mirror of
https://github.com/alliedmodders/amxmodx.git
synced 2024-10-17 15:56:52 +03:00
420 lines
9.0 KiB
C
420 lines
9.0 KiB
C
#include "asm.h"
|
|
|
|
#ifndef WIN32
|
|
#define _GNU_SOURCE
|
|
#include <dlfcn.h>
|
|
#include <string.h>
|
|
|
|
#define REG_EAX 0
|
|
#define REG_ECX 1
|
|
#define REG_EDX 2
|
|
#define REG_EBX 3
|
|
|
|
#define IA32_MOV_REG_IMM 0xB8 // encoding is +r <imm32>
|
|
#endif
|
|
|
|
/**
|
|
* Checks if a call to a fpic thunk has just been written into dest.
|
|
* If found replaces it with a direct mov that sets the required register to the value of pc.
|
|
*
|
|
* @param dest Destination buffer where a call opcode + addr (5 bytes) has just been written.
|
|
* @param pc The program counter value that needs to be set (usually the next address from the source).
|
|
* @noreturn
|
|
*/
|
|
void check_thunks(unsigned char *dest, unsigned char *pc)
|
|
{
|
|
#if defined WIN32
|
|
return;
|
|
#else
|
|
/* Step write address back 4 to the start of the function address */
|
|
unsigned char *writeaddr = dest - 4;
|
|
unsigned char *calloffset = *(unsigned char **)writeaddr;
|
|
unsigned char *calladdr = (unsigned char *)(dest + (unsigned int)calloffset);
|
|
|
|
/* Lookup name of function being called */
|
|
if ((*calladdr == 0x8B) && (*(calladdr+2) == 0x24) && (*(calladdr+3) == 0xC3))
|
|
{
|
|
//a thunk maybe?
|
|
char movByte = IA32_MOV_REG_IMM;
|
|
|
|
/* Calculate the correct mov opcode */
|
|
switch (*(calladdr+1))
|
|
{
|
|
case 0x04:
|
|
{
|
|
movByte += REG_EAX;
|
|
break;
|
|
}
|
|
case 0x1C:
|
|
{
|
|
movByte += REG_EBX;
|
|
break;
|
|
}
|
|
case 0x0C:
|
|
{
|
|
movByte += REG_ECX;
|
|
break;
|
|
}
|
|
case 0x14:
|
|
{
|
|
movByte += REG_EDX;
|
|
break;
|
|
}
|
|
default:
|
|
{
|
|
//Msg("Unknown thunk: %c\n", *(calladdr+1));
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Move our write address back one to where the call opcode was */
|
|
writeaddr--;
|
|
|
|
|
|
/* Write our mov */
|
|
*writeaddr = movByte;
|
|
writeaddr++;
|
|
|
|
/* Write the value - The provided program counter value */
|
|
*(void **)writeaddr = (void *)pc;
|
|
writeaddr += 4;
|
|
}
|
|
|
|
return;
|
|
#endif
|
|
}
|
|
|
|
//if dest is NULL, returns minimum number of bytes needed to be copied
|
|
//if dest is not NULL, it will copy the bytes to dest as well as fix CALLs and JMPs
|
|
//http://www.devmaster.net/forums/showthread.php?t=2311
