Enforce authorizations for non-nullable fields

This makes sure we also enforce authorizations for non-nullable
fields.

We are defining our authorizations on the unwrapped
types (Repository). But when a type like that is presented in a
non-nullable field, it's type is different (Repository!). The
non-nullable type would not have the authorization metadata.

This makes sure we check the metadata on the unwrapped type for
finding authorizations.

app/graphql/types/project_type.rb

@@ -74,7 +74,7 @@ module Types
           null: true,
           resolve: -> (obj, _args, _ctx) { Gitlab::Graphql::Loaders::BatchProjectStatisticsLoader.new(obj.id).find }
 
-    field :repository, Types::RepositoryType, null: false
+    field :repository, Types::RepositoryType, null: true
 
     field :merge_requests,
           Types::MergeRequestType.connection_type,

app/policies/repository_policy.rb

+# frozen_string_literal: true
+
+class RepositoryPolicy < BasePolicy
+  delegate { @subject.project }
+end

changelogs/unreleased/security-bvl-enforce-graphql-type-authorization.yml

+---
+title: Add missing authorizations in GraphQL
+merge_request:
+author:
+type: security

lib/gitlab/graphql/authorize/authorize_field_service.rb

@@ -39,6 +39,8 @@ module Gitlab
             type = node_type_for_basic_connection(type)
           end
 
+          type = type.unwrap if type.kind.non_null?
+
           Array.wrap(type.metadata[:authorize])
         end
 

spec/lib/gitlab/graphql/authorize/authorize_field_service_spec.rb

@@ -7,35 +7,39 @@ require 'spec_helper'
 describe Gitlab::Graphql::Authorize::AuthorizeFieldService do
   def type(type_authorizations = [])
     Class.new(Types::BaseObject) do
-      graphql_name "TestType"
+      graphql_name 'TestType'
 
       authorize type_authorizations
     end
   end
 
-  def type_with_field(field_type, field_authorizations = [], resolved_value = "Resolved value")
+  def type_with_field(field_type, field_authorizations = [], resolved_value = 'Resolved value', **options)
     Class.new(Types::BaseObject) do
-      graphql_name "TestTypeWithField"
-      field :test_field, field_type, null: true, authorize: field_authorizations, resolve: -> (_, _, _) { resolved_value}
+      graphql_name 'TestTypeWithField'
+      options.reverse_merge!(null: true)
+      field :test_field, field_type,
+            authorize: field_authorizations,
+            resolve: -> (_, _, _) { resolved_value },
+            **options
     end
   end
 
   let(:current_user) { double(:current_user) }
   subject(:service) { described_class.new(field) }
 
-  describe "#authorized_resolve" do
-    let(:presented_object) { double("presented object") }
-    let(:presented_type) { double("parent type", object: presented_object) }
+  describe '#authorized_resolve' do
+    let(:presented_object) { double('presented object') }
+    let(:presented_type) { double('parent type', object: presented_object) }
     subject(:resolved) { service.authorized_resolve.call(presented_type, {}, { current_user: current_user }) }
 
-    context "scalar types" do
-      shared_examples "checking permissions on the presented object" do
-        it "checks the abilities on the object being presented and returns the value" do
+    context 'scalar types' do
+      shared_examples 'checking permissions on the presented object' do
+        it 'checks the abilities on the object being presented and returns the value' do
           expected_permissions.each do |permission|
             spy_ability_check_for(permission, presented_object, passed: true)
           end
 
-          expect(resolved).to eq("Resolved value")
+          expect(resolved).to eq('Resolved value')
         end
 
         it "returns nil if the value wasn't authorized" do
@@ -45,61 +49,71 @@ describe Gitlab::Graphql::Authorize::AuthorizeFieldService do
         end
       end
 
-      context "when the field is a built-in scalar type" do
-        let(:field) { type_with_field(GraphQL::STRING_TYPE, :read_field).fields["testField"].to_graphql }
+      context 'when the field is a built-in scalar type' do
+        let(:field) { type_with_field(GraphQL::STRING_TYPE, :read_field).fields['testField'].to_graphql }
         let(:expected_permissions) { [:read_field] }
 
-        it_behaves_like "checking permissions on the presented object"
+        it_behaves_like 'checking permissions on the presented object'
       end
 
-      context "when the field is a list of scalar types" do
-        let(:field) { type_with_field([GraphQL::STRING_TYPE], :read_field).fields["testField"].to_graphql }
+      context 'when the field is a list of scalar types' do
+        let(:field) { type_with_field([GraphQL::STRING_TYPE], :read_field).fields['testField'].to_graphql }
         let(:expected_permissions) { [:read_field] }
 
