/etc/selinux/config file is the main SELinux configuration file. It controls whether SELinux is enabled or disabled and which SELinux mode and SELinux policy is used:
# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
# enforcing - SELinux security policy is enforced.
# permissive - SELinux prints warnings instead of enforcing.
# disabled - No SELinux policy is loaded.
# SELINUXTYPE= can take one of these two values:
# targeted - Targeted processes are protected,
# mls - Multi Level Security protection.
option sets whether SELinux is disabled or enabled and in which mode - enforcing or permissive - it is running:
SELINUX=enforcing, SELinux policy is enforced, and SELinux denies access based on SELinux policy rules. Denial messages are logged.
SELINUX=permissive, SELinux policy is not enforced. SELinux does not deny access, but denials are logged for actions that would have been denied if running SELinux in enforcing mode.
SELINUX=disabled, SELinux is disabled (the SELinux module is not registered with the Linux kernel), and only DAC rules are used.
option sets the SELinux policy to use. Targeted policy is the default policy. Only change this option if you want to use the MLS policy. For information on how to enable the MLS policy, refer to Section 5.11.2, “Enabling MLS in SELinux”