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/*
* Copyright (C) 2005 The Android Open Source Project
*
* 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.
*/
#define LOG_TAG "ServiceManager"
#include <binder/IServiceManager.h>
#include <inttypes.h>
#include <unistd.h>
#include <android/os/BnServiceCallback.h>
#include <android/os/IServiceManager.h>
#include <binder/IPCThreadState.h>
#include <binder/Parcel.h>
#include <utils/Log.h>
#include <utils/String8.h>
#include <utils/SystemClock.h>
#ifndef __ANDROID_VNDK__
#include <binder/IPermissionController.h>
#endif
#ifdef __ANDROID__
#include <cutils/properties.h>
#endif
#include "Static.h"
namespace android {
using AidlServiceManager = android::os::IServiceManager;
using android::binder::Status;
// libbinder's IServiceManager.h can't rely on the values generated by AIDL
// because many places use its headers via include_dirs (meaning, without
// declaring the dependency in the build system). So, for now, we can just check
// the values here.
static_assert(AidlServiceManager::DUMP_FLAG_PRIORITY_CRITICAL == IServiceManager::DUMP_FLAG_PRIORITY_CRITICAL);
static_assert(AidlServiceManager::DUMP_FLAG_PRIORITY_HIGH == IServiceManager::DUMP_FLAG_PRIORITY_HIGH);
static_assert(AidlServiceManager::DUMP_FLAG_PRIORITY_NORMAL == IServiceManager::DUMP_FLAG_PRIORITY_NORMAL);
static_assert(AidlServiceManager::DUMP_FLAG_PRIORITY_DEFAULT == IServiceManager::DUMP_FLAG_PRIORITY_DEFAULT);
static_assert(AidlServiceManager::DUMP_FLAG_PRIORITY_ALL == IServiceManager::DUMP_FLAG_PRIORITY_ALL);
static_assert(AidlServiceManager::DUMP_FLAG_PROTO == IServiceManager::DUMP_FLAG_PROTO);
const String16& IServiceManager::getInterfaceDescriptor() const {
return AidlServiceManager::descriptor;
}
IServiceManager::IServiceManager() {}
IServiceManager::~IServiceManager() {}
// From the old libbinder IServiceManager interface to IServiceManager.
class ServiceManagerShim : public IServiceManager
{
public:
explicit ServiceManagerShim (const sp<AidlServiceManager>& impl);
sp<IBinder> getService(const String16& name) const override;
sp<IBinder> checkService(const String16& name) const override;
status_t addService(const String16& name, const sp<IBinder>& service,
bool allowIsolated, int dumpsysPriority) override;
Vector<String16> listServices(int dumpsysPriority) override;
sp<IBinder> waitForService(const String16& name16) override;
bool isDeclared(const String16& name) override;
// for legacy ABI
const String16& getInterfaceDescriptor() const override {
return mTheRealServiceManager->getInterfaceDescriptor();
}
IBinder* onAsBinder() override {
return IInterface::asBinder(mTheRealServiceManager).get();
}
private:
sp<AidlServiceManager> mTheRealServiceManager;
};
[[clang::no_destroy]] static std::once_flag gSmOnce;
[[clang::no_destroy]] static sp<IServiceManager> gDefaultServiceManager;
sp<IServiceManager> defaultServiceManager()
{
std::call_once(gSmOnce, []() {
sp<AidlServiceManager> sm = nullptr;
while (sm == nullptr) {
sm = interface_cast<AidlServiceManager>(ProcessState::self()->getContextObject(nullptr));
if (sm == nullptr) {