|
|
int copy_bytes(unsigned char *func, unsigned char* dest, int required_len) {
|
|
int bytecount = 0;
|
|
|
|
while(bytecount < required_len && *func != 0xCC)
|
|
{
|
|
// prefixes F0h, F2h, F3h, 66h, 67h, D8h-DFh, 2Eh, 36h, 3Eh, 26h, 64h and 65h
|
|
int operandSize = 4;
|
|
int FPU = 0;
|
|
int twoByte = 0;
|
|
unsigned char opcode = 0x90;
|
|
unsigned char modRM = 0xFF;
|
|
while(*func == 0xF0 ||
|
|
*func == 0xF2 ||
|
|
*func == 0xF3 ||
|
|
(*func & 0xFC) == 0x64 ||
|
|
(*func & 0xF8) == 0xD8 ||
|
|
(*func & 0x7E) == 0x62)
|
|
{
|
|
if(*func == 0x66)
|
|
{
|
|
operandSize = 2;
|
|
}
|
|
else if((*func & 0xF8) == 0xD8)
|
|
{
|
|
FPU = *func;
|
|
if (dest)
|
|
*dest++ = *func++;
|
|
else
|
|
func++;
|
|
bytecount++;
|
|
break;
|
|
}
|
|
|
|
if (dest)
|
|
*dest++ = *func++;
|
|
else
|
|
func++;
|
|
bytecount++;
|
|
}
|
|
|
|
// two-byte opcode byte
|
|
if(*func == 0x0F)
|
|
{
|
|
twoByte = 1;
|
|
if (dest)
|
|
*dest++ = *func++;
|
|
else
|
|
func++;
|
|
bytecount++;
|
|
}
|
|
|
|
// opcode byte
|
|
opcode = *func++;
|
|
if (dest) *dest++ = opcode;
|
|
bytecount++;
|
|
|
|
// mod R/M byte
|
|
modRM = 0xFF;
|
|
if(FPU)
|
|
{
|
|
if((opcode & 0xC0) != 0xC0)
|
|
{
|
|
modRM = opcode;
|
|
}
|
|
}
|
|
else if(!twoByte)
|
|
{
|
|
if((opcode & 0xC4) == 0x00 ||
|
|
((opcode & 0xF4) == 0x60 && ((opcode & 0x0A) == 0x02 || (opcode & 0x09) == 0x09)) ||
|
|
(opcode & 0xF0) == 0x80 ||
|
|
((opcode & 0xF8) == 0xC0 && (opcode & 0x0E) != 0x02) ||
|
|
(opcode & 0xFC) == 0xD0 ||
|
|
(opcode & 0xF6) == 0xF6)
|
|
{
|
|
modRM = *func++;
|
|
if (dest) *dest++ = modRM;
|
|
bytecount++;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if(((opcode & 0xF0) == 0x00 && (opcode & 0x0F) >= 0x04 && (opcode & 0x0D) != 0x0D) ||
|
|
(opcode & 0xF0) == 0x30 ||
|
|
opcode == 0x77 ||
|
|
(opcode & 0xF0) == 0x80 ||
|
|
((opcode & 0xF0) == 0xA0 && (opcode & 0x07) <= 0x02) ||
|
|
(opcode & 0xF8) == 0xC8)
|
|
{
|
|
// No mod R/M byte
|
|
}
|
|
else
|
|
{
|
|
modRM = *func++;
|
|
if (dest) *dest++ = modRM;
|
|
bytecount++;
|
|
}
|
|
}
|
|
|
|
// SIB
|
|
if((modRM & 0x07) == 0x04 &&
|
|
(modRM & 0xC0) != 0xC0)
|
|
{
|
|
if (dest)
|
|
*dest++ = *func++; //SIB
|
|
else
|
|
func++;
|
|
bytecount++;
|
|
}
|
|
|
|
// mod R/M displacement
|
|
|
|
// Dword displacement, no base
|
|
if((modRM & 0xC5) == 0x05) {
|
|
if (dest) {
|
|
*(unsigned int*)dest = *(unsigned int*)func;
