Centralize LDAP config/filter logic

Centralize all LDAP config logic in `GitLab::LDAP::Config`. Previously,
some logic was in the Devise initializer and it was not honoring the
`user_filter`. If a user outside the configured `user_filter` signed
in, an account would be created but they would then be denied access.
Now that logic is centralized, the filter is honored and users outside
the filter are never created.

app/helpers/auth_helper.rb

@@ -3,7 +3,7 @@ module AuthHelper
   FORM_BASED_PROVIDERS = [/\Aldap/, 'crowd'].freeze
   def ldap_enabled?
-    Gitlab.config.ldap.enabled
+    Gitlab::LDAP::Config.enabled?
   end
   def omniauth_enabled?

changelogs/unreleased/user_filter_auth.yml

+---
+title: Centralize LDAP config/filter logic
+merge_request: 6606
+author: 

config/initializers/devise.rb

@@ -213,22 +213,9 @@ Devise.setup do |config|
   end
   if Gitlab::LDAP::Config.enabled?
-    Gitlab.config.ldap.servers.values.each do |server|
-      if server['allow_username_or_email_login']
-        email_stripping_proc = ->(name) {name.gsub(/@.*\z/, '')}
-      else
-        email_stripping_proc = ->(name) {name}
-      end
-
-      config.omniauth server['provider_name'],
-        host:     server['host'],
-        base:     server['base'],
-        uid:      server['uid'],
-        port:     server['port'],
-        method:   server['method'],
-        bind_dn:  server['bind_dn'],
-        password: server['password'],
-        name_proc: email_stripping_proc
+    Gitlab::LDAP::Config.providers.each do |provider|
+      ldap_config = Gitlab::LDAP::Config.new(provider)
+      config.omniauth(provider, ldap_config.omniauth_options)
     end
   end

lib/gitlab/ldap/adapter.rb

@@ -89,9 +89,7 @@ module Gitlab
       end
       def user_filter(filter = nil)
-        if config.user_filter.present?
-          user_filter = Net::LDAP::Filter.construct(config.user_filter)
-        end
+        user_filter = config.constructed_user_filter if config.user_filter.present?
         if user_filter && filter
           Net::LDAP::Filter.join(filter, user_filter)

lib/gitlab/ldap/authentication.rb

@@ -54,11 +54,9 @@ module Gitlab
         # Apply LDAP user filter if present
         if config.user_filter.present?
-          filter = Net::LDAP::Filter.join(
-            filter,
-            Net::LDAP::Filter.construct(config.user_filter)
-          )
+          filter = Net::LDAP::Filter.join(filter, config.constructed_user_filter)
         end
+
         filter
       end

lib/gitlab/ldap/config.rb

@@ -13,7 +13,7 @@ module Gitlab
       end
       def self.providers
-        servers.map {|server| server['provider_name'] }
+        servers.map { |server| server['provider_name'] }
       end
       def self.valid_provider?(provider)
@@ -38,13 +38,31 @@ module Gitlab
       end
       def adapter_options
-        {
-          host: options['host'],
-          port: options['port'],
-          encryption: encryption
-        }.tap do |options|
-          options.merge!(auth_options) if has_auth?
+        opts = base_options.merge(
+          encryption: encryption,
+        )
+
+        opts.merge!(auth_options) if has_auth?
+
+        opts
+      end
+
+      def omniauth_options
+        opts = base_options.merge(
+          base: base,
+          method: options['method'],
+          filter: omniauth_user_filter,
+          name_proc: name_proc
+        )
+
+        if has_auth?
+          opts.merge!(
+            bind_dn: options['bind_dn'],
+            password: options['password']
+          )
         end
+
+        opts
       end
       def base
@@ -68,6 +86,10 @@ module Gitlab
         options['user_filter']
       end
+      def constructed_user_filter
+        @constructed_user_filter ||= Net::LDAP::Filter.construct(user_filter)
+      end
+
       def group_base
         options['group_base']
       end
@@ -96,8 +118,27 @@ module Gitlab
         options['password'] || options['bind_dn']
       end
+      def allow_username_or_email_login
+        options['allow_username_or_email_login']
+      end
+
+      def name_proc
+        if allow_username_or_email_login
+          Proc.new { |name| name.gsub(/@.*\z/, '') }
+        else
+          Proc.new { |name| name }
+        end
+      end
+
       protected
+      def base_options
+        {
+          host: options['host'],
+          port: options['port']
+        }
+      end
+
       def base_config
         Gitlab.config.ldap
       end
@@ -126,6 +167,16 @@ module Gitlab
           }
         }
       end
+
+      def omniauth_user_filter
+        uid_filter = Net::LDAP::Filter.eq(uid, '%{username}')
+
+        if user_filter.present?
+          Net::LDAP::Filter.join(uid_filter, constructed_user_filter).to_s
+        else
+          uid_filter.to_s
+        end
+      end
     end
   end
 end

spec/lib/gitlab/ldap/config_spec.rb

@@ -19,6 +19,87 @@ describe Gitlab::LDAP::Config, lib: true do
     end
   end
+  describe '#adapter_options' do
+    it 'constructs basic options' do
+      stub_ldap_config(
+        options: {
+          'host'    => 'ldap.example.com',
+          'port'    => 386,
+          'method'  => 'plain'
+        }
+      )
+
+      expect(config.adapter_options).to eq(
+        host: 'ldap.example.com',
+        port: 386,
+        encryption: nil
+      )
+    end
+
+    it 'includes authentication options when auth is configured' do
+      stub_ldap_config(
+        options: {
+          'host'      => 'ldap.example.com',
+          'port'      => 686,
+          'method'    => 'ssl',
+          'bind_dn'   => 'uid=admin,dc=example,dc=com',
+          'password'  => 'super_secret'
+        }
+      )
+
+      expect(config.adapter_options).to eq(
+        host: 'ldap.example.com',
+        port: 686,
+        encryption: :simple_tls,
+        auth: {
+          method: :simple,
+          username: 'uid=admin,dc=example,dc=com',
+          password: 'super_secret'
+        }
+      )
+    end
+  end
+
+  describe '#omniauth_options' do
+    it 'constructs basic options' do
+      stub_ldap_config(
+        options: {
+          'host'    => 'ldap.example.com',
+          'port'    => 386,
+          'base'    => 'ou=users,dc=example,dc=com',
+          'method'  => 'plain',
+          'uid'     => 'uid'
+        }
+      )
+
+      expect(config.omniauth_options).to include(
+        host: 'ldap.example.com',
+        port: 386,
+        base: 'ou=users,dc=example,dc=com',
+        method: 'plain',
+        filter: '(uid=%{username})'
+      )
+      expect(config.omniauth_options.keys).not_to include(:bind_dn, :password)
+    end
+
+    it 'includes authentication options when auth is configured' do
+      stub_ldap_config(
+        options: {
+          'uid'         => 'sAMAccountName',
+          'user_filter' => '(memberOf=cn=group1,ou=groups,dc=example,dc=com)',
+          'bind_dn'     => 'uid=admin,dc=example,dc=com',
+          'password'    => 'super_secret'
+        }
+      )
+
+      expect(config.omniauth_options).to include(
+        filter: '(&(sAMAccountName=%{username})(memberOf=cn=group1,ou=groups,dc=example,dc=com))',
+        bind_dn: 'uid=admin,dc=example,dc=com',
+        password: 'super_secret'
+      )
+    end
+  end
+
   describe '#has_auth?' do
     it 'is true when password is set' do
       stub_ldap_config(