When you use OmniAuth to login to a web app through Facebook, these are the permissions the webapp has:
Access my basic information Includes name, profile pictu
You can check on option using the :scope
attribute:
use OmniAuth::Strategies::Facebook, 'app_id', 'app_secret', {:scope => 'email,offline_access, your,scope,you,want'}
Check the Facebook permissions documentation what scope you really want and define it separate by a commant on :scope
option.
If you use an initializer to define your OamniOauth, it's like that:
Rails.application.config.middleware.use OmniAuth::Builder do
provider :facebook, 'APP_ID', 'APP_SECRET', {:scope => 'email,offline_access, your,scope,you,want'}
end