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EU Data. Grid and Grid. PP Authorization and Access Control Andrew Mc. Nab, University EU Data. Grid and Grid. PP Authorization and Access Control Andrew Mc. Nab, University of Manchester [email protected] man. ac. uk Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Outline u EDG Testbed Overview u Globus Security u Sysadmins’ u Existing u Pool Outline u EDG Testbed Overview u Globus Security u Sysadmins’ u Existing u Pool issues VO accounts u LCAS/LCMAPS Site Access Control u VOMS u Slash. Grid u Grid. Site u Grid ACL’s u Future Grid. PP / EDG / WP 6 developments Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Existing EDG Testbed Currently ~300 users at ~20 sites across Europe Grid. PP / Existing EDG Testbed Currently ~300 users at ~20 sites across Europe Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Globus Security u EDG currently uses Globus 2 gatekeepers and file servers, and Globus’s Globus Security u EDG currently uses Globus 2 gatekeepers and file servers, and Globus’s GSI model for authentication. u Users and hosts are identified by X. 509 certificates, signed by one of ~17 “national” Certificate Authorities n n CA policy statement must be acceptable to EDG CA Group CA root certs/configuration distributed by same channels as bug fixes, security patches etc. u Users can produce delegated credentials (“GSI proxy”) by signing a public key with their user certificate n this can be chained to delegate credentials to remote servers u Authorization is provided by simple text file with certificate names and corresponding local Unix account names. n /etc/grid-security/grid-mapfile consisting of lines like: “/O=Grid/O=UKHEP/OU=hep. man. ac. uk/CN=Andrew Mc. Nab” mcnab Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Testbed site administrators’ initial worries. . . u How can Grid users gain access Testbed site administrators’ initial worries. . . u How can Grid users gain access without me creating new accounts every day? u How can I limit what they can do? u How can I audit what they’ve done to me? u How can I keep track of files they’ve created? u Local access control and account management usually boils down to n n Grid. PP / EDG / WP 6 mapping Grid identities into appropriate local Unix identities while respecting the above. Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Existing EDG LDAP VO u EDG currently uses Virtual Organisation authorisation servers: centrally provided Existing EDG LDAP VO u EDG currently uses Virtual Organisation authorisation servers: centrally provided authorisation listings n published via LDAP (~300 users in ~10 VO ’s) n mkgridmap tool for building local grid-mapfile with local choice of VO ’s. n GUI tools allow VO managers to manage VO membership u Provides a list of certificate DN’s for a given group: eg an experiment, or a group within an experiment. u Groups n have to be defined by an admin of the VO can’t be defined on ad-hoc basis by small groups of users u Will eventually meet scaling issues since each site must frequently (daily? ) fetch listings for VO ’s it accepts. n VOMS or CAS “visa” model would help a lot with this Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Joining an application VO u Users first join the Acceptable Use Policy VO, with Joining an application VO u Users first join the Acceptable Use Policy VO, with their web browser, using their certificate n n this involves agreeing to the Data. Grid wide AUP, that sets out obligations of sites and users legal wording done in conjunction with CERN legal experts (who understandably have a lot of experience of international law) u Users can then join the VO of their application (eg an LHC experiment) n VO manager can choose whether to accept user u At each site, AND of AUP VO and Application VO controls access Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Pool accounts u The n other half of removing account creation burden from admins Pool accounts u The n other half of removing account creation burden from admins pre-create pools of accounts and allocate these to users when they request access u Widely n used by EDG Testbed sites, but not obligatory in practice, almost all have chosen to use it u Auditing possible since all DN=>UID mappings recorded in log files. u Same pool mappings can be shared across a farm by sharing /etc/grid-security/gridmapdir/ lock files with NFS. u Existing n n system works ok for CPU-only jobs. but not really appropriate if users are creating long lived files at the site in question. limitations are because files are still owned by Unix UID: can’t recycle UID until all files created have been removed. Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

