Make automatic storage deposits resistant against changing deposit pr…

…ices (#12083)

* Require `FixedPointOperand` for Balances

* Delay deposit calculation

* Make refunds pro rata of consumed storage

* Add storage migration

* Fix clippy

* Add liquidity checks

* Fixe delayed deposit limit enforcement

* Defer charges

* Import Vec

* Add try-runtime hooks for migration

* Fix warning

* Adapt to new OnRuntimeUpgrade trait

* Apply suggestions from code review

Co-authored-by: Sasha Gryaznov <hi@agryaznov.com>

* fmt

* Apply suggestions from code review

Co-authored-by: Sasha Gryaznov <hi@agryaznov.com>

* More suggestions from code review

Co-authored-by: Sasha Gryaznov <hi@agryaznov.com>

bin/node/runtime/src/lib.rs

@@ -1706,6 +1706,7 @@ pub type Executive = frame_executive::Executive<
 type Migrations = (
 	pallet_nomination_pools::migration::v2::MigrateToV2<Runtime>,
 	pallet_alliance::migration::Migration<Runtime>,
+	pallet_contracts::Migration<Runtime>,
 );
 
 /// MMR helper types.

frame/balances/src/lib.rs

@@ -185,7 +185,7 @@ use sp_runtime::{
 		AtLeast32BitUnsigned, Bounded, CheckedAdd, CheckedSub, MaybeSerializeDeserialize,
 		Saturating, StaticLookup, Zero,
 	},
-	ArithmeticError, DispatchError, RuntimeDebug,
+	ArithmeticError, DispatchError, FixedPointOperand, RuntimeDebug,
 };
 use sp_std::{cmp, fmt::Debug, mem, ops::BitOr, prelude::*, result};
 pub use weights::WeightInfo;
@@ -212,7 +212,8 @@ pub mod pallet {
 			+ MaybeSerializeDeserialize
 			+ Debug
 			+ MaxEncodedLen
-			+ TypeInfo;
+			+ TypeInfo
+			+ FixedPointOperand;
 
 		/// Handler for the unbalanced reduction when removing a dust account.
 		type DustRemoval: OnUnbalanced<NegativeImbalance<Self, I>>;

frame/contracts/fixtures/create_storage_and_call.wat

@@ -0,0 +1,55 @@
+;; This calls another contract as passed as its account id. It also creates some storage.
+(module
+	(import "seal0" "seal_input" (func $seal_input (param i32 i32)))
+	(import "seal0" "seal_set_storage" (func $seal_set_storage (param i32 i32 i32)))
+	(import "seal1" "seal_call" (func $seal_call (param i32 i32 i64 i32 i32 i32 i32 i32) (result i32)))
+	(import "env" "memory" (memory 1 1))
+
+	(func $assert (param i32)
+		(block $ok
+			(br_if $ok
+				(get_local 0)
+			)
+			(unreachable)
+		)
+	)
+
+    (func (export "deploy"))
+
+    (func (export "call")
+    	;; store length of input buffer
+        (i32.store (i32.const 0) (i32.const 512))
+
+        ;; copy input at address 4
+        (call $seal_input (i32.const 4) (i32.const 0))
+
+       	;; create 4 byte of storage before calling
+		(call $seal_set_storage
+			(i32.const 0)		;; Pointer to storage key
+			(i32.const 0)		;; Pointer to value
+			(i32.const 4)		;; Size of value
+		)
+
+		;; call passed contract
+		(call $assert (i32.eqz
+			(call $seal_call
+				(i32.const 0) ;; No flags
+				(i32.const 8)  ;; Pointer to "callee" address.
+				(i64.const 0)  ;; How much gas to devote for the execution. 0 = all.
+				(i32.const 512) ;; Pointer to the buffer with value to transfer
+				(i32.const 4) ;; Pointer to input data buffer address
+				(i32.const 4)  ;; Length of input data buffer
+				(i32.const 4294967295) ;; u32 max value is the sentinel value: do not copy output
+				(i32.const 0) ;; Length is ignored in this case
+			)
+		))
+
+		;; create 8 byte of storage after calling
+		;; item of 12 bytes because we override 4 bytes
+		(call $seal_set_storage
+			(i32.const 0)		;; Pointer to storage key
+			(i32.const 0)		;; Pointer to value
+			(i32.const 12)		;; Size of value
+		)
+	)
+)

