Building the GENI Federation With ABAC

1. Building the GENI Federation With ABAC Jeff Chase Duke University Thanks: NSF TC CNS-0910653

2. Reading the slides GENI users Test Tube Guy and Dr. D, and some of their credentials T D A A generic principal IdP.studentT IdP.facultyD A coordination service implementing some clearinghouse function, such as a Slice Authority AM SA Indicates trust of one principal in another, often associated with some kind of formal agreement: Indicates a request Aggregate Indicates credential flow

3. GENI trust structure: overview (v1.0) Users and tools Users create global slices and request aggregates to bind local resources to those slices. GENI Federation Oversight Bidirectional trust based onagreements AM AM AM AM CH Principals are users and organizations, and tools or servers acting on their behalf.

4. GENI trust structure: overview (v2.0) GENI “clearinghouse” • Each of these entities may: • Speak with its own keypair. • Wield credentials. • There are limited trust relationships among them. • Trust reflects agreements, and is limited by their scope. • Credentials capture this trust. • Trust may be transitive. GOC IdP GMOC PA SA I&M AMs trust the coordination services, transitively. AM AM Nothing has really changed, but we have named some of the CH coordination services, and introduced a federation root (GOC) to endorse federation-affiliated services. See the intro slide deck.

5. Reasoning about trust graphs • This is a trust graph. • Edges represent limited trust by source entity in the target. • We can capture trust graphs in a delegation logic. • Some out-edges are facts given by an entity’s local operator. • The others are inferred locally by applying locally accepted policy rules to facts. GOC IdP GMOC PA SA I&M AM AM Given a suitable trust management framework (e.g., ABAC), trust delegations and policies for inferring trust (by finding trust paths) may be specified declaratively and checked automatically.

6. Overview • Walk through the GENI trust graph step by step. • Show how to represent it in ABAC. • Familiarity with ABAC (RT0 delegation logic) is assumed. There is another slide deck on that. • Walk through a canonical GENI example of a sequence of requests through the trust graph. • For each step in the sequence, give examples of authorization policies represented in ABAC. • Show how automated policy checking combines the policies of multiple “coordinator” entities. • PA, SA, AM

7. GOC endorses GENI services GOC.sliceAuthoritySA GOC.projectAuthorityPA GOC.idpIdP GOC.aggregateAM • These endorsements are facts asserted by GOC under its key. • Each fact endorses another entity’s key for some role. • An endorsement may be based on an agreement or on trust in an entity’s controlling domain. GOC IdP GMOC PA SA I&M Common CH domain agreements AM AM These endorsements by GOC are credentials that are visible to other entities, and may lead those entities to infer transitive trust.

8. Coordinators in the federation • Each coordinator C has a local fact naming the federation root. • For C in {IdP, PA, SA} • Typical policy rules at C might tell C to trust root endorsements of other federation services. C.rootGOC GOC IdP GMOC PA SA I&M Sample policy rules for each coordinator C: C.sliceAuthority(C.root).sliceAuthority C.projectAuthority(C.root).projectAuthority C.idp(C.root).idp C.aggregate(C.root).aggregate I believe whatever the root tells me about other services in this federation.

9. Aggregates join the federation • Each AM has a local fact for its trust in the federation root. • Typical AM policy rules might trust the root’s endorsements of coordinators and perhaps other aggregates. AM.rootGOC GOC AMs trust the coordination services, transitively. inferred trust AM AM Sample AM policy rules: AM.sliceAuthority(AM.root).sliceAuthority AM.projectAuthority(AM.root).projectAuthority AM.idp(AM.root).idp

10. Filling in the trust structure • These sample policy rules define sets of valid trust paths. • A trust path indicates inferred trust by the source entity in the destination entity. GOC IdP GMOC PA SA I&M Inferred facts: AM.sliceAuthoritySA AM.projectAuthorityPA AM.idpIdP C.aggregateAM C.sliceAuthoritySA C.projectAuthorityPA C.idpIdP for each coordinator C in {IdP, PA, SA} Inferred trust bidirectional AM Aggregates and coordinators trust one another.

11. GOC Register user Create project Create slice in x 3 2 1 4 5 Project x created Slice s created user registered PA IdP SA Issue slice credentials Issue project credentials Issue user credentials AM Users have roles e.g., student, faculty. Delegate project credentials Create sliver in in s

12. Identity Portal/Provider (IdP) • An IdP asserts facts about users. • User attributes may include inCommon attributes harvested through indirect delegation to Shibboleth IdPs. • These attributes may have parameters with simple values (strings or numbers). Register user user registered IdP Issue user credentials The delegation logic should support parameterized attributes (e.g., RT1). T IdP.geniUserT IdP.studentT IdP.enrolled(CS-114)T Users have roles e.g., student, faculty. D IdP.geniUserD IdP.facultyD

13. Authorization Register user Create project Create slice in x 5 3 2 1 4 Verify that project x is valid and user is authorized to create slice s in project x. Verify user identity, obtain attributes, check that user is qualified, execute agreement. Verify that user is authorized to create project and act as project leader. IdP SA PA Create sliver in in s AM Delegate project credentials Verify that slice s is valid and user is authorized to request resources for s.

