SESSION-KEYRING
Section: Linux Programmer's Manual (7)
Updated: 2017-09-15
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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 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.)
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 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
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)
COLOPHON
This page is part of release 4.13 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
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- DESCRIPTION
-
- Special operations
-
- SEE ALSO
-
- COLOPHON
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