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I have both fingerprint and password login enabled. However each only works when the corresponding prompt is visible.

  • When the fingerprint prompt is displayed, entering passwords doesn't work.

  • When the password field is displayed, fingerprint scanning doesn't work.

  • When both fingerprint prompt and password field are displayed (when unlocking and the fingerprint reading times out), fingerprint scanning doesn't work but password entry does.

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Is there a way to have both login methods work regardless of which prompt is displayed?

1 Answer 1

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+50

It might not be possible as of now. I am listing below what suggests it is (at least) complicated, and things you can try.

  1. As per this,

At the moment, you cannot type in your password right away when you are asked for fingerprint. You need to make the fingerprint authentication fail first (swipe wrong finger or let it time out) before you are asked for password. This is a limitation of PAM because its modules mustn't be threaded and hence cannot support multiple means of authentication at the same time. (The old ThinkFinger used to do this, but it was a gross hack which caused many troubles.) A possible solution to this limitation is to make gdm, screensaver and policykit-1 support multiple alternative PAM stacks.

I did not try the suggestion there (which is no more than that, a suggestion), but I found no references to anyone succeeding.

  1. As per this,

pam_fprintd doesn't support entering either the password or a fingerprint, as pam_thinkfinger does, because it's a gross hack, and could be fixed by having the login managers run 2 separate PAM stacks

Lights of hope, YMMV:

  1. See item 1 above.
  2. As per this, there is a fork https://github.com/zsxsoft/libfprint-fprintd, although it is old and not maintained.

Related:

  1. https://unix.stackexchange.com/questions/332149/how-to-login-with-both-password-and-fingerprint
  2. https://unix.stackexchange.com/questions/207360/use-multiple-pam-login-methods-at-once
  3. https://www.redhat.com/sysadmin/pam-authconfig ("You can set multiple options at the same time...")
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    Thanks for answering! It may just be that there is no way in Linux do this currently. I've upvoted and If no one comes up with a solution in the next few days I'll accept this answer. Apr 22, 2021 at 23:52
  • @user15656060 - Note that other Linux flavors may have this feature available. Apr 23, 2021 at 1:01

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