user-keyring(7) — Linux manual page

NAME | DESCRIPTION | SEE ALSO | COLOPHON

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

NAME         top

       user-keyring - per-user keyring

DESCRIPTION         top

       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-session-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) excepting that the keyring is destroyed
       when the UID record is destroyed when the last process pinning 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         top

       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         top

       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
       https://www.kernel.org/doc/man-pages/.

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

Pages that refer to this page: add_key(2)keyctl(2)request_key(2)keyrings(7)keyutils(7)persistent-keyring(7)process-keyring(7)session-keyring(7)thread-keyring(7)user-session-keyring(7)