274 lines
8.8 KiB
Markdown
274 lines
8.8 KiB
Markdown
## Piston
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Piston is the underlying engine for running untrusted and possibly malicious
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code that originates from EMKC contests and challenges. It's also used in the
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Engineer Man Discord server via [felix bot](https://github.com/engineer-man/felix).
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#### Installation
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```
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# clone and enter repo
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git clone https://github.com/engineer-man/piston
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cd piston/lxc
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# install dependencies
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# centos:
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yum install -y epel-release
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yum install -y lxc lxc-templates debootstrap libvirt
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systemctl start libvirtd
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# ubuntu server 18.04:
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apt install lxc lxc-templates debootstrap libvirt0
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# arch:
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sudo pacman -S lxc libvirt unzip
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# everything else:
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# not documented, please open pull requests with commands for debian/arch/macos
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# create and start container
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lxc-create -t download -n piston -- --dist ubuntu --release bionic --arch amd64
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./start
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# open a shell to the container
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./shell
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# install all necessary piston dependencies
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echo 'source /opt/.profile' >> /opt/.bashrc
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echo 'export HOME=/opt' >> /opt/.profile
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echo 'export TERM=linux' >> /opt/.profile
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export HOME=/opt
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export TERM=linux
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sed -i 's/\/root/\/opt/' /etc/passwd
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sed -i \
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's/http:\/\/archive.ubuntu.com\/ubuntu/http:\/\/mirror.math.princeton.edu\/pub\/ubuntu/' \
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/etc/apt/sources.list
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apt-get update
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apt-get install -y \
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nano wget build-essential pkg-config libxml2-dev \
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libsqlite3-dev mono-complete curl cmake libpython2.7-dev \
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ruby libtinfo-dev
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# install python2
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# final binary: /opt/python2/Python-2.7.17/python -V
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cd /opt && mkdir python2 && cd python2
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wget https://www.python.org/ftp/python/2.7.17/Python-2.7.17.tar.xz
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unxz Python-2.7.17.tar.xz
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tar -xf Python-2.7.17.tar
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cd Python-2.7.17
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./configure
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# open Modules/Setup and uncomment zlib line
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make
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echo 'export PATH=$PATH:/opt/python2/Python-2.7.17' >> /opt/.profile
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source /opt/.profile
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# install python3
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# final binary: /opt/python3/Python-3.8.2/python -V
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cd /opt && mkdir python3 && cd python3
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wget https://www.python.org/ftp/python/3.8.2/Python-3.8.2.tar.xz
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unxz Python-3.8.2.tar.xz
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tar -xf Python-3.8.2.tar
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cd Python-3.8.2
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./configure
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make
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ln -s python python3.8
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echo 'export PATH=$PATH:/opt/python3/Python-3.8.2' >> /opt/.profile
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source /opt/.profile
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# install node.js
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# final binary: /opt/nodejs/node-v12.16.1-linux-x64/bin/node -v
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cd /opt && mkdir nodejs && cd nodejs
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wget https://nodejs.org/dist/v12.16.1/node-v12.16.1-linux-x64.tar.xz
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unxz node-v12.16.1-linux-x64.tar.xz
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tar -xf node-v12.16.1-linux-x64.tar
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echo 'export PATH=$PATH:/opt/nodejs/node-v12.16.1-linux-x64/bin' >> /opt/.profile
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source /opt/.profile
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# install typescript
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# final binary: /opt/nodejs/node-v12.16.1-linux-x64/bin/tsc -v
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/opt/nodejs/node-v12.16.1-linux-x64/bin/npm i -g typescript
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# install golang
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# final binary: /opt/go/go/bin/go version
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cd /opt && mkdir go && cd go
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wget https://dl.google.com/go/go1.14.1.linux-amd64.tar.gz
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tar -xzf go1.14.1.linux-amd64.tar.gz
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echo 'export PATH=$PATH:/opt/go/go/bin' >> /opt/.profile
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echo 'export GOROOT=/opt/go/go' >> /opt/.profile
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echo 'export GOCACHE=/tmp' >> /opt/.profile
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source /opt/.profile
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# install php
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# final binary: /usr/local/bin/php -v
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cd /opt && mkdir php && cd php
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wget https://www.php.net/distributions/php-7.4.4.tar.gz
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tar -xzf php-7.4.4.tar.gz
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cd php-7.4.4
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./configure
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make
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make install
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# install rust
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# final binary: /opt/.cargo/bin/rustc --version
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curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
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echo 'export PATH=$PATH:/opt/.cargo/bin' >> /opt/.profile
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source /opt/.profile
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# install swift
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# final binary: /opt/swift/swift-5.1.5-RELEASE-ubuntu18.04/usr/bin/swift --version
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cd /opt && mkdir swift && cd swift
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wget https://swift.org/builds/swift-5.1.5-release/ubuntu1804/swift-5.1.5-RELEASE/swift-5.1.5-RELEASE-ubuntu18.04.tar.gz
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tar -xzf swift-5.1.5-RELEASE-ubuntu18.04.tar.gz
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echo 'export PATH=$PATH:/opt/swift/swift-5.1.5-RELEASE-ubuntu18.04/usr/bin' >> /opt/.profile
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source /opt/.profile
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# install nasm
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# final binary: /opt/nasm/nasm-2.14.02/nasm -v
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cd /opt && mkdir nasm && cd nasm
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wget https://www.nasm.us/pub/nasm/releasebuilds/2.14.02/nasm-2.14.02.tar.gz
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tar -xzf nasm-2.14.02.tar.gz
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cd nasm-2.14.02
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./configure
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make
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echo 'export PATH=$PATH:/opt/nasm/nasm-2.14.02' >> /opt/.profile
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source /opt/.profile
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# install java
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# final binary: /opt/java/jdk-14/bin/java -version
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cd /opt && mkdir java && cd java
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wget https://download.java.net/java/GA/jdk14/076bab302c7b4508975440c56f6cc26a/36/GPL/openjdk-14_linux-x64_bin.tar.gz
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tar -xzf openjdk-14_linux-x64_bin.tar.gz
