Adding upstream version 252.22.upstream/252.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 349 insertions, 0 deletions

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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="pam_systemd" conditional='HAVE_PAM'>
+
+  <refentryinfo>
+    <title>pam_systemd</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>pam_systemd</refentrytitle>
+    <manvolnum>8</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>pam_systemd</refname>
+    <refpurpose>Register user sessions in the systemd login manager</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <para><filename>pam_systemd.so</filename></para>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><command>pam_systemd</command> registers user sessions with
+    the systemd login manager
+    <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+    and hence the systemd control group hierarchy.</para>
+
+    <para>The module also applies various resource management and runtime parameters to the new session, as
+    configured in the <ulink url="https://systemd.io/USER_RECORD">JSON User Records</ulink> of the user, when
+    one is defined.</para>
+
+    <para>On login, this module — in conjunction with <filename>systemd-logind.service</filename> — ensures the
+    following:</para>
+
+    <orderedlist>
+      <listitem><para>If it does not exist yet, the user runtime directory <filename>/run/user/$UID</filename> is
+      either created or mounted as new <literal>tmpfs</literal> file system with quota applied, and its ownership
+      changed to the user that is logging in.</para></listitem>
+
+      <listitem><para>The <varname>$XDG_SESSION_ID</varname> environment variable is initialized. If auditing is
+      available and <command>pam_loginuid.so</command> was run before this module (which is highly recommended), the
+      variable is initialized from the auditing session id (<filename>/proc/self/sessionid</filename>). Otherwise, an
+      independent session counter is used.</para></listitem>
+
+      <listitem><para>A new systemd scope unit is created for the session. If this is the first concurrent session of
+      the user, an implicit per-user slice unit below <filename>user.slice</filename> is automatically created and the
+      scope placed into it. An instance of the system service <filename>user@.service</filename>, which runs the
+      systemd user manager instance, is started.</para></listitem>
+
+      <listitem><para>The <literal>$TZ</literal>, <literal>$EMAIL</literal> and <literal>$LANG</literal>
+      environment variables are configured for the user, based on the respective data from the user's JSON
+      record (if it is defined). Moreover, any environment variables explicitly configured in the user record
+      are imported, and the umask, nice level, and resource limits initialized.</para></listitem>
+    </orderedlist>
+
+    <para>On logout, this module ensures the following:</para>
+
+    <orderedlist>
+      <listitem><para>If enabled in
+      <citerefentry><refentrytitle>logind.conf</refentrytitle>
+      <manvolnum>5</manvolnum></citerefentry> (<varname>KillUserProcesses=</varname>), all processes of the session are
+      terminated. If the last concurrent session of a user ends, the user's systemd instance will be terminated too,
+      and so will the user's slice unit.</para></listitem>
+
+      <listitem><para>If the last concurrent session of a user ends,
+      the user runtime directory <filename>/run/user/$UID</filename> and all its
+      contents are removed, too.</para></listitem>
+    </orderedlist>
+
+    <para>If the system was not booted up with systemd as init system,
+    this module does nothing and immediately returns
+    <constant>PAM_SUCCESS</constant>.</para>
+
+  </refsect1>
+
+  <refsect1>
+    <title>Options</title>
+
+    <para>The following options are understood:</para>
+
+    <variablelist class='pam-directives'>
+
+      <varlistentry>
+        <term><varname>class=</varname></term>
+
+        <listitem><para>Takes a string argument which sets the session class. The <varname>XDG_SESSION_CLASS</varname>
+        environment variable (see below) takes precedence. One of <literal>user</literal>, <literal>greeter</literal>,
+        <literal>lock-screen</literal> or <literal>background</literal>. See
+        <citerefentry><refentrytitle>sd_session_get_class</refentrytitle><manvolnum>3</manvolnum></citerefentry> for
+        details about the session class.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>type=</varname></term>
+
+        <listitem><para>Takes a string argument which sets the session type. The <varname>XDG_SESSION_TYPE</varname>
+        environment variable (see below) takes precedence. One of <literal>unspecified</literal>,
+        <literal>tty</literal>, <literal>x11</literal>, <literal>wayland</literal> or <literal>mir</literal>. See
+        <citerefentry><refentrytitle>sd_session_get_type</refentrytitle><manvolnum>3</manvolnum></citerefentry> for
