Integrate Identity with LDAP

Integrate Identity with LDAP

The OpenStack Identity service supports integration with existing LDAP directories for authentication and authorization services. LDAP back ends require initialization before configuring the OpenStack Identity service to work with it. For more information, see Setting up LDAP for use with Keystone.

When the OpenStack Identity service is configured to use LDAP back ends, you can split authentication (using the identity feature) and authorization (using the assignment feature). OpenStack Identity only supports read-only LDAP integration.

The identity feature enables administrators to manage users and groups by each domain or the OpenStack Identity service entirely.

The assignment feature enables administrators to manage project role authorization using the OpenStack Identity service SQL database, while providing user authentication through the LDAP directory.

Note

It is possible to isolate identity related information to LDAP in a deployment and keep resource information in a separate datastore. It is not possible to do the opposite, where resource information is stored in LDAP and identity information is stored in SQL. If the resource or assignment back ends are integrated with LDAP, the identity back end must also be integrated with LDAP.

Identity LDAP server set up

Important

If you are using SELinux (enabled by default on RHEL derivatives), then in order for the OpenStack Identity service to access LDAP servers, you must enable the authlogin_nsswitch_use_ldap boolean value for SELinux on the server running the OpenStack Identity service. To enable and make the option persistent across reboots, set the following boolean value as the root user:

# setsebool -P authlogin_nsswitch_use_ldap on

The Identity configuration is split into two separate back ends; identity (back end for users and groups), and assignments (back end for domains, projects, roles, role assignments). To configure Identity, set options in the /etc/keystone/keystone.conf file. See Integrate Identity back end with LDAP for Identity back end configuration examples. Modify these examples as needed.

To define the destination LDAP server

Define the destination LDAP server in the /etc/keystone/keystone.conf file:

[ldap]
url = ldap://localhost
user = dc=Manager,dc=example,dc=org
password = samplepassword
suffix = dc=example,dc=org

Multiple LDAP servers can be supplied to url to provide high-availability support for a single LDAP backend. To specify multiple LDAP servers, simply change the url option in the [ldap] section to be a list, separated by commas:

url = "ldap://localhost,ldap://backup.localhost"

Additional LDAP integration settings

Set these options in the /etc/keystone/keystone.conf file for a single LDAP server, or /etc/keystone/domains/keystone.DOMAIN_NAME.conf files for multiple back ends. Example configurations appear below each setting summary:

Query option

  • Use query_scope to control the scope level of data presented (search only the first level or search an entire sub-tree) through LDAP.

  • Use page_size to control the maximum results per page. A value of zero disables paging.

  • Use alias_dereferencing to control the LDAP dereferencing option for queries.

[ldap]
query_scope = sub
page_size = 0
alias_dereferencing = default
chase_referrals =

Debug

Use debug_level to set the LDAP debugging level for LDAP calls. A value of zero means that debugging is not enabled.

[ldap]
debug_level = 4095

This setting sets OPT_DEBUG_LEVEL in the underlying python library. This field is a bit mask (integer), and the possible flags are documented in the OpenLDAP manpages. Commonly used values include 255 and 4095, with 4095 being more verbose and 0 being disabled. We recommend consulting the documentation for your LDAP back end when using this option.

Warning

Enabling debug_level will negatively impact performance.

Connection pooling

Various LDAP back ends use a common LDAP module to interact with LDAP data. By default, a new connection is established for each LDAP operation. This is expensive when TLS support is enabled, which is a likely configuration in an enterprise setup. Reusing connections from a connection pool drastically reduces overhead of initiating a new connection for every LDAP operation.

Use use_pool to enable LDAP connection pooling. Configure the connection pool size, maximum retry, reconnect trials, timeout (-1 indicates indefinite wait) and lifetime in seconds.

[ldap]
use_pool = true
pool_size = 10
pool_retry_max = 3
pool_retry_delay = 0.1
pool_connection_timeout = -1
pool_connection_lifetime = 600

Connection pooling for end user authentication

LDAP user authentication is performed via an LDAP bind operation. In large deployments, user authentication can use up all available connections in a connection pool. OpenStack Identity provides a separate connection pool specifically for user authentication.

Use use_auth_pool to enable LDAP connection pooling for end user authentication. Configure the connection pool size and lifetime in seconds. Both use_pool and use_auth_pool must be enabled to pool connections for user authentication.

[ldap]
use_auth_pool = false
auth_pool_size = 100
auth_pool_connection_lifetime = 60

When you have finished the configuration, restart the OpenStack Identity service.

