AuxKlibQueryModuleInformation function (aux_klib.h)

Article
10/21/2021

The AuxKlibQueryModuleInformation routine retrieves information about the image modules that the operating system has loaded.

Syntax

NTSTATUS AuxKlibQueryModuleInformation(
  [in, out]       PULONG BufferSize,
  [in]            ULONG  ElementSize,
  [out, optional] PVOID  QueryInfo
);

Parameters

[in, out] BufferSize

A pointer to a location that contains or receives a buffer size, in bytes. If QueryInfo is NULL, the location receives the number of bytes that the driver must allocate for the array that receives the retrieved information. If QueryInfo is not NULL, the location must contain the specified number of bytes.

[in] ElementSize

The size, in bytes, of each element of the array that QueryInfo points to. This value must be sizeof(AUX_MODULE_BASIC_INFO) or sizeof(AUX_MODULE_EXTENDED_INFO).

[out, optional] QueryInfo

A pointer to an array of AUX_MODULE_BASIC_INFO or AUX_MODULE_EXTENDED_INFO structures that receives information about loaded image modules. If this pointer is NULL, AuxKlibQueryModuleInformation writes the required buffer size to the location that BufferSize points to.

Return value

AuxKlibQueryModuleInformation returns STATUS_SUCCESS if the operation succeeds. AuxKlibQueryModuleInformation returns STATUS_BUFFER_TOO_SMALL if the QueryInfo pointer is not NULL and the driver-supplied BufferSize value is too small.

The routine might return other NTSTATUS values.

Remarks

To obtain information about the operating system's loaded image modules, a driver must:

Call AuxKlibQueryModuleInformation with a NULL QueryInfo pointer. After AuxKlibQueryModuleInformation returns, the location that the BufferSize parameter points to will contain the number of bytes that the driver will have to allocate for the array.
Call a memory allocation routine, such as ExAllocatePoolWithTag, to allocate a buffer for the array.
Call AuxKlibQueryModuleInformation again. This time, the QueryInfo pointer must contain the address of the allocated buffer. After AuxKlibQueryModuleInformation returns, the buffer contains an array of module information.

The number of loaded modules can change between the first and second calls to AuxKlibQueryModuleInformation. As a result, the second call to AuxKlibQueryModuleInformation might return STATUS_BUFFER_TOO_SMALL even if the driver allocates a buffer that is based on the size that was obtained from the first call.

If a call to AuxKlibQueryModuleInformation succeeds, the routine writes an ImageBase value to each element in the QueryInfo array. Each ImageBase value is a pointer to the base of a loaded driver image. This pointer remains valid only while the driver remains loaded. The caller should assume that the driver can be unloaded at any time unless the caller can guarantee otherwise. For example, a driver might be unloaded between a call to AuxKlibQueryModuleInformation that obtains a pointer to the driver image and a call to AuxKlibGetImageExportDirectory that uses this pointer.

Drivers must call AuxKlibInitialize before calling AuxKlibQueryModuleInformation.

Examples

The following code example illustrates the steps that are listed in the preceding Remarks section.

NTSTATUS  status;
ULONG  modulesSize;
AUX_MODULE_EXTENDED_INFO*  modules;
ULONG  numberOfModules;
//
// Get the required array size.
//
status = AuxKlibQueryModuleInformation(
                                       &modulesSize,
                                       sizeof(AUX_MODULE_EXTENDED_INFO),
                                       NULL
                                       );

if (!NT_SUCCESS(status) || modulesSize == 0) {
    break;
    }

//
// Calculate the number of modules.
//
numberOfModules = modulesSize / sizeof(AUX_MODULE_EXTENDED_INFO);

//
// Allocate memory to receive data.
//
modules = 
    (AUX_MODULE_EXTENDED_INFO*) ExAllocatePoolWithTag(
                                      PagedPool,
                                      modulesSize,
                                      '3LxF'
                                      );
if (modules == NULL) {
    status = STATUS_INSUFFICIENT_RESOURCES;
    break;
    }

RtlZeroMemory(
              modules,
              modulesSize
              );

//
// Obtain the module information.
//
status = AuxKlibQueryModuleInformation(
                                       &modulesSize,
                                       sizeof(AUX_MODULE_EXTENDED_INFO),
                                       modules
                                       );
if (!NT_SUCCESS(status)) {
    break;
    }

Requirements

Requirement	Value
Minimum supported client	Supported starting with Windows 2000.
Target Platform	Universal
Header	aux_klib.h (include Aux_klib.h)
Library	Aux_Klib.lib
IRQL	PASSIVE_LEVEL

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