DbgkCreateThread
首先我们需要替换的是 rdmsr, wrmsr替换掉系统的sysenter跳转地址. 这样整个SSDT表函数都处于被我们的监控当中.
一个新的进程创建线程的时候就会调用到DbgkCreateThread.DbgkCreateThread可以发出两种消息, 一种进程创建,和线程创建消息.
当然, ntdll.dll的消息也在此列.DbgkCreateThread函数内部主要是判断进程是否有PSF_CREATE_REPORTED_BIT标记, 如果有那么就发送进程创建消息, 如果没有那么就发送线程创建消息, 他们都会调用到 DbgkpSendApiMessage 函数.
DbgkpSendApiMessage函数内部做的事情也不多. 主要是挂起线程和恢复线程一类的事情. 然后调用了更底层的DbgkpQueueMessage函数.
DbgkpQueueMessage函数内部大体逻辑就是将消息封装好, 插入队列, 等待R3过来取. 差不多就是这些.下面的代码是ReactOS的代码.
VOID
NTAPI
DbgkCreateThread(IN PETHREAD Thread,
IN PVOID StartAddress)
{
PEPROCESS Process = PsGetCurrentProcess();
ULONG ProcessFlags;
IMAGE_INFO ImageInfo;
PIMAGE_NT_HEADERS NtHeader;
POBJECT_NAME_INFORMATION ModuleName;
UNICODE_STRING NtDllName;
NTSTATUS Status;
PVOID DebugPort;
DBGKM_MSG ApiMessage;
PDBGKM_CREATE_THREAD CreateThread = &ApiMessage.CreateThread;
PDBGKM_CREATE_PROCESS CreateProcess = &ApiMessage.CreateProcess;
PDBGKM_LOAD_DLL LoadDll = &ApiMessage.LoadDll;
OBJECT_ATTRIBUTES ObjectAttributes;
IO_STATUS_BLOCK IoStatusBlock;
PTEB Teb;
PAGED_CODE();
/* Sanity check */
ASSERT(Thread == PsGetCurrentThread());
//
// 获取是否要调用LoadImageNotifyRoutines标记
//
ProcessFlags = PspSetProcessFlag(Process,
PSF_CREATE_REPORTED_BIT |
PSF_IMAGE_NOTIFY_DONE_BIT);
//
// 如果进程标记中有设置PSF_IMAGE_NOTIFY_DONE_BIT 并且系统中开启了LoadImageNotifyRoutines服务
// 这个if 和调试没有关系, 不管.
//
if (!(ProcessFlags & PSF_IMAGE_NOTIFY_DONE_BIT) && (PsImageNotifyEnabled))
{
/* It hasn't.. set up the image info for the process */
ImageInfo.Properties = 0;
ImageInfo.ImageAddressingMode = IMAGE_ADDRESSING_MODE_32BIT;
ImageInfo.ImageBase = Process->SectionBaseAddress;
ImageInfo.ImageSize = 0;
ImageInfo.ImageSelector = 0;
ImageInfo.ImageSectionNumber = 0;
/* Get the NT Headers */
NtHeader = RtlImageNtHeader(Process->SectionBaseAddress);
if (NtHeader)
{
/* Set image size */
ImageInfo.ImageSize = NtHeader->OptionalHeader.SizeOfImage;
}
/* Get the image name */
Status = MmGetFileNameForSection(Process->SectionObject, &ModuleName);
if (NT_SUCCESS(Status))
{
/* Call the notify routines and free the name */
PspRunLoadImageNotifyRoutines(&ModuleName->Name,
Process->UniqueProcessId,
&ImageInfo);
ExFreePool(ModuleName);
}
else
{
/* Call the notify routines */
PspRunLoadImageNotifyRoutines(NULL,
Process->UniqueProcessId,
&ImageInfo);
}
/* Setup the info for ntdll.dll */
ImageInfo.Properties = 0;
ImageInfo.ImageAddressingMode = IMAGE_ADDRESSING_MODE_32BIT;
ImageInfo.ImageBase = PspSystemDllBase;
ImageInfo.ImageSize = 0;
ImageInfo.ImageSelector = 0;
ImageInfo.ImageSectionNumber = 0;
/* Get the NT Headers */
