Getting ring 0 mode in C++ (Windows)

Question

How I can get ring 0 operating mode for my process in Windows 7(or Vista)?

Answer 1

Allowing arbitrary code to run in ring 0 violates basic OS security principles.

Only the OS kernel and device drivers run in ring 0. If you want to write ring 0 code, write a Windows device driver. This may be helpful.

Certain security holes may allow your code to run in ring 0 also, but this isn't portable because the hole might be fixed in a patch :P

Answer 2

You cannot set kernel mode from a user mode process. That's how security works.

Answer 3

Technically speaking, all processes have some threads spending some of their time in Kernel-Mode (ring 0). Whenever a user-mode process makes a syscall into the OS, there is a transition where the thread gets into ring 0 via a 'gate'. Whenever a process needs to talk to a device, allocate more process-wide memory, or spawn new threads, a syscall is used to ask the OS to provide this service.

Therefore, if you want to have a process run some code in ring 0, you'll need to write a driver and then communicate with this driver thru some syscalls. The most common syscall for this is called ioctl (stands for I/O Control).

Another thing to look at on the Windows platform is the UMDF (User-Mode Driver Framework). This allows you to write, debug, and test a driver in user-mode (running in ring 3) but it is still accessible to other drivers or other processes in the system.