Re: [Feature Request] Fingerprint prompting for tramp

[Michael Albinus]

N Winkel <nw1905@outlook.com> writes:

> Hi Tramp Development Team,

Hi Neri,

> Would it be possible to add the prompts sudo gives for fingerprint
> authentication to the prompts for tramp? Currently it does accept the
> fingerprint, however it doesn't show a prompt or give an option to
> cancel it and go to password authentication instead, instead timing
> out and erroring.
>
> When sudo prompts for fingerprint is gives "Place your finger on the
> fingerprint reader", times out with the message "Verification timed
> out" after 30 seconds and sends to password verification (at least
> when run from shell). Alternatively if you want to cancel fingerprint
> auth and go straight to password, you can send Ctrl+C.
>
> Currently when I try to use tramp (and don't use the fingerprint
> reader) it times out after 15 seconds with tramp-error: Timeout
> reached, see buffer ´*tramp/sudo root@localhost*´ for details, a
> buffer which contains "Place your finger on the fingerprint reader".
> With fprintd enabled in my /etc/pam.d/sudo I currently have no way of
> using password in tramp (unless I add a script that detects being
> within tramp and skips fprint).
>
> I hope this can be implemented! I should be able to test an
> implementation if someone can work on it (provided I find out how to)
> if needed.
>
> N.B. I initially asked this on Emacs StackExchange where it was
> suggested to request here.

It was me who has pointed you to the tramp-devel ML :-)

Meanwhile, I've tried to add some bits. Appended is a patch (for
tramp.el and tramp-sh.el), which is just my naïve implementation of the
feature. Note, that I have no fingerprint reader on my laptop; I've
grepped the respective fprintd messages from the sources. I cannot test myself.

The patch adds a new user option tramp-use-fingerprint. If it is non-nil
(the default), Tramp tries to support you in using the fingerprint
reader by a respective message. If the user option is nil, Tramp tries
to send ^C to the remote, cancelling the fingerprint session, in order
to fallback to password authentication.

Please install the recent Tramp 2.7.1.4 from GNU ELPA, and apply the
patch. Then test test test. I'm interested in both the successful and
failing cases.

Before running the tests, set tramp-verbose to 10. In case of problems,
pls send the respective Tramp debug buffer(s).

> Many Thanks,
> Neri

Best regards, Michael.

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