WDF is object based, the objects have to be created and manipulated by function calls to WDF itself.

WDF objects are used by handles! Not their ptr to kernel structure. But for sure they’re backed by a kernel structure (Obviously).

Each WDF object has a lifecycle requirement. See https://learn.microsoft.com/en-us/windows-hardware/drivers/wdf/framework-object-life-cycle.

Notable characteristics of a framework objects is:

• Reference counter
  • Bruh a reference counter.
• Context space
  • Essentially custom data.
• Deletion callback functions
  • For framework objects, there may be attached to some external resource (e.g. memory allocation in context space that needs to be freed by the driver developer). Since WDF manages object lifecycle, it has to have a mechanism to request driver to release resources for object pending deletion.
• Parent object
  • WDF object is organized as a tree of object, with parent-child relationship. When parent is deleted, the framework automatically deletes children.

Objects

ReactOS has implementation of WDF, which is great since they build doxygen!

https://doxygen.reactos.org/d6/d44/classFxObject.html

As visible from above, all WDF object inherits from a base class called FxObject from Wdf0100.

FxObject has a m_Type field, using this field you can quickly find out what type to cast the WDF object to investigate.

https://doxygen.reactos.org/d4/d92/fxtypes_8h_source.html#l00029

enum FX_OBJECT_TYPES_BASE {
 
    FX_TYPES_BASE             = 0x1000,
    FX_TYPES_PACKAGES_BASE    = 0x1100,
    FX_TYPES_IO_TARGET_BASE   = 0x1200,
    FX_ABSTRACT_TYPES_BASE    = 0x1300,
    FX_TYPES_DMA_BASE         = 0x1400,
    FX_TYPES_INTERFACES_BASE  = 0x1500,
};
 
enum FX_OBJECT_TYPES {
    // Use Hex numbers since this the kd default dump value
 
    FX_TYPE_OBJECT               = FX_TYPES_BASE+0x0,
    FX_TYPE_DRIVER               = FX_TYPES_BASE+0x1,
    FX_TYPE_DEVICE               = FX_TYPES_BASE+0x2,
    FX_TYPE_QUEUE                = FX_TYPES_BASE+0x3,
    FX_TYPE_WMI_PROVIDER         = FX_TYPES_BASE+0x4,
    // can be reused             = FX_TYPES_BASE+0x5,
    FX_TYPE_REG_KEY              = FX_TYPES_BASE+0x6,
    FX_TYPE_STRING               = FX_TYPES_BASE+0x7,
    FX_TYPE_REQUEST              = FX_TYPES_BASE+0x8,
    FX_TYPE_LOOKASIDE            = FX_TYPES_BASE+0x9,
    IFX_TYPE_MEMORY              = FX_TYPES_BASE+0xA,
    FX_TYPE_IRPQUEUE             = FX_TYPES_BASE+0xB,
    FX_TYPE_USEROBJECT           = FX_TYPES_BASE+0xC,
    // can be reused               FX_TYPES_BASE+0xD,
    FX_TYPE_COLLECTION           = FX_TYPES_BASE+0xE,
 
    // can be reused             = FX_TYPES_BASE+0x11,
    FX_TYPE_VERIFIERLOCK         = FX_TYPES_BASE+0x12,
    FX_TYPE_SYSTEMTHREAD         = FX_TYPES_BASE+0x13,
    FX_TYPE_MP_DEVICE            = FX_TYPES_BASE+0x14,
    FX_TYPE_DPC                  = FX_TYPES_BASE+0x15,
    FX_TYPE_RESOURCE_IO          = FX_TYPES_BASE+0x16,
    FX_TYPE_RESOURCE_CM          = FX_TYPES_BASE+0x17,
    FX_TYPE_FILEOBJECT           = FX_TYPES_BASE+0x18,
    // can be reused             = FX_TYPES_BASE+0x19,
    // can be reused             = FX_TYPES_BASE+0x20,
    FX_TYPE_RELATED_DEVICE       = FX_TYPES_BASE+0x21,
    FX_TYPE_MEMORY_PREALLOCATED  = FX_TYPES_BASE+0x22,
    FX_TYPE_WAIT_LOCK            = FX_TYPES_BASE+0x23,
    FX_TYPE_SPIN_LOCK            = FX_TYPES_BASE+0x24,
    FX_TYPE_WORKITEM             = FX_TYPES_BASE+0x25,
    FX_TYPE_CLEANUPLIST          = FX_TYPES_BASE+0x26,
    FX_TYPE_INTERRUPT            = FX_TYPES_BASE+0x27,
    FX_TYPE_TIMER                = FX_TYPES_BASE+0x28,
    FX_TYPE_CHILD_LIST           = FX_TYPES_BASE+0x29,
    FX_TYPE_DEVICE_BASE          = FX_TYPES_BASE+0x30,
    FX_TYPE_SYSTEMWORKITEM       = FX_TYPES_BASE+0x31,
    FX_TYPE_REQUEST_MEMORY       = FX_TYPES_BASE+0x32,
    FX_TYPE_DISPOSELIST          = FX_TYPES_BASE+0x33,
    FX_TYPE_WMI_INSTANCE         = FX_TYPES_BASE+0x34,
    FX_TYPE_IO_RES_LIST          = FX_TYPES_BASE+0x35,
    FX_TYPE_CM_RES_LIST          = FX_TYPES_BASE+0x36,
    FX_TYPE_IO_RES_REQ_LIST      = FX_TYPES_BASE+0x37,
 
    FX_TYPE_PACKAGE_IO           = FX_TYPES_PACKAGES_BASE+0x0,
    FX_TYPE_PACKAGE_FDO          = FX_TYPES_PACKAGES_BASE+0x1,
    FX_TYPE_PACKAGE_PDO          = FX_TYPES_PACKAGES_BASE+0x2,
    FX_TYPE_WMI_IRP_HANDLER      = FX_TYPES_PACKAGES_BASE+0x3,
    FX_TYPE_PACKAGE_GENERAL      = FX_TYPES_PACKAGES_BASE+0x4,
    FX_TYPE_DEFAULT_IRP_HANDLER  = FX_TYPES_PACKAGES_BASE+0x5,
    FX_TYPE_WMI_TRACING_IRP_HANDLER = FX_TYPES_PACKAGES_BASE+0x6,
 
    FX_TYPE_IO_TARGET            = FX_TYPES_IO_TARGET_BASE+0x0,
    FX_TYPE_IO_TARGET_REMOTE     = FX_TYPES_IO_TARGET_BASE+0x1,
    FX_TYPE_IO_TARGET_USB_DEVICE = FX_TYPES_IO_TARGET_BASE+0x2,
    FX_TYPE_IO_TARGET_USB_PIPE   = FX_TYPES_IO_TARGET_BASE+0x3,
    FX_TYPE_USB_INTERFACE        = FX_TYPES_IO_TARGET_BASE+0x4,
    FX_TYPE_IO_TARGET_SELF       = FX_TYPES_IO_TARGET_BASE+0x5,
 
    FX_TYPE_DMA_ENABLER          = FX_TYPES_DMA_BASE+0x0,
    FX_TYPE_DMA_TRANSACTION      = FX_TYPES_DMA_BASE+0x1,
    FX_TYPE_COMMON_BUFFER        = FX_TYPES_DMA_BASE+0x2,
 
    // Interfaces
    FX_TYPE_IASSOCIATE           = FX_TYPES_INTERFACES_BASE+0x01,
    // unused
    FX_TYPE_IHASCALLBACKS        = FX_TYPES_INTERFACES_BASE+0x03,
    // unused                    = FX_TYPES_INTERFACES_BASE+0x04,
 
    FX_TYPE_NONE                 = 0xFFFF,
};