frame/contracts/src/benchmarking/mod.rs

@@ -87,7 +87,7 @@ where
 		module: WasmModule<T>,
 		data: Vec<u8>,
 	) -> Result<Contract<T>, &'static str> {
-		let value = T::Currency::minimum_balance();
+		let value = Pallet::<T>::min_balance();
 		T::Currency::make_free_balance_be(&caller, caller_funding::<T>());
 		let salt = vec![0xff];
 		let addr = Contracts::<T>::contract_address(&caller, &module.hash, &salt);
@@ -257,7 +257,7 @@ benchmarks! {
 		let instance = Contract::<T>::with_caller(
 			whitelisted_caller(), WasmModule::sized(c, Location::Deploy), vec![],
 		)?;
-		let value = T::Currency::minimum_balance();
+		let value = Pallet::<T>::min_balance();
 		let origin = RawOrigin::Signed(instance.caller.clone());
 		let callee = instance.addr;
 	}: call(origin, callee, value, Weight::MAX, None, vec![])
@@ -280,7 +280,7 @@ benchmarks! {
 		let c in 0 .. Perbill::from_percent(49).mul_ceil(T::MaxCodeLen::get());
 		let s in 0 .. code::max_pages::<T>() * 64 * 1024;
 		let salt = vec![42u8; s as usize];
-		let value = T::Currency::minimum_balance();
+		let value = Pallet::<T>::min_balance();
 		let caller = whitelisted_caller();
 		T::Currency::make_free_balance_be(&caller, caller_funding::<T>());
 		let WasmModule { code, hash, .. } = WasmModule::<T>::sized(c, Location::Call);
@@ -307,7 +307,7 @@ benchmarks! {
 	instantiate {
 		let s in 0 .. code::max_pages::<T>() * 64 * 1024;
 		let salt = vec![42u8; s as usize];
-		let value = T::Currency::minimum_balance();
+		let value = Pallet::<T>::min_balance();
 		let caller = whitelisted_caller();
 		T::Currency::make_free_balance_be(&caller, caller_funding::<T>());
 		let WasmModule { code, hash, .. } = WasmModule::<T>::dummy();
@@ -338,7 +338,7 @@ benchmarks! {
 		let instance = Contract::<T>::with_caller(
 			whitelisted_caller(), WasmModule::dummy(), vec![],
 		)?;
-		let value = T::Currency::minimum_balance();
+		let value = Pallet::<T>::min_balance();
 		let origin = RawOrigin::Signed(instance.caller.clone());
 		let callee = instance.addr.clone();
 		let before = T::Currency::free_balance(&instance.account_id);
@@ -767,13 +767,13 @@ benchmarks! {
 		let instance = Contract::<T>::new(code, vec![])?;
 		let origin = RawOrigin::Signed(instance.caller.clone());
 		assert_eq!(T::Currency::total_balance(&beneficiary), 0u32.into());
-		assert_eq!(T::Currency::free_balance(&instance.account_id), T::Currency::minimum_balance());
+		assert_eq!(T::Currency::free_balance(&instance.account_id), Pallet::<T>::min_balance());
 		assert_ne!(T::Currency::reserved_balance(&instance.account_id), 0u32.into());
 	}: call(origin, instance.addr.clone(), 0u32.into(), Weight::MAX, None, vec![])
 	verify {
 		if r > 0 {
 			assert_eq!(T::Currency::total_balance(&instance.account_id), 0u32.into());
-			assert_eq!(T::Currency::total_balance(&beneficiary), T::Currency::minimum_balance());
+			assert_eq!(T::Currency::total_balance(&beneficiary), Pallet::<T>::min_balance());
 		}
 	}
 
