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| /******************************************************************************
Module: APIHook.cpp
Notices: Copyright (c) 2000 Jeffrey Richter
******************************************************************************/
#include <Windows.h>
#include <ImageHlp.h>
#include <assert.h>
//Avec MinGW ajouter la lib ImageHlp au link
#pragma comment(lib, "ImageHlp")
#include "CAPIHook.h"
#include "CToolhelp.h"
///////////////////////////////////////////////////////////////////////////////
// When an application runs on Windows 98 under a debugger, the debugger
// makes the module's import section point to a stub that calls the desired
// function. To account for this, the code in this module must do some crazy
// stuff. These variables are needed to help with the crazy stuff.
// The highest private memory address (used for Windows 98 only)
PVOID CAPIHook::sm_pvMaxAppAddr = NULL;
const BYTE cPushOpCode = 0x68; // The PUSH opcode on x86 platforms
///////////////////////////////////////////////////////////////////////////////
// The head of the linked-list of CAPIHook objects
CAPIHook* CAPIHook::sm_pHead = NULL;
///////////////////////////////////////////////////////////////////////////////
CAPIHook::CAPIHook(PSTR pszCalleeModName, PSTR pszFuncName, PROC pfnHook,
BOOL fExcludeAPIHookMod) {
if (sm_pvMaxAppAddr == NULL) {
// Functions with address above lpMaximumApplicationAddress require
// special processing (Windows 98 only)
SYSTEM_INFO si;
GetSystemInfo(&si);
sm_pvMaxAppAddr = si.lpMaximumApplicationAddress;
}
m_pNext = sm_pHead; // The next node was at the head
sm_pHead = this; // This node is now at the head
// Save information about this hooked function
m_pszCalleeModName = pszCalleeModName;
m_pszFuncName = pszFuncName;
m_pfnHook = pfnHook;
m_fExcludeAPIHookMod = fExcludeAPIHookMod;
HMODULE hMod = GetModuleHandleA(pszCalleeModName);
assert(hMod != NULL); //Le module n'existe pas
m_pfnOrig = GetProcAddressRaw(hMod, m_pszFuncName);
assert(m_pfnOrig != NULL); //La focntion n'existe pas
if (m_pfnOrig > sm_pvMaxAppAddr) {
// The address is in a shared DLL; the address needs fixing up
PBYTE pb = (PBYTE) m_pfnOrig;
if (pb[0] == cPushOpCode) {
// Skip over the PUSH op code and grab the real address
PVOID pv = * (PVOID*) &pb[1];
m_pfnOrig = (PROC) pv;
}
}
// Hook this function in all currently loaded modules
ReplaceIATEntryInAllMods(m_pszCalleeModName, m_pfnOrig, m_pfnHook,
m_fExcludeAPIHookMod);
}
///////////////////////////////////////////////////////////////////////////////
CAPIHook::~CAPIHook() {
// Unhook this function from all modules
ReplaceIATEntryInAllMods(m_pszCalleeModName, m_pfnHook, m_pfnOrig,
m_fExcludeAPIHookMod);
// Remove this object from the linked list
CAPIHook* p = sm_pHead;
if (p == this) { // Removing the head node
sm_pHead = p->m_pNext;
} else {
BOOL fFound = FALSE;
// Walk list from head and fix pointers
for (; !fFound && (p->m_pNext != NULL); p = p->m_pNext) {
if (p->m_pNext == this) {
// Make the node that points to us point to the our next node
p->m_pNext = p->m_pNext->m_pNext;
fFound = TRUE;
}
}
assert(fFound);
}
}
///////////////////////////////////////////////////////////////////////////////
// NOTE: This function must NOT be inlined
FARPROC CAPIHook::GetProcAddressRaw(HMODULE hmod, PCSTR pszProcName) {
return(::GetProcAddress(hmod, pszProcName));
}
///////////////////////////////////////////////////////////////////////////////
// Returns the HMODULE that contains the specified memory address
static HMODULE ModuleFromAddress(PVOID pv) {
MEMORY_BASIC_INFORMATION mbi;
return((VirtualQuery(pv, &mbi, sizeof(mbi)) != 0)
? (HMODULE) mbi.AllocationBase : NULL);
}
///////////////////////////////////////////////////////////////////////////////
void CAPIHook::ReplaceIATEntryInAllMods(PCSTR pszCalleeModName,
PROC pfnCurrent, PROC pfnNew, BOOL fExcludeAPIHookMod) {
HMODULE hmodThisMod = fExcludeAPIHookMod ? ModuleFromAddress((void*)ReplaceIATEntryInAllMods) : NULL;
// Get the list of modules in this process
CToolhelp th(TH32CS_SNAPMODULE, GetCurrentProcessId());
MODULEENTRY32 me = { sizeof(me) };
for (BOOL fOk = th.ModuleFirst(&me); fOk; fOk = th.ModuleNext(&me)) {
// NOTE: We don't hook functions in our own module
if (me.hModule != hmodThisMod) {
// Hook this function in this module
ReplaceIATEntryInOneMod(
pszCalleeModName, pfnCurrent, pfnNew, me.hModule);
}
}
}
///////////////////////////////////////////////////////////////////////////////
void CAPIHook::ReplaceIATEntryInOneMod(PCSTR pszCalleeModName,
PROC pfnCurrent, PROC pfnNew, HMODULE hmodCaller) {
// Get the address of the module's import section
ULONG ulSize;
PIMAGE_IMPORT_DESCRIPTOR pImportDesc = (PIMAGE_IMPORT_DESCRIPTOR)
ImageDirectoryEntryToData(hmodCaller, TRUE, IMAGE_DIRECTORY_ENTRY_IMPORT, &ulSize);
if (pImportDesc == NULL)
return; // This module has no import section
// Find the import descriptor containing references to callee's functions
for (; pImportDesc->Name; pImportDesc++) {
PSTR pszModName = (PSTR) ((PBYTE) hmodCaller + pImportDesc->Name);
if (lstrcmpiA(pszModName, pszCalleeModName) == 0)
break; // Found
}
if (pImportDesc->Name == 0)
return; // This module doesn't import any functions from this callee
// Get caller's import address table (IAT) for the callee's functions
PIMAGE_THUNK_DATA pThunk = (PIMAGE_THUNK_DATA)
((PBYTE) hmodCaller + pImportDesc->FirstThunk);
// Replace current function address with new function address
for (; pThunk->u1.Function; pThunk++) {
// Get the address of the function address
PROC* ppfn = (PROC*) &pThunk->u1.Function;
// Is this the function we're looking for?
