>> Steven
>>>>
>>>>>>>
>>>>
>>>>>>>>
>>>>
>>>>>>>> Best regards,
>>>>
>>>>>>>> Erik
>>>>
>>>>>>>>
>>>>
>>>>>>>> On 2012-10-04 23:01, Jean-Paul Buu-Sao wrote:
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Greetings,
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Apologies for missing the call today, as I was in a TSCP
>>>>>>>>> event,
>>>>
>>>>>>>>> together with Gerry and David of Axiomatics.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> I have been much interested in the last findings, and agree
>>>>>>>>> that
>>>>
>>>>>>>>> if the "template" property that we are (all, I think) looking
>>>>>>>>> for
>>>>
>>>>>>>>> could be achieved with standard the <AttributeDesignator>
>>>>
>>>>>>>>> construct, rather than introducing new concepts, then this
>>>>>>>>> would
>>>>
>>>>>>>>> be for the better.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> May I suggest that, in order to verify this assertion (so to
>>>>
>>>>>>>>> speak), some folks, such as Erik or Danny, would be kind
>>>>>>>>> enough to
>>>>
>>>>>>>>> propose an alternate proposal to the sample found on our Wiki
>>>>
>>>>>>>>> (https://wiki.oasis-open.org/xacml/Policy%20Template%20Profile%20Examples)?
>>>>>>>>>
>>>>
>>>>>>>>> By the way, as a word of
>>>>
>>>>>>>>> caution, please disregard the in-correctness of the XCAML 3.0
>>>>>>>>> of
>>>>
>>>>>>>>> section 1. of the example (yes the devil is in the details,
>>>>>>>>> and
>>>>
>>>>>>>>> David shown me how this example could be made compliant).
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Thanks in advance,
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Jean-Paul
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> *From:*xacml@lists.oasis-open.org
>>>>
>>>>>>>>>  [mailto:xacml@lists.oasis-open.org]
>>>>>>>>> <mailto:[mailto:xacml@lists.oasis-open.org]> *On Behalf Of
>>>>>>>>> *Danny Thorpe
>>>>
>>>>>>>>> *Sent:* Thursday, October 04, 2012 20:11
>>>>
>>>>>>>>> *To:* Erik Rissanen; xacml@lists.oasis-open.org
>>>>>>>>> <mailto:xacml@lists.oasis-open.org>
>>>>
>>>>>>>>> *Subject:* RE: [xacml] Updated policy template wiki
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> When the original proposal for policy templates was brought
>>>>
>>>>>>>>> forward, I noted that simply replacing a single AttributeValue
>>>>
>>>>>>>>> element with a list of values from the policy template
>>>>>>>>> <Parameter>
>>>>
>>>>>>>>> would fail in <Match> expressions, since <Match> is very
>>>>>>>>> explicit
>>>>
>>>>>>>>> about one value, one designator/selector.  I offered a
>>>>>>>>> transform
>>>>
>>>>>>>>> to help produce valid match expressions.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> AttributeDesignator does provide similar
>>>>
>>>>>>>>> "insert-multiple-values-here" operations to the policy
>>>>>>>>> template
>>>>
>>>>>>>>> substitution behavior, but I believe the suggestion of policy
>>>>
>>>>>>>>> parameterization came up because of situations in which
>>>>
>>>>>>>>> AttributeDesignator cannot be used. Comparing an  attribute
>>>>
>>>>>>>>> against a static list of test values (specific to an
>>>>>>>>> organization
>>>>
>>>>>>>>> or location and applied to a generic policy), for example, is
>>>>>>>>> a
>>>>
>>>>>>>>> many-to-many comparison, but cannot be expressed in a <Match>
>>>>
>>>>>>>>> element.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> As we discussed on the TC call today, we're finding more
>>>>
>>>>>>>>> difficulties with parameter substitution the deeper we dig.
