L1-294: Safeguards for the inflation parameters setter (#1822) (#1827)

Cherry-pick of [5bfb995](5bfb995) --------- Co-authored-by: lesniak43 <[email protected]>
Cardinal-Cryptography · Oct 8, 2024 · 98cbe53 · 98cbe53
1 parent b43d7fe
commit 98cbe53
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Showing 4 changed files with 102 additions and 6 deletions.
diff --git a/bin/runtime/src/lib.rs b/bin/runtime/src/lib.rs
@@ -42,7 +42,8 @@ use primitives::{
     staking::MAX_NOMINATORS_REWARDED_PER_VALIDATOR, wrap_methods, ApiError as AlephApiError,
     AuraId, AuthorityId as AlephId, Block as AlephBlock, BlockId as AlephBlockId,
     BlockNumber as AlephBlockNumber, Header as AlephHeader, SessionAuthorityData, SessionCommittee,
-    SessionIndex, SessionInfoProvider, SessionValidatorError, Version as FinalityVersion,
+    SessionIndex, SessionInfoProvider, SessionValidatorError,
+    TotalIssuanceProvider as TotalIssuanceProviderT, Version as FinalityVersion,
     ADDRESSES_ENCODING, DEFAULT_BAN_REASON_LENGTH, DEFAULT_MAX_WINNERS, DEFAULT_SESSIONS_PER_ERA,
     DEFAULT_SESSION_PERIOD, MAX_BLOCK_SIZE, MILLISECS_PER_BLOCK, TOKEN,
 };
@@ -335,6 +336,13 @@ impl SessionInfoProvider<AlephBlockNumber> for SessionInfoImpl {
     }
 }
 
+pub struct TotalIssuanceProvider;
+impl TotalIssuanceProviderT for TotalIssuanceProvider {
+    fn get() -> Balance {
+        pallet_balances::Pallet::<Runtime>::total_issuance()
+    }
+}
+
 impl pallet_aleph::Config for Runtime {
     type AuthorityId = AlephId;
     type RuntimeEvent = RuntimeEvent;
@@ -346,6 +354,7 @@ impl pallet_aleph::Config for Runtime {
         Runtime,
     >;
     type NextSessionAuthorityProvider = Session;
+    type TotalIssuanceProvider = TotalIssuanceProvider;
 }
 
 #[cfg(feature = "liminal")]

diff --git a/pallets/aleph/src/lib.rs b/pallets/aleph/src/lib.rs
@@ -33,7 +33,7 @@ pub mod pallet {
         pallet_prelude::{BlockNumberFor, OriginFor},
     };
     use pallet_session::SessionManager;
-    use primitives::SessionInfoProvider;
+    use primitives::{SessionInfoProvider, TotalIssuanceProvider};
     use sp_std::collections::btree_set::BTreeSet;
     #[cfg(feature = "std")]
     use sp_std::marker::PhantomData;
@@ -48,6 +48,7 @@ pub mod pallet {
         type SessionInfoProvider: SessionInfoProvider<BlockNumberFor<Self>>;
         type SessionManager: SessionManager<<Self as frame_system::Config>::AccountId>;
         type NextSessionAuthorityProvider: NextSessionAuthorityProvider<Self>;
+        type TotalIssuanceProvider: TotalIssuanceProvider;
     }
 
