Binary package hint: gksu
sudo and gksudo don't work in guest sessions on Lucid. By "guest session" I mean in particular the temporary session created and disposed of on the fly by selecting "Guest session" from the session menu.
First, SUDO
Running sudo from a command prompt within a guest session produces the message:
sudo: Unable to change to sudoers gid: Operation not permitted
My understanding is that this is a result of SELinux configuration. This, then, could be understood as security-based design decision, rather than a bug. I am using the default SELinux configuration.
Now, GKSUDO
Running a program through gksudo (such as synaptic or most program on the System|Administration menu) results in a pause of a few seconds, while the system wait cursor spins, followed by nothing. No error message is returned, no visible program is run. I expect that I will be prompted for a password or notified that I don't have permission to execute this command, but that isn't what happens. This is definitely a bug, as the user should be given some kind of feedback on his action.
This is probably not the right package to report this bug in. It seems to be more of an overall security configuration issue. Please provide suggestions if you think this bug should be sent elsewhere. Nevertheless, I filed it in this package because I think the most immediate way to fix this bug is to have gksu give a meaningful error message if it is unable to run sudo.
The 'guest' user created by gdm-guest-session is a passwordless system user by design, and gksu fails when trying to prompt for a password. One way to make the error dialog appear might be that gksu checks whether the GDMSESSION environment variable equals 'guest-restricted', and skips the password prompting attempt if it does.