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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/child_process_task_port_provider_mac.h"
#include <map>
#include "base/apple/foundation_util.h"
#include "base/apple/mach_logging.h"
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/no_destructor.h"
#include "base/strings/stringprintf.h"
#include "build/build_config.h"
#include "content/common/child_process.mojom.h"
#include "mojo/public/cpp/system/platform_handle.h"
#if BUILDFLAG(IS_MAC)
#include "content/common/mac/system_policy.h"
#endif
namespace content {
ChildProcessTaskPortProvider* ChildProcessTaskPortProvider::GetInstance() {
static base::NoDestructor<ChildProcessTaskPortProvider> provider;
return provider.get();
}
void ChildProcessTaskPortProvider::OnChildProcessLaunched(
base::ProcessHandle process_handle,
mojom::ChildProcess* child_process) {
if (!ShouldRequestTaskPorts())
return;
child_process->GetTaskPort(
base::BindOnce(&ChildProcessTaskPortProvider::OnTaskPortReceived,
base::Unretained(this), process_handle));
}
mach_port_t ChildProcessTaskPortProvider::TaskForHandle(
base::ProcessHandle process_handle) const {
base::AutoLock lock(lock_);
auto it = handle_to_task_port_.find(process_handle);
if (it == handle_to_task_port_.end()) {
return MACH_PORT_NULL;
}
return it->second.get();
}
ChildProcessTaskPortProvider::ChildProcessTaskPortProvider() {
if (!ShouldRequestTaskPorts()) {
LOG(WARNING) << "AppleMobileFileIntegrity is disabled. The browser will "
"not collect child process task ports.";
return;
}
CHECK(base::apple::CreateMachPort(¬ification_port_, nullptr));
const std::string dispatch_name = base::StringPrintf(
"%s.ChildProcessTaskPortProvider.%p", base::apple::BaseBundleID(), this);
notification_source_ = std::make_unique<base::apple::DispatchSource>(
dispatch_name.c_str(), notification_port_.get(), ^{
OnTaskPortDied();
});
notification_source_->Resume();
}
ChildProcessTaskPortProvider::~ChildProcessTaskPortProvider() {}
bool ChildProcessTaskPortProvider::ShouldRequestTaskPorts() const {
#if BUILDFLAG(IS_MAC)
static const bool should_request_task_ports = []() -> bool {
auto policy = GetMachTaskPortPolicy();
return policy
.transform([](auto policy) { return !policy.AmfiIsAllowEverything(); })
.value_or(true);
}();
return should_request_task_ports;
#else
return true;
#endif
}
void ChildProcessTaskPortProvider::OnTaskPortReceived(
base::ProcessHandle process_handle,
mojo::PlatformHandle task_port) {
DCHECK(ShouldRequestTaskPorts());
if (!task_port.is_mach_send()) {
DLOG(ERROR) << "Invalid handle received as task port for pid "
<< base::GetProcId(process_handle);
return;
}
base::apple::ScopedMachSendRight port = task_port.TakeMachSendRight();
// Request a notification from the kernel for when the port becomes a dead
// name, indicating that the process has died.
base::apple::ScopedMachSendRight previous;
kern_return_t kr = mach_port_request_notification(
mach_task_self(), port.get(), MACH_NOTIFY_DEAD_NAME, 0,
notification_port_.get(), MACH_MSG_TYPE_MAKE_SEND_ONCE,
base::apple::ScopedMachSendRight::Receiver(previous).get());
if (kr != KERN_SUCCESS) {
// If the argument was invalid, the process is likely already dead.
MACH_DVLOG(1, kr) << "mach_port_request_notification";
return;
}
DVLOG(1) << "Received task port for PID=" << base::GetProcId(process_handle)
<< ", port name=" << port.get();
{
base::AutoLock lock(lock_);
auto it = handle_to_task_port_.find(process_handle);
if (it == handle_to_task_port_.end()) {
handle_to_task_port_.emplace(process_handle, std::move(port));
} else {
// If a task port already exists for the PID, then reset it if the port
// is of a different name. The port name may be the same when running in
// single-process mode, tests, or if the PID is reused and this races the
// DEAD_NAME notification. Self-reseting is not allowed on ScopedGeneric,
// so test for that first.
if (it->second.get() != port.get())
it->second = std::move(port);
}
}
NotifyObservers(process_handle);
}
void ChildProcessTaskPortProvider::OnTaskPortDied() {
DCHECK(ShouldRequestTaskPorts());
mach_dead_name_notification_t notification{};
kern_return_t kr =
mach_msg(¬ification.not_header, MACH_RCV_MSG | MACH_RCV_TIMEOUT, 0,
sizeof(notification), notification_port_.get(), /*timeout=*/0,
MACH_PORT_NULL);
if (kr != KERN_SUCCESS) {
MACH_LOG(ERROR, kr) << "mach_msg";
return;
}
// A NOTIFY_SEND_ONCE might be delivered from the send-once right allocated
// via mach_port_request_notification().
if (notification.not_header.msgh_id != MACH_NOTIFY_DEAD_NAME)
return;
// Release the DEAD_NAME right.
base::apple::ScopedMachSendRight dead_port(notification.not_port);
base::AutoLock lock(lock_);
std::erase_if(handle_to_task_port_, [&dead_port](const auto& pair) {
if (pair.second.get() == dead_port.get()) {
DVLOG(1) << "Task died, PID=" << base::GetProcId(pair.first)
<< ", task port name=" << dead_port.get();
return true;
}
return false;
});
}
} // namespace content
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