BG-FGS-start while-in-use permission restriction improvement.

Hui Yu · BayerischeMotorenWerke · commit e39d90308208 · 2022-05-03T20:32:32.000+07:00
[This is a resbumit, previous fix ag/I0aca484e5a0dd051bbeac379d30b0fb4ecfa2da0 was reverted because the incorrect resetFgsRestrictionLocked() call] Foreground service started from background shall not have while-in-use access like location/camera/microphone. Previously we set mAllowWhileInUsePermissionInFgs only at service start by startService() or bindService() command. But after service start, the Service.startForeground() call may be some time later and at that time the caller may not be in the foreground any more. This CL will add further restriction on that. 1. If the first Service.startForeground() call is more than 10 seconds (can be configured by DeviceConfig key "fgs_start_foreground_timeout") after the Context.startService() call, check the service's app proc state and set mAllowWhileInUsePermissionInFgs again. 2. At Service.stopForeground() call, mAllowWhileInUsePermissionInFgs should be reset to false so FGS while-in-use permission is not allowed. 3. After Context.startForegroundService()(or Context.startService()) -> Service.startForeground() -> Service.stopForeground(), the second or more times Service.startForeground() is called, check the service's app proc state and set mAllowWhileInUsePermissionInFgs again. This CL is the backport of ag/Idc88f274c7a323d175d65bb47eca041772ae9bb7 from S branch. Bug: 183147114 Bug: 183204439 Test: atest cts/tests/app/src/android/app/cts/ActivityManagerFgsBgStartTest.java#testStartForegroundTimeout Test: atest cts/tests/app/src/android/app/cts/ActivityManagerFgsBgStartTest.java#testSecondStartForeground Change-Id: Ie8712b8efe85aa8a6769b811c85a29c4013e58b9 Merged-In: Idc88f274c7a323d175d65bb47eca041772ae9bb7 (cherry picked from commit d5abccf) Merged-In:Ie8712b8efe85aa8a6769b811c85a29c4013e58b9
diff --git a/services/core/java/com/android/server/am/ActiveServices.java b/services/core/java/com/android/server/am/ActiveServices.java
@@ -734,11 +734,8 @@ ComponentName startServiceLocked(IApplicationThread caller, Intent service, Stri
         }
         ComponentName cmp = startServiceInnerLocked(smap, service, r, callerFg, addToStarting);
 
-        if (!r.mAllowWhileInUsePermissionInFgs) {
-            r.mAllowWhileInUsePermissionInFgs =
-                    shouldAllowWhileInUsePermissionInFgsLocked(callingPackage, callingPid,
-                            callingUid, service, r, allowBackgroundActivityStarts);
-        }
+        setFgsRestrictionLocked(callingPackage, callingPid, callingUid, r,
+                allowBackgroundActivityStarts);
 
         return cmp;
     }
@@ -1411,14 +1408,6 @@ private void setServiceForegroundInnerLocked(final ServiceRecord r, int id,
                         +  String.format("0x%08X", manifestType)
                         + " in service element of manifest file");
                 }
-                // If the foreground service is not started from TOP process, do not allow it to
-                // have while-in-use location/camera/microphone access.
-                if (!r.mAllowWhileInUsePermissionInFgs) {
-                    Slog.w(TAG,
-                            "Foreground service started from background can not have "
-                                    + "location/camera/microphone access: service "
-                                    + r.shortInstanceName);
-                }
             }
             boolean alreadyStartedOp = false;
             boolean stopProcStatsOp = false;
@@ -1466,6 +1455,56 @@ && appRestrictedAnyInBackground(r.appInfo.uid, r.packageName)) {
                     ignoreForeground = true;
                 }
 
