The fingerprint sensor on Lenovo Thinkpad T480s is not supported by libfprint, so you can’t use it out of the box. Thankfully, there’s a project called python-validity based on open-fprintd that’s easy to set up in, like, 5 minutes.
Setup
python-validity is available from open-fprintd PPA. I found that you can use Ubuntu Kinetic packages on Debian Bullseye without issues.
To add the PPA repository and install the necessary utilities, run the following commands:
sudo wget 'https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x2937db010da51096cd4277ff8d4c774ba6d18f90' -O /etc/apt/trusted.gpg.d/uunicorn.asc
echo -e 'deb [signed-by=/etc/apt/trusted.gpg.d/uunicorn.asc] https://ppa.launchpadcontent.net/uunicorn/open-fprintd/ubuntu kinetic main\n#deb-src [signed-by=/etc/apt/trusted.gpg.d/uunicorn.asc] https://ppa.launchpadcontent.net/uunicorn/open-fprintd/ubuntu kinetic main' | sudo tee /etc/apt/sources.list.d/uunicorn-open-fprintd.list
sudo apt update && sudo apt install -V open-fprintd fprintd-clients python3-validity
Afterward, run the fprintd-enroll command and scan your fingerprint multiple times. For accurate fingerprint detection, it helps to scan your fingerprint at slightly different angle each time.
fprintd-enroll
Finally, enable the sudo authentication with the fingerprint method:
sudo pam-auth-update
Suspend/hibernate fingerprint sensor fix
I had a problem with the fingerprint sensor not working when the laptop was resuming from suspend and hibernate. In my case, enabling open-fprintd-resume and open-fprintd-suspend didn’t help, but a custom one-shot Systemd unit (as suggested on the Arch wiki did the trick.
This one-shot simply restarts open-fprintd and python3-validity services when resuming from suspend/hibernate. To install it, simply run:
cat << EOF | sudo tee /etc/systemd/system/fingerprint-restart.service
[Unit]
Description=Restart services to fix fingerprint integration
After=suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target
[Service]
Type=oneshot
ExecStart=systemctl restart open-fprintd.service python3-validity.service
[Install]
WantedBy=suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target
EOF
sudo systemctl daemon-reload
sudo systemctl enable fingerprint-restart.service
Oh, would you look at the time! Exactly 5 minutes 🙂