ALOGE("Waiting 1s on context object on %s.", ProcessState::self()->getDriverName().c_str());
sleep(1);
}
}
gDefaultServiceManager = new ServiceManagerShim(sm);
});
return gDefaultServiceManager;
}
void setDefaultServiceManager(const sp<IServiceManager>& sm) {
bool called = false;
std::call_once(gSmOnce, [&]() {
gDefaultServiceManager = sm;
called = true;
});
if (!called) {
LOG_ALWAYS_FATAL("setDefaultServiceManager() called after defaultServiceManager().");
}
}
#if !defined(__ANDROID_VNDK__) && defined(__ANDROID__)
// IPermissionController is not accessible to vendors
bool checkCallingPermission(const String16& permission)
{
return checkCallingPermission(permission, nullptr, nullptr);
}
static String16 _permission("permission");
bool checkCallingPermission(const String16& permission, int32_t* outPid, int32_t* outUid)
{
IPCThreadState* ipcState = IPCThreadState::self();
pid_t pid = ipcState->getCallingPid();
uid_t uid = ipcState->getCallingUid();
if (outPid) *outPid = pid;
if (outUid) *outUid = uid;
return checkPermission(permission, pid, uid);
}
bool checkPermission(const String16& permission, pid_t pid, uid_t uid)
{
static Mutex gPermissionControllerLock;
static sp<IPermissionController> gPermissionController;
sp<IPermissionController> pc;
gPermissionControllerLock.lock();
pc = gPermissionController;
gPermissionControllerLock.unlock();
int64_t startTime = 0;
while (true) {
if (pc != nullptr) {
bool res = pc->checkPermission(permission, pid, uid);
if (res) {
if (startTime != 0) {
ALOGI("Check passed after %d seconds for %s from uid=%d pid=%d",
(int)((uptimeMillis()-startTime)/1000),
String8(permission).string(), uid, pid);
}
return res;
}
// Is this a permission failure, or did the controller go away?
if (IInterface::asBinder(pc)->isBinderAlive()) {
ALOGW("Permission failure: %s from uid=%d pid=%d",
String8(permission).string(), uid, pid);
return false;
}
// Object is dead!
gPermissionControllerLock.lock();
if (gPermissionController == pc) {
gPermissionController = nullptr;
}
gPermissionControllerLock.unlock();
}
// Need to retrieve the permission controller.
sp<IBinder> binder = defaultServiceManager()->checkService(_permission);
if (binder == nullptr) {
// Wait for the permission controller to come back...
if (startTime == 0) {
startTime = uptimeMillis();
ALOGI("Waiting to check permission %s from uid=%d pid=%d",
String8(permission).string(), uid, pid);
}
sleep(1);
} else {
pc = interface_cast<IPermissionController>(binder);
// Install the new permission controller, and try again.
gPermissionControllerLock.lock();
gPermissionController = pc;
gPermissionControllerLock.unlock();
}
}
}
#endif //__ANDROID_VNDK__
// ----------------------------------------------------------------------
ServiceManagerShim::ServiceManagerShim(const sp<AidlServiceManager>& impl)
: mTheRealServiceManager(impl)
{}
// This implementation could be simplified and made more efficient by delegating
// to waitForService. However, this changes the threading structure in some
// cases and could potentially break prebuilts. Once we have higher logistical
// complexity, this could be attempted.
