pallet-xcm: filter assets teleports based on XcmExecutor configuration

Add AssetTransferFilter trait for configuring transfer types.
Implement it for XcmExecutor based on existing executor teleports and
reserves configuration.
Filter assets on pallet-xcm::limited_teleport_assets() based on above.

cumulus/parachains/runtimes/assets/asset-hub-kusama/tests/tests.rs

@@ -519,12 +519,6 @@ asset_test_utils::include_teleports_for_native_asset_works!(
 			_ => None,
 		}
 	}),
-	Box::new(|runtime_event_encoded: Vec<u8>| {
-		match RuntimeEvent::decode(&mut &runtime_event_encoded[..]) {
-			Ok(RuntimeEvent::XcmpQueue(event)) => Some(event),
-			_ => None,
-		}
-	}),
 	1000
 );
 

cumulus/parachains/runtimes/assets/asset-hub-polkadot/tests/tests.rs

@@ -532,12 +532,6 @@ asset_test_utils::include_teleports_for_native_asset_works!(
 			_ => None,
 		}
 	}),
-	Box::new(|runtime_event_encoded: Vec<u8>| {
-		match RuntimeEvent::decode(&mut &runtime_event_encoded[..]) {
-			Ok(RuntimeEvent::XcmpQueue(event)) => Some(event),
-			_ => None,
-		}
-	}),
 	1000
 );
 

cumulus/parachains/runtimes/assets/asset-hub-westend/tests/tests.rs

@@ -526,12 +526,6 @@ asset_test_utils::include_teleports_for_native_asset_works!(
 			_ => None,
 		}
 	}),
-	Box::new(|runtime_event_encoded: Vec<u8>| {
-		match RuntimeEvent::decode(&mut &runtime_event_encoded[..]) {
-			Ok(RuntimeEvent::XcmpQueue(event)) => Some(event),
-			_ => None,
-		}
-	}),
 	1000
 );
 

cumulus/parachains/runtimes/assets/test-utils/src/test_cases.rs

@@ -42,8 +42,8 @@ type RuntimeHelper<Runtime, AllPalletsWithoutSystem = ()> =
 // Re-export test_case from `parachains-runtimes-test-utils`
 pub use parachains_runtimes_test_utils::test_cases::change_storage_constant_by_governance_works;
 
-/// Test-case makes sure that `Runtime` can receive native asset from relay chain
-/// and can teleport it back and to the other parachains
+/// Test-case makes sure that `Runtime` can receive native asset from relay chain and can teleport
+/// it back
 pub fn teleports_for_native_asset_works<
 	Runtime,
 	AllPalletsWithoutSystem,
@@ -56,9 +56,6 @@ pub fn teleports_for_native_asset_works<
 	existential_deposit: BalanceOf<Runtime>,
 	target_account: AccountIdOf<Runtime>,
 	unwrap_pallet_xcm_event: Box<dyn Fn(Vec<u8>) -> Option<pallet_xcm::Event<Runtime>>>,
-	unwrap_xcmp_queue_event: Box<
-		dyn Fn(Vec<u8>) -> Option<cumulus_pallet_xcmp_queue::Event<Runtime>>,
-	>,
 	runtime_para_id: u32,
 ) where
 	Runtime: frame_system::Config
@@ -204,7 +201,8 @@ pub fn teleports_for_native_asset_works<
 				);
 			}
 
-			// 3. try to teleport asset away to other parachain (1234)
+			// 3. try to teleport assets away to other parachain (1234): should not work as we don't
+			//    trust `IsTeleporter` for `(relay-native-asset, para(1234))` pair
 			{
 				let other_para_id = 1234;
 				let dest = MultiLocation::new(1, X1(Parachain(other_para_id)));
@@ -217,41 +215,38 @@ pub fn teleports_for_native_asset_works<
 
 				let target_account_balance_before_teleport =
 					<pallet_balances::Pallet<Runtime>>::free_balance(&target_account);
+
 				let native_asset_to_teleport_away = native_asset_amount_unit * 3.into();
 				assert!(
 					native_asset_to_teleport_away <
 						target_account_balance_before_teleport - existential_deposit
 				);
-
-				assert_ok!(RuntimeHelper::<Runtime>::do_teleport_assets::<HrmpChannelOpener>(
-					RuntimeHelper::<Runtime>::origin_of(target_account.clone()),
-					dest,
-					dest_beneficiary,
-					(native_asset_id, native_asset_to_teleport_away.into()),
-					Some((runtime_para_id, other_para_id)),
-					included_head,
-					&alice,
-				));
+				assert_eq!(
+					RuntimeHelper::<Runtime>::do_teleport_assets::<HrmpChannelOpener>(
+						RuntimeHelper::<Runtime>::origin_of(target_account.clone()),
+						dest,
+						dest_beneficiary,
+						(native_asset_id, native_asset_to_teleport_away.into()),
+						Some((runtime_para_id, other_para_id)),
+						included_head,
+						&alice,
+					),
+					Err(DispatchError::Module(sp_runtime::ModuleError {
+						index: 31,
+						error: [2, 0, 0, 0,],
+						message: Some("Filtered",),
+					},),)
+				);
 
