Merge branch '18033-private-repo-mentions' into 'master'

Ensure logged-out users can't see private refs

https://gitlab.com/gitlab-org/gitlab-ce/issues/18033

I'm still not sure what to do about the CHANGELOG on security issues - should I add to a patch release? This issue was assigned to 8.10.

See merge request !1974
(cherry picked from commit 3a6ebb1f)

CHANGELOG

@@ -2,6 +2,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.7.9
   - Fix privilege escalation issue with OAuth external users.
+  - Ensure references to private repos aren't shown to logged-out users.
 
 v 8.7.8
   - Fix visibility of snippets when searching.

app/services/todo_service.rb

@@ -170,7 +170,7 @@ class TodoService
   end
 
   def filter_mentioned_users(project, target, author)
-    mentioned_users = target.mentioned_users
+    mentioned_users = target.mentioned_users(author)
     mentioned_users = reject_users_without_access(mentioned_users, project, target)
     mentioned_users.delete(author)
     mentioned_users.uniq

spec/models/concerns/mentionable_spec.rb

@@ -29,6 +29,43 @@ describe Issue, "Mentionable" do
     it { is_expected.not_to include(user2) }
   end
 
+  describe '#referenced_mentionables' do
+    context 'with an issue on a private project' do
+      let(:project) { create(:empty_project, :public) }
+      let(:issue) { create(:issue, project: project) }
+      let(:public_issue) { create(:issue, project: project) }
+      let(:private_project) { create(:empty_project, :private) }
+      let(:private_issue) { create(:issue, project: private_project) }
+      let(:user) { create(:user) }
+
+      def referenced_issues(current_user)
+        text = "#{private_issue.to_reference(project)} and #{public_issue.to_reference}"
+
+        issue.referenced_mentionables(current_user, text)
+      end
+
+      context 'when the current user can see the issue' do
+        before { private_project.team << [user, Gitlab::Access::DEVELOPER] }
+
+        it 'includes the reference' do
+          expect(referenced_issues(user)).to contain_exactly(private_issue, public_issue)
+        end
+      end
+
+      context 'when the current user cannot see the issue' do
+        it 'does not include the reference' do
+          expect(referenced_issues(user)).to contain_exactly(public_issue)
+        end
+      end
+
+      context 'when there is no current user' do
+        it 'does not include the reference' do
+          expect(referenced_issues(nil)).to contain_exactly(public_issue)
+        end
+      end
+    end
+  end
+
   describe '#create_cross_references!' do
     let(:project) { create(:project) }
     let(:author)  { double('author') }