Access Control & OS: SOLARIS
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SOLARIS. Sun’s Solaris operating system is in essence a
UNIX-based OS, especially since a large part of early UNIX-based OSs
were developed by Sun Systems. The file hierarchy is the same as in UNIX
systems, with the exception that user accounts created are given a home
directory with the path as /export/home/username. All users are given
UIDs when their accounts are created. Also, users can be grouped in
different groups to assign similar permissions to each. The new features
in Solaris systems include use of user templates, projects and the
prominent RBAC access control. We shall discuss these in more detail.
User templates can be created in order to set up a template with
certain fixed attributes for users. Then users that have similar
properties like students, engineers etc can be created using user
templates. Users can be assigned to certain projects which associates
them with a certain workload component. This is very useful when it
comes to resource allocation.
Role-based Access control was introduced in Solaris systems from
Solaris 8 onwards. It was introduced with the intention of
administrative purpose, which is why the roles are called administrative
roles. The idea although similar to the superuser or root, was developed
to overcome the shortcomings of having these accounts. The problem with
having superuser or root accounts was that anyone who would be able to
hijack these accounts, would be all-powerful in the system. But with the
use of RBAC in the Solaris system, the Principle of Least Privilege
could be enforced. By this, users could be given some administrative
rights, but only to the extent that was required. Figure 4: Role-based
feature
Figure 4
In the Solaris system, rights are grouped together in to what are called
right profiles. These right profiles are then assigned to roles, which
users can assume in order to carry out some administrative operations.
No roles are created by default, but 3 recommended roles are:
- Primary Administrator – All powerful and
similar to the root or superuser
- System Administrator – Administrative
privileges without security rights
- Junior Administrator – Administration over some
operations like backup, printing etc.
It is to be noted, that roles are totally a function of the
organizations needs. The RBAC model introduces some interesting concepts
in Solaris. An authorization is a permission to perform a certain class
of actions. A privilege is a discrete right that can be assigned to a
user, system or object. A security attribute is an attribute that allows
a certain process to successfully carry out an operation. Privileged
applications can use security attributes to override system controls and
perform operations, like setuid and setgid in UNIX systems. A rights
profile is a collection of administrative capabilities, and can consist
of authorizations, security attributes and even other rights profiles.
Finally a role is defined as a special identity for running privileged
applications. Roles run privileged applications from a separate shell
called profile shell which is a different shell that can recognize
security attributes. All of these entities work together as shown in
Figure 4.
File Access in Solaris can be controlled through regular UNIX commands
as mentioned in the previous section. But a more granular way of
controlling access to files is with the help of ACLs. Unlike in UNIX,
where all users, groups and others are assigned permissions to a given
file, ACLs allow control of access by specific users or groups. This
allows finer access control. Access to devices is controlled with the
help of device policies and device allocation, which are enforced at the
kernel and user allocation time respectfully. In the following lab
exercises, some of the tasks are to be performed on the Sun Management
Console while the rest are to be performed from command line, through a
terminal window. The Sun Management Console (SMC) can be executed at a
terminal window as
$ /usr/sbin/smc &
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