BOOL fFound = (*ppfn == pfnCurrent);
if (!fFound && (*ppfn > sm_pvMaxAppAddr)) {
// If this is not the function and the address is in a shared DLL,
// then maybe we're running under a debugger on Windows 98. In this
// case, this address points to an instruction that may have the
// correct address.
PBYTE pbInFunc = (PBYTE) *ppfn;
if (pbInFunc[0] == cPushOpCode) {
// We see the PUSH instruction, the real function address follows
ppfn = (PROC*) &pbInFunc[1];
// Is this the function we're looking for?
fFound = (*ppfn == pfnCurrent);
}
}
if (fFound) {
// The addresses match, change the import section address
WriteProcessMemory(GetCurrentProcess(), ppfn, &pfnNew,
sizeof(pfnNew), NULL);
return; // We did it, get out
}
}
// If we get to here, the function is not in the caller's import section
}
///////////////////////////////////////////////////////////////////////////////
// Hook LoadLibrary functions and GetProcAddress so that hooked functions
// are handled correctly if these functions are called.
CAPIHook CAPIHook::sm_LoadLibraryA ("Kernel32.dll", "LoadLibraryA", (PROC)CAPIHook::LoadLibraryA, TRUE);
CAPIHook CAPIHook::sm_LoadLibraryW ("Kernel32.dll", "LoadLibraryW", (PROC)CAPIHook::LoadLibraryW, TRUE);
CAPIHook CAPIHook::sm_LoadLibraryExA("Kernel32.dll", "LoadLibraryExA", (PROC)CAPIHook::LoadLibraryExA, TRUE);
CAPIHook CAPIHook::sm_LoadLibraryExW("Kernel32.dll", "LoadLibraryExW", (PROC)CAPIHook::LoadLibraryExW, TRUE);
CAPIHook CAPIHook::sm_GetProcAddress("Kernel32.dll", "GetProcAddress", (PROC)CAPIHook::GetProcAddress, TRUE);
///////////////////////////////////////////////////////////////////////////////
void CAPIHook::FixupNewlyLoadedModule(HMODULE hmod, DWORD dwFlags) {
// If a new module is loaded, hook the hooked functions
if ((hmod != NULL) && ((dwFlags & LOAD_LIBRARY_AS_DATAFILE) == 0)) {
for (CAPIHook* p = sm_pHead; p != NULL; p = p->m_pNext) {
ReplaceIATEntryInOneMod(p->m_pszCalleeModName,
p->m_pfnOrig, p->m_pfnHook, hmod);
}
}
}
///////////////////////////////////////////////////////////////////////////////
HMODULE WINAPI CAPIHook::LoadLibraryA(PCSTR pszModulePath) {
HMODULE hmod = ::LoadLibraryA(pszModulePath);
FixupNewlyLoadedModule(hmod, 0);
return(hmod);
}
///////////////////////////////////////////////////////////////////////////////
HMODULE WINAPI CAPIHook::LoadLibraryW(PCWSTR pszModulePath) {
HMODULE hmod = ::LoadLibraryW(pszModulePath);
FixupNewlyLoadedModule(hmod, 0);
return(hmod);
}
///////////////////////////////////////////////////////////////////////////////
HMODULE WINAPI CAPIHook::LoadLibraryExA(PCSTR pszModulePath,
HANDLE hFile, DWORD dwFlags) {
HMODULE hmod = ::LoadLibraryExA(pszModulePath, hFile, dwFlags);
FixupNewlyLoadedModule(hmod, dwFlags);
return(hmod);
}
///////////////////////////////////////////////////////////////////////////////
HMODULE WINAPI CAPIHook::LoadLibraryExW(PCWSTR pszModulePath,
HANDLE hFile, DWORD dwFlags) {
HMODULE hmod = ::LoadLibraryExW(pszModulePath, hFile, dwFlags);
FixupNewlyLoadedModule(hmod, dwFlags);
return(hmod);
}
///////////////////////////////////////////////////////////////////////////////
FARPROC WINAPI CAPIHook::GetProcAddress(HMODULE hmod, PCSTR pszProcName) {
// Get the true address of the function
FARPROC pfn = GetProcAddressRaw(hmod, pszProcName);
// Is it one of the functions that we want hooked?
CAPIHook* p = sm_pHead;
for (; (pfn != NULL) && (p != NULL); p = p->m_pNext) {
if (pfn == p->m_pfnOrig) {
// The address to return matches an address we want to hook
// Return the hook function address instead
pfn = p->m_pfnHook;
break;
}
}
return(pfn);
} |
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