Right now the only to ask for permissions in React Native on Android M is to hack into the MainActivity java code (see https://github.com/Tiagojdferreira/rn-geolocation/issues/1 for an example). There should probably be a way to ask for the permissions from javascript in core RN.

The Cordova team has added a way to do this that may be interesting to look at: http://cordova.apache.org/docs/en/latest/guide/platforms/android/plugin.html