datapath-windows: Release WFP allocated objects

Filter and sublayer WFP objects are created when the filter attach routine
is called and the tunnel filter is initialized, and they are released
in the uninitialize part. But the release part is done indirectly, through
the FwpmEngineClose function call which releases the latter objects when
the tunnel is uninitialized at filter detach.

We need to properly release the created objects and not rely that
FwpmEngineClose function does this for us, because if we decide to keep
the engine opened passed the filter detach those objects will continue to
exist.

Even though the FwpmEngineClose function releases the latter objects, we
still need this and the reason will became obvious in the next patch.

Signed-off-by: Sorin Vinturis <[email protected]>
Acked-by: Nithin Raju <[email protected]>
Signed-off-by: Ben Pfaff <[email protected]>

datapath-windows/ovsext/TunnelFilter.c

@@ -65,6 +65,15 @@ DEFINE_GUID(
     0x94, 0xc9, 0xf0, 0xd5, 0x25, 0xbb, 0xc1, 0x69
     );
 
+/* bfd4814c-9650-4de3-a536-1eedb9e9ba6a */
+DEFINE_GUID(
+    OVS_TUNNEL_FILTER_KEY,
+    0xbfd4814c,
+    0x9650,
+    0x4de3,
+    0xa5, 0x36, 0x1e, 0xed, 0xb9, 0xe9, 0xba, 0x6a
+    );
+
 /*
  * Callout driver global variables
  */
@@ -82,6 +91,7 @@ OvsTunnelAddFilter(PWSTR filterName,
                    USHORT remotePort,
                    FWP_DIRECTION direction,
                    UINT64 context,
+                   const GUID *filterKey,
                    const GUID *layerKey,
                    const GUID *calloutKey)
 {
@@ -93,6 +103,7 @@ OvsTunnelAddFilter(PWSTR filterName,
     UNREFERENCED_PARAMETER(remotePort);
     UNREFERENCED_PARAMETER(direction);
 
+    filter.filterKey = *filterKey;
     filter.layerKey = *layerKey;
     filter.displayData.name = (wchar_t*)filterName;
     filter.displayData.description = (wchar_t*)filterDesc;
@@ -130,6 +141,52 @@ OvsTunnelAddFilter(PWSTR filterName,
     return status;
 }
 
+NTSTATUS
+OvsTunnelRemoveFilter(const GUID *filterKey,
+                      const GUID *sublayerKey)
+{
+    NTSTATUS status = STATUS_SUCCESS;
+    BOOLEAN inTransaction = FALSE;
+
+    do {
+        status = FwpmTransactionBegin(gEngineHandle, 0);
+        if (!NT_SUCCESS(status)) {
+            break;
+        }
+
+        inTransaction = TRUE;
+
+        /*
+         * We have to delete the filter first since it references the
+         * sublayer. If we tried to delete the sublayer first, it would fail
+         * with FWP_ERR_IN_USE.
+         */
+        status = FwpmFilterDeleteByKey(gEngineHandle,
+                                       filterKey);
+        if (!NT_SUCCESS(status)) {
+            break;
+        }
+
+        status = FwpmSubLayerDeleteByKey(gEngineHandle,
+                                         sublayerKey);
+        if (!NT_SUCCESS(status)) {
+            break;
+        }
+
+        status = FwpmTransactionCommit(gEngineHandle);
+        if (!NT_SUCCESS(status)){
+            break;
+        }
+
+        inTransaction = FALSE;
+    } while (inTransaction);
+
+    if (inTransaction) {
+        FwpmTransactionAbort(gEngineHandle);
+    }
+    return status;
+}
+
 /*
  * --------------------------------------------------------------------------
  * This function registers callouts and filters that intercept UDP traffic at
@@ -155,7 +212,7 @@ OvsTunnelRegisterDatagramDataCallouts(const GUID *layerKey,
     sCallout.classifyFn = OvsTunnelClassify;
     sCallout.notifyFn = OvsTunnelNotify;
 #if FLOW_CONTEXT
-    /* Currnetly we don't associate a context with the flow */
+    /* Currently we don't associate a context with the flow */
     sCallout.flowDeleteFn = OvsTunnelFlowDelete;
     sCallout.flags = FWP_CALLOUT_FLAG_CONDITIONAL_ON_FLOW;
 #endif
@@ -190,6 +247,7 @@ OvsTunnelRegisterDatagramDataCallouts(const GUID *layerKey,
                                 configNewDestPort,
                                 FWP_DIRECTION_INBOUND,
                                 0,
+                                &OVS_TUNNEL_FILTER_KEY,
                                 layerKey,
                                 calloutKey);
 
@@ -288,12 +346,13 @@ OvsTunnelRegisterCallouts(VOID *deviceObject)
 VOID
 OvsTunnelUnregisterCallouts(VOID)
 {
+    OvsTunnelRemoveFilter(&OVS_TUNNEL_FILTER_KEY,
+                          &OVS_TUNNEL_SUBLAYER);
     FwpmEngineClose(gEngineHandle);
     gEngineHandle = NULL;
     FwpsCalloutUnregisterById(gCalloutIdV4);
 }
 
-
 VOID
 OvsTunnelFilterUninitialize(PDRIVER_OBJECT driverObject)
 {