| EclipseLink Solutions Guide for EclipseLink Release 2.4 |
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A Virtual Private Database (VPD) uses security controls to restrict access to database objects based on various parameters.
For example, the Oracle Virtual Private Database supports security policies that control database access at the row and column level. Oracle VPD adds a dynamic WHERE clause to SQL statements issued against the table, view, or synonym to which the security policy was applied.
Oracle Virtual Private Database enforces security directly on the database tables, views, or synonyms. Because security policies are attached directly to these database objects, and the policies are automatically applied whenever a user accesses data, there is no way to bypass security.
When a user directly or indirectly accesses a table, view, or synonym that is protected with an Oracle Virtual Private Database policy, Oracle Database dynamically modifies the SQL statement of the user. This modification creates a WHERE condition (called a predicate) returned by a function implementing the security policy. Oracle Virtual Private Database modifies the statement dynamically, transparently to the user, using any condition that can be expressed in or returned by a function. Oracle Virtual Private Database policies can be applied to SELECT, INSERT, UPDATE, INDEX, and DELETE statements.
When using EclipseLink VPD multitanancy, the database handles the tenant filtering on all SELECT, INSERT, UPDATE, INDEX and DELETE queries.
To use EclipseLink VPD multi-tenancy, you must first configure VPD in the database and then specify multi-tenancy on the entity or mapped superclass, as shown in the following example, using @Multitenant and @TenantDiscriminatorColumn:
The following tasks provide instructions for using VPD multi-tenancy with Oracle Virtual Private Database:
To implement and use VPD multi-tenancy, you need:
EclipseLink 2.4 or later.
Download EclipseLink from http://www.eclipse.org/eclipselink/downloads/.
Any compliant Java Database Connectivity (JDBC) database that supports VDP, for example, Oracle Virtual Private Database.
For the certification matrix, see
In this example, an Oracle Virtual Private Database is configured with a policy and a stored procedure. The policy is a call to the database that tells the database to use a stored function to limit the results of a query. In this example, the function is called ident_func, and it is run whenever a SELECT, UPDATE or DELETE is performed on the SCOTT.TASK table. The policy is created as follows:
CALL DBMS_RLS.ADD_POLICY ('SCOTT', 'TASK', 'todo_list_policy', 'SCOTT', 'ident_func', 'select, update, delete'));
The function defined below is used by VPD to limit the data based on the identifier that is passed in to the connection. The function uses the USER_ID column in the table to limit the rows. The rows are limited, based on what is set in the client_identifier variable in the userenv context.
CREATE OR REPLACE FUNCTION ident_func (p_schema IN VARCHAR2 DEFAULT NULL, p_object IN VARCHAR2 DEFAULT NULL)
RETURN VARCHAR2
AS
BEGIN
RETURN 'USER_ID = sys_context(''userenv'', ''client_identifier'')';
END;
As described above, VPD is configured to use the USER_ID column to limit access to rows. Therefore, you must tell EclipseLink to auto-populate the USER_ID column on inserts. The following code uses EclipseLink multi-tenancy and specifies that the client identifier is passed in to the entity managers using a property called tenant.id. Because the filtering is done by VPD on the database, you must turn off caching on this entity to avoid leakage across users.
@Entity
@Multitenant(VPD)
@TenantDiscriminatorColumn(name = "USER_ID", contextProperty = "tenant.id")
@Cacheable(false)
public class Task implements Serializable {
...
...
When single-table and table-per-tenant multi-tenancy are enabled, a client identifier is auto appended to any generated SQL. However, when VPD is used to limit the access to data, the auto-appending of the identifier should be turned off.
Beginning with EclipseLink 2.4, disable criteria generation as follows:
@Multitenant(includeCriteria=false) @TenantDiscriminatorColumn(name = "USER_ID", contextProperty = "tenant.id")
In EclipseLink 2.3.1, you must run the following code from a SessionCustomizer:
session.getDescriptor(Task.class).getQueryManager().setIncludeTenantCriteria(false);
Add the following properties to persistence.xml.
Include the following to set and clear the VPD identifier:
<property name="eclipselink.session-event-listener" value="example.VPDSessionEventAdapter" />
Include the following to provide one connection per entity manager:
<property name="eclipselink.jdbc.exclusive-connection.mode" value="Always" />
Include the following to allow native queries to be runnable from EclipseLink. This is required for creating VPD artifacts:
<property name="eclipselink.jdbc.allow-native-sql-queries" value="true" /> </properties>
For example:
<properties> <property name="eclipselink.session-event-listener" value="example.VPDSessionEventAdapter" /> <property name="eclipselink.jdbc.exclusive-connection.mode" value="Always" /> <property name="eclipselink.jdbc.allow-native-sql-queries" value="true" /> ... </properties>
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