In Unix, every process has a real user id (ruid), an effective user id (euid), and a saved user id (suid). Processes with an euid of 0 have special root privileges. a. If a process with user id n forks to create another process, what user id does the new process have? (Hint: it's the same answer for euid, ruid, and suid.) b. If a process with euid n makes a setuid system call, what possible euids can the process run with after the call, in each of the following situations: a. Before: euid = n> 0, saved user id suid=m and real user id ruid = m. After:? b. Before: n=0 After:? c. In qmail, most modules run under separate user ids. Similarly, each Android application runs in a separate process using a separate user id. From a security standpoint, what is the advantage of assigning separate uids instead of using the same uid for all? Explain. d. Why should the separate uids be non-zero?

In Unix, every process has a real user id (ruid), an effective user id (euid), and a saved user id (suid). Processes with an euid of 0 have special root privileges. a. If a process with user id n forks to create another process, what user id does the new process have? (Hint: it's the same answer for euid, ruid, and suid.) b. If a process with euid n makes a setuid system call, what possible euids can the process run with after the call, in each of the following situations: a. Before: euid = n> 0, saved user id suid=m and real user id ruid = m. After:? b. Before: n=0 After:? c. In qmail, most modules run under separate user ids. Similarly, each Android application runs in a separate process using a separate user id. From a security standpoint, what is the advantage of assigning separate uids instead of using the same uid for all? Explain. d. Why should the separate uids be non-zero?

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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