     #[pallet::event]
@@ -242,6 +243,64 @@ pub mod pallet {
 
             Self::finality_version()
         }
+
+        pub fn check_horizon_upper_bound(
+            new_horizon: u64,
+            current_horizon: u64,
+        ) -> Result<(), &'static str> {
+            match new_horizon > current_horizon.saturating_mul(2).saturating_add(1) {
+                true => {
+                    Err("Horizon too large, should be at most twice the current value plus one!")
+                }
+                false => Ok(()),
+            }
+        }
+
+        pub fn check_horizon_lower_bound(
+            new_horizon: u64,
+            current_horizon: u64,
+        ) -> Result<(), &'static str> {
+            match new_horizon < current_horizon / 2 {
+                true => Err("Horizon too small, should be at least half the current value!"),
+                false => Ok(()),
+            }
+        }
+
+        pub fn check_azero_cap_upper_bound(
+            new_cap: Balance,
+            current_cap: Balance,
+            total_issuance: Balance,
+        ) -> Result<(), &'static str> {
+            let current_gap = current_cap.saturating_sub(total_issuance);
+            let new_gap = match new_cap.checked_sub(total_issuance) {
+                Some(new_gap) => new_gap,
+                None => return Err("AZERO Cap cannot be lower than the current total issuance!"),
+            };
+            match (new_gap > current_gap.saturating_mul(2).saturating_add(1))
+                && (new_gap > total_issuance / 128)
+            {
+                true => Err("Future issuance too large, should be at most the current total issuance divided by 128, or at most twice the current value plus one!"),
+                false => Ok(()),
+            }
+        }
+
+        pub fn check_azero_cap_lower_bound(
+            new_cap: Balance,
+            current_cap: Balance,
+            total_issuance: Balance,
+        ) -> Result<(), &'static str> {
+            let current_gap = current_cap.saturating_sub(total_issuance);
+            let new_gap = match new_cap.checked_sub(total_issuance) {
+                Some(new_gap) => new_gap,
+                None => return Err("AZERO Cap cannot be lower than the current total issuance!"),
+            };
+            match new_gap < current_gap / 2 {
+                true => {
+                    Err("Future issuance too small, should be at least half the current value!")
+                }
+                false => Ok(()),
+            }
+        }
     }
 
     #[pallet::call]
@@ -298,9 +357,21 @@ pub mod pallet {
         ) -> DispatchResult {
             ensure_root(origin)?;
 
-            let azero_cap = azero_cap.unwrap_or_else(AzeroCap::<T>::get);
-            let horizon_millisecs =
-                horizon_millisecs.unwrap_or_else(ExponentialInflationHorizon::<T>::get);
+            let current_azero_cap = AzeroCap::<T>::get();
+            let current_horizon_millisecs = ExponentialInflationHorizon::<T>::get();
+            let total_issuance = T::TotalIssuanceProvider::get();
+
+            let azero_cap = azero_cap.unwrap_or(current_azero_cap);
+            let horizon_millisecs = horizon_millisecs.unwrap_or(current_horizon_millisecs);
+
+            Self::check_horizon_lower_bound(horizon_millisecs, current_horizon_millisecs)
+                .map_err(DispatchError::Other)?;
+            Self::check_horizon_upper_bound(horizon_millisecs, current_horizon_millisecs)
+                .map_err(DispatchError::Other)?;
+            Self::check_azero_cap_upper_bound(azero_cap, current_azero_cap, total_issuance)
+                .map_err(DispatchError::Other)?;
+            Self::check_azero_cap_lower_bound(azero_cap, current_azero_cap, total_issuance)
+                .map_err(DispatchError::Other)?;
 
             AzeroCap::<T>::put(azero_cap);
             ExponentialInflationHorizon::<T>::put(horizon_millisecs);

diff --git a/pallets/aleph/src/mock.rs b/pallets/aleph/src/mock.rs
@@ -8,7 +8,9 @@ use frame_support::{
     weights::{RuntimeDbWeight, Weight},
 };
 use frame_system::pallet_prelude::BlockNumberFor;
-use primitives::{AuthorityId, SessionInfoProvider};
+use primitives::{
+    AuthorityId, SessionInfoProvider, TotalIssuanceProvider as TotalIssuanceProviderT,
+};
 use sp_core::H256;
 use sp_runtime::{
     impl_opaque_keys,
@@ -147,12 +149,20 @@ impl pallet_timestamp::Config for Test {
     type WeightInfo = ();
 }
 
+pub struct TotalIssuanceProvider;
+impl TotalIssuanceProviderT for TotalIssuanceProvider {
+    fn get() -> Balance {
+        pallet_balances::Pallet::<Test>::total_issuance()
+    }
+}
+
 impl Config for Test {
     type AuthorityId = AuthorityId;
     type RuntimeEvent = RuntimeEvent;
     type SessionInfoProvider = SessionInfoImpl;
     type SessionManager = ();
     type NextSessionAuthorityProvider = Session;
+    type TotalIssuanceProvider = TotalIssuanceProvider;
 }
 
 pub fn to_authority(id: &u64) -> AuthorityId {

diff --git a/primitives/src/lib.rs b/primitives/src/lib.rs
@@ -337,6 +337,12 @@ pub trait EraManager {
     fn on_new_era(era: EraIndex);
 }
 
+/// Provides the current total issuance.
+pub trait TotalIssuanceProvider {
+    /// Get the current total issuance.
+    fn get() -> Balance;
+}
+
 pub mod staking {
     use crate::TOKEN;