Have "access management" plugin?

Hi, everyone:    I am now considering of the access function in my website app. For example, the normal user can only modify and destory his own comments, threads & uploaded attachments; user can choose hide his comment to public or show it outside. Of course, later on it will have some more access-restricted fucntion and path.    Does anyone have the experience in Rails about this?    Appreciate any of your reply!

Br MyST