SQL ACLs and Restrictions - Controlling SPARQL Access in SQL Data Connections

Introduction
Private Graphs used for ACL storage
Enabling SQL ACLs
ACL Restrictions to Control Request and Result Limits
Examples

Restriction Examples

Restrict The Request Rate
ACL Examples

Grant SPARQL Read Permissions to Anyone With a Valid Certificate
Grant SPARQL Sponge Permission to One Certificate

Grant SPARQL Write Permissions For One Private Graph To One Certificate
Grant SPARQL Write Permissions Based on a SPARQL ASK Query

See Also

Introduction

Virtuoso allows control over certain functionality in SQL data connections (ODBC, JDBC, ADO.NET, OLE DB, etc.) via ACLs. These ACLs mostly refer to SPARQL and match what is described in SPARQL ACLs.

The primary difference is the realm, which is oplacl:SqlRealm here.

Note: SPARQL ACL rules defined in the default realm do not apply in SQL connections!

There is also one additional resource, which simply allows users to perform SQL commands in addition to SPARQL: urn:virtuoso:access:sql. In theory, both oplacl:Read and oplacl:Write would apply, but these are not enforced yet. Either of them will currently enable all SQL commands.

Private Graphs used for ACL storage

The Rules can be controlled via the VAL ACL RESTful API or the Internal VAL API. Alternatively one can directly add the rules to the private graph matching the realm in which the rules should apply. Given the SQL realm http://www.openlinksw.com/ontology/acl#SqlRealm and default hostname "HOST" the graph IRIs would be:

ACL Rules: http://HOST/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm
Groups: http://HOST/acl/graph/groups/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm.
Restrictions: http://HOST/acl/restrictions/groups/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm.

Be aware that these graphs can be customized for better readability.

Enabling SQL ACLs

By default ACLs will not be enforced since the ACL scope is disabled. To enable general SPARQL ACL rules in the sql realm:

sparql
prefix oplacl: <http://www.openlinksw.com/ontology/acl#>
with <urn:virtuoso:val:config>
delete {
  oplacl:SqlRealm oplacl:hasDisabledAclScope oplacl:Query .
}
insert {
  oplacl:SqlRealm oplacl:hasEnabledAclScope oplacl:Query .
};

Similarly ACLs for individual private graphs are enabled via:

sparql
prefix oplacl: <http://www.openlinksw.com/ontology/acl#>
with <urn:virtuoso:val:config>
delete {
  oplacl:SqlRealm oplacl:hasDisabledAclScope oplacl:PrivateGraphs .
}
insert {
  oplacl:SqlRealm oplacl:hasEnabledAclScope oplacl:PrivateGraphs .
};

ACL Restrictions to Control Request and Result Limits

In addition to the ACL Rules to control who has the right to perform which actions Virtuoso allows to control certain limits via ACL Restrictions.

The following restriction resources are supported:

urn:virtuoso:restrictions:sql-request-rate - Limit the request rate in one SQL connection.
urn:virtuoso:restrictions:sql-content-size - Limit the result content size. This applies to individual blobs as well as the whole result set.
urn:virtuoso:restrictions:sql-result-rows - Limit the number of result rows.

Should no restriction apply to the authenticated person, then no limit will be enforced. Should multiple restrictions apply, then the least restrictive will apply.

Examples

Restriction Examples

Placeholders in the examples need to be replaced with actual values. {FINGERPRINT-URI} refers to a URI identifying a certificate by its fingerprint. Finderprint URIs have the following format: cert:XX:XX:XX:XX:XX:XX:XX.