|
|
dest += 4;
|
|
}
|
|
func += 4;
|
|
bytecount += 4;
|
|
}
|
|
|
|
// Byte displacement
|
|
if((modRM & 0xC0) == 0x40) {
|
|
if (dest)
|
|
*dest++ = *func++;
|
|
else
|
|
func++;
|
|
bytecount++;
|
|
}
|
|
|
|
// Dword displacement
|
|
if((modRM & 0xC0) == 0x80) {
|
|
if (dest) {
|
|
*(unsigned int*)dest = *(unsigned int*)func;
|
|
dest += 4;
|
|
}
|
|
func += 4;
|
|
bytecount += 4;
|
|
}
|
|
|
|
// immediate
|
|
if(FPU)
|
|
{
|
|
// Can't have immediate operand
|
|
}
|
|
else if(!twoByte)
|
|
{
|
|
if((opcode & 0xC7) == 0x04 ||
|
|
(opcode & 0xFE) == 0x6A || // PUSH/POP/IMUL
|
|
(opcode & 0xF0) == 0x70 || // Jcc
|
|
opcode == 0x80 ||
|
|
opcode == 0x83 ||
|
|
(opcode & 0xFD) == 0xA0 || // MOV
|
|
opcode == 0xA8 || // TEST
|
|
(opcode & 0xF8) == 0xB0 || // MOV
|
|
(opcode & 0xFE) == 0xC0 || // RCL
|
|
opcode == 0xC6 || // MOV
|
|
opcode == 0xCD || // INT
|
|
(opcode & 0xFE) == 0xD4 || // AAD/AAM
|
|
(opcode & 0xF8) == 0xE0 || // LOOP/JCXZ
|
|
opcode == 0xEB ||
|
|
(opcode == 0xF6 && (modRM & 0x30) == 0x00)) // TEST
|
|
{
|
|
if (dest)
|
|
*dest++ = *func++;
|
|
else
|
|
func++;
|
|
bytecount++;
|
|
}
|
|
else if((opcode & 0xF7) == 0xC2) // RET
|
|
{
|
|
if (dest) {
|
|
*(unsigned short*)dest = *(unsigned short*)func;
|
|
dest += 2;
|
|
}
|
|
func += 2;
|
|
bytecount += 2;
|
|
}
|
|
else if((opcode & 0xFC) == 0x80 ||
|
|
(opcode & 0xC7) == 0x05 ||
|
|
(opcode & 0xF8) == 0xB8 ||
|
|
(opcode & 0xFE) == 0xE8 || // CALL/Jcc
|
|
(opcode & 0xFE) == 0x68 ||
|
|
(opcode & 0xFC) == 0xA0 ||
|
|
(opcode & 0xEE) == 0xA8 ||
|
|
opcode == 0xC7 ||
|
|
(opcode == 0xF7 && (modRM & 0x30) == 0x00))
|
|
{
|
|
if (dest) {
|
|
//Fix CALL/JMP offset
|
|
if ((opcode & 0xFE) == 0xE8) {
|
|
if (operandSize == 4)
|
|
{
|
|
*(long*)dest = ((func + *(long*)func) - dest);
|
|
|
|
//pRED* edit. func is the current address of the call address, +4 is the next instruction, so the value of $pc
|
|
check_thunks(dest+4, func+4);
|
|
}
|
|
else
|
|
*(short*)dest = ((func + *(short*)func) - dest);
|
|
|
|
} else {
|
|
if (operandSize == 4)
|
|
*(unsigned long*)dest = *(unsigned long*)func;
|
|
else
|
|
*(unsigned short*)dest = *(unsigned short*)func;
|
|
}
|
|
dest += operandSize;
|
|
}
|
|
func += operandSize;
|
|
bytecount += operandSize;
|
|
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if(opcode == 0xBA || // BT
|
|
opcode == 0x0F || // 3DNow!
