Strongly-typed dataset security

Using a strongly typed dataset and its related table Adapters, normally when I want the changes to pass back, just pass it the table and let it do all the work.

What are some easy ways to enforce security roles on the application user as to which fields they can insert/update/delete when the database is using an application ID instead of user level security?

Do I have to go row by row and check each row against what this particular user is allowed to do (by checking the current version of every field against it's proposed version against their role's permissions?

I believe the first level of security would be locking down the columns on the UI a particular user is not supposed to modify, but what about at the data level? Is there a nice way to do this?

Is this easier in linq-to-sql?

I can read/function in VB and C# so code/examples in either is fine.