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KEYCTL_SESSION_TO_PARENT

set the parent process's session keyring

Standard C library (libc, -lc)

#include <linux/keyctl.h>  /* Definition of KEY* constants */
#include <sys/syscall.h>   /* Definition of SYS_* constants */
#include <unistd.h>
long syscall(SYS_keyctl, KEYCTL_SESSION_TO_PARENT);

Replace the session keyring to which the parent of the calling process subscribes with the session keyring of the calling process.

The keyring will be replaced in the parent process at the point where the parent next transitions from kernel space to user space.

The keyring must exist and must grant the caller link permission. The parent process must be single-threaded and have the same effective ownership as this process and must not be set-user-ID or set-group-ID. The UID of the parent process's existing session keyring (f it has one), as well as the UID of the caller's session keyring much match the caller's effective UID.

The fact that it is the parent process that is affected by this operation allows a program such as the shell to start a child process that uses this operation to change the shell's session keyring. (This is what the keyctl(1) new_session command does.)

On success, 0 is returned.

On error, -1 is returned, and errno is set to indicate the error.

All of the UIDs (GIDs) of the parent process do not match the effective UID (GID) of the calling process.
The UID of the parent's existing session keyring or the UID of the caller's session keyring did not match the effective UID of the caller.
The parent process is not single-threaded.
The parent process is init(1) or a kernel thread.

A wrapper is provided in the libkeyutils library: keyctl_session_to_parent(3).

Linux.

Linux 2.6.32.

keyctl(2), keyctl_session_to_parent(3)