password-free ubuntu login with facebrowser

If you trust everyone who has physical access to a pc (if not then you are encrypting your files, right?) then there seems little point in having to type a password just because more than one user uses the pc.

So here's how to log in from the gdm "face browser" with a single click.
Instructions tested with Ubuntu 8.04 Hardy Heron and 8.10 Intrepid Ibex.


as root, create a new file containing the usernames of all the users you want be able to log in through gdm without entering a password:

sudo -i
echo 'username' >> /etc/gdm/nopassusers

now still as root modify the pam settings for gdm to check this file and allow this user in based on being in the list:
vi  /etc/pam.d/gdm

vi /etc/pam.d/gdm

and modify to contain the new listfile item

#%PAM-1.0
auth requisite pam_nologin.so
auth required pam_env.so readenv=1
auth required pam_env.so readenv=1 envfile=/etc/default/locale
auth sufficient pam_listfile.so item=user sense=allow file=/etc/gdm/nopassusers onerr=fail #add this line
@include common-auth
auth optional pam_gnome_keyring.so
@include common-account
session required pam_limits.so
@include common-session
session optional pam_gnome_keyring.so auto_start
@include common-password

now simply restart gdm (or the whole machine) and try your new one-click login

/etc/init.d/gdm restart



Notes:
This means the keyring isn't unlocked, so you may have to type in your password anyway before your wireless connects.


references:
http://mirror.hamakor.org.il/archives/linux-il/05-2004/10149.html
http://www.kernel.org/pub/linux/libs/pam/Linux-PAM-html/sag-pam_listfile.html