The attached patch adds several interfaces to reference /selinux/status
according to sequential-lock logic.
selinux_status_open() open the kernel status page and mmap it with
read-only mode, or open netlink socket as a fallback in older kernels.
Then, we can obtain status information from the mmap'ed page using
selinux_status_updated(), selinux_status_getenfoce(),
selinux_status_policyload() or selinux_status_deny_unknown().
It enables to help to implement userspace avc with heavy access control
decision; that we cannot ignore the cost to communicate with kernel for
validation of userspace caches.
Signed-off-by: Steve Lawrence <slawrence@tresys.com>
