Windows 驱动开发库里面提供了函数 LdrRegisterDllNotification , LdrUnregisterDllNotification ， 可以让你监视进程装载/卸载DLL 的事件。 当你想在某个DLL被加载的时候Hook它的函数； 或者当你想在某个DLL推出之前做一些保存清理工作； 或者当你想阻止某个DLL 被加载（比如外挂） .... 这个机制正可以派上用场 。

以下是代码示例如何使用 LdrRegisterDllNotification , LdrUnregisterDllNotification 监听DLL装载/卸载。

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#include <Ntsecapi.h> // DDK   
typedef const UNICODE_STRING* PCUNICODE_STRING;   
  
typedef struct _LDR_DLL_LOADED_NOTIFICATION_DATA {   
    ULONG Flags;                    //Reserved.   
    PCUNICODE_STRING FullDllName;   //The full path name of the DLL module.   
    PCUNICODE_STRING BaseDllName;   //The base file name of the DLL module.   
    PVOID DllBase;                  //A pointer to the base address for the DLL in memory.   
    ULONG SizeOfImage;              //The size of the DLL image, in bytes.   
} LDR_DLL_LOADED_NOTIFICATION_DATA, *PLDR_DLL_LOADED_NOTIFICATION_DATA;   
  
typedef struct _LDR_DLL_UNLOADED_NOTIFICATION_DATA {   
    ULONG Flags;                    //Reserved.   
    PCUNICODE_STRING FullDllName;   //The full path name of the DLL module.   
    PCUNICODE_STRING BaseDllName;   //The base file name of the DLL module.   
    PVOID DllBase;                  //A pointer to the base address for the DLL in memory.   
    ULONG SizeOfImage;              //The size of the DLL image, in bytes.   
} LDR_DLL_UNLOADED_NOTIFICATION_DATA, *PLDR_DLL_UNLOADED_NOTIFICATION_DATA;   
  
typedef union _LDR_DLL_NOTIFICATION_DATA {   
    LDR_DLL_LOADED_NOTIFICATION_DATA Loaded;   
    LDR_DLL_UNLOADED_NOTIFICATION_DATA Unloaded;   
} LDR_DLL_NOTIFICATION_DATA, *PLDR_DLL_NOTIFICATION_DATA;   
  
typedef const PLDR_DLL_NOTIFICATION_DATA PCLDR_DLL_NOTIFICATION_DATA;   
  
typedef VOID (NTAPI *PLDR_DLL_NOTIFICATION_FUNCTION)(ULONG NotificationReason, PCLDR_DLL_NOTIFICATION_DATA NotificationData, PVOID Context);   
typedef NTSTATUS (NTAPI *pfnLdrRegisterDllNotification)(ULONG Flags, PLDR_DLL_NOTIFICATION_FUNCTION NotificationFunction, void* Context, void **Cookie);   
typedef NTSTATUS (NTAPI *pfnLdrUnregisterDllNotification)(void *Cookie);   
  
#define LDR_DLL_NOTIFICATION_REASON_LOADED 1    
#define LDR_DLL_NOTIFICATION_REASON_UNLOADED 2   
  
VOID NTAPI MyLdrDllNotification(   
  ULONG NotificationReason,   
  PCLDR_DLL_NOTIFICATION_DATA NotificationData,   
  PVOID Context   
)   
{   
    switch (NotificationReason)   
    {   
    case LDR_DLL_NOTIFICATION_REASON_LOADED:   
        printf ("Dll Loaded: %S\n", NotificationData->Loaded.FullDllName->Buffer);   
        break;   
    case LDR_DLL_NOTIFICATION_REASON_UNLOADED:   
        printf ("Dll Unloaded: %S\n", NotificationData->Unloaded.FullDllName->Buffer);   
        break;   
    }   
}   
  
int _tmain(int argc, _TCHAR* argv[])   
{   
  
    HMODULE hModule = GetModuleHandleW(L"NTDLL.DLL");   
            
         // 取得函数指针   
    pfnLdrRegisterDllNotification pLdrRegisterDllNotification = (pfnLdrRegisterDllNotification)GetProcAddress(hModule, "LdrRegisterDllNotification");   
    pfnLdrUnregisterDllNotification pLdrUnregisterDllNotification = (pfnLdrUnregisterDllNotification)GetProcAddress(hModule, "LdrUnregisterDllNotification");   
    void *pvCookie = NULL;   
  
         // 初始化   
    pLdrRegisterDllNotification(0, MyLdrDllNotification, NULL, &pvCookie);   
       
    // 测试DLL 装载   
    HMODULE hLoad = ::LoadLibraryW(L"mshtml.dll");   
    Sleep(1000);   
         // 测试 DLL 卸载   
    ::FreeLibrary(hLoad);   
  
