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.

7 files changed, 150 insertions, 31 deletions

diff --git a/app/helpers/auth_helper.rb b/app/helpers/auth_helper.rb
index cd4d778e508..92bac149313 100644
--- a/app/helpers/auth_helper.rb
+++ b/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?
diff --git a/changelogs/unreleased/user_filter_auth.yml b/changelogs/unreleased/user_filter_auth.yml
new file mode 100644
index 00000000000..e4071e22e5e
--- /dev/null
+++ b/changelogs/unreleased/user_filter_auth.yml
@@ -0,0 +1,4 @@
+---
+title: Centralize LDAP config/filter logic
+merge_request: 6606
+author: 
diff --git a/config/initializers/devise.rb b/config/initializers/devise.rb
index a0a8f88584c..f06c4d4ecf2 100644
--- a/config/initializers/devise.rb
+++ b/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
 
diff --git a/lib/gitlab/ldap/adapter.rb b/lib/gitlab/ldap/adapter.rb
index 8b38cfaefb6..7b05290e5cc 100644
--- a/lib/gitlab/ldap/adapter.rb
+++ b/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)
diff --git a/lib/gitlab/ldap/authentication.rb b/lib/gitlab/ldap/authentication.rb
index bad683c6511..4745311402c 100644
--- a/lib/gitlab/ldap/authentication.rb
+++ b/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
 
diff --git a/lib/gitlab/ldap/config.rb b/lib/gitlab/ldap/config.rb
index 6ea069d26df..de52ef3fc65 100644
--- a/lib/gitlab/ldap/config.rb
+++ b/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
diff --git a/spec/lib/gitlab/ldap/config_spec.rb b/spec/lib/gitlab/ldap/config_spec.rb
index f5ebe703083..1a6803e01c3 100644
--- a/spec/lib/gitlab/ldap/config_spec.rb
+++ b/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(