Prevent claiming associated model IDs via import and added relevant specs

lib/gitlab/import_export/attribute_cleaner.rb

+module Gitlab
+  module ImportExport
+    class AttributeCleaner
+      IGNORED_REFERENCES = Gitlab::ImportExport::RelationFactory::PROJECT_REFERENCES + Gitlab::ImportExport::RelationFactory::USER_REFERENCES
+
+      def self.clean!(relation_hash:)
+        relation_hash.select! do |key, _value|
+          IGNORED_REFERENCES.include?(key) || !key.end_with?('_id')
+        end
+      end
+    end
+  end
+end

lib/gitlab/import_export/project_tree_restorer.rb

@@ -104,9 +104,10 @@ module Gitlab
       def create_relation(relation, relation_hash_list)
         relation_array = [relation_hash_list].flatten.map do |relation_hash|
           Gitlab::ImportExport::RelationFactory.create(relation_sym: relation.to_sym,
-                                                       relation_hash: relation_hash.merge('project_id' => restored_project.id),
+                                                       relation_hash: relation_hash,
                                                        members_mapper: members_mapper,
-                                                       user: @user)
+                                                       user: @user,
+                                                       project_id: restored_project.id)
         end
         relation_hash_list.is_a?(Array) ? relation_array : relation_array.first

lib/gitlab/import_export/relation_factory.rb

@@ -13,6 +13,8 @@ module Gitlab
       USER_REFERENCES = %w[author_id assignee_id updated_by_id user_id].freeze
+      PROJECT_REFERENCES = %w[project_id source_project_id gl_project_id target_project_id].freeze
+
       BUILD_MODELS = %w[Ci::Build commit_status].freeze
       IMPORTED_OBJECT_MAX_RETRIES = 5.freeze
@@ -25,9 +27,9 @@ module Gitlab
         new(*args).create
       end
-      def initialize(relation_sym:, relation_hash:, members_mapper:, user:)
+      def initialize(relation_sym:, relation_hash:, members_mapper:, user:, project_id:)
         @relation_name = OVERRIDES[relation_sym] || relation_sym
-        @relation_hash = relation_hash.except('id', 'noteable_id')
+        @relation_hash = relation_hash.except('id', 'noteable_id').merge('project_id' => project_id)
         @members_mapper = members_mapper
         @user = user
         @imported_object_retries = 0
@@ -153,7 +155,11 @@ module Gitlab
       end
       def parsed_relation_hash
-        @parsed_relation_hash ||= @relation_hash.reject { |k, _v| !relation_class.attribute_method?(k) }
+        @parsed_relation_hash ||= begin
+          Gitlab::ImportExport::AttributeCleaner.clean!(relation_hash: @relation_hash)
+
+          @relation_hash.reject { |k, _v| !relation_class.attribute_method?(k) }
+        end
       end
       def set_st_diffs

spec/lib/gitlab/import_export/attribute_cleaner_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ImportExport::AttributeCleaner, lib: true do
+  let(:unsafe_hash) do
+    {
+      'service_id' => 99,
+      'moved_to_id' => 99,
+      'namespace_id' => 99,
+      'ci_id' => 99,
+      'random_project_id' => 99,
+      'random_id' => 99,
+      'milestone_id' => 99,
+      'project_id' => 99,
+      'user_id' => 99,
+      'random_id_in_the_middle' => 99,
+      'notid' => 99
+    }
+  end
+
+  let(:post_safe_hash) do
+    {
+      'project_id' => 99,
+      'user_id' => 99,
+      'random_id_in_the_middle' => 99,
+      'notid' => 99
+    }
+  end
+
+  it 'removes unwanted attributes from the hash' do
+    described_class.clean!(relation_hash: unsafe_hash)
+
+    expect(unsafe_hash).to eq(post_safe_hash)
+  end
+end

