ELF x86-64 Linux Executable by hand

Generate an ELF 64-bit executable by hand. This is an example of how to manually create an ELF 64 executable for linux that will print out some string and then exit using sys_write and sys_exit linus system calls.

It will generate the ELF header, then 2 Program Headers (one for the .text segment and one for the .data segment). Then the .text segment and .data segment are outputted to the binary.

The .text segment will do a sys_write using the data offset from where the .data segment is located and then it will do a sys_exit.

The .data segment contains just the string data.

This doesn't currently do back-patching. The data segment is always known since the ELF header and text segment aren't changing. This needs to be fixed, but I don't know a good way to do it.

$ go run main.go
wrote binary to tiny-x64
$ ./tiny-x64
Hello World, this is my tiny executable
$ ls -hal ./tiny-x64
-rwxr-xr-x 1 vishen vishen 257 Jun 21 08:58 ./tiny-x64*

# Or run with a desired string to output in the binary
$ go run main.go -output hello-world -word "Hello, World!"
wrote binary to hello-world
$ ./hello-world
Hello, World!
$ ls -hal ./hello-world
-rwxr-xr-x 1 vishen vishen 231 Jun 21 08:59 ./hello-world*

Resources

• https://en.wikipedia.org/wiki/Executable_and_Linkable_Format
• https://www.hanshq.net/making-executables.html#linux
• https://github.com/nivertech/erl_elf_test/blob/master/manually_creating_elf_executable.md
• http://www.sco.com/developers/gabi/latest/ch5.pheader.html