blockstore: send duplicate proofs for chained merkle root conflicts

core/src/window_service.rs

@@ -169,6 +169,11 @@ fn run_check_duplicate(
             shred_slot,
             &root_bank,
         );
+        let chained_merkle_conflict_duplicate_proofs = cluster_nodes::check_feature_activation(
+            &feature_set::chained_merkle_conflict_duplicate_proofs::id(),
+            shred_slot,
+            &root_bank,
+        );
         let (shred1, shred2) = match shred {
             PossibleDuplicateShred::LastIndexConflict(shred, conflict)
             | PossibleDuplicateShred::ErasureConflict(shred, conflict) => {
@@ -196,6 +201,24 @@ fn run_check_duplicate(
                     return Ok(());
                 }
             }
+            PossibleDuplicateShred::ChainedMerkleRootConflict(shred, conflict) => {
+                if chained_merkle_conflict_duplicate_proofs {
+                    // Although this proof can be immediately stored on detection, we wait until
+                    // here in order to check the feature flag, as storage in blockstore can
+                    // preclude the detection of other duplicate proofs in this slot
+                    if blockstore.has_duplicate_shreds_in_slot(shred_slot) {
+                        return Ok(());
+                    }
+                    blockstore.store_duplicate_slot(
+                        shred_slot,
+                        conflict.clone(),
+                        shred.clone().into_payload(),
+                    )?;
+                    (shred, conflict)
+                } else {
+                    return Ok(());
+                }
+            }
             PossibleDuplicateShred::Exists(shred) => {
                 // Unlike the other cases we have to wait until here to decide to handle the duplicate and store
                 // in blockstore. This is because the duplicate could have been part of the same insert batch,

ledger/src/blockstore.rs

@@ -146,6 +146,7 @@ pub enum PossibleDuplicateShred {
     LastIndexConflict(/* original */ Shred, /* conflict */ Vec<u8>), // The index of this shred conflicts with `slot_meta.last_index`
     ErasureConflict(/* original */ Shred, /* conflict */ Vec<u8>), // The coding shred has a conflict in the erasure_meta
     MerkleRootConflict(/* original */ Shred, /* conflict */ Vec<u8>), // Merkle root conflict in the same fec set
+    ChainedMerkleRootConflict(/* original */ Shred, /* conflict */ Vec<u8>), // Merkle root chaining conflict with previous fec set
 }
 
 impl PossibleDuplicateShred {
@@ -155,6 +156,7 @@ impl PossibleDuplicateShred {
             Self::LastIndexConflict(shred, _) => shred.slot(),
             Self::ErasureConflict(shred, _) => shred.slot(),
             Self::MerkleRootConflict(shred, _) => shred.slot(),
+            Self::ChainedMerkleRootConflict(shred, _) => shred.slot(),
         }
     }
 }
@@ -1283,6 +1285,18 @@ impl Blockstore {
                     return false;
                 }
             }
+
+            // Check that the chaining between our current shred, the previous fec_set
+            // and the next fec_set
+            if !self.check_chained_merkle_root_consistency(
+                just_received_shreds,
+                &erasure_set,
+                merkle_root_metas,
+                &shred,
+                duplicate_shreds,
+            ) {
+                return false;
+            }
         }
 
         let erasure_meta_entry = erasure_metas.entry(erasure_set).or_insert_with(|| {
@@ -1517,6 +1531,18 @@ impl Blockstore {
                     return Err(InsertDataShredError::InvalidShred);
                 }
             }
+
+            // Check that the chaining between our current shred, the previous fec_set
+            // and the next fec_set
+            if !self.check_chained_merkle_root_consistency(
+                just_inserted_shreds,
+                &erasure_set,
+                merkle_root_metas,
+                &shred,
+                duplicate_shreds,
+            ) {
+                return Err(InsertDataShredError::InvalidShred);
+            }
         }
 
         let newly_completed_data_sets = self.insert_data_shred(
@@ -1648,6 +1674,110 @@ impl Blockstore {
         false
     }
 