 				// check balances
 				assert_eq!(
 					<pallet_balances::Pallet<Runtime>>::free_balance(&target_account),
-					target_account_balance_before_teleport - native_asset_to_teleport_away
+					target_account_balance_before_teleport
 				);
 				assert_eq!(
 					<pallet_balances::Pallet<Runtime>>::free_balance(&CheckingAccount::get()),
 					0.into()
 				);
-
-				// check events
-				RuntimeHelper::<Runtime>::assert_pallet_xcm_event_outcome(
-					&unwrap_pallet_xcm_event,
-					|outcome| {
-						assert_ok!(outcome.ensure_complete());
-					},
-				);
-				assert!(RuntimeHelper::<Runtime>::xcmp_queue_message_sent(unwrap_xcmp_queue_event)
-					.is_some());
 			}
 		})
 }
@@ -268,7 +263,6 @@ macro_rules! include_teleports_for_native_asset_works(
 		$collator_session_key:expr,
 		$existential_deposit:expr,
 		$unwrap_pallet_xcm_event:expr,
-		$unwrap_xcmp_queue_event:expr,
 		$runtime_para_id:expr
 	) => {
 		#[test]
@@ -288,15 +282,14 @@ macro_rules! include_teleports_for_native_asset_works(
 				$existential_deposit,
 				target_account,
 				$unwrap_pallet_xcm_event,
-				$unwrap_xcmp_queue_event,
 				$runtime_para_id
 			)
 		}
 	}
 );
 
-/// Test-case makes sure that `Runtime` can receive teleported assets from sibling parachain relay
-/// chain
+/// Test-case makes sure that `Runtime` can receive teleported assets from sibling parachain, and
+/// can teleport it back
 pub fn teleports_for_foreign_assets_works<
 	Runtime,
 	AllPalletsWithoutSystem,
@@ -442,7 +435,7 @@ pub fn teleports_for_foreign_assets_works<
 			>(foreign_asset_id_multilocation, 0, 0);
 			assert!(teleported_foreign_asset_amount > asset_minimum_asset_balance);
 
-			// 1. process received teleported assets from relaychain
+			// 1. process received teleported assets from sibling parachain (foreign_para_id)
 			let xcm = Xcm(vec![
 				// BuyExecution with relaychain native token
 				WithdrawAsset(buy_execution_fee.clone().into()),

cumulus/parachains/runtimes/bridge-hubs/bridge-hub-kusama/tests/tests.rs

@@ -47,11 +47,5 @@ bridge_hub_test_utils::test_cases::include_teleports_for_native_asset_works!(
 			_ => None,
 		}
 	}),
-	Box::new(|runtime_event_encoded: Vec<u8>| {
-		match RuntimeEvent::decode(&mut &runtime_event_encoded[..]) {
-			Ok(RuntimeEvent::XcmpQueue(event)) => Some(event),
-			_ => None,
-		}
-	}),
 	1002
 );

cumulus/parachains/runtimes/bridge-hubs/bridge-hub-polkadot/tests/tests.rs

@@ -47,11 +47,5 @@ bridge_hub_test_utils::test_cases::include_teleports_for_native_asset_works!(
 			_ => None,
 		}
 	}),
-	Box::new(|runtime_event_encoded: Vec<u8>| {
-		match RuntimeEvent::decode(&mut &runtime_event_encoded[..]) {
-			Ok(RuntimeEvent::XcmpQueue(event)) => Some(event),
-			_ => None,
-		}
-	}),
 	1002
 );

cumulus/parachains/runtimes/bridge-hubs/bridge-hub-rococo/tests/tests.rs

@@ -118,12 +118,6 @@ mod bridge_hub_rococo_tests {
 				_ => None,
 			}
 		}),
-		Box::new(|runtime_event_encoded: Vec<u8>| {
-			match RuntimeEvent::decode(&mut &runtime_event_encoded[..]) {
-				Ok(RuntimeEvent::XcmpQueue(event)) => Some(event),
-				_ => None,
-			}
-		}),
 		bp_bridge_hub_rococo::BRIDGE_HUB_ROCOCO_PARACHAIN_ID
 	);
 
