linuxexpert-practice-labs/labs/linux-plus/5-4-1-access-issues/README.md

Linux+ 5.4.1: Permission, SELinux and account problems

A directory that blocks the way, an ACL mask, an attribute that stops root, and an account that can't log in.

Before you start

The lab creates user permtest (password Lab-Pass-1) and the files /srv/lab/inner/f.txt and /srv/lab/inner/old-report.txt. It installs the acl tools if they're missing. Several things stand in permtest's way. Write answers to the files in /root/lab-answers/.

Tasks

1. permtest can't read /srv/lab/inner/f.txt, although the file itself is readable by everyone. Find the path component that blocks it, write it to /root/lab-answers/1, and fix it so others can pass through, without giving them write access.
2. f.txt has an ACL entry giving permtest read and write access, but permtest still can't write to it. Find the ACL entry that limits it, write its name to /root/lab-answers/2, and fix it without removing permtest's entry.
3. Even root can't delete /srv/lab/inner/old-report.txt. Find out why, write the attribute's name to /root/lab-answers/3, and delete the file.
4. permtest can't log in at all. Find the two causes (su - permtest and chage -l permtest help) and fix them, so that permtest gets a bash shell again and its account never expires.

Hints

• namei -l PATH, chmod.
• getfacl; the mask entry; setfacl -m m::rw.
• lsattr, chattr -i.
• getent passwd permtest, usermod -s /bin/bash, chage -l, chage -E -1.