1USER-KEYRING(7)            Linux Programmer's Manual           USER-KEYRING(7)
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NAME

6       user-keyring - per-user keyring
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DESCRIPTION

9       The  user keyring is a keyring used to anchor keys on behalf of a user.
10       Each UID the kernel deals with has its own user keyring that is  shared
11       by  all processes with that UID.  The user keyring has a name (descrip‐
12       tion) of the form _uid.<UID> where <UID> is the user ID of  the  corre‐
13       sponding user.
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15       The  user  keyring  is associated with the record that the kernel main‐
16       tains for the UID.  It comes into existence upon the first  attempt  to
17       access  either  the  user  keyring, the user-session-keyring(7), or the
18       session-keyring(7).  The keyring remains pinned in existence so long as
19       there are processes running with that real UID or files opened by those
20       processes remain open.  (The keyring can also be pinned indefinitely by
21       linking it into another keyring.)
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23       Typically,  the  user  keyring is created by pam_keyinit(8) when a user
24       logs in.
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26       The user keyring is not searched by default  by  request_key(2).   When
27       pam_keyinit(8)  creates  a session keyring, it adds to it a link to the
28       user keyring so that the user keyring will be searched when the session
29       keyring is.
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31       A  special  serial number value, KEY_SPEC_USER_KEYRING, is defined that
32       can be used in  lieu  of  the  actual  serial  number  of  the  calling
33       process's user keyring.
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35       From  the  keyctl(1) utility, '@u' can be used instead of a numeric key
36       ID in much the same way.
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38       User keyrings are  independent  of  clone(2),  fork(2),  vfork(2),  ex‐
39       ecve(2),  and _exit(2) excepting that the keyring is destroyed when the
40       UID record is destroyed when the last process pinning it exits.
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42       If it is necessary for a key associated with a user to exist beyond the
43       UID  record  being  garbage collected—for example, for use by a cron(8)
44       script—then the persistent-keyring(7) should be used instead.
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46       If a user keyring does not exist when it is accessed, it will  be  cre‐
47       ated.
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SEE ALSO

50       keyctl(1), keyctl(3), keyrings(7), persistent-keyring(7),
51       process-keyring(7), session-keyring(7), thread-keyring(7),
52       user-session-keyring(7), pam_keyinit(8)
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COLOPHON

55       This page is part of release 5.10 of the Linux man-pages project.  A
56       description of the project, information about reporting bugs, and the
57       latest version of this page, can be found at
58       https://www.kernel.org/doc/man-pages/.
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62Linux                             2020-08-13                   USER-KEYRING(7)
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