138 lines
2.8 KiB
C
138 lines
2.8 KiB
C
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/*++
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Copyright (c) 1989 Microsoft Corporation
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Module Name:
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luid.c
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Abstract:
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This module implements the NT locally unique identifier services.
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Author:
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Jim Kelly (JimK) 7-June-1990
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Revision History:
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--*/
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#include "exp.h"
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//
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// Global variables needed to support locally unique IDs.
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//
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//
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// The first 1000 values are reserved for static definition. This
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// value can be increased with later releases with no adverse impact.
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//
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// N.B. The LUID source always refers to the "next" allocatable LUID.
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//
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LARGE_INTEGER ExpLuid = {1001,0};
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const LARGE_INTEGER ExpLuidIncrement = {1,0};
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#ifdef ALLOC_PRAGMA
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#pragma alloc_text(INIT, ExLuidInitialization)
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#pragma alloc_text(PAGE, NtAllocateLocallyUniqueId)
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#endif
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BOOLEAN
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ExLuidInitialization (
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VOID
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)
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/*++
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Routine Description:
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This function initializes the locally unique identifier allocation.
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NOTE: THE LUID ALLOCATION SERVICES ARE NEEDED BY SECURITY IN PHASE 0
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SYSTEM INITIALIZATION. FOR THIS REASON, LUID INITIALIZATION IS
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PERFORMED AS PART OF PHASE 0 SECURITY INITIALIZATION.
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Arguments:
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None.
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Return Value:
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A value of TRUE is returned if the initialization is successfully
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completed. Otherwise, a value of FALSE is returned.
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--*/
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{
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return TRUE;
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}
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NTSTATUS
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NtAllocateLocallyUniqueId (
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OUT PLUID Luid
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)
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/*++
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Routine Description:
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This function returns an LUID value that is unique since the system
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was last rebooted. It is unique on the system it is generated on
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only (not network wide).
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There are no restrictions on who can allocate LUIDs. The LUID space
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is large enough that this will never present a problem. If one LUID
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is allocated every 100ns, they will not be exhausted for roughly
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15,000 years (100ns * 2^63).
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Arguments:
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Luid - Supplies the address of a variable that will receive the
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new LUID.
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Return Value:
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STATUS_SUCCESS is returned if the service is successfully executed.
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STATUS_ACCESS_VIOLATION is returned if the output parameter for the
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LUID cannot be written.
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--*/
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{
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KPROCESSOR_MODE PreviousMode;
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//
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// Establish an exception handler and attempt to write the Luid
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// to the specified variable. If the write attempt fails, then return
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// the exception code as the service status. Otherwise return success
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// as the service status.
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//
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try {
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//
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// Get previous processor mode and probe argument if necessary.
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//
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PreviousMode = KeGetPreviousMode();
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if (PreviousMode != KernelMode) {
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ProbeForWriteSmallStructure((PVOID)Luid, sizeof(LUID), sizeof(ULONG));
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}
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//
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// Allocate and store a locally unique Id.
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//
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ExAllocateLocallyUniqueId(Luid);
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} except (ExSystemExceptionFilter()) {
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return GetExceptionCode();
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}
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return STATUS_SUCCESS;
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}
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