NtHeader = RtlImageNtHeader(PspSystemDllBase);
if (NtHeader)
{
/* Set image size */
ImageInfo.ImageSize = NtHeader->OptionalHeader.SizeOfImage;
}
/* Call the notify routines */
RtlInitUnicodeString(&NtDllName,
L"\\SystemRoot\\System32\\ntdll.dll");
PspRunLoadImageNotifyRoutines(&NtDllName,
Process->UniqueProcessId,
&ImageInfo);
}
//
// 这里才真的关于调试部分的代码
//
DebugPort = Process->DebugPort;
if (!DebugPort) return;
//
// 如果调试设置了创建进程通知消息
//
if (!(ProcessFlags & PSF_CREATE_REPORTED_BIT))
{
//
// CreateProcess 是R0这边传递调试消息的主要结构. 既然是创建进程
// 那么线程当然都是空了
//
CreateProcess->InitialThread.SubSystemKey = 0;
CreateProcess->InitialThread.StartAddress = NULL;
//
// 填写新进程的句柄
//
CreateProcess->SubSystemKey = 0;
CreateProcess->FileHandle = DbgkpSectionToFileHandle(Process->
SectionObject);
//
// 其他一些信息
//
CreateProcess->BaseOfImage = Process->SectionBaseAddress;
CreateProcess->DebugInfoFileOffset = 0;
CreateProcess->DebugInfoSize = 0;
//
// 这些信息其实也不重要, 程序入口, 符号表的地址和数量
//
NtHeader = RtlImageNtHeader(Process->SectionBaseAddress);
if (NtHeader)
{
//
// 根据PE信息获取入口
//
CreateProcess->InitialThread.StartAddress =
(PVOID)((ULONG_PTR)NtHeader->OptionalHeader.ImageBase +
NtHeader->OptionalHeader.AddressOfEntryPoint);
//
// 获取调试信息表地址
//
CreateProcess->DebugInfoFileOffset = NtHeader->FileHeader.
PointerToSymbolTable;
//
// 获取调试信息的数量
//
CreateProcess->DebugInfoSize = NtHeader->FileHeader.
NumberOfSymbols;
}
// 这边开始设置
ApiMessage.h.u1.Length = sizeof(DBGKM_MSG) << 16 |
(8 + sizeof(DBGKM_CREATE_PROCESS));
ApiMessage.h.u2.ZeroInit = 0;
ApiMessage.h.u2.s2.Type = LPC_DEBUG_EVENT;
ApiMessage.ApiNumber = DbgKmCreateProcessApi;
//
// 这个函数是内核里面分发调试消息的主要函数了, 后面一个参数表示
// 是否要冻结进程的所有线程
//
DbgkpSendApiMessage(&ApiMessage, FALSE);
//
// 内核这边其实会给R3关闭句柄, 所以R3那边其实不用操心的
//
ObCloseHandle(CreateProcess->FileHandle, KernelMode);
//
// 我们看到, 其实创建进程的时候, 默认就会发送nt.dll的LoadDll消息
//
LoadDll->BaseOfDll = PspSystemDllBase;
LoadDll->DebugInfoFileOffset = 0;
LoadDll->DebugInfoSize = 0;
LoadDll->NamePointer = NULL;
//
// 获取nt.dll的调试符号偏移和大小. PspSystemDllBase真神奇
//
NtHeader = RtlImageNtHeader(PspSystemDllBase);
if (NtHeader)
{
/* Fill out debug information */
LoadDll->DebugInfoFileOffset = NtHeader->
FileHeader.PointerToSymbolTable;
LoadDll->DebugInfoSize = NtHeader->FileHeader.NumberOfSymbols;
}
//
// 保存一点nt.dll的信息
//
Teb = Thread->Tcb.Teb;
if (Teb)
{
/* Copy the system library name and link to it */
wcsncpy(Teb->StaticUnicodeBuffer,
L"ntdll.dll",
sizeof(Teb->StaticUnicodeBuffer) / sizeof(WCHAR));
Teb->NtTib.ArbitraryUserPointer = Teb->StaticUnicodeBuffer;
