Compress the compiled C code in the stub on lx_exec86 (saves 157 bytes).
Also make 'fold_begin' processing more robust. p_lx_elf.cpp p_lx_sh.cpp p_unix.cpp stub/Makefile stub/l_lx_exec86.asm committer: jreiser <jreiser> 958923851 +0000
This commit is contained in:
John Reiser
+103
-37
@@ -1,10 +1,13 @@
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; l_lx_exec86.asm -- Linux program entry point & decompressor (execve)
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; l_lx_exec86.asm -- Linux program entry point & decompressor (kernel exec)
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;
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; This file is part of the UPX executable compressor.
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;
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; Copyright (C) 1996-2000 Markus Franz Xaver Johannes Oberhumer
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; Copyright (C) 1996-2000 Laszlo Molnar
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;
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; Integration of virtual exec() with decompression is
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; Copyright (C) 2000 John F. Reiser. All rights reserved.
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;
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; UPX and the UCL library are free software; you can redistribute them
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; and/or modify them under the terms of the GNU General Public License as
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; published by the Free Software Foundation; either version 2 of
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@@ -23,6 +26,8 @@
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; Markus F.X.J. Oberhumer Laszlo Molnar
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; markus.oberhumer@jk.uni-linz.ac.at ml1050@cdata.tvnet.hu
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;
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; John F. Reiser
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; jreiser@BitWagon.com
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BITS 32
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@@ -48,8 +53,8 @@
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%endif
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%include "ident.ash"
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%include "ident.ash"
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; /*************************************************************************
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; // program entry point
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@@ -57,28 +62,45 @@
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; **************************************************************************/
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GLOBAL _start
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EXTERN upx_main
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_start:
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call main ; push &decompress
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;;;; int3
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;; How to debug this code: Uncomment the 'int3' breakpoint instruction above.
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;; Build the stubs and upx. Compress a testcase, such as a copy of /bin/date.
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;; Invoke gdb, and give a 'run' command. Define a single-step macro such as
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;; define g
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;; stepi
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;; x/i $pc
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;; end
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;; and a step-over macro such as
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;; define h
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;; x/2i $pc
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;; tbreak *$_
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;; continue
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;; x/i $pc
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;; end
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;; Step through the code; remember that <Enter> repeats the previous command.
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;;
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%if 0
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; personality(PER_LINUX)
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mov eax, 136 ; syscall_personality
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xor ebx, ebx ; PER_LINUX
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int 0x80
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%endif
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call main ; push address of decompress subroutine
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; /*************************************************************************
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; // C callable decompressor
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; **************************************************************************/
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%define INP dword [esp+24+4]
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%define INS dword [esp+24+8]
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%define OUTP dword [esp+24+12]
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%define OUTS dword [esp+24+16]
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%define INP dword [esp+8*4+4]
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%define INS dword [esp+8*4+8]
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%define OUTP dword [esp+8*4+12]
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%define OUTS dword [esp+8*4+16]
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decompress:
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push ebp
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push edi
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push esi
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push ebx
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push ecx
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push edx
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cld
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pusha
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; cld
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mov esi, INP
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mov edi, OUTP
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@@ -110,36 +132,80 @@ decompress:
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mov edx, OUTS
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mov [edx], edi
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pop edx
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pop ecx
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pop ebx
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pop esi
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pop edi
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pop ebp
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mov [7*4 + esp], eax
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popa
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ret
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; /*************************************************************************
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; // prepare arguments and call upx_main
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; **************************************************************************/
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%define PAGE_MASK (~0<<12)
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%define PAGE_SIZE ( 1<<12)
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%define szElf32_Ehdr 0x34
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%define szElf32_Phdr 8*4
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%define p_filesz 4*4
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%define p_memsz 5*4
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%define a_val 4
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%define MAP_FIXED 0x10
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%define MAP_PRIVATE 0x02
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%define MAP_ANONYMOUS 0x20
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%define PROT_READ 1
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%define PROT_WRITE 2
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%define PROT_EXEC 4
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%define __NR_mmap 90
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%define __NR_munmap 91
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; Decompress the rest of this loader, and jump to it
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unfold:
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pop esi ; &fold_begin = src
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push esi ; &dst
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mov ecx, ebp ; &decompress
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and ecx, dword PAGE_MASK ; &my_elfhdr
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mov ebx, ecx ; save &my_elfhdr for later
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;; Compressed code now begins at fold_begin.
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;; We want decompressed code to begin at fold_begin, too.
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;; Move the compressed code to the high end of the page.
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;; Assume non-overlapping so that forward movsb is OK.
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lea edi, [-PAGE_MASK + ecx] ; high end of page
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add ecx, [p_filesz + szElf32_Ehdr + ecx] ; beyond src
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sub ecx, esi ; srclen
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push ecx ; srclen
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sub edi, ecx
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push edi ; &src
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cld
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rep movsb
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call ebp ; decompress(&src, srclen, &dst, &dstlen)
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pop eax ; discard &src
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pop eax ; discard srclen
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pop eax ; &dst == fold_begin
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;; icache lookahead of compressed code after "call unfold" is still there.
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;; Synchronize with dcache of decompressed code.
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pushf
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push cs
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push eax
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iret ; back to fold_begin!
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main:
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pop ebp ; &decompress
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%if 0
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; personality(PER_LINUX)
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mov eax, 136 ; syscall_personality
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xor ebx, ebx ; PER_LINUX
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int 0x80
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%endif
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pop ebp ; &decompress
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push eax ; place to store dstlen
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push esp ; &dstlen
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call unfold
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fold_begin: ;; this label is known to the Makefile
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pop eax ; discard &dstlen
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pop eax ; discard dstlen
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pop eax ; Pop the argument count
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mov ecx, esp ; argv starts just at the current stack top
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lea edx, [ecx+eax*4+4] ; envp = &argv[argc + 1]
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push eax ; Restore the stack
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push ebp ; argument: &decompress
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%define PAGE_MASK (~0<<12)
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and ebp, PAGE_MASK
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push ebp ; argument: &Elf32_Ehdr
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push edx ; Push third argument: envp
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push ecx ; Push second argument: argv
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;;; push eax ; Push first argument: argc
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push ebx ; argument: &my_elfhdr
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push edx ; argument: envp
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push ecx ; argument: argv
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EXTERN upx_main
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call upx_main ; Call the UPX main function
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hlt ; Crash if somehow upx_main does return
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