-        it_behaves_like "checking permissions on the presented object"
+        it_behaves_like 'checking permissions on the presented object'
       end
 
-      context "when the field is sub-classed scalar type" do
-        let(:field) { type_with_field(Types::TimeType, :read_field).fields["testField"].to_graphql }
+      context 'when the field is sub-classed scalar type' do
+        let(:field) { type_with_field(Types::TimeType, :read_field).fields['testField'].to_graphql }
         let(:expected_permissions) { [:read_field] }
 
-        it_behaves_like "checking permissions on the presented object"
+        it_behaves_like 'checking permissions on the presented object'
       end
 
-      context "when the field is a list of sub-classed scalar types" do
-        let(:field) { type_with_field([Types::TimeType], :read_field).fields["testField"].to_graphql }
+      context 'when the field is a list of sub-classed scalar types' do
+        let(:field) { type_with_field([Types::TimeType], :read_field).fields['testField'].to_graphql }
         let(:expected_permissions) { [:read_field] }
 
-        it_behaves_like "checking permissions on the presented object"
+        it_behaves_like 'checking permissions on the presented object'
       end
     end
 
-    context "when the field is a specific type" do
+    context 'when the field is a specific type' do
       let(:custom_type) { type(:read_type) }
-      let(:object_in_field) { double("presented in field") }
-      let(:field) { type_with_field(custom_type, :read_field, object_in_field).fields["testField"].to_graphql }
+      let(:object_in_field) { double('presented in field') }
+      let(:field) { type_with_field(custom_type, :read_field, object_in_field).fields['testField'].to_graphql }
 
-      it "checks both field & type permissions" do
+      it 'checks both field & type permissions' do
         spy_ability_check_for(:read_field, object_in_field, passed: true)
         spy_ability_check_for(:read_type, object_in_field, passed: true)
 
         expect(resolved).to eq(object_in_field)
       end
 
-      it "returns nil if viewing was not allowed" do
+      it 'returns nil if viewing was not allowed' do
         spy_ability_check_for(:read_field, object_in_field, passed: false)
         spy_ability_check_for(:read_type, object_in_field, passed: true)
 
         expect(resolved).to be_nil
       end
 
-      context "when the field is a list" do
-        let(:object_1) { double("presented in field 1") }
-        let(:object_2) { double("presented in field 2") }
+      context 'when the field is not nullable' do
+        let(:field) { type_with_field(custom_type, [], object_in_field, null: false).fields['testField'].to_graphql }
+
+        it 'returns nil when viewing is not allowed' do
+          spy_ability_check_for(:read_type, object_in_field, passed: false)
+
+          expect(resolved).to be_nil
+        end
+      end
+
+      context 'when the field is a list' do
+        let(:object_1) { double('presented in field 1') }
+        let(:object_2) { double('presented in field 2') }
         let(:presented_types) { [double(object: object_1), double(object: object_2)] }
-        let(:field) { type_with_field([custom_type], :read_field, presented_types).fields["testField"].to_graphql }
+        let(:field) { type_with_field([custom_type], :read_field, presented_types).fields['testField'].to_graphql }
 
-        it "checks all permissions" do
+        it 'checks all permissions' do
           allow(Ability).to receive(:allowed?) { true }
 
           spy_ability_check_for(:read_field, object_1, passed: true)
@@ -110,7 +124,7 @@ describe Gitlab::Graphql::Authorize::AuthorizeFieldService do
           expect(resolved).to eq(presented_types)
         end
 
-        it "filters out objects that the user cannot see" do
+        it 'filters out objects that the user cannot see' do
           allow(Ability).to receive(:allowed?) { true }
 
           spy_ability_check_for(:read_type, object_1, passed: false)

spec/requests/api/graphql/project/repository_spec.rb

@@ -34,4 +34,28 @@ describe 'getting a repository in a project' do
       expect(graphql_data['project']).to be(nil)
     end
   end
+
+  context 'when the repository is only accessible to members' do
+    let(:project) do
+      create(:project, :public, :repository, repository_access_level: ProjectFeature::PRIVATE)
+    end
+
+    it 'returns a repository for the owner' do
+      post_graphql(query, current_user: current_user)
+
+      expect(graphql_data['project']['repository']).not_to be_nil
+    end
+
+    it 'returns nil for the repository for other users' do
+      post_graphql(query, current_user: create(:user))
+
+      expect(graphql_data['project']['repository']).to be_nil
+    end
+
+    it 'returns nil for the repository for other users' do
+      post_graphql(query, current_user: nil)
+
+      expect(graphql_data['project']['repository']).to be_nil
+    end
+  end
 end