int security_setenforce(int value);
security_setenforce() sets SELinux to enforcing mode if the value 1 is passed in, and sets it to permissive mode if 0 is passed in. On success 0 is returned, on error -1 is returned.
security_deny_unknown() returns 0 if SELinux treats policy queries on undefined object classes or permissions as being allowed, 1 if such queries are denied, and -1 on error.
security_get_checkreqprot() can be used to determine whether SELinux is configured to check the protection requested by the application or the actual protection that will be applied by the kernel (including the effects of READ_IMPLIES_EXEC) on mmap and mprotect calls. It returns 0 if SELinux checks the actual protection, 1 if it checks the requested protection, and -1 on error.