LCAS / LCMAPS site access u Extension of Globus access control / mapping u LCAS / LCMAPS site access u Extension of Globus access control / mapping u LCAS - provides site-specific callouts to check authorisation based on user identity, what is requested, quotas, free-slots in batch system etc. n n n currently implemented as patched Globus gatekeeper, plus plugins to enforce policies allows sites to implement complex, locally defined rules for access, including locally written extensions to check site-specific features (eg load on locally written tape-library service) some of this functionality will also be provided by recent Globus proposal for authorisation callouts (but currently limited to yes/no on identity? ) u LCMAPS - manages current mappings of Grid to local identity n makes this available to other local site components n important when not just using a simple, shared grid-mapfile for mapping Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Virtual Organisation Membership Service: VOMS u Instead of publishing lists of VO and group Virtual Organisation Membership Service: VOMS u Instead of publishing lists of VO and group membership, supply signed attribute certificates to users. u Users can then present these attribute certificates to sites/resources and obtain access with group privilege, role etc. u Certificates can be included in GSI proxy certificates as extensions u Multiple attribute certificates can be used simultaneously, even from different VOMS servers and VOs. u Potential to allow users to create ad-hoc groups within VO, and to discard unnecessary VOMS credentials at delegation steps. u This n is similar to Globus’s Community Authorization Service (CAS) however, VOMS is designed for maximum backwards compatibility and to maintain the user as the verifiable and principle source of authentication Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Slash. Grid / certfs / curlfs u Framework n for creating “Grid-aware” filesystems different Slash. Grid / certfs / curlfs u Framework n for creating “Grid-aware” filesystems different types of filesystem provided by dynamically loaded (and potentially third-party) plugins. u certfs. so plugin provides local storage governed by Access Control Lists based on Grid certificate name’s and VO groups n certfs is very solid: you can build a bootable Linux kernel on a certfs filesystem (~100, 000 file operations in a few minutes) u Since new ACL’s just have creator’s name, this is equivalent to file ownership by certificate name rather than UID. n n solves admin worries about long lived files owned by pool accounts. if pool accounts are prevented from writing to normal disks, then no chance they will write something unpleasant somewhere unexpected. u HTTP/HTTPS plugin (curlfs) ultimately aims to provide some NFS/AFS-like functionality, again governed by Grid creds + ACL’s. Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Slash. Grid as container environment u Basic Slash. Grid use maps area like /var/spool/slashgrid/xxx Slash. Grid as container environment u Basic Slash. Grid use maps area like /var/spool/slashgrid/xxx to /grid/xxx, with mapping controlled by plugin code. u But also allows virtual directory hierarchies which don’t correspond to real areas on disk n “gridmap” plugin, populated with symbolic links: eg /grid/p/atlas 001 -> /grid/u/O=Grid/O=UKHEP/OU=hep. man. ac. uk/CN=Andrew%20 Mc. Nab u Could go further and create whole user environments on demand n can be a “sandbox” if we prevent operations outside this environment n can be tailored to user’s application (eg default shared library versions) u This means we could achieve a lot of the security and uniformity between sites that, say, a Java VM has, but with native binaries. u This would be very complementary to new GT 3 GRAM and execution environment factory. Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Current ACL’s u When building Grid. Site, Slash. Grid and the EDG Storage Element, Current ACL’s u When building Grid. Site, Slash. Grid and the EDG Storage Element, we needed a simple ACL format to use for prototyping. u Current n n Slash. Grid and Grid. Site use per-directory XML ACL in. gacl As a file, this can be stored in directories, copied via unmodified https or gsiftp channels and easily manipulated by scripts and applications. Sysadmins want disk filesystem ACL’s on same physical disk as files if possible (or managed off-site!) u Implementing ACL’s also solves some other Grid vs Unix issues that emerged during with Testbed: n eg per-UID tape storage: can store all tape files with one UID but associate ACL with the file and use that. u Clearly, isn’t a recognised standard, and we could go to, say, a subset of XACML: however, things like filesystems are very performance sensitive. Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Current ACL format <gacl version=“ 0. 0. 