+        details about the session type.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>desktop=</varname></term>
+
+        <listitem><para>Takes a single, short identifier string for the desktop environment. The
+        <varname>XDG_SESSION_DESKTOP</varname> environment variable (see below) takes precedence. This may be used to
+        indicate the session desktop used, where this applies and if this information is available. For example:
+        <literal>GNOME</literal>, or <literal>KDE</literal>. It is recommended to use the same identifiers and
+        capitalization as for <varname>$XDG_CURRENT_DESKTOP</varname>, as defined by the <ulink
+        url="https://standards.freedesktop.org/desktop-entry-spec/latest/">Desktop Entry
+        Specification</ulink>. (However, note that the option only takes a single item, and not a colon-separated list
+        like <varname>$XDG_CURRENT_DESKTOP</varname>.) See
+        <citerefentry><refentrytitle>sd_session_get_desktop</refentrytitle><manvolnum>3</manvolnum></citerefentry> for
+        further details.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>debug</varname><optional>=</optional></term>
+
+        <listitem><para>Takes an optional boolean argument. If yes or without the argument, the module will log
+        debugging information as it operates.</para></listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Module Types Provided</title>
+
+    <para>Only <option>session</option> is provided.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Environment</title>
+
+    <para>The following environment variables are initialized by the module and available to the processes of the
+    user's session:</para>
+
+    <variablelist class='environment-variables'>
+      <varlistentry>
+        <term><varname>$XDG_SESSION_ID</varname></term>
+
+        <listitem><para>A short session identifier, suitable to be used in filenames. The string itself should be
+        considered opaque, although often it is just the audit session ID as reported by
+        <filename>/proc/self/sessionid</filename>. Each ID will be assigned only once during machine uptime. It may
+        hence be used to uniquely label files or other resources of this session. Combine this ID with the boot
+        identifier, as returned by
+        <citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>, for a
+        globally unique identifier.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>$XDG_RUNTIME_DIR</varname></term>
+
+        <listitem><para>Path to a user-private user-writable directory
+        that is bound to the user login time on the machine. It is
+        automatically created the first time a user logs in and
+        removed on the user's final logout. If a user logs in twice at
+        the same time, both sessions will see the same
+        <varname>$XDG_RUNTIME_DIR</varname> and the same contents. If
+        a user logs in once, then logs out again, and logs in again,
+        the directory contents will have been lost in between, but
+        applications should not rely on this behavior and must be able
+        to deal with stale files. To store session-private data in
+        this directory, the user should include the value of
+        <varname>$XDG_SESSION_ID</varname> in the filename. This
+        directory shall be used for runtime file system objects such
+        as <constant>AF_UNIX</constant> sockets, FIFOs, PID files and
+        similar. It is guaranteed that this directory is local and
+        offers the greatest possible file system feature set the
+        operating system provides. For further details, see the <ulink
+        url="https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
+        Base Directory Specification</ulink>. <varname>$XDG_RUNTIME_DIR</varname>
+        is not set if the current user is not the original user of the session.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>$TZ</varname></term>
+        <term><varname>$EMAIL</varname></term>
+        <term><varname>$LANG</varname></term>
+
+        <listitem><para>If a JSON user record is known for the user logging in these variables are
+        initialized from the respective data in the record.</para></listitem>
+      </varlistentry>
+
+    </variablelist>
+
+    <para>The following environment variables are read by the module and may be used by the PAM service to pass
+    metadata to the module. If these variables are not set when the PAM module is invoked but can be determined
+    otherwise they are set by the module, so that these variables are initialized for the session and applications if
+    known at all.</para>
+
+    <variablelist class='environment-variables'>
+      <varlistentry>
+        <term><varname>$XDG_SESSION_TYPE</varname></term>
+
+        <listitem><para>The session type. This may be used instead of <varname>type=</varname> on the module parameter
+        line, and is usually preferred.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>$XDG_SESSION_CLASS</varname></term>
