XServiceManager

中文

What is this

A system service injection framework that allows bypassing SELinux policies in order to add custom services to system services.

Usage Scenarios

• System development can be integrated into aosp as part of the framework
• Xposed development injects services into the framework layer for other applications to call

How to works

After Android 5.0, it is limited by SELinux mandatory policy, so adding services to the system needs to modify the sepolicy policy which is very difficult for inexperienced developers, so there is XServiceManager project. You can easily add services to the framework to make them available to other applications. The XServiceManager hosts the system clipboard service by hijacking it, and custom services are actually managed by the XServiceManager on your behalf rather than actually added to the system ServiceManager, so your service must be added via the XServiceManager interface to add calls.

Supported Versions

Android 5.0+

How to use

Here only the xposed integration method aosp integration method similar please study yourself

1. Clone the XServiceManager project to the project root git clone https://github.com/kaisar945/XServiceManager.git libxservicemanager

2. Open the build.gradle file in the main project and add the implementation project(path: ':libxservicemanager') dependency to the dependencies section

3. Writing custom services

4. In the Xposed initialization class after confirming that the current process is the system_server process add the initialization code and add a custom service

   1. No dependency on system services and Context

      public void handleLoadPackage(final XC_LoadPackage.LoadPackageParam lpparam) {
          if("android".equals(lpparam.packageName)){
              XServiceManager.initForSystemServer();
              XServiceManager.addService("simple", new SimpleService());
          }
      }

   2. Dependency on system services and Context

      public void handleLoadPackage(final XC_LoadPackage.LoadPackageParam lpparam) {
          if("android".equals(lpparam.packageName)){
              XServiceManager.initForSystemServer();
              XServiceManager.registerService("simple2", new XServiceManager.ServiceFetcher<Binder>()
              {
                  @Override
                  public Binder createService(Context ctx)
                  {
                      return new SimpleService2(ctx);
                  }
              });    
          }
      }

5. Use custom services in other applications

   Tip:The service object obtained in case of injection failure is null, so please always check the service object before using the service.

   • Use getService or getServiceInterface of XServiceManager class to get the service object

   IBinder binder = XServiceManager.getService("simple");
   if(binder != null){
   	ISimpleService service = ISimpleService.Stub.asInterface(binder);
   	service.doSomething();
   }

   // Use the getServiceInterface function to get a service. Make sure the service interface is not obfuscated. -keep class com.your.ISimpleService$* {*;}
   ISimpleService service = XServiceManager.getServiceInterface("simple");
   if(service != null){
       service.doSomething();
   }

Risk

Because the custom service runs in the system_server process and therefore has the highest system privileges, please ensure that the security and stability of the service is taken into account at the beginning of the design otherwise it may cause the device to run unstable

FAQ

• Unable to call custom services

  Filter the XServiceManager logs to check if the following logs are available

  XServiceManager inject success
  

  If you do not find a successful injection hint there should be some other exception hints please check if it is caused by your service if not congratulations you have found a bug please submit an issue to me

• Storing data files in custom services

  Custom services belong to the system user group by default and are restricted by SELinux from storing data in paths other than /data/system, so you can choose to create a proprietary directory in that directory for data storage.

• TransactionTooLargeException occurs when calling the service

  This error is caused by the IPC data buffer limit which is about 1Mb Please avoid large data exchange