noble (7) user-session-keyring.7.gz

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 session 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 calling 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)