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

       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:

              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'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 5.11 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

Linux                              2021-03-22                 SESSION-KEYRING(7)