+
+        <listitem><para>The session class. This may be used instead of <varname>class=</varname> on the module parameter
+        line, and is usually preferred.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>$XDG_SESSION_DESKTOP</varname></term>
+
+        <listitem><para>The desktop identifier. This may be used instead of <varname>desktop=</varname> on the module
+        parameter line, and is usually preferred.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>$XDG_SEAT</varname></term>
+
+        <listitem><para>The seat name the session shall be registered
+        for, if any.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>$XDG_VTNR</varname></term>
+
+        <listitem><para>The VT number the session shall be registered
+        for, if any. (Only applies to seats with a VT available, such
+        as <literal>seat0</literal>)</para></listitem>
+      </varlistentry>
+    </variablelist>
+
+    <para>If not set, <command>pam_systemd</command> will initialize
+    <varname>$XDG_SEAT</varname> and <varname>$XDG_VTNR</varname>
+    based on the <varname>$DISPLAY</varname> variable (if the latter is set).</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Session limits</title>
+
+    <para>PAM modules earlier in the stack, that is those that come before <command>pam_systemd.so</command>,
+    can set session scope limits using the PAM context objects. The data for these objects is provided as <constant>NUL</constant>-terminated C strings
+    and maps directly to the respective unit resource control directives. Note that these limits apply to individual sessions of the user,
+    they do not apply to all user processes as a combined whole. In particular, the per-user <command>user@.service</command> unit instance,
+    which runs the <command>systemd --user</command> manager process and its children, and is tracked outside of any session, being shared
+    by all the user's sessions, is not covered by these limits.
+    </para>
+
+    <para> See
+    <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information about the resources.
+    Also, see <citerefentry project='man-pages'><refentrytitle>pam_set_data</refentrytitle><manvolnum>3</manvolnum></citerefentry> for additional information about how to set
+    the context objects.
+    </para>
+
+    <variablelist class='pam-directives'>
+      <varlistentry>
+        <term><varname>systemd.memory_max=</varname></term>
+
+        <listitem><para>Sets unit <varname>MemoryMax=</varname>.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>systemd.tasks_max=</varname></term>
+
+        <listitem><para>Sets unit <varname>TasksMax=</varname>.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>systemd.cpu_weight=</varname></term>
+
+        <listitem><para>Sets unit <varname>CPUWeight=</varname>.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>systemd.io_weight=</varname></term>
+
+        <listitem><para>Sets unit <varname>IOWeight=</varname>.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>systemd.runtime_max_sec=</varname></term>
+
+        <listitem><para>Sets unit <varname>RuntimeMaxSec=</varname>.</para></listitem>
+      </varlistentry>
+    </variablelist>
+
+    <para>Example data as can be provided from an another PAM module:
+      <programlisting>
+pam_set_data(handle, "systemd.memory_max", (void *)"200M", cleanup);
+pam_set_data(handle, "systemd.tasks_max",  (void *)"50",   cleanup);
+pam_set_data(handle, "systemd.cpu_weight", (void *)"100",  cleanup);
+pam_set_data(handle, "systemd.io_weight",  (void *)"340",  cleanup);
+pam_set_data(handle, "systemd.runtime_max_sec", (void *)"3600", cleanup);
+      </programlisting>
+    </para>
+
+  </refsect1>
+
+  <refsect1>
+    <title>Example</title>
+
+    <para>Here's an example PAM configuration fragment that allows users sessions to be managed by
+    <filename>systemd-logind.service</filename>:</para>
+
+    <programlisting>#%PAM-1.0
+auth      sufficient pam_unix.so
+-auth     sufficient pam_systemd_home.so
+auth      required   pam_deny.so
+
+account   required   pam_nologin.so
+-account  sufficient pam_systemd_home.so
+account   sufficient pam_unix.so
+account   required   pam_permit.so
+
+-password sufficient pam_systemd_home.so
+password  sufficient pam_unix.so sha512 shadow try_first_pass
+password  required   pam_deny.so
+
+-session  optional   pam_keyinit.so revoke
+-session  optional   pam_loginuid.so
+-session  optional   pam_systemd_home.so
+<command>-session  optional   pam_systemd.so</command>
+session   required   pam_unix.so</programlisting>
+  </refsect1>
+
+  <refsect1>
+    <title>See Also</title>
+    <para>
+      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd-logind.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>pam_systemd_home</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>pam.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>pam.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>pam_loginuid</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>