jcomito / rua

Build tool for Arch Linux providing control, review and jailed build options

RUA

RUA is a build tool for ArchLinux, AUR. Its features:

• Allows local patch application
• Provides detailed information:
  • warn if SUID files are present in an already built package, and show them
  • show upstream diff before building, or full diff if the package is new
  • see code problems in PKGBUILD via shellcheck, taking care of special variables
  • show INSTALL script (if present), executable and file list previews in already built package
• Minimize user distractions:
  • verify all packages once, build without interruptions
  • group built dependencies for batch review/install
• Uses a security namespace jail:
  • supports "offline" builds
  • builds in isolated filesystem, see safety section below
  • uses seccomp to limit available syscalls (e.g. the build cannot call ptrace)
  • the build cannot execute sudo (filesystem is mounted with nosuid)
• Written in Rust

Use

rua install xcalib # install or upgrade a package

rua search wesnoth

rua info freecad

rua upgrade # upgrade AUR packages. You can selectively ignore packages by adding them to IgnorePkg in pacman.conf (same as with non-AUR packages and pacman).

rua shellcheck path/to/my/PKGBUILD # run shellcheck on a PKGBUILD, discovering potential problems with the build instruction. Takes care of PKGBUILD-specific variables.

rua tarcheck xcalib.pkg.tar # if you already have a *.pkg.tar package built, run RUA checks on it (SUID, executable list, INSTALL script review etc).

rua builddir --offline /path/to/pkgbuild/directory # build a directory. Don't fetch any dependencies. Assumes a clean directory.

rua --help; rua subcommand --help # shows CLI help

Install dependencies

sudo pacman -S --needed git base-devel bubblewrap-suid lz shellcheck cargo

Install (the AUR way)

git clone https://aur.archlinux.org/rua.git
cd rua
makepkg -si

In the web interface, package is rua.

Install (the Rust way)

RUSTUP_TOOLCHAIN=stable cargo install --force rua

This does not include bash/zsh/fish completions, but everything else should work. If you use development version pacman-git, use cargo install --features git rua instead.

How it works / reviewing

When a new AUR package is fetched by RUA for the first time, it is stored in ~/.config/rua/pkg/pkg_name. This is done via git, with an empty branch as your currently accepted state.

If you review upstream changes and accept them, upstream is merged into your local branch. RUA will only allow you building once upstream is your ancestor, making sure you merged it.

When you later install a new version of the package, RUA will fetch the new version and show you the diff since your last review.

How it works / dependency grouping and installation

RUA will:

1. Fetch the AUR package and all recursive dependencies.
2. Prepare a summary of all pacman and AUR packages that will need installing. Show the summary to the user, confirm proceeding.
3. Iterate over all AUR dependencies and ask to review the repo-s. Once we know that user really accepts all recursive changes, proceed.
4. Propose installing all pacman dependencies.
5. Build all AUR packages of maximum dependency "depth".
6. Let the user review built artifacts (in batch).
7. Install them. If any more packages are left, go two steps up.

If you have a dependency structure like this:

your_original_package
├── dependency_a
│   ├── a1
│   └── a2
└── dependency_b
    ├── b1
    └── b2

RUA will thus interrupt you 3 times, not 7 as if it would be plainly recursive. It also won't disrupt you if it knows recursion breaks down the line (with unsatisfiable dependencies).

Limitations

• This tool focuses on AUR packages only, you cannot -Suy your system with it. Use pacman for that.
• Optional dependencies (optdepends) are not installed. They are skipped. Check them out manually when you review PKGBUILD.
• The tool does not handle versions. It will always install the latest version possible, and it will always assume that latest version is enough.
• Development packages such as "-git" packages are only rebuilt when running rua upgrade --devel. No version checks are done to avoid unnecessary rebuilds. Merge requests welcomed.
• Unless you explicitly enable it, builds do not share user home (~). This may result in maven/npm/cargo/whatever dependencies re-downloading with each build. See safety section below on how to whitelist certain directories.
• Environment variables "PKGDEST" and "BUILDDIR" of makepkg.conf are not supported. Packages are built in isolation from each other, artifacts are stored in standard locations of this tool.

Safety

RUA only adds build-time safety and install-time control. Once/if packages pass your review, they are as run-time safe as they were in the first place. Do not install AUR packages you don't trust.

When building packages, RUA uses the following filesystem isolation by default:

• Build directory is mounted read-write.
• Files "$GNUPGHOME"/pubring.kbx and "$GNUPGHOME"/pubring.gpg are mounted read-only (if exists). This allows signature verification to work.
• The rest of ~ is not visible to the build process, mounted under tmpfs.
• The rest of / is mounted read-only.
• You can whitelist/add your mount points by configuring "wrap_args". See examples in ~/.config/rua/wrap_args.d/ (none enabled by default).

As mentioned in the header, seccomp also applies to all builds, and there is a CLI option for offline builds.

Other

The RUA name can be read as "RUst Aur jail", also an inversion of "AUR".

This work was made possible by the excellent libraries of libalpm, raur, srcinfo and many others.

IRC: #rua @freenode.net

Project is shared under GPLv3+. For authors, see Cargo.toml and git history.