[Q]Sending non-protected broadcast问题分析

有同事遇到发送广播接收不到的问题，分析log发现是system进程发送non-protected广播的问题。Ams在发送广播时，对于systemApp会要求广播必须是声明在frameworks\base\core\res\AndroidManifest.xml里面的protected-broadcast。这样可以避免三方垃圾应用也发送这些广播来捣蛋。 

03-30 09:35:31.829  3827  4459 E ActivityManager: Sending non-protected broadcast 
droidlogic.hdr.policy.source_1 from system 4556:com.android.tv.settings/1000 pkg 
com.android.tv.settings

检查system进程权限的函数 

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());
        }
    }

 

AndroidManifest.xml的位置