Chapter 10. PostgreSQL

PostgreSQL is an Object-Relational database management system (DBMS).[8]
In Red Hat Enterprise Linux 6, the postgresql-server package provides PostgreSQL. Run the rpm -q postgresql-server command to see if the postgresql-server package is installed. If it is not installed, run the following command as the root user to install it: 
~]# yum install postgresql-server

10.1. PostgreSQL and SELinux

When PostgreSQL is enabled, it runs confined by default. Confined processes run in their own domains, and are separated from other confined processes. If a confined process is compromised by an attacker, depending on SELinux policy configuration, an attacker's access to resources and the possible damage they can do is limited. The following example demonstrates the PostgreSQL processes running in their own domain. This example assumes the postgresql-server package is installed:
  1. Run the getenforce command to confirm SELinux is running in enforcing mode: 
    ~]$ getenforce
Enforcing
    The getenforce command returns Enforcing when SELinux is running in enforcing mode.
  2. Run the service postgresql start command as the root user to start postgresql: 
    ~]# service postgresql start
Starting postgresql service:                               [  OK  ]
  3. Run the ps -eZ | grep postgres command to view the postgresql processes: 
    ~]$ ps -eZ | grep postgres
unconfined_u:system_r:postgresql_t:s0 395 ?    00:00:00 postmaster
unconfined_u:system_r:postgresql_t:s0 397 ?    00:00:00 postmaster
unconfined_u:system_r:postgresql_t:s0 399 ?    00:00:00 postmaster
unconfined_u:system_r:postgresql_t:s0 400 ?    00:00:00 postmaster
unconfined_u:system_r:postgresql_t:s0 401 ?    00:00:00 postmaster
unconfined_u:system_r:postgresql_t:s0 402 ?    00:00:00 postmaster
    The SELinux context associated with the postgresql processes is unconfined_u:system_r:postgresql_t:s0. The second last part of the context, postgresql_t, is the type. A type defines a domain for processes and a type for files. In this case, the postgresql processes are running in the postgresql_t domain.

[8] Refer to the PostgreSQL project page for more information.