Signed ClassAds and Restricted Delegation

1. Signed ClassAdsand Restricted Delegation Condor Week 2007

2. Condor Week 2007

3. Condor Week 2007 Security Issues in Multiple Administrative Domains • Multiple administrative domains aren’t well protected from each other, yet are increasingly common: Condor-C, Condor-G, flocking… • As cooperation between administrative domains increases, so does utilization. Can we take advantage of this without also increasing risk? Job input and output data Execute Machines Data unrelated to the job Protect:

4. Condor Week 2007 Shoulders of Giants Principle of least privilege: “Every program and every user of the system should operate using the least set of privileges necessary to complete the job.” - Saltzer and Schroeder, 1975

5. Condor Week 2007 Credential Scope • Jobs either carry no credentials or the full credentials of the submitting user. • Jobs with credentials can impersonate the submitting user without any restriction. • Intermediaries that handle credentials can lose or abuse them, or alter tasks, input, and results. Limit the scope of credentials to what the job needs and no more.

6. Condor Week 2007 Goals Make security assumptions explicit. Reduce the number and scope of assumptions that must be made about infrastructure w.r.t. security. Provide end-to-end security options in addition to point-to-point security. Provide end-to-end cryptographic audit. Alter attacker incentives. Reduce barriers to increased cooperation and utilization.

7. Condor Week 2007

8. Condor Week 2007 Participants U – submitting user S – scheduler X – execute host R – storage resource U S X R

9. s - submit f - forward e - execute a - access U – submitting user S – scheduler X – execute host R – storage resource Actions s e a U S X R Condor Week 2007

10. s - submit f - forward e - execute a - access U – submitting user S – scheduler X – execute host R – storage resource Forwarding Action s U S f e a S X R Condor Week 2007

11. U – submitting user S – scheduler X – execute host R – storage resource s - submit f - forward e - execute a - access Multiple Administrative Domains s U R S f e a S X R Condor Week 2007

12. U – submitting user S – scheduler X – execute host R – storage resource s - submit f - forward e - execute a - access Authentication /O=Brown CS/CN=pavlo GSI Proxy Certificates Mutual Authentication s U S f e a S X R /O=Penn CS/CN=scheduler.cs.penn.edu /O=Penn CS/CN=ex0001.cs.penn.edu /O=UMD CS/CN=storage.cs.umd.edu /O=Brown CS/CN=scheduler.cs.brown.edu Condor Week 2007

13. U – submitting user S – scheduler X – execute host R – storage resource s - submit f - forward e - execute a - access Authorization /O=Brown CS/CN=pavlo -> pavlo@cs.brown.edu s U S Recipient checks ACL f e a S X R Condor Week 2007

14. Condor Week 2007 Problems • Authorization entirely in the hands of the recipients: no restrictions can be expressed by the submitter. • Credential too permissive: can be used to access anything on resources, run any job on execute machine. • Unnecessary reliance on schedulers to preserve confidentiality and integrity of credentials. • No audit trail.

15. Condor Week 2007 Attackers • Incentive to attack schedulers; compromise results in full control: • Alter tasks (to attack execute hosts or cause them to attack external hosts). • Access resources using credentials. • Forge results returned to submitter.

16. Condor Week 2007 Signed ClassAds • ClassAds with digital signatures. • Signature made and checked using X.509 keys and certificates. • Altered ClassAds are easily detected. • External files can be referenced using checksums. • Explicit association between a task and information about its origin and provenance. • Results can be signed as well: receipts.

17. Condor Week 2007 TS Task-specific Proxy Certificates • Proxy certificates with embedded signed ClassAds. • Policy field in proxy certificate contains signed ClassAd for the associated job. • Proxy delegation chain inalterably linked with particular job.

18. Action Authorization Expressions • ClassAd language expressions included in the signed ClassAd. • Can specify conditions on actions that the proxy certificate might be used for: submit, forwarding, execute, and access. • Permits the submitting user to limit how their credentials are used. Condor Week 2007

19. U – submitting user S – scheduler X – execute host R – storage resource s - submit f - forward e - execute a - access Mutual Authorization /O=Brown CS/CN=pavlo U=/O=Brown CS/CN=pavlo S=/O=Brown CS/CN=sche… s(U,S) U=/O=Brown CS/CN=pavlo X=/O=Penn CS/CN=ex0001… R=/O=UMD CS/CN=storage… a(U, X R) U=/O=Brown CS/CN=pavlo Sa=/O=Brown CS/CN=sche… Sb=/O=Penn CS/CN=sche… f(U, Sa, Sb) U=/O=Brown CS/CN=pavlo S=/O=Penn CS/CN=sche… X=/O=Penn CS/CN=ex0001… e(U, S, X) s U S f e a S X R /O=Brown CS/CN=scheduler.cs.brown.edu /O=Penn CS/CN=scheduler.cs.penn.edu /O=UMD CS/CN=storage.cs.umd.edu /O=Penn CS/CN=ex0001.cs.penn.edu Condor Week 2007

20. Questions? For more information, contact: Ian Alderman alderman@cs.wisc.edu