Show a notification if game is run as administrator

osu.Desktop/OsuGameDesktop.cs

@@ -7,6 +7,7 @@ using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Runtime.Versioning;
+using System.Security.Principal;
 using System.Threading.Tasks;
 using Microsoft.Win32;
 using osu.Desktop.Overlays;
@@ -20,6 +21,7 @@ using osu.Game.Screens.Menu;
 using osu.Game.Updater;
 using osu.Desktop.Windows;
 using osu.Framework.Threading;
+using osu.Game.Admin;
 using osu.Game.IO;
 
 namespace osu.Desktop
@@ -102,6 +104,8 @@ namespace osu.Desktop
             }
         }
 
+        protected override AdminChecker CreateAdminChecker() => new DesktopAdminChecker();
+
         protected override void LoadComplete()
         {
             base.LoadComplete();
@@ -180,5 +184,10 @@ namespace osu.Desktop
                 Task.Factory.StartNew(() => Import(paths), TaskCreationOptions.LongRunning);
             }
         }
+
+        private class DesktopAdminChecker : AdminChecker
+        {
+            protected override bool IsAdmin() => OperatingSystem.IsWindows() ? new WindowsPrincipal(WindowsIdentity.GetCurrent()).IsInRole(WindowsBuiltInRole.Administrator) : Mono.Unix.Native.Syscall.geteuid() == 0;
+        }
     }
 }

osu.Desktop/osu.Desktop.csproj

@@ -25,6 +25,7 @@
   </ItemGroup>
   <ItemGroup Label="Package References">
     <PackageReference Include="Microsoft.NETCore.Targets" Version="5.0.0" />
+    <PackageReference Include="Mono.Posix.NETStandard" Version="5.20.1-preview" />
     <PackageReference Include="System.IO.Packaging" Version="5.0.0" />
     <PackageReference Include="ppy.squirrel.windows" Version="1.9.0.5" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="2.2.6" />

osu.Game/Admin/AdminChecker.cs

@@ -0,0 +1,57 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Game.Graphics;
+using osu.Game.Overlays;
+using osu.Game.Overlays.Notifications;
+
+namespace osu.Game.Admin
+{
+    /// <summary>
+    /// Checks if the game is running with elevated privileges (as admin in Windows, root in Unix) and displays a warning notification if so.
+    /// </summary>
+    public class AdminChecker : CompositeDrawable
+    {
+        [Resolved]
+        protected NotificationOverlay Notifications { get; private set; }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+            if (IsAdmin())
+                Notifications.Post(new AdminNotification());
+        }
+
+        protected virtual bool IsAdmin() => false;
+
+        private class AdminNotification : SimpleNotification
+        {
+            public override bool IsImportant => true;
+
+            public AdminNotification()
+            {
+                bool isUnix = RuntimeInfo.IsUnix;
+                Text = $"Running osu! as {(isUnix ? "root" : "administrator")} does not improve performance and poses a security risk. Please run the game normally.";
+            }
+
+            [BackgroundDependencyLoader]
+            private void load(OsuColour colours, NotificationOverlay notificationOverlay)
+            {
+                Icon = FontAwesome.Solid.ShieldAlt;
+                IconBackgound.Colour = colours.YellowDark;
+
+                Activated = delegate
+                {
+                    notificationOverlay.Hide();
+                    return true;
+                };
+            }
+        }
+    }
+
+
+}

osu.Game/OsuGame.cs

@@ -28,6 +28,7 @@ using osu.Framework.Graphics.Sprites;
 using osu.Framework.Input;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Threading;
+using osu.Game.Admin;
 using osu.Game.Beatmaps;
 using osu.Game.Collections;
 using osu.Game.Graphics;
@@ -450,6 +451,8 @@ namespace osu.Game
 
         protected virtual UpdateManager CreateUpdateManager() => new UpdateManager();
 
+        protected virtual AdminChecker CreateAdminChecker() => new AdminChecker();
+
         protected override Container CreateScalingContainer() => new ScalingContainer(ScalingMode.Everything);
 
         #region Beatmap progression
@@ -673,6 +676,8 @@ namespace osu.Game
             // dependency on notification overlay, dependent by settings overlay
             loadComponentSingleFile(CreateUpdateManager(), Add, true);
 
+            loadComponentSingleFile(CreateAdminChecker(), Add, false);
+
             // overlay elements
             loadComponentSingleFile(new ManageCollectionsDialog(), overlayContent.Add, true);
             loadComponentSingleFile(beatmapListing = new BeatmapListingOverlay(), overlayContent.Add, true);