Writing SELinux Modules

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SELinux struggles to cast off its image as difficult to maintain and the cause of potential application problems. Yet in recent years, much has changed for the better, especially with regard to usability. For example, modules have replaced its monolithic set of rules. If you want to develop a new SELinux module, three files are typically necessary for this purpose.

Three Files for an SELinux Module

A type enforcement (.te) file stores the actual ruleset. To a large extent, it consists of m4 macros, or interfaces. For example, if you want to access a particular service’s resources, such as the logfiles, the service provides a corresponding interface for this purpose. If you want your own application to access these resources, you can draw this on the service’s interface without having to deal with the logfile details. For example, you do not need to know the logfile’s security label, because the interface abstracts access.

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