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Linux i386 allow compression of position-independent main executables (gcc -pie).

Browse Source 
p_elf.h p_lx_elf.cpp p_lx_elf.h p_lx_exc.cpp
	stub/fold_elf86.asm stub/fold_elf86.h stub/l_lx_elf.c
	stub/l_lx_elf86.asm stub/l_lx_elf86.h stub/l_lx_elf86.lds
	stub/linux.hh

committer: jreiser <jreiser> 1126886896 +0000
This commit is contained in:
John Reiser
2005-09-16 16:08:16 +00:00
parent eb6c51426a
commit 3f7b642c7d
11 changed files with 761 additions and 515 deletions
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src/stub/l_lx_elf86.asm
+26 -20
View File
@@ -45,7 +45,7 @@
GLOBAL _start
;__LEXEC000__
_start:
;;;; int3
int3
;; How to debug this code: Uncomment the 'int3' breakpoint instruction above.
;; Build the stubs and upx. Compress a testcase, such as a copy of /bin/date.
;; Invoke gdb, and give a 'run' command. Define a single-step macro such as
@@ -133,41 +133,47 @@ decompress:
%define PROT_WRITE 2
%define PROT_EXEC 4
%define __NR_mmap 90
%define szElf32_Ehdr 0x34
%define p_memsz 5*4
; Decompress the rest of this loader, and jump to it
unfold:
pop esi ; &{ sz_uncompressed, sz_compressed, compressed_data...}
cld
lodsd
push eax ; sz_uncompressed (junk, actually)
push esp ; &sz_uncompressed
mov eax, 0x1000000
push eax ; &destination
pop esi ; &{ b_info:{sz_unc, sz_cpr, 4{byte}}, compressed_data...}
; mmap a page to hold the decompressed program
xor ecx, ecx
push ecx
push ecx
mov ch, PAGE_SIZE >> 8
lea eax, [ebp - (4+ decompress - _start)] ; 4: sizeof(int)
sub eax, [eax] ; %eax= &Elf32_Ehdr of this program
mov edx, eax ; %edx= &Elf32_Ehdr of this program
add eax, [p_memsz + szElf32_Ehdr + eax] ; page after .text
push eax ; destination for 'ret'
; mmap a page to hold the decompressed fold_elf86
xor ecx, ecx ; %ecx= 0
; MAP_ANONYMOUS ==>offset is ignored, so do not push!
; push ecx ; offset
push ecx ; fd must be in valid range, but then ignored
push byte MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS
mov ch, PAGE_SIZE >> 8 ; %ecx= PAGE_SIZE
push byte PROT_READ | PROT_WRITE | PROT_EXEC
push ecx ; length
push eax ; destination
mov ebx, esp ; address of parameter vector for __NR_mmap
push byte __NR_mmap
pop eax
int 0x80
xchg eax, ebx
mov bh, PAGE_SIZE>>8 ; ebx= 0x1001000
add esp, byte 6*4 ; discard args to mmap
int 0x80 ; changes only %eax; %edx is live
xchg eax, edx ; %edx= page after .text; %eax= &Elf32_Ehdr of this program
xchg eax, ebx ; %ebx= &Elf32_Ehdr of this program
cld
lodsd
push eax ; sz_uncompressed (junk, actually)
push esp ; &dstlen
push edx ; &dst
lodsd
push eax ; sz_compressed
lodsd ; junk cto8, algo, unused[2]
lodsd ; last 4 bytes of b_info
push esi ; &compressed_data
call ebp ; decompress(&src, srclen, &dst, &dstlen)
pop eax ; discard &compressed_data
pop eax ; discard sz_compressed
add esp, byte (4+1 + 6-1)*4 ; (4+1) args to decompress, (6-1) args to mmap
ret ; &destination
main:
pop ebp ; &decompress