Disable socket inheritance on Windows and macOS

src/Common/src/Interop/Windows/Winsock/Interop.SocketConstructorFlags.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Net.Sockets;
+using System.Runtime.InteropServices;
+
+internal static partial class Interop
+{
+    internal static partial class Winsock
+    {
+        // Used as last parameter to WSASocket call.
+        [Flags]
+        internal enum SocketConstructorFlags
+        {
+            WSA_FLAG_OVERLAPPED = 0x01,
+            WSA_FLAG_MULTIPOINT_C_ROOT = 0x02,
+            WSA_FLAG_MULTIPOINT_C_LEAF = 0x04,
+            WSA_FLAG_MULTIPOINT_D_ROOT = 0x08,
+            WSA_FLAG_MULTIPOINT_D_LEAF = 0x10,
+            WSA_FLAG_NO_HANDLE_INHERIT = 0x80,
+        }
+    }
+}

src/Common/src/Interop/Windows/Winsock/Interop.WSASocketW.SafeCloseSocket.cs

@@ -10,17 +10,6 @@ internal static partial class Interop
 {
     internal static partial class Winsock
     {
-        // Used as last parameter to WSASocket call.
-        [Flags]
-        internal enum SocketConstructorFlags
-        {
-            WSA_FLAG_OVERLAPPED = 0x01,
-            WSA_FLAG_MULTIPOINT_C_ROOT = 0x02,
-            WSA_FLAG_MULTIPOINT_C_LEAF = 0x04,
-            WSA_FLAG_MULTIPOINT_D_ROOT = 0x08,
-            WSA_FLAG_MULTIPOINT_D_LEAF = 0x10,
-        }
-
         [DllImport(Interop.Libraries.Ws2_32, CharSet = CharSet.Unicode, SetLastError = true)]
         internal static extern SafeCloseSocket.InnerSafeCloseSocket WSASocketW(
                                                 [In] AddressFamily addressFamily,

src/Common/src/System/Net/SafeCloseSocket.Windows.cs

@@ -217,7 +217,7 @@ private SocketError InnerReleaseHandle()
 
             internal static InnerSafeCloseSocket CreateWSASocket(AddressFamily addressFamily, SocketType socketType, ProtocolType protocolType)
             {
-                InnerSafeCloseSocket result = Interop.Winsock.WSASocketW(addressFamily, socketType, protocolType, IntPtr.Zero, 0, Interop.Winsock.SocketConstructorFlags.WSA_FLAG_OVERLAPPED);
+                InnerSafeCloseSocket result = Interop.Winsock.WSASocketW(addressFamily, socketType, protocolType, IntPtr.Zero, 0, Interop.Winsock.SocketConstructorFlags.WSA_FLAG_OVERLAPPED | Interop.Winsock.SocketConstructorFlags.WSA_FLAG_NO_HANDLE_INHERIT);
                 if (result.IsInvalid)
                 {
                     result.SetHandleAsInvalid();

src/Common/src/System/Net/SocketProtocolSupportPal.Windows.cs

@@ -63,7 +63,7 @@ private static bool IsProtocolSupported(AddressFamily af)
 
             try
             {
-                s = Interop.Winsock.WSASocketW(af, SocketType.Dgram, 0, IntPtr.Zero, 0, 0);
+                s = Interop.Winsock.WSASocketW(af, SocketType.Dgram, 0, IntPtr.Zero, 0, (int)Interop.Winsock.SocketConstructorFlags.WSA_FLAG_NO_HANDLE_INHERIT);
 
                 if (s == IntPtr.Zero)
                 {

src/Native/Unix/System.Native/pal_networking.c

@@ -1978,7 +1978,15 @@ int32_t SystemNative_Socket(int32_t addressFamily, int32_t socketType, int32_t p
     platformSocketType |= SOCK_CLOEXEC;
 #endif
     *createdSocket = socket(platformAddressFamily, platformSocketType, platformProtocolType);
-    return *createdSocket != -1 ? Error_SUCCESS : SystemNative_ConvertErrorPlatformToPal(errno);
+    if (*createdSocket == -1)
+    {
+        return SystemNative_ConvertErrorPlatformToPal(errno);
+    }
+
+#ifndef SOCK_CLOEXEC
+    fcntl(ToFileDescriptor(*createdSocket), F_SETFD, FD_CLOEXEC); // ignore any failures; this is best effort
+#endif
+    return Error_SUCCESS;
 }
 
