Remill

Remill is a static binary translator that translates machine code instructions into LLVM bitcode. It translates AArch64 (64-bit ARMv8), SPARC32 (SPARCv8), SPARC64 (SPARCv9), x86 and amd64 machine code (including AVX and AVX512) into LLVM bitcode. AArch32 (32-bit ARMv8 / ARMv7) support is underway.

Remill focuses on accurately lifting instructions. It is meant to be used as a library for other tools, e.g. McSema.

Build Status

Additional Documentation

• How to contribute
• How to implement the semantics of an instruction
• How instructions are lifted
• The design and architecture of Remill

Getting Help

If you are experiencing undocumented problems with Remill then ask for help in the #binary-lifting channel of the Empire Hacking Slack.

Supported Platforms

Remill is supported on Linux platforms and has been tested on Ubuntu 20.04. Remill also works on macOS, and has experimental support for Windows.

Remill's Linux version can also be built via Docker for quicker testing.

Dependencies

Most of Remill's dependencies can be provided by the cxx-common repository. Trail of Bits hosts downloadable, pre-built versions of cxx-common, which makes it substantially easier to get up and running with Remill. Nonetheless, the following table represents most of Remill's dependencies.

Name	Version
Git	Latest
CMake	3.14+
Google Flags	Latest
Google Log	Latest
Google Test	Latest
LLVM	12
Clang	12
Intel XED	Latest
Python	2.7
Unzip	Latest
ccache	Latest

Getting and Building the Code

Docker Build

Remill now comes with a Dockerfile for easier testing. This Dockerfile references the cxx-common container to have all pre-requisite libraries available.

The Dockerfile allows for quick builds of multiple supported LLVM, architecture, and Linux configurations.

Quickstart (builds Remill against LLVM 12 on Ubuntu 20.04 for AMD64):

Clone Remill:

#Clone the repository.
git clone https://github.com/lifting-bits/remill.git
cd remill

Build Remill Docker container:

# do the build
docker build . -t remill \
     -f Dockerfile \
     --build-arg UBUNTU_VERSION=20.04 \
     --build-arg ARCH=amd64 \
     --build-arg LLVM_VERSION=12

Ensure remill works:

# Decode some AMD64 instructions to LLVM
docker run --rm -it remill \
     --arch amd64 --ir_out /dev/stdout --bytes c704ba01000000
     
# Decode some AArch64 instructions to LLVM
docker run --rm -it remill \
     --arch aarch64 --address 0x400544 --ir_out /dev/stdout \
     --bytes FD7BBFA90000009000601891FD030091B7FFFF97E0031F2AFD7BC1A8C0035FD6

On Linux

First, update aptitude and get install the baseline dependencies.

sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get upgrade

sudo apt-get install \
     git \
     python3 \
     wget \
     curl \
     build-essential \
     lsb-release \
     ccache \
     libc6-dev:i386 \
     'libstdc++-*-dev:i386' \
     g++-multilib

Next, clone the repository. This will clone the code into the remill directory.

git clone https://github.com/lifting-bits/remill.git

Next, we build Remill. This script will create another directory, remill-build, in the current working directory. All remaining dependencies needed by Remill will be built in the remill-build directory.

./remill/scripts/build.sh

Next, we can install Remill. Remill itself is a library, and so there is no real way to try it. However, you can head on over to the McSema repository, which uses Remill for lifting instructions.

cd ./remill-build
sudo make install

We can also build and run Remill's test suite.

cd ./remill-build
make test_dependencies
make test

Full Source Builds

Sometimes, you want to build everything from source, including the cxx-common libraries remill depends on. To build against a custom cxx-common location, you can use the following cmake invocation:

mkdir build
cd build
cmake  \
  -DCMAKE_INSTALL_PREFIX="<path where remill will install>" \
  -DVCPKG_ROOT="<path to cxx-common directory>/vcpkg"  \
  -G Ninja  \
  ..
cmake --build .
cmake --build . --target install

The output may produce some CMake warnings about policy CMP0003. These warnings are safe to ignore.

Common Build Issues

If you see errors similar to the following:

fatal error: 'bits/c++config.h' file not found

Then you need to install 32-bit libstdc++ headers and libraries. On a Debian/Ubuntu based distribution, You would want to do something like this:

sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get install libc6-dev:i386 libstdc++-10-dev:i386 g++-multilib

This error happens because the SPARC32 runtime semantics (the bitcode library which lives in <install directory>/share/remill/<version>/semantics/sparc32.bc) are built as 32-bit code, but 32-bit development libraries are not installed by default.

A similar situation occurs when building remill on arm64 Linux. In that case, you want to follow a similar workflow, except the architecture used in dpkg and apt-get commands would be armhf instead of i386.

Another alternative is to disable SPARC32 runtime semantics. To do that, use the -DREMILL_BUILD_SPARC32_RUNTIME=False option when invoking cmake.