@@ -1469,7 +1469,7 @@ benchmarks! {
 			.collect::<Vec<_>>();
 		let account_len = accounts.get(0).map(|i| i.encode().len()).unwrap_or(0);
 		let account_bytes = accounts.iter().flat_map(|x| x.encode()).collect();
-		let value = T::Currency::minimum_balance();
+		let value = Pallet::<T>::min_balance();
 		assert!(value > 0u32.into());
 		let value_bytes = value.encode();
 		let value_len = value_bytes.len();
@@ -1705,7 +1705,7 @@ benchmarks! {
 		let hash_len = hashes.get(0).map(|x| x.encode().len()).unwrap_or(0);
 		let hashes_bytes = hashes.iter().flat_map(|x| x.encode()).collect::<Vec<_>>();
 		let hashes_len = hashes_bytes.len();
-		let value = T::Currency::minimum_balance();
+		let value = Pallet::<T>::min_balance();
 		assert!(value > 0u32.into());
 		let value_bytes = value.encode();
 		let value_len = value_bytes.len();

frame/contracts/src/exec.rs

@@ -813,6 +813,15 @@ where
 				return Ok(output)
 			}
 
+			// Storage limit is enforced as late as possible (when the last frame returns) so that
+			// the ordering of storage accesses does not matter.
+			if self.frames.is_empty() {
+				let frame = &mut self.first_frame;
+				frame.contract_info.load(&frame.account_id);
+				let contract = frame.contract_info.as_contract();
+				frame.nested_storage.enforce_limit(contract)?;
+			}
+
 			let frame = self.top_frame();
 			let account_id = &frame.account_id;
 			match (entry_point, delegated_code_hash) {
@@ -911,12 +920,7 @@ where
 			// it was invalidated.
 			frame.contract_info.load(account_id);
 			let mut contract = frame.contract_info.into_contract();
-			prev.nested_storage.absorb(
-				frame.nested_storage,
-				&self.origin,
-				account_id,
-				contract.as_mut(),
-			);
+			prev.nested_storage.absorb(frame.nested_storage, account_id, contract.as_mut());
 
 			// In case the contract wasn't terminated we need to persist changes made to it.
 			if let Some(contract) = contract {
@@ -954,7 +958,6 @@ where
 			let mut contract = self.first_frame.contract_info.as_contract();
 			self.storage_meter.absorb(
 				mem::take(&mut self.first_frame.nested_storage),
-				&self.origin,
 				&self.first_frame.account_id,
 				contract.as_deref_mut(),
 			);
@@ -2354,10 +2357,10 @@ mod tests {
 		let code_bob = MockLoader::insert(Call, |ctx, _| {
 			if ctx.input_data[0] == 0 {
 				let info = ctx.ext.contract_info();
-				assert_eq!(info.storage_deposit, 0);
-				info.storage_deposit = 42;
+				assert_eq!(info.storage_byte_deposit, 0);
+				info.storage_byte_deposit = 42;
 				assert_eq!(ctx.ext.call(Weight::zero(), CHARLIE, 0, vec![], true), exec_trapped());
-				assert_eq!(ctx.ext.contract_info().storage_deposit, 42);
+				assert_eq!(ctx.ext.contract_info().storage_byte_deposit, 42);
 			}
 			exec_success()
 		});

frame/contracts/src/lib.rs

@@ -87,12 +87,12 @@
 mod gas;
 mod benchmarking;
 mod exec;
+mod migration;
 mod schedule;
 mod storage;
 mod wasm;
 
 pub mod chain_extension;
-pub mod migration;
 pub mod weights;
 