Warning

During the service restart, authentication and authorization are unavailable.

Integrate Identity back end with LDAP

The Identity back end contains information for users, groups, and group member lists. Integrating the Identity back end with LDAP allows administrators to use users and groups in LDAP.

Important

For OpenStack Identity service to access LDAP servers, you must define the destination LDAP server in the /etc/keystone/keystone.conf file. For more information, see Identity LDAP server set up.

To integrate one Identity back end with LDAP

  1. Enable the LDAP Identity driver in the /etc/keystone/keystone.conf file. This allows LDAP as an identity back end:

    [identity]
    #driver = sql
    driver = ldap
    
  2. Create the organizational units (OU) in the LDAP directory, and define the corresponding location in the /etc/keystone/keystone.conf file:

    [ldap]
    user_tree_dn = ou=Users,dc=example,dc=org
    user_objectclass = inetOrgPerson
    
    group_tree_dn = ou=Groups,dc=example,dc=org
    group_objectclass = groupOfNames
    

    Note

    These schema attributes are extensible for compatibility with various schemas. For example, this entry maps to the person attribute in Active Directory:

    user_objectclass = person
    

    Restart the OpenStack Identity service.

    Warning

    During service restart, authentication and authorization are unavailable.

To integrate multiple Identity back ends with LDAP

  1. Set the following options in the /etc/keystone/keystone.conf file:

    1. Enable the LDAP driver:

      [identity]
      #driver = sql
      driver = ldap
      
    2. Enable domain-specific drivers:

      [identity]
      domain_specific_drivers_enabled = True
      domain_config_dir = /etc/keystone/domains
      
  2. Restart the OpenStack Identity service.

    Warning

    During service restart, authentication and authorization are unavailable.

  3. List the domains using the dashboard, or the OpenStackClient CLI. Refer to the Command List for a list of OpenStackClient commands.

  4. Create domains using OpenStack dashboard, or the OpenStackClient CLI.

  5. For each domain, create a domain-specific configuration file in the /etc/keystone/domains directory. Use the file naming convention keystone.DOMAIN_NAME.conf, where DOMAIN_NAME is the domain name assigned in the previous step.

    Note

    The options set in the /etc/keystone/domains/keystone.DOMAIN_NAME.conf file will override options in the /etc/keystone/keystone.conf file.

  6. Define the destination LDAP server in the /etc/keystone/domains/keystone.DOMAIN_NAME.conf file. For example:

    [ldap]
    url = ldap://localhost
    user = dc=Manager,dc=example,dc=org
    password = samplepassword
    suffix = dc=example,dc=org
    
  7. Create the organizational units (OU) in the LDAP directories, and define their corresponding locations in the /etc/keystone/domains/keystone.DOMAIN_NAME.conf file. For example:

    [ldap]
    user_tree_dn = ou=Users,dc=example,dc=org
    user_objectclass = inetOrgPerson
    
    group_tree_dn = ou=Groups,dc=example,dc=org
    group_objectclass = groupOfNames
    

    Note

    These schema attributes are extensible for compatibility with various schemas. For example, this entry maps to the person attribute in Active Directory:

    user_objectclass = person
    
  8. Restart the OpenStack Identity service.

    Warning

    During service restart, authentication and authorization are unavailable.

Additional LDAP integration settings

Set these options in the /etc/keystone/keystone.conf file for a single LDAP server, or /etc/keystone/domains/keystone.DOMAIN_NAME.conf files for multiple back ends. Example configurations appear below each setting summary:

Filters

Use filters to control the scope of data presented through LDAP.

[ldap]
user_filter = (memberof=cn=openstack-users,ou=workgroups,dc=example,dc=org)
group_filter =
Identity attribute mapping

Mask account status values (include any additional attribute mappings) for compatibility with various directory services. Superfluous accounts are filtered with user_filter.

Setting attribute ignore to list of attributes stripped off on update.

