Companion for paritytech/cumulus#1169

runtime/common/src/lib.rs

@@ -18,6 +18,8 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
+pub mod xcm_config;
+
 // --- core ---
 use core::marker::PhantomData;
 // --- paritytech ---

runtime/common/src/xcm_config.rs

@@ -0,0 +1,67 @@
+use core::marker::PhantomData;
+use frame_support::{log, weights::Weight};
+use xcm::latest::prelude::*;
+use xcm_executor::traits::ShouldExecute;
+
+//TODO: move DenyThenTry to polkadot's xcm module.
+/// Deny executing the XCM if it matches any of the Deny filter regardless of anything else.
+/// If it passes the Deny, and matches one of the Allow cases then it is let through.
+pub struct DenyThenTry<Deny, Allow>(PhantomData<Deny>, PhantomData<Allow>)
+where
+	Deny: ShouldExecute,
+	Allow: ShouldExecute;
+
+impl<Deny, Allow> ShouldExecute for DenyThenTry<Deny, Allow>
+where
+	Deny: ShouldExecute,
+	Allow: ShouldExecute,
+{
+	fn should_execute<Call>(
+		origin: &MultiLocation,
+		message: &mut Xcm<Call>,
+		max_weight: Weight,
+		weight_credit: &mut Weight,
+	) -> Result<(), ()> {
+		Deny::should_execute(origin, message, max_weight, weight_credit)?;
+		Allow::should_execute(origin, message, max_weight, weight_credit)
+	}
+}
+
+// See issue #5233
+pub struct DenyReserveTransferToRelayChain;
+impl ShouldExecute for DenyReserveTransferToRelayChain {
+	fn should_execute<Call>(
+		origin: &MultiLocation,
+		message: &mut Xcm<Call>,
+		_max_weight: Weight,
+		_weight_credit: &mut Weight,
+	) -> Result<(), ()> {
+		if message.0.iter().any(|inst| {
+			matches!(
+				inst,
+				InitiateReserveWithdraw {
+					reserve: MultiLocation { parents: 1, interior: Here },
+					..
+				} | DepositReserveAsset { dest: MultiLocation { parents: 1, interior: Here }, .. } |
+					TransferReserveAsset {
+						dest: MultiLocation { parents: 1, interior: Here },
+						..
+					}
+			)
+		}) {
+			return Err(()) // Deny
+		}
+
+		// allow reserve transfers to arrive from relay chain
+		if matches!(origin, MultiLocation { parents: 1, interior: Here }) &&
+			message.0.iter().any(|inst| matches!(inst, ReserveAssetDeposited { .. }))
+		{
+			log::info!(
+				target: "runtime::xcm-barier",
+				"Unexpected Reserve Assets Deposited on the relay chain",
+			);
+		}
+		// Permit everything else
+		Ok(())
+	}
+}

runtime/crab-parachain/src/pallets/polkadot_xcm.rs

@@ -13,6 +13,7 @@ use xcm_builder::*;
 use xcm_executor::{Config as XcmCExecutorConfig, XcmExecutor};
 // --- darwinia-network ---
 use crate::*;
+use dc_common_runtime::xcm_config::{DenyReserveTransferToRelayChain, DenyThenTry};
 
 /// Converts a local signed origin into an XCM multilocation.
 /// Forms the basis for local origins sending/executing XCMs.
@@ -41,16 +42,19 @@ pub type XcmRouter = (
 	XcmpQueue,
 );
 
-pub type Barrier = (
-	TakeWeightCredit,
-	AllowTopLevelPaidExecutionFrom<Everything>,
-	// Parent and its plurality get free execution
-	AllowUnpaidExecutionFrom<ParentOrParentsExecutivePlurality>,
-	// Expected responses are OK.
-	AllowKnownQueryResponses<PolkadotXcm>,
-	// Subscriptions for version tracking are OK.
-	AllowSubscriptionsFrom<ParentOrSiblings>,
-);
+pub type Barrier = DenyThenTry<
+	DenyReserveTransferToRelayChain,
+	(
+		TakeWeightCredit,
+		AllowTopLevelPaidExecutionFrom<Everything>,
+		// Parent and its exec plurality get free execution
+		AllowUnpaidExecutionFrom<ParentOrParentsExecutivePlurality>,
+		// Expected responses are OK.
+		AllowKnownQueryResponses<PolkadotXcm>,
+		// Subscriptions for version tracking are OK.
+		AllowSubscriptionsFrom<ParentOrSiblings>,
+	),
+>;
 
