Add option to change unix socket permissions

There is probably no way to do it when creating the socket

Jellyfin.Server/Program.cs

@@ -5,6 +5,7 @@ using System.IO;
 using System.Linq;
 using System.Net;
 using System.Reflection;
+using System.Runtime.InteropServices;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -198,6 +199,13 @@ namespace Jellyfin.Server
                 try
                 {
                     await webHost.StartAsync(_tokenSource.Token).ConfigureAwait(false);
+
+                    if (startupConfig.UseUnixSocket() && Environment.OSVersion.Platform == PlatformID.Unix)
+                    {
+                        var socketPath = GetUnixSocketPath(startupConfig, appPaths);
+
+                        SetUnixSocketPermissions(startupConfig, socketPath);
+                    }
                 }
                 catch (Exception ex) when (ex is not TaskCanceledException)
                 {
@@ -327,20 +335,7 @@ namespace Jellyfin.Server
                     // Bind to unix socket (only on unix systems)
                     if (startupConfig.UseUnixSocket() && Environment.OSVersion.Platform == PlatformID.Unix)
                     {
-                        var socketPath = startupConfig.GetUnixSocketPath();
-                        if (string.IsNullOrEmpty(socketPath))
-                        {
-                            var xdgRuntimeDir = Environment.GetEnvironmentVariable("XDG_RUNTIME_DIR");
-                            if (xdgRuntimeDir == null)
-                            {
-                                // Fall back to config dir
-                                socketPath = Path.Join(appPaths.ConfigurationDirectoryPath, "socket.sock");
-                            }
-                            else
-                            {
-                                socketPath = Path.Join(xdgRuntimeDir, "jellyfin-socket");
-                            }
-                        }
+                        var socketPath = GetUnixSocketPath(startupConfig, appPaths);
 
                         // Workaround for https://github.com/aspnet/AspNetCore/issues/14134
                         if (File.Exists(socketPath))
@@ -664,5 +659,49 @@ namespace Jellyfin.Server
 
             return "\"" + arg + "\"";
         }
+
+        private static string GetUnixSocketPath(IConfiguration startupConfig, IApplicationPaths appPaths)
+        {
+            var socketPath = startupConfig.GetUnixSocketPath();
+
+            if (string.IsNullOrEmpty(socketPath))
+            {
+                var xdgRuntimeDir = Environment.GetEnvironmentVariable("XDG_RUNTIME_DIR");
+                var socketFile = "jellyfin.sock";
+                if (xdgRuntimeDir == null)
+                {
+                    // Fall back to config dir
+                    socketPath = Path.Join(appPaths.ConfigurationDirectoryPath, socketFile);
+                }
+                else
+                {
+                    socketPath = Path.Join(xdgRuntimeDir, socketFile);
+                }
+            }
+
+            return socketPath;
+        }
+
+        private static void SetUnixSocketPermissions(IConfiguration startupConfig, string socketPath)
+        {
+            var socketPerms = startupConfig.GetUnixSocketPermissions();
+
+            if (!string.IsNullOrEmpty(socketPerms))
+            {
+                [DllImport("libc")]
+                static extern int chmod(string pathname, int mode);
+
+                var exitCode = chmod(socketPath, Convert.ToInt32(socketPerms, 8));
+
+                if (exitCode < 0)
+                {
+                    _logger.LogError("Failed to set Kestrel unix socket permissions to {SocketPerms}, return code: {ExitCode}", socketPerms, exitCode);
+                }
+                else
+                {
+                    _logger.LogInformation("Kestrel unix socket permissions set to {SocketPerms}", socketPerms);
+                }
+            }
+        }
     }
 }

MediaBrowser.Controller/Extensions/ConfigurationExtensions.cs

@@ -49,6 +49,11 @@ namespace MediaBrowser.Controller.Extensions
         /// </summary>
         public const string UnixSocketPathKey = "kestrel:socketPath";
 
+        /// <summary>
+        /// The permissions for the unix socket.
+        /// </summary>
+        public const string UnixSocketPermissionsKey = "kestrel:socketPermissions";
+
         /// <summary>
         /// Gets a value indicating whether the application should host static web content from the <see cref="IConfiguration"/>.
         /// </summary>
@@ -97,5 +102,13 @@ namespace MediaBrowser.Controller.Extensions
         /// <returns>The unix socket path.</returns>
         public static string GetUnixSocketPath(this IConfiguration configuration)
             => configuration[UnixSocketPathKey];
+
+        /// <summary>
+        /// Gets the permissions for the unix socket from the <see cref="IConfiguration" />.
+        /// </summary>
+        /// <param name="configuration">The configuration to read the setting from.</param>
+        /// <returns>The unix socket permissions.</returns>
+        public static string GetUnixSocketPermissions(this IConfiguration configuration)
+            => configuration[UnixSocketPermissionsKey];
     }
 }