Security-Enhanced Linux (SELinux) is a mandatory access control (MAC) system that implements access rights by applying a security label referred to as an SELinux context to each system object. SELinux policy modules use SELinux contexts to define rules for how processes, files, ports, and other system objects interact with each other. Interaction between system objects is only permitted if a policy rule allows it.

An SELinux context (the label applied to a system object) has the following fields: user, role, type, and security level. Type information rather than the entire SELinux context is used most commonly to define rules for how processes interact with other system objects. MySQL SELinux policy modules, for example, define policy rules using type information.

You can view SELinux contexts using operating system commands such as ls and ps with the -Z option. Assuming that SELinux is enabled and a MySQL Server is running, the following commands show the SELinux context for the mysqld process and MySQL data directory:

mysqld process:

$> ps -eZ | grep mysqld
system_u:system_r:mysqld_t:s0    5924 ?        00:00:03 mysqld

MySQL data directory:

$> cd /var/lib
$> ls -Z | grep mysql
system_u:object_r:mysqld_db_t:s0 mysql

where:

For more information about interpreting SELinux contexts, refer to your distribution's SELinux documentation.