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Commit 6706c1ac authored by Hui Yu's avatar Hui Yu
Browse files

Background startForeground() improvement. 

Previously Service.startForeground() can be called from a background
service and startForeground()/stopForeground() can be called repeatly
from background. The BG-FGS-launch will add more restriction on this.

1. If the first 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 and mAllowStartForeground flags again.
2. At Service.stopForeground() call, mAllowWhileInUsePermissionInFgs and
mAllowStartForeground flags should be reset to false so FGS while-in-use
 permission and FGS BG start 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 and mAllowStartForeground
flags again.

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: Idc88f274c7a323d175d65bb47eca041772ae9bb7
parent e3e4c1f9

services/core/java/com/android/server/am/ActiveServices.java

+52 −0
Original line number Diff line number Diff line
@@ -1790,6 +1790,44 @@ public final class ActiveServices { 
                }



                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) {

                                setFgsRestrictionLocked(r.serviceInfo.packageName, r.app.getPid(),

                                        r.appInfo.uid, r.intent.getIntent(), r, false);

                                final String temp = "startForegroundDelayMs:" + delayMs;

                                if (r.mInfoAllowStartForeground != null) {

                                    r.mInfoAllowStartForeground += "; " + temp;

                                } else {

                                    r.mInfoAllowStartForeground = temp;

                                }

                                r.mLoggedInfoAllowStartForeground = false;

                            }

                        }

                    } 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.getPid(),

                                    r.appInfo.uid, r.intent.getIntent(), r, false);

                        }

                    }

                    logFgsBackgroundStart(r);

                    if (r.mAllowStartForeground == REASON_DENIED && isBgFgsRestrictionEnabled(r)) {

                        final String msg = "Service.startForeground() not allowed due to "
@@ -1843,6 +1881,7 @@ public final class ActiveServices { 
                            active.mNumActive++;

                        }

                        r.isForeground = true;

                        r.mStartForegroundCount++;

                        if (!stopProcStatsOp) {

                            ServiceState stracker = r.getTracker();

                            if (stracker != null) {
@@ -1901,6 +1940,7 @@ public final class ActiveServices { 
                    decActiveForegroundAppLocked(smap, r);

                }

                r.isForeground = false;

                resetFgsRestrictionLocked(r);

                ServiceState stracker = r.getTracker();

                if (stracker != null) {

                    stracker.setForeground(false, mAm.mProcessStats.getMemFactorLocked(),
@@ -3892,6 +3932,7 @@ public final class ActiveServices { 
        r.foregroundId = 0;

        r.foregroundNoti = null;

        r.mAllowWhileInUsePermissionInFgs = false;

        r.mAllowStartForeground = REASON_DENIED;



        // Clear start entries.

        r.clearDeliveredStartsLocked();
@@ -5430,6 +5471,7 @@ public final class ActiveServices { 
    private void setFgsRestrictionLocked(String callingPackage,

            int callingPid, int callingUid, Intent intent, ServiceRecord r,

            boolean allowBackgroundActivityStarts) {

        r.mLastSetFgsRestrictionTime = SystemClock.elapsedRealtime();

        // Check DeviceConfig flag.

        if (!mAm.mConstants.mFlagBackgroundFgsStartRestrictionEnabled) {

            r.mAllowWhileInUsePermissionInFgs = true;
@@ -5450,6 +5492,15 @@ public final class ActiveServices { 
        }

    }



    void resetFgsRestrictionLocked(ServiceRecord r) {

        r.mAllowWhileInUsePermissionInFgs = false;

        r.mAllowStartForeground = REASON_DENIED;

        r.mInfoAllowStartForeground = null;

        r.mInfoTempFgsAllowListReason = null;

        r.mLoggedInfoAllowStartForeground = false;

        r.mLastSetFgsRestrictionTime = 0;

    }



    boolean canStartForegroundServiceLocked(int callingPid, int callingUid, String callingPackage) {

        if (!mAm.mConstants.mFlagBackgroundFgsStartRestrictionEnabled) {

            return true;
@@ -5601,6 +5652,7 @@ public final class ActiveServices { 
                                        + ",callingUid:" + tempAllowListReason.mCallingUid))

                        + ">"