 int32_t SystemNative_GetAtOutOfBandMark(intptr_t socket, int32_t* atMark)

src/System.Net.NameResolution/src/System.Net.NameResolution.csproj

@@ -103,6 +103,9 @@
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.WSASocketW.cs">
       <Link>Interop\Windows\Winsock\Interop.WSASocketW.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs">
+      <Link>Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)\System\Net\Sockets\ProtocolFamily.cs">
       <Link>Common\System\Net\Sockets\ProtocolFamily.cs</Link>
     </Compile>
@@ -198,4 +201,4 @@
     <Reference Include="System.Threading.Overlapped" />
     <Reference Include="System.Threading.Tasks" />
   </ItemGroup>
-</Project>
+</Project>

src/System.Net.NameResolution/tests/PalTests/System.Net.NameResolution.Pal.Tests.csproj

@@ -108,6 +108,9 @@
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.WSASocketW.cs">
       <Link>Interop\Windows\Winsock\Interop.WSASocketW.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs">
+      <Link>Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)\System\Net\Sockets\ProtocolFamily.cs">
       <Link>Common\System\Net\Sockets\ProtocolFamily.cs</Link>
     </Compile>
@@ -183,4 +186,4 @@
       <Link>Interop\Unix\System.Native\Interop.SocketAddress.cs</Link>
     </Compile>
   </ItemGroup>
-</Project>
+</Project>

src/System.Net.NetworkInformation/src/System.Net.NetworkInformation.csproj

@@ -206,6 +206,9 @@
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.WSASocketW.SafeCloseSocket.cs">
       <Link>Interop\Windows\Winsock\Interop.WSASocketW.SafeCloseSocket.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs">
+      <Link>Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\WSABuffer.cs">
       <Link>Interop\Windows\Winsock\WSABuffer.cs</Link>
     </Compile>
@@ -358,4 +361,4 @@
   <ItemGroup Condition="'$(TargetsLinux)' == 'true'">
     <Reference Include="System.Threading.Timer" />
   </ItemGroup>
-</Project>
+</Project>

src/System.Net.Ping/src/System.Net.Ping.csproj

@@ -123,6 +123,9 @@
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.WSASocketW.cs">
       <Link>Common\Interop\Windows\Winsock\Interop.WSASocketW.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs">
+      <Link>Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs</Link>
+    </Compile>
     <!-- System.Net.Internals -->
     <Compile Include="$(CommonPath)\System\Net\Sockets\SocketType.cs">
       <Link>Common\System\Net\Sockets\SocketType.cs</Link>
@@ -151,4 +154,4 @@
     <Reference Include="System.IO.FileSystem" />
     <Reference Include="System.Runtime.InteropServices.RuntimeInformation" />
   </ItemGroup>
-</Project>
+</Project>

src/System.Net.Sockets/src/System.Net.Sockets.csproj

@@ -228,6 +228,9 @@
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.WSASocketW.SafeCloseSocket.cs">
       <Link>Interop\Windows\Winsock\Interop.WSASocketW.SafeCloseSocket.cs</Link>
     </Compile>
+    <Compile Include="$(CommonPath)\Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs">
+      <Link>Interop\Windows\Winsock\Interop.SocketConstructorFlags.cs</Link>
+    </Compile>
     <Compile Include="$(CommonPath)\Interop\Windows\Winsock\SafeNativeOverlapped.cs">
       <Link>Interop\Windows\Winsock\SafeNativeOverlapped.cs</Link>
     </Compile>
@@ -403,4 +406,4 @@
   <ItemGroup Condition="'$(TargetsUnix)' == 'true'">
     <Reference Include="System.Threading.ThreadPool" />
   </ItemGroup>
-</Project>
+</Project>

src/System.Net.Sockets/tests/FunctionalTests/CreateSocketTests.cs

@@ -2,11 +2,15 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Diagnostics;
+using System.IO;
+using System.IO.Pipes;
+using System.Threading.Tasks;
 using Xunit;
 