1”> <entry> <dn-list> <url>ldap: //ldap. abc. ac. Current ACL format ldap: //ldap. abc. ac. uk/ou=xyz, dc=abc, dc=ac, dc=uk /O=Grid/OU=abc. ac. uk/DN=Abc. VOMS Abc readers /O=Grid/DN=Andrew Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Grid ACL vs fine-grained VO: CAS, VOMS etc u CAS or VOMS can provide Grid ACL vs fine-grained VO: CAS, VOMS etc u CAS or VOMS can provide ACL-like feature, specifying what capability (“write”) is permissible on objects (“higgs-wg-montecarlo”) n In some cases, this could be used to provide ACL functionality. u However, we think this is too coarse-grained and too heavyweight for all contexts n eg if my job creates a temporary, working directory in /grid/tmp, I don’t want to have to set up a new entry on the central CAS or VOMS machine u The n n n two types of system should be seen as complementary when you create some Higgs Monte Carlo data, you set its ACL to give write access for people with “higgs-wg-montecarlo-admin” credential. when you create a temporary working directory, you set its ACL to give only you read and write access. applications should “find their own level” when splitting policy between local ACL or VO-wide authorisation service Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

GACL library u XML ACL format not finalised but have several products in use GACL library u XML ACL format not finalised but have several products in use which need to use it: Grid. Site; Slash. Grid; and EDG Storage Element. u ACL will almost certainly change again in the future; and may need to understand different ACL’s (eg XACML? ) from other projects. u Insulate ourselves from this by putting ACL handling functions into a standalone library, and make this understand the current XML. u Handles read/list/write ACL’s in a reasonably general way n packs C structs and linked lists with their contents n provides access functions to manipulate the structs as new types. u Despite current C implementation, API is readily translatable to object-orientated languages n Java API and implementation being produced Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Grid. Site u Grid. Site manages access to websites and HTTP(S) fileservers n Users Grid. Site u Grid. Site manages access to websites and HTTP(S) fileservers n Users and admins load GSI cert + key into unmodified web browsers n Originally produced for www. gridpp. ac. uk u ACL’s n control level of read and write access to file/directory Write access by HTML forms (interactive) or HTTP PUT (programmatic) u Website admins can define groups of users with specific rights n Can delegate administration of that group to one or more members. n Group membership can also be published in EDG VO LDAP format. u New 0. 9 architecture also provides support for efficient HTTP GET and PUT operations via Apache module. n ACL enforcement now available for PHP, CGI, JSP etc as well as HTML u Grid. Site used by several external projects, including e-Science Level 2 Grid support website. Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Grid. Site 0. 9 architecture grst-admin. cgi: page editing, file upload, ACL editing etc. Grid. Site 0. 9 architecture grst-admin. cgi: page editing, file upload, ACL editing etc. mod_gridsite: . html headers and footers . shtml, mod_perl CGI, PHP grst-proxy. cgi: G-HTTPS, 3 rd party COPY, proxy GET + PUT mod_jk: JSP with Tomcat mod_gridsite: PUT, DELETE, MOVE mod_gridsite: GACL access control + GACL > env vars HTTP Grid. PP / EDG / WP 6 mod_ssl: plain HTTPS > env vars mod_ssl-GSI: HTTPS with GSI+VOMS+CAS > env vars Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Future Developments u EU n n n Data. Grid officially finishes 31 st Dec Future Developments u EU n n n Data. Grid officially finishes 31 st Dec 2003 EGEE is an EU Framework 6 proposal to deploy an EU-wide Grid, largely using EDG technology for HEP, Bioinformatics and other e-Science. Grid. PP comes to an end in 2004, and Grid. PP-2 proposal is being drafted for PPARC e-Science 2 nd Phase. CERN is also sponsoring the LHC Computing Grid to deploy a Grid for High Energy Physics. u All of these projects stress deployment and operations rather than middleware development. u However, development of Accounting and Usage Control mechanisms is acknowledged as essential to running these production services. u We propose to extend Grid. PP Authorization work into Accounting, and to collaborate with e-Science NW / MC expertise in this area. Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003

Summary u Most of the concerns of Testbed site admins are being addressed u Summary u Most of the concerns of Testbed site admins are being addressed u LDAP VO system is currently sufficient, but VOMS or CAS would be more flexible and scalable. u Pool accounts are useful but limited by UID file ownership issues. u Slash. Grid / certfs provides a solution to this. u LCAS/LCMAPS u Grid. Site u GACL allow flexible, locally configurable site policies. provides a way of controlling HTTP(S) via Grid credentials. library provides API for handling Grid ACL’s. u Extending work into Usage Control, not just Access Control. u See http: //www. gridpp. ac. uk/authz/ for links to source code and details of all tools mentioned in this talk Grid. PP / EDG / WP 6 Andrew Mc. Nab - EDG Access Control - 13 Mar 2003