38.1. Is a Set-User-ID or Set-Group-ID Program Required?

One of the best pieces of advice concerning set-user-ID and set-group-ID programs is to avoid writing them whenever possible. If there is an alternative way of performing a task that doesn’t involve giving a program privilege, we should generally employ that alternative, since it eliminates the possibility of a security compromise.

Sometimes, we can isolate the functionality that needs privilege into a separate program that performs a single task, and exec that program in a child process as required. This technique can be especially useful for libraries. One example of such a use is provided by the pt_chown program described in Section 64.2.2.