Support for xdp_tx. (microsoft#498)

* xdp_tx

* Fix analysis error.

* update documentation.

* IPv6 tests.

* Apply suggestions from code review

docs/GettingStarted.md

@@ -41,6 +41,8 @@ This will build the following binaries:
                 and EbpCore and NetEbpfExt drivers to be loaded.
 * sample_ebpf_ext.sys: A sample eBPF extension driver that implements a test hook (for a test program type) and test helper functions.
 * sample_ext_app.exe : A sample application for testing the sample extension driver.
+* xdp_tests.exe : Application for testing various XDP functionalities.  This requires the EbpSvc service to be running,
+                and the EbpCore and NetEbpfExt drivers to be loaded on a remote system to test.
 
 and a few binaries just used for demo'ing eBPF functionality, as in the demo walkthrough discussed below:
 
@@ -153,3 +155,11 @@ Other useful options include:
 2.	-b to break into the debugger on test failure
 3.	-l to list test cases
 4.	Test_name to run a single test
+
+### xdp_tests.exe
+This application tests various XDP functionalities. It has the following tests:
+1. Reflection Test: This tests the XDP_TX functionality. The following steps show how to run the test:
+   1. On the system under test, install eBPF binaries (install-ebpf.bat).
+   2. Load the test eBPF program by running the following commands: `netsh`, `ebpf`, `add program reflect_packet.o xdp`.
+   3. From a remote host, run xdp_tests.exe and in `--remote-ip` parameter pass an IPv4 or IPv6 address of an Ethernet-like interface on the system under test in string format.
+   4. Unload the program from system under test by running `delete program reflect_packet.o xdp` on the netsh prompt.

ebpf-for-windows.sln

@@ -120,6 +120,8 @@ Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "sample_ext_app", "tests\sam
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "performance", "tests\performance\performance.vcxproj", "{724EB55A-CCFC-4662-92E3-B664CDA365E7}"
 EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "xdp_tests", "tests\xdp\xdp_tests.vcxproj", "{07DC6181-84A2-4A14-A806-5E9AF6C929C2}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|ARM = Debug|ARM
@@ -1084,6 +1086,34 @@ Global
 		{724EB55A-CCFC-4662-92E3-B664CDA365E7}.RelWithDebInfo|x64.Build.0 = Release|x64
 		{724EB55A-CCFC-4662-92E3-B664CDA365E7}.RelWithDebInfo|x86.ActiveCfg = Release|Win32
 		{724EB55A-CCFC-4662-92E3-B664CDA365E7}.RelWithDebInfo|x86.Build.0 = Release|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Debug|ARM.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Debug|ARM64.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Debug|x64.ActiveCfg = Debug|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Debug|x64.Build.0 = Debug|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Debug|x86.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Debug|x86.Build.0 = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|ARM.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|ARM.Build.0 = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|ARM64.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|ARM64.Build.0 = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|x64.ActiveCfg = Debug|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|x64.Build.0 = Debug|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|x86.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.MinSizeRel|x86.Build.0 = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Release|ARM.ActiveCfg = Release|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Release|ARM64.ActiveCfg = Release|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Release|x64.ActiveCfg = Release|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Release|x64.Build.0 = Release|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Release|x86.ActiveCfg = Release|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.Release|x86.Build.0 = Release|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|ARM.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|ARM.Build.0 = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|ARM64.ActiveCfg = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|ARM64.Build.0 = Debug|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|x64.ActiveCfg = Release|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|x64.Build.0 = Release|x64
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|x86.ActiveCfg = Release|Win32
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2}.RelWithDebInfo|x86.Build.0 = Release|Win32
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -1122,6 +1152,7 @@ Global
 		{C8D46543-5AE5-4E66-B9CE-8B84588B1C9E} = {492C9B22-9237-4996-9E33-CA14D3533616}
 		{7358D8BD-4123-4B2D-86C0-87F6BA6CED76} = {492C9B22-9237-4996-9E33-CA14D3533616}
 		{724EB55A-CCFC-4662-92E3-B664CDA365E7} = {492C9B22-9237-4996-9E33-CA14D3533616}
+		{07DC6181-84A2-4A14-A806-5E9AF6C929C2} = {492C9B22-9237-4996-9E33-CA14D3533616}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {3D5F862D-74C6-4357-9F95-0B152E33B7B8}

include/ebpf_nethooks.h

@@ -20,7 +20,8 @@ typedef struct xdp_md
 typedef enum _xdp_action
 {
     XDP_PASS = 1, ///< Allow the packet to pass.
-    XDP_DROP = 2  ///< Drop the packet.
+    XDP_DROP,     ///< Drop the packet.
+    XDP_TX        ///< Bounce the received packet back out the same NIC it arrived on.
 } xdp_action_t;
 