|
|
(opcode & 0xFC) == 0x70 || // PSLLW
|
|
(opcode & 0xF7) == 0xA4 || // SHLD
|
|
opcode == 0xC2 ||
|
|
opcode == 0xC4 ||
|
|
opcode == 0xC5 ||
|
|
opcode == 0xC6)
|
|
{
|
|
if (dest)
|
|
*dest++ = *func++;
|
|
else
|
|
func++;
|
|
}
|
|
else if((opcode & 0xF0) == 0x80) // Jcc -i
|
|
{
|
|
if (dest) {
|
|
if (operandSize == 4)
|
|
*(unsigned long*)dest = *(unsigned long*)func;
|
|
else
|
|
*(unsigned short*)dest = *(unsigned short*)func;
|
|
|
|
dest += operandSize;
|
|
}
|
|
func += operandSize;
|
|
bytecount += operandSize;
|
|
}
|
|
}
|
|
}
|
|
|
|
return bytecount;
|
|
}
|
|
|
|
//insert a specific JMP instruction at the given location
|
|
void inject_jmp(void* src, void* dest) {
|
|
*(unsigned char*)src = OP_JMP;
|
|
*(long*)((unsigned char*)src+1) = (long)((unsigned char*)dest - ((unsigned char*)src + OP_JMP_SIZE));
|
|
}
|
|
|
|
//fill a given block with NOPs
|
|
void fill_nop(void* src, unsigned int len) {
|
|
unsigned char* src2 = (unsigned char*)src;
|
|
while (len) {
|
|
*src2++ = OP_NOP;
|
|
--len;
|
|
}
|
|
}
|
|
|
|
void* eval_jump(void* src) {
|
|
unsigned char* addr = (unsigned char*)src;
|
|
|
|
if (!addr) return 0;
|
|
|
|
//import table jump
|
|
if (addr[0] == OP_PREFIX && addr[1] == OP_JMP_SEG) {
|
|
addr += 2;
|
|
addr = *(unsigned char**)addr;
|
|
//TODO: if addr points into the IAT
|
|
return *(void**)addr;
|
|
}
|
|
|
|
//8bit offset
|
|
else if (addr[0] == OP_JMP_BYTE) {
|
|
addr = &addr[OP_JMP_BYTE_SIZE] + *(char*)&addr[1];
|
|
//mangled 32bit jump?
|
|
if (addr[0] == OP_JMP) {
|
|
addr = addr + *(int*)&addr[1];
|
|
}
|
|
return addr;
|
|
}
|
|
/*
|
|
//32bit offset
|
|
else if (addr[0] == OP_JMP) {
|
|
addr = &addr[OP_JMP_SIZE] + *(int*)&addr[1];
|
|
}
|
|
*/
|
|
|
|
return addr;
|
|
}
|
|
/*
|
|
from ms detours package
|
|
static bool detour_is_imported(PBYTE pbCode, PBYTE pbAddress)
|
|
{
|
|
MEMORY_BASIC_INFORMATION mbi;
|
|
VirtualQuery((PVOID)pbCode, &mbi, sizeof(mbi));
|
|
__try {
|
|
PIMAGE_DOS_HEADER pDosHeader = (PIMAGE_DOS_HEADER)mbi.AllocationBase;
|
|
if (pDosHeader->e_magic != IMAGE_DOS_SIGNATURE) {
|
|
return false;
|
|
}
|
|
|
|
PIMAGE_NT_HEADERS pNtHeader = (PIMAGE_NT_HEADERS)((PBYTE)pDosHeader +
|
|
pDosHeader->e_lfanew);
|
|
if (pNtHeader->Signature != IMAGE_NT_SIGNATURE) {
|
|
return false;
|
|
}
|
|
|
|
if (pbAddress >= ((PBYTE)pDosHeader +
|
|
pNtHeader->OptionalHeader
|
|
.DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].VirtualAddress) &&
|
|
pbAddress < ((PBYTE)pDosHeader +
|
|
pNtHeader->OptionalHeader
|
|
.DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].VirtualAddress +
|
|
pNtHeader->OptionalHeader
|
|
.DataDirectory[IMAGE_DIRECTORY_ENTRY_IAT].Size)) {
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
__except(EXCEPTION_EXECUTE_HANDLER) {
|
|
return false;
|
|
}
|
|
}
|
|
*/
|