Data column gossip validation and error handling (#6181)

* Add gossip verification and error handling.

* Merge branch 'unstable' into das