96 lines
No EOL
3.9 KiB
Markdown
96 lines
No EOL
3.9 KiB
Markdown
# fingerprintd
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Fingerprint daemon for the Fairphone 6 (`milos`, SM7635) on mainline Linux.
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`fingerprintd-core` is a static library with no GLib, no libqcomtee and no
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system headers. Everything in it is a wire format or a state machine that was
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recovered by reverse-engineering, so all of it is pinned by tests that run on a
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dev box with no phone, no TEE and no sensor. The daemon shell holds everything
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that touches hardware.
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```
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fprintd-enroll -f right-index-finger user ten stages, enroll-completed
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fprintd-list user - #0: right-index-finger
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fprintd-verify user (wrong finger) verify-no-match, on the first press
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fprintd-verify user (enrolled finger) verify-match, on the first press
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```
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## Lock-screen unlock
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Two routes, both on by default:
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- **PAM.** The daemon provides `fprintd`, so a lock screen that runs
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`pam_fprintd` beside its password prompt unlocks by finger the usual way.
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Plasma's does (`kde-fingerprint`; the `fingerprint-auth` and `postlogin`
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services it needs are shipped here). Phosh's cannot: its PAM conversation
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answers every prompt with the password, so a fingerprint module in its stack
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would only stall the password behind the fingerprint timeout.
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- **Standby.** While the session in front on its seat is locked and the
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display is on, the daemon runs a verify of its own and answers a match with
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logind's `Session.Unlock`, which Phosh honours. No verify runs while the
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display is off (an open verify polls the sensor at ~5 Hz; the display state
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comes from the backlight's `bl_power` or the panel's DRM `dpms`, and a
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device with neither is treated as always on). Any fprintd client takes
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precedence: a `Claim` cancels the standby verify, a `Release` re-arms it.
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Only fingers named in that session owner's map unlock, and the map is
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re-read at every arm, so a finger deleted while locked stops counting at
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once. Per-finger `no-unlock` rules apply here too, and every match is
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announced as `FingerMatched` for the session agent. `--standby-unlock=off`
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disables it.
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## Per-finger macros
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The trustlet reports *which* finger matched, so a finger can mean more than
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"it was you". Two files, in two trust domains:
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- **`~/.config/fingerprintd/fingers.conf`** runs a command as you, in your
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session. This is how a finger opens an application.
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- **`/etc/fingerprintd/actions.conf`** runs a command as root, and can mark a
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finger as one that never unlocks.
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### In your session: `fingers.conf`
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```
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# ~/.config/fingerprintd/fingers.conf
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right-ring-finger kde-open camera
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left-index-finger plasma-settings
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left-thumb sh -c 'notify-send "hello from a finger"'
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```
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- using these requires the fingerprintd-agent service to be running.
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### As root: `actions.conf`
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```
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# /etc/fingerprintd/actions.conf
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# <finger> [no-unlock] [absolute command...]
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right-ring-finger /usr/local/bin/toggle-something
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left-little-finger no-unlock /etc/fingerprintd/panic.sh
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left-thumb no-unlock
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```
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- `no-unlock`: the finger matches and the client is told it did not. PAM
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sees `verify-no-match`, the standby unlock stays locked. The command, if
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there is one, runs regardless.
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- the command: an absolute path, run by root through `/bin/sh -c` with a
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fixed `PATH` and `FINGERPRINTD_FINGER` set to the finger's name, detached
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from the daemon with its stdio on `/dev/null`, so it may block or reboot
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the phone without stalling the sensor.
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- a line needs at least one of the two, and a finger gets at most one line.
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- editing this file requires a restart of the fingerprintd service before changes take effect.
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## Runtime dependencies
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The `focal64` trustlet is proprietary and is not in this repo. It is
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extracted from the device's own stock Android partition on first boot by the
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`fp6-vendor-blobs` mechanism, the same way other firmware in fp6-img is.
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## License
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GPL-3.0-only, see LICENSE.
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## Copyright
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Copyright (C) 2026 Catcrafts® catcrafts.net |