In-kernel key management utilities
The keyutils package is a library and a set of utilities for accessing the kernel keyrings facility.
A header file is supplied to provide the definitions and declarations required to access the library:
To link with the library, the following:
should be specified to the linker.
Three system calls are provided:
Supply a new key to the kernel.
Find an existing key for use, or, optionally, create one if one does not exist.
Control a key in various ways. The library provides a variety of wrappers around this system call and those should be used rather than calling it directly.
The keyctl() wrappers are listed on the keyctl(3) manual page.
A program is provided to interact with the kernel facility by a number of subcommands, e.g.:
keyctl add user foo bar @s
See the keyctl(1) manual page for information on that.
The kernel has the ability to upcall to userspace to fabricate new keys. This can be triggered by request_key(), but userspace is better off using add_key() instead if it possibly can.
The upcalling mechanism is usually routed via the:
program. What this does with any particular key is configurable in: