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Overview of Virtual Private Database

Manish PattaniSystem Performance & Architecture

(System Performance & Architecture

Rapid Knowledge Sharing)

Agenda

• What is VPD?• History of VPD • Why use VPD?• VPD components• Enforcement and Exceptions• Examples with Dynamic and Static Policies• Benefits of using VPD• Drawbacks of using VPD• Acknowledgements • Review

What is VPD?

What is VPD?

• 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)

• Allows to define which rows users may have access to

History of VPD

History of VPD

• 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

• Dynamically returns a predicate against a target table

• This activity is transparent to the user executing the SQL

History of VPD

• 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

• 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

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.

History of VPD

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

Why use VPD?

Why use VPD?

• 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

• VPD inclusive with Enterprise Edition – no fees

VPD Components

VPD Components

• Application Context

• PL/SQL Function

• Security Policies

Application Context

• Holds environmental variables

- Application name

- Username

• Gathers information using Dbms_session.set_context

PL/SQL Function

• 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

Security Policies

• Static

• Non-Static

• Dynamic (Default)      

Security Policies (Static)

                              

STATIC 

The policy function is executed once, and the resulting string (the predicate) is stored in the Shared Global Area (SGA).

Security Policies (Non-Static)

                              

• SHARED_STATIC

Allows the predicate to be cached across multiple objects that use the same policy function.

Security Policies (Non-Static)

• CONTEXT_SENSITIVE 

The server always executes the policy function on statement parsing. The server will only execute the policy function on statement execution if it detects context changes. This makes it ideal for connection pooling solutions that share a database schema and use application contexts to actually perform the user identity switching.

Security Policies (Non-Static)

                              

• SHARED_CONTEXT_SENSITIVE 

The same as CONTEXT_SENSITIVE except that the policy can be shared across multiple objects that use the same policy function.

Security Policies (Dynamic)

                              

• DYNAMIC

The default, which makes no assumptions about caching. This policy will be invoked every time the SQL statement is parsed or executed

Enforcement and Exceptions

Enforcement and Exceptions

• VPD is not enforced during DIRECT path export

• VPD policies cannot be applied to objects in the SYS schema

• Any users with EXEMPT ACCESS POLICY directly or indirectly thru a role, are exempt from VPD enforcements

• Administrators can enforce VPD policies on index maintenance operations by specifying INDEX with the statement_types parameter

Examples of Dynamic and Static Policies

Example of Dynamic Policy

SQL> create user vpd Create user2 identified by vpd3 default tablespace users4 temporary tablespace temp5 /User created.

SQL> create user pattani Create user2 identified by pattani3 default tablespace users4 temporary tablespace temp5 /User created.

Example of Dynamic Policy

SQL> grant connect,resource to vpd,pattani;

Grant succeeded.

SQL> grant execute on dbms_rls to vpd;

Grant succeeded.

SQL> grant select on scott.emp to pattani,vpd;

Grant succeeded.

Example of Dynamic Policy

SQL> connect vpd/vpdConnected.

SQL> create table vpd_ply as select ename,deptno from scott.emp;

Table created.

SQL> select * from vpd_ply;ENAME DEPTNO---------- ----------SMITH 20ALLEN 30.

Example of Dynamic Policy

SQL> insert into vpd_ply values('PATTANI',30);1 row created.

SQL> commit;Commit complete.

SQL> create or replace function fun_vpd_emp 2 (3 p_schema in varchar2, 4 p_table in varchar2 5 )6 return varchar27 as8 l_retstr varchar2(2000);

Example of Dynamic Policy

9 begin

10 if (p_schema = user) then

11 l_retstr := null;

12 else

13 for user_rec in

14 (

15 select deptno

16 from vpd_ply

17 where ename = user

18 ) loop

19 l_retstr := l_retstr||','||user_rec.deptno;

20 end loop;

Example of Dynamic Policy

21 l_retstr := ltrim(l_retstr,',');22 if (l_retstr is null) then23 l_retstr := '0=1';24 else25 l_retstr := 'DEPTNO IN ('||l_retstr||')';26 end if;27 end if;28 return l_retstr;29 end;30 /Function created.SQL> grant execute on fun_vpd_emp to public;Grant succeeded.

Example of Dynamic Policy

SQL> connect vpd/vpd

SQL> begin

2 dbms_rls.add_policy (

3 object_schema => 'SCOTT',

4 object_name => 'EMP',

5 policy_name => 'EMP_DEPTNO_PLY_1',

6 function_schema => 'VPD',

7 policy_function => 'FUN_VPD_EMP',

8 statement_types => 'SELECT'

9 );

10 end;

11/

Example of Dynamic Policy

SQL> begin

2 dbms_rls.add_policy (

3 object_schema => 'SCOTT',

4 object_name => 'EMP',

5 policy_name => 'EMP_DEPTNO_PLY_2',

6 function_schema => 'VPD',

7 policy_function => 'FUN_VPD_EMP',

8 statement_types => 'INSERT, UPDATE, DELETE',

9 update_check => TRUE

10 );

11 end;

12 /

Example of Dynamic Policy

Login as Scott userSQL> select count(*) from emp;COUNT(*)----------14Login as pattani userSQL> select count(*) from scott.emp;COUNT(*)----------6SQL> delete from scott.emp where deptno<>30;0 rows deleted.SQL> update scott.emp set sal=sal+100;6 rows updated.

Example of Dynamic Policy

SQL> insert into scott.emp(empno,ename,deptno) values

(9999,'VPD',10);

insert into scott.emp(empno,ename,deptno) values(9999,'VPD',10)

*

ERROR at line 1:

ORA-28115: policy with check option violation

Example with Static Policy

As Scott user

CREATE OR REPLACE function pol_func (objowner in varchar2, objname in varchar2) returnvarchar2 as deptno number;beginreturn 'empno = 7934';end;/

 CREATE OR REPLACE FUNCTION myUpper (var in VARCHAR2)RETURN VARCHAR2 DETERMINISTIC ASBEGINRETURN UPPER(var);END;/

Example with Static Policy

• As System or sys user

exec dbms_rls.add_policy (object_schema => 'SCOTT',object_name => 'EMP',policy_name => 'pol1',function_schema => 'SCOTT',policy_function => 'pol_func',statement_types => 'select, index',update_check => true);

As scott user

when trying to create an index when index is also part of statement_type following error is raised.

SQL> CREATE INDEX emp_i ON scott.emp (SUBSTR(myupper(ename),1,20)) ;CREATE INDEX emp_i ON scott.emp (SUBSTR(myupper(ename),1,20))                            *ERROR at line 1:ORA-28133: full table access is restricted by fine-grained security

Benefits of using VPD

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.

• No backdoors Users can no longer bypass security polices embedded in

applications, as they are attached to the data

Drawbacks of using VPD

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

VPD Summary

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.

Review

Review

• VPD Evolution

• Various VPD Components

• Pros and Cons of VPD

Acknowledgements

Acknowledgements

• Avadhani Yanamandra

• Peter Shi

• Sameer Mehta

• Winston Shirley

References

• Oracle® Database Security Guide Documentation

• VPD White Papers

• Metalink article 250795.1 - 10G: Policy Enforced Only When the Relevant Column is Queried in Any Way

• Metalink article 281829.1 - Evolution of Fine Grain Access Control FGAC Feature From 8i to 10g and it has lots of links to FGA

• http://asktom.oracle.com

• http://www.petefinnigan.com/orasec.htm (Oracle security papers)

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