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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "mojo/core/broker_host.h"
#include <algorithm>
#include <array>
#include <string_view>
#include <utility>
#include "base/logging.h"
#include "base/memory/platform_shared_memory_region.h"
#include "base/memory/ref_counted.h"
#include "base/task/single_thread_task_runner.h"
#include "build/build_config.h"
#include "mojo/buildflags.h"
#include "mojo/core/broker_messages.h"
#include "mojo/core/ipcz_driver/envelope.h"
#include "mojo/core/platform_handle_utils.h"
#if BUILDFLAG(IS_WIN)
#include <windows.h>
#endif
namespace mojo {
namespace core {
BrokerHost::BrokerHost(base::Process client_process,
ConnectionParams connection_params,
const ProcessErrorCallback& process_error_callback)
: process_error_callback_(process_error_callback)
#if BUILDFLAG(IS_WIN)
,
client_process_(std::move(client_process))
#endif
{
base::CurrentThread::Get()->AddDestructionObserver(this);
CHECK(connection_params.endpoint().is_valid());
channel_ = Channel::Create(this, std::move(connection_params),
#if BUILDFLAG(IS_WIN)
client_process_
#else
client_process
#endif
.IsValid()
? Channel::HandlePolicy::kAcceptHandles
: Channel::HandlePolicy::kRejectHandles,
base::SingleThreadTaskRunner::GetCurrentDefault());
channel_->Start();
}
BrokerHost::~BrokerHost() {
// We're always destroyed on the creation thread, which is the IO thread.
base::CurrentThread::Get()->RemoveDestructionObserver(this);
if (channel_)
channel_->ShutDown();
}
bool BrokerHost::PrepareHandlesForClient(
std::vector<PlatformHandleInTransit>* handles) {
#if BUILDFLAG(IS_WIN)
if (!client_process_.IsValid())
return false;
bool handles_ok = true;
for (auto& handle : *handles) {
if (!handle.TransferToProcess(client_process_.Duplicate()))
handles_ok = false;
}
return handles_ok;
#else
return true;
#endif
}
bool BrokerHost::SendChannel(PlatformHandle handle) {
CHECK(handle.is_valid());
CHECK(channel_);
#if BUILDFLAG(IS_WIN)
InitData* data;
Channel::MessagePtr message =
CreateBrokerMessage(BrokerMessageType::INIT, 1, 0, &data);
data->pipe_name_length = 0;
#else
Channel::MessagePtr message =
CreateBrokerMessage(BrokerMessageType::INIT, 1, nullptr);
#endif
std::vector<PlatformHandleInTransit> handles(1);
handles[0] = PlatformHandleInTransit(std::move(handle));
// This may legitimately fail on Windows if the client process is in another
// session, e.g., is an elevated process.
if (!PrepareHandlesForClient(&handles))
return false;
message->SetHandles(std::move(handles));
channel_->Write(std::move(message));
return true;
}
#if BUILDFLAG(IS_WIN)
void BrokerHost::SendNamedChannel(std::wstring_view pipe_name) {
InitData* data;
wchar_t* name_data;
Channel::MessagePtr message = CreateBrokerMessage(
BrokerMessageType::INIT, 0, sizeof(*name_data) * pipe_name.length(),
&data, reinterpret_cast<void**>(&name_data));
data->pipe_name_length = static_cast<uint32_t>(pipe_name.length());
std::ranges::copy(pipe_name, name_data);
channel_->Write(std::move(message));
}
#endif // BUILDFLAG(IS_WIN)
void BrokerHost::OnBufferRequest(uint32_t num_bytes) {
base::subtle::PlatformSharedMemoryRegion region =
base::subtle::PlatformSharedMemoryRegion::CreateWritable(num_bytes);
std::vector<PlatformHandleInTransit> handles;
handles.reserve(2);
if (region.IsValid()) {
std::array<PlatformHandle, 2> h;
ExtractPlatformHandlesFromSharedMemoryRegionHandle(
region.PassPlatformHandle(), &h[0], &h[1]);
handles.emplace_back(std::move(h[0]));
#if !BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_ANDROID) || \
BUILDFLAG(MOJO_USE_APPLE_CHANNEL)
// Non-POSIX systems, as well as Android and Mac, only use a single handle
// to represent a writable region.
DCHECK(!h[1].is_valid());
#else
DCHECK(h[1].is_valid());
handles.emplace_back(std::move(h[1]));
#endif
}
BufferResponseData* response;
Channel::MessagePtr message = CreateBrokerMessage(
BrokerMessageType::BUFFER_RESPONSE, handles.size(), 0, &response);
if (handles.empty()) {
response->guid_high = 0;
response->guid_low = 0;
} else {
const base::UnguessableToken& guid = region.GetGUID();
response->guid_high = guid.GetHighForSerialization();
response->guid_low = guid.GetLowForSerialization();
PrepareHandlesForClient(&handles);
message->SetHandles(std::move(handles));
}
channel_->Write(std::move(message));
}
void BrokerHost::OnChannelMessage(
const void* payload,
size_t payload_size,
std::vector<PlatformHandle> handles,
scoped_refptr<ipcz_driver::Envelope> envelope) {
if (payload_size < sizeof(BrokerMessageHeader))
return;
const BrokerMessageHeader* header =
static_cast<const BrokerMessageHeader*>(payload);
switch (header->type) {
case BrokerMessageType::BUFFER_REQUEST:
if (payload_size ==
sizeof(BrokerMessageHeader) + sizeof(BufferRequestData)) {
const BufferRequestData* request =
reinterpret_cast<const BufferRequestData*>(header + 1);
OnBufferRequest(request->size);
}
break;
default:
DLOG(ERROR) << "Unexpected broker message type: " << header->type;
break;
}
}
void BrokerHost::OnChannelError(Channel::Error error) {
if (process_error_callback_ &&
error == Channel::Error::kReceivedMalformedData) {
process_error_callback_.Run("Broker host received malformed message");
}
delete this;
}
void BrokerHost::WillDestroyCurrentMessageLoop() {
delete this;
}
} // namespace core
} // namespace mojo
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