带android:sharedUserId=“android.uid.system” 发送广播时,会出现 Sending non-protected broadcast 异常提醒;
原因:
Ams在发送广播时,对于systemApp(系统应用),会要求发送广播必须是声明在frameworks\base\core\res\AndroidManifest.xml里面的protected-broadcast。这是为了提醒 系统应用开发者要将 broadcast 添加到protected-broadcast,因为非 protexted-broadcast 广播是可以被三方应用发送的。定义为 proected-broadcast 可以避免三方垃圾应用也发送这些广播来捣蛋。
查找问题
首先去搜索问题出现的位置 ,去AndroidXRef网站搜索下
定位到frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
类中,在checkBroadcastFromSystem
中抛出该异常。
checkBroadcastFromSytem是用于检测系统应用发出的广播是否安全,如果发出的广播不安全,就会抛出no-protected broadcast
异常,提醒系统应用开发者。
为什么要有这个机制?
这是为了提醒 系统应用开发者去将 broadcast添加为protected-broadcast,因为非 protected-broadcast 广播是可以被三方应用发送的。 而定义为 proected-broadcast 就能防止恶意的三方应用模仿系统应用去发出该广播。
private void checkBroadcastFromSystem(Intent intent, ProcessRecord callerApp, String callerPackage, int callingUid, boolean isProtectedBroadcast, List receivers) { if ((intent.getFlags() & Intent.FLAG_RECEIVER_FROM_SHELL) != 0) { // Don't yell about broadcasts sent via shell return; } final String action = intent.getAction(); if (isProtectedBroadcast || Intent.ACTION_CLOSE_SYSTEM_DIALOGS.equals(action) || Intent.ACTION_DISMISS_KEYBOARD_SHORTCUTS.equals(action) || Intent.ACTION_MEDIA_BUTTON.equals(action) || Intent.ACTION_MEDIA_SCANNER_SCAN_FILE.equals(action) || Intent.ACTION_SHOW_KEYBOARD_SHORTCUTS.equals(action) || Intent.ACTION_MASTER_CLEAR.equals(action) || Intent.ACTION_FACTORY_RESET.equals(action) || AppWidgetManager.ACTION_APPWIDGET_CONFIGURE.equals(action) || AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action) || LocationManager.HIGH_POWER_REQUEST_CHANGE_ACTION.equals(action) || TelephonyIntents.ACTION_REQUEST_OMADM_CONFIGURATION_UPDATE.equals(action) || SuggestionSpan.ACTION_SUGGESTION_PICKED.equals(action) || AudioEffect.ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION.equals(action) || AudioEffect.ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION.equals(action)) { // Broadcast is either protected, or it's a public action that // we've relaxed, so it's fine for system internals to send. return; } // This broadcast may be a problem... but there are often system components that // want to send an internal broadcast to themselves, which is annoying to have to // explicitly list each action as a protected broadcast, so we will check for that // one safe case and allow it: an explicit broadcast, only being received by something // that has protected itself. if (intent.getPackage() != null || intent.getComponent() != null) { if (receivers == null || receivers.size() == 0) { // Intent is explicit and there's no receivers. // This happens, e.g. , when a system component sends a broadcast to // its own runtime receiver, and there's no manifest receivers for it, // because this method is called twice for each broadcast, // for runtime receivers and manifest receivers and the later check would find // no receivers. return; } boolean allProtected = true; for (int i = receivers.size()-1; i >= 0; i--) { Object target = receivers.get(i); if (target instanceof ResolveInfo) { ResolveInfo ri = (ResolveInfo)target; if (ri.activityInfo.exported && ri.activityInfo.permission == null) { allProtected = false; break; } } else { BroadcastFilter bf = (BroadcastFilter)target; if (bf.requiredPermission == null) { allProtected = false; break; } } } if (allProtected) { // All safe! return; } } // The vast majority of broadcasts sent from system internals // should be protected to avoid security holes, so yell loudly // to ensure we examine these cases. if (callerApp != null) { Log.wtf(TAG, "Sending non-protected broadcast " + action + " from system " + callerApp.toShortString() + " pkg " + callerPackage, new Throwable()); } else { Log.wtf(TAG, "Sending non-protected broadcast " + action + " from system uid " + UserHandle.formatUid(callingUid) + " pkg " + callerPackage, new Throwable()); } }
如上代码, 对于广播,checkBroadcastFromSystem方法有三种检测。
- 如果Action 是Shell 发出的,则直接返回,不发出警告
- 如果Action 是protected-broadcast广播或一些指定的Action,不发出警告
- 如果Action 是指定了包名或者Compononent信息,只有特定应用能接收,则当所有receiver 均根据receiverPermisson 对权限进行了顾虑,则不发出警告
如果系统应用不满足以上三种情况,则发送公共广播时会被警告
如何解决 non-protected broadcast警告
从系统源码层面
1.在checkBroadcastFromSystem 处修改
if (isProtectedBroadcast || Intent.ACTION_CLOSE_SYSTEM_DIALOGS.equals(action) || Intent.ACTION_DISMISS_KEYBOARD_SHORTCUTS.equals(action) || Intent.ACTION_MEDIA_BUTTON.equals(action) || Intent.ACTION_MEDIA_SCANNER_SCAN_FILE.equals(action) || Intent.ACTION_SHOW_KEYBOARD_SHORTCUTS.equals(action) || Intent.ACTION_MASTER_CLEAR.equals(action) || Intent.ACTION_FACTORY_RESET.equals(action) || AppWidgetManager.ACTION_APPWIDGET_CONFIGURE.equals(action) || AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action) || LocationManager.HIGH_POWER_REQUEST_CHANGE_ACTION.equals(action) || TelephonyIntents.ACTION_REQUEST_OMADM_CONFIGURATION_UPDATE.equals(action) || SuggestionSpan.ACTION_SUGGESTION_PICKED.equals(action) || AudioEffect.ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION.equals(action) || AudioEffect.ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION.equals(action)) { // Broadcast is either protected, or it's a public action that // we've relaxed, so it's fine for system internals to send. return; } 复制代码
2在/frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java#isProtectedBroadcast方法处修改
3.在/frameworks/base/core/res/AndroidManifest.xml 处增加 protected-broadcast
标签
在应用层面修改
- 在系统应用的
AndroidManifest.xml
处增加protected-broadcast
标签,且apk放在/system/priv-app
目录下 - 指定接收者.获取所有接收该广播的ResolveInfo,发送广播。