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  • VOS.ValWhatWhyHow(Last) -- DAVWikiAdmin? , 2017-06-29 07:35:32 Edit WebDAV System Administrator 2017-06-29 03:35:32

    Virtuoso Authentication Layer (VAL) - What, Why and How

    What Is the Virtuoso Authentication Layer (VAL)?

    VAL, the Virtuoso Authentication Layer, is an open-standards-based, multi-protocol authentication layer, that provides fine-grained, attributed-based access controls (ABAC) to protected resources (HTTP-accessible documents, folders, services [via their endpoints], and SPARQL named graphs). In a nutshell, this solution uses logic, expressed in the form of entity relationships, to address issues such as identity, authorization, and restriction.

    The key components of this solution are:

    Collectively, the components above enable:

    • Unambiguous Naming
    • Identity Claims Construction
    • Identity Claims Verification
    • Resource Access Rules (Authorizations) Creation and Evaluation
    • Resource Access Rate Rules (Restrictions) Creation and Evaluation

    Why Is VAL Important?

    As access to data grows across users, private networks, public networks, and hybrid network dimensions, there is an ever-increasing demand for controlled access to this data, in a manner that covers a variety of operational and social dimensions. It is no longer feasible to secure data using naive literal identification that doesn't attend to entity relationship realities reflected in the nature of different kinds of entity relationships.

    How Do I Use VAL?

    Prerequisites

    • Virtuoso Commercial Edition Instance
    • Virtuoso Authentication Layer (VAL) add-on module installation
    • Virtuoso Faceted Browser — optional; recommended for verification and troubleshooting
    • X.509 Certificates for Agents (Virtuoso Web Server and Client Software [e.g., SSH, HTTPS, ODBC, JDBC, ADO.NET applications]) that will communicate over TLS
    • X.509 Certificates for Application Users ? optional; not necessary whn Identity Delegation is in use

    Authorization Scoping

    Every resource type protected by VAL is associated with a distinct ACL scope. Examples include:

    • Sponger - for the Virtuoso Sponger Middleware Layer
    • SpongerCartridges - for specific Sponger Cartridges (for finer granularity control of access to the Sponger)
    • Query - for Query Services (SPARQL or SQL)
    • WebDAV - for all folders and documents accessible via WebDAV or Linked Data Profile (LDP) protocols
    • OAuth - for OAuth protocol
    • Private Named Graphs -- for internal RDF documents controlled by the Virtuoso Quad Store
    • Basic Entity Description Services
    • Advanced Faceted Browsing based Entity Description Services
    • PivotViewer Data Visualization
    • URI Shortener
    • Custom Scopes created for custom applications

    Virtuoso Realms

    As a hybrid data server, Virtuoso provides access to data across two distinct (but interlinked) functionality realms: HTTP and SQL. Thus, configuring VAL requires creation of Authorization and Restrictions rules that target each of the aforementioned realms, individually.

    VAL Authorizations apply to HTTP and/or SQL realms distinctly. Basically, you have an ACL Scope by Virtuoso Realms matrix per basic unit of ABAC functionality.

    Conductor's VAL Configuration UI

    Creating an ABAC ACL

    You achieve this by writing a collection of RDF language statements to a special VAL system named graph. These statements describe an instance of an authorization, and where additional restrictions apply they are also used to describe resource usage rate restrictions.

    Example of ABAC ACL


    ## Declaring an Authorization granting read-access to the named graph identified by the IRI 
    ## <OpenPermID-bulk-assetClass-20151111_095807.ttl.gz>
     
    SPARQL
    PREFIX  oplacl:  <http://www.openlinksw.com/ontology/acl#>
    PREFIX     acl:  <http://www.w3.org/ns/auth/acl#>
    
    WITH
       <http://linkeddata.uriburner.com/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23DefaultRealm>
    INSERT
       {
         <#PrivateNamedGraphRule1> 
           a                     acl:Authorization ;
           foaf:maker            <http://kingsley.idehen.net/dataspace/person/kidehen#this> ;
           oplacl:hasAccessMode  oplacl:Read ;
           acl:accessTo          <OpenPermID-bulk-assetClass-20151111_095807.ttl.gz> ;
           acl:agent             <https://s3.amazonaws.com/webid-sandbox/Profile/Basic-Identity-Claims-And-Profile-Document.ttl#i> ;
           oplacl:hasScope       oplacl:PrivateGraphs ;
           oplacl:hasRealm       oplacl:DefaultRealm .
      };
    

