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CORE-17470 + KdpDebugLogInit: Add resources cleanup in failure code paths. Fix, in an NT-compatible manner, how (and when) the KD/KDBG BootPhase >=2 initialization steps are performed. These are necessary for any functionality KDBG needs, that would depend on the NT I/O Manager and the storage and filesystem stacks to be running. This includes, creating the debug log file, and for KDBG, loading its KDBinit initialization file. As a result, file debug logging is fixed. The old ReactOS-specific (NT-incompatible) callback we did in the middle of IoInitSystem() is removed, in favor of a runtime mechanism that should work on Windows as well. The idea for this new mechanism is loosely inspired by the TDL4 rootkit, see http://blog.w4kfu.com/public/tdl4_article/draft_tdl4article.html but contrary to it, a specific hook is used instead, as well as the technique of driver reinitialization: https://web.archive.org/web/20211021050515/https://driverentry.com.br/en/blog/?p=261 Its rationale is as follows: We want to be able to perform I/O-related initialization (starting a logger thread for file log debugging, loading KDBinit file for KDBG, etc.). A good place for this would be as early as possible, once the I/O Manager has started the storage and the boot filesystem drivers. Here is an overview of the initialization steps of the NT Kernel and Executive: ---- KiSystemStartup(KeLoaderBlock) if (Cpu == 0) KdInitSystem(0, KeLoaderBlock); KiSwitchToBootStack() -> KiSystemStartupBootStack() -> KiInitializeKernel() -> ExpInitializeExecutive(Cpu, KeLoaderBlock) (NOTE: Any unexpected debugger break will call KdInitSystem(0, NULL); ) KdInitSystem(0, LoaderBlock) -> KdDebuggerInitialize0(LoaderBlock); ExpInitializeExecutive(Cpu == 0): ExpInitializationPhase = 0; HalInitSystem(0, KeLoaderBlock); <-- Sets HalInitPnpDriver callback. ... PsInitSystem(LoaderBlock) PsCreateSystemThread(Phase1Initialization) Phase1Initialization(Discard): ExpInitializationPhase = 1; HalInitSystem(1, KeLoaderBlock); ... Early initialization of Ob, Ex, Ke. KdInitSystem(1, KeLoaderBlock); ... KdDebuggerInitialize1(LoaderBlock); ... IoInitSystem(LoaderBlock); ... ---- As we can see, KdDebuggerInitialize1() is the last KD initialization routine the kernel calls, and is called *before* the I/O Manager starts. Thus, direct Nt/ZwCreateFile ... calls done there would fail. Also, we want to do the I/O initialization as soon as possible. There does not seem to be any exported way to be notified about the I/O manager initialization steps... that is, unless we somehow become a driver and insert ourselves in the flow! Since we are not a regular driver, we need to invoke IoCreateDriver() to create one. However, remember that we are currently running *before* IoInitSystem(), the I/O subsystem is not initialized yet. Due to this, calling IoCreateDriver(), much like any other IO functions, would lead to a crash, because it calls ObCreateObject(..., IoDriverObjectType, ...), and IoDriverObjectType is non-initialized yet (it's NULL). The chosen solution is to hook a "known" exported callback: namely, the HalInitPnpDriver() callback (it initializes the "HAL Root Bus Driver"). It is set very early on by the HAL via the HalInitSystem(0, ...) call, and is called early on by IoInitSystem() before any driver is loaded, but after the I/O Manager has been minimally set up so that new drivers can be created. When the hook: KdpInitDriver() is called, we create our driver with IoCreateDriver(), specifying its entrypoint KdpDriverEntry(), then restore and call the original HalInitPnpDriver() callback. Another possible unexplored alternative, could be to insert ourselves in the KeLoaderBlock->LoadOrderListHead boot modules list, or in the KeLoaderBlock->BootDriverListHead boot-driver list. (Note that while we may be able to do this, because boot-drivers are resident in memory, much like we are, we cannot insert ourselves in the system-driver list however, since those drivers are expected to come from PE image files.) Once the KdpDriverEntry() driver entrypoint is called, we register KdpDriverReinit() for re-initialization with the I/O Manager, in order to provide more initialization points. KdpDriverReinit() calls the KD providers at BootPhase >= 2, and schedules further reinitializations (at most 3 more) if any of the providers request so. |
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| .. | ||
| iomgr | ||
| pnpmgr | ||
| debug.c | ||
| pnpio.h | ||