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'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.)
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 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> ...]
and:
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)