m-1-k-3 / firmae_kernel-v4.1

kernel-v4.1 for firmadyne mips

Introduction

This contains the modified MIPS kernel for the FIRMADYNE framework, which includes an in-tree firmadyne module to perform instrumentation and emulation.

This module can be configured using the following parameters:

Parameter	Default	Values	Description
devfs	1 (on)	0, 1	Create stubs in devfs and emulate behavior
execute	1 (on)	0 - 5	Counter to execute /firmadyne/console after 4th execve() syscall (requires syscall hooks), 0 to disable
reboot	1 (on)	0, 1	Attempt to emulate system reboot by re-executing /sbin/init
procfs	1 (on)	0, 1	Create stubs in procfs and emulate behavior
syscall	255 (all)	0 - 16	Output log bitmask for hooking system calls using the kprobe framework, 0 to disable

Usage

Since MIPS systems can be either big-endian or little-endian, this kernel should be compiled for both endianness. The below instructions produce a little- endian (mipsel) kernel, but should be repeated for a big-endian (mipseb) kernel.

Little-Endian (MIPSEL)

Create the kernel build output directory:

mkdir -p build/mipsel

Copy the configuration file into the build directory:

cp config.mipsel build/mipsel/.config

Assuming that the appropriate cross-compiler is installed in /opt/cross/mipsel-linux-musl, execute:

make ARCH=mips CROSS_COMPILE=/opt/cross/mipsel-linux-musl/bin/mipsel-linux-musl- O=./build/mipsel -j8

The output kernel image will be generated at the following location:

build/mipsel/vmlinux

Big-Endian (MIPSEB)

Create the kernel build output directory:

mkdir -p build/mipseb

Copy the configuration file into the build directory:

cp config.mipseb build/mipseb/.config

Assuming that the appropriate cross-compiler is installed in /opt/cross/mipseb-linux-musl, execute:

make ARCH=mips CROSS_COMPILE=/opt/cross/mipseb-linux-musl/bin/mipseb-linux-musl- O=./build/mipseb -j8

The output kernel image will be generated at the following location:

build/mipseb/vmlinux

Notes

This instrumented MIPS kernel is built for the ARCH_MALTA MIPS Malta target with a 24kf processor. As a result, hardware support on this emulated target is limited to peripherals that are both available on the emulated target and supported by QEMU. Since an emulated PCI bus is available and supported, this allows additional ethernet devices (e.g. rtl8139, smc91c111, pcnet32, etc.) to be attached to the virtualized system. Emulated hard drives can be attached using the IDE block device interface.

As future work, it may be useful to switch to VirtIO on MIPS, since support has been recently merged into the Linux kernel. However, this would require a kernel upgrade. Additionally, it may be useful to add support for MIPS64 systems, although these do not appear to be prevalent. Nevertheless, at the time, we performed our published experiments over our dataset using this kernel for MIPS systems.

Pull requests are greatly appreciated!