         // 清除   
    if (pvCookie)   
    {   
        pLdrUnregisterDllNotification(pvCookie);   
        pvCookie = NULL;   
    }   
  
    return 0;   
}  
#include <Ntsecapi.h> // DDK
typedef const UNICODE_STRING* PCUNICODE_STRING;

typedef struct _LDR_DLL_LOADED_NOTIFICATION_DATA {
    ULONG Flags;                    //Reserved.
    PCUNICODE_STRING FullDllName;   //The full path name of the DLL module.
    PCUNICODE_STRING BaseDllName;   //The base file name of the DLL module.
    PVOID DllBase;                  //A pointer to the base address for the DLL in memory.
    ULONG SizeOfImage;              //The size of the DLL image, in bytes.
} LDR_DLL_LOADED_NOTIFICATION_DATA, *PLDR_DLL_LOADED_NOTIFICATION_DATA;

typedef struct _LDR_DLL_UNLOADED_NOTIFICATION_DATA {
    ULONG Flags;                    //Reserved.
    PCUNICODE_STRING FullDllName;   //The full path name of the DLL module.
    PCUNICODE_STRING BaseDllName;   //The base file name of the DLL module.
    PVOID DllBase;                  //A pointer to the base address for the DLL in memory.
    ULONG SizeOfImage;              //The size of the DLL image, in bytes.
} LDR_DLL_UNLOADED_NOTIFICATION_DATA, *PLDR_DLL_UNLOADED_NOTIFICATION_DATA;

typedef union _LDR_DLL_NOTIFICATION_DATA {
    LDR_DLL_LOADED_NOTIFICATION_DATA Loaded;
    LDR_DLL_UNLOADED_NOTIFICATION_DATA Unloaded;
} LDR_DLL_NOTIFICATION_DATA, *PLDR_DLL_NOTIFICATION_DATA;

typedef const PLDR_DLL_NOTIFICATION_DATA PCLDR_DLL_NOTIFICATION_DATA;

typedef VOID (NTAPI *PLDR_DLL_NOTIFICATION_FUNCTION)(ULONG NotificationReason, PCLDR_DLL_NOTIFICATION_DATA NotificationData, PVOID Context);
typedef NTSTATUS (NTAPI *pfnLdrRegisterDllNotification)(ULONG Flags, PLDR_DLL_NOTIFICATION_FUNCTION NotificationFunction, void* Context, void **Cookie);
typedef NTSTATUS (NTAPI *pfnLdrUnregisterDllNotification)(void *Cookie);

#define LDR_DLL_NOTIFICATION_REASON_LOADED 1 
#define LDR_DLL_NOTIFICATION_REASON_UNLOADED 2

VOID NTAPI MyLdrDllNotification(
  ULONG NotificationReason,
  PCLDR_DLL_NOTIFICATION_DATA NotificationData,
  PVOID Context
)
{
 switch (NotificationReason)
 {
 case LDR_DLL_NOTIFICATION_REASON_LOADED:
  printf ("Dll Loaded: %S\n", NotificationData->Loaded.FullDllName->Buffer);
  break;
 case LDR_DLL_NOTIFICATION_REASON_UNLOADED:
  printf ("Dll Unloaded: %S\n", NotificationData->Unloaded.FullDllName->Buffer);
  break;
 }
}

int _tmain(int argc, _TCHAR* argv[])
{

 HMODULE hModule = GetModuleHandleW(L"NTDLL.DLL");
         
         // 取得函数指针
 pfnLdrRegisterDllNotification pLdrRegisterDllNotification = (pfnLdrRegisterDllNotification)GetProcAddress(hModule, "LdrRegisterDllNotification");
 pfnLdrUnregisterDllNotification pLdrUnregisterDllNotification = (pfnLdrUnregisterDllNotification)GetProcAddress(hModule, "LdrUnregisterDllNotification");
 void *pvCookie = NULL;

         // 初始化
 pLdrRegisterDllNotification(0, MyLdrDllNotification, NULL, &pvCookie);
 
 // 测试DLL 装载
 HMODULE hLoad = ::LoadLibraryW(L"mshtml.dll");
 Sleep(1000);
         // 测试 DLL 卸载
 ::FreeLibrary(hLoad);

         // 清除
 if (pvCookie)
 {
  pLdrUnregisterDllNotification(pvCookie);
  pvCookie = NULL;
 }

 return 0;
}
 

运行程序， 输出如下。可以证实以上代码监听了 mshtml.dll 的装载和卸载。 而且系统自动装载的其他DLL也被监视到。

Dll Loaded: C:\Windows\system32\mshtml.dll
Dll Loaded: C:\Windows\system32\msls31.dll
Dll Loaded: C:\Windows\system32\VERSION.dll
Dll Unloaded: C:\Windows\system32\mshtml.dll
Dll Unloaded: C:\Windows\system32\VERSION.dll
Dll Unloaded: C:\Windows\system32\msls31.dll