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Virtual Private Database

Mohammad Amin Sabbaghian

Database Security – Virtual Private Database 3

What is VPD? Why use VPD? History of VPD Overview of Virtual Private Databases VPD components Benefits of using VPD Drawbacks of using VPD Summary

Agenda

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What is VPD?

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Acronym for Virtual Private Database

VPD enables you to enforce security, directly on tables, views or synonyms

Sometimes referred to as Oracle Row-Level Security (RLS) or Fine Grained Access Control (FGAC)

What is VPD?

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Allows to define which rows users may have access to

Dynamically returns a predicate against a target table

This activity is transparent to the user executing the SQL

What is VPD?

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Why use VPD?

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Protect confidential and secret information

Regulations such as HIPAA and SOX

You can have one database and control the delivery of the data to the right people

Why use VPD?

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History of VPD

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Oracle VPD was introduced in Oracle 8i Version 8.1.5 as a new solution to enforce granular access control of data at server level

In Oracle8i, the VPD provided the following key features:

- Fine grained Access Control - Application Context - Row Level Security - VPD support for table and view

History of VPD

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Oracle9i expanded the Virtual Private Database features as follows:

- Oracle Policy Manager - Partitioned fine-grained access control - Global application context - VPD support for synonyms

History of VPD

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Oracle 10g makes the following three major enhancements in Virtual Private Database:

Column-Level Privacy - It increases performance by limiting the number of queries that the database rewrites. Rewrites only occur when the statement references relevant columns. This feature also leads to more privacy.

Customization - With the introduction of four new types of policies, you can customize VPD to always enforce the same predicate with a static policy or you can have VPD predicates that change dynamically with a non-static policy.

Shared Policies - You can apply a single VPD policy to multiple objects, and therefore reduce administration costs.

11g provides integration for Enterprise manager for Row Level Security Policies.

History of VPD

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Overview of Virtual Private Databases

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A VPD deals with data access VPD controls data access at the row or column

level Oracle10/11g:

Fine-grained access control: associate security policies to database objects

Application Context: define and access application or session attributes

Combining these two features, VPD enables administrators to define and enforce row-level access control policies based on session attributes.

Overview of Virtual Private Databases

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Overview of Virtual Private Databases (continued)

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Overview of Virtual Private Databases (continued)

Step 0. Owner gives the policy and its function

Step 1 User sends SQL to the database server.

Step 2 The associated table triggers a pre-defined policy function.

Step 4. The server dynamically rewrites the submitted query by appending the returned predicate to the WHERE clause

Step 5. The modified SQL query is executed.

Step 3. The policy function returns a predicate, based on session attributes or database contents.

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BEGIN Dbms_rls.add_policy (object_schema=>'ret_schema', Object_name=>'retiree', Policy_name=>'retiree_policy', Function_schema=>'retiree', Policy_function=>'f_retiree_01', Statement_types=>'select', Sec_relevant_cols=>'ssn, sal'); END;

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Example

VPD Components

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Application Context

PL/SQL Function

Security Policies

VPD Components

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Holds environmental variables - Application name - Username

Gathers information using

Dbms_session.set_context

Application Context

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Functions are used to construct and return the Predicates that enforce the row-level security

The function must be called in the correct standard, to ensure that the policy can call the function correctly

Function returns a value

PL/SQL Function

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Benefits of using VPD

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Benefits of using VPD

Dynamic Security No need to maintain complex roles and grants

Multiple Security You can place more than one policy on each object, as

well as stack them on other base polices.

Simplicity

No backdoors Users can no longer bypass security polices embedded

in applications, as they are attached to the data Winter 2015

Drawbacks of using VPD

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Drawbacks of using VPD

Requires Oracle User ID VPD requires that an Oracle user Id be

defined to every person who connects to the database. This adds maintenance and overhead

Hard to audit It is hard to write an audit script that defines

the exact access for each user

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VPD Summary

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Summary

A virtual private database allows or prevents data access at the row or column level; implemented using VIEW database object

VPDs are also referred to as row-level security (RLS) or fine-grained access (FGA)

SQL Server does not support VPDs

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Summary (continued)

Oracle Application context: Allows setting of database application be

retrieved by database sessions SYS_CONTEXT function PL/SQL package DBMS_SESSION SET_CONTEXT procedure

Use Oracle-supplied package DBMS_RLS to add the VPD policy

Oracle data dictionary viewsWinter 2015

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VPD Summary

Security By attaching security policies to tables, views, or synonyms, fine-grained access control ensures that the same security is in force, no matter how a user accesses the data.

Simplicity Adding the security policy to the table, view, or synonym means that you make the addition only once, rather than repeatedly adding it to each of your table-, view-, or synonym-based applications.

Flexibility You can have one security policy for SELECT statements, another for INSERT statements, and still others for UPDATE and DELETE statements.

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Q&A

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http://en.wikipedia.org/wiki/Virtual_private_database

http://docs.oracle.com/cd/B28359_01/network.111/b28531/vpd.htm

http://www.utc.edu/center-information-security-assurance/course-listing/4670-lecture8-vpd.ppt

http://theoicllc.com/R12_GL/VPD_Sparks_Ver2.0.ppt

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Resources

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