Discretionary access controls

Discretionary access controls includes about Discretionary Access Controls (DAC, Access Matrix Model), DAC in Relational Database (DAC, Privileges, The System R Access Control, Content–Based Access Control, Demo).

 Discretionary Access Controls

 DAC

 Access Matrix Model

 DAC

 Privileges

 The System R Access Control

 Content–Based Access Control

 Demo

 Q & A

Discretionary Access Controls

 DAC is based on the identity of the user

requesting access and on a set of rules, call

authorizatons , explicitly stating which user can

perform which action on which resource

Discretionary Access Controls

 DAC

Bob

Document1

Access Matrix Model

 Access Matrix Model: The first discretionary

access control model proposed

Access Matrix Model

 Access Matrix Model: The first discretionary

access control model proposed

 Triple (S,O,A)

 S: subject; O: objects; A: actions; A[s,o] : contains the list of actions that subject s can execute over object o

Sn A[sn,o1] A[sn,oi] A[sn,om]

Access Matrix Model

 Model implementation:

 S {(O,A)}: capability list

 O{(S,A)}: ACL (access control list)

Access Matrix Model

Access Matrix Model

Access matrix implementation

DAC in Relational Database

Discretionary Access Control (DAC)

 The typical method of enforcing discretionary access control in a database system is based

on the granting and revoking privileges

 User can protect what they own

 Owner may grant access to other

 Owner can define the type of access

(read/write/execute/…) given to others

 Object level

Privileges

 The create schema or create table privilege

 The create view privilege

 The alter privilege

 The drop privilege

 The modify privilege

 The select privilege

 Object level: applies to relation or view

Table Employee Table Department

View 1 View 2

Alice  does not want  Bob to access the  Employee relation ?

Revoke select ON Emp, Dept From Jack 

Inherent weakness of DAC

object which can be read by a subject to be

written to any other object

 Suppose our users are trusted not to do this

deliberately It is still possible for Trojan Horses

Trojan Horse Example

Trojan Horse Example

The System R Access Control Model

 The main protection objects are tables and

views

Content–Based Access Control

Content–Based Access Control

 Essentially, content-based access control

requires that access control decisions be based

on data contents

 A content-based access control policy: a

manager can only access the employees that

work in his/her division

Content–Based Access Control

Content–Based Access Control

Create view Emp_Jack

as select ename, salary from Emp

With read only

Content–Based Access Control

Jack

GRANT insert, delete ON Emp, Dept

TO Red

Create view Emp_Jack

as select * from Emp where name=‘Jack‘

With read only

Content–Based Access Control

 Too many views to create

 Complicated policy logic can be difficult to express and

to update

 Oracle

 Discretionary Access Controls

 DAC

 Access Matrix Model

 DAC

 Privileges

 The System R Access Control

 Content–Based Access Control

 Demo

[1] M Gertz, S Jajodia: “Handbook of Database Security: Applications and

Trends”, Springer Verlag, 2009

[2] E Bertino, G Ghinita, A Kamra: "Access Control for Databases: Concepts

and Systems", Now Publishers, 3(1-2):1-148, 2011

[3] Truong Quynh Chi, DAC.

[4] Oracle Corporation : “Leveraging Oracle Database Security with J2EE Container Managed Persistence ” (white paper).

[5] Oracle® Database Security Guide 11g Release 1 (11.1)

http://docs.oracle.com/cd/B28359_01/network.111/b28531/vpd.htm#DBSEG0 07

12/11/15 www.cse.hcmut.edu.vn 32