For most applications, the SELinux subsystem in the Linux kernel is capable of enforcing security controls without further interaction with other applications and components. However, there are actions that cannot be handled by the SELinux subsystem autonomously. Some applications execute commands for specific users, but the target domain cannot be deduced from the path of the application that is itself being executed, making type transitions based on the label impossible.
One solution for this problem is to make the application SELinux-aware, having the application interrogate the SELinux subsystem as to what should be the context of the newly executed application. Once the context is obtained, the application can then instruct the SELinux subsystem that this context can be assigned to the process that will be launched next.
Of course, it isn't only about deciding what context a process should be in. Applications can also check the SELinux policy and act on the policy themselves...
