user-keyring(7) - man - phpMan

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



NAME
       user-keyring - per-user keyring

DESCRIPTION
       The  user  keyring is a keyring used to anchor keys on behalf of a user.  Each UID the kernel
       deals with has its own user keyring that is shared by all processes with that UID.  The  user
       keyring  has  a  name  (description) of the form _uid.<UID> where <UID> is the user ID of the
       corresponding user.

       The user 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 keyring, the user-ses‐‐
       sion-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.)

       Typically, the user keyring is created by pam_keyinit(8) when a user logs in.

       The user keyring is not searched by default by request_key(2).  When pam_keyinit(8) creates a
       session  keyring,  it  adds to it a link to the user keyring so that the user keyring will be
       searched when the session keyring is.

       A special serial number value, KEY_SPEC_USER_KEYRING, is defined that can be used in lieu  of
       the actual serial number of the calling process's user keyring.

       From  the  keyctl(1)  utility,  '@u' can be used instead of a numeric key ID in much the same
       way.

       User keyrings are independent of clone(2), fork(2), vfork(2), execve(2), and _exit(2) except‐
       ing that the keyring is destroyed when the UID record is destroyed when the last process pin‐
       ning it exits.

       If it is necessary for a key associated with a user to exist  beyond  the  UID  record  being
       garbage  collected—for  example,  for  use by a cron(8) script—then the persistent-keyring(7)
       should be used instead.

       If a user keyring does not exist when it is accessed, it will be created.

SEE ALSO
       keyctl(1), keyctl(3), keyrings(7), persistent-keyring(7), process-keyring(7),
       session-keyring(7), thread-keyring(7), user-session-keyring(7), pam_keyinit(8)

COLOPHON
       This page is part of release 5.10 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/.



Linux                                        2020-08-13                              USER-KEYRING(7)