s3:idmap: add a new ID mapping module autorid

This is an initial implementation of the idmap_autorid module.
It works similar to the idmap_rid module but requires less
configuration. It will automatically pick ranges for each domain,
so you do not have to bother any more about adding an idmap
configuration for all of the domains in the forest.

This is very easy to use and to configure and much more
deterministic and faster than idmap_tdb, the typical choice
of Samba users up to now.

1 files changed, 134 insertions, 0 deletions

diff --git a/docs-xml/manpages-3/idmap_autorid.8.xml b/docs-xml/manpages-3/idmap_autorid.8.xml
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+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
+<refentry id="idmap_autorid.8">
+
+<refmeta>
+	<refentrytitle>idmap_autorid</refentrytitle>
+	<manvolnum>8</manvolnum>
+	<refmiscinfo class="source">Samba</refmiscinfo>
+	<refmiscinfo class="manual">System Administration tools</refmiscinfo>
+	<refmiscinfo class="version">3.6</refmiscinfo>
+</refmeta>
+
+
+<refnamediv>
+	<refname>idmap_autorid</refname>
+	<refpurpose>Samba's idmap_autorid Backend for Winbind</refpurpose>
+</refnamediv>
+
+<refsynopsisdiv>
+	<title>DESCRIPTION</title>
+	<para>The idmap_autorid backend provides a way to use an algorithmic
+	mapping scheme to map UIDs/GIDs and SIDs that is more deterministic
+	than idmap_tdb and easier to configure than idmap_rid.</para>
+	<para>The module works similar to idmap_rid, but it automatically
+	configures the range to be used for each domain, so there is no need
+	to specify a specific range for each domain in the forest, the only
+	configuration that is needed is the range of uid/gids that shall
+	be used for user/group mappings and an optional size of the ranges
+	to be used.</para>
+	<para>The mappings of which domain is mapped to which range is stored
+	in autorid.tdb, thus you should backup this database regularly.</para>
+	<para>Due to the algorithm being used, it is the module that is
+	most easy to use as it only requires a minimal configuration.</para>
+</refsynopsisdiv>
+
+<refsect1>
+	<title>IDMAP OPTIONS</title>
+
+	<variablelist>
+		<varlistentry>
+		<term>rangesize = numberofidsperdomain</term>
+		<listitem><para>
+			Defines the available number of uids/gids per domain. The
+			minimum needed value is 2000. SIDs with RIDs larger than this
+			value cannot be mapped, are ignored and the corresponding map
+			is discarded. Choose this value carefully, as this should
+			not be changed after the first ranges for domains have been
+			defined, otherwise mappings between domains will get intermixed
+			leading to unpredictable results. Please note that RIDs in Windows
+			Domains usually start with 500 for builtin users and 1000
+			for regular users. As the parameter cannot be changed later, please
+			plan accordingly for your expected number of users in a domain
+			with safety margins.
+		</para>
+		<para>The default value is 100000.</para>
+		</listitem>
+		</varlistentry>
+	</variablelist>
+</refsect1>
+
+<refsect1>
+	<title>THE MAPPING FORMULAS</title>
+	<para>
+		The Unix ID for a RID is calculated this way:
+		<programlisting>
+			ID = IDMAP UID LOW VALUE + DOMAINRANGENUMBER * RANGESIZE + RID
+		</programlisting>
+	</para>
+	<para>
+		Correspondingly, the formula for calculating the RID for a
+		given Unix ID is this:
+		<programlisting>
+			RID = ID - IDMAP UID LOW VALUE - DOMAINRANGENUMBER * RANGESIZE
+		</programlisting>
+	</para>
+</refsect1>
+
+<refsect1>
+	<title>EXAMPLES</title>
+	<para>
+		This example shows you the minimal configuration that will
+		work for the principial domain and 19 trusted domains.
+	</para>
+
+	<programlisting>
+	[global]
+	security = ads
+	workgroup = CUSTOMER
+	realm = CUSTOMER.COM
+
+	idmap backend = autorid
+	idmap uid = 1000000-1999999
+	idmap gid = 1000000-1999999
+
+	</programlisting>
+
+	<para>
+		This example shows how to configure idmap_autorid as default
+		for all domains with a potentially large amount of users
+		plus a specific configuration for a trusted domain
+		that uses the SFU mapping scheme. Please note that idmap uid/gid
+		ranges and sfu ranges are not allowed to overlap.
+	</para>
+
+	<programlisting>
+	[global]
+	security = ads
+	workgroup = CUSTOMER
+	realm = CUSTOMER.COM
+
+	idmap backend = autorid
+	autorid:rangesize = 1000000
+	idmap uid = 1000000-19999999
+	idmap gid = 1000000-19999999
+
+	idmap config TRUSTED : backend  = ad
+	idmap config TRUSTED : range    = 50000 - 99999
+	idmap config TRUSTED : schema_mode = sfu
+	</programlisting>
+
+</refsect1>
+
+<refsect1>
+	<title>AUTHOR</title>
+
+	<para>
+	The original Samba software and related utilities
+	were created by Andrew Tridgell. Samba is now developed
+	by the Samba Team as an Open Source project similar
+	to the way the Linux kernel is developed.
+	</para>
+</refsect1>
+
+</refentry>