linkdata / rinse

Document cleaner

rinse

Web service that converts untrusted documents to image-based PDF:s in a sandbox.

Requirements

• podman is required.
• gVisor is highly recommended, but optional.
• 2GB+ of disk space on /tmp, as the conversion process can use up a lot of space.

Container security

The container is run with read-only filesystem, no privileges and no network. If you have gVisor installed and run rinse as root (which gVisor requires), gVisor will be used to further sandbox the container.

Process

First, a temporary directory is created for the job. This will be mounted in the container as /var/rinse.

The original document is renamed to input with it's extension preserved.

Then, each of these stages run in their own container, which is destroyed as soon as the stage is complete. rinse removes files as soon as possible after each stage. At the end, only the final document-rinsed.pdf file remains on disk until the job is deleted, which also deletes the final PDF.

If the language is to be auto-detected, Apache Tika is used to do so.

If the document is not a PDF, LibreOffice is used to try to covert it to one, and if successful, the original document is deleted.

The input.pdf file is converted to a set of image files using pdftoppm.

The set of images files is OCR-ed and processed into a PDF using tesseract.