What is the SIGKILL permissions policy?

Question

What is the SIGKILL permissions policy?

I assume I can't kill something of the kernel, or of some other user, while running on non-root, but I haven't found any document about this.

Answer 1

From http://linux.die.net/man/2/kill :

For a process to have permission to send a signal it must either be privileged (under Linux: have the CAP_KILL capability), or the real or effective user ID of the sending process must equal the real or saved set-user-ID of the target process. In the case of SIGCONT it suffices when the sending and receiving processes belong to the same session.