 /// Type for specifying how a `MultiLocation` can be converted into an `AccountId`. This is used
 /// when determining ownership of accounts for asset transacting and when attempting to use XCM

runtime/darwinia-parachain/src/pallets/polkadot_xcm.rs

@@ -13,6 +13,7 @@ use xcm_builder::*;
 use xcm_executor::{Config as XcmCExecutorConfig, XcmExecutor};
 // --- darwinia-network ---
 use crate::*;
+use dc_common_runtime::xcm_config::{DenyReserveTransferToRelayChain, DenyThenTry};
 
 /// Converts a local signed origin into an XCM multilocation.
 /// Forms the basis for local origins sending/executing XCMs.
@@ -41,16 +42,19 @@ pub type XcmRouter = (
 	XcmpQueue,
 );
 
-pub type Barrier = (
-	TakeWeightCredit,
-	AllowTopLevelPaidExecutionFrom<Everything>,
-	// Parent and its plurality get free execution
-	AllowUnpaidExecutionFrom<ParentOrParentsExecutivePlurality>,
-	// Expected responses are OK.
-	AllowKnownQueryResponses<PolkadotXcm>,
-	// Subscriptions for version tracking are OK.
-	AllowSubscriptionsFrom<ParentOrSiblings>,
-);
+pub type Barrier = DenyThenTry<
+	DenyReserveTransferToRelayChain,
+	(
+		TakeWeightCredit,
+		AllowTopLevelPaidExecutionFrom<Everything>,
+		// Parent and its exec plurality get free execution
+		AllowUnpaidExecutionFrom<ParentOrParentsExecutivePlurality>,
+		// Expected responses are OK.
+		AllowKnownQueryResponses<PolkadotXcm>,
+		// Subscriptions for version tracking are OK.
+		AllowSubscriptionsFrom<ParentOrSiblings>,
+	),
+>;
 
 /// Type for specifying how a `MultiLocation` can be converted into an `AccountId`. This is used
 /// when determining ownership of accounts for asset transacting and when attempting to use XCM

runtime/pangolin-parachain/src/pallets/polkadot_xcm.rs

@@ -13,6 +13,7 @@ use xcm_builder::*;
 use xcm_executor::{Config as XcmCExecutorConfig, XcmExecutor};
 // --- darwinia-network ---
 use crate::*;
+use dc_common_runtime::xcm_config::{DenyReserveTransferToRelayChain, DenyThenTry};
 
 /// Converts a local signed origin into an XCM multilocation.
 /// Forms the basis for local origins sending/executing XCMs.
@@ -41,16 +42,19 @@ pub type XcmRouter = (
 	XcmpQueue,
 );
 
-pub type Barrier = (
-	TakeWeightCredit,
-	AllowTopLevelPaidExecutionFrom<Everything>,
-	// Parent and its plurality get free execution
-	AllowUnpaidExecutionFrom<ParentOrParentsExecutivePlurality>,
-	// Expected responses are OK.
-	AllowKnownQueryResponses<PolkadotXcm>,
-	// Subscriptions for version tracking are OK.
-	AllowSubscriptionsFrom<ParentOrSiblings>,
-);
+pub type Barrier = DenyThenTry<
+	DenyReserveTransferToRelayChain,
+	(
+		TakeWeightCredit,
+		AllowTopLevelPaidExecutionFrom<Everything>,
+		// Parent and its exec plurality get free execution
+		AllowUnpaidExecutionFrom<ParentOrParentsExecutivePlurality>,
+		// Expected responses are OK.
+		AllowKnownQueryResponses<PolkadotXcm>,
+		// Subscriptions for version tracking are OK.
+		AllowSubscriptionsFrom<ParentOrSiblings>,
+	),
+>;
 
 /// Type for specifying how a `MultiLocation` can be converted into an `AccountId`. This is used
 /// when determining ownership of accounts for asset transacting and when attempting to use XCM