SELinux

Introduction

SELinux is a mandatory access control (MAC) system on Linux which adds a fine granular permission system for access to all resources on the system such as files, devices, networks and inter-process communication.

The most important questions are answered briefly in the FAQ of the SELinux Project. For more details on SELinux and how to actually use and administrate it on your systems have a look at Red Hat Enterprise Linux 7 - SELinux User’s and Administrator’s Guide. For a simplified (and funny) introduction download the SELinux Coloring Book.

Policy

Icinga Web 2 is providing its own SELinux policy for RPM-based systems running the targeted policy which confines Icinga Web 2 with support for all its modules.

The policy for Icinga Web 2 will also require the policy for Icinga 2 which provides access to its interfaces. It covers only the scenario running Icinga Web 2 in Apache HTTP Server with mod_php.

Use your distribution’s package manager to install the icingaweb2-selinux package.

General

When the SELinux policy package for Icinga Web 2 is installed, it creates its own type of apache content and labels its configuration icingaweb2_config_t to allow confining access to it.

Types

The configuration is labeled icingaweb2_config_t and other services can request access to it by using the interfaces icingaweb2_read_config and icingaweb2_manage_config. Files requiring read access are labeled icingaweb2_content_t. Files requiring write access are labeled icingaweb2_rw_content_t.

Booleans

SELinux is based on the least level of access required for a service to run. Using booleans you can grant more access in a defined way. The Icinga Web 2 policy package provides the following booleans.

httpd_can_manage_icingaweb2_config

Having this boolean enabled allows httpd to write to the configuration labeled icingaweb2_config_t. This is enabled by default. If not needed, you can disable it for more security. But this will disable all web based configuration of Icinga Web 2.

Optional Booleans

The Icinga Web 2 policy package does not enable booleans not required by default. In order to allow these things, you’ll need to enable them manually. (i.e. with the tool setsebool)

Ldap
If you want to allow httpd to connect to the ldap port, you must turn on the httpd_can_connect_ldap boolean. Disabled by default.

Bugreports

If you experience any problems while running SELinux in enforcing mode try to reproduce it in permissive mode. If the problem persists, it is not related to SELinux because in permissive mode SELinux will not deny anything.

When filing a bug report please add the following information additionally to the common ones: * Output of semodule -l | grep -e icinga2 -e icingaweb2 -e nagios -e apache * Output of semanage boolean -l | grep icinga * Output of ps -eZ | grep httpd * Output of audit2allow -li /var/log/audit/audit.log

If access to a file is blocked and you can tell which one, please provided the output of ls -lZ /path/to/file and the directory above.

If asked for full audit.log, add -w /etc/shadow -p w to /etc/audit/rules.d/audit.rules and restart the audit daemon. Reproduce the problem and add /var/log/audit/audit.log to the bug report. The added audit rule includes the path of files where access was denied.

If asked to provide full audit log with dontaudit rules disabled, execute semodule -DB before reproducing the problem. After that enable the rules again to prevent auditd spamming your logfile by executing semodule -B.