For example, you can mask Active Directory account status attributes in the /etc/keystone/keystone.conf file:

[ldap]
user_id_attribute      = cn
user_name_attribute    = sn
user_mail_attribute    = mail
user_pass_attribute    = userPassword
user_enabled_attribute = userAccountControl
user_enabled_mask      = 2
user_enabled_invert    = false
user_enabled_default   = 512
user_default_project_id_attribute =
user_additional_attribute_mapping =

group_id_attribute     = cn
group_name_attribute   = ou
group_member_attribute = member
group_desc_attribute   = description
group_additional_attribute_mapping =

It is possible to model more complex LDAP schemas. For example, in the user object, the objectClass posixAccount from RFC2307 is very common. If this is the underlying objectClass, then the uid field should probably be uidNumber and the username field should be either uid or cn. The following illustrates the configuration:

[ldap]
user_id_attribute = uidNumber
user_name_attribute = cn
Enabled emulation

OpenStack Identity supports emulation for integrating with LDAP servers that do not provide an enabled attribute for users. This allows OpenStack Identity to advertise enabled attributes when the user entity in LDAP does not. The user_enabled_emulation option must be enabled and the user_enabled_emulation_dn option must be a valid LDAP group. Users in the group specified by user_enabled_emulation_dn will be marked as enabled. For example, the following will mark any user who is a member of the enabled_users group as enabled:

[ldap]
user_enabled_emulation = True
user_enabled_emulation_dn = cn=enabled_users,cn=groups,dc=openstack,dc=org

If the directory server has an enabled attribute, but it is not a boolean type, a mask can be used to convert it. This is useful when the enabled attribute is an integer value. The following configuration highlights the usage:

[ldap]
user_enabled_attribute = userAccountControl
user_enabled_mask = 2
user_enabled_default = 512

In this case, the attribute is an integer and the enabled attribute is listed in bit 1. If the mask configured user_enabled_mask is different from 0, it retrieves the attribute from user_enabled_attribute and performs an add operation with the user_enabled_mask. If the sum of the operation matches the mask, then the account is disabled.

The value of user_enabled_attribute is also saved before applying the add operation in enabled_nomask. This is done in case the user needs to be enabled or disabled. Lastly, setting user_enabled_default is needed in order to create a default value on the integer attribute (512 = NORMAL ACCOUNT in Active Directory).

When you have finished configuration, restart the OpenStack Identity service.

Warning

During service restart, authentication and authorization are unavailable.

Secure the OpenStack Identity service connection to an LDAP back end

We recommend securing all connections between OpenStack Identity and LDAP. The Identity service supports the use of TLS to encrypt LDAP traffic. Before configuring this, you must first verify where your certificate authority file is located. For more information, see the OpenStack Security Guide SSL introduction.

Once you verify the location of your certificate authority file:

To configure TLS encryption on LDAP traffic

  1. Open the /etc/keystone/keystone.conf configuration file.

  2. Find the [ldap] section.

  3. In the [ldap] section, set the use_tls configuration key to True. Doing so will enable TLS.

  4. Configure the Identity service to use your certificate authorities file. To do so, set the tls_cacertfile configuration key in the ldap section to the certificate authorities file’s path.

    Note

    You can also set the tls_cacertdir (also in the ldap section) to the directory where all certificate authorities files are kept. If both tls_cacertfile and tls_cacertdir are set, then the latter will be ignored.

  5. Specify what client certificate checks to perform on incoming TLS sessions from the LDAP server. To do so, set the tls_req_cert configuration key in the [ldap] section to demand, allow, or never:

    • demand - The LDAP server always receives certificate requests. The session terminates if no certificate is provided, or if the certificate provided cannot be verified against the existing certificate authorities file.

    • allow - The LDAP server always receives certificate requests. The session will proceed as normal even if a certificate is not provided. If a certificate is provided but it cannot be verified against the existing certificate authorities file, the certificate will be ignored and the session will proceed as normal.

    • never - A certificate will never be requested.

When you have finished configuration, restart the OpenStack Identity service.

Note

If you are unable to connect to LDAP via OpenStack Identity, or observe a SERVER DOWN error, set the TLS_CACERT in /etc/ldap/ldap.conf to the same value specified in the [ldap] tls_certificate section of keystone.conf.

On distributions that include openstack-config, you can configure TLS encryption on LDAP traffic by running the following commands instead.

# openstack-config --set /etc/keystone/keystone.conf \
  ldap use_tls True
# openstack-config --set /etc/keystone/keystone.conf \
  ldap tls_cacertfile ``CA_FILE``
# openstack-config --set /etc/keystone/keystone.conf \
  ldap tls_req_cert ``CERT_BEHAVIOR``

Where:

  • CA_FILE is the absolute path to the certificate authorities file that should be used to encrypt LDAP traffic.

  • CERT_BEHAVIOR specifies what client certificate checks to perform on an incoming TLS session from the LDAP server (demand, allow, or never).

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