nevaforget
d11b6e634e
Close the only exploitable auth bypass: validate VerifyStatus signal sender against fprintd's unique bus name. Fix fingerprint D-Bus lifecycle so devices are properly released on verify-match and async restarts check the running flag between awaits. Security: num_msg guard in PAM callback, symlink rejection for background_path, peek icon disabled, TOML parse errors logged, panic hook before logging. Performance: blur and avatar textures cached across monitors, release profile with LTO/strip.
32 lines
3.0 KiB
Markdown
32 lines
3.0 KiB
Markdown
# Decisions
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Architectural and design decisions for Moonlock, in reverse chronological order.
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## 2026-03-28 – Audit-driven security and lifecycle fixes (v0.6.0)
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- **Who**: Nyx, Dom
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- **Why**: Triple audit (quality, performance, security) revealed a critical D-Bus signal spoofing vector, fingerprint lifecycle bugs, and multi-monitor performance issues.
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- **Tradeoffs**: `cleanup_dbus()` extraction adds a method but clarifies the stop/match ownership; `running_flag: Rc<Cell<bool>>` adds a field but prevents race between async restart and stop; sender validation adds a check per signal but closes the only known auth bypass.
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- **How**: (1) Validate D-Bus VerifyStatus sender against fprintd's unique bus name. (2) Extract `cleanup_dbus()` from `stop()`, call it on verify-match. (3) `Rc<Cell<bool>>` running flag checked after await in `restart_verify_async`. (4) Consistent 3s D-Bus timeouts. (5) Panic hook before logging. (6) Blur and avatar caches shared across monitors. (7) Peek icon disabled. (8) Symlink rejection for background_path. (9) TOML parse errors logged.
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## 2026-03-28 – GPU blur via GskBlurNode replaces CPU blur
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- **Who**: Nyx, Dom
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- **Why**: CPU-side Gaussian blur (`image` crate) blocked the GTK main thread for 500ms–2s on 4K wallpapers at cold cache. Disk cache mitigated repeat starts but added ~100 lines of complexity.
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- **Tradeoffs**: GPU blur quality is slightly different (box-blur approximation vs true Gaussian), acceptable for wallpaper. Removes `image` and `dirs` dependencies entirely. No disk cache needed.
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- **How**: `Snapshot::push_blur()` + `GskRenderer::render_texture()` on `connect_realize`. Blur happens once on the GPU when the widget gets its renderer, producing a concrete `gdk::Texture`. Zero startup latency.
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## 2026-03-28 – Optional background blur via `image` crate (superseded)
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- **Who**: Nyx, Dom
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- **Why**: Consistent with moonset/moongreet — blurred wallpaper as lockscreen background is a common UX pattern
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- **Tradeoffs**: Adds `image` crate dependency (~15 transitive crates); CPU-side Gaussian blur at load time adds startup latency proportional to image size and sigma. Acceptable because blur runs once and the texture is shared across monitors.
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- **How**: `load_background_texture(bg_path, blur_radius)` loads texture, optionally applies `imageops::blur()`, returns `gdk::Texture`. Config option `background_blur: Option<f32>` in TOML.
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## 2026-03-28 – Shared wallpaper texture pattern (aligned with moonset/moongreet)
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- **Who**: Nyx, Dom
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- **Why**: Previously loaded wallpaper per-window via `Picture::for_filename()`. Multi-monitor setups decoded the JPEG redundantly. Blur feature requires texture pixel access anyway.
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- **Tradeoffs**: Slightly more code in main.rs (texture loaded before window creation), but avoids redundant decoding and enables the blur feature.
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- **How**: `load_background_texture()` in lockscreen.rs decodes once, `create_background_picture()` wraps shared `gdk::Texture` in `gtk::Picture`. Same pattern as moonset/moongreet.
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