                        + "; targetSdkVersion:" + r.appInfo.targetSdkVersion

                        + "; startForegroundCount:" + r.mStartForegroundCount

                        + "]";

        if (!debugInfo.equals(r.mInfoAllowStartForeground)) {

            r.mLoggedInfoAllowStartForeground = false;

services/core/java/com/android/server/am/ActivityManagerConstants.java

+20 −1
Original line number Diff line number Diff line
@@ -96,6 +96,7 @@ final class ActivityManagerConstants extends ContentObserver { 
    static final String KEY_PROCESS_CRASH_COUNT_LIMIT = "process_crash_count_limit";

    static final String KEY_BOOT_TIME_TEMP_ALLOWLIST_DURATION = "boot_time_temp_allowlist_duration";

    static final String KEY_FG_TO_BG_FGS_GRACE_DURATION = "fg_to_bg_fgs_grace_duration";

    static final String KEY_FGS_START_FOREGROUND_TIMEOUT = "fgs_start_foreground_timeout";



    private static final int DEFAULT_MAX_CACHED_PROCESSES = 32;

    private static final long DEFAULT_BACKGROUND_SETTLE_TIME = 60*1000;
@@ -135,7 +136,7 @@ final class ActivityManagerConstants extends ContentObserver { 
    private static final int DEFAULT_PROCESS_CRASH_COUNT_LIMIT = 12;

    private static final int DEFAULT_BOOT_TIME_TEMP_ALLOWLIST_DURATION = 10 * 1000;

    private static final long DEFAULT_FG_TO_BG_FGS_GRACE_DURATION = 5 * 1000;



    private static final int DEFAULT_FGS_START_FOREGROUND_TIMEOUT_MS = 10 * 1000;



    // Flag stored in the DeviceConfig API.

    /**
@@ -396,6 +397,12 @@ final class ActivityManagerConstants extends ContentObserver { 
     */

    volatile long mFgToBgFgsGraceDuration = DEFAULT_FG_TO_BG_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;



    private final ActivityManagerService mService;

    private ContentResolver mResolver;

    private final KeyValueListParser mParser = new KeyValueListParser(',');
@@ -586,6 +593,9 @@ final class ActivityManagerConstants extends ContentObserver { 
                            case KEY_FG_TO_BG_FGS_GRACE_DURATION:

                                updateFgToBgFgsGraceDuration();

                                break;

                            case KEY_FGS_START_FOREGROUND_TIMEOUT:

                                updateFgsStartForegroundTimeout();

                                break;

                            default:

                                break;

                        }
@@ -869,6 +879,13 @@ final class ActivityManagerConstants extends ContentObserver { 
                DEFAULT_FG_TO_BG_FGS_GRACE_DURATION);

    }



    private void updateFgsStartForegroundTimeout() {

        mFgsStartForegroundTimeoutMs = DeviceConfig.getLong(

                DeviceConfig.NAMESPACE_ACTIVITY_MANAGER,

                KEY_FGS_START_FOREGROUND_TIMEOUT,

                DEFAULT_FGS_START_FOREGROUND_TIMEOUT_MS);

    }



    private void updateImperceptibleKillExemptions() {

        IMPERCEPTIBLE_KILL_EXEMPT_PACKAGES.clear();

        IMPERCEPTIBLE_KILL_EXEMPT_PACKAGES.addAll(mDefaultImperceptibleKillExemptPackages);
@@ -1071,6 +1088,8 @@ final class ActivityManagerConstants extends ContentObserver { 
        pw.println(mBootTimeTempAllowlistDuration);

        pw.print("  "); pw.print(KEY_FG_TO_BG_FGS_GRACE_DURATION); pw.print("=");

        pw.println(mFgToBgFgsGraceDuration);

        pw.print("  "); pw.print(KEY_FGS_START_FOREGROUND_TIMEOUT); pw.print("=");

        pw.println(mFgsStartForegroundTimeoutMs);



        pw.println();

        if (mOverrideMaxCachedProcesses >= 0) {

services/core/java/com/android/server/am/ServiceRecord.java

+9 −0
Original line number Diff line number Diff line
@@ -165,9 +165,16 @@ final class ServiceRecord extends Binder implements ComponentName.WithComponentN 
    // allow the service becomes foreground service? Service started from background may not be

    // allowed to become a foreground service.

    @PowerWhitelistManager.ReasonCode int mAllowStartForeground = REASON_DENIED;

    // Debug info why mAllowStartForeground is allowed or denied.

    String mInfoAllowStartForeground;

    // Debug info if mAllowStartForeground is allowed because of a temp-allowlist.

    FgsStartTempAllowList.TempFgsAllowListEntry mInfoTempFgsAllowListReason;

    // Is the same mInfoAllowStartForeground string has been logged before? Used for dedup.

    boolean mLoggedInfoAllowStartForeground;

    // The number of times Service.startForeground() is called;

    int mStartForegroundCount;

    // Last time mAllowWhileInUsePermissionInFgs or mAllowStartForeground is set.

    long mLastSetFgsRestrictionTime;



    String stringName;      // caching of toString
@@ -439,6 +446,8 @@ final class ServiceRecord extends Binder implements ComponentName.WithComponentN 
        pw.println(mRecentCallingUid);

        pw.print(prefix); pw.print("allowStartForeground=");

        pw.println(mAllowStartForeground);

        pw.print(prefix); pw.print("startForegroundCount=");

        pw.println(mStartForegroundCount);

        pw.print(prefix); pw.print("infoAllowStartForeground=");

        pw.println(mInfoAllowStartForeground);

        if (delayed) {