buffybox/unl0kr

Unl0kr

Disk unlocker for the initramfs based on LVGL.

[[TOC]]

About

Unl0kr is an osk-sdl clone written in LVGL and rendering directly to the Linux framebuffer. As a result, it doesn't depend on GPU hardware acceleration.

For some background on how unl0kr came to be, see postmarketOS/osk-sdl#121.

Status

While we continue to tweak and extend Unl0kr, it is deemed fully functional. Unl0kr has been set up as the default disk unlocker on postmarketOS and was also packaged for other distrubtions including Arch Linux and Debian.

Here are a few highlights of the currently supported features:

• Password-entry UI including on-screen keyboard using either the Linux framebuffer or the DRM subsystem
• Automatic input device discovery (both at start-up and runtime) for keyboards, mice, trackpads and touch screens
• On-screen keyboard control via:
  • One or more mice / trackpads (including cursor)
  • One or more hardware keyboards (including support for different layouts using XKB)
  • Touchscreen
• Keyboard layout configuration (currently supported: de, es, fr, us) including switching the layout at runtime
• Toggling on-screen keyboard with slide in/out animation
• Theming support including switching between light and dark theme at runtime
• Disclosing and hiding entered password at runtime
• Shutting down the device via a soft button

Screenshots of the currently available themes may be found in the screenshots folder.

Usage

Unl0kr includes a man page. Additionally, you can get an overview of available command line options by running it with the -h or --help argument.

$ unl0kr --help
Usage: unl0kr [OPTION]

Unl0kr values the CRYPTTAB_TRIED variable. Upon completion, the entered
password is printed to STDOUT. All other output happens on STDERR.

Mandatory arguments to long options are mandatory for short options too.
  -C, --config-override     Path to a config override file. Can be supplied
                            multiple times. Config files are merged in the
                            following order:
                            * /etc/unl0kr.conf
                            * /etc/unl0kr.conf.d/* (alphabetically)
                            * Override files (in supplied order)
  -g, --geometry=NxM[@X,Y]  Force a display size of N horizontal times M
                            vertical pixels, offset horizontally by X
                            pixels and vertically by Y pixels
  -d  --dpi=N               Override the display's DPI value
  -h, --help                Print this message and exit
  -v, --verbose             Enable more detailed logging output on STDERR
  -V, --version             Print the unl0kr version and exit

For an example configuration file, see unl0kr.conf.

Development

Dependencies

• inih
• lvgl (git submodule / linked statically)
• squeek2lvgl (linked statically)
• libinput
• libudev
• libxkbcommon
• libdrm (optional, required for the DRM backend)
• evdev kernel module
• scdoc (for generating the man page)

Building & running

Some of unl0kr's dependencies are included as git submodules in this repository. You can clone the repository and initialise the submodules with

$ git clone https://gitlab.com/postmarketOS/buffybox.git
$ cd buffybox
$ git submodule init
$ git submodule update

When pulling changes from the remote later, either use git pull --recurse-submodules or manually run git submodule update as needed after pulling.

Once you have the sources, you can build the app and run it in a VT. Unless your user account has special privileges, sudo will be needed to access input device files.

$ meson _build
$ meson compile -C _build
$ sudo chvt 2
$ sudo ./_build/unl0kr

With meson <0.55 use ninja instead of meson compile.

Valgrind

Using C without Valgrind is like skydiving without a parachute.

To be able to use Valgrind, add default_options: ['optimization=g'] in the project section of meson.build and rebuild. Afterwards you can run the application with Valgrind's leaks check enabled via

sudo valgrind --leak-check=yes ./_build/unl0kr

Backends

Unl0kr supports multiple LVGL display drivers, referred to as "backends".

• fbdev
• drm (optional)

The active backend can be selected via the general.backend option in the configuration file.

Note that if libdrm is installed, the DRM backend will be compiled in automatically. It's possible to prevent this behaviour by passing the with-drm option to meson.

$ meson _build -Dwith-drm=disabled

Fonts

In order to work with LVGL, fonts need to be converted to bitmaps, stored as C arrays. Unl0kr currently uses a combination of the OpenSans font for text and the FontAwesome font for pictograms. For both fonts only limited character ranges are included to reduce the binary size. To (re)generate the C file containing the combined font, run the following command

$ ./regenerate-fonts.sh

Below is a short explanation of the different unicode ranges used above.

• OpenSans
  • Basic Latin (0x0020-0x007F)
  • Latin-1 supplement (0x00A0-0x00FF)
  • Latin extended A (0x0100-0x017F)
  • Greek and Coptic (0x0370-0x03FF)
  • General punctuation (0x2000-0x206F)
  • Currency symbols (0x20A0-0x20CF)
  • Mathematical operators (0x2200-0x22FF)
• FontAwesome
  • Standard LV_SYMBOL_* glyphs (0xF001,0xF008,0xF00B,0xF00C,0xF00D,0xF011,0xF013,0xF015,0xF019,0xF01C,0xF021,0xF026,0xF027,0xF028,0xF03E,0xF0E0,0xF304,0xF043,0xF048,0xF04B,0xF04C,0xF04D,0xF051,0xF052,0xF053,0xF054,0xF067,0xF068,0xF06E,0xF070,0xF071,0xF074,0xF077,0xF078,0xF079,0xF07B,0xF093,0xF095,0xF0C4,0xF0C5,0xF0C7,0xF0C9,0xF0E7,0xF0EA,0xF0F3,0xF11C,0xF124,0xF158,0xF1EB,0xF240,0xF241,0xF242,0xF243,0xF244,0xF287,0xF293,0xF2ED,0xF55A,0xF7C2,0xF8A2)
  • adjust (0xF042)
  • arrow-alt-circle-up (0xF35B)
  • chevron-left (0xF053)

Keyboard layouts

Unl0kr uses squeekboard layouts converted to C via squeek2lvgl. To regenerate the layouts, ensure that you have pipenv installed (e.g. via pip install --user pipenv) and then run

$ ./regenerate-layouts.sh

from the root of the repository.

Generating screenshots

To generate screenshots in a variety of common sizes, build unl0kr and then run

$ sudo ./regenerate-screenshots _build/unl0kr

where _build/unl0kr is the location of the unl0kr binary. Note that you may have to adapt some of the settings inside the script depending on the device you're using to generate the screenshots.

Screen recording

For demonstration purposes you can record the framebuffer device, e.g. with ffmpeg:

$ sudo ffmpeg -f fbdev -i /dev/fb0 -r 24 -c:v libx264 -b:v 500k demo.avi

Acknowledgements

The lv_port_linux_frame_buffer project served as a starting point for the codebase.

License

Unl0kr is licensed under the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

The OpenSans font is licensed under the Apache License 2.0.

The FontAwesome font is licensed under the Open Font License version 1.1.