1.1 KiB
Proof-of-concept custom loaders in Linux
This is a proof-of-concept to show different methods to load executables in the Linux kernel with our own loaders / linkers / interpreters.
Methods
1. binfmt_misc
We use a kernel module called binfmt_misc to register our own binary format in the Linux kernel.
The loader will be called in userspace.
See: https://www.kernel.org/doc/Documentation/binfmt_misc.txt
See: demo_binfmt_misc in Makefile
2. ELF Interpreter section (INTERP)
Every dynamically linked ELF executable contains a special section called .interp.
In case the Linux kernel sees such a section, I will load the interpreter instead. Afterwards, it is the task of the interpreter (usually ld-linux.so) to load all dependencies and do the final relocation.
See: demo_interpreter in the Makefile
3. Custom kernel module
We use the binfmt subsystem of the Linux kernel to implement our own format.
A good example is the loader for the script she-bangs (#!/bin/bash et al):
https://github.com/torvalds/linux/blob/master/fs/binfmt_script.c
Credits
Steffen Vogel post@steffenvogel.de