+    /// Returns true if there is no chaining conflict between
+    /// the `shred` and `merkle_root_meta` of the next or previous
+    /// FEC set, or if shreds from the next or previous set are
+    /// yet to be received.
+    ///
+    /// Otherwise return false and add duplicate proof to
+    /// `duplicate_shreds`.
+    fn check_chained_merkle_root_consistency(
+        &self,
+        just_inserted_shreds: &HashMap<ShredId, Shred>,
+        erasure_set: &ErasureSetId,
+        merkle_root_metas: &HashMap<ErasureSetId, WorkingEntry<MerkleRootMeta>>,
+        shred: &Shred,
+        duplicate_shreds: &mut Vec<PossibleDuplicateShred>,
+    ) -> bool {
+        let (slot, fec_set_index) = erasure_set.store_key();
+
+        let next_erasure_set = ErasureSetId::new(slot, fec_set_index + 1);
+        if let Some(next_merkle_root_meta) =
+            merkle_root_metas.get(&next_erasure_set).map(AsRef::as_ref)
+        {
+            let next_shred_id = ShredId::new(
+                slot,
+                next_merkle_root_meta.first_received_shred_index(),
+                next_merkle_root_meta.first_received_shred_type(),
+            );
+            let next_shred =
+                Self::get_shred_from_just_inserted_or_db(self, just_inserted_shreds, next_shred_id)
+                    .expect("Shred indicated by merkle root meta must exist")
+                    .into_owned();
+            let next_shred = Shred::new_from_serialized_shred(next_shred)
+                .expect("Shred indicated by merkle root meta should deserialize");
+
+            if !self.check_chaining(shred, &next_shred, duplicate_shreds) {
+                return false;
+            }
+        }
+
+        if fec_set_index == 0 {
+            // Although the first fec set chains to the last fec set of the parent block,
+            // if this chain is incorrect we do not which block is the duplicate until votes
+            // are received. We instead delay this check until the block reaches duplicate
+            // confirmation.
+            return true;
+        }
+        let prev_erasure_set = ErasureSetId::new(slot, fec_set_index - 1);
+        if let Some(prev_merkle_root_meta) =
+            merkle_root_metas.get(&prev_erasure_set).map(AsRef::as_ref)
+        {
+            let prev_shred_id = ShredId::new(
+                slot,
+                prev_merkle_root_meta.first_received_shred_index(),
+                prev_merkle_root_meta.first_received_shred_type(),
+            );
+            let prev_shred =
+                Self::get_shred_from_just_inserted_or_db(self, just_inserted_shreds, prev_shred_id)
+                    .expect("Shred indicated by merkle root meta must exist")
+                    .into_owned();
+            let prev_shred = Shred::new_from_serialized_shred(prev_shred)
+                .expect("Shred indicated by merkle root meta should deserialize");
+            if !self.check_chaining(&prev_shred, shred, duplicate_shreds) {
+                return false;
+            }
+        }
+
+        true
+    }
+
+    /// Checks if the chained merkle root of `next_shred` == `prev_shred`'s merkle root.
+    ///
+    /// Returns true if no conflict, otherwise updates duplicate_shreds
+    fn check_chaining(
+        &self,
+        prev_shred: &Shred,
+        next_shred: &Shred,
+        duplicate_shreds: &mut Vec<PossibleDuplicateShred>,
+    ) -> bool {
+        let merkle_root = prev_shred.merkle_root().ok();
+        let chained_merkle_root = next_shred.chained_merkle_root().ok();
+        if merkle_root == chained_merkle_root {
+            return true;
+        }
+        warn!(
+            "Received conflicting chained merkle roots for slot: {},
+                shred {:?} type {:?} has merkle root {:?}, however
+                next shred {:?} type {:?} chains to merkle root {:?}. Reporting as duplicate",
+            prev_shred.slot(),
+            prev_shred.erasure_set(),
+            prev_shred.shred_type(),
+            merkle_root,
+            next_shred.erasure_set(),
+            next_shred.shred_type(),
+            chained_merkle_root,
+        );
+
+        if !self.has_duplicate_shreds_in_slot(prev_shred.slot()) {
+            duplicate_shreds.push(PossibleDuplicateShred::ChainedMerkleRootConflict(
+                prev_shred.clone(),
+                next_shred.payload().clone(),
+            ));
+        }
+        false
+    }
+
     fn should_insert_data_shred(
         &self,
         shred: &Shred,

ledger/src/shred.rs

@@ -286,6 +286,10 @@ impl ShredId {
 pub(crate) struct ErasureSetId(Slot, /*fec_set_index:*/ u32);
 
 impl ErasureSetId {
+    pub(crate) fn new(slot: Slot, fec_set_index: u32) -> Self {
+        Self(slot, fec_set_index)
+    }
+
     pub(crate) fn slot(&self) -> Slot {
         self.0
     }
@@ -342,6 +346,7 @@ impl Shred {
     dispatch!(pub(crate) fn erasure_shard_index(&self) -> Result<usize, Error>);
 