 /**

netebpfext/net_ebpf_ext.c

@@ -44,6 +44,8 @@
 #include "ebpf_windows.h"
 #include "ebpf_xdp_program_data.h"
 
+static HANDLE _net_ebpf_ext_l2_injection_handle = NULL;
+
 static ebpf_ext_attach_hook_provider_registration_t* _ebpf_xdp_hook_provider_registration = NULL;
 static ebpf_ext_attach_hook_provider_registration_t* _ebpf_bind_hook_provider_registration = NULL;
 static ebpf_extension_provider_t* _ebpf_xdp_program_info_provider = NULL;
@@ -293,8 +295,7 @@ NTSTATUS
 net_ebpf_ext_register_callouts(_Inout_ void* device_object)
 /* ++
 
-   This function registers dynamic callouts and filters that
-   FWPM_LAYER_INBOUND_MAC_FRAME_ETHERNET layer.
+   This function registers WFP callouts and filters at various layers.
 
    Callouts and filters will be removed during DriverUnload.
 
@@ -376,6 +377,11 @@ net_ebpf_ext_register_callouts(_Inout_ void* device_object)
     }
     is_in_transaction = FALSE;
 
+    // Create L2 injection handle.
+    status = FwpsInjectionHandleCreate(AF_LINK, FWPS_INJECTION_TYPE_L2, &_net_ebpf_ext_l2_injection_handle);
+    if (!NT_SUCCESS(status))
+        goto Exit;
+
 Exit:
 
     if (!NT_SUCCESS(status)) {
@@ -404,6 +410,48 @@ net_ebpf_ext_unregister_callouts(void)
             FwpsCalloutUnregisterById(_net_ebpf_ext_wfp_callout_state[index].assigned_callout_id);
         }
     }
+
+    FwpsInjectionHandleDestroy(_net_ebpf_ext_l2_injection_handle);
+}
+
+static void
+_net_ebpf_ext_l2_inject_complete(
+    _In_ const void* context, _Inout_ NET_BUFFER_LIST* packet_clone, BOOLEAN dispatch_level)
+{
+    UNREFERENCED_PARAMETER(context);
+    FwpsFreeCloneNetBufferList(packet_clone, dispatch_level);
+}
+
+static void
+_net_ebpf_ext_handle_xdp_tx(_Inout_ NET_BUFFER_LIST* packet, _In_ const FWPS_INCOMING_VALUES* incoming_fixed_values)
+{
+    NET_BUFFER_LIST* packet_clone = NULL;
+    NTSTATUS status = STATUS_SUCCESS;
+
+    uint32_t interface_index =
+        incoming_fixed_values->incomingValue[FWPS_FIELD_INBOUND_MAC_FRAME_NATIVE_INTERFACE_INDEX].value.uint32;
+    uint32_t ndis_port =
+        incoming_fixed_values->incomingValue[FWPS_FIELD_INBOUND_MAC_FRAME_NATIVE_NDIS_PORT].value.uint32;
+
+    status = FwpsAllocateCloneNetBufferList(packet, NULL, NULL, 0, &packet_clone);
+    if (status != STATUS_SUCCESS)
+        goto Exit;
+
+    status = FwpsInjectMacSendAsync(
+        _net_ebpf_ext_l2_injection_handle,
+        NULL,
+        0,
+        FWPS_LAYER_OUTBOUND_MAC_FRAME_NATIVE,
+        interface_index,
+        ndis_port,
+        packet_clone,
+        _net_ebpf_ext_l2_inject_complete,
+        NULL);
+
+    if (status != STATUS_SUCCESS)
+        goto Exit;
+Exit:
+    return;
 }
 
 static void
@@ -422,7 +470,7 @@ _net_ebpf_ext_layer_2_classify(
 -- */
 {
     FWP_ACTION_TYPE action = FWP_ACTION_PERMIT;
-    UNREFERENCED_PARAMETER(incoming_fixed_values);
+
     UNREFERENCED_PARAMETER(incoming_metadata_values);
     UNREFERENCED_PARAMETER(classify_context);
     UNREFERENCED_PARAMETER(filter);
@@ -459,8 +507,12 @@ _net_ebpf_ext_layer_2_classify(
         case XDP_PASS:
             action = FWP_ACTION_PERMIT;
             break;
+        case XDP_TX:
+            _net_ebpf_ext_handle_xdp_tx(nbl, incoming_fixed_values);
+            // Fall through.
         case XDP_DROP:
             action = FWP_ACTION_BLOCK;
+            classify_output->flags |= FWPS_CLASSIFY_OUT_FLAG_ABSORB;
             break;
         }
     }