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Documentation: brief introduction and installation steps

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dump_stack() 2019-08-17 00:33:50 +00:00
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out-of-tree
===========
out-of-tree kernel {module, exploit} development tool
*out-of-tree* is the kernel {module, exploit} development tool.
*out-of-tree* was created on the purpose of decreasing complexity of
environment for developing, testing and debugging Linux kernel
exploits and out-of-tree kernel modules (that's why tool got a name
"out-of-tree").
While I'm trying to keep that documentation up-to-date, there may be
some missing information. Use ``out-of-tree --help-long`` for checking
all features.
If you found anything missed here, please make a pull request or send
patches to patch@dumpstack.io.
If you need personal support, your company is interested in the
project or you just want to share some thoughts -- feel free to write
to root@dumpstack.io.
Contents
========
:ref:`Keyword Index <genindex>`
.. toctree::
introduction.rst
installation.rst

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Installation
============
OS/Distro-specific
==================
Ubuntu
------
Install dependencies::
$ sudo snap install go --classic
$ sudo snap install docker
$ sudo apt install qemu-system-x86 build-essential gdb
macOS
-----
Install dependencies::
$ brew install go qemu
$ brew cask install docker
NixOS
-----
There's a minimal configuration that you need to apply::
#!nix
{ config, pkgs, ... }:
{
virtualisation.docker.enable = true;
virtualisation.libvirtd.enable = true;
environment.systemPackages = with pkgs; [
go git
];
}
Common
======
Setup Go environment::
$ echo 'export GOPATH=$HOME' >> ~/.bashrc
$ echo 'export PATH=$PATH:$HOME/bin' >> ~/.bashrc
$ source ~/.bashrc
Build *out-of-tree*::
$ go get -u code.dumpstack.io/tools/out-of-tree
.. note::
On a GNU/Linux you need to add your user to docker group if you want
to use *out-of-tree* without sudo. Note that this has a **serious**
security implications. Check *Docker* documentation for more
information.
Bootstrap::
$ out-of-tree bootstrap
Test that everything works::
$ cd $GOPATH/src/code.dumpstack.io/tools/out-of-tree/examples/kernel-exploit
$ out-of-tree kernel autogen --max=1
$ out-of-tree pew --max=1
Enjoy!

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Introduction
============
*out-of-tree* is written in *Go*, it uses *Docker* for generating
kernel/filesystem images and *Qemu* for virtualization.
Also it possible to generate kernels from the host system and use the
custom one.
*out-of-tree* supports *GNU/Linux* (usually it's tested on NixOS and
latest Ubuntu LTS) and *macOS*. Technically all systems that supported
by Go, Docker, and Qemu must work well. Create the issue if you'll
notice any issue in integration for your operating system.
All *Qemu* interaction is stateless.
*out-of-tree* is allow and require metadata (``.out-of-tree.toml``)
for work. TOML (Tom's Obvious, Minimal Language) is used for kernel
module/exploit description.
``.out-of-tree.toml`` is mandatory, you need to have in the current
directory (usually, it's a project of kernel module/exploit) or use
the ``--path`` flag.
Files
-----
All data is stored in ``~/.out-of-tree/``.
- *db.sqlite* contains logs related to run with ``out-of-tree pew``,
debug mode (``out-of-tree debug``) is not store any data.
- *images* used for filesystem images (rootfs images that used for
``qemu -hda ...``) that can be generated with the
``tools/qemu-*-img/...``.
- *kernels* stores all kernel ``vmlinuz/initrd/config/...`` files that
generated previously with a some *Docker magic*.
- *kernels.toml* contains metadata for generated kernels. It's not
supposed to be edited by hands.
- *kernels.user.toml* is default path for custom kernels definition.
- *Ubuntu* (or *Centos*/*Debian*/...) is the Dockerfiles tree
(DistroName/DistroVersion/Dockerfile). Each Dockerfile contains a
base layer and incrementally updated list of kernels that must be
installed.
Overview
---------
*out-of-tree* creating debugging environment based on **defined** kernels::
$ out-of-tree debug --kernel 'Ubuntu:4.15.0-58-generic'
[*] KASLR SMEP SMAP
[*] gdb runned on tcp::1234
[*] build result copied to /tmp/exploit
ssh -o StrictHostKeyChecking=no -p 29308 root@127.133.45.236
gdb /usr/lib/debug/boot/vmlinux-4.15.0-58-generic -ex 'target remote tcp::1234'
out-of-tree> help
help : print this help message
log : print qemu log
clog : print qemu log and cleanup buffer
cleanup : cleanup qemu log buffer
ssh : print arguments to ssh command
quit : quit
out-of-tree>
*out-of-tree* uses three stages for automated runs:
- Build
- Inside the docker container (default).
- Binary version (de facto skip stage).
- On host.
- Run
- Insmod for the kernel module.
- This step is skipped for exploits.
- Test
- Run the test.sh script on the target machine.
- Test script is run from *root* for the kernel module.
- Test script is run from *user* for the kernel exploit.
- Test script for the kernel module is fully custom (only return
value is checked).
- Test script for the kernel exploit receives two parameters:
- Path to exploit
- Path to file that must be created with root privileges.
Security
--------
*out-of-tree* is not supposed to be used on multi-user systems or with
an untrusted input.
Meanwhile, all modern hypervisors are supporting nested
virtualization, which means you can use it for isolating *out-of-tree*
if you want to work with an untrusted input (e.g. with a mass-scale
testing public proofs-of-concept).