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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2015-2026 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include "interlocked.h"
#include "containers.h"
#include "device.h"
#include "messages.h"
#include "undocumented.h"
#include "nsi.h"
#include <netiodef.h>
#include <netioapi.h>
static DRIVER_OBJECT *DriverObj;
static HANDLE IpInterfaceNotifier;
static DEVICE_OBJECT *FilterDevice, *NsiDevice;
static EX_RUNDOWN_REF FilterRundown;
static DRIVER_DISPATCH *PriorDispatch[IRP_MJ_MAXIMUM_FUNCTION + 1];
static LIST_ENTRY DeviceList;
static EX_PUSH_LOCK DeviceListLock, FilterLock;
static VOID
IpInterfaceChangeNotification(
_In_opt_ PVOID CallerContext,
_In_opt_ PMIB_IPINTERFACE_ROW Row,
_In_ MIB_NOTIFICATION_TYPE NotificationType)
{
if ((NotificationType != MibAddInstance && NotificationType != MibParameterNotification) || !Row ||
(NotificationType == MibParameterNotification && (!Row->NlMtu || Row->NlMtu == ~0U)))
return;
MuAcquirePushLockShared(&DeviceListLock);
WG_DEVICE *IterWg, *Wg = NULL;
LIST_FOR_EACH_ENTRY (IterWg, &DeviceList, DeviceList)
{
if (IterWg->InterfaceLuid.Value == Row->InterfaceLuid.Value)
{
Wg = IterWg;
break;
}
}
if (!Wg)
goto cleanupDeviceListLock;
ULONG *Mtu;
if (Row->Family == AF_INET)
Mtu = &Wg->Mtu4;
else if (Row->Family == AF_INET6)
Mtu = &Wg->Mtu6;
else
goto cleanupDeviceListLock;
if (NotificationType == MibAddInstance && !*Mtu)
{
if ((!Row->NlMtu || Row->NlMtu == ~0U) && !NT_SUCCESS(GetIpInterfaceEntry(Row)))
goto cleanupDeviceListLock;
*Mtu = min(MTU_MAX, Row->NlMtu);
if (Row->NlMtu == MTU_MAX || !Row->NlMtu || Row->NlMtu == ~0U)
{
Row->SitePrefixLength = 0;
Row->NlMtu = 1500 - DATA_PACKET_MINIMUM_LENGTH;
if (NT_SUCCESS(SetIpInterfaceEntry(Row)))
*Mtu = min(MTU_MAX, Row->NlMtu);
}
}
else if (NotificationType == MibParameterNotification)
*Mtu = min(MTU_MAX, Row->NlMtu);
cleanupDeviceListLock:
MuReleasePushLockShared(&DeviceListLock);
}
static_assert(
FIELD_SIZE(MIB_IPINTERFACE_ROW, NlMtu) == FIELD_SIZE(NSI_IP_INTERFACE_RW, NlMtu) &&
FIELD_SIZE(MIB_IPINTERFACE_ROW, NlMtu) == FIELD_SIZE(NSI_IP_SUBINTERFACE_RW, NlMtu),
"NlMtu sizes must match across MIB_IPINTERFACE_ROW, NSI_IP_INTERFACE_RW, and NSI_IP_SUBINTERFACE_RW");
_Success_(return)
static BOOLEAN
TryBuildMTURow(_In_ IRP *Irp, _Out_ MIB_IPINTERFACE_ROW *Row)
{
IO_STACK_LOCATION *Stack = IoGetCurrentIrpStackLocation(Irp);
if (Stack->MajorFunction != IRP_MJ_DEVICE_CONTROL ||
Stack->Parameters.DeviceIoControl.IoControlCode != IOCTL_NSI_SET_ALL_PARAMETERS)
return FALSE;
NPI_MODULEID ModuleId = { 0 };
__try
{
NSI_SET_ALL_PARAMETERS Params;
UCHAR *UserBuffer = Stack->Parameters.DeviceIoControl.Type3InputBuffer;
ULONG Len = Stack->Parameters.DeviceIoControl.InputBufferLength;
BOOLEAN ShouldProbe = Irp->RequestorMode != KernelMode;
#ifdef _WIN64
if (IoIs32bitProcess(Irp))
{
NSI_SET_ALL_PARAMETERS_32 Params32;
if (Len < sizeof(Params32))
return FALSE;
if (ShouldProbe)
ProbeForRead(UserBuffer, sizeof(Params32), 1);
RtlCopyMemory(&Params32, UserBuffer, sizeof(Params32));
RtlZeroMemory(&Params, sizeof(Params));
