How to secure Data sources in browser ???

[QPun]

Hi all, I got a security problem here, let's say I got a SQL Report Server, with browser URL : //rptserver/reports I have datasource1 as datasource I also have provide a model (RptModel1) that created from datasource1 using Visual Studio I want to enable users to use Report Builder , using available model(RptModel1) but restrict them from regenerate model from datasource1. So, how to secure that datasource? I need your help,Please... Thanks in advance

[QPun]

Is there something wrong in my question so no one understand it? Or maybe there's no solution for my problem? :->