/* Return it in the debug event as well */
LoadDll->NamePointer = &Teb->NtTib.ArbitraryUserPointer;
}
//
// 获取nt.dll的句柄
//
InitializeObjectAttributes(&ObjectAttributes,
&PsNtDllPathName,
OBJ_CASE_INSENSITIVE |
OBJ_KERNEL_HANDLE |
OBJ_FORCE_ACCESS_CHECK,
NULL,
NULL);
Status = ZwOpenFile(&LoadDll->FileHandle,
GENERIC_READ | SYNCHRONIZE,
&ObjectAttributes,
&IoStatusBlock,
FILE_SHARE_DELETE |
FILE_SHARE_READ |
FILE_SHARE_WRITE,
FILE_SYNCHRONOUS_IO_NONALERT);
if (NT_SUCCESS(Status))
{
//
// 句柄也有了. 有酒有肉了. 可以发送DLL加载消息了
//
ApiMessage.h.u1.Length = sizeof(DBGKM_MSG) << 16 |
(8 + sizeof(DBGKM_LOAD_DLL));
ApiMessage.h.u2.ZeroInit = 0;
ApiMessage.h.u2.s2.Type = LPC_DEBUG_EVENT;
ApiMessage.ApiNumber = DbgKmLoadDllApi;
/* Send the message */
DbgkpSendApiMessage(&ApiMessage, TRUE);
//
// 同样的, R3不需要关闭句柄, 以前真是纠结啊.
//
ObCloseHandle(LoadDll->FileHandle, KernelMode);
}
}
else
{
//
// 如果不是首次创建进程, 那么也好办, 直接发送线程创建消息就可以了
//
CreateThread->SubSystemKey = 0;
CreateThread->StartAddress = StartAddress;
/* Setup the API Message */
ApiMessage.h.u1.Length = sizeof(DBGKM_MSG) << 16 |
(8 + sizeof(DBGKM_CREATE_THREAD));
ApiMessage.h.u2.ZeroInit = 0;
ApiMessage.h.u2.s2.Type = LPC_DEBUG_EVENT;
ApiMessage.ApiNumber = DbgKmCreateThreadApi;
/* Send the message */
DbgkpSendApiMessage(&ApiMessage, TRUE);
}
}
NTSTATUS
NTAPI
DbgkpSendApiMessage(IN OUT PDBGKM_MSG ApiMsg,
IN BOOLEAN SuspendProcess)
{
NTSTATUS Status;
BOOLEAN Suspended = FALSE;
PAGED_CODE();
// 看看是否需要挂起整个线程.
if (SuspendProcess)
{
Suspended = DbgkpSuspendProcess();
}
//
// 将调试包设置成忙状态
//
ApiMsg->ReturnedStatus = STATUS_PENDING;
//
// 设置进程的PSF_CREATE_REPORTED_BIT位
//
PspSetProcessFlag(PsGetCurrentProcess(), PSF_CREATE_REPORTED_BIT);
//
// 将调试消息插入队列中
//
Status = DbgkpQueueMessage(PsGetCurrentProcess(),
PsGetCurrentThread(),
ApiMsg,
0,
NULL);
//
// 刷新指令缓存
//
ZwFlushInstructionCache(NtCurrentProcess(), NULL, 0);
//
// 如果挂起了线程, 那么还需要重新恢复线程运行
//
if (Suspended)
{
DbgkpResumeProcess();
}
return Status;
}
NTSTATUS
NTAPI
DbgkpQueueMessage(IN PEPROCESS Process,
IN PETHREAD Thread,
IN PDBGKM_MSG Message,
IN ULONG Flags,
IN PDEBUG_OBJECT TargetObject OPTIONAL)
{
PDEBUG_EVENT DebugEvent;
DEBUG_EVENT LocalDebugEvent;
PDEBUG_OBJECT DebugObject;
NTSTATUS Status;
BOOLEAN NewEvent;
PAGED_CODE();
//
// 检测是否需要分配调试事件句柄, 根据调试, 从来就没有进来过. 忽略
//
NewEvent = (Flags & DEBUG_EVENT_NOWAIT) ? TRUE : FALSE;
if (NewEvent)
{
/* Allocate it */
DebugEvent = ExAllocatePoolWithTag(NonPagedPool,
sizeof(DEBUG_EVENT),
'EgbD');
if (!DebugEvent) return STATUS_INSUFFICIENT_RESOURCES;
/* Set flags */
