Redact unsubscribe links in issuable texts

It's possible that user pastes accidentally also unsubscribe link
which is included in footer of notification emails. This unsubscribe
link contains personal token which attacker then use to act as the
original user (e.g. for sending comments under his/her identity).

1 files changed, 62 insertions, 0 deletions

diff --git a/lib/gitlab/background_migration/redact_links.rb b/lib/gitlab/background_migration/redact_links.rb
new file mode 100644
index 00000000000..f5d3bcdd517
--- /dev/null
+++ b/lib/gitlab/background_migration/redact_links.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+# rubocop:disable Style/Documentation
+
+module Gitlab
+  module BackgroundMigration
+    class RedactLinks
+      module Redactable
+        extend ActiveSupport::Concern
+
+        def redact_field!(field)
+          self[field].gsub!(%r{/sent_notifications/\h{32}/unsubscribe}, '/sent_notifications/REDACTED/unsubscribe')
+
+          if self.changed?
+            self.update_columns(field => self[field],
+                                "#{field}_html" => nil)
+          end
+        end
+      end
+
+      class Note < ActiveRecord::Base
+        include EachBatch
+        include Redactable
+
+        self.table_name = 'notes'
+        self.inheritance_column = :_type_disabled
+      end
+
+      class Issue < ActiveRecord::Base
+        include EachBatch
+        include Redactable
+
+        self.table_name = 'issues'
+        self.inheritance_column = :_type_disabled
+      end
+
+      class MergeRequest < ActiveRecord::Base
+        include EachBatch
+        include Redactable
+
+        self.table_name = 'merge_requests'
+        self.inheritance_column = :_type_disabled
+      end
+
+      class Snippet < ActiveRecord::Base
+        include EachBatch
+        include Redactable
+
+        self.table_name = 'snippets'
+        self.inheritance_column = :_type_disabled
+      end
+
+      def perform(model_name, field, start_id, stop_id)
+        link_pattern = "%/sent_notifications/" + ("_" * 32) + "/unsubscribe%"
+        model = "Gitlab::BackgroundMigration::RedactLinks::#{model_name}".constantize
+
+        model.where("#{field} like ?", link_pattern).where(id: start_id..stop_id).each do |resource|
+          resource.redact_field!(field)
+        end
+      end
+    end
+  end
+end