 namespace System.Net.Sockets.Tests
 {
-    public class CreateSocket
+    public class CreateSocket : RemoteExecutorTestBase
     {
         public static object[][] DualModeSuccessInputs = {
             new object[] { SocketType.Stream, ProtocolType.Tcp },
@@ -89,9 +93,95 @@ public void Ctor_Failure(AddressFamily addressFamily, SocketType socketType, Pro
         [ConditionalTheory(nameof(SupportsRawSockets))]
         public void Ctor_Raw_Success(AddressFamily addressFamily, ProtocolType protocolType)
         {
-           using (new Socket(addressFamily, SocketType.Raw, protocolType))
-           {
-           }
+            using (new Socket(addressFamily, SocketType.Raw, protocolType))
+            {
+            }
+        }
+
+        [SkipOnTargetFramework(TargetFrameworkMonikers.NetFramework, "Sockets are still inheritable on netfx: https://github.com/dotnet/corefx/pull/32903")]
+        [Theory]
+        [InlineData(true, 0)] // Accept
+        [InlineData(false, 0)]
+        [InlineData(true, 1)] // AcceptAsync
+        [InlineData(false, 1)]
+        [InlineData(true, 2)] // Begin/EndAccept
+        [InlineData(false, 2)]
+        public void CtorAndAccept_SocketNotKeptAliveViaInheritance(bool validateClientOuter, int acceptApiOuter)
+        {
+            // Run the test in another process so as to not have trouble with other tests
+            // launching child processes that might impact inheritance.
+            RemoteInvoke((validateClientString, acceptApiString) =>
+            {
+                bool validateClient = bool.Parse(validateClientString);
+                int acceptApi = int.Parse(acceptApiString);
+
+                // Create a listening server.
+                using (var listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
+                {
+                    listener.Bind(new IPEndPoint(IPAddress.Loopback, 0));
+                    listener.Listen(int.MaxValue);
+                    EndPoint ep = listener.LocalEndPoint;
+
+                    // Create a client and connect to that listener.
+                    using (var client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
+                    {
+                        client.Connect(ep);
+
+                        // Accept the connection using one of multiple accept mechanisms.
+                        Socket server =
+                            acceptApi == 0 ? listener.Accept() :
+                            acceptApi == 1 ? listener.AcceptAsync().GetAwaiter().GetResult() :
+                            acceptApi == 2 ? Task.Factory.FromAsync(listener.BeginAccept, listener.EndAccept, null).GetAwaiter().GetResult() :
+                            throw new Exception($"Unexpected {nameof(acceptApi)}: {acceptApi}");
+
+                        // Get streams for the client and server, and create a pipe that we'll use
+                        // to communicate with a child process.
+                        using (var serverStream = new NetworkStream(server, ownsSocket: true))
+                        using (var clientStream = new NetworkStream(client, ownsSocket: true))
+                        using (var serverPipe = new AnonymousPipeServerStream(PipeDirection.Out, HandleInheritability.Inheritable))
+                        {
+                            // Create a child process that blocks waiting to receive a signal on the anonymous pipe.
+                            // The whole purpose of the child is to test whether handles are inherited, so we
+                            // keep the child process alive until we're done validating that handles close as expected.
+                            using (RemoteInvoke(clientPipeHandle =>
+                                   {
+                                       using (var clientPipe = new AnonymousPipeClientStream(PipeDirection.In, clientPipeHandle))
+                                       {
+                                           Assert.Equal(42, clientPipe.ReadByte());
+                                       }
+                                   }, serverPipe.GetClientHandleAsString()))
+                            {
+                                if (validateClient) // Validate that the child isn't keeping alive the "new Socket" for the client
+                                {
+                                    // Send data from the server to client, then validate the client gets EOF when the server closes.
+                                    serverStream.WriteByte(84);
+                                    Assert.Equal(84, clientStream.ReadByte());
+                                    serverStream.Close();
+                                    Assert.Equal(-1, clientStream.ReadByte());
+                                }
+                                else // Validate that the child isn't keeping alive the "listener.Accept" for the server
+                                {
+                                    // Send data from the client to server, then validate the server gets EOF when the client closes.
+                                    clientStream.WriteByte(84);
+                                    Assert.Equal(84, serverStream.ReadByte());
+                                    clientStream.Close();
+                                    Assert.Equal(-1, serverStream.ReadByte());
+                                }
+
+                                // And validate that we after closing the listening socket, we're not able to connect.
+                                listener.Dispose();
+                                using (var tmpClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
+                                {
+                                    Assert.ThrowsAny<SocketException>(() => tmpClient.Connect(ep));
+                                }
+
+                                // Let the child process terminate.
+                                serverPipe.WriteByte(42);
+                            }
+                        }
+                    }
+                }
+            }, validateClientOuter.ToString(), acceptApiOuter.ToString()).Dispose();
         }
     }
 }