DebugEvent->Flags = Flags | DEBUG_EVENT_INACTIVE;
/* Reference the thread and process */
ObReferenceObject(Thread);
ObReferenceObject(Process);
/* Set the current thread */
DebugEvent->BackoutThread = PsGetCurrentThread();
/* Set the debug object */
DebugObject = TargetObject;
}
else
{
/* Use the debug event on the stack */
DebugEvent = &LocalDebugEvent;
DebugEvent->Flags = Flags;
//
// 获取调试消息发送自旋锁
//
ExAcquireFastMutex(&DbgkpProcessDebugPortMutex);
// 调试对象
DebugObject = Process->DebugPort;
//
// 这里检测是否要跳过某些消息, 显然是没有什么用的.
//
switch (Message->ApiNumber)
{
/* Process or thread creation */
case DbgKmCreateThreadApi:
case DbgKmCreateProcessApi:
/* Make sure we're not skipping creation messages */
if (Thread->SkipCreationMsg) DebugObject = NULL;
break;
/* Process or thread exit */
case DbgKmExitThreadApi:
case DbgKmExitProcessApi:
/* Make sure we're not skipping exit messages */
if (Thread->SkipTerminationMsg) DebugObject = NULL;
/* No special handling for other messages */
default:
break;
}
}
//
// 初始化调试信息发送完成事件
//
KeInitializeEvent(&DebugEvent->ContinueEvent, SynchronizationEvent, FALSE);
DebugEvent->Process = Process;
DebugEvent->Thread = Thread;
DebugEvent->ApiMsg = *Message;
DebugEvent->ClientId = Thread->Cid;
//
// 检测调试端口是否正常
//
if (!DebugObject)
{
/* Fail */
Status = STATUS_PORT_NOT_SET;
}
else
{
//
// 这是进程内调试对象获取的自旋锁
//
ExAcquireFastMutex(&DebugObject->Mutex);
//
// 检测调试器目前是否激活
//
if (!DebugObject->DebuggerInactive)
{
//
// 插入进程的调试端口事件链表
//
InsertTailList(&DebugObject->EventList, &DebugEvent->EventList);
//
// 事件置位, 这是干什么用的事件呢?
//
if (!NewEvent)
{
/* Signal it */
KeSetEvent(&DebugObject->EventsPresent,
IO_NO_INCREMENT,
FALSE);
}
/* Set success */
Status = STATUS_SUCCESS;
}
else
{
//
// 没有调试
//
Status = STATUS_DEBUGGER_INACTIVE;
}
/* Release the object lock */
ExReleaseFastMutex(&DebugObject->Mutex);
}
/* Check if we had acquired the port lock */
if (!NewEvent)
{
//
// 这里释放快速互斥锁
//
ExReleaseFastMutex(&DbgkpProcessDebugPortMutex);
/* Check if we got here through success */
if (NT_SUCCESS(Status))
{
//
// 等待R3那边过来取消息
//
KeWaitForSingleObject(&DebugEvent->ContinueEvent,
Executive,
KernelMode,
FALSE,
NULL);
/* Copy API Message back */
*Message = DebugEvent->ApiMsg;
/* Set return status */
Status = DebugEvent->Status;
}
}
else
{
/* Check if we failed */
if (!NT_SUCCESS(Status))
{
/* Dereference the process and thread */
ObDereferenceObject(Thread);
ObDereferenceObject(Process);
/* Free the debug event */
ExFreePool(DebugEvent);
}
}
return Status;
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