166 lines
5.0 KiB
HTML
166 lines
5.0 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of USER-SESSION-KEYRING</TITLE>
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</HEAD><BODY>
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<H1>USER-SESSION-KEYRING</H1>
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Section: Linux Programmer's Manual (7)<BR>Updated: 2017-03-13<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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user-session-keyring - per-user default session keyring
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<A NAME="lbAC"> </A>
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<H2>DESCRIPTION</H2>
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The user session keyring is a keyring used to anchor keys on behalf of a user.
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Each UID the kernel deals with has its own user session keyring that
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is shared by all processes with that UID.
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The user session keyring has a name (description) of the form
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<I>_uid_ses.<UID></I>
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where
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<I><UID></I>
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is the user ID of the corresponding user.
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<P>
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The user session keyring is associated with the record that
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the kernel maintains for the UID.
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It comes into existence upon the first attempt to access either the
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user session keyring, the
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<B><A HREF="/cgi-bin/man/man2html?7+user-keyring">user-keyring</A></B>(7),
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or the
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<B><A HREF="/cgi-bin/man/man2html?7+session-keyring">session-keyring</A></B>(7).
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The keyring remains pinned in existence so long as there are processes
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running with that real UID or files opened by those processes remain open.
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(The keyring can also be pinned indefinitely by linking it
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into another keyring.)
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<P>
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The user session keyring is created on demand when a thread requests it
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or when a thread asks for its
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<B><A HREF="/cgi-bin/man/man2html?7+session-keyring">session-keyring</A></B>(7)
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and that keyring doesn't exist.
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In the latter case, a user session keyring will be created and,
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if the session keyring wasn't to be created,
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the user session keyring will be set as the process's actual session keyring.
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<P>
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The user session keyring is searched by
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<B><A HREF="/cgi-bin/man/man2html?2+request_key">request_key</A></B>(2)
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if the actual session keyring does not exist and is ignored otherwise.
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<P>
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A special serial number value,
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<B>KEY_SPEC_USER_SESSION_KEYRING</B>,
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is defined
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that can be used in lieu of the actual serial number of
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the calling process's user session keyring.
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<P>
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From the
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<B><A HREF="/cgi-bin/man/man2html?1+keyctl">keyctl</A></B>(1)
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utility, '<B>@us</B>' can be used instead of a numeric key ID in
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much the same way.
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<P>
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User session keyrings are independent of
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<B><A HREF="/cgi-bin/man/man2html?2+clone">clone</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+fork">fork</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+vfork">vfork</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+execve">execve</A></B>(2),
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and
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<B><A HREF="/cgi-bin/man/man2html?2+_exit">_exit</A></B>(2)
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excepting that the keyring is destroyed when the UID record is destroyed
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when the last process pinning it exits.
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<P>
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If a user session keyring does not exist when it is accessed,
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it will be created.
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<P>
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Rather than relying on the user session keyring,
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it is strongly recommended---especially if the process
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is running as root---that a
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<B><A HREF="/cgi-bin/man/man2html?7+session-keyring">session-keyring</A></B>(7)
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be set explicitly, for example by
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<B><A HREF="/cgi-bin/man/man2html?8+pam_keyinit">pam_keyinit</A></B>(8).
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<A NAME="lbAD"> </A>
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<H2>NOTES</H2>
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The user session keyring was added to support situations where
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a process doesn't have a session keyring,
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perhaps because it was created via a pathway that didn't involve PAM
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(e.g., perhaps it was a daemon started by
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<B><A HREF="/cgi-bin/man/man2html?8+inetd">inetd</A></B>(8)).
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In such a scenario, the user session keyring acts as a substitute for the
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<B><A HREF="/cgi-bin/man/man2html?7+session-keyring">session-keyring</A></B>(7).
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<A NAME="lbAE"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?1+keyctl">keyctl</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?3+keyctl">keyctl</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+keyrings">keyrings</A></B>(7),
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<B><A HREF="/cgi-bin/man/man2html?7+persistent-keyring">persistent-keyring</A></B>(7),
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<B><A HREF="/cgi-bin/man/man2html?7+process-keyring">process-keyring</A></B>(7),
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<B><A HREF="/cgi-bin/man/man2html?7+session-keyring">session-keyring</A></B>(7),
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<B><A HREF="/cgi-bin/man/man2html?7+thread-keyring">thread-keyring</A></B>(7),
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<B><A HREF="/cgi-bin/man/man2html?7+user-keyring">user-keyring</A></B>(7)
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<A NAME="lbAF"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">DESCRIPTION</A><DD>
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<DT id="3"><A HREF="#lbAD">NOTES</A><DD>
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<DT id="4"><A HREF="#lbAE">SEE ALSO</A><DD>
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<DT id="5"><A HREF="#lbAF">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:10 GMT, March 31, 2021
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</BODY>
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</HTML>
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