MHonArc v2.5.0b2 -->
xacml message
[Date Prev]
| [Thread Prev]
| [Thread Next]
| [Date Next]
--
[Date Index]
| [Thread Index]
| [List Home]
Subject: RE: [xacml] summary of Frank's delegation proposal
In Round 2 of your Simple Example, shouldn't it be
Can Subjects D=Manager1 and S=Manager2 do Action A to Resource R?
rather than
Can Subjects D=Manager2 and S=Manager2 do Action A to Resource R?
As far as that goes, I'm not clear why (according to Step 3b) the new Subject corresponding to the Issuer is added to the request, rather than replacing the previous Subject. In other words (returning to Round 2 of the Simple Example),
Can Subject D=Manager1 do Action A to Resource R?
--
Steve Anderson
OpenNetwork
-----Original Message-----
From: Anne Anderson [mailto:Anne.Anderson@Sun.COM]
Sent: Tuesday, May 18, 2004 2:21 PM
To: XACML TC
Subject: [xacml] summary of Frank's delegation proposal
For people who could not make the F2F, I thought I would
summarize Frank Siebenlist's proposal for delegation. I was
pretty excited by it, and this it may be a good approach. I
apologize to Frank if I am mis-representing his proposal!
1. Associate an Issuer with each XACML policy that is visible to
the PDP (i.e. not just in a SAML Policy Assertion).
A new, optional <Issuer> element would be added as a child of
<Policy> and <PolicySet> to contain the Issuer identity. The
semantics of <Issuer> are that the named identity "says" that
the <Policy> or <PolicySet> in which it appears is an approved
policy of that identity. If the element is missing, the
Issuer is by default the PDP itself.
2. Allow an Issuer identity to declare that some other identity
has the right to issue policies of a given form.
The other identity is specified by a Subject with a new
SubjectCategory meaning "can issue".
3. An additional step is added to policy evaluation to find a
chain of applicable policies such that Issuer = PDP.
a. If the applicable policy has Issuer = PDP, then stop and
return the result of evaluating that policy. If there are
no applicable policies, return "Not Applicable".
b. Otherwise, for each applicable policy, create a new Request
equal to the original request except that it has an
additional <Subject> with SubjectCategory="delegate" and
subject-id equal to the Issuer of the applicable policy.
c. Find all policies applicable to the new Request. If any
result in "Permit", repeat starting with 3a.
Simple Example:
Policies are:
I is "Issuer"
D is a Subject with SubjectCategory="delegate"
S is a Subject with SubjectCategory="access-subject"
1. I=PDP
Permit Subject D="Manager1" to do Actions A to Resource R
2. I=Manager1
Permit Subject S=Manager2 to do Action A to Resource R
ROUND 1:
Request: Can Subject Manager2 do Action A to Resource R?
Policy 2 applies, and result is Permit, but Issuer is not PDP.
ROUND 2:
New Request: Can Subjects D=Manager2 and S=Manager2 do Action A
to Resource R?
Policy 1 applies, result is Permit, and issuer is PDP. Return
Permit.
Notes:
Policies that include SubjectCategory="delegate" could be
constructed to limit the set of applicable Subjects with
SubjectCategory="access-subject", could apply to many
delegates, could apply to many resources and actions, etc.
This delegation chain is only one policy long, but there could
be long chains.
Policies might mix delegation permissions with non-delegation
permissions. For example, some rules might apply to a
particular Subject with SubjectCategory="delegate", whereas
others might apply only to access-subject Subjects. A single
rule could apply to a mixture.
Things we did not finish thinking through (or that I did not hear
conclusions to):
- Do all chains have to be evaluated every time, or is there some
caching that could be done? PDP could have limit on how long a
chain could be and could test for cycles.
- How are the new policies issued by entities other than the PDP
inserted into the policy evaluation? Could they be passed
along with a Request, and possibly limited to use with that one
Request? Is there some new PDP API?
- How do "Deny" policies fit into this model?
- Are any new combining algorithms useful or required?
Anne
--
Anne H. Anderson Email: Anne.Anderson@Sun.COM
Sun Microsystems Laboratories
1 Network Drive,UBUR02-311 Tel: 781/442-0928
Burlington, MA 01803-0902 USA Fax: 781/442-1692
To unsubscribe from this mailing list (and be removed from the roster of the OASIS TC), go to http://www.oasis-open.org/apps/org/workgroup/xacml/members/leave_workgroup.php.
[Date Prev]
| [Thread Prev]
| [Thread Next]
| [Date Next]
--
[Date Index]
| [Thread Index]
| [List Home]