[fprint] fprintd single sign on limitation

[Bastien Nocera]

Hey,

On Tue, 2018-11-13 at 14:50 +0800, Dave.Wang wrote:
> Dear,
>  
> I did some experiments as below:
> 1.      I found that it is necessary to choose which account to login
> first before identifying the corresponding finger.
> 2.      After I choose “account A”, I can’t identify the fingerprint
> which is corresponding to “account B” into “account B”

There's no support for "identification" in fprintd:
https://gitlab.freedesktop.org/libfprint/fprintd/issues/10

> We want to implement application of single sign on.

Single Sign-On (SSO) is something completely different:
https://en.wikipedia.org/wiki/Single_sign-on

> Is it possible to directly log in any account with its corresponding
> fingerprint, rather than pick the account first and then identify the
> finger?

It might be possible to integrate this with session logins, but, as a
first pass, support should be added to the daemon. We can then figure
out how to integrate it in the PAM module.

Cheers