AndroidNativeEmu

Allows you to partly emulate an Android native library.

This is an educational project to learn more about the ELF file format and Unicorn.

Read me for chinese readers 中文README

Features

• Emulation of the JNI Invocation API so JNI_OnLoad can be called properly.
• Emulation of native memory for malloc / memcpy.
• Emulation of syscalls (SVC #0) instruction.
• Hooking through the symbol table.
• All JavaVM, JNIEnv and hooked functions are handled by python.
• Enable VFP support.

Installation

You can install AndroidNativeEmu with pip.

pip install androidemu

TODO

• Improve file descriptors in vfs/file_system.py so they are re-useable.
• Add a way for the VirtualFileSystem to give back dynamic files, such as /proc/self/status, /proc/self/status but also /dev/urandom.
• Library consumers must be able to easily rebuild the needed Java classes for a native library, which are used by the native library through the JNIEnv.
  • Classes
  • Objects
  • Methods
  • Native methods
  • Fields
  • Types
  • Reflection

Dependencies

• Unicorn CPU emulator framework
• Keystone assembler framework

Resources

All resources used while developing AndroidNativeEmu.

Text sources

• https://greek0.net/elf.html
• https://stackoverflow.com/questions/13908276/loading-elf-file-in-c-in-user-space
• https://programtalk.com/python-examples/pyelftools.elftools.elf.relocation.Relocation/
• http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044f/IHI0044F_aaelf.pdf
• https://wiki.osdev.org/ELF_Tutorial
• https://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/functions.html
• https://android.googlesource.com/platform/dalvik/+/donut-release/vm/Jni.c

Code sources

• https://github.com/lunixbochs/usercorn
• https://github.com/slick1015/pad_unpacker (SVC 0 instruction)