ZwCreateKey function (wdm.h)

Article
01/13/2023

The ZwCreateKey routine creates a new registry key or opens an existing one.

Syntax

NTSYSAPI NTSTATUS ZwCreateKey(
  [out]           PHANDLE            KeyHandle,
  [in]            ACCESS_MASK        DesiredAccess,
  [in]            POBJECT_ATTRIBUTES ObjectAttributes,
                  ULONG              TitleIndex,
  [in, optional]  PUNICODE_STRING    Class,
  [in]            ULONG              CreateOptions,
  [out, optional] PULONG             Disposition
);

Parameters

[out] KeyHandle

Pointer to a HANDLE variable that receives a handle to the key.

[in] DesiredAccess

Specifies an ACCESS_MASK value that determines the requested access to the object. In addition to the access rights that are defined for all types of objects (see ACCESS_MASK), the caller can specify one or more of the following access rights, which are specific to object directories:

DesiredAccess flag	Allows caller to do this
KEY_QUERY_VALUE	Read key values.
KEY_SET_VALUE	Write key values.
KEY_CREATE_SUB_KEY	Create subkeys for the key.
KEY_ENUMERATE_SUB_KEYS	Read the key's subkeys.
KEY_CREATE_LINK	Create a symbolic link to the key. This flag is not used by device and intermediate drivers.
KEY_NOTIFY	Ask to receive notification when the name, value, or attributes of the key change. For more information, see ZwNotifyChangeKey.

The caller can also specify one of the following constants, which combines several ACCESS_MASK flags.

Constant	Consists of these ACCESS_MASK flags
KEY_READ	STANDARD_RIGHTS_READ, KEY_QUERY_VALUE, KEY_ENUMERATE_SUB_KEYS, and KEY_NOTIFY
KEY_WRITE	STANDARD_RIGHTS_WRITE, KEY_SET_VALUE, and KEY_CREATE_SUB_KEY
KEY_EXECUTE	Same as KEY_READ.
KEY_ALL_ACCESS	STANDARD_RIGHTS_ALL, KEY_QUERY_VALUE, KEY_SET_VALUE, KEY_CREATE_SUB_KEY, KEY_ENUMERATE_SUB_KEYS, KEY_NOTIFY, and KEY_CREATE_LINK

[in] ObjectAttributes

Pointer to an OBJECT_ATTRIBUTES structure that specifies the object name and other attributes. Use InitializeObjectAttributes to initialize this structure. If the caller is not running in a system thread context, it must set the OBJ_KERNEL_HANDLE attribute when it calls InitializeObjectAttributes.

TitleIndex

Device and intermediate drivers set this parameter to zero.

[in, optional] Class

Pointer to a Unicode string that contains the key's object class. This information is used by the configuration manager.

[in] CreateOptions

Specifies the options to apply when creating or opening a key, specified as a compatible combination of the following flags.

CreateOptions flag	Description
REG_OPTION_VOLATILE	Key is not preserved when the system is rebooted.
REG_OPTION_NON_VOLATILE	Key is preserved when the system is rebooted.
REG_OPTION_CREATE_LINK	The newly created key is a symbolic link. This flag is not used by device and intermediate drivers.
REG_OPTION_BACKUP_RESTORE	Key should be created or opened with special privileges that allow backup and restore operations. This flag is not used by device and intermediate drivers.

[out, optional] Disposition

Pointer to a variable that receives a value indicating whether a new key was created or an existing one opened.

Disposition value	Description
REG_CREATED_NEW_KEY	A new key was created.
REG_OPENED_EXISTING_KEY	An existing key was opened.

Return value

ZwCreateKey returns STATUS_SUCCESS on success, or the appropriate NTSTATUS error code on failure.

Remarks

ZwCreateKey supplies a handle that the caller can use to manipulate a registry key. For more information, see Using the Registry in a Driver.

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

There are two alternate ways to specify the name of the file to be created or opened with ZwCreateKey:

As a fully qualified pathname, supplied in the ObjectName member of the input ObjectAttributes. The pathnames of registry keys begin with \Registry.
As pathname relative to another registry key, represented by the handle in the RootDirectory member of the input ObjectAttributes.

If the key specified by ObjectAttributes does not exist, the routine attempts to create the key. For this attempt to succeed, the new key must be a direct subkey of the key that is referred to by RootDirectory, and the key that RootDirectory refers to must have been opened for KEY_CREATE_SUB_KEY access.

If the specified key already exists, it is opened and its value is not affected in any way.

The security attributes specified by ObjectAttributes when a key is created determine whether the specified DesiredAccess is granted on subsequent calls to ZwCreateKey and ZwOpenKey.

If the caller is not running in a system thread context, it must ensure that any handles it creates are private 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, see Using the Registry in a Driver.

If the call to this function occurs in user mode, you should use the name "NtCreateKey" instead of "ZwCreateKey".

The NtCreateKey routine in the Windows kernel is not directly accessible to kernel-mode drivers.

For calls from kernel-mode drivers, the NtXxx and ZwXxx versions of a Windows Native System Services routine can behave differently in the way that they handle and interpret input parameters. For more information about the relationship between the NtXxx and ZwXxx versions of a routine, see Using Nt and Zw Versions of the Native System Services Routines.

Requirements

Requirement	Value
Target Platform	Universal
Header	wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	PASSIVE_LEVEL
DDI compliance rules	HwStorPortProhibitedDDIs(storport), IrqlZwPassive(wdm), PowerIrpDDis(wdm), ZwRegistryCreate(storport), ZwRegistryCreate(storport), ZwRegistryCreate(wdm), ZwRegistryOpen(wdm)