nopasswdlogin does not play will with mdm defaults

[sam tygier]

I want to enable passwordless login on a multiuser system. I.e. the users just need to click their name to log in.
Various places only explain that you need to add users to the nopasswdlogin group (I think this is what the tickbox in the users control panel does).

/etc/pam.d/mdm already has the required line to then allow passwordless log in (auth sufficient pam_succeed_if.so user ingroup nopasswdlogin).

However by default in the mdm configuration the 'Automatically select the last logged in user' is ticked. This selection is now enough to log that user in.

Steps to reproduce:
1) create several user accounts
2) add users to the nopasswdlogin group (adduser username1 nopasswdlogin) (you may need to create this group)
2alt) tick the "Don't ask for password at login" option in the users control panel
3) Log in as one of the nopasswdlogin users
4) Log out
5) you will now be automatically logged back in as that user, with no chance to select another user.

work around:
In Login window perfernces -> Options untick ''Automatically select the last logged in user'

[Tamas Bekasi (froggy)]

I observed this at a fresh install of Mint 16, but I have not added any users to the nopasswdlogin group. I simply did not set a password to any of the newly created users, and still got this unavoidable autologin effect as long as the "automatically select last logged in user" option is enabled.

[Daniel Ellis (danellisuk)]

Testing with Linux Mint 17, the problem also affects selection when using the keyboard arrow keys. Simply highlighting a user will cause the user to login, whereas you would expect to have to press enter.