Params.ModuleId = (PVOID)(ULONG_PTR)Params32.ModuleId;
Params.ObjectIndex = Params32.ObjectIndex;
Params.KeyStruct = (PVOID)(ULONG_PTR)Params32.KeyStruct;
Params.KeyStructLength = Params32.KeyStructLength;
Params.RwParameterStruct = (PVOID)(ULONG_PTR)Params32.RwParameterStruct;
Params.RwParameterStructLength = Params32.RwParameterStructLength;
}
else
#endif
{
if (Len < sizeof(Params))
return FALSE;
if (ShouldProbe)
ProbeForRead(UserBuffer, sizeof(Params), 1);
RtlCopyMemory(&Params, UserBuffer, sizeof(Params));
}
if (Params.KeyStructLength < sizeof(Row->InterfaceLuid))
return FALSE;
ULONG MtuOffset;
if ((ULONG)Params.ObjectIndex == NlInterfaceObject &&
Params.RwParameterStructLength >= FIELD_OFFSET(NSI_IP_INTERFACE_RW, NlMtu) + FIELD_SIZE(NSI_IP_INTERFACE_RW, NlMtu))
MtuOffset = FIELD_OFFSET(NSI_IP_INTERFACE_RW, NlMtu);
else if ((ULONG)Params.ObjectIndex == NlSubInterfaceObject &&
Params.RwParameterStructLength >= FIELD_OFFSET(NSI_IP_SUBINTERFACE_RW, NlMtu) + FIELD_SIZE(NSI_IP_SUBINTERFACE_RW, NlMtu))
MtuOffset = FIELD_OFFSET(NSI_IP_SUBINTERFACE_RW, NlMtu);
else
return FALSE;
if (ShouldProbe)
ProbeForRead(Params.ModuleId, sizeof(ModuleId), 1);
RtlCopyMemory(&ModuleId, Params.ModuleId, sizeof(ModuleId));
if (ShouldProbe)
ProbeForRead(Params.KeyStruct, sizeof(Row->InterfaceLuid), 1);
RtlCopyMemory(&Row->InterfaceLuid, Params.KeyStruct, sizeof(Row->InterfaceLuid));
if (ShouldProbe)
ProbeForRead((UCHAR *)Params.RwParameterStruct + MtuOffset, sizeof(Row->NlMtu), 1);
RtlCopyMemory(&Row->NlMtu, (UCHAR *)Params.RwParameterStruct + MtuOffset, sizeof(Row->NlMtu));
}
__except (EXCEPTION_EXECUTE_HANDLER) { return FALSE; }
if (!Row->NlMtu || Row->NlMtu == ~0U)
return FALSE;
if (RtlEqualMemory(&NPI_MS_IPV4_MODULEID, &ModuleId, sizeof(ModuleId)))
Row->Family = AF_INET;
else if (RtlEqualMemory(&NPI_MS_IPV6_MODULEID, &ModuleId, sizeof(ModuleId)))
Row->Family = AF_INET6;
else
return FALSE;
return TRUE;
}
static DRIVER_DISPATCH_PAGED FilterDispatch;
_Use_decl_annotations_
static NTSTATUS
FilterDispatch(DEVICE_OBJECT *DeviceObject, IRP *Irp)
{
FILE_OBJECT *FileObject;
if (DeviceObject->DeviceExtension) /* NDIS devices always have an extension. */
return PriorDispatch[IoGetCurrentIrpStackLocation(Irp)->MajorFunction](DeviceObject, Irp);
if (!ExAcquireRundownProtection(&FilterRundown))
goto bypassFilter;
if (DeviceObject != ReadPointerNoFence(&FilterDevice))
{
ExReleaseRundownProtection(&FilterRundown);
goto bypassFilter;
}
MIB_IPINTERFACE_ROW Row = { 0 };
BOOLEAN ValidMTURow = TryBuildMTURow(Irp, &Row);
IoSkipCurrentIrpStackLocation(Irp);
NTSTATUS Status = IoCallDriver(NsiDevice, Irp);
if (ValidMTURow && NT_SUCCESS(Status) && Status != STATUS_PENDING)
IpInterfaceChangeNotification(NULL, &Row, MibParameterNotification);
ExReleaseRundownProtection(&FilterRundown);
return Status;
bypassFilter:
FileObject = IoGetCurrentIrpStackLocation(Irp)->FileObject;
if (FileObject && FileObject->DeviceObject)
{
IoSkipCurrentIrpStackLocation(Irp);
return IoCallDriver(FileObject->DeviceObject, Irp);
}
Irp->IoStatus.Status = STATUS_DEVICE_REMOVED;
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return STATUS_DEVICE_REMOVED;
