Apparmor appears to not restrict read-access

Yes, same problem here.

The apparmor-profile allows reading the whole filesystem and has no exception for /home/
But the specification-page says: "AppArmor rules to completely hide /home"

An other question: Why does the apparmor-profile allows to execute programs from /media/** ?

I can confirm this bug. Running from a guest session I can access home folders of other users and the files in there.

I'm running Intrepid through kvm (virtmanager). I've installed from the beta desktop iso and updated the system. (gdm-guest-session 0.4)

I think the priority should be be at least "high". Here's why :

This bug makes it a security risk to let someone use a guest account on your computer.
Secondly if the text from http://www.ubuntu.com/testing/intrepid/beta#Guest%20session becomes the text for the final release Ubuntu looks bad :

[quote]
Guest session

The User Switcher panel applet (package fast-user-switch-applet) now provides an extra entry for starting a Guest session (by Martin Pitt). This creates a temporary password-less user account with restricted privileges: the account cannot access any users' home directories, nor permanently store data. This is sufficiently safe to lend your laptop to someone else for a quick email check.
[/quote]

Same problem here with Intrepid Beta. If I browse a user directory as guest with Nautilus, I can see the files and their previews which already reveal some of their content, but cannot open them with gedit "permission denied". In the console they can be opened.

I also think that for example /boot should be denied to the guest user, as he might be able to read out a plaintext password that is stored in /boot/grub/menu.lst to prevent access to root privileges during boot.

Guest-session should be completely jailed, in its temporary /home folder.
No access to anywhere.

Offtopic, where could I raise an feature request?
Somekind of /etc/gdm-guest.conf to be read when starting guest-session?
To pass different options.
Discussion http://ubuntuforums.org/showthread.php?t=936742

I can't figure out what is going on here. All of the guest users processes are bound by the Apparmor profile according to aa-status, but it still doesn't work.

Looks like a apparmor-bug!

I tried the same apparmor-profile with hardy. it forbids reading from /home/** there.

I think you're right. I've just created a minimal profile for gedit, just sufficient to get it to run, and I can still browse the entire filesystem

I reported this as #278619.

http://kernel.ubuntu.com/git?p=kees/ubuntu-intrepid.git;a=commitdiff;h=7d1b6a260c889fae9c8adbaeab19f30d2da320ab
https://lists.ubuntu.com/archives/kernel-team/2008-October/003227.html

The 2.6.27-6 kernel has fixed this problem.