gitlab-org--gitlab-foss/doc/administration/auth/ldap.md

LDAP

GitLab integrates with LDAP to support user authentication. This integration works with most LDAP-compliant directory servers, including Microsoft Active Directory, Apple Open Directory, Open LDAP, and 389 Server. GitLab EE includes enhanced integration, including group membership syncing.

Security

GitLab assumes that LDAP users are not able to change their LDAP 'mail', 'email' or 'userPrincipalName' attribute. An LDAP user who is allowed to change their email on the LDAP server can potentially take over any account on your GitLab server.

We recommend against using LDAP integration if your LDAP users are allowed to change their 'mail', 'email' or 'userPrincipalName' attribute on the LDAP server.

User deletion

If a user is deleted from the LDAP server, they will be blocked in GitLab, as well. Users will be immediately blocked from logging in. However, there is an LDAP check cache time (sync time) of one hour (see note). This means users that are already logged in or are using Git over SSH will still be able to access GitLab for up to one hour. Manually block the user in the GitLab Admin area to immediately block all access.

Note

: GitLab EE supports a configurable sync time, with a default of one hour.

Configuration

To enable LDAP integration you need to add your LDAP server settings in /etc/gitlab/gitlab.rb or /home/git/gitlab/config/gitlab.yml.

There is a Rake task to check LDAP configuration. After configuring LDAP using the documentation below, see LDAP check Rake task for information on the LDAP check Rake task.

Note

: In GitLab EE, you can configure multiple LDAP servers to connect to one GitLab server.

Prior to version 7.4, GitLab used a different syntax for configuring LDAP integration. The old LDAP integration syntax still works but may be removed in a future version. If your gitlab.rb or gitlab.yml file contains LDAP settings in both the old syntax and the new syntax, only the old syntax will be used by GitLab.

The configuration inside gitlab_rails['ldap_servers'] below is sensitive to incorrect indentation. Be sure to retain the indentation given in the example. Copy/paste can sometimes cause problems.

Omnibus configuration

gitlab_rails['ldap_enabled'] = true
gitlab_rails['ldap_servers'] = YAML.load <<-EOS # remember to close this block with 'EOS' below
main: # 'main' is the GitLab 'provider ID' of this LDAP server
  ## label
  #
  # A human-friendly name for your LDAP server. It is OK to change the label later,
  # for instance if you find out it is too large to fit on the web page.
  #
  # Example: 'Paris' or 'Acme, Ltd.'
  label: 'LDAP'

  host: '_your_ldap_server'
  port: 389
  uid: 'sAMAccountName'
  method: 'plain' # "tls" or "ssl" or "plain"
  bind_dn: '_the_full_dn_of_the_user_you_will_bind_with'
  password: '_the_password_of_the_bind_user'

  # Set a timeout, in seconds, for LDAP queries. This helps avoid blocking
  # a request if the LDAP server becomes unresponsive.
  # A value of 0 means there is no timeout.
  timeout: 10

  # This setting specifies if LDAP server is Active Directory LDAP server.
  # For non AD servers it skips the AD specific queries.
  # If your LDAP server is not AD, set this to false.
  active_directory: true

  # If allow_username_or_email_login is enabled, GitLab will ignore everything
  # after the first '@' in the LDAP username submitted by the user on login.
  #
  # Example:
  # - the user enters 'jane.doe@example.com' and 'p@ssw0rd' as LDAP credentials;
  # - GitLab queries the LDAP server with 'jane.doe' and 'p@ssw0rd'.
  #
  # If you are using "uid: 'userPrincipalName'" on ActiveDirectory you need to
  # disable this setting, because the userPrincipalName contains an '@'.
  allow_username_or_email_login: false

  # To maintain tight control over the number of active users on your GitLab installation,
  # enable this setting to keep new users blocked until they have been cleared by the admin
  # (default: false).
  block_auto_created_users: false

  # Base where we can search for users
  #
  #   Ex. ou=People,dc=gitlab,dc=example
  #
  base: ''

  # Filter LDAP users
  #
  #   Format: RFC 4515 https://tools.ietf.org/search/rfc4515
  #   Ex. (employeeType=developer)
  #
  #   Note: GitLab does not support omniauth-ldap's custom filter syntax.
  #
  user_filter: ''

  # LDAP attributes that GitLab will use to create an account for the LDAP user.
  # The specified attribute can either be the attribute name as a string (e.g. 'mail'),
  # or an array of attribute names to try in order (e.g. ['mail', 'email']).
  # Note that the user's LDAP login will always be the attribute specified as `uid` above.
  attributes:
    # The username will be used in paths for the user's own projects
    # (like `gitlab.example.com/username/project`) and when mentioning
    # them in issues, merge request and comments (like `@username`).
    # If the attribute specified for `username` contains an email address,
    # the GitLab username will be the part of the email address before the '@'.
    username: ['uid', 'userid', 'sAMAccountName']
    email:    ['mail', 'email', 'userPrincipalName']

