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

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

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Linux                            2017-03-13                  USER-KEYRING(7)