beefy: put not only lease parachain heads into mmr

polkadot/runtime/parachains/src/paras/mod.rs

@@ -1221,6 +1221,15 @@ const INVALID_TX_BAD_VALIDATOR_IDX: u8 = 1;
 const INVALID_TX_BAD_SUBJECT: u8 = 2;
 const INVALID_TX_DOUBLE_VOTE: u8 = 3;
 
+/// This is intermediate "fix" for this issue:
+/// https://github.com/orgs/paritytech/projects/119/views/20?pane=issue&itemId=66568838
+///
+/// It does not actually fix it, but makes the worst case better. Without that limit someone
+/// could completely DoS the relay chain by registering a ridiculously high amount of paras.
+/// With this limit the same attack could lead to some parachains ceasing to being able to
+/// communicate via snowbridge.
+pub const MAX_PARA_HEADS: usize = 1024;
+
 impl<T: Config> Pallet<T> {
 	/// This is a call to schedule code upgrades for parachains which is safe to be called
 	/// outside of this module. That means this function does all checks necessary to ensure
@@ -1290,6 +1299,16 @@ impl<T: Config> Pallet<T> {
 		})
 	}
 
+	/// Get a list of the first [`MAX_PARA_HEADS`] para heads sorted by para_id.
+	/// This method is likely to be removed in the future.
+	pub fn sorted_para_heads() -> Vec<(u32, Vec<u8>)> {
+		let mut heads: Vec<(u32, Vec<u8>)> =
+			Heads::<T>::iter().map(|(id, head)| (id.into(), head.0)).collect();
+		heads.sort_by_key(|(id, _)| *id);
+		heads.truncate(MAX_PARA_HEADS);
+		heads
+	}
+
 	// Apply all para actions queued for the given session index.
 	//
 	// The actions to take are based on the lifecycle of of the paras.

polkadot/runtime/rococo/src/lib.rs

@@ -1301,13 +1301,8 @@ parameter_types! {
 pub struct ParaHeadsRootProvider;
 impl BeefyDataProvider<H256> for ParaHeadsRootProvider {
 	fn extra_data() -> H256 {
-		let mut para_heads: Vec<(u32, Vec<u8>)> = parachains_paras::Parachains::<Runtime>::get()
-			.into_iter()
-			.filter_map(|id| {
-				parachains_paras::Heads::<Runtime>::get(&id).map(|head| (id.into(), head.0))
-			})
-			.collect();
-		para_heads.sort();
+		let para_heads: Vec<(u32, Vec<u8>)> =
+			parachains_paras::Pallet::<Runtime>::sorted_para_heads();
 		binary_merkle_tree::merkle_root::<mmr::Hashing, _>(
 			para_heads.into_iter().map(|pair| pair.encode()),
 		)

polkadot/runtime/westend/src/lib.rs

@@ -357,13 +357,8 @@ parameter_types! {
 pub struct ParaHeadsRootProvider;
 impl BeefyDataProvider<H256> for ParaHeadsRootProvider {
 	fn extra_data() -> H256 {
-		let mut para_heads: Vec<(u32, Vec<u8>)> = parachains_paras::Parachains::<Runtime>::get()
-			.into_iter()
-			.filter_map(|id| {
-				parachains_paras::Heads::<Runtime>::get(&id).map(|head| (id.into(), head.0))
-			})
-			.collect();
-		para_heads.sort_by_key(|k| k.0);
+		let para_heads: Vec<(u32, Vec<u8>)> =
+			parachains_paras::Pallet::<Runtime>::sorted_para_heads();
 		binary_merkle_tree::merkle_root::<mmr::Hashing, _>(
 			para_heads.into_iter().map(|pair| pair.encode()),
 		)

prdoc/pr_4751.prdoc

@@ -0,0 +1,12 @@
+title: "Use all parachain heads for BEEFY MMR extra data"
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      Previously, the extra data in an MMR leaf nodes was only computed based on lease-based parachain heads.
+      This PR extends the extra data to include others, including on-demand parachain heads.
+      Currently, the number of heads is limited to the first 1024 heads sorted by para id.
+
+crates:
+  - name: polkadot-runtime-parachains
+    bump: minor