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文件过滤加密的源代码   返回

//过滤读

NTSTATUS SfRead(__in PDEVICE_OBJECT DeviceObject, __in PIRP Irp)

{

PIO_STACK_LOCATION irp_stack;

BOOLEAN is_crypt;

NTSTATUS status;

PSFILTER_DEVICE_EXTENSION devExt;

PAGED_CODE();

ASSERT(!IS_MY_CONTROL_DEVICE_OBJECT( DeviceObject ));

ASSERT(IS_MY_DEVICE_OBJECT( DeviceObject ));

devExt = (PSFILTER_DEVICE_EXTENSION)(DeviceObject->DeviceExtension);

if(Irp->Flags & (IRP_NOCACHE | IRP_PAGING_IO | IRP_SYNCHRONOUS_PAGING_IO))

{

irp_stack = IoGetCurrentIrpStackLocation( Irp );

is_crypt = IsMyCryptFile(irp_stack->FileObject);

if(is_crypt) //是我的加密文件

{

//设置完成例程

IoCopyCurrentIrpStackLocationToNext( Irp );

IoSetCompletionRoutine(Irp, SfReadCompletion, 0, TRUE, FALSE, FALSE);

//调用原来的驱动

return IoCallDriver(devExt->AttachedToDeviceObject, Irp);

}

}

//非加密文件

IoSkipCurrentIrpStackLocation(Irp);

return IoCallDriver(devExt->AttachedToDeviceObject, Irp);

}

//读操作的完成例程

NTSTATUS SfReadCompletion(__in PDEVICE_OBJECT DeviceObject, __in PIRP Irp, __in PVOID Context)

{

ULONG length; //长度

PUCHAR buffer; //缓冲区

ULONG i;

PIO_STACK_LOCATION irp_stack;

irp_stack = IoGetCurrentIrpStackLocation( Irp );

ShowUnicodeString(&(irp_stack->FileObject->FileName));

DbgPrint("SfReadCompletion 读文件解密");

length = Irp->IoStatus.Information;

buffer = MmGetSystemAddressForMdlSafe(Irp->MdlAddress, NormalPagePriority);

for(i = 0; i < length; i++)

{

buffer[i] = buffer[i] - 17; //解密

}

return STATUS_SUCCESS;

}

//过滤写

NTSTATUS SfWrite(__in PDEVICE_OBJECT DeviceObject, __in PIRP Irp)

{

PIO_STACK_LOCATION irp_stack;

BOOLEAN is_crypt;

NTSTATUS status;

PSFILTER_DEVICE_EXTENSION devExt;

PAGED_CODE();

ASSERT(!IS_MY_CONTROL_DEVICE_OBJECT( DeviceObject ));

ASSERT(IS_MY_DEVICE_OBJECT( DeviceObject ));

devExt = (PSFILTER_DEVICE_EXTENSION)(DeviceObject->DeviceExtension);

if(Irp->Flags & (IRP_NOCACHE | IRP_PAGING_IO | IRP_SYNCHRONOUS_PAGING_IO))

{

irp_stack = IoGetCurrentIrpStackLocation( Irp );

is_crypt = IsMyCryptFile(irp_stack->FileObject);

if(is_crypt)

{

ULONG length; //长度

PUCHAR buffer, buffer2; //原来缓冲区和加密后缓冲区

ULONG i;

PMDL new_mdl;

length = irp_stack->Parameters.Write.Length;

buffer = MmGetSystemAddressForMdlSafe(Irp->MdlAddress, NormalPagePriority);

//分配同样大小的空间

buffer2 = (PUCHAR)ExAllocatePool(NonPagedPool, length);

if(buffer2 != 0)

{

ShowUnicodeString(&(irp_stack->FileObject->FileName));

DbgPrint("SfWrite 写文件加密");

for(i = 0; i < length; i++)

{

buffer2[i] = buffer[i] + 17; //加密

}

//设置完成例程

IoCopyCurrentIrpStackLocationToNext( Irp );

IoSetCompletionRoutine(Irp, SfWriteCompletion, Irp->MdlAddress, TRUE, TRUE, TRUE);

//替换成新的缓冲区

new_mdl = IoAllocateMdl(buffer2, length, FALSE, TRUE, NULL);

MmBuildMdlForNonPagedPool(new_mdl);

Irp->MdlAddress = new_mdl;

//调用原来的驱动

return IoCallDriver(devExt->AttachedToDeviceObject, Irp);

}

else

{

ShowUnicodeString(&(irp_stack->FileObject->FileName));

DbgPrint("SfWrite 写不能分配内存");

Irp->IoStatus.Status = STATUS_INSUFFICIENT_RESOURCES;

