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// Copyright 2015 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "snapshot/win/process_reader_win.h"
#include <string.h>
#include <winternl.h>
#include <memory>
#include "base/numerics/safe_conversions.h"
#include "base/strings/stringprintf.h"
#include "util/misc/capture_context.h"
#include "util/misc/time.h"
#include "util/win/nt_internals.h"
#include "util/win/ntstatus_logging.h"
#include "util/win/process_structs.h"
#include "util/win/scoped_handle.h"
namespace crashpad {
namespace {
// Gets a pointer to the process information structure after a given one, or
// null when iteration is complete, assuming they've been retrieved in a block
// via NtQuerySystemInformation().
template <class Traits>
process_types::SYSTEM_PROCESS_INFORMATION<Traits>* NextProcess(
process_types::SYSTEM_PROCESS_INFORMATION<Traits>* process) {
ULONG offset = process->NextEntryOffset;
if (offset == 0)
return nullptr;
return reinterpret_cast<process_types::SYSTEM_PROCESS_INFORMATION<Traits>*>(
reinterpret_cast<uint8_t*>(process) + offset);
}
//! \brief Retrieves the SYSTEM_PROCESS_INFORMATION for a given process.
//!
//! The returned pointer points into the memory block stored by \a buffer.
//! Ownership of \a buffer is transferred to the caller.
//!
//! \return Pointer to the process' data, or nullptr if it was not found or on
//! error. On error, a message will be logged.
template <class Traits>
process_types::SYSTEM_PROCESS_INFORMATION<Traits>* GetProcessInformation(
HANDLE process_handle,
std::unique_ptr<uint8_t[]>* buffer) {
ULONG buffer_size = 16384;
ULONG actual_size;
buffer->reset(new uint8_t[buffer_size]);
NTSTATUS status;
// This must be in retry loop, as we're racing with process creation on the
// system to find a buffer large enough to hold all process information.
for (int tries = 0; tries < 20; ++tries) {
status = crashpad::NtQuerySystemInformation(
SystemProcessInformation,
reinterpret_cast<void*>(buffer->get()),
buffer_size,
&actual_size);
if (status == STATUS_BUFFER_TOO_SMALL ||
status == STATUS_INFO_LENGTH_MISMATCH) {
DCHECK_GT(actual_size, buffer_size);
// Add a little extra to try to avoid an additional loop iteration. We're
// racing with system-wide process creation between here and the next call
// to NtQuerySystemInformation().
buffer_size = actual_size + 4096;
// Free the old buffer before attempting to allocate a new one.
buffer->reset();
buffer->reset(new uint8_t[buffer_size]);
} else {
break;
}
}
if (!NT_SUCCESS(status)) {
NTSTATUS_LOG(ERROR, status) << "NtQuerySystemInformation";
return nullptr;
}
DCHECK_LE(actual_size, buffer_size);
process_types::SYSTEM_PROCESS_INFORMATION<Traits>* process =
reinterpret_cast<process_types::SYSTEM_PROCESS_INFORMATION<Traits>*>(
buffer->get());
DWORD process_id = GetProcessId(process_handle);
for (;;) {
if (process->UniqueProcessId == process_id)
return process;
process = NextProcess(process);
if (!process)
break;
}
LOG(ERROR) << "process " << process_id << " not found";
return nullptr;
}
template <class Traits>
HANDLE OpenThread(
const process_types::SYSTEM_THREAD_INFORMATION<Traits>& thread_info) {
HANDLE handle;
ACCESS_MASK query_access =
THREAD_GET_CONTEXT | THREAD_SUSPEND_RESUME | THREAD_QUERY_INFORMATION;
OBJECT_ATTRIBUTES object_attributes;
InitializeObjectAttributes(&object_attributes, nullptr, 0, nullptr, nullptr);
NTSTATUS status = crashpad::NtOpenThread(
&handle, query_access, &object_attributes, &thread_info.ClientId);
if (!NT_SUCCESS(status)) {
NTSTATUS_LOG(ERROR, status) << "NtOpenThread";
return nullptr;
}
return handle;
}
// It's necessary to suspend the thread to grab CONTEXT. SuspendThread has a
// side-effect of returning the SuspendCount of the thread on success, so we
// fill out these two pieces of semi-unrelated data in the same function.
