Asm
From Ggl's wiki
Asm
- Static Elf32 binary template in nasm syntax :
BITS 32 org 0x08048000
; Elf32_Ehdr ehdr: db 0x7F, "ELF", 1, 1, 1 ; e_ident times 9 db 0 dw 2 ; e_type dw 3 ; e_machine dd 1 ; e_version dd _start ; e_entry dd phdr - $$ ; e_phoff dd 0 ; e_shoff dd 0 ; e_flags dw ehdrsize ; e_ehsize dw phdrsize ; e_phentsize dw 1 ; e_phnum dw 0 ; e_shentsize dw 0 ; e_shnum dw 0 ; e_shstrndx ehdrsize equ $ - ehdr
; Elf32_Phdr phdr: dd 1 ; p_type dd 0 ; p_offset dd $$ ; p_vaddr dd $$ ; p_paddr dd filesize ; p_filesz dd filesize ; p_memsz dd 5 ; p_flags dd 0x1000 ; p_align phdrsize equ $ - phdr filesize equ $ - $$
Compile with nasm or yasm '-f bin' option. The compiled binary won't have any section.
Above is a example of such a binary :
$ readelf -a elfraw
ELF Header: Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 Class: ELF32 Data: 2's complement, little endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: EXEC (Executable file) Machine: Intel 80386 Version: 0x1 Entry point address: 0x80480b7 Start of program headers: 52 (bytes into file) Start of section headers: 0 (bytes into file) Flags: 0x0 Size of this header: 52 (bytes) Size of program headers: 32 (bytes) Number of program headers: 1 Size of section headers: 0 (bytes) Number of section headers: 0 Section header string table index: 0
There are no sections in this file. There are no sections in this file.
Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align LOAD 0x000000 0x08048000 0x08048000 0x00200 0x00200 R E 0x1000
There is no dynamic section in this file. There are no relocations in this file. There are no unwind sections in this file. No version information found in this file.
- Linux dynamic linking
With nasm syntax, you can use the keyword extern to link with external libraries.
