nss: add new "nss-systemd" NSS module for mapping dynamic users

With this NSS module all dynamic service users will be resolvable via NSS like
any real user.

4 files changed, 117 insertions, 7 deletions

diff --git a/man/nss-myhostname.xml b/man/nss-myhostname.xml
index a920ec334f..b1daaba02b 100644
--- a/man/nss-myhostname.xml
+++ b/man/nss-myhostname.xml
@@ -106,8 +106,8 @@
     <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
     <command>nss-myhostname</command> correctly:</para>
 
-<programlisting>passwd:         compat mymachines
-group:          compat mymachines
+<programlisting>passwd:         compat mymachines systemd
+group:          compat mymachines systemd
 shadow:         compat
 
 hosts:          files mymachines resolve <command>myhostname</command>
@@ -138,6 +138,7 @@ netgroup:       nis</programlisting>
     <title>See Also</title>
     <para>
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
diff --git a/man/nss-mymachines.xml b/man/nss-mymachines.xml
index ec047449bf..a70119e256 100644
--- a/man/nss-mymachines.xml
+++ b/man/nss-mymachines.xml
@@ -82,8 +82,8 @@
     <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
     <command>nss-mymachines</command> correctly:</para>
 
-    <programlisting>passwd:         compat <command>mymachines</command>
-group:          compat <command>mymachines</command>
+    <programlisting>passwd:         compat <command>mymachines</command> systemd
+group:          compat <command>mymachines</command> systemd
 shadow:         compat
 
 hosts:          files <command>mymachines</command> resolve myhostname
@@ -103,6 +103,7 @@ netgroup:       nis</programlisting>
     <para>
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
diff --git a/man/nss-resolve.xml b/man/nss-resolve.xml
index d9e56453e8..e6cc1d982a 100644
--- a/man/nss-resolve.xml
+++ b/man/nss-resolve.xml
@@ -81,8 +81,8 @@
     <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables <command>nss-resolve</command>
     correctly:</para>
 
-<programlisting>passwd:         compat mymachines
-group:          compat mymachines
+<programlisting>passwd:         compat mymachines systemd
+group:          compat mymachines systemd
 shadow:         compat
 
 hosts:          files mymachines <command>resolve</command> myhostname
@@ -102,8 +102,9 @@ netgroup:       nis</programlisting>
     <para>
       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>systemd-resolved</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
-      <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
       <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
     </para>
   </refsect1>
diff --git a/man/nss-systemd.xml b/man/nss-systemd.xml
new file mode 100644
index 0000000000..4228372e51
--- /dev/null
+++ b/man/nss-systemd.xml
@@ -0,0 +1,107 @@
+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="nss-systemd">
+
+  <refentryinfo>
+    <title>nss-systemd</title>
+    <productname>systemd</productname>
+
+    <authorgroup>
+      <author>
+        <contrib>Developer</contrib>
+        <firstname>Lennart</firstname>
+        <surname>Poettering</surname>
+        <email>lennart@poettering.net</email>
+      </author>
+    </authorgroup>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>nss-systemd</refentrytitle>
+    <manvolnum>8</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>nss-systemd</refname>
+    <refname>libnss_systemd.so.2</refname>
+    <refpurpose>Provide UNIX user and group name resolution for dynamic users and groups.</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <para><filename>libnss_systemd.so.2</filename></para>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><command>nss-systemd</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of the
+    GNU C Library (<command>glibc</command>), providing UNIX user and group name resolution for dynamic users and
+    groups allocated through the <varname>DynamicUser=</varname> option in systemd unit files. See
+    <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details on
+    this option.</para>
+
+    <para>To activate the NSS module, add <literal>systemd</literal> to the lines starting with
+    <literal>passwd:</literal> and <literal>group:</literal> in <filename>/etc/nsswitch.conf</filename>.</para>
+
+    <para>It is recommended to place <literal>systemd</literal> after the <literal>files</literal> or
+    <literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines so that
+    <filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Example</title>
+
+    <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
+    <command>nss-systemd</command> correctly:</para>
+
+    <programlisting>passwd:         compat mymachines <command>systemd</command>
+group:          compat mymachines <command>systemd</command>
+shadow:         compat
+
+hosts:          files mymachines resolve myhostname
+networks:       files
+
+protocols:      db files
+services:       db files
+ethers:         db files
+rpc:            db files
+
+netgroup:       nis</programlisting>
+
+  </refsect1>
+
+  <refsect1>
+    <title>See Also</title>
+    <para>
+      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>