template <class Traits>
bool FillThreadContextAndSuspendCount(HANDLE thread_handle,
ProcessReaderWin::Thread* thread,
ProcessSuspensionState suspension_state,
bool is_64_reading_32) {
// Don't suspend the thread if it's this thread. This is really only for test
// binaries, as we won't be walking ourselves, in general.
bool is_current_thread = thread->id ==
reinterpret_cast<process_types::TEB<Traits>*>(
NtCurrentTeb())->ClientId.UniqueThread;
if (is_current_thread) {
DCHECK(suspension_state == ProcessSuspensionState::kRunning);
thread->suspend_count = 0;
DCHECK(!is_64_reading_32);
CaptureContext(&thread->context.native);
} else {
DWORD previous_suspend_count = SuspendThread(thread_handle);
if (previous_suspend_count == static_cast<DWORD>(-1)) {
PLOG(ERROR) << "SuspendThread";
return false;
}
DCHECK(previous_suspend_count > 0 ||
suspension_state == ProcessSuspensionState::kRunning);
thread->suspend_count =
previous_suspend_count -
(suspension_state == ProcessSuspensionState::kSuspended ? 1 : 0);
memset(&thread->context, 0, sizeof(thread->context));
#if defined(ARCH_CPU_32_BITS)
const bool is_native = true;
#elif defined(ARCH_CPU_64_BITS)
const bool is_native = !is_64_reading_32;
if (is_64_reading_32) {
thread->context.wow64.ContextFlags = CONTEXT_ALL;
if (!Wow64GetThreadContext(thread_handle, &thread->context.wow64)) {
PLOG(ERROR) << "Wow64GetThreadContext";
return false;
}
}
#endif
if (is_native) {
thread->context.native.ContextFlags = CONTEXT_ALL;
if (!GetThreadContext(thread_handle, &thread->context.native)) {
PLOG(ERROR) << "GetThreadContext";
return false;
}
}
if (!ResumeThread(thread_handle)) {
PLOG(ERROR) << "ResumeThread";
return false;
}
}
return true;
}
} // namespace
ProcessReaderWin::Thread::Thread()
: context(),
id(0),
teb_address(0),
teb_size(0),
stack_region_address(0),
stack_region_size(0),
suspend_count(0),
priority_class(0),
priority(0) {
}
ProcessReaderWin::ProcessReaderWin()
: process_(INVALID_HANDLE_VALUE),
process_info_(),
process_memory_(),
threads_(),
modules_(),
suspension_state_(),
initialized_threads_(false),
initialized_() {
}
ProcessReaderWin::~ProcessReaderWin() {
}
bool ProcessReaderWin::Initialize(HANDLE process,
ProcessSuspensionState suspension_state) {
INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
process_ = process;
suspension_state_ = suspension_state;
if (!process_info_.Initialize(process))
return false;
if (!process_memory_.Initialize(process))
return false;
INITIALIZATION_STATE_SET_VALID(initialized_);
return true;
}
bool ProcessReaderWin::StartTime(timeval* start_time) const {
FILETIME creation, exit, kernel, user;
if (!GetProcessTimes(process_, &creation, &exit, &kernel, &user)) {
PLOG(ERROR) << "GetProcessTimes";
return false;
}
*start_time = FiletimeToTimevalEpoch(creation);
return true;
}
bool ProcessReaderWin::CPUTimes(timeval* user_time,
timeval* system_time) const {
FILETIME creation, exit, kernel, user;
if (!GetProcessTimes(process_, &creation, &exit, &kernel, &user)) {
PLOG(ERROR) << "GetProcessTimes";
return false;
}
*user_time = FiletimeToTimevalInterval(user);
*system_time = FiletimeToTimevalInterval(kernel);
return true;
}
const std::vector<ProcessReaderWin::Thread>& ProcessReaderWin::Threads() {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
if (initialized_threads_)
return threads_;
initialized_threads_ = true;
#if defined(ARCH_CPU_64_BITS)
ReadThreadData<process_types::internal::Traits64>(process_info_.IsWow64());
#else
