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Limit the number of MediaSessions per uid

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This CL makes MediaSessionService counts the number of current
MediaSessions per uid, and throw exception to the app if the number
exceeds the limit.

Bug: 143672815
Test: atest MediaSessionTest
Change-Id: Ib3dd0f655d54f9ca436bcc3808e8eba241dfaacc
This commit is contained in:
Hyundo Moon
2020-01-20 10:45:36 +09:00
parent 29d2fc2f71
commit 745422a6a4
2 changed files with 40 additions and 14 deletions
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4
media/java/android/media/session/MediaSession.java
View File

@@ -146,6 +146,8 @@ public final class MediaSession {
* the system but will not be published until {@link #setActive(boolean)
* setActive(true)} is called. You must call {@link #release()} when
* finished with the session.
* <p>
* Note that {@link RuntimeException} will be thrown if an app creates too many sessions.
*
* @param context The context to use to create the session.
* @param tag A short name for debugging purposes.
@@ -163,6 +165,8 @@ public final class MediaSession {
* The {@code sessionInfo} can include additional unchanging information about this session.
* For example, it can include the version of the application, or the list of the custom
* commands that this session supports.
* <p>
* Note that {@link RuntimeException} will be thrown if an app creates too many sessions.
*
* @param context The context to use to create the session.
* @param tag A short name for debugging purposes.

50
services/core/java/com/android/server/media/MediaSessionService.java
View File

@@ -103,6 +103,7 @@ public class MediaSessionService extends SystemService implements Monitor {
private static final int WAKELOCK_TIMEOUT = 5000;
private static final int MEDIA_KEY_LISTENER_TIMEOUT = 1000;
private static final int SESSION_CREATION_LIMIT_PER_UID = 100;
private final Context mContext;
private final SessionManagerImpl mSessionManagerImpl;
@@ -428,6 +429,18 @@ public class MediaSessionService extends SystemService implements Monitor {
Log.d(TAG, "Destroying " + session);
}
FullUserRecord user = getFullUserRecordLocked(session.getUserId());
if (user != null) {
final int uid = session.getUid();
final int sessionCount = user.mUidToSessionCount.get(uid, 0);
if (sessionCount <= 0) {
Log.w(TAG, "destroySessionLocked: sessionCount should be positive. "
+ "sessionCount=" + sessionCount);
} else {
user.mUidToSessionCount.put(uid, sessionCount - 1);
}
}
if (mGlobalPrioritySession == session) {
mGlobalPrioritySession = null;
if (session.isActive() && user != null) {
@@ -490,6 +503,20 @@ public class MediaSessionService extends SystemService implements Monitor {
}
}
private boolean hasMediaControlPermission(int pid, int uid) {
// Check if it's system server or has MEDIA_CONTENT_CONTROL.
// Note that system server doesn't have MEDIA_CONTENT_CONTROL, so we need extra
// check here.
if (uid == Process.SYSTEM_UID || mContext.checkPermission(
android.Manifest.permission.MEDIA_CONTENT_CONTROL, pid, uid)
== PackageManager.PERMISSION_GRANTED) {
return true;
} else if (DEBUG) {
Log.d(TAG, "uid(" + uid + ") hasn't granted MEDIA_CONTENT_CONTROL");
}
return false;
}
/**
* This checks if the component is an enabled notification listener for the
* specified user. Enabled components may only operate on behalf of the user
@@ -544,6 +571,14 @@ public class MediaSessionService extends SystemService implements Monitor {
throw new RuntimeException("Media Session owner died prematurely.", e);
}
final int sessionCount = user.mUidToSessionCount.get(callerUid, 0);
if (sessionCount >= SESSION_CREATION_LIMIT_PER_UID
&& !hasMediaControlPermission(callerPid, callerUid)) {
throw new RuntimeException("Created too many sessions. count="
+ sessionCount + ")");
}
user.mUidToSessionCount.put(callerUid, sessionCount + 1);
user.mPriorityStack.addSession(session);
mHandler.postSessionsChanged(session);
@@ -723,6 +758,7 @@ public class MediaSessionService extends SystemService implements Monitor {
mOnMediaKeyEventDispatchedListeners = new HashMap<>();
private final HashMap<IBinder, OnMediaKeyEventSessionChangedListenerRecord>
mOnMediaKeyEventSessionChangedListeners = new HashMap<>();
private final SparseIntArray mUidToSessionCount = new SparseIntArray();
private PendingIntent mLastMediaButtonReceiver;
private ComponentName mRestoredMediaButtonReceiver;
@@ -1954,20 +1990,6 @@ public class MediaSessionService extends SystemService implements Monitor {
return resolvedUserId;
}
private boolean hasMediaControlPermission(int pid, int uid) {
// Check if it's system server or has MEDIA_CONTENT_CONTROL.
// Note that system server doesn't have MEDIA_CONTENT_CONTROL, so we need extra
// check here.
if (uid == Process.SYSTEM_UID || mContext.checkPermission(
android.Manifest.permission.MEDIA_CONTENT_CONTROL, pid, uid)
== PackageManager.PERMISSION_GRANTED) {
return true;
} else if (DEBUG) {
Log.d(TAG, "uid(" + uid + ") hasn't granted MEDIA_CONTENT_CONTROL");
}
return false;
}
private boolean hasEnabledNotificationListener(int resolvedUserId, String packageName)
throws RemoteException {
// You may not access another user's content as an enabled listener.