Hide events from internal projects in public feed for anonymous users

This change fixes a bug where an anonymous user was able to see the
activity related to internal projects when visiting the public profile
of a user of the GitLab instance.

app/finders/user_recent_events_finder.rb

@@ -56,7 +56,7 @@ class UserRecentEventsFinder
 
     visible = target_user
       .project_interactions
-      .where(visibility_level: [Gitlab::VisibilityLevel::INTERNAL, Gitlab::VisibilityLevel::PUBLIC])
+      .where(visibility_level: Gitlab::VisibilityLevel.levels_for_user(current_user))
       .select(:id)
 
     Gitlab::SQL::Union.new([authorized, visible]).to_sql

changelogs/unreleased/security-rd-do-not-show-internal-info-in-public-feed.yml

+---
+title: Don't show events from internal projects for anonymous users in public feed
+merge_request:
+author:
+type: security

spec/finders/user_recent_events_finder_spec.rb

 require 'spec_helper'
 
 describe UserRecentEventsFinder do
-  let(:user) { create(:user) }
-  let(:project) { create(:project) }
-  let(:project_owner) { project.creator }
-  let!(:event) { create(:event, project: project, author: project_owner) }
+  let(:current_user)     { create(:user) }
+  let(:project_owner)    { create(:user) }
+  let(:private_project)  { create(:project, :private, creator: project_owner) }
+  let(:internal_project) { create(:project, :internal, creator: project_owner) }
+  let(:public_project)   { create(:project, :public, creator: project_owner) }
+  let!(:private_event)   { create(:event, project: private_project, author: project_owner) }
+  let!(:internal_event)  { create(:event, project: internal_project, author: project_owner) }
+  let!(:public_event)    { create(:event, project: public_project, author: project_owner) }
 
-  subject(:finder) { described_class.new(user, project_owner) }
+  subject(:finder) { described_class.new(current_user, project_owner) }
 
   describe '#execute' do
-    it 'does not include the event when a user does not have access to the project' do
-      expect(finder.execute).to be_empty
+    context 'current user does not have access to projects' do
+      it 'returns public and internal events' do
+        records = finder.execute
+
+        expect(records).to include(public_event, internal_event)
+        expect(records).not_to include(private_event)
+      end
     end
 
-    context 'when the user has access to a project' do
+    context 'when current user has access to the projects' do
       before do
-        project.add_developer(user)
+        private_project.add_developer(current_user)
+        internal_project.add_developer(current_user)
+        public_project.add_developer(current_user)
       end
 
-      it 'includes the event' do
-        expect(finder.execute).to include(event)
+      it 'returns all the events' do
+        expect(finder.execute).to include(private_event, internal_event, public_event)
       end
 
-      it 'does not include the event if the user cannot read cross project' do
-        expect(Ability).to receive(:allowed?).with(user, :read_cross_project) { false }
+      it 'does not include the events if the user cannot read cross project' do
+        expect(Ability).to receive(:allowed?).with(current_user, :read_cross_project) { false }
         expect(finder.execute).to be_empty
       end
     end
+
+    context 'when current user is anonymous' do
+      let(:current_user) { nil }
+
+      it 'returns public events only' do
+        expect(finder.execute).to eq([public_event])
+      end
+    end
   end
 end