红帽全球峰会第 2 章 Changing SELinux states and modes
When enabled, SELinux can run in one of two modes: enforcing or permissive. By default, SELinux is enabled and runs in enforcing mode. Disabling SELinux or setting it to permissive mode prevents SELinux from protecting the system. Changing SELinux status by using the setenforce command is temporary and reverts after restart. To permanently change SELinux status, you must change SELinux configuration files or kernel parameters.
2.1. Permanent changes in SELinux states and modes
SELinux can be enabled or disabled. When enabled, SELinux has two modes: enforcing and permissive.
Use the getenforce or sestatus commands to check in which mode SELinux is running. The getenforce command returns Enforcing, Permissive, or Disabled.
The sestatus command returns the SELinux status and the SELinux policy being used:
$ sestatus
SELinux status: enabled
SELinuxfs mount: /sys/fs/selinux
SELinux root directory: /etc/selinux
Loaded policy name: targeted
Current mode: enforcing
Mode from config file: enforcing
Policy MLS status: enabled
Policy deny_unknown status: allowed
Memory protection checking: actual (secure)
Max kernel policy version: 31When systems run SELinux in permissive mode, users and processes might label various file-system objects incorrectly. File-system objects created while SELinux is disabled are not labeled at all. This behavior causes problems when changing to enforcing mode because SELinux relies on correct labels of file-system objects.
To prevent incorrectly labeled and unlabeled files from causing problems, SELinux automatically relabels file systems when changing from the disabled state to permissive or enforcing mode. Use the fixfiles -F onboot command as root to create the /.autorelabel file containing the -F option to ensure that files are relabeled upon next reboot.
Before rebooting the system for relabeling, make sure the system will boot in permissive mode, for example by using the enforcing=0 kernel option. This prevents the system from failing to boot in case the system contains unlabeled files required by systemd before launching the selinux-autorelabel service. For more information, see RHBZ#2021835.
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