I'm wondering about the security of UNIX signals.
SIGKILL will kill the process. So, what happens when a non root user's process sends a signal to a root user's process? Does the process still carry out the signal handler?
I follow the accepted answer (gollum's), and I type
man capabilites, and I find a lot of things about the Linux kernel. From
NAME capabilities - overview of Linux capabilities DESCRIPTION For the purpose of performing permission checks, traditional UNIX implementations distinguish two categories of processes: privileged processes (whose effective user ID is 0, referred to as superuser or root), and unprivileged processes (whose effective UID is nonzero). Privileged processes bypass all kernel permission checks, while unprivileged processes are subject to full permission checking based on the process's credentials (usually: effective UID, effective GID, and supplementary group list). Starting with kernel 2.2, Linux divides the privileges traditionally associated with superuser into distinct units, known as capabilities, which can be independently enabled and disabled. Capabilities are a per-thread attribute.