140 lines
4.8 KiB
XML
140 lines
4.8 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Copyright (c) 2013 Eric W. Biederman
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The name of the copyright holders or contributors may not be used to
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endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!-- SHADOW-CONFIG-HERE -->
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]>
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<refentry id='subuid.5'>
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<refmeta>
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<refentrytitle>subuid</refentrytitle>
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<manvolnum>5</manvolnum>
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<refmiscinfo class="sectdesc">File Formats and Conversions</refmiscinfo>
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<refmiscinfo class="source">shadow-utils</refmiscinfo>
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<refmiscinfo class="version">&SHADOW_UTILS_VERSION;</refmiscinfo>
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</refmeta>
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<refnamediv id='name'>
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<refname>subuid</refname>
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<refpurpose>the subordinate uid file</refpurpose>
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</refnamediv>
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<refsect1 id='description'>
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<title>DESCRIPTION</title>
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<para>
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Each line in <filename>/etc/subuid</filename> contains
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a user name and a range of subordinate user ids that user
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is allowed to use.
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This is specified with three fields delimited by colons
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(<quote>:</quote>).
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These fields are:
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</para>
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<itemizedlist mark='bullet'>
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<listitem>
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<para>login name or UID</para>
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</listitem>
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<listitem>
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<para>numerical subordinate user ID</para>
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</listitem>
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<listitem>
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<para>numerical subordinate user ID count</para>
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</listitem>
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</itemizedlist>
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<para>
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This file specifies the user IDs that ordinary users can use, with
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the <command>newuidmap</command> command, to configure uid mapping
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in a user namespace.
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</para>
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<para>
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Multiple ranges may be specified per user.
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</para>
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<para>
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When large number of entries (10000-100000 or more) are defined in
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<filename>/etc/subuid</filename>, parsing performance penalty will
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become noticeable. In this case it is recommended to use UIDs
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instead of login names. Benchmarks have shown speed-ups up to 20x.
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</para>
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</refsect1>
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<refsect1 id='files'>
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<title>FILES</title>
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<variablelist>
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<varlistentry>
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<term><filename>/etc/subuid</filename></term>
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<listitem>
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<para>Per user subordinate user IDs.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>/etc/subuid-</filename></term>
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<listitem>
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<para>Backup file for /etc/subuid.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id='see_also'>
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<title>SEE ALSO</title>
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<para>
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<citerefentry>
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<refentrytitle>login.defs</refentrytitle><manvolnum>5</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>newgidmap</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>newuidmap</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>newusers</refentrytitle><manvolnum>1</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>subgid</refentrytitle><manvolnum>5</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>useradd</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>userdel</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>usermod</refentrytitle><manvolnum>8</manvolnum>
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</citerefentry>,
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<citerefentry>
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<refentrytitle>user_namespaces</refentrytitle><manvolnum>7</manvolnum>
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</citerefentry>.
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</para>
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</refsect1>
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</refentry>
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