Ubuntu Manpage: sssd-sudo - Configuring sudo with the SSSD back end

Provided by: sssd-common_1.16.1-1ubuntu1.8_amd64

NAME

       sssd-sudo - Configuring sudo with the SSSD back end

DESCRIPTION

       This manual page describes how to configure sudo(8) to work with sssd(8) and how SSSD caches sudo rules.

CONFIGURING SUDO TO COOPERATE WITH SSSD

       To enable SSSD as a source for sudo rules, add sss to the sudoers entry in nsswitch.conf(5).

       For example, to configure sudo to first lookup rules in the standard sudoers(5) file (which should
       contain rules that apply to local users) and then in SSSD, the nsswitch.conf file should contain the
       following line:

           sudoers: files sss

       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
       sudoers.ldap(5).

       Note: in order to use netgroups or IPA hostgroups in sudo rules, you also need to correctly set
       nisdomainname(1) to your NIS domain name (which equals to IPA domain name when using hostgroups).

CONFIGURING SSSD TO FETCH SUDO RULES

       All configuration that is needed on SSSD side is to extend the list of services with "sudo" in [sssd]
       section of sssd.conf(5). To speed up the LDAP lookups, you can also set search base for sudo rules using
       ldap_sudo_search_base option.

       The following example shows how to configure SSSD to download sudo rules from an LDAP server.

           [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

       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.

       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.

THE SUDO RULE CACHING MECHANISM

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.

The smart refresh 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.

The full refresh 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.

The rules refresh 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.

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 sudoHost attribute:

• keyword ALL

• wildcard

• netgroup (in the form "+netgroup")

• hostname or fully qualified domain name of this machine

• one of the IP addresses of this machine

• one of the IP addresses of the network (in the form "address/mask")

There are many configuration options that can be used to adjust the behavior. Please refer to
"ldap_sudo_*" in sssd-ldap(5) and "sudo_*" in sssd.conf(5).

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