Implement AliasOrigin processing in XCVM

xcm/xcm-builder/src/lib.rs

@@ -88,3 +88,6 @@ pub use universal_exports::{
 	ExporterFor, HaulBlob, HaulBlobError, HaulBlobExporter, NetworkExportTable,
 	SovereignPaidRemoteExporter, UnpaidLocalExporter, UnpaidRemoteExporter,
 };
+
+mod origin_aliases;
+pub use origin_aliases::{AliasCase, RemovePrefixAccountId32};

xcm/xcm-builder/src/origin_aliases.rs

@@ -0,0 +1,46 @@
+// 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, Get};
+use sp_std::marker::PhantomData;
+use xcm::latest::prelude::*;
+
+pub struct RemovePrefixAccountId32<Prefix>(PhantomData<Prefix>);
+impl<Prefix: Get<MultiLocation>> ContainsPair<MultiLocation, MultiLocation>
+	for RemovePrefixAccountId32<Prefix>
+{
+	fn contains(origin: &MultiLocation, target: &MultiLocation) -> bool {
+		if let Ok(appended) = (*target).clone().prepended_with(Prefix::get()) {
+			if appended == *origin {
+				match appended.last() {
+					Some(AccountId32 { .. }) => return true,
+					_ => return false,
+				}
+			}
+		}
+		false
+	}
+}
+
+pub struct AliasCase<T>(PhantomData<T>);
+impl<T: Get<(MultiLocation, MultiLocation)>> ContainsPair<MultiLocation, MultiLocation>
+	for AliasCase<T>
+{
+	fn contains(origin: &MultiLocation, target: &MultiLocation) -> bool {
+		let (o, t) = T::get();
+		&o == origin && &t == target
+	}
+}

xcm/xcm-builder/src/tests/aliases.rs

@@ -0,0 +1,71 @@
+// 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 super::*;
+
+#[test]
+fn alias_sibling_account_should_work() {
+	// Wrong parachain
+	assert!(!RemovePrefixAccountId32::<AliasSiblingPrefix>::contains(
+		&(Parent, Parachain(2), AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [0; 32] }).into()
+	));
+
+	// Accounts Differ
+	assert!(!RemovePrefixAccountId32::<AliasSiblingPrefix>::contains(
+		&(Parent, Parachain(1), AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [1; 32] }).into()
+	));
+
+	assert!(RemovePrefixAccountId32::<AliasSiblingPrefix>::contains(
+		&(Parent, Parachain(1), AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [0; 32] }).into()
+	));
+}
+
+#[test]
+fn alias_child_account_should_work() {
+	// Wrong parachain
+	assert!(!RemovePrefixAccountId32::<AliasChildPrefix>::contains(
+		&(Parachain(2), AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [0; 32] }).into()
+	));
+
+	// Accounts Differ
+	assert!(!RemovePrefixAccountId32::<AliasChildPrefix>::contains(
+		&(Parachain(1), AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [1; 32] }).into()
+	));
+
+	assert!(RemovePrefixAccountId32::<AliasChildPrefix>::contains(
+		&(Parachain(1), AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [0; 32] }).into()
+	));
+}
+
+#[test]
+fn alias_parent_account_should_work() {
+	// Accounts Differ
+	assert!(!RemovePrefixAccountId32::<AliasParentPrefix>::contains(
+		&(Parent, AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [1; 32] }).into()
+	));
+
+	assert!(RemovePrefixAccountId32::<AliasParentPrefix>::contains(
+		&(Parent, AccountId32 { network: None, id: [0; 32] }).into(),
+		&(AccountId32 { network: None, id: [0; 32] }).into()
+	));
+}

xcm/xcm-builder/src/tests/mock.rs

@@ -16,7 +16,9 @@
 
 use crate::{
 	barriers::{AllowSubscriptionsFrom, RespectSuspension},
+	origin_aliases::{AliasChildAccountId32, AliasParentAccountId32},
 	test_utils::*,
+	AliasSiblingAccountId32,
 };
 pub use crate::{
 	AllowExplicitUnpaidExecutionFrom, AllowKnownQueryResponses, AllowTopLevelPaidExecutionFrom,
@@ -30,7 +32,7 @@ pub use frame_support::{
 	},
 	ensure, parameter_types,
 	sp_runtime::DispatchErrorWithPostInfo,
-	traits::{Contains, Get, IsInVec},
+	traits::{ConstU32, Contains, Get, IsInVec},
 };
 pub use parity_scale_codec::{Decode, Encode};
 pub use sp_io::hashing::blake2_256;
@@ -642,6 +644,14 @@ impl AssetExchange for TestAssetExchange {
 	}
 }
 
+parameter_types! {
+	pub static AliasSiblingPrefix: MultiLocation = (Parent, Parachain(1)).into();
+	pub static AliasChildPrefix: MultiLocation = (Parachain(1)).into();
+	pub static AliasParentPrefix: MultiLocation = (Parent).into();
+}
+
+pub type TestAliases = ();
+
 pub struct TestConfig;
 impl Config for TestConfig {
 	type RuntimeCall = TestCall;
@@ -667,6 +677,7 @@ impl Config for TestConfig {
 	type MessageExporter = TestMessageExporter;
 	type CallDispatcher = TestCall;
 	type SafeCallFilter = Everything;
+	type Aliasers = TestAliases;
 }
 
 pub fn fungible_multi_asset(location: MultiLocation, amount: u128) -> MultiAsset {

xcm/xcm-builder/src/tests/mod.rs

@@ -26,6 +26,7 @@ use xcm_executor::{traits::prelude::*, Config, XcmExecutor};
 mod mock;
 use mock::*;
 
+mod aliases;
 mod assets;
 mod barriers;
 mod basic;

xcm/xcm-builder/tests/mock/mod.rs

@@ -203,6 +203,7 @@ impl xcm_executor::Config for XcmConfig {
 	type UniversalAliases = Nothing;
 	type CallDispatcher = RuntimeCall;
 	type SafeCallFilter = Everything;
+	type Aliasers = ();
 }
 
 pub type LocalOriginToLocation = SignedToAccountId32<RuntimeOrigin, AccountId, KusamaNetwork>;

xcm/xcm-executor/src/config.rs

@@ -45,6 +45,10 @@ pub trait Config {
 	/// Combinations of (Asset, Location) pairs which we trust as teleporters.
 	type IsTeleporter: ContainsPair<MultiAsset, MultiLocation>;
 
+	/// A list of (Origin, Target) pairs allowing a given Origin to be substituted with its
+	/// corresponding Target pair.
+	type Aliasers: ContainsPair<MultiLocation, MultiLocation>;
+
 	/// This chain's Universal Location.
 	type UniversalLocation: Get<InteriorMultiLocation>;
 

xcm/xcm-executor/src/lib.rs

@@ -909,7 +909,15 @@ impl<Config: config::Config> XcmExecutor<Config> {
 				self.context.topic = None;
 				Ok(())
 			},
-			AliasOrigin(_) => Err(XcmError::NoPermission),
+			AliasOrigin(target) => {
+				let origin = self.origin_ref().ok_or(XcmError::BadOrigin)?;
+				if Config::Aliasers::contains(origin, &target) {
+					self.context.origin = Some(target);
+					Ok(())
+				} else {
+					Err(XcmError::NoPermission)
+				}
+			},
 			UnpaidExecution { check_origin, .. } => {
 				ensure!(
 					check_origin.is_none() || self.context.origin == check_origin,