Fingerprint Authentication: Support multi user-login scenario

[PRASAD HEGDE]

FP authentication doesn't work from the login screen when there is another user.
You have to login into any user with a password for first time, then we can use FP authentication for our next login attempts.

Ubuntu version : 20.04 LTS

[Sebastien Bacher (seb128)]

Thank you for your bug report, the description is not really clear,

Do you mean that if you have user A and B then
- log into user A
- close the session
- auth user A with a fingepritn works

but

- log into user A
- close the session
- auth user B with a fingerprint doesn't work
?

[PRASAD HEGDE (prasad-hegde-nagapati)]

FP authentication doesn't work when there are more than one user in Ubuntu 20.04

Steps to reproduce

1. Navigate to Activities and click users
2. Click on Fingerprint login for the respective user
3. Enroll a FP
4. Lock the laptop
5. Authenticate with enrolled FP
6. Observe FP auth is successful
7. Create another user in Ubuntu 20.04
8. Logout from the system
9. Place the enrolled finger on sensor
10. Observe that FP authentication isn't success

Expected

FP authentication should happen for respective user from login screen

[Marco Trevisan (Treviño) (3v1n0)]

Also gnome-shell is part of this game, however the way to handle this is select the user to login first.

However, I've already prepared some work to get user identification possible: https://gitlab.freedesktop.org/libfprint/fprintd/-/merge_requests/113

Work on the PAM module, GDM and gnome-shell are still required though

[prafulla chandra kota (prafullakota)]

Multi user FP identification is working fine now, defect can be closed.

[prafulla chandra kota (prafullakota)]

22.04: FP identify is working fine now from login screen by selecting respective user and swipe the finger.