>>>>>>>>> Steven
>>>>
>>>>>>>>> Legg noted in an earlier email that some Xacml functions that
>>>>>>>>> take
>>>>
>>>>>>>>> single <AttributeValue> won't work if multiple values are
>>>>>>>>> dropped
>>>>
>>>>>>>>> in to replace the <AttributeValue>. This means some sort of
>>>>
>>>>>>>>> expression transform will be necessary in condition
>>>>>>>>> expressions as
>>>>
>>>>>>>>> well to move policy templates forward.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> In light of these increasing complexities and challenges, I'm
>>>>
>>>>>>>>> beginning to agree with you that perhaps the policy template
>>>>>>>>> use
>>>>
>>>>>>>>> case can better be addressed using the existing
>>>>
>>>>>>>>> <AttributeDesignator>.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> This would mean:
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> 1.Giving up parameterization behavior in <Match> expressions
>>>>>>>>> and
>>>>
>>>>>>>>> moving that logic into conditions using <AttributeDesignator>
>>>>>>>>> to
>>>>
>>>>>>>>> reference an attribute ID representing the parameterization data.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> 2.Moving parameterization data from a static policy generator
>>>>>>>>> step
>>>>
>>>>>>>>> to a PIP to fill <AttributeDesignator> references to a
>>>>>>>>> particular
>>>>
>>>>>>>>> attribute ID with parameterization data in the PDP at auth
>>>>>>>>> request
>>>>
>>>>>>>>> evaluation time.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Using <AttributeDesignator> instead of policy templates does
>>>>
>>>>>>>>> impact the use case quite a bit because populating PIP data is
>>>>>>>>> not
>>>>
>>>>>>>>> part of the Xacml spec. Policies could be shared between
>>>>
>>>>>>>>> organizations per the use case, but how the parameterization
>>>>>>>>> data
>>>>
>>>>>>>>> is applied to those policies would become a vendor-specific
>>>>
>>>>>>>>> implementation detail.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> I can see the attraction of parameterizing policies to allow
>>>>
>>>>>>>>> up-front synthesis of specific policies, but as we say "the
>>>>>>>>> devil
>>>>
>>>>>>>>> is in the details." The details are winning. :/
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> -Danny
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> *Danny Thorpe *
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Authorization Architect
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Dell | Identity & Access Management, Quest Software
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Quest Software is not part of Dell.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> *From:*xacml@lists.oasis-open.org
>>>>
>>>>>>>>> <mailto:xacml@lists.oasis-open.org>
>>>>
>>>>>>>>>  [mailto:xacml@lists.oasis-open.org]
>>>>>>>>> <mailto:[mailto:xacml@lists.oasis-open.org]>
>>>>
>>>>>>>>> <mailto:[mailto:xacml@lists.oasis-open.org]> *On Behalf Of
>>>>>>>>> *Erik
>>>>
>>>>>>>>> Rissanen
>>>>
>>>>>>>>> *Sent:* Thursday, October 04, 2012 4:42 AM
>>>>
>>>>>>>>> *To:* xacml@lists.oasis-open.org
>>>>>>>>> <mailto:xacml@lists.oasis-open.org>
>>>>
>>>>>>>>> <mailto:xacml@lists.oasis-open.org>
>>>>
>>>>>>>>> *Subject:* Re: [xacml] Updated policy template wiki
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> All,
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> I still fail to see why this is useful.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> If you take a policy template, and replace each <Parameter>
>>>>>>>>> with
>>>>
>>>>>>>>> an appropriate <AttributeDesignator>, then you get a regular
>>>>>>>>> XACML
>>>>
>>>>>>>>> policy, and the PEP/PDP can "fill in"
>>>>
>>>>>>>>> the "template" at runtime using normal XACML attributes.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Why do we need a new standard? In particular I would be
>>>>>>>>> opposed to
>>>>
>>>>>>>>> "implementation option C", that is a PDP would construct the
>>>>
>>>>>>>>> policy from the template at runtime.
>>>>
>>>>>>>>> That's lots of heavy machinery for no gain.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> Best regards,
>>>>
>>>>>>>>> Erik
>>>>
>>>>>>>>>
>>>>
>>>>>>>>> On 2012-09-20 20:25, Danny Thorpe wrote:
>>>>
>>>>>>>>>
>>>>
>>>>>>>>>     I've updated the policy template wiki
>>>>
>>>>>>>>> (https://wiki.oasis-open.org/xacml/Policy%20Template%20Profile
>>>>>>>>> )
>>>>
>>>>>>>>>     with text about required Match expression rewriting in
>>>>
>>>>>>>>> parameter substitution and optional use of
>>>>
>>>>>>>>>     AttributeDesignators and AttributeSelectors in Parameter
>>>>>>>>> data
>>>>
>>>>>>>>> in dynamic policy template reduction
>>>>
>>>>>>>>>     implementations.
>>>>
>>>>>>>>>
>>>>
>>>>>>>>>     -Danny
>>>>
>>>>>>>>>
>>>>
>>>>>>>>>     *Danny Thorpe *
>>>>
>>>>>>>>>
>>>>
>>>>>>>>>     Product Architect | | *Quest Software*- /Now including the
>>>>
>>>>>>>>> people and products of BiTKOO/ |
>>>>
>>>>>>>>> www.quest.com <http://www.quest.com> <http://www.quest.com>
>>>>
>>>>>>>>>
>>>>
>>>>>>>>
>>>>
>>>>>>>
>>>>
>>>>>>
>>>>
>>>>>
>>>>
>>>
>>
>



[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]