14. Guards • Before a server executes a request, it checks it for compliance with an authorization policy. • The policy is implemented by a guard: a predicate that must be satisfied (i.e., evaluate to true). • A guard may itself be a conjunction of predicates. • These predicates are also guards: they must all be satisfied to allow the operation. request G1 AND G2 AND G3 Guard Client Server Request r on object x reference monitor Guard for r(x): a conjunction of predicates

15. Representing guards • We introduce some new syntax for guards. • If a coordinator C creates an object x, call the object by the global name C.x. • E.g., project PA.x and slice SA.s • For operation request r on an object x created by a coordinator C, state the guards in sequence: G1: r(C.x): <predicate 1> G2: r(C.x): <predicate 2> … GN: r(C.x): <predicate N> G1 <predicate 1> AND G2 <predicate 2> AND G3 <predicate 3>

16. Guards and ABAC • A guard predicate is typically an ABAC role or attribute that can be checked automatically by an inference engine. • We break them out so that we can talk about them separately without writing down the conjunctions (long ABAC “type 4” rules). • Also, we want to allow more general guards whose predicates are evaluated outside of ABAC. • Or guards that generate an ABAC query “on the fly” from a template, based on other info in the request. • Or guards that modify the request, e.g., degrade the class of service if a particular credential is missing. • More on all this later… r(C.x) G1 <predicate 1> AND G2 <predicate 2> AND G3 <predicate 3>

17. Project Authority (PA) GOC • Project Authority has policies for who can create a project. • For each new project x (global name PA.x), PA issues facts and policy rules defining powers and rights of x and how they can be delegated. User credentials for Dr. D Create project PA Sample guards for creating a project G1:createProject: (PA.idp).faculty G2:createProject: (PA.idp).geniUser Project x created Issue project credentials Sample policy rules for project x PA.in_x(PA.leader_x).in_x PA.createSliceFor_xPA.in_x D PA.leader_xD

18. PA policies: a closer look Sample guards for creating a project G1:createProject: (PA.idp).faculty G2:createProject: (PA.idp).geniUser Any approved GENI user who is also a faculty member can create/lead a project. Sample policy rules for project x G1: in_x: (PA.leader_x).in_x G2: in_x: (PA.idp).geniUser G1: createSliceFor_x: PA.in_x Your policies may vary. PA Project Authority may customize these rules on a per-project basis. PA generates them from a template when it creates project PA.x. The project leader may delegate membership in the project to any GENI user. Any project member may create a slice for the project.

19. Slice Authority (SA) GOC • SA has policies for who can create/register a slice for use at affiliated aggregates. • For each new slice s (global name SA.s), SA issues facts and policy rules defining powers and rights of s and how they can be delegated. Create/register slice SA Slice s created Sample policy rules for a slice s G1:createSliver_s: SA.creator_s Issue slice credentials T Sample guards for creating a slice G1:createSliceFor(PA.x): SA.projectAuthorityPA G2:createSliceFor(PA.x): PA.createSliceFor_x SA.creator_ST

20. SA policies: a closer look Sample guards for creating a slice G1:createSliceFor(PA.x): SA.projectAuthorityPA G2:createSliceFor(PA.x): PA.createSliceFor_x Anyone can create a slice for a project PA.x if x was approved by a Project Authority I trust, and the request conforms to project policies. Your policies may vary. Sample policy rules for a slice s G1:createSliver_s: SA.creator_s SA Only the creator of a slice s may create a sliver for s. Slice Authority may customize these rules on a per-slice basis. SA generates them from a template when it creates slice SA.s. Later we’ll consider how to represent more flexible policies for slices, e.g., SFA capabilities supplemented with GENI safety restraints.

21. Example: createSlice authorization Approved SA.createSliceFor(PA.x)T Create project SA.creator_sT SA authorization policy G1:createSliceFor(PA.x): SA.projectAuthorityPA G2:createSliceFor(PA.x): PA.createSliceFor_x Project x created PA.leader_xD PA SA D Create slice in PA.x PA policy for PA.x G1: createSliceFor_x: PA.in_x G1: in_x: (PA.leader_x).in_x G2: in_x: (PA.idp).geniUser D.in_xT T IdP.geniUserT

22. Example: createSliver authorization Approved AM.createSliver(SA.s)T AM authorization policy G1:createSliver(SA.s): AM.sliceAuthoritySA G2:createSliver(SA.s): SA.createSliver_s Create sliver for slice s AM SA SA.creator_sT SA policy for SA.s G1:createSliver_s: SA.creator_s T Later we’ll consider more flexible policies for slices. IdP.geniUserT

23. Are we done yet? Not quite. • We would like to represent more flexible policies. • These policies are not fully specified for implementation in RT0 delegation logic. • We need roles with parameters (RT1), at least for inCommon user identity attributes. • And what are those funny embedded object names in roles like leader_x, in_x, and creator_s? • What are those object-valued parameters for guards like SA.createSliceFor(PA.x) and AM.createSliver(SA.s)? • Can AMs mix and match coordinators? What if there are multiple intertwined federations? • How to get the right credentials in the right place at the right time, safely?