To expand on this...
CR does not have a DB client installed, we assume the Client has been installed and configured and is working. So if any Client software can connect then CR should be able to also.
The user logging to run reports requires permission on Owner/read/write because the users will need to create temp tables to store the data server side. CR does NOT require permission to create Temp tables, just the user.
CR fully supports DB security, if the user does not have rights to access a database/table then that user will not be able to run the report, or create it off those tables.
Often Report Designers will create a "CR User" and add that user account to the DB Server.
Another way is to use Trusted Authentication ( option in the DB Wizard ). Security is all managed by the DBA.
Don
PS - Technically CR does not require write permissions but some people do create Commands that write data and other things in which case the user needs permissions to do this.
If you look at Profilers you will see it's CR Designer accessing the Database.