     dispatch!(pub fn into_payload(self) -> Vec<u8>);
+    dispatch!(pub fn chained_merkle_root(&self) -> Result<Hash, Error>);
     dispatch!(pub fn merkle_root(&self) -> Result<Hash, Error>);
     dispatch!(pub fn payload(&self) -> &Vec<u8>);
     dispatch!(pub fn sanitize(&self) -> Result<(), Error>);

ledger/src/shred/merkle.rs

@@ -181,6 +181,14 @@ impl ShredData {
         Ok(Self::SIZE_OF_HEADERS + Self::capacity(proof_size, /*chained:*/ true)?)
     }
 
+    pub(super) fn chained_merkle_root(&self) -> Result<Hash, Error> {
+        let offset = self.chained_merkle_root_offset()?;
+        self.payload
+            .get(offset..offset + SIZE_OF_MERKLE_ROOT)
+            .map(Hash::new)
+            .ok_or(Error::InvalidPayloadSize(self.payload.len()))
+    }
+
     fn set_chained_merkle_root(&mut self, chained_merkle_root: &Hash) -> Result<(), Error> {
         let offset = self.chained_merkle_root_offset()?;
         let Some(buffer) = self.payload.get_mut(offset..offset + SIZE_OF_MERKLE_ROOT) else {
@@ -328,7 +336,7 @@ impl ShredCode {
         Ok(Self::SIZE_OF_HEADERS + Self::capacity(proof_size, /*chained:*/ true)?)
     }
 
-    fn chained_merkle_root(&self) -> Result<Hash, Error> {
+    pub(super) fn chained_merkle_root(&self) -> Result<Hash, Error> {
         let offset = self.chained_merkle_root_offset()?;
         self.payload
             .get(offset..offset + SIZE_OF_MERKLE_ROOT)

ledger/src/shred/shred_code.rs

@@ -47,6 +47,13 @@ impl ShredCode {
         }
     }
 
+    pub(super) fn chained_merkle_root(&self) -> Result<Hash, Error> {
+        match self {
+            Self::Legacy(_) => Err(Error::InvalidShredType),
+            Self::Merkle(shred) => shred.chained_merkle_root(),
+        }
+    }
+
     pub(super) fn merkle_root(&self) -> Result<Hash, Error> {
         match self {
             Self::Legacy(_) => Err(Error::InvalidShredType),

ledger/src/shred/shred_data.rs

@@ -41,6 +41,13 @@ impl ShredData {
         }
     }
 
+    pub(super) fn chained_merkle_root(&self) -> Result<Hash, Error> {
+        match self {
+            Self::Legacy(_) => Err(Error::InvalidShredType),
+            Self::Merkle(shred) => shred.chained_merkle_root(),
+        }
+    }
+
     pub(super) fn merkle_root(&self) -> Result<Hash, Error> {
         match self {
             Self::Legacy(_) => Err(Error::InvalidShredType),

sdk/src/feature_set.rs

@@ -776,6 +776,10 @@ pub mod enable_gossip_duplicate_proof_ingestion {
     solana_sdk::declare_id!("FNKCMBzYUdjhHyPdsKG2LSmdzH8TCHXn3ytj8RNBS4nG");
 }
 
+pub mod chained_merkle_conflict_duplicate_proofs {
+    solana_sdk::declare_id!("chaie9S2zVfuxJKNRGkyTDokLwWxx6kD2ZLsqQHaDD8");
+}
+
 pub mod enable_chained_merkle_shreds {
     solana_sdk::declare_id!("7uZBkJXJ1HkuP6R3MJfZs7mLwymBcDbKdqbF51ZWLier");
 }
@@ -975,6 +979,7 @@ lazy_static! {
         (enable_gossip_duplicate_proof_ingestion::id(), "enable gossip duplicate proof ingestion #32963"),
         (enable_chained_merkle_shreds::id(), "Enable chained Merkle shreds #34916"),
         (remove_rounding_in_fee_calculation::id(), "Removing unwanted rounding in fee calculation #34982"),
+        (chained_merkle_conflict_duplicate_proofs::id(), "generate duplicate proofs for chained merkle root conflicts #"),
         /*************** ADD NEW FEATURES HERE ***************/
     ]
     .iter()