Section (7) session-keyring

Linux manual pages Section 7  


session-keyring — session shared process keyring


The session keyring is a keyring used to anchor keys on behalf of a process. It is typically created by pam_keyinit(8) when a user logs in and a link will be added that refers to the user-keyring(7). Optionally, PAM may revoke the session keyring on logout. (In typical configurations, PAM does do this revocation.) The session keyring has the name (description) _ses.

A special serial number value, KEY_SPEC_SESSION_KEYRING, is defined that can be used in lieu of the actual serial number of the calling process_zsingle_quotesz_s session keyring.

From the keyctl(1) utility, _zsingle_quotesz_@s_zsingle_quotesz_ can be used instead of a numeric key ID in much the same way.

A process_zsingle_quotesz_s session keyring is inherited across clone(2), fork(2), and vfork(2). The session keyring is preserved across execve(2), even when the executable is set-user-ID or set-group-ID or has capabilities. The session keyring is destroyed when the last process that refers to it exits.

If a process doesn_zsingle_quotesz_t have a session keyring when it is accessed, then, under certain circumstances, the user-session-keyring(7) will be attached as the session keyring and under others a new session keyring will be created. (See user-session-keyring(7) for further details.)

Special operations

The keyutils library provides the following special operations for manipulating session keyrings:


This operation allows the caller to change the session keyring that it subscribes to. The caller can join an existing keyring with a specified name (description), create a new keyring with a given name, or ask the kernel to create a new anonymous session keyring with the name _ses. (This function is an interface to the keyctl(2) KEYCTL_JOIN_SESSION_KEYRING operation.)


This operation allows the caller to make the parent process_zsingle_quotesz_s session keyring to the same as its own. For this to succeed, the parent process must have identical security attributes and must be single threaded. (This function is an interface to the keyctl(2) KEYCTL_SESSION_TO_PARENT operation.)

These operations are also exposed through the keyctl(1) utility as:

keyctl session
keyctl session - [<prog> <arg1> <arg2> ...]
keyctl session <name> [<prog> <arg1> <arg2> ...]


keyctl new_session


keyctl(1), keyctl(3), keyctl_join_session_keyring(3), keyctl_session_to_parent(3), keyrings(7), persistent-keyring(7), process-keyring(7), thread-keyring(7), user-keyring(7), user-session-keyring(7), pam_keyinit(8)


This page is part of release 5.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at−pages/.

Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
Written by David Howells (

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version
2 of the License, or (at your option) any later version.