gdylib

README

gdylib

Module providing adding following load commands:

• LC_LOAD_DYLIB
• LC_LOAD_WEAK_DYLIB
• LC_RPATH

Adding loads can be accomplished with keeping the old signature or removal of it. Module will check whether there is enough space for the new load and return ErrNotEnoughSpace if there is not enough.

This module is heavily inspired/guided by insert_dylib, install_name_tool projects.

It supports 32bit and 64bit architectures with assumed little endian. FAT binaries are not yet supported.

Usage

package main

import (
	"github.com/lateralusd/gdylib"
	"io"
	"os"
)

func main() {
	r, err := gdylib.Run(os.Args[1], os.Args[2],
		gdylib.WithLoadType(gdylib.WEAK),
		gdylib.WithRemoveCodeSig(true))
	if err != nil {
		panic(err)
	}

	nf, err := os.Create(os.Args[3])
	if err != nil {
		panic(err)
	}
	defer nf.Close()

	io.Copy(nf, r)
}

$ go run main.go a.out @executable_path/FridaGadget.dylib new_file
$ otool -l new_file | tail
 datasize 0
Load command 16
          cmd LC_LOAD_WEAK_DYLIB
      cmdsize 64
         name @executable_path/FridaGadget.dylib (offset 24)
   time stamp 0 Thu Jan  1 01:00:00 1970
      current version 0.0.0
compatibility version 0.0.0

Documentation

Index

• Variables
• func Run(binaryPath, dylibPath string, opts ...Option) (io.Reader, error)
• type LoadType
• type Option
  • func WithLoadType(t LoadType) Option
  • func WithRemoveCodeSig(remove bool) Option

Variables

var (
	ErrFileNotSupported = errors.New("file not supported")
	ErrNotExecute       = errors.New("not executable (MH_EXECUTE)")
	ErrNotLastCommand   = errors.New("cmd LC_CODE_SIGNATURE not last")
	ErrTypeNotSupported = errors.New("unsupported load type")
	ErrNotEnoughSpace   = errors.New("not enough space for new command")
)

Functions

func Run

func Run(binaryPath, dylibPath string, opts ...Option) (io.Reader, error)

Types

type LoadType

type LoadType uint32

const (
	WEAK LoadType = iota
	DYLIB
	RPATH
)

type Option

type Option = func(c *config)

func WithLoadType

func WithLoadType(t LoadType) Option

func WithRemoveCodeSig

func WithRemoveCodeSig(remove bool) Option