    Protecting an HTTP Realm (aka DefaultRealm) Service

    To protect HTTP Services provided by a Virtuoso instance such as: SPARQL endpoints, WebDAV and LDP file systems, Faceted Browsing, Sponger Entity Description Pages, PivotViewer, URL Shortener, and SPARQL/SQL Interactive Query Builder, etc., you need create the following:

    1. Describe your ACL using RDF Statements based on terms from the <http://www.w3.org/ns/auth/acl#>, <http://www.openlinksw.com/ontology/acl#>, and <http://www.openlinksw.com/ontology/restrictions#> vocabularies.
    2. Load your ACLs to the Virtuoso Quad Store hosted VAL system named graph using one of the following:
      • Virtuoso's RDF document loader
      • SPARQL
      • SPARQL inside SQL - via Conductor or command-line ISQL interfaces.
    3. Test your ACL

    Troubleshooting ACLs on HTTP Realm

    If your ACL doesn't perform as expected please check the following:

    • Your desired ACL scope is enabled - this will be visible via the Conductor Configuration URI for VAL or it can be looked up via its HTTP URI using the Faceted Browser or SPARQL.
    • The enabled ACL scope is associated with the DefaultRealm - this is what binds an ACL to the HTTP functionality realm and this will be visible via the Conductor Configuration UI for VAL or it can be lookedup via its HTTP URI using the Faceted Browser or SPARQL.

    Protecting a SQL Realm (aka SqlRealm) Service

    To protect SQL Services provided by a Virtuoso instance (e.g., ODBC, JDBC, ADO.NET, OLE-DB connectivity and access; SPASQL (SPARQL inside SQL); etc.), you need to take the following steps:

    1. Create RDF statements, based on terms from the <http://www.w3.org/ns/auth/acl#>, <http://www.openlinksw.com/ontology/acl#>, and <http://www.openlinksw.com/ontology/restrictions#> vocabularies, that describe each of the following
      • a SQL Realm access authorization, for example —

        -- SQLRealm ACL -- Cleanup SPARQL PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> PREFIX acl: <http://www.w3.org/ns/auth/acl#> WITH <http://id.myopenlink.net/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm> DELETE { <#WebIDTLSSQLAccessRule1> ?p ?o . }; -- ACL Definition -- SQL Access Privileges Grant to a Specific WebID -- SPARQL PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> PREFIX acl: <http://www.w3.org/ns/auth/acl#> PREFIX foaf: <http://xmlns.com/foaf/0.1/> WITH GRAPH <http://id.myopenlink.net/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm> INSERT { <#WebIDTLSSQLAccessRule1> a acl:Authorization ; foaf:maker <http://kingsley.idehen.net/dataspace/person/kidehen#this> ; rdfs:label "SQL Realm Access Authorization ACL" ; rdfs:comment """Mandatory ACL for granting access to SQL Realm which then enables ODBC, JDBC, ADO.NET, OLE-DB compliant application access, subject to Agent & User Identity.""" ; oplacl:hasAccessMode oplacl:Read ; acl:accessTo <urn:virtuoso:access:sparql> ; acl:agent <http://id.myopenlink.net/dataspace/person/kidehen#this> , <http://kingsley.idehen.net/dataspace/person/kidehen#this> , <https://s3.amazonaws.com/webid-sandbox/Profile/Basic-Identity-Claims-And-Profile-Document.ttl#i> , <http://kingsley.idehen.net/public_home/kidehen/profile.ttl#i> , <https://dbfff61d85d4da9b5aefce09723385e78a93f731.googledrive.com/host/0B-Mx14cLTEsaczdJdk96UVQ0aVE/profile.ttl#identity> ; oplacl:hasScope oplacl:Query ; oplacl:hasRealm oplacl:SqlRealm . };

