21.2. Files Related to SELinux

21.2.2.1. The /etc/sysconfig/selinux Configuration File

There are two ways to configure SELinux under Red Hat Enterprise Linux: using the Security Level Configuration Tool (system-config-securitylevel), or manually editing the configuration file (/etc/sysconfig/selinux).

The /etc/sysconfig/selinux file is the primary configuration file for enabling or disabling SELinux, as well as setting which policy to enforce on the system and how to enforce it.

	Note
	The /etc/sysconfig/selinux contains a symbolic link to the actual configuration file, /etc/selinux/config.

The following explains the full subset of options available for configuration:

• SELINUX=<enforcing|permissive|disabled> — Defines the top-level state of SELinux on a system.

  • enforcing — The SELinux security policy is enforced.

  • permissive — The SELinux system prints warnings but does not enforce policy. This is useful for debugging and troubleshooting purposes. In permissive mode, more denials will be logged, as subjects will be able to continue with actions otherwise denied in enforcing mode. For example, traversing a directory tree will produce multiple avc: denied messages for every directory level read, where a kernel in enforcing mode would have stopped the initial traversal and kept further denial messages from occurring.

  • disabled — SELinux is fully disabled. SELinux hooks are disengaged from the kernel and the pseudo-file system is unregistered.

    	Tip
    	Actions made while SELinux is disabled may cause the file system to no longer have the proper security context as defined by the policy. Running fixfiles relabel prior to enabling SELinux will relabel the file system so that SELinux works properly when enabled. For more information, refer to the fixfiles(8) manpage.

  	Note
  	Additional white space at the end of a configuration line or as extra lines at the end of the file may cause unexpected behavior. To be safe, remove unnecessary white spaces.

• SELINUXTYPE=<targeted|strict> — Specifies which policy is currently being enforced by SELinux.

  • targeted — Only targeted network daemons are protected.

    	Important
    	The following daemons are protected in the default targeted policy: dhcpd, httpd (apache.te), named, nscd, ntpd, portmap, snmpd, squid, and syslogd. The rest of the system runs in the unconfined_t domain. The policy files for these daemons can be found in /etc/selinux/targeted/src/policy/domains/program and are subject to change, as newer versions of Red Hat Enterprise Linux are released.

    Policy enforcement for these daemons can be turned on or off, using Boolean values controlled by Security Level Configuration Tool (system-config-securitylevel). Switching a Boolean value for a targeted daemon disables the policy transition for the daemon, which prevents, for example, init from transitioning dhcpd from the unconfined_t domain to the domain specified in dhcpd.te. The domain unconfined_t allows subjects and objects with that security context to run under standard Linux security.

  • strict — Full SELinux protection, for all daemons. Security contexts are defined for all subjects and objects, and every single action is processed by the policy enforcement server.

21.2.2.2. The /etc/selinux/ Directory

The /etc/selinux/ directory is the primary location for all policy files as well as the main configuration file.

The following example shows sample contents of the /etc/selinux/ directory:

-rw-r--r--  1 root root  448 Sep 22 17:34 config
drwxr-xr-x  5 root root 4096 Sep 22 17:27 strict
drwxr-xr-x  5 root root 4096 Sep 22 17:28 targeted

The two subdirectories, strict/ and targeted/, are the specific directories where the policy files of the same name (i.e., strict and targeted) are contained.

For more information on SELinux policy and policy configuration, refer to the rhel-pwg-selinux.