Bug 448683 - Password wont be accepted when fingerprint is configured
Summary: Password wont be accepted when fingerprint is configured
Status: RESOLVED UPSTREAM
Alias: None
Product: kscreenlocker
Classification: Plasma
Component: general (show other bugs)
Version: 5.23.90
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-01-18 00:32 UTC by Matt
Modified: 2023-05-20 14:46 UTC (History)
4 users (show)

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Latest Commit:
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Description Matt 2022-01-18 00:32:06 UTC
SUMMARY
With Fingerprints enrolled, putting in my password is not accepted as a valid unlocking method. It prompts for the fingerprint after entering password and enter, then says unlocking failed


STEPS TO REPRODUCE
1. lock screen
2. enter password
3. promted for fingerprint, even tho password has been supplied
4.enter password again
5. unlocking failed

OBSERVED RESULT

Only fingerprint can unlock my session

EXPECTED RESULT

A password unlocked session

SOFTWARE/OS VERSIONS

Linux/KDE Plasma:  Fedora KDE 35
KDE Plasma Version: 5.23.90
KDE Frameworks Version: 5.90
Qt Version: 5.15

ADDITIONAL INFORMATION
I am using Marc Deop's plasma beta build for Fedroa https://copr.fedorainfracloud.org/coprs/marcdeop/plasma/
Comment 1 Nate Graham 2022-01-20 21:30:18 UTC
This message is coming straight from fprint, so it's a finger recognition issue in fprint itself. Unfortunately there's nothing we can do about it in KDE code.

I sometimes get the same thing and have to do it a few times before my finger is accepted. And I've notices that when my fingers are wet, it won't work. I was unable to unlock right after coming out the shower the other day lol
Comment 2 Matt 2022-01-21 00:25:09 UTC
isnt it a kscreenlocker logic issue tho? - if a password has been supplied, it should straight out skip the fprint part and unlock normally
Comment 3 Nate Graham 2022-01-21 00:33:49 UTC
Ohh! Sorry, I misread the issue.

Nonetheless, it is still an upstream issue, albeit a different one. When fprint auth is in use, polkit prevents using your password. You can see this in non-kscreenlocker polkit auth prompts as well. It really shouldn't do this. But I think this is an issue in polkit itself.

(CCing David Edmundson who can correct me if I'm wrong)
Comment 4 Matt 2022-02-01 01:00:39 UTC
I was looking further into this and came across the archwiki suggestion (https://wiki.archlinux.org/title/Fprint#Login_configuration) for /etc/pam.d/kde config file to add 

auth		sufficient  	pam_unix.so try_first_pass likeauth nullok

essentially if password null, ask for fprint, but it looks like plasma generates these files using authselect, so I was hesitant to mess with them as I dont really want to break my config