      • a SQL Realm usage rate per second restriction, for example —

        -- SQL Query Access Restrictions (SQLRealm re. ODBC, JDBC, ADO.NET) -- -- Query Request Rate -- Cleanup SPARQL PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> PREFIX acl: <http://www.w3.org/ns/auth/acl#> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX oplrest: <http://www.openlinksw.com/ontology/restrictions#> WITH GRAPH <http://id.myopenlink.net/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm> DELETE { <#IDMyOpenLinkTLSSQLAccessRestriction1> ?p ?o . }; -- Restriction Definition SPARQL PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> PREFIX acl: <http://www.w3.org/ns/auth/acl#> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX oplrest: <http://www.openlinksw.com/ontology/restrictions#> WITH GRAPH <http://id.myopenlink.net/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm> INSERT { <#IDMyOpenLinkTLSSQLAccessRestriction1> a oplrest:Restriction ; foaf:maker <http://kingsley.idehen.net/dataspace/person/kidehen#this> ; rdfs:label "SQL Realm Query Rate Restriction" ; rdfs:comment """Mandatory Restriction for metering Query Request Rates per second.""" ; oplrest:hasRestrictedResource <urn:virtuoso:restrictions:sql-request-rate> ; oplrest:hasMaxValue "100"^^xsd:integer ; acl:agent <http://id.myopenlink.net/dataspace/person/kidehen#this> , <http://kingsley.idehen.net/dataspace/person/kidehen#this> , <https://s3.amazonaws.com/webid-sandbox/Profile/Basic-Identity-Claims-And-Profile-Document.ttl#i> , <http://kingsley.idehen.net/public_home/kidehen/profile.ttl#i> , <https://dbfff61d85d4da9b5aefce09723385e78a93f731.googledrive.com/host/0B-Mx14cLTEsaczdJdk96UVQ0aVE/profile.ttl#identity> ; oplacl:hasRealm oplacl:SqlRealm . };

      • a SQL Realm Max Rows per query result set [solution] restriction, for example —

        -- Query Results Size -- Cleanup SPARQL PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> PREFIX acl: <http://www.w3.org/ns/auth/acl#> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX oplrest: <http://www.openlinksw.com/ontology/restrictions#> WITH GRAPH <http://id.myopenlink.net/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm> DELETE { <#IDMyOpenLinkTLSSQLAccessRestriction2> ?p ?o . }; -- Restriction Definition SPARQL PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> PREFIX acl: <http://www.w3.org/ns/auth/acl#> PREFIX foaf: <http://xmlns.com/foaf/0.1/> PREFIX oplrest: <http://www.openlinksw.com/ontology/restrictions#> WITH GRAPH <http://id.myopenlink.net/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm> INSERT { <#IDMyOpenLinkTLSSQLAccessRestriction2> a oplrest:Restriction ; foaf:maker <http://kingsley.idehen.net/dataspace/person/kidehen#this> ; rdfs:label "SQL Realm Resultset [Query Solution] Size Restriction" ; rdfs:comment """Mandatory Restriction for restrictng maximum size of query resultsets [solutions].""" ; oplrest:hasRestrictedResource <urn:virtuoso:restrictions:sql-result-rows> ; oplrest:hasMaxValue "200"^^xsd:integer ; acl:agent <http://id.myopenlink.net/dataspace/person/kidehen#this> , <http://kingsley.idehen.net/dataspace/person/kidehen#this> , <https://s3.amazonaws.com/webid-sandbox/Profile/Basic-Identity-Claims-And-Profile-Document.ttl#i> , <http://kingsley.idehen.net/public_home/kidehen/profile.ttl#i> , <https://dbfff61d85d4da9b5aefce09723385e78a93f731.googledrive.com/host/0B-Mx14cLTEsaczdJdk96UVQ0aVE/profile.ttl#identity> ; oplacl:hasRealm oplacl:SqlRealm . };

    2. Load your ACLs to the Virtuoso Quad Store hosted VAL system named graph using one of the following:
      • Virtuoso's RDF document loader
      • SPARQL
      • SPARQL inside SQL - via Conductor or command-line ISQL interfaces.
    3. Test your ACL

    Troubleshooting ACLs on SQL Realm

    If your ACL doesn't perform as expected, please check the following:

    • Existence of an Authorization - You can look up the existence of your Authorization via its HTTP URI using the Faceted Browser or SPARQL.
    • Existence of a Restriction - You can look up the existence of your Restriction via its HTTP URI using the Faceted Browser or SPARQL.
    • Your desired ACL scope is enabled - this will be visible via the Conductor Configuration UI for VAL or it can be looked up via its HTTP URI using the Faceted Browser or SPARQL.
    • The enabled ACL scope is associated with the DefaultRealm - this is what binds an ACL to the HTTP functionality realm and will be visible via the Conductor Configuration UI for VAL or it can be looked-up via its HTTP URI using the Faceted Browser or SPARQL.

    Further Reading