config.routing.yml

config_admin_import_form_submit in drupal/core/modules/config/config.admin.inc

Form submission handler for config_admin_import_form().

config_menu in drupal/core/modules/config/config.module

Implements hook_menu().

config_diff:
  pattern: '/admin/config/development/sync/diff/{config_file}'
  defaults:
    _content: '\Drupal\config\Controller\ConfigController::diff'
  requirements:
    _permission: 'synchronize configuration'
config_export_download:
  pattern: '/admin/config/development/export-download'
  defaults:
    _controller: '\Drupal\config\Controller\ConfigController::downloadExport'
  requirements:
    _permission: 'export configuration'
config_export:
  pattern: '/admin/config/development/export'
  defaults:
    _form: '\Drupal\config\Form\ConfigExportForm'
  requirements:
    _permission: 'export configuration'
config_import:
  pattern: '/admin/config/development/import'
  defaults:
    _form: '\Drupal\config\Form\ConfigImportForm'
  requirements:
    _permission: 'import configuration'