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echo 'export PATH=$PATH:/opt/java/jdk-14/bin' >> /opt/.profile
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source /opt/.profile
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# install julia
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#final binary: /opt/julia/julia-1.4.1/bin/julia --version
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cd /opt && mkdir julia && cd julia
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wget https://julialang-s3.julialang.org/bin/linux/x64/1.4/julia-1.4.1-linux-x86_64.tar.gz
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tar -xzf julia-1.4.1-linux-x86_64.tar.gz
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echo 'export PATH=$PATH:/opt/julia/julia-1.4.1/bin' >> /opt/.profile
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source /opt/.profile
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# install kotlin
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# final binary: /opt/kotlinc/bin/kotlinc -version
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cd /opt
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wget https://github.com/JetBrains/kotlin/releases/download/v1.3.72/kotlin-compiler-1.3.72.zip
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unzip kotlin-compiler-1.3.72.zip
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rm kotlin-compiler-1.3.72.zip
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echo 'export PATH=$PATH:/opt/kotlinc/bin' >> /opt/.profile
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source /opt/.profile
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# install elixir and erlang
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# final binary: /opt/elixir/bin/elixir --version
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# erlang
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cd /opt && mkdir erlang && cd erlang
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wget http://erlang.org/download/otp_src_23.0.tar.gz
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gunzip -c otp_src_23.0.tar.gz | tar xf -
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cd otp_src_23.0 && ./configure
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make
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echo 'export PATH=$PATH:/opt/erlang/otp_src_23.0/bin' >> /opt/.profile
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source /opt/.profile
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# elixir
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cd /opt && mkdir elixir && cd elixir
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wget https://github.com/elixir-lang/elixir/releases/download/v1.10.3/Precompiled.zip
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mkdir elixir-1.10.3 && unzip Precompiled.zip -d elixir-1.10.3/
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echo 'export PATH=$PATH:/opt/elixir/elixir-1.10.3/bin' >> /opt/.profile
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source /opt/.profile
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# install emacs
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# final binary: /opt/emacs/emacs-26.3/src/emacs --version
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cd /opt && mkdir emacs && cd emacs
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wget https://mirrors.ocf.berkeley.edu/gnu/emacs/emacs-26.3.tar.xz
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tar -xf emacs-26.3.tar.xz
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cd emacs-26.3
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./configure --with-gnutls=no
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echo 'export PATH=$PATH:/opt/emacs/emacs-26.3/src' >> /opt/.profile
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source /opt/.profile
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# create runnable users and apply limits
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for i in {1..150}; do
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useradd -M runner$i
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usermod -d /tmp runner$i
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echo "runner$i soft nproc 64" >> /etc/security/limits.conf
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echo "runner$i hard nproc 64" >> /etc/security/limits.conf
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echo "runner$i soft nofile 2048" >> /etc/security/limits.conf
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echo "runner$i hard nofile 2048" >> /etc/security/limits.conf
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done
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# cleanup
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rm -rf /home/ubuntu
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chmod 777 /tmp
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# leave container
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exit
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# optionally run tests
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cd ../tests
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./test_all_lxc
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```
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#### CLI Usage
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- `lxc/execute [language] [file path] [arg]...`
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#### API Usage
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To use the API, it must first be started. To start the API, run the following:
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```
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cd api
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./start
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```
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The Piston API exposes one endpoint at `http://127.0.0.1:2000/execute`.
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This endpoint takes the following JSON payload and expects at least the language and source. If
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source is not provided, a blank file is passed as the source.
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```json
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{
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"language": "js",
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"source": "console.log(process.argv)",
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"args": [
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"1",
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"2",
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"3"
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]
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}
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```
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A typical response when everything succeeds will be similar to the following:
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```json
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{
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"ran": true,
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"language": "js",
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"version": "12.13.0",
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"output": "[ '/usr/bin/node',\n '/tmp/code.code',\n '1',\n '2',\n '3' ]"
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}
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```
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If an invalid language is supplied, a typical response will look like the following:
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```json
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{
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"code": "unsupported_language",
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"message": "whatever is not supported by Piston"
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}
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```
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#### Supported Languages
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Currently python2, python3, c, c++, go, node, ruby, r, c#, nasm, php, java,
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swift, brainfuck, rust, bash, awk, and typescript is supported.
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#### Principle of Operation
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Piston utilizes LXC as the primary mechanism for sandboxing. There is a small API written in Go which takes
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in execution requests and executes them in the container. High level, the API writes
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a temporary source and args file to `/tmp` and that gets mounted read-only along with the execution scripts into the container.
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The source file is either ran or compiled and ran (in the case of languages like c, c++, c#, go, etc.).
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#### Security
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LXC provides a great deal of security out of the box in that it's separate from the system.
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Piston takes additional steps to make it resistant to
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various privilege escalation, denial-of-service, and resource saturation threats. These steps include:
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- Disabling outgoing network interaction
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- Capping max processes at 64 (resists `:(){ :|: &}:;`, `while True: os.fork()`, etc.)
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- Capping max files at 2048 (resists various file based attacks)
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- Mounting all resources read-only (resists `sudo rm -rf --no-preserve-root /`)
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- Running as a variety of unprivileged users
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- Capping runtime execution at 3 seconds
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- Capping stdout to 65536 characters (resists yes/no bombs and runaway output)
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- SIGKILLing misbehaving code
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#### License
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Piston is licensed under the MIT license.
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