Linux/macOS: surface post-sudo elevation errors

Separate sudo authentication success from elevated request execution state by acknowledging when the elevated core service starts successfully.

Once that channel is available, propagate later failures instead of showing repeated administrator password dialogs. Initialize the sudo dummy-password flag consistently on macOS, avoiding an uninitialized read of UseDummySudoPassword.

Register admin-password cleanup before elevation attempts so plaintext sudo credentials are erased on early-return and post-sudo failure paths.

References #1788.

src/Core/Unix/CoreService.cpp

@@ -110,8 +110,7 @@ namespace VeraCrypt
 	}
 #endif
 
-	template <class T>
-	unique_ptr <T> CoreService::GetResponse ()
+	unique_ptr <Serializable> CoreService::GetResponseObject ()
 	{
 		unique_ptr <Serializable> deserializedObject (Serializable::DeserializeNew (ServiceOutputStream));
 
@@ -119,6 +118,14 @@ namespace VeraCrypt
 		if (deserializedException)
 			deserializedException->Throw();
 
+		return deserializedObject;
+	}
+
+	template <class T>
+	unique_ptr <T> CoreService::GetResponse ()
+	{
+		unique_ptr <Serializable> deserializedObject (GetResponseObject());
+
 		if (dynamic_cast <T *> (deserializedObject.get()) == nullptr)
 			throw ParameterIncorrect (SRC_POS);
 
@@ -199,14 +206,21 @@ namespace VeraCrypt
 
 					if (!ElevatedPrivileges && request->ElevateUserPrivileges)
 					{
+						bool elevatedServiceStarted = false;
+
 						if (!ElevatedServiceAvailable)
 						{
 							finally_do_arg (string *, &request->AdminPassword, { StringConverter::Erase (*finally_arg); });
 
 							CoreService::StartElevated (*request);
 							ElevatedServiceAvailable = true;
+							elevatedServiceStarted = true;
 						}
 
+						// Report sudo/elevated-service success before executing the request.
+						if (elevatedServiceStarted)
+							ElevatedServiceStartedResponse().Serialize (outputStream);
+
 						request->Serialize (ServiceInputStream);
 						GetResponse <Serializable>()->Serialize (outputStream);
 						continue;
@@ -424,6 +438,7 @@ namespace VeraCrypt
 		request.UserEnvPATH = Core->GetUserEnvPATH();
 		request.UseDummySudoPassword = Core->GetUseDummySudoPassword();
 		request.AllowInsecureMount = Core->GetAllowInsecureMount();
+		finally_do_arg (string *, &request.AdminPassword, { StringConverter::Erase (*finally_arg); });
 
 		if (request.RequiresElevation())
 		{
@@ -482,12 +497,28 @@ namespace VeraCrypt
 				try
 				{
 					request.Serialize (ServiceInputStream);
-					unique_ptr <T> response (GetResponse <T>());
+
+					unique_ptr <Serializable> response (GetResponseObject());
+					if (dynamic_cast <ElevatedServiceStartedResponse *> (response.get()) != nullptr)
+					{
+						// The elevated channel is usable even if the forwarded request fails.
+						// Any later failure must be propagated as the real error rather than
+						// triggering another administrator-password prompt.
+						ElevatedServiceAvailable = true;
+						return GetResponse <T> ();
+					}
+
+					if (dynamic_cast <T *> (response.get()) == nullptr)
+						throw ParameterIncorrect (SRC_POS);
+
 					ElevatedServiceAvailable = true;
-					return response;
+					return unique_ptr <T> (dynamic_cast <T *> (response.release()));
 				}
 				catch (ElevationFailed &e)
 				{
+					if (ElevatedServiceAvailable)
+						throw;
+
 					if (!request.FastElevation)
 					{
 						ExceptionEventArgs args (e);
@@ -502,8 +533,6 @@ namespace VeraCrypt
 			}
 		}
 
-		finally_do_arg (string *, &request.AdminPassword, { StringConverter::Erase (*finally_arg); });
-
 		request.Serialize (ServiceInputStream);
 		return GetResponse <T>();
 	}