USER-SESSION-KEYRING(7)      Kernel key management     USER-SESSION-KEYRING(7)

       user-session-keyring - Per-user default session keyring

       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.   This  keyring  is associated with the record that the kernel
       maintains for the UID and, once created, is retained as  long  as  that
       record persists.  It is shared amongst all processes of that UID.

       The user session keyring is created on demand when a thread requests it
       or when a thread asks for its session keyring and that  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() 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 calling process's user session
       keyring's actual serial number.

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

       User  session  keyrings  are  independent  of clone(), fork(), vfork(),
       execve() and exit() 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.

       It is strongly recommended that a session keyring  be  set  explicitly,
       for  example  by  pam_keyinit,  rather than relying on the user session
       keyring - particularly if a process is running as root.


Linux                             20 Feb 2014          USER-SESSION-KEYRING(7)
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