Chapter Nine Question Two

Linux Programming Interface Michael Kerrisk

Question

Is a process with the following user IDs privileged? Explain your answer. real=0 effective=1000 saved=1000 file-system=1000

Answer

The real ID is 0 meaning that the program initially was owned by a privileged user. However, the effective, saved and file-system IDs could have been changed by setreuid() system call. This process wouldn't be a privileged process any longer. However, it could use many of the system calls mentioned in Chapter Nine Question One to regain a 0 effective user and regain those privileges.