Concepts of Database Security - Multilevel Security for Relational Databases - page 13

In RBAC, database administrators can manage access at a level of
abstraction that is identical to the way that organizations perform their
business. This is achieved by organizing users' tasks through the imple-
mentation of roles, role hierarchies, relationships, and constraints.
In role-based access control, roles can have overlapping duties and
privileges, so users assigned many roles may need to do common tasks.
Some general tasks may be done by all users. In this situation, there is
no need to repeat these common tasks for each role created. Role hier-
archies can be performed to present the real structure of an enterprise.
RBAC has two types of role hierarchies:
• General hierarchical RBAC is based on the concept of mul-
tiple inheritances that present the ability to obtain permission
inheritance from more than one role and to inherit user mem-
bership from more than one role.
• Limited hierarchical RBAC is limited to a single descendant.
Limited role hierarchies do not support multiple inheritances.
1.4 Work Objectives
In the digital world nowadays, database security has become increas-
ingly important since the database is the primary repository of infor-
mation for organizations and governments. More and more research
has been developed in database security to protect the data from pos-
sible unauthorized instructions. Most of the security models available
for databases today protect them from outside and unauthorized users.
Multilevel security for relational databases provides internal secu-
rity in relationship with the user's access to the relational database.
Relational database multilevel security systems have been proposed
to address the increased security needs of relational database systems.
Although multilevel concepts were originally developed to support
confidentiality in military systems, there are now many commercial
systems that use multilevel security policies.
Although many models have been developed to support multilevel
security in the relational database, there are many problems in imple-
menting multilevel security policies. These problems included complexity
in designing multilevel security for the relational database and increas-
ing the database size according to the classification level columns added
to the original database to support multilevel security in the database.