linuxexpert-practice-labs/labs/rhcsa/6-5-permission-problems/README.md

RHCSA 6.5: Fixing file permission problems

A shared group directory, a file one user can't reach, and what chmod does to an ACL's mask.

Before you start

The lab creates group devs with members alice and bob, and a third user, carol, who isn't in it (password Lab-Pass-1 for all three). It also creates the directory /srv/reports (mode 750, owned by root) with an ACL entry that gives bob read and execute access.

Tasks

1. Make a directory /srv/devs where every new file belongs to group devs and is writable by its members, and members can't delete each other's files.
2. As root, create /srv/secret/f.txt (mode 644) in a directory /srv/secret with mode 700. Find out why bob can't read it, then let only bob read it, without giving access to anyone else.
3. Run chmod 700 /srv/reports and look at bob's ACL entry with getfacl. Write the effective permissions it shows to /root/lab-answers/3, then give bob his access back with setfacl -m m::rx.

Hints

• chgrp, chmod 3770 (or g+s,o+t), setfacl -d -m g:devs:rw; ls -ld, getfacl. Test as the users: su - alice, sudo -u bob.
• namei -l /srv/secret/f.txt; setfacl -m u:bob:x on the directory.
• getfacl -c /srv/reports shows #effective: next to masked entries.