[Feature] Limit collectives teleports to DOT

pallets/xcm/Cargo.toml

@@ -8,6 +8,7 @@ version = "0.1.0"
 codec = { package = "parity-scale-codec", version = "3.0.0", default-features = false, features = ["derive"] }
 scale-info = { version = "2.1.1", default-features = false, features = ["derive"] }
 serde = { version = "1.0.144", optional = true, features = ["derive"] }
+log = "0.4.17"
 
 sp-std = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 sp-io = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
@@ -16,6 +17,7 @@ frame-support = { git = "https://github.com/paritytech/substrate", default-featu
 frame-system = { git = "https://github.com/paritytech/substrate", default-features = false, branch = "master" }
 
 xcm = { git = "https://github.com/paritytech/polkadot", default-features = false, branch = "master" }
+xcm-executor = { git = "https://github.com/paritytech/polkadot", default-features = false, branch = "master" }
 
 cumulus-primitives-core = { path = "../../primitives/core", default-features = false }
 

pallets/xcm/src/lib.rs

@@ -24,15 +24,16 @@ use codec::{Decode, DecodeLimit, Encode};
 use cumulus_primitives_core::{
 	relay_chain::BlockNumber as RelayBlockNumber, DmpMessageHandler, ParaId,
 };
-use frame_support::dispatch::Weight;
+use frame_support::{dispatch::Weight, traits::Get};
 pub use pallet::*;
 use scale_info::TypeInfo;
 use sp_runtime::{traits::BadOrigin, RuntimeDebug};
-use sp_std::{convert::TryFrom, prelude::*};
+use sp_std::{convert::TryFrom, marker::PhantomData, prelude::*};
 use xcm::{
-	latest::{ExecuteXcm, Outcome, Parent, Xcm},
+	latest::{AssetId::Concrete, ExecuteXcm, MultiAsset, MultiLocation, Outcome, Parent, Xcm},
 	VersionedXcm, MAX_XCM_DECODE_DEPTH,
 };
+use xcm_executor::traits::FilterAssetLocation;
 
 #[frame_support::pallet]
 pub mod pallet {
@@ -190,3 +191,14 @@ where
 		_ => Err(BadOrigin),
 	}
 }
+
+/// Accepts an asset if it is a native asset of a particular type.
+pub struct ConcreteNativeAsset<AssetId>(PhantomData<AssetId>);
+impl<AssetId: Get<MultiLocation>> FilterAssetLocation for ConcreteNativeAsset<AssetId> {
+	fn filter_asset_location(asset: &MultiAsset, origin: &MultiLocation) -> bool {
+		log::trace!(target: "xcm::filter_asset_location",
+			"ConcreteNativeAsset asset: {:?}, origin: {:?}, id: {:?}",
+			asset, origin, AssetId::get());
+		matches!(asset.id, Concrete(ref id) if id == origin && origin == &AssetId::get())
+	}
+}

parachains/runtimes/collectives/collectives-polkadot/src/xcm_config.rs

@@ -32,8 +32,8 @@ use xcm::latest::prelude::*;
 use xcm_builder::{
 	AccountId32Aliases, AllowKnownQueryResponses, AllowSubscriptionsFrom,
 	AllowTopLevelPaidExecutionFrom, AllowUnpaidExecutionFrom, CurrencyAdapter, EnsureXcmOrigin,
-	FixedWeightBounds, IsConcrete, LocationInverter, NativeAsset, ParentAsSuperuser,
-	ParentIsPreset, RelayChainAsNative, SiblingParachainAsNative, SiblingParachainConvertsVia,
+	FixedWeightBounds, IsConcrete, LocationInverter, ParentAsSuperuser, ParentIsPreset,
+	RelayChainAsNative, SiblingParachainAsNative, SiblingParachainConvertsVia,
 	SignedAccountId32AsNative, SignedToAccountId32, SovereignSignedViaLocation, TakeWeightCredit,
 	UsingComponents,
 };
@@ -140,7 +140,7 @@ impl xcm_executor::Config for XcmConfig {
 	// Collectives does not recognize a reserve location for any asset. Users must teleport DOT
 	// where allowed (e.g. with the Relay Chain).
 	type IsReserve = ();
-	type IsTeleporter = NativeAsset; // <- should be enough to allow teleportation of DOT
+	type IsTeleporter = cumulus_pallet_xcm::ConcreteNativeAsset<DotLocation>; // <- should be enough to allow teleportation of DOT
 	type LocationInverter = LocationInverter<Ancestry>;
 	type Barrier = Barrier;
 	type Weigher = FixedWeightBounds<UnitWeightCost, Call, MaxInstructions>;