System Contracts

Stable contracts. Do not change without updating this document.

Binaries

Binary	Crate	Purpose
`facelock`	facelock-cli	Unified CLI (daemon, auth, enroll, test, setup, etc.)
`pam_facelock.so`	pam-facelock	PAM authentication module

CLI Subcommands

Command	Purpose
`facelock setup`	Download models, create directories
`facelock setup --systemd`	Install/enable systemd units
`facelock setup --pam`	Install PAM module to `/etc/pam.d/`
`facelock enroll`	Capture and store a face
`facelock test`	Test face recognition
`facelock list`	List enrolled face models
`facelock remove <id>`	Remove a specific model
`facelock clear`	Remove all models for a user
`facelock preview`	Live camera preview
`facelock devices`	List V4L2 cameras
`facelock status`	Check system status
`facelock config`	Show/edit configuration
`facelock daemon`	Run persistent daemon
`facelock auth --user X`	One-shot auth (PAM helper)
`facelock tpm status`	TPM status
`facelock bench`	Benchmarks
`facelock restart`	Restart daemon

Operating Modes

Mode	Config	PAM Behavior	CLI Behavior
Daemon	`daemon.mode = "daemon"` (default)	D-Bus IPC to daemon	Uses daemon if available, falls back to direct
Oneshot	`daemon.mode = "oneshot"`	Spawns `facelock auth`	Operates directly (no daemon)

The CLI silently falls back to direct mode when the daemon is not available on D-Bus, regardless of config mode.

facelock auth Exit Codes

Code	Meaning	PAM Code
0	Face matched	PAM_SUCCESS
1	No match / timeout / dark	PAM_AUTH_ERR
2	Error / no enrolled faces	PAM_IGNORE

Filesystem Paths

Path	Owner	Mode	Purpose
`/etc/facelock/config.toml`	root:root	644	Configuration
`/var/lib/facelock/facelock.db`	root:facelock	640	Face embeddings
`/var/lib/facelock/models/`	root:root	755	ONNX models
`/var/log/facelock/snapshots/`	root:facelock	750	Auth snapshots
`/usr/bin/facelock`	root:root	755	CLI binary
`/lib/security/pam_facelock.so`	root:root	755	PAM module

All paths overridable via config. FACELOCK_CONFIG env var overrides config location.

Config Schema

TOML format. All keys optional -- camera auto-detected, sensible defaults for everything. See Configuration for the full reference.

Sections

Section	Key fields
`[device]`	`path` (Option), `max_height`, `rotation`
`[recognition]`	`threshold`, `timeout_secs`, `detector_model`, `embedder_model`, `threads`, `execution_provider`
`[daemon]`	`mode` (DaemonMode enum), `model_dir`, `idle_timeout_secs`
`[storage]`	`db_path`
`[security]`	`require_ir`, `require_frame_variance`, `min_auth_frames`, `abort_if_ssh`, `abort_if_lid_closed`, rate_limit sub-section
`[notification]`	`mode` (off/terminal/desktop/both), `notify_prompt`, `notify_on_success`, `notify_on_failure`
`[snapshots]`	`mode` (off/all/failure/success), `dir`
`[encryption]`	`method` (none/keyfile/tpm), `key_path`, `sealed_key_path`
`[audit]`	`enabled`, `path`, `rotate_size_mb`
`[tpm]`	`pcr_binding`, `pcr_indices`, `tcti`

Camera Auto-Detection

When device.path is omitted:

Enumerate /dev/video0 through /dev/video63
Filter to VIDEO_CAPTURE devices
Prefer IR cameras (name contains "ir"/"infrared", or supports GREY/Y16 format)
Fall back to first available device

Database Schema

SQLite with WAL mode and foreign keys:

CREATE TABLE face_models (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    user TEXT NOT NULL,
    label TEXT NOT NULL,
    created_at INTEGER NOT NULL,
    UNIQUE(user, label)
);

CREATE TABLE face_embeddings (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    model_id INTEGER NOT NULL REFERENCES face_models(id) ON DELETE CASCADE,
    embedding BLOB NOT NULL  -- 512 x f32 = 2048 bytes
);

D-Bus system bus (org.facelock.Daemon). Only used in daemon mode. The daemon exposes a D-Bus interface on the system bus, and both the PAM module and CLI connect as D-Bus clients. Access is controlled by D-Bus system bus policy (/etc/dbus-1/system.d/org.facelock.Daemon.conf).

Outcome	PAM Code
Face matched	`PAM_SUCCESS` (0)
No match	`PAM_AUTH_ERR` (7)
Daemon unavailable / error	`PAM_IGNORE` (25)
Timeout	`PAM_AUTH_ERR` (7)

PAM module never blocks indefinitely. All operations have timeouts.

Syslog Format

pam_facelock(<service>): <result> for user <username>

Anti-Spoofing

Defense	Config	Default
IR camera enforcement	`security.require_ir`	true
Frame variance check	`security.require_frame_variance`	true
Landmark liveness	`security.require_landmark_liveness`	false
Minimum auth frames	`security.min_auth_frames`	3
Variance threshold	`FRAME_VARIANCE_THRESHOLD`	0.998

These defaults must not be weakened without security review.

Models

Model	File	Size	Default
SCRFD 2.5G	`scrfd_2.5g_bnkps.onnx`	~3MB	Yes
ArcFace R50	`w600k_r50.onnx`	~166MB	Yes
SCRFD 10G	`det_10g.onnx`	~16MB	Optional
ArcFace R100	`glintr100.onnx`	~249MB	Optional

Configurable via recognition.detector_model and recognition.embedder_model.

Facelock Documentation