Irp->IoStatus.Information = 0;

IoCompleteRequest( Irp, IO_NO_INCREMENT );

return Irp->IoStatus.Status;

}

}

}

//非加密文件

IoSkipCurrentIrpStackLocation(Irp);

return IoCallDriver(devExt->AttachedToDeviceObject, Irp);

}

//写完成后就把分配的空间给删除掉

NTSTATUS SfWriteCompletion(__in PDEVICE_OBJECT DeviceObject, __in PIRP Irp, __in PVOID Context)

{

PMDL old_mdl, new_mdl;

PUCHAR buffer2; //我分配的缓冲区

PIO_STACK_LOCATION irp_stack;

irp_stack = IoGetCurrentIrpStackLocation( Irp );

ShowUnicodeString(&(irp_stack->FileObject->FileName));

DbgPrint("完成: SfWriteCompletion");

new_mdl = Irp->MdlAddress;

old_mdl = (PMDL)Context;

//还是指向原来的缓冲区

Irp->MdlAddress = old_mdl;

//删除掉我分配的缓冲区

buffer2 = MmGetSystemAddressForMdlSafe(new_mdl, NormalPagePriority);

IoFreeMdl(new_mdl);

ExFreePool(buffer2);

return STATUS_SUCCESS;

}

//文件打开的时候调用

NTSTATUS SfCreate(__in PDEVICE_OBJECT DeviceObject, __in PIRP Irp)

{

NTSTATUS status;

PSFILTER_DEVICE_EXTENSION devExt;

PAGED_CODE();

//如果不是过滤驱动设备就退出

if (IS_MY_CONTROL_DEVICE_OBJECT(DeviceObject))

{

Irp->IoStatus.Status = STATUS_SUCCESS;

Irp->IoStatus.Information = 0;

IoCompleteRequest( Irp, IO_NO_INCREMENT );

return STATUS_SUCCESS;

}

ASSERT(IS_MY_DEVICE_OBJECT( DeviceObject ));

devExt = (PSFILTER_DEVICE_EXTENSION)(DeviceObject->DeviceExtension);

//设置完成例程

IoCopyCurrentIrpStackLocationToNext( Irp );

IoSetCompletionRoutine(Irp, SfCreateCompletion, 0, TRUE, FALSE, FALSE);

//调用原来的驱动

return IoCallDriver( devExt->AttachedToDeviceObject, Irp );

}

//在打开文件的完成例程中记录文件对象

NTSTATUS SfCreateCompletion(__in PDEVICE_OBJECT DeviceObject, __in PIRP Irp, __in PVOID Context)

{

PIO_STACK_LOCATION irp_stack;

PFILE_OBJECT file_obj;

BOOLEAN is_crypt;

irp_stack = IoGetCurrentIrpStackLocation(Irp);

file_obj = irp_stack->FileObject;

is_crypt = IsMyCryptFile(file_obj);

if(is_crypt)

{

if(CcIsFileCached(file_obj))

{

ShowUnicodeString(&(file_obj->FileName));

DbgPrint("打开时清除缓存 \n");

CcPurgeCacheSection(file_obj->SectionObjectPointer, 0, 0, FALSE);

}

}

return STATUS_SUCCESS;

}

//关闭文件后的清理工作

NTSTATUS SfCleanupClose(__in PDEVICE_OBJECT DeviceObject, __in PIRP Irp)

{

NTSTATUS status;

PSFILTER_DEVICE_EXTENSION devExt;

PIO_STACK_LOCATION irp_stack;

PFILE_OBJECT file_obj;

BOOLEAN is_crypt;

PAGED_CODE();

if (IS_MY_CONTROL_DEVICE_OBJECT(DeviceObject))

{

Irp->IoStatus.Status = STATUS_SUCCESS;

Irp->IoStatus.Information = 0;

IoCompleteRequest( Irp, IO_NO_INCREMENT );

return STATUS_SUCCESS;

}

ASSERT(IS_MY_DEVICE_OBJECT( DeviceObject ));

irp_stack = IoGetCurrentIrpStackLocation(Irp);

file_obj = irp_stack->FileObject;

is_crypt = IsMyCryptFile(file_obj);

if(is_crypt)

{

if(CcIsFileCached(file_obj))

{

ShowUnicodeString(&(file_obj->FileName));

DbgPrint("关闭时清除缓存 \n");

CcPurgeCacheSection(file_obj->SectionObjectPointer, 0, 0, FALSE);

}

}

IoSkipCurrentIrpStackLocation( Irp );

devExt = (PSFILTER_DEVICE_EXTENSION)(DeviceObject->DeviceExtension);

return IoCallDriver(devExt->AttachedToDeviceObject, Irp);

}





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