SSSD-SUDO(5) File Formats and Conventions SSSD-SUDO(5)
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).
TUNING THE PERFORMANCE
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.
1. Index LDAP attributes. Make sure that following LDAP attributes are
indexed: objectClass, cn, entryUSN or modifyTimestamp.
2. Set ldap_sudo_search_base. Set the search base to the container
that holds the sudo rules to limit the scope of the lookup.
3. Set full and smart refresh interval. 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
ldap_sudo_full_refresh_interval and ldap_sudo_smart_refresh_interval.
You may also consider disabling the smart refresh by setting
ldap_sudo_smart_refresh_interval = 0.
4. If you have large number of clients, you may consider increasing the
value of ldap_sudo_random_offset to distribute the load on the server
better.
SEE ALSO
sssd(8), sssd.conf(5), sssd-ldap(5), sssd-krb5(5), sssd-simple(5),
sssd-ipa(5), sssd-ad(5), sssd-files(5), sssd-sudo(5), sssd-session-
recording(5), sss_cache(8), sss_debuglevel(8), sss_obfuscate(8),
sss_seed(8), sssd_krb5_locator_plugin(8), sss_ssh_authorizedkeys(8),
sss_ssh_knownhostsproxy(8), sssd-ifp(5), pam_sss(8). sss_rpcidmapd(5)
sssd-systemtap(5)
AUTHORS
The SSSD upstream - https://github.com/SSSD/sssd/
SSSD 02/09/2025 SSSD-SUDO(5)
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