@@ -297,12 +291,6 @@ mod bridge_hub_wococo_tests {
 				_ => None,
 			}
 		}),
-		Box::new(|runtime_event_encoded: Vec<u8>| {
-			match RuntimeEvent::decode(&mut &runtime_event_encoded[..]) {
-				Ok(RuntimeEvent::XcmpQueue(event)) => Some(event),
-				_ => None,
-			}
-		}),
 		bp_bridge_hub_wococo::BRIDGE_HUB_WOCOCO_PARACHAIN_ID
 	);
 

polkadot/xcm/pallet-xcm/src/lib.rs

@@ -41,7 +41,7 @@ use sp_runtime::{
 };
 use sp_std::{boxed::Box, marker::PhantomData, prelude::*, result::Result, vec};
 use xcm::{latest::QueryResponseInfo, prelude::*};
-use xcm_executor::traits::{ConvertOrigin, Properties};
+use xcm_executor::traits::{AssetTransferFilter, ConvertOrigin, Properties};
 
 use frame_support::{
 	dispatch::GetDispatchInfo, pallet_prelude::*, traits::WithdrawReasons, PalletId,
@@ -206,7 +206,7 @@ pub mod pallet {
 		type XcmExecuteFilter: Contains<(MultiLocation, Xcm<<Self as Config>::RuntimeCall>)>;
 
 		/// Something to execute an XCM message.
-		type XcmExecutor: ExecuteXcm<<Self as Config>::RuntimeCall>;
+		type XcmExecutor: ExecuteXcm<<Self as Config>::RuntimeCall> + AssetTransferFilter;
 
 		/// Our XCM filter which messages to be teleported using the dedicated extrinsic must pass.
 		type XcmTeleportFilter: Contains<(MultiLocation, Vec<MultiAsset>)>;
@@ -1212,6 +1212,18 @@ impl<T: Config> Pallet<T> {
 		let value = (origin_location, assets.into_inner());
 		ensure!(T::XcmReserveTransferFilter::contains(&value), Error::<T>::Filtered);
 		let (origin_location, assets) = value;
+		// Don't allow inclusion of teleportable assets in this reserve-based-transfer (other than
+		// fee asset).
+		for (idx, asset) in assets.iter().enumerate() {
+			ensure!(
+				idx == fee_asset_item as usize ||
+					!<T::XcmExecutor as AssetTransferFilter>::IsTeleporter::contains(
+						asset, &dest
+					),
+				Error::<T>::Filtered
+			);
+		}
+
 		let context = T::UniversalLocation::get();
 		let fees = assets
 			.get(fee_asset_item as usize)
@@ -1256,6 +1268,12 @@ impl<T: Config> Pallet<T> {
 		let value = (origin_location, assets.into_inner());
 		ensure!(T::XcmTeleportFilter::contains(&value), Error::<T>::Filtered);
 		let (origin_location, assets) = value;
+		for asset in assets.iter() {
+			ensure!(
+				<T::XcmExecutor as AssetTransferFilter>::IsTeleporter::contains(asset, &dest),
+				Error::<T>::Filtered
+			);
+		}
 		let context = T::UniversalLocation::get();
 		let fees = assets
 			.get(fee_asset_item as usize)

polkadot/xcm/xcm-executor/src/lib.rs

@@ -38,6 +38,7 @@ use traits::{
 mod assets;
 pub use assets::Assets;
 mod config;
+use crate::traits::AssetTransferFilter;
 pub use config::Config;
 
 /// A struct to specify how fees are being paid.
@@ -254,6 +255,11 @@ impl<Config: config::Config> ExecuteXcm<Config::RuntimeCall> for XcmExecutor<Con
 	}
 }
 
+impl<Config: config::Config> AssetTransferFilter for XcmExecutor<Config> {
+	type IsReserve = Config::IsReserve;
+	type IsTeleporter = Config::IsTeleporter;
+}
+
 #[derive(Debug)]
 pub struct ExecutorError {
 	pub index: u32,

polkadot/xcm/xcm-executor/src/traits/asset_transfer.rs

@@ -0,0 +1,29 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use frame_support::traits::ContainsPair;
+use xcm::prelude::*;
+
+/// A trait for identifying asset transfer type.
+pub trait AssetTransferFilter {
+	/// Combinations of (Asset, Location) pairs which we trust as reserves. Meaning
+	/// reserve-based-transfers are to be used for assets matching this filter.
+	type IsReserve: ContainsPair<MultiAsset, MultiLocation>;
+
+	/// Combinations of (Asset, Location) pairs which we trust as teleporters. Meaning teleports are
+	/// to be used for assets matching this filter.
+	type IsTeleporter: ContainsPair<MultiAsset, MultiLocation>;
+}

polkadot/xcm/xcm-executor/src/traits/mod.rs

@@ -20,10 +20,12 @@ mod conversion;
 pub use conversion::{CallDispatcher, ConvertLocation, ConvertOrigin, WithOriginFilter};
 mod drop_assets;
 pub use drop_assets::{ClaimAssets, DropAssets};
-mod asset_lock;
-pub use asset_lock::{AssetLock, Enact, LockError};
 mod asset_exchange;
 pub use asset_exchange::AssetExchange;
+mod asset_lock;
+pub use asset_lock::{AssetLock, Enact, LockError};
+mod asset_transfer;
+pub use asset_transfer::AssetTransferFilter;
 mod export;
 pub use export::{export_xcm, validate_export, ExportXcm};
 mod fee_manager;