user-session-keyring(7) [linux man page]

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

NAME

       user-session-keyring - per-user default session keyring

DESCRIPTION

       The  user  session  keyring  is a keyring used to anchor keys on behalf of a user.  Each UID the kernel deals with has its own user session
       keyring that is shared by all processes with that UID.  The user session keyring has a name (description) of the form _uid_ses.<UID>  where
       <UID> is the user ID of the corresponding user.

       The  user  session  keyring  is	associated  with the record that the kernel maintains for the UID.  It comes into existence upon the first
       attempt to access either the user session keyring, the user-keyring(7), or the session-keyring(7).  The keyring remains pinned in existence
       so  long as there are processes running with that real UID or files opened by those processes remain open.  (The keyring can also be pinned
       indefinitely by linking it into another keyring.)

       The user session keyring is created on demand when a thread requests it or when a thread asks for its session-keyring(7) and  that  keyring
       doesn't	exist.	In the latter case, a user session keyring will be created and, if the session keyring wasn't to be created, the user ses-
       sion keyring will be set as the process's actual session keyring.

       The user session keyring is searched by request_key(2) if the actual session keyring does not exist and is ignored otherwise.

       A special serial number value, KEY_SPEC_USER_SESSION_KEYRING, is defined that can be used in lieu of the actual serial number of the  call-
       ing process's user session keyring.

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

       User  session keyrings are independent of clone(2), fork(2), vfork(2), execve(2), and _exit(2) excepting that the keyring is destroyed when
       the UID record is destroyed when the last process pinning it exits.

       If a user session keyring does not exist when it is accessed, it will be created.

       Rather than relying on the user session keyring, it is strongly recommended--especially if the process is running as root--that a  session-
       keyring(7) be set explicitly, for example by pam_keyinit(8).

NOTES

       The user session keyring was added to support situations where a process doesn't have a session keyring, perhaps because it was created via
       a pathway that didn't involve PAM (e.g., perhaps it was a daemon started by inetd(8)).  In such a scenario, the user session  keyring  acts
       as a substitute for the session-keyring(7).

SEE ALSO

       keyctl(1), keyctl(3), keyrings(7), persistent-keyring(7), process-keyring(7), session-keyring(7), thread-keyring(7), user-keyring(7)

Linux								    2017-03-13						   USER-SESSION-KEYRING(7)

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(8)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						    09/19/2013							    PAM_KEYINIT(8)