+                if (!ignoreForeground) {
+                    if (r.mStartForegroundCount == 0) {
+                        /*
+                        If the service was started with startService(), not
+                        startForegroundService(), and if startForeground() isn't called within
+                        mFgsStartForegroundTimeoutMs, then we check the state of the app
+                        (who owns the service, which is the app that called startForeground())
+                        again. If the app is in the foreground, or in any other cases where
+                        FGS-starts are allowed, then we still allow the FGS to be started.
+                        Otherwise, startForeground() would fail.
+
+                        If the service was started with startForegroundService(), then the service
+                        must call startForeground() within a timeout anyway, so we don't need this
+                        check.
+                        */
+                        if (!r.fgRequired) {
+                            final long delayMs = SystemClock.elapsedRealtime() - r.createRealTime;
+                            if (delayMs > mAm.mConstants.mFgsStartForegroundTimeoutMs) {
+                                resetFgsRestrictionLocked(r);
+                                setFgsRestrictionLocked(r.serviceInfo.packageName, r.app.pid,
+                                        r.appInfo.uid, r, false);
+                                EventLog.writeEvent(0x534e4554, "183147114",
+                                        r.appInfo.uid,
+                                        "call setFgsRestrictionLocked again due to "
+                                                + "startForegroundTimeout");
+                            }
+                        }
+                    } else if (r.mStartForegroundCount >= 1) {
+                        // The second or later time startForeground() is called after service is
+                        // started. Check for app state again.
+                        final long delayMs = SystemClock.elapsedRealtime() -
+                                r.mLastSetFgsRestrictionTime;
+                        if (delayMs > mAm.mConstants.mFgsStartForegroundTimeoutMs) {
+                            setFgsRestrictionLocked(r.serviceInfo.packageName, r.app.pid,
+                                    r.appInfo.uid, r, false);
+                            EventLog.writeEvent(0x534e4554, "183147114", r.appInfo.uid,
+                                    "call setFgsRestrictionLocked for "
+                                            + (r.mStartForegroundCount + 1) + "th startForeground");
+                        }
+                    }
+                    // If the foreground service is not started from TOP process, do not allow it to
+                    // have while-in-use location/camera/microphone access.
+                    if (!r.mAllowWhileInUsePermissionInFgs) {
+                        Slog.w(TAG,
+                                "Foreground service started from background can not have "
+                                        + "location/camera/microphone access: service "
+                                        + r.shortInstanceName);
+                    }
+                }
+
                 // Apps under strict background restrictions simply don't get to have foreground
                 // services, so now that we've enforced the startForegroundService() contract
                 // we only do the machinery of making the service foreground when the app
@@ -1501,6 +1540,7 @@ && appRestrictedAnyInBackground(r.appInfo.uid, r.packageName)) {
                             active.mNumActive++;
                         }
                         r.isForeground = true;
+                        r.mStartForegroundCount++;
                         if (!stopProcStatsOp) {
                             ServiceState stracker = r.getTracker();
                             if (stracker != null) {
@@ -1559,6 +1599,7 @@ && appRestrictedAnyInBackground(r.appInfo.uid, r.packageName)) {
                     decActiveForegroundAppLocked(smap, r);
                 }
                 r.isForeground = false;
+                resetFgsRestrictionLocked(r);
                 ServiceState stracker = r.getTracker();
                 if (stracker != null) {
                     stracker.setForeground(false, mAm.mProcessStats.getMemFactorLocked(),
@@ -2118,12 +2159,7 @@ public void run() {
                 }
             }
 
-            if (!s.mAllowWhileInUsePermissionInFgs) {
-                s.mAllowWhileInUsePermissionInFgs =
-                        shouldAllowWhileInUsePermissionInFgsLocked(callingPackage,
-                                callingPid, callingUid,
-                                service, s, false);
-            }
+            setFgsRestrictionLocked(callingPackage, callingPid, callingUid, s, false);
 
             if (s.app != null) {
                 if ((flags&Context.BIND_TREAT_LIKE_ACTIVITY) != 0) {
@@ -3419,7 +3455,7 @@ private final void bringDownServiceLocked(ServiceRecord r) {
         r.isForeground = false;
         r.foregroundId = 0;
         r.foregroundNoti = null;
-        r.mAllowWhileInUsePermissionInFgs = false;
+        resetFgsRestrictionLocked(r);
 