ReadThreadData<process_types::internal::Traits32>(false);
#endif
return threads_;
}
const std::vector<ProcessInfo::Module>& ProcessReaderWin::Modules() {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
if (!process_info_.Modules(&modules_)) {
LOG(ERROR) << "couldn't retrieve modules";
}
return modules_;
}
const ProcessInfo& ProcessReaderWin::GetProcessInfo() const {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
return process_info_;
}
void ProcessReaderWin::DecrementThreadSuspendCounts(uint64_t except_thread_id) {
Threads();
for (auto& thread : threads_) {
if (thread.id != except_thread_id) {
DCHECK_GT(thread.suspend_count, 0u);
--thread.suspend_count;
}
}
}
template <class Traits>
void ProcessReaderWin::ReadThreadData(bool is_64_reading_32) {
DCHECK(threads_.empty());
std::unique_ptr<uint8_t[]> buffer;
process_types::SYSTEM_PROCESS_INFORMATION<Traits>* process_information =
GetProcessInformation<Traits>(process_, &buffer);
if (!process_information)
return;
for (unsigned long i = 0; i < process_information->NumberOfThreads; ++i) {
const process_types::SYSTEM_THREAD_INFORMATION<Traits>& thread_info =
process_information->Threads[i];
ProcessReaderWin::Thread thread;
thread.id = thread_info.ClientId.UniqueThread;
ScopedKernelHANDLE thread_handle(OpenThread(thread_info));
if (!thread_handle.is_valid())
continue;
if (!FillThreadContextAndSuspendCount<Traits>(thread_handle.get(),
&thread,
suspension_state_,
is_64_reading_32)) {
continue;
}
// TODO(scottmg): I believe we could reverse engineer the PriorityClass from
// the Priority, BasePriority, and
// https://msdn.microsoft.com/library/ms685100.aspx. MinidumpThreadWriter
// doesn't handle it yet in any case, so investigate both of those at the
// same time if it's useful.
thread.priority_class = NORMAL_PRIORITY_CLASS;
thread.priority = thread_info.Priority;
process_types::THREAD_BASIC_INFORMATION<Traits> thread_basic_info;
NTSTATUS status = crashpad::NtQueryInformationThread(
thread_handle.get(),
static_cast<THREADINFOCLASS>(ThreadBasicInformation),
&thread_basic_info,
sizeof(thread_basic_info),
nullptr);
if (!NT_SUCCESS(status)) {
NTSTATUS_LOG(ERROR, status) << "NtQueryInformationThread";
continue;
}
// Read the TIB (Thread Information Block) which is the first element of the
// TEB, for its stack fields.
process_types::NT_TIB<Traits> tib;
thread.teb_address = thread_basic_info.TebBaseAddress;
thread.teb_size = sizeof(process_types::TEB<Traits>);
if (process_memory_.Read(thread.teb_address, sizeof(tib), &tib)) {
WinVMAddress base = 0;
WinVMAddress limit = 0;
// If we're reading a WOW64 process, then the TIB we just retrieved is the
// x64 one. The first word of the x64 TIB points at the x86 TIB. See
// https://msdn.microsoft.com/library/dn424783.aspx.
if (is_64_reading_32) {
process_types::NT_TIB<process_types::internal::Traits32> tib32;
thread.teb_address = tib.Wow64Teb;
thread.teb_size =
sizeof(process_types::TEB<process_types::internal::Traits32>);
if (process_memory_.Read(thread.teb_address, sizeof(tib32), &tib32)) {
base = tib32.StackBase;
limit = tib32.StackLimit;
}
} else {
base = tib.StackBase;
limit = tib.StackLimit;
}
// Note, "backwards" because of direction of stack growth.
thread.stack_region_address = limit;
if (limit > base) {
LOG(ERROR) << "invalid stack range: " << base << " - " << limit;
thread.stack_region_size = 0;
} else {
thread.stack_region_size = base - limit;
}
}
threads_.push_back(thread);
}
}
} // namespace crashpad