 #[cfg(test)]
@@ -109,7 +109,10 @@ use codec::{Encode, HasCompact};
 use frame_support::{
 	dispatch::{DispatchClass, Dispatchable, GetDispatchInfo, Pays, PostDispatchInfo},
 	ensure,
-	traits::{ConstU32, Contains, Currency, Get, Randomness, ReservableCurrency, Time},
+	traits::{
+		tokens::fungible::Inspect, ConstU32, Contains, Currency, Get, Randomness,
+		ReservableCurrency, Time,
+	},
 	weights::Weight,
 	BoundedVec, WeakBoundedVec,
 };
@@ -126,6 +129,7 @@ use sp_std::{fmt::Debug, marker::PhantomData, prelude::*};
 
 pub use crate::{
 	exec::{Frame, VarSizedKey as StorageKey},
+	migration::Migration,
 	pallet::*,
 	schedule::{HostFnWeights, InstructionWeights, Limits, Schedule},
 };
@@ -225,7 +229,7 @@ pub mod pallet {
 	use frame_system::pallet_prelude::*;
 
 	/// The current storage version.
-	const STORAGE_VERSION: StorageVersion = StorageVersion::new(7);
+	const STORAGE_VERSION: StorageVersion = StorageVersion::new(8);
 
 	#[pallet::pallet]
 	#[pallet::storage_version(STORAGE_VERSION)]
@@ -236,11 +240,12 @@ pub mod pallet {
 		/// The time implementation used to supply timestamps to contracts through `seal_now`.
 		type Time: Time;
 
-		/// The generator used to supply randomness to contracts through `seal_random`.
+		/// The generator used to supply randomness to contracts through `seal_random`
 		type Randomness: Randomness<Self::Hash, Self::BlockNumber>;
 
 		/// The currency in which fees are paid and contract balances are held.
-		type Currency: ReservableCurrency<Self::AccountId>;
+		type Currency: ReservableCurrency<Self::AccountId>
+			+ Inspect<Self::AccountId, Balance = BalanceOf<Self>>;
 
 		/// The overarching event type.
 		type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
@@ -1036,7 +1041,7 @@ where
 		};
 		let schedule = T::Schedule::get();
 		let result = ExecStack::<T, PrefabWasmModule<T>>::run_call(
-			origin,
+			origin.clone(),
 			dest,
 			&mut gas_meter,
 			&mut storage_meter,
@@ -1045,7 +1050,11 @@ where
 			data,
 			debug_message,
 		);
-		InternalCallOutput { result, gas_meter, storage_deposit: storage_meter.into_deposit() }
+		InternalCallOutput {
+			result,
+			gas_meter,
+			storage_deposit: storage_meter.into_deposit(&origin),
+		}
 	}
 
 	/// Internal function that does the actual instantiation.
@@ -1089,7 +1098,7 @@ where
 				value.saturating_add(extra_deposit),
 			)?;
 			let result = ExecStack::<T, PrefabWasmModule<T>>::run_instantiate(
-				origin,
+				origin.clone(),
 				executable,
 				&mut gas_meter,
 				&mut storage_meter,
@@ -1100,17 +1109,23 @@ where
 				debug_message,
 			);
 			storage_deposit = storage_meter
-				.into_deposit()
+				.into_deposit(&origin)
 				.saturating_add(&StorageDeposit::Charge(extra_deposit));
 			result
 		};
 		InternalInstantiateOutput { result: try_exec(), gas_meter, storage_deposit }
 	}
 
+	/// Deposit a pallet contracts event. Handles the conversion to the overarching event type.
 	fn deposit_event(topics: Vec<T::Hash>, event: Event<T>) {
 		<frame_system::Pallet<T>>::deposit_event_indexed(
 			&topics,
 			<T as Config>::RuntimeEvent::from(event).into(),
 		)
 	}
+
+	/// Return the existential deposit of [`Config::Currency`].
+	fn min_balance() -> BalanceOf<T> {
+		<T::Currency as Inspect<AccountIdOf<T>>>::minimum_balance()
+	}
 }