spec/lib/gitlab/import_export/relation_factory_spec.rb

+require 'spec_helper'
+
+describe Gitlab::ImportExport::RelationFactory, lib: true do
+  let(:project) { create(:empty_project) }
+  let(:members_mapper) { double('members_mapper').as_null_object }
+  let(:user) { create(:user) }
+  let(:created_object) do
+    described_class.create(relation_sym: relation_sym,
+                           relation_hash: relation_hash,
+                           members_mapper: members_mapper,
+                           user: user,
+                           project_id: project.id)
+  end
+
+  context 'hook object' do
+    let(:relation_sym) { :hooks }
+    let(:id) { 999 }
+    let(:service_id) { 99 }
+    let(:original_project_id) { 8 }
+    let(:token) { 'secret' }
+
+    let(:relation_hash) do
+      {
+        'id' => id,
+        'url' => 'https://example.json',
+        'project_id' => original_project_id,
+        'created_at' => '2016-08-12T09:41:03.462Z',
+        'updated_at' => '2016-08-12T09:41:03.462Z',
+        'service_id' => service_id,
+        'push_events' => true,
+        'issues_events' => false,
+        'merge_requests_events' => true,
+        'tag_push_events' => false,
+        'note_events' => true,
+        'enable_ssl_verification' => true,
+        'build_events' => false,
+        'wiki_page_events' => true,
+        'token' => token
+      }
+    end
+
+    it 'does not have the original ID' do
+      expect(created_object.id).not_to eq(id)
+    end
+
+    it 'does not have the original service_id' do
+      expect(created_object.service_id).not_to eq(service_id)
+    end
+
+    it 'does not have the original project_id' do
+      expect(created_object.project_id).not_to eq(original_project_id)
+    end
+
+    it 'has the new project_id' do
+      expect(created_object.project_id).to eq(project.id)
+    end
+
+    it 'has a token' do
+      expect(created_object.token).to eq(token)
+    end
+
+    context 'original service exists' do
+      let(:service_id) { Service.create(project: project).id }
+
+      it 'does not have the original service_id' do
+        expect(created_object.service_id).not_to eq(service_id)
+      end
+    end
+  end
+
+  # Mocks an ActiveRecordish object with the dodgy columns
+  class FooModel
+    include ActiveModel::Model
+
+    def initialize(params)
+      params.each { |key, value| send("#{key}=", value) }
+    end
+
+    def values
+      instance_variables.map { |ivar| instance_variable_get(ivar) }
+    end
+  end
+
+  # `project_id`, `described_class.USER_REFERENCES`, noteable_id, target_id, and some project IDs are already
+  # re-assigned by described_class.
+  context 'Potentially hazardous foreign keys' do
+    let(:relation_sym) { :hazardous_foo_model }
+    let(:relation_hash) do
+      {
+        'service_id' => 99,
+        'moved_to_id' => 99,
+        'namespace_id' => 99,
+        'ci_id' => 99,
+        'random_project_id' => 99,
+        'random_id' => 99,
+        'milestone_id' => 99,
+        'project_id' => 99,
+        'user_id' => 99,
+      }
+    end
+
+    class HazardousFooModel < FooModel
+      attr_accessor :service_id, :moved_to_id, :namespace_id, :ci_id, :random_project_id, :random_id, :milestone_id, :project_id
+    end
+
+    it 'does not preserve any foreign key IDs' do
+      expect(created_object.values).not_to include(99)
+    end
+  end
+
+  context 'Project references' do
+    let(:relation_sym) { :project_foo_model }
+    let(:relation_hash) do
+      Gitlab::ImportExport::RelationFactory::PROJECT_REFERENCES.map { |ref| { ref => 99 } }.inject(:merge)
+    end
+
+    class ProjectFooModel < FooModel
+      attr_accessor(*Gitlab::ImportExport::RelationFactory::PROJECT_REFERENCES)
+    end
+
+    it 'does not preserve any project foreign key IDs' do
+      expect(created_object.values).not_to include(99)
+    end
+  end
+end