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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE reference PUBLIC "-//OASIS//DTD DocBook V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<reference>
<title>SSSD Manual pages</title>
<refentry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/upstream.xml" />
<refmeta>
<refentrytitle>sssd-sudo</refentrytitle>
<manvolnum>5</manvolnum>
<refmiscinfo class="manual">File Formats and Conventions</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>sssd-sudo</refname>
<refpurpose>Configuring sudo with the SSSD back end</refpurpose>
</refnamediv>
<refsect1 id='description'>
<title>DESCRIPTION</title>
<para>
This manual page describes how to configure
<citerefentry>
<refentrytitle>sudo</refentrytitle>
<manvolnum>8</manvolnum>
</citerefentry> to work with
<citerefentry>
<refentrytitle>sssd</refentrytitle>
<manvolnum>8</manvolnum>
</citerefentry> and how SSSD caches sudo rules.
</para>
</refsect1>
<refsect1 id='sudo'>
<title>Configuring sudo to cooperate with SSSD</title>
<para>
To enable SSSD as a source for sudo rules, add
<emphasis>sss</emphasis> to the <emphasis>sudoers</emphasis> entry
in
<citerefentry>
<refentrytitle>nsswitch.conf</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry>.
</para>
<para>
For example, to configure sudo to first lookup rules in the standard
<citerefentry>
<refentrytitle>sudoers</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry> file (which should contain rules that apply to
local users) and then in SSSD, the nsswitch.conf file should contain
the following line:
</para>
<para>
<programlisting>
sudoers: files sss
</programlisting>
</para>
<para>
More information about configuring the sudoers search order from the
nsswitch.conf file as well as information about the LDAP schema that
is used to store sudo rules in the directory can be found in
<citerefentry>
<refentrytitle>sudoers.ldap</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry>.
</para>
<para>
<emphasis>Note</emphasis>: in order to use netgroups or IPA
hostgroups in sudo rules, you also need to correctly set
<citerefentry>
<refentrytitle>nisdomainname</refentrytitle>
<manvolnum>1</manvolnum>
</citerefentry>
to your NIS domain name (which equals to IPA domain name when
using hostgroups).
</para>
</refsect1>
<refsect1 id='sssd'>
<title>Configuring SSSD to fetch sudo rules</title>
<para>
All configuration that is needed on SSSD side is to extend the list
of <emphasis>services</emphasis> with "sudo" in [sssd] section of
<citerefentry>
<refentrytitle>sssd.conf</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry>. To speed up the LDAP lookups, you can also set
search base for sudo rules using
<emphasis>ldap_sudo_search_base</emphasis> option.
</para>
<para>
The following example shows how to configure SSSD to download sudo
rules from an LDAP server.
</para>
<para>
<programlisting>
[sssd]
config_file_version = 2
services = nss, pam, sudo
domains = EXAMPLE
[domain/EXAMPLE]
id_provider = ldap
sudo_provider = ldap
ldap_uri = ldap://example.com
ldap_sudo_search_base = ou=sudoers,dc=example,dc=com
</programlisting>
<phrase condition="have_systemd">
It's important to note that on platforms where systemd is supported
there's no need to add the "sudo" provider to the list of services,
as it became optional. However, sssd-sudo.socket must be enabled
instead.
</phrase>
</para>
<para>
When SSSD is configured to use IPA as the ID provider, the
sudo provider is automatically enabled. The sudo search base is
configured to use the IPA native LDAP tree (cn=sudo,$SUFFIX).
If any other search base is defined in sssd.conf, this value will be
used instead. The compat tree (ou=sudoers,$SUFFIX) is no longer
required for IPA sudo functionality.
</para>
</refsect1>
<refsect1 id='cache'>
<title>The SUDO rule caching mechanism</title>
<para>
The biggest challenge, when developing sudo support in SSSD, was to
ensure that running sudo with SSSD as the data source provides the
same user experience and is as fast as sudo but keeps providing
the most current set of rules as possible. To satisfy these
requirements, SSSD uses three kinds of updates. They are referred to
as full refresh, smart refresh and rules refresh.
</para>
<para>
The <emphasis>smart refresh</emphasis> periodically downloads rules
that are new or were modified after the last update. Its primary
goal is to keep the database growing by fetching only small
increments that do not generate large amounts of network traffic.
</para>
<para>
The <emphasis>full refresh</emphasis> simply deletes all sudo rules
stored in the cache and replaces them with all rules that are stored
on the server. This is used to keep the cache consistent by removing
every rule which was deleted from the server. However, full refresh
may produce a lot of traffic and thus it should be run only
occasionally depending on the size and stability of the sudo rules.
</para>
<para>
The <emphasis>rules refresh</emphasis> ensures that we do not grant
the user more permission than defined. It is triggered each time the
user runs sudo. Rules refresh will find all rules that apply to this
user, check their expiration time and redownload them if expired.
In the case that any of these rules are missing on the server, the
SSSD will do an out of band full refresh because more rules
(that apply to other users) may have been deleted.
</para>
<para>
If enabled, SSSD will store only rules that can be applied to this
machine. This means rules that contain one of the following values
in <emphasis>sudoHost</emphasis> attribute:
</para>
<itemizedlist>
<listitem>
<para>
keyword ALL
</para>
</listitem>
<listitem>
<para>
wildcard
</para>
</listitem>
<listitem>
<para>
netgroup (in the form "+netgroup")
</para>
</listitem>
<listitem>
<para>
hostname or fully qualified domain name of this machine
</para>
</listitem>
<listitem>
<para>
one of the IP addresses of this machine
</para>
</listitem>
<listitem>
<para>
one of the IP addresses of the network
(in the form "address/mask")
</para>
</listitem>
</itemizedlist>
<para>
There are many configuration options that can be used to adjust
the behavior. Please refer to "ldap_sudo_*" in
<citerefentry>
<refentrytitle>sssd-ldap</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry> and "sudo_*" in
<citerefentry>
<refentrytitle>sssd.conf</refentrytitle>
<manvolnum>5</manvolnum>
</citerefentry>.
</para>
</refsect1>
<refsect1 id='performance'>
<title>Tuning the performance</title>
<para>
SSSD uses different kinds of mechanisms with more or less complex
LDAP filters to keep the cached sudo rules up to date. The default
configuration is set to values that should satisfy most of our
users, but the following paragraphs contain few tips on how to fine-
tune the configuration to your requirements.
</para>
<para>
1. <emphasis>Index LDAP attributes</emphasis>. Make sure that
following LDAP attributes are indexed: objectClass, cn, entryUSN or
modifyTimestamp.
</para>
<para>
2. <emphasis>Set ldap_sudo_search_base</emphasis>. Set the search
base to the container that holds the sudo rules to limit the scope
of the lookup.
</para>
<para>
3. <emphasis>Set full and smart refresh interval</emphasis>. If your
sudo rules do not change often and you do not require quick update
of cached rules on your clients, you may consider increasing the
<emphasis>ldap_sudo_full_refresh_interval</emphasis> and
<emphasis>ldap_sudo_smart_refresh_interval</emphasis>. You may also
consider disabling the smart refresh by setting
<emphasis>ldap_sudo_smart_refresh_interval = 0</emphasis>.
</para>
<para>
4. If you have large number of clients, you may consider increasing
the value of <emphasis>ldap_sudo_random_offset</emphasis> to
distribute the load on the server better.
</para>
</refsect1>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/seealso.xml" />
</refentry>
</reference>
|