Restrict The Request Rate

SPARQL

PREFIX oplres: <http://www.openlinksw.com/ontology/restrictions#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

WITH GRAPH <http://{HOST-CNAME}/acl/restrictions/groups/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm>

INSERT {
  <#RequestRate> a oplres:Restriction ;
    foaf:maker <{PERSON-WEBID}> ; 
    foaf:name "10 requests per second" ;
    oplres:hasMaxValue "10"^^xsd:decimal ;
    oplres:hasRestrictedResource <urn:virtuoso:restrictions:sql-request-rate> ;
    oplres:hasAgent <{FINGERPRINT-URI}> ;
    oplres:hasRealm oplacl:SqlRealm .
};

ACL Examples

Grant SPARQL Read Permissions to Anyone With a Valid Certificate

First we create the conditional group representing the validated certificates:

SPARQL

PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> 
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

WITH GRAPH <http://{HOST-CNAME}/acl/graph/groups/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm>

INSERT {
  <{GROUP-IRI}> a oplacl:ConditionalGroup ;
    foaf:name "Valid X.509 Certificates" ;
    foaf:maker <{PERSON-WEBID}> ; 
    oplacl:hasCondition [
      a oplacl:GroupCondition, oplacl:GenericCondition ;
      oplacl:hasCriteria oplacl:CertVerified ;
      oplacl:hasComparator oplacl:EqualTo ;
      oplacl:hasValue 1
    ] .
};

We then create the actual ACL rule referencing the group:

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://{HOST-CNAME}/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm>
insert {
  <{RULE-IRI}> a acl:Authorization ;
    foaf:maker <{PERSON-WEBID}> ; 
    oplacl:hasAccessMode oplacl:Read ;
    acl:accessTo <urn:virtuoso:access:sparql> ;
    acl:agent <{GROUP-IRI}> ;
    oplacl:hasScope oplacl:Query ;
    oplacl:hasRealm oplacl:SqlRealm .
};

Grant SPARQL Sponge Permission to One Certificate

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://{HOST-CNAME}/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm>
insert {
  <{RULE-IRI}> a acl:Authorization ;
    foaf:maker <{PERSON-WEBID}> ; 
    oplacl:hasAccessMode oplacl:Sponge ;
    acl:accessTo <urn:virtuoso:access:sparql> ;
    acl:agent <{FINGERPRINT-URI}> ;
    oplacl:hasScope oplacl:Query ;
    oplacl:hasRealm oplacl:SqlRealm .
};

Grant SPARQL Write Permissions For One Private Graph To One Certificate

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://{HOST-CNAME}/acl/graph/rules/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm>
insert {
  <{RULE-IRI}> a acl:Authorization ;
    foaf:maker <{PERSON-WEBID}> ; 
    oplacl:hasAccessMode oplacl:Write ;
    acl:accessTo <{GRAPH-IRI}> ;
    acl:agent <{FINGERPRINT-URI}> ;
    oplacl:hasScope oplacl:PrivateGraphs ;
    oplacl:hasRealm oplacl:SqlRealm .
};

Grant SPARQL Write Permissions Based on a SPARQL ASK Query

First we create the conditional group which contains a SPARQL ASK Query template for testing the existence of Group and Query conditions, in conjunction with a foaf:knows relation -- that has one WebID? (i.e., relation subject URI that denotes a foaf:Person entity e.g., http://kingsley.idehen.net/dataspace/person/kidehen#this ) as its subject and several other WebIDs? as its object.

This is an example of using social network oriented relations as the basis for SQL access privileges, granted via an Authorization.

SPARQL

PREFIX oplacl: <http://www.openlinksw.com/ontology/acl#> 
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

WITH GRAPH <http://{HOST-CNAME}/acl/graph/groups/http%3A%2F%2Fwww.openlinksw.com%2Fontology%2Facl%23SqlRealm>

INSERT {
  <{GROUP-IRI}> a oplacl:ConditionalGroup ;
    foaf:name "Known by {PERSON-NAME}" ;
    foaf:maker <{PERSON-WEBID}> ; 
    oplacl:hasCondition [
      a oplacl:GroupCondition, oplacl:QueryCondition ;
      oplacl:hasQuery """ask where {
          <{PERSON-WEBID}> foaf:knows ^{uri}^ .
        }"""
    ] .
};