}
static NTSTATUS
Attach(VOID)
{
NTSTATUS Status =
NotifyIpInterfaceChange(AF_UNSPEC, IpInterfaceChangeNotification, NULL, FALSE, &IpInterfaceNotifier);
if (!NT_SUCCESS(Status))
return Status;
UNICODE_STRING NsiName = RTL_CONSTANT_STRING(L"\\Device\\Nsi");
PFILE_OBJECT NsiFileObject;
Status = IoGetDeviceObjectPointer(&NsiName, FILE_READ_ATTRIBUTES, &NsiFileObject, &NsiDevice);
if (!NT_SUCCESS(Status))
goto cleanupIpInterfaceNotifier;
Status = IoCreateDevice(DriverObj, 0, NULL, NsiDevice->DeviceType, 0, FALSE, &FilterDevice);
if (!NT_SUCCESS(Status))
goto cleanupFileObject;
FilterDevice->Flags |= NsiDevice->Flags & (DO_BUFFERED_IO | DO_DIRECT_IO | DO_POWER_PAGABLE);
ExReInitializeRundownProtection(&FilterRundown);
PDEVICE_OBJECT Attached = IoAttachDeviceToDeviceStack(FilterDevice, NsiDevice);
if (!Attached)
{
Status = STATUS_DEVICE_REMOVED;
goto cleanupRundown;
}
NsiDevice = Attached;
FilterDevice->Flags &= ~DO_DEVICE_INITIALIZING;
ObReferenceObject(NsiDevice);
ObDereferenceObject(NsiFileObject);
return STATUS_SUCCESS;
cleanupRundown:
ExWaitForRundownProtectionRelease(&FilterRundown);
{
DEVICE_OBJECT *FilterDeviceToDelete = FilterDevice;
WritePointerNoFence(&FilterDevice, NULL);
IoDeleteDevice(FilterDeviceToDelete);
}
cleanupFileObject:
ObDereferenceObject(NsiFileObject);
cleanupIpInterfaceNotifier:
CancelMibChangeNotify2(IpInterfaceNotifier);
return Status;
}
static VOID
Detach(VOID)
{
CancelMibChangeNotify2(IpInterfaceNotifier);
IoDetachDevice(NsiDevice);
ExWaitForRundownProtectionRelease(&FilterRundown);
DEVICE_OBJECT *FilterDeviceToDelete = FilterDevice;
WritePointerNoFence(&FilterDevice, NULL);
IoDeleteDevice(FilterDeviceToDelete);
ObDereferenceObject(NsiDevice);
}
#ifdef ALLOC_PRAGMA
# pragma alloc_text(INIT, NsiDriverEntry)
#endif
_Use_decl_annotations_
VOID
NsiDriverEntry(DRIVER_OBJECT *DriverObject)
{
DriverObj = DriverObject;
InitializeListHead(&DeviceList);
MuInitializePushLock(&DeviceListLock);
MuInitializePushLock(&FilterLock);
ExInitializeRundownProtection(&FilterRundown);
ExWaitForRundownProtectionRelease(&FilterRundown);
for (ULONG i = 0; i <= IRP_MJ_MAXIMUM_FUNCTION; ++i)
{
PriorDispatch[i] = DriverObject->MajorFunction[i];
DriverObject->MajorFunction[i] = FilterDispatch;
}
}
_Use_decl_annotations_
NTSTATUS
NsiActivate(WG_DEVICE *Wg)
{
NTSTATUS Status;
MuAcquirePushLockExclusive(&FilterLock);
if (IsListEmpty(&DeviceList))
{
Status = Attach();
if (!NT_SUCCESS(Status))
{
MuReleasePushLockExclusive(&FilterLock);
return Status;
}
}
MuAcquirePushLockExclusive(&DeviceListLock);
InsertTailList(&DeviceList, &Wg->DeviceList);
MuReleasePushLockExclusive(&DeviceListLock);
MuReleasePushLockExclusive(&FilterLock);
return STATUS_SUCCESS;
}
_Use_decl_annotations_
VOID
NsiDeactivate(WG_DEVICE *Wg)
{
MuAcquirePushLockExclusive(&FilterLock);
MuAcquirePushLockExclusive(&DeviceListLock);
RemoveEntryList(&Wg->DeviceList);
BOOLEAN NowEmpty = IsListEmpty(&DeviceList);
MuReleasePushLockExclusive(&DeviceListLock);
if (NowEmpty)
Detach();
MuReleasePushLockExclusive(&FilterLock);
}
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