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// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "mojo/core/platform_handle_in_transit.h"
#include <utility>
#include "base/debug/alias.h"
#include "base/logging.h"
#include "base/process/process_handle.h"
#include "build/build_config.h"
#if BUILDFLAG(IS_WIN)
#include <windows.h>
#include <ntstatus.h>
#include "base/win/nt_status.h"
#include "base/win/scoped_handle.h"
#include "base/win/win_util.h"
#include "mojo/public/cpp/platform/platform_handle_security_util_win.h"
#endif
namespace mojo {
namespace core {
namespace {
#if BUILDFLAG(IS_WIN)
HANDLE TransferHandle(HANDLE handle,
base::ProcessHandle from_process,
base::ProcessHandle to_process,
PlatformHandleInTransit::TransferTargetTrustLevel trust) {
if (trust == PlatformHandleInTransit::kUntrustedTarget) {
MaybeCheckIfHandleIsUnsafe(handle);
}
// Duplicating INVALID_HANDLE_VALUE passes a process handle. If you intend to
// do this, you must open a valid process handle, not pass the result of
// GetCurrentProcess() or GetCurrentThread(). e.g. https://crbug.com/243339.
CHECK(!base::win::IsPseudoHandle(handle));
HANDLE out_handle;
BOOL result =
::DuplicateHandle(from_process, handle, to_process, &out_handle, 0, FALSE,
DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE);
if (result) {
return out_handle;
}
const DWORD error = ::GetLastError();
// ERROR_ACCESS_DENIED may indicate that the remote process (which could be
// either the source or destination process here) is already terminated or has
// begun termination and therefore no longer has a handle table. We don't want
// these cases to crash because we know they happen in practice and are
// largely unavoidable.
if (error == ERROR_ACCESS_DENIED &&
base::win::GetLastNtStatus() == STATUS_PROCESS_IS_TERMINATING) {
DVLOG(1) << "DuplicateHandle from " << from_process << " to " << to_process
<< " for handle " << handle
<< " failed due to process termination";
return INVALID_HANDLE_VALUE;
}
base::debug::Alias(&handle);
base::debug::Alias(&from_process);
base::debug::Alias(&to_process);
base::debug::Alias(&error);
PLOG(FATAL) << "DuplicateHandle failed from " << from_process << " to "
<< to_process << " for handle " << handle;
return INVALID_HANDLE_VALUE;
}
void CloseHandleInProcess(HANDLE handle, const base::Process& process) {
DCHECK_NE(handle, INVALID_HANDLE_VALUE);
DCHECK(process.IsValid());
// The handle lives in |process|, so we close it there using a special
// incantation of |DuplicateHandle()|.
//
// See https://msdn.microsoft.com/en-us/library/windows/desktop/ms724251 for
// this usage of |DuplicateHandle()|, particularly where it says "to close a
// handle from the source process...". Note that although the documentation
// says that the target *handle* address must be NULL, it seems that the
// target process handle being NULL is what really matters here.
BOOL result = ::DuplicateHandle(process.Handle(), handle, nullptr, &handle, 0,
FALSE, DUPLICATE_CLOSE_SOURCE);
if (!result) {
DPLOG(ERROR) << "DuplicateHandle failed";
}
}
#endif
} // namespace
PlatformHandleInTransit::PlatformHandleInTransit() = default;
PlatformHandleInTransit::PlatformHandleInTransit(PlatformHandle handle)
: handle_(std::move(handle)) {}
PlatformHandleInTransit::PlatformHandleInTransit(
PlatformHandleInTransit&& other) {
*this = std::move(other);
}
PlatformHandleInTransit::~PlatformHandleInTransit() {
#if BUILDFLAG(IS_WIN)
if (!owning_process_.IsValid()) {
DCHECK_EQ(remote_handle_, INVALID_HANDLE_VALUE);
return;
}
CloseHandleInProcess(remote_handle_, owning_process_);
#endif
}
PlatformHandleInTransit& PlatformHandleInTransit::operator=(
PlatformHandleInTransit&& other) {
#if BUILDFLAG(IS_WIN)
if (owning_process_.IsValid()) {
DCHECK_NE(remote_handle_, INVALID_HANDLE_VALUE);
CloseHandleInProcess(remote_handle_, owning_process_);
}
remote_handle_ = INVALID_HANDLE_VALUE;
std::swap(remote_handle_, other.remote_handle_);
#endif
handle_ = std::move(other.handle_);
owning_process_ = std::move(other.owning_process_);
return *this;
}
PlatformHandle PlatformHandleInTransit::TakeHandle() {
DCHECK(!owning_process_.IsValid());
return std::move(handle_);
}
void PlatformHandleInTransit::CompleteTransit() {
#if BUILDFLAG(IS_WIN)
remote_handle_ = INVALID_HANDLE_VALUE;
#endif
handle_.release();
owning_process_ = base::Process();
}
bool PlatformHandleInTransit::TransferToProcess(
base::Process target_process,
TransferTargetTrustLevel trust) {
DCHECK(target_process.IsValid());
DCHECK(!owning_process_.IsValid());
DCHECK(handle_.is_valid());
#if BUILDFLAG(IS_WIN)
remote_handle_ =
TransferHandle(handle_.ReleaseHandle(), base::GetCurrentProcessHandle(),
target_process.Handle(), trust);
if (remote_handle_ == INVALID_HANDLE_VALUE)
return false;
#endif
owning_process_ = std::move(target_process);
return true;
}
#if BUILDFLAG(IS_WIN)
// static
bool PlatformHandleInTransit::IsPseudoHandle(HANDLE handle) {
return base::win::IsPseudoHandle(handle);
}
// static
PlatformHandle PlatformHandleInTransit::TakeIncomingRemoteHandle(
HANDLE handle,
base::ProcessHandle owning_process) {
return PlatformHandle(base::win::ScopedHandle(
TransferHandle(handle, owning_process, base::GetCurrentProcessHandle(),
kTrustedTarget)));
}
#endif
} // namespace core
} // namespace mojo
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