         // Clear start entries.
         r.clearDeliveredStartsLocked();
@@ -4900,7 +4936,7 @@ private void dumpService(String prefix, FileDescriptor fd, PrintWriter pw,
      * @return true if allow, false otherwise.
      */
     private boolean shouldAllowWhileInUsePermissionInFgsLocked(String callingPackage,
-            int callingPid, int callingUid, Intent intent, ServiceRecord r,
+            int callingPid, int callingUid, ServiceRecord r,
             boolean allowBackgroundActivityStarts) {
         // Is the background FGS start restriction turned on?
         if (!mAm.mConstants.mFlagBackgroundFgsStartRestrictionEnabled) {
@@ -4982,4 +5018,33 @@ private boolean shouldAllowWhileInUsePermissionInFgsLocked(String callingPackage
         }
         return false;
     }
+
+    boolean canAllowWhileInUsePermissionInFgsLocked(int callingPid, int callingUid,
+            String callingPackage) {
+        return shouldAllowWhileInUsePermissionInFgsLocked(
+                callingPackage, callingPid, callingUid, null, false);
+    }
+
+    /**
+     * In R, mAllowWhileInUsePermissionInFgs is to allow while-in-use permissions in foreground
+     *  service or not. while-in-use permissions in FGS started from background might be restricted.
+     * @param callingPackage caller app's package name.
+     * @param callingUid caller app's uid.
+     * @param r the service to start.
+     * @return true if allow, false otherwise.
+     */
+    private void setFgsRestrictionLocked(String callingPackage,
+            int callingPid, int callingUid, ServiceRecord r,
+            boolean allowBackgroundActivityStarts) {
+        r.mLastSetFgsRestrictionTime = SystemClock.elapsedRealtime();
+        if (!r.mAllowWhileInUsePermissionInFgs) {
+            r.mAllowWhileInUsePermissionInFgs = shouldAllowWhileInUsePermissionInFgsLocked(
+                    callingPackage, callingPid, callingUid, r, allowBackgroundActivityStarts);
+        }
+    }
+
+    private void resetFgsRestrictionLocked(ServiceRecord r) {
+        r.mAllowWhileInUsePermissionInFgs = false;
+        r.mLastSetFgsRestrictionTime = 0;
+    }
 }
diff --git a/services/core/java/com/android/server/am/ActivityManagerConstants.java b/services/core/java/com/android/server/am/ActivityManagerConstants.java
@@ -88,6 +88,7 @@ final class ActivityManagerConstants extends ContentObserver {
     static final String KEY_PROCESS_START_ASYNC = "process_start_async";
     static final String KEY_MEMORY_INFO_THROTTLE_TIME = "memory_info_throttle_time";
     static final String KEY_TOP_TO_FGS_GRACE_DURATION = "top_to_fgs_grace_duration";
+    static final String KEY_FGS_START_FOREGROUND_TIMEOUT = "fgs_start_foreground_timeout";
     static final String KEY_PENDINGINTENT_WARNING_THRESHOLD = "pendingintent_warning_threshold";
 
     private static final int DEFAULT_MAX_CACHED_PROCESSES = 32;
@@ -121,6 +122,7 @@ final class ActivityManagerConstants extends ContentObserver {
     private static final boolean DEFAULT_PROCESS_START_ASYNC = true;
     private static final long DEFAULT_MEMORY_INFO_THROTTLE_TIME = 5*60*1000;
     private static final long DEFAULT_TOP_TO_FGS_GRACE_DURATION = 15 * 1000;
+    private static final int DEFAULT_FGS_START_FOREGROUND_TIMEOUT_MS = 10 * 1000;
     private static final int DEFAULT_PENDINGINTENT_WARNING_THRESHOLD = 2000;
 
