Filter not accessible label events

Label events may use cross-project or cross-group references,
if the projects are not accessible by user, we don't show these
label events.

3 files changed, 65 insertions, 0 deletions

diff --git a/app/finders/resource_label_event_finder.rb b/app/finders/resource_label_event_finder.rb
new file mode 100644
index 00000000000..9aafd6e91b9
--- /dev/null
+++ b/app/finders/resource_label_event_finder.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+class ResourceLabelEventFinder
+  include FinderMethods
+
+  MAX_PER_PAGE = 100
+
+  attr_reader :params, :current_user, :eventable
+
+  def initialize(current_user, eventable, params = {})
+    @current_user = current_user
+    @eventable = eventable
+    @params = params
+  end
+
+  def execute
+    events = eventable.resource_label_events.inc_relations
+    events = events.page(page).per(per_page)
+    events = visible_to_user(events)
+
+    Kaminari.paginate_array(events)
+  end
+
+  private
+
+  def visible_to_user(events)
+    ResourceLabelEvent.preload_label_subjects(events)
+
+    events.select do |event|
+      Ability.allowed?(current_user, :read_label, event)
+    end
+  end
+
+  def per_page
+    [params[:per_page], MAX_PER_PAGE].compact.min
+  end
+
+  def page
+    params[:page] || 1
+  end
+end
diff --git a/app/models/resource_label_event.rb b/app/models/resource_label_event.rb
index 93d0a37d186..98fc9e7bae8 100644
--- a/app/models/resource_label_event.rb
+++ b/app/models/resource_label_event.rb
@@ -13,6 +13,7 @@ class ResourceLabelEvent < ApplicationRecord
   belongs_to :label
 
   scope :created_after, ->(time) { where('created_at > ?', time) }
+  scope :inc_relations, -> { includes(:label, :user) }
 
   validates :user, presence: { unless: :importing? }, on: :create
   validates :label, presence: { unless: :importing? }, on: :create
@@ -30,6 +31,15 @@ class ResourceLabelEvent < ApplicationRecord
     %i(issue merge_request).freeze
   end
 
+  def self.preload_label_subjects(events)
+    labels = events.map(&:label).compact
+    project_labels, group_labels = labels.partition { |label| label.is_a? ProjectLabel }
+
+    preloader = ActiveRecord::Associations::Preloader.new
+    preloader.preload(project_labels, { project: :project_feature })
+    preloader.preload(group_labels, :group)
+  end
+
   def issuable
     issue || merge_request
   end
diff --git a/app/policies/resource_label_event_policy.rb b/app/policies/resource_label_event_policy.rb
new file mode 100644
index 00000000000..de4748d9890
--- /dev/null
+++ b/app/policies/resource_label_event_policy.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class ResourceLabelEventPolicy < BasePolicy
+  condition(:can_read_label) { @subject.label_id.nil? || can?(:read_label, @subject.label) }
+  condition(:can_read_issuable) { can?(:"read_#{@subject.issuable.to_ability_name}", @subject.issuable) }
+
+  rule { can_read_label }.policy do
+    enable :read_label
+  end
+
+  rule { can_read_label & can_read_issuable }.policy do
+    enable :read_resource_label_event
+  end
+end