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session-keyring(7) [linux man page]

SESSION-KEYRING(7)					     Linux Programmer's Manual						SESSION-KEYRING(7)

NAME
session-keyring - session shared process keyring DESCRIPTION
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 con- figurations, 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's session keyring. From the keyctl(1) utility, '@s' can be used instead of a numeric key ID in much the same way. A process'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'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: keyctl_join_session_keyring(3) 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.) keyctl_session_to_parent(3) This operation allows the caller to make the parent process's session keyring to the same as its own. For this to succeed, the par- ent 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> ...] and: keyctl new_session SEE ALSO
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) Linux 2017-09-15 SESSION-KEYRING(7)

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PAM_KEYINIT(8)							 Linux-PAM Manual						    PAM_KEYINIT(8)

NAME
pam_keyinit - Kernel session keyring initialiser module SYNOPSIS
pam_keyinit.so [debug] [force] [revoke] DESCRIPTION
The pam_keyinit PAM module ensures that the invoking process has a session keyring other than the user default session keyring. The session component of the module checks to see if the process's session keyring is the user default, and, if it is, creates a new anonymous session keyring with which to replace it. If a new session keyring is created, it will install a link to the user common keyring in the session keyring so that keys common to the user will be automatically accessible through it. The session keyring of the invoking process will thenceforth be inherited by all its children unless they override it. This module is intended primarily for use by login processes. Be aware that after the session keyring has been replaced, the old session keyring and the keys it contains will no longer be accessible. This module should not, generally, be invoked by programs like su, since it is usually desirable for the key set to percolate through to the alternate context. The keys have their own permissions system to manage this. This module should be included as early as possible in a PAM configuration, so that other PAM modules can attach tokens to the keyring. The keyutils package is used to manipulate keys more directly. This can be obtained from: Keyutils[1] OPTIONS
debug Log debug information with syslog(3). force Causes the session keyring of the invoking process to be replaced unconditionally. revoke Causes the session keyring of the invoking process to be revoked when the invoking process exits if the session keyring was created for this process in the first place. MODULE TYPES PROVIDED
Only the session module type is provided. RETURN VALUES
PAM_SUCCESS This module will usually return this value PAM_AUTH_ERR Authentication failure. PAM_BUF_ERR Memory buffer error. PAM_IGNORE The return value should be ignored by PAM dispatch. PAM_SERVICE_ERR Cannot determine the user name. PAM_SESSION_ERR This module will return this value if its arguments are invalid or if a system error such as ENOMEM occurs. PAM_USER_UNKNOWN User not known. EXAMPLES
Add this line to your login entries to start each login session with its own session keyring: session required pam_keyinit.so This will prevent keys from one session leaking into another session for the same user. SEE ALSO
pam.conf(5), pam.d(5), pam(7) keyctl(1) AUTHOR
pam_keyinit was written by David Howells, <dhowells@redhat.com>. NOTES
1. Keyutils http://people.redhat.com/~dhowells/keyutils/ Linux-PAM Manual 06/04/2011 PAM_KEYINIT(8)
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