sp<IBinder> ServiceManagerShim::getService(const String16& name) const
{
static bool gSystemBootCompleted = false;
sp<IBinder> svc = checkService(name);
if (svc != nullptr) return svc;
const bool isVendorService =
strcmp(ProcessState::self()->getDriverName().c_str(), "/dev/vndbinder") == 0;
const long timeout = 5000;
int64_t startTime = uptimeMillis();
// Vendor code can't access system properties
if (!gSystemBootCompleted && !isVendorService) {
#ifdef __ANDROID__
char bootCompleted[PROPERTY_VALUE_MAX];
property_get("sys.boot_completed", bootCompleted, "0");
gSystemBootCompleted = strcmp(bootCompleted, "1") == 0 ? true : false;
#else
gSystemBootCompleted = true;
#endif
}
// retry interval in millisecond; note that vendor services stay at 100ms
const long sleepTime = gSystemBootCompleted ? 1000 : 100;
ALOGI("Waiting for service '%s' on '%s'...", String8(name).string(),
ProcessState::self()->getDriverName().c_str());
int n = 0;
while (uptimeMillis() - startTime < timeout) {
n++;
usleep(1000*sleepTime);
sp<IBinder> svc = checkService(name);
if (svc != nullptr) {
ALOGI("Waiting for service '%s' on '%s' successful after waiting %" PRIi64 "ms",
String8(name).string(), ProcessState::self()->getDriverName().c_str(),
uptimeMillis() - startTime);
return svc;
}
}
ALOGW("Service %s didn't start. Returning NULL", String8(name).string());
return nullptr;
}
sp<IBinder> ServiceManagerShim::checkService(const String16& name) const
{
sp<IBinder> ret;
if (!mTheRealServiceManager->checkService(String8(name).c_str(), &ret).isOk()) {
return nullptr;
}
return ret;
}
status_t ServiceManagerShim::addService(const String16& name, const sp<IBinder>& service,
bool allowIsolated, int dumpsysPriority)
{
Status status = mTheRealServiceManager->addService(
String8(name).c_str(), service, allowIsolated, dumpsysPriority);
return status.exceptionCode();
}
Vector<String16> ServiceManagerShim::listServices(int dumpsysPriority)
{
std::vector<std::string> ret;
if (!mTheRealServiceManager->listServices(dumpsysPriority, &ret).isOk()) {
return {};
}
Vector<String16> res;
res.setCapacity(ret.size());
for (const std::string& name : ret) {
res.push(String16(name.c_str()));
}
return res;
}
sp<IBinder> ServiceManagerShim::waitForService(const String16& name16)
{
class Waiter : public android::os::BnServiceCallback {
Status onRegistration(const std::string& /*name*/,
const sp<IBinder>& binder) override {
std::unique_lock<std::mutex> lock(mMutex);
mBinder = binder;
lock.unlock();
// Flushing here helps ensure the service's ref count remains accurate
IPCThreadState::self()->flushCommands();
mCv.notify_one();
return Status::ok();
}
public:
sp<IBinder> mBinder;
std::mutex mMutex;
std::condition_variable mCv;
};
// Simple RAII object to ensure a function call immediately before going out of scope
class Defer {
public:
Defer(std::function<void()>&& f) : mF(std::move(f)) {}
~Defer() { mF(); }
private:
std::function<void()> mF;
};
const std::string name = String8(name16).c_str();
sp<IBinder> out;
if (!mTheRealServiceManager->getService(name, &out).isOk()) {
return nullptr;
}
if (out != nullptr) return out;
sp<Waiter> waiter = new Waiter;
if (!mTheRealServiceManager->registerForNotifications(
name, waiter).isOk()) {
return nullptr;
}
Defer unregister ([&] {
mTheRealServiceManager->unregisterForNotifications(name, waiter);
});
while(true) {
{
// It would be really nice if we could read binder commands on this
// thread instead of needing a threadpool to be started, but for
// instance, if we call getAndExecuteCommand, it might be the case
// that another thread serves the callback, and we never get a
// command, so we hang indefinitely.
std::unique_lock<std::mutex> lock(waiter->mMutex);
using std::literals::chrono_literals::operator""s;
waiter->mCv.wait_for(lock, 1s, [&] {
return waiter->mBinder != nullptr;
});
if (waiter->mBinder != nullptr) return waiter->mBinder;
}
ALOGW("Waited one second for %s (is service started? are binder threads started and available?)", name.c_str());
// Handle race condition for lazy services. Here is what can happen:
// - the service dies (not processed by init yet).
// - sm processes death notification.
// - sm gets getService and calls init to start service.
// - init gets the start signal, but the service already appears
// started, so it does nothing.
// - init gets death signal, but doesn't know it needs to restart
// the service
// - we need to request service again to get it to start
if (!mTheRealServiceManager->getService(name, &out).isOk()) {
return nullptr;
}
if (out != nullptr) return out;
}
}
bool ServiceManagerShim::isDeclared(const String16& name) {
bool declared;
if (!mTheRealServiceManager->isDeclared(String8(name).c_str(), &declared).isOk()) {
return false;
}
return declared;
}
} // namespace android