Gaze

Console login (TTY) ​

Gaze can authenticate the login prompt on a virtual terminal, the one you get on a server with no desktop or by switching to a free VT with Ctrl+Alt+F3.

Type your username, press Enter, and look at the camera. The password prompt is printed by pam_unix, not by login itself, so when Gaze succeeds first that prompt never appears and you go straight to a shell.

Setup ​

login uses the shared authentication stack, so on most distros enabling Gaze the usual way covers it:

bash
sudo pam-auth-update --package
bash
sudo authselect select gaze with-silent-lastlog --force

Debian's /etc/pam.d/login includes common-auth and Fedora's includes system-auth, so the profile you enable for sudo reaches the console too.

Arch Linux ​

Arch needs a manual step. Gaze deliberately stays out of /etc/pam.d/system-auth because pambase overwrites that file on upgrade (see PAM), and /etc/pam.d/login reaches Gaze only through that shared stack. Add Gaze to /etc/pam.d/login directly instead:

bash
staged=$(sudo mktemp /etc/pam.d/login.gaze.XXXXXX) && \
  sudo awk -v out="$staged" '
    /^[[:space:]]*auth[[:space:]]+(include|substack)[[:space:]]/ && !inserted {
        print "auth        sufficient    pam_gaze.so" > out
        inserted = 1
    }
    { print > out }
    END { if (!inserted) exit 1 }
' /etc/pam.d/login && \
  sudo install -m 644 "$staged" /etc/pam.d/login
sudo rm -f "$staged"

Two details of that command matter, because a mangled /etc/pam.d/login locks you out of every terminal:

  • The Gaze line goes immediately above auth include system-login, which is the line that pulls in the shared stack. Everything Arch puts before it, meaning pam_nologin and pam_securetty where it is used, is a veto that has to run first. Gaze is sufficient, so a face match returns from the stack right there and nothing printed after it runs.
  • awk writes the staged file itself rather than being piped into tee. A pipeline reports only the exit status of its last command, so a failing awk would still leave tee reporting success and install would happily replace your login stack with a truncated or empty file. Written this way, && sees awk's own status, and awk exits non-zero if it never found the include line.

The staging file is created by root inside /etc/pam.d on purpose. Building the new stack at a fixed path under /tmp would let any other local user pre-create it, and whatever they left there would become your authentication stack.

Check the result with cat /etc/pam.d/login before you log out.

WARNING

Keep a root shell open while you test this. A mistake in /etc/pam.d/login can lock you out of every virtual terminal.

Camera at the login prompt ​

No session exists before you log in, so there is no PipeWire to capture through and no ACL granting your user the camera. Gaze notices this and captures the seat's V4L2 device instead. gazed opens the camera, not the PAM module, so the confinement that applies to login itself is not in the way.

Pinning cameras.rgb to a pipewiresrc pipeline will not work here. Leave it as primary, which falls back to a V4L2 node when PipeWire cannot be reached, or pin it to usb:VVVV:PPPP to skip the failed attempt entirely. See Select Camera Source.

When Gaze will not use the seat camera ​

Gaze takes the seat device only when logind reports that seat0 has no active session and that no session on that seat belongs to another user.

Both halves matter. logind clears the active session whenever the foreground virtual terminal holds no session, which is also true when somebody else is logged in on a background terminal. So "no active session" on its own does not mean the seat is free, and Gaze does not treat it that way: if another user is logged in anywhere on the seat, console face authentication falls back to a password.

If logind cannot be reached at all, Gaze refuses rather than guessing.

Note also that an already-open camera is not closed when a session stops being active. A program left running in a background session can keep the device, so capture may fail as busy even when the seat looks free.

Time limits ​

login allows 60 seconds for the whole attempt by default (LOGIN_TIMEOUT in /etc/login.defs) and up to three tries (LOGIN_RETRIES). Each face attempt can use up to 12 seconds, and some distros add a delay after a failure, so repeated face failures can use the budget before you have typed anything. If that happens, login exits and the terminal returns to a fresh prompt.

Lower auth.start_delay_ms to nothing on this surface, and if you routinely fall back to a password, consider leaving Gaze off the console stack and using it for sudo and the lock screen instead.

Keyring ​

There is no password to hand to pam_gnome_keyring or pam_kwallet when you authenticate with your face, so a keyring unlocked at login will instead prompt you later. On a headless or server console this usually does not matter; on a machine where you start a desktop from the TTY, it does.

Turning it off ​

On Debian and Ubuntu, drop Gaze from the shared stack and re-add it only where you want it:

bash
sudo pam-auth-update --disable gaze gaze-simultaneous

Then follow Selective setup. On Arch, remove the pam_gaze.so line you added to /etc/pam.d/login.