    # If no full name could be found at the attribute specified for `name`,
    # the full name is determined using the attributes specified for
    # `first_name` and `last_name`.
    name:       'cn'
    first_name: 'givenName'
    last_name:  'sn'

  ## EE only

  # Base where we can search for groups
  #
  #   Ex. ou=groups,dc=gitlab,dc=example
  #
  group_base: ''

  # The CN of a group containing GitLab administrators
  #
  #   Ex. administrators
  #
  #   Note: Not `cn=administrators` or the full DN
  #
  admin_group: ''

  # The LDAP attribute containing a user's public SSH key
  #
  #   Ex. ssh_public_key
  #
  sync_ssh_keys: false

# GitLab EE only: add more LDAP servers
# Choose an ID made of a-z and 0-9 . This ID will be stored in the database
# so that GitLab can remember which LDAP server a user belongs to.
# uswest2:
#   label:
#   host:
#   ....
EOS

Source configuration

Use the same format as gitlab_rails['ldap_servers'] for the contents under servers: in the example below:

production:
  # snip...
  ldap:
    enabled: false
    servers:
      main: # 'main' is the GitLab 'provider ID' of this LDAP server
        ## label
        #
        # A human-friendly name for your LDAP server. It is OK to change the label later,
        # for instance if you find out it is too large to fit on the web page.
        #
        # Example: 'Paris' or 'Acme, Ltd.'
        label: 'LDAP'
        # snip...

Using an LDAP filter to limit access to your GitLab server

If you want to limit all GitLab access to a subset of the LDAP users on your LDAP server, the first step should be to narrow the configured base. However, it is sometimes necessary to filter users further. In this case, you can set up an LDAP user filter. The filter must comply with RFC 4515.

Omnibus configuration

gitlab_rails['ldap_servers'] = YAML.load <<-EOS
main:
  # snip...
  user_filter: '(employeeType=developer)'
EOS

Source configuration

production:
  ldap:
    servers:
      main:
        # snip...
        user_filter: '(employeeType=developer)'

Tip: If you want to limit access to the nested members of an Active Directory group you can use the following syntax:

(memberOf:1.2.840.113556.1.4.1941:=CN=My Group,DC=Example,DC=com)

Please note that GitLab does not support the custom filter syntax used by omniauth-ldap.

Enabling LDAP sign-in for existing GitLab users

When a user signs in to GitLab with LDAP for the first time, and their LDAP email address is the primary email address of an existing GitLab user, then the LDAP DN will be associated with the existing user. If the LDAP email attribute is not found in GitLab's database, a new user is created.

In other words, if an existing GitLab user wants to enable LDAP sign-in for themselves, they should check that their GitLab email address matches their LDAP email address, and then sign into GitLab via their LDAP credentials.

Limitations

TLS Client Authentication

Not implemented by Net::LDAP. You should disable anonymous LDAP authentication and enable simple or SASL authentication. The TLS client authentication setting in your LDAP server cannot be mandatory and clients cannot be authenticated with the TLS protocol.

TLS Server Authentication

Not supported by GitLab's configuration options. When setting method: ssl, the underlying authentication method used by omniauth-ldap is simple_tls. This method establishes TLS encryption with the LDAP server before any LDAP-protocol data is exchanged but no validation of the LDAP server's SSL certificate is performed.

Troubleshooting

Debug LDAP user filter with ldapsearch

This example uses ldapsearch and assumes you are using ActiveDirectory. The following query returns the login names of the users that will be allowed to log in to GitLab if you configure your own user_filter.

ldapsearch -H ldaps://$host:$port -D "$bind_dn" -y bind_dn_password.txt  -b "$base" "$user_filter" sAMAccountName

• Variables beginning with a $ refer to a variable from the LDAP section of your configuration file.
• Replace ldaps:// with ldap:// if you are using the plain authentication method. Port 389 is the default ldap:// port and 636 is the default ldaps:// port.
• We are assuming the password for the bind_dn user is in bind_dn_password.txt.

Invalid credentials when logging in

• Make sure the user you are binding with has enough permissions to read the user's tree and traverse it.

• Check that the user_filter is not blocking otherwise valid users.

• Run the following check command to make sure that the LDAP settings are correct and GitLab can see your users:

  # For Omnibus installations
  sudo gitlab-rake gitlab:ldap:check
  
  # For installations from source
  sudo -u git -H bundle exec rake gitlab:ldap:check RAILS_ENV=production
  

Connection Refused

If you are getting 'Connection Refused' errors when trying to connect to the LDAP server please double-check the LDAP port and method settings used by GitLab. Common combinations are method: 'plain' and port: 389, OR method: 'ssl' and port: 636.

Login with valid credentials rejected

If there is an unexpected error while authenticating the user with the LDAP backend, the login is rejected and details about the error are logged to production.log.