     // Flag stored in the DeviceConfig API.
@@ -273,6 +275,12 @@ final class ActivityManagerConstants extends ContentObserver {
     // this long.
     public long TOP_TO_FGS_GRACE_DURATION = DEFAULT_TOP_TO_FGS_GRACE_DURATION;
 
+    /**
+     * When service started from background, before the timeout it can be promoted to FGS by calling
+     * Service.startForeground().
+     */
+    volatile long mFgsStartForegroundTimeoutMs = DEFAULT_FGS_START_FOREGROUND_TIMEOUT_MS;
+
     // Indicates whether the activity starts logging is enabled.
     // Controlled by Settings.Global.ACTIVITY_STARTS_LOGGING_ENABLED
     volatile boolean mFlagActivityStartsLoggingEnabled;
@@ -421,6 +429,9 @@ public void onPropertiesChanged(Properties properties) {
                             case KEY_MIN_ASSOC_LOG_DURATION:
                                 updateMinAssocLogDuration();
                                 break;
+                            case KEY_FGS_START_FOREGROUND_TIMEOUT:
+                                updateFgsStartForegroundTimeout();
+                                break;
                             default:
                                 break;
                         }
@@ -697,6 +708,13 @@ private void updateMinAssocLogDuration() {
                 /* defaultValue */ DEFAULT_MIN_ASSOC_LOG_DURATION);
     }
 
+    private void updateFgsStartForegroundTimeout() {
+        mFgsStartForegroundTimeoutMs = DeviceConfig.getLong(
+                DeviceConfig.NAMESPACE_ACTIVITY_MANAGER,
+                KEY_FGS_START_FOREGROUND_TIMEOUT,
+                DEFAULT_FGS_START_FOREGROUND_TIMEOUT_MS);
+    }
+
     void dump(PrintWriter pw) {
         pw.println("ACTIVITY MANAGER SETTINGS (dumpsys activity settings) "
                 + Settings.Global.ACTIVITY_MANAGER_CONSTANTS + ":");
@@ -769,6 +787,8 @@ void dump(PrintWriter pw) {
         pw.println(Arrays.toString(IMPERCEPTIBLE_KILL_EXEMPT_PACKAGES.toArray()));
         pw.print("  "); pw.print(KEY_MIN_ASSOC_LOG_DURATION); pw.print("=");
         pw.println(MIN_ASSOC_LOG_DURATION);
+        pw.print("  "); pw.print(KEY_FGS_START_FOREGROUND_TIMEOUT); pw.print("=");
+        pw.println(mFgsStartForegroundTimeoutMs);
 
         pw.println();
         if (mOverrideMaxCachedProcesses >= 0) {
diff --git a/services/core/java/com/android/server/am/ServiceRecord.java b/services/core/java/com/android/server/am/ServiceRecord.java
@@ -142,6 +142,10 @@ final class ServiceRecord extends Binder implements ComponentName.WithComponentN
     // allow while-in-use permissions in foreground service or not.
     // while-in-use permissions in FGS started from background might be restricted.
     boolean mAllowWhileInUsePermissionInFgs;
+    // The number of times Service.startForeground() is called;
+    int mStartForegroundCount;
+    // Last time mAllowWhileInUsePermissionInFgs is set.
+    long mLastSetFgsRestrictionTime;
 
     // the most recent package that start/bind this service.
     String mRecentCallingPackage;
@@ -406,6 +410,8 @@ void dump(PrintWriter pw, String prefix) {
         }
         pw.print(prefix); pw.print("allowWhileInUsePermissionInFgs=");
                 pw.println(mAllowWhileInUsePermissionInFgs);
+        pw.print(prefix); pw.print("startForegroundCount=");
+        pw.println(mStartForegroundCount);
         pw.print(prefix); pw.print("recentCallingPackage=");
                 pw.println(mRecentCallingPackage);
         if (delayed) {
