Delay initializing RPC binding handle (#2679)

Signed-off-by: Alan Jowett <alan.jowett@microsoft.com>
Co-authored-by: Alan Jowett <alan.jowett@microsoft.com>

ebpfapi/rpc_client.cpp

@@ -14,6 +14,7 @@
 #include <windows.h>
 #include <ctype.h>
 #include <iostream>
+#include <mutex>
 #include <sddl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -23,6 +24,11 @@
 static const wchar_t* _protocol_sequence = L"ncalrpc";
 static bool _binding_initialized = false;
 
+static std::mutex _rpc_binding_handle_mutex;
+
+static RPC_STATUS
+_initialize_rpc_binding();
+
 _Must_inspect_result_ ebpf_result_t
 ebpf_rpc_load_program(
     _In_ const ebpf_program_load_info* info,
@@ -31,6 +37,10 @@ ebpf_rpc_load_program(
 {
     ebpf_result_t result;
 
+    if (_initialize_rpc_binding() != RPC_S_OK) {
+        return EBPF_NO_MEMORY;
+    }
+
     RpcTryExcept
     {
         result = ebpf_client_verify_and_load_program(
@@ -50,9 +60,22 @@ ebpf_rpc_load_program(
         return result;
 }
 
-RPC_STATUS
-initialize_rpc_binding()
+/**
+ * @brief Initialize the RPC binding handle. This is expensive and should be
+ * done once when required. This function is idempotent and thread safe.
+ *
+ * @retval RPC_S_OK The binding handle was initialized successfully.
+ * @retval RPC_S_* The binding handle could not be initialized.
+ */
+static RPC_STATUS
+_initialize_rpc_binding()
 {
+    std::unique_lock lock(_rpc_binding_handle_mutex);
+
+    if (_binding_initialized) {
+        return RPC_S_OK;
+    }
+
     RPC_WSTR string_binding = nullptr;
     RPC_SECURITY_QOS_V5 rpc_security_qos{
         RPC_C_SECURITY_QOS_VERSION_5,
@@ -121,10 +144,13 @@ Exit:
 RPC_STATUS
 clean_up_rpc_binding()
 {
+    std::unique_lock lock(_rpc_binding_handle_mutex);
     if (!_binding_initialized) {
         return RPC_S_OK;
     }
-    return RpcBindingFree(&ebpf_service_interface_handle);
+    RPC_STATUS status = RpcBindingFree(&ebpf_service_interface_handle);
+    _binding_initialized = false;
+    return status;
 }
 
 // The _In_ on size is necessary to avoid inconsistent annotation warnings.

libs/api/ebpf_api.cpp

@@ -204,16 +204,6 @@ ebpf_api_initiate() noexcept
     // it will be re-attempted before an IOCTL call is made.
     (void)initialize_device_handle();
 
-#if !defined(CONFIG_BPF_JIT_DISABLED) || !defined(CONFIG_BPF_INTERPRETER_DISABLED)
-    RPC_STATUS status = initialize_rpc_binding();
-
-    if (status != RPC_S_OK) {
-        clean_up_device_handle();
-        clean_up_rpc_binding();
-        EBPF_RETURN_RESULT(win32_error_code_to_ebpf_result(status));
-    }
-#endif
-
     // Load provider data from ebpf store. This is best effort
     // as there may be no data present in the store.
     (void)load_ebpf_provider_data();

libs/api/rpc_client.h

@@ -7,9 +7,6 @@
 
 #include <rpc.h>
 
-RPC_STATUS
-initialize_rpc_binding(void);
-
 RPC_STATUS
 clean_up_rpc_binding(void);
 

libs/thunk/mock/mock.cpp

@@ -189,9 +189,6 @@ _stop_service(SC_HANDLE service_handle)
 #if !defined(CONFIG_BPF_JIT_DISABLED) || !defined(CONFIG_BPF_INTERPRETER_DISABLED)
 // RPC related mock functions.
 
-RPC_STATUS
-initialize_rpc_binding() { return RPC_S_OK; }
-
 RPC_STATUS
 clean_up_rpc_binding() { return RPC_S_OK; }