loader/README.md

ELF Loader

A minimal user-space ELF loader for Linux.

This project is an experiment in implementing a user-space execve. It can load and execute Linux ELF binaries by mapping their segments into memory, setting up the stack, and trampolining to their entry point.

Features

It supports statically linked PIE(ET_DYN) and non-PIE(ET_ECEC) executables directly.

For dynamically linked executables it loads the in PT_INTERP specified interpreter and transfers control to it, such that it handles the full dynamic linkign process.

It also sanitizes the stack by removing the loader's arguments and updates auxv with the client's information.

Building and Running

This creates the loader executable and a set of test binaries in zig-out/bin/ :

zig build

Alternatively use something like this to run directly:

zig build run -- /bin/ls
# or
zig build run -- ls

This runs the tests:

zig build test

You can run an executable by passing it as an argument to the loader. Any subsequent arguments are passed through to the target executable.

# Run a test executable through the loader
./zig-out/bin/loader ./zig-out/bin/test_nolibc_pie_helloWorld
# Output: Hello World!

# Run a test executable that prints its arguments
./zig-out/bin/loader ./zig-out/bin/test_nolibc_pie_printArgs foo bar baz
# Output: ./zig-out/bin/test_nolibc_pie_printArgs foo bar baz

# Run echo
./zig-out/bin/loader echo Hello There
# Output: Hello There

License

Apache 2.0