Require maintainer permission to transfer projects

app/policies/group_policy.rb

@@ -131,6 +131,8 @@ class GroupPolicy < BasePolicy
 
   rule { owner | admin }.enable :read_statistics
 
+  rule { maintainer & can?(:create_projects) }.enable :transfer_projects
+
   def access_level
     return GroupMember::NO_ACCESS if @user.nil?
 

app/policies/namespace_policy.rb

@@ -15,6 +15,8 @@ class NamespacePolicy < BasePolicy
   end
 
   rule { personal_project & ~can_create_personal_project }.prevent :create_projects
+
+  rule { (owner | admin) & can?(:create_projects) }.enable :transfer_projects
 end
 
 NamespacePolicy.prepend_if_ee('EE::NamespacePolicy')

app/services/projects/transfer_service.rb

@@ -98,7 +98,7 @@ module Projects
       @new_namespace &&
         can?(current_user, :change_namespace, project) &&
         @new_namespace.id != project.namespace_id &&
-        current_user.can?(:create_projects, @new_namespace)
+        current_user.can?(:transfer_projects, @new_namespace)
     end
 
     def update_namespace_and_visibility(to_namespace)

changelogs/unreleased/security-developer-transfer-project.yml

+---
+title: Require Maintainer permission on group where project is transferred to
+merge_request:
+author:
+type: security

spec/policies/group_policy_spec.rb

@@ -354,6 +354,88 @@ describe GroupPolicy do
     end
   end
 
+  context 'transfer_projects' do
+    shared_examples_for 'allowed to transfer projects' do
+      before do
+        group.update(project_creation_level: project_creation_level)
+      end
+
+      it { is_expected.to be_allowed(:transfer_projects) }
+    end
+
+    shared_examples_for 'not allowed to transfer projects' do
+      before do
+        group.update(project_creation_level: project_creation_level)
+      end
+
+      it { is_expected.to be_disallowed(:transfer_projects) }
+    end
+
+    context 'reporter' do
+      let(:current_user) { reporter }
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::NO_ONE_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::MAINTAINER_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::DEVELOPER_MAINTAINER_PROJECT_ACCESS }
+      end
+    end
+
+    context 'developer' do
+      let(:current_user) { developer }
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::NO_ONE_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::MAINTAINER_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::DEVELOPER_MAINTAINER_PROJECT_ACCESS }
+      end
+    end
+
+    context 'maintainer' do
+      let(:current_user) { maintainer }
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::NO_ONE_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::MAINTAINER_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::DEVELOPER_MAINTAINER_PROJECT_ACCESS }
+      end
+    end
+
+    context 'owner' do
+      let(:current_user) { owner }
+
+      it_behaves_like 'not allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::NO_ONE_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::MAINTAINER_PROJECT_ACCESS }
+      end
+
+      it_behaves_like 'allowed to transfer projects' do
+        let(:project_creation_level) { ::Gitlab::Access::DEVELOPER_MAINTAINER_PROJECT_ACCESS }
+      end
+    end
+  end
+
   context "create_projects" do
     context 'when group has no project creation level set' do
       before_all do

spec/policies/namespace_policy_spec.rb

@@ -6,7 +6,7 @@ describe NamespacePolicy do
   let(:admin) { create(:admin) }
   let(:namespace) { create(:namespace, owner: owner) }
 
-  let(:owner_permissions) { [:create_projects, :admin_namespace, :read_namespace, :read_statistics] }
+  let(:owner_permissions) { [:create_projects, :admin_namespace, :read_namespace, :read_statistics, :transfer_projects] }
 
   subject { described_class.new(current_user, namespace) }
 
@@ -31,6 +31,7 @@ describe NamespacePolicy do
       let(:owner) { create(:user, projects_limit: 0) }
 
       it { is_expected.to be_disallowed(:create_projects) }
+      it { is_expected.to be_disallowed(:transfer_projects) }
     end
   end
 

spec/requests/api/projects_spec.rb

@@ -2648,6 +2648,22 @@ describe API::Projects do
         expect(response).to have_gitlab_http_status(400)
       end
     end
+
+    context 'when authenticated as developer' do
+      before do
+        group.add_developer(user)
+      end
+
+      context 'target namespace allows developers to create projects' do
+        let(:group) { create(:group, project_creation_level: ::Gitlab::Access::DEVELOPER_MAINTAINER_PROJECT_ACCESS) }
+
+        it 'fails transferring the project to the target namespace' do
+          put api("/projects/#{project.id}/transfer", user), params: { namespace: group.id }
+
+          expect(response).to have_gitlab_http_status(400)
+        end
+      end
+    end
   end
 
   it_behaves_like 'custom attributes endpoints', 'projects' do

spec/services/projects/transfer_service_spec.rb

@@ -222,6 +222,24 @@ describe Projects::TransferService do
     it { expect(project.errors[:new_namespace]).to include('Project with same name or path in target namespace already exists') }
   end
 
+  context 'target namespace allows developers to create projects' do
+    let(:group) { create(:group, project_creation_level: ::Gitlab::Access::DEVELOPER_MAINTAINER_PROJECT_ACCESS) }
+
+    context 'the user is a member of the target namespace with developer permissions' do
+      subject(:transfer_project_result) { transfer_project(project, user, group) }
+
+      before do
+        group.add_developer(user)
+      end
+
+      it 'does not allow project transfer to the target namespace' do
+        expect(transfer_project_result).to eq false
+        expect(project.namespace).to eq(user.namespace)
+        expect(project.errors[:new_namespace]).to include('Transfer failed, please contact an admin.')
+      end
+    end
+  end
+
   def transfer_project(project, user, new_namespace)
     service = Projects::TransferService.new(project, user)