132 lines
4.8 KiB
Plaintext
132 lines
4.8 KiB
Plaintext
This file describes the internals of ul\drv\nt4hack.h that enable building
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UL for NT5 and NT4.
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1. The symbol TARGET_NT4 is defined when building for NT4; it is not
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defined when building for NT5.
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2. A portion of the NT4 build environment must be used to build NT4-
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compatible drivers. This is necessary because:
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a. _except_handler3 is part of the kernel-mode exception
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handling/dispatching mechanism.
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b. All kernel-mode drivers link to ntoskrnl.lib. This is a
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hybrid link-library containing mostly import definitions
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for those routines exported by ntoskrnl.exe. This library
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also contains the actual implementations of a few routines.
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c. The NT4 version of ntoskrnl.lib contains the actual
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_except_handler3 implemenation. As a result, each NT4 driver
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contains a copy of this _except_handler3 implementation.
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d. The NT5 version of ntoskrnl.lib contains an import
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definition for _except_handler3. As a result, each NT5
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driver imports _except_handler3 from the kernel.
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e. Since NT5 drivers import _except_handler3 from the kernel,
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and _except_handler3 is not exported from the NT4 kernel,
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then NT5 drivers will not load under NT4.
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3. When the build target is NT4, nt4hack.h manually #includes basetsd.h.
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This file is #included by ntdef.h in the NT5 build environment, but
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does not exist in the NT4 build environment. #including this file
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enables UL to use the pointer-size-neutral types (such as SIZE_T
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and ULONG_PTR), even on NT4 builds.
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4. nt4hack.h defines a few macros & constants newly introduced in the
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NT5 build environment. These include C_ASSERT, EXTERN_C, and
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ANSI_NULL.
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5. The function prototypes for ExInterlockedCompareExchange64() and
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InterlockedCompareExchange() differ between the NT4 and NT5 build
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environments. For NT4 they are defined as:
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NTKERNELAPI
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ULONGLONG
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FASTCALL
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ExInterlockedCompareExchange64(
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IN PULONGLONG Destination,
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IN PULONGLONG Exchange,
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IN PULONGLONG Comperand,
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IN PKSPIN_LOCK Lock
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);
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PVOID
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FASTCALL
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InterlockedCompareExchange(
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IN OUT PVOID *Destination,
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IN PVOID ExChange,
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IN PVOID Comperand
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);
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Under NT5 they are defined as:
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NTKERNELAPI
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LONGLONG
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FASTCALL
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ExInterlockedCompareExchange64(
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IN PLONGLONG Destination,
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IN PLONGLONG Exchange,
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IN PLONGLONG Comperand,
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IN PKSPIN_LOCK Lock
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);
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NTKERNELAPI
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LONG
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FASTCALL
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InterlockedCompareExchange(
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IN OUT PLONG Destination,
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IN LONG ExChange,
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IN LONG Comperand
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);
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nt4hack.h #defines UlInterlockedCompareExchange64() and
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UlInterlockedCompareExchange() with a few key type casts to ensure
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commonality between platforms.
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6. NT5 introduced the OBJ_KERNEL_HANDLE flag. This flag may be set in
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the Attributes field of the OBJECT_ATTRIBUTES structure used as a
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parameter for many NT APIs that create named objects. When an
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object is opened or created with this flag set, the object is created
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or opened using the security context of the calling thread, but the
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resulting handle is only valid in the system process. Since the handle
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is only valid in the system process, it is impossible for a user-mode
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process to close, duplicate, or otherwise manipulate the handle or
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the underlying object.
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This is a Good Thing. Unfortunately, NT4 does not support this flag.
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Fortunately, NT4 supports the KeAttachProcess() and KeDetachProcess()
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APIs. KeAttachProcess() allows a thread in one process to attach to
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the address space & handle table of another process. Any handles
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created while attached to another process are only valid in the
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context of the attached process.
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nt4hack.h hides these differences by defining:
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UL_KERNEL_HANDLE
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UlAttachToSystemProcess()
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UlDetachFromSystemProcess()
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UlCloseSystemHandle()
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Under NT4, UL_KERNEL_HANDLE is 0; under NT5 it is OBJ_KERNEL_HANDLE.
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UL sets this flag whenever initializing an OBJECT_ATTRIBUTES structure.
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Under NT4, UlAttachToSystemProcess() calls KeAttachProcess() to attach
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to the system process; under NT5 it is a no-op.
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Under NT4, UlDetachFromSystemProcess() calls KeDetachProcess(); under
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NT5 it is a no-op.
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UlCloseSystemHandle() calls UlAttachToSystemProcess(), ZwClose() to
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close the specified handle, then UlDetachFromSystemProcess(). So,
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under NT5, UlCloseSystemHandle() is basically a #define to ZwClose().
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Under NT4, it must attach before the close and detach afterwards.
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