NtOpenKeyEx - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
#ifndef _NTREGAPI_H

/**
 * Opens an existing registry key with extended options.
 *
 * \param[out] KeyHandle A pointer to a handle that receives the key handle.
 * \param[in] DesiredAccess The access mask that specifies the desired access rights.
 * \param[in] ObjectAttributes A pointer to an OBJECT_ATTRIBUTES structure that specifies the object attributes.
 * \param[in] OpenOptions The options to use when opening the key.
 * \return NTSTATUS Successful or errant status.
 */
NTSYSCALLAPI
NTSTATUS
NTAPI
NtOpenKeyEx(
    _Out_ PHANDLE KeyHandle,
    _In_ ACCESS_MASK DesiredAccess,
    _In_ POBJECT_ATTRIBUTES ObjectAttributes,
    _In_ ULONG OpenOptions
    );

#endif

View code on GitHub
#ifndef _NTZWAPI_H

NTSYSCALLAPI
NTSTATUS
NTAPI
ZwOpenKeyEx(
    _Out_ PHANDLE KeyHandle,
    _In_ ACCESS_MASK DesiredAccess,
    _In_ POBJECT_ATTRIBUTES ObjectAttributes,
    _In_ ULONG OpenOptions
    );

#endif

View code on GitHub
// wdm.h

NTSYSAPI NTSTATUS ZwOpenKeyEx(
  [out] PHANDLE            KeyHandle,
  [in]  ACCESS_MASK        DesiredAccess,
  [in]  POBJECT_ATTRIBUTES ObjectAttributes,
  [in]  ULONG              OpenOptions
);
View the official Windows Driver Kit DDI reference

NtDoc

This function is documented in Windows Driver Kit.

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Windows Driver Kit DDI reference (nf-wdm-zwopenkeyex)

ZwOpenKeyEx function

Description

The ZwOpenKeyEx routine opens an existing registry key.

Parameters

KeyHandle [out]

A pointer to a HANDLE variable into which the routine writes the handle to the key.

DesiredAccess [in]

Specifies the type of access to the key that the caller requests. This parameter is an ACCESS_MASK value. For more information, see the description of the DesiredAccess parameter of the ZwCreateKey routine.

ObjectAttributes [in]

A pointer to the object attributes of the key being opened. This parameter points to an OBJECT_ATTRIBUTES structure that must have been previously initialized by the InitializeObjectAttributes routine. The caller must specify the name of the registry key as the ObjectName parameter in the call to InitializeObjectAttributes. If the caller is not running in a system thread context, it must set the OBJ_KERNEL_HANDLE attribute when it calls InitializeObjectAttributes.

OpenOptions [in]

Specifies the options to apply when opening the key. Set this parameter to zero or to the bitwise OR of one or more of the following REG_OPTION_XXX flag bits:

OpenOptions flag Description
REG_OPTION_OPEN_LINK The key is a symbolic link. This flag is not used by device and intermediate drivers.
REG_OPTION_BACKUP_RESTORE The key should be opened with special privileges that allow backup and restore operations. This flag is not used by device and intermediate drivers.

Return value

ZwOpenKeyEx returns STATUS_SUCCESS if the call succeeds in opening the key. Possible error return values include the following:

Return code Description
STATUS_INVALID_PARAMETER_4 The OpenOptions parameter specifies invalid options.
STATUS_OBJECT_PATH_SYNTAX_BAD The registry path in the object attributes is invalid.
STATUS_OBJECT_NAME_NOT_FOUND The registry key name in the object attributes was not found.
STATUS_OBJECT_TYPE_MISMATCH The named registry key is a symbolic link, but the REG_OPTION_OPEN_LINK flag bit is not set in OpenOptions.
STATUS_ACCESS_DENIED The caller did not have the required access rights to open a handle for the named registry key.
STATUS_INSUFFICIENT_RESOURCES A memory allocation operation failed.

Remarks

This routine supplies a handle with which the caller can access a registry key. If the specified key does not exist, the routine returns an error status value and does not supply a key handle.

The ZwOpenKey routine is similar to ZwOpenKeyEx but does not accept an OpenOptions parameter. The OpenOptions parameter of ZwOpenKeyEx enables the caller to open a key that is a symbolic link, or to open a key for backup and restore operations. A call to ZwOpenKeyEx with OpenOptions = 0 is equivalent to a call to ZwOpenKey.

After the handle pointed to by KeyHandle is no longer in use, the driver must call ZwClose to close it.

ZwOpenKeyEx ignores the security information in the structure that the ObjectAttributes parameter points to.

If the kernel-mode caller is not running in a system thread context, it must ensure that any handles it creates are kernel handles. Otherwise, the handle can be accessed by the process in whose context the driver is running. For more information, see Object Handles.

For more information about working with registry keys in kernel mode, see Using the Registry in a Driver.

See also

ACCESS_MASK

InitializeObjectAttributes

OBJECT_ATTRIBUTES

ZwClose

ZwOpenKey

View the official Windows Driver Kit DDI reference

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