From c9b4dc677abdebc02ecac4dca65a759d3f07b2a0 Mon Sep 17 00:00:00 2001
From: Patrick Derichs <pderichs@gitlab.com>
Date: Fri, 9 Aug 2019 14:54:57 +0200
Subject: [PATCH] Filter out old system notes for epics

---
 app/controllers/concerns/issuable_actions.rb                | 2 +-
 app/controllers/concerns/notes_actions.rb                   | 2 +-
 app/models/note.rb                                          | 4 ++++
 ...ity-epic-notes-api-reveals-historical-info-ce-master.yml | 5 +++++
 lib/api/discussions.rb                                      | 2 +-
 lib/api/helpers/notes_helpers.rb                            | 6 +++---
 lib/api/notes.rb                                            | 2 +-
 7 files changed, 16 insertions(+), 7 deletions(-)
 create mode 100644 changelogs/unreleased/security-epic-notes-api-reveals-historical-info-ce-master.yml

diff --git a/app/controllers/concerns/issuable_actions.rb b/app/controllers/concerns/issuable_actions.rb
index b86e4451a7e..1d6a1be402c 100644
--- a/app/controllers/concerns/issuable_actions.rb
+++ b/app/controllers/concerns/issuable_actions.rb
@@ -110,7 +110,7 @@ module IssuableActions
     end
 
     notes = prepare_notes_for_rendering(notes)
-    notes = notes.reject { |n| n.cross_reference_not_visible_for?(current_user) }
+    notes = notes.select { |n| n.visible_for?(current_user) }
 
     discussions = Discussion.build_collection(notes, issuable)
 
diff --git a/app/controllers/concerns/notes_actions.rb b/app/controllers/concerns/notes_actions.rb
index d2a961efff7..80be7095ed3 100644
--- a/app/controllers/concerns/notes_actions.rb
+++ b/app/controllers/concerns/notes_actions.rb
@@ -29,7 +29,7 @@ module NotesActions
     end
 
     notes = prepare_notes_for_rendering(notes)
-    notes = notes.reject { |n| n.cross_reference_not_visible_for?(current_user) }
+    notes = notes.select { |n| n.visible_for?(current_user) }
 
     notes_json[:notes] =
       if use_note_serializer?
diff --git a/app/models/note.rb b/app/models/note.rb
index a12d1eb7243..fae66ce7e4a 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -331,6 +331,10 @@ class Note < ApplicationRecord
     cross_reference? && !all_referenced_mentionables_allowed?(user)
   end
 
+  def visible_for?(user)
+    !cross_reference_not_visible_for?(user)
+  end
+
   def award_emoji?
     can_be_award_emoji? && contains_emoji_only?
   end
diff --git a/changelogs/unreleased/security-epic-notes-api-reveals-historical-info-ce-master.yml b/changelogs/unreleased/security-epic-notes-api-reveals-historical-info-ce-master.yml
new file mode 100644
index 00000000000..c639098721e
--- /dev/null
+++ b/changelogs/unreleased/security-epic-notes-api-reveals-historical-info-ce-master.yml
@@ -0,0 +1,5 @@
+---
+title: Filter out old system notes for epics in notes api endpoint response
+merge_request:
+author:
+type: security
diff --git a/lib/api/discussions.rb b/lib/api/discussions.rb
index 6c1acc3963f..9125207167c 100644
--- a/lib/api/discussions.rb
+++ b/lib/api/discussions.rb
@@ -239,7 +239,7 @@ module API
         # because notes are redacted if they point to projects that
         # cannot be accessed by the user.
         notes = prepare_notes_for_rendering(notes)
-        notes.reject { |n| n.cross_reference_not_visible_for?(current_user) }
+        notes.select { |n| n.visible_for?(current_user) }
       end
       # rubocop: enable CodeReuse/ActiveRecord
     end
diff --git a/lib/api/helpers/notes_helpers.rb b/lib/api/helpers/notes_helpers.rb
index b2bf6bf7417..f445834323d 100644
--- a/lib/api/helpers/notes_helpers.rb
+++ b/lib/api/helpers/notes_helpers.rb
@@ -12,7 +12,7 @@ module API
       end
 
       def update_note(noteable, note_id)
-        note = noteable.notes.find(params[:note_id])
+        note = noteable.notes.find(note_id)
 
         authorize! :admin_note, note
 
@@ -61,8 +61,8 @@ module API
       end
 
       def get_note(noteable, note_id)
-        note = noteable.notes.with_metadata.find(params[:note_id])
-        can_read_note = !note.cross_reference_not_visible_for?(current_user)
+        note = noteable.notes.with_metadata.find(note_id)
+        can_read_note = note.visible_for?(current_user)
 
         if can_read_note
           present note, with: Entities::Note
diff --git a/lib/api/notes.rb b/lib/api/notes.rb
index 84563d66ee8..16fca9acccb 100644
--- a/lib/api/notes.rb
+++ b/lib/api/notes.rb
@@ -42,7 +42,7 @@ module API
           # array returned, but this is really a edge-case.
           notes = paginate(raw_notes)
           notes = prepare_notes_for_rendering(notes)
-          notes = notes.reject { |n| n.cross_reference_not_visible_for?(current_user) }
+          notes = notes.select { |note| note.visible_for?(current_user) }
           present notes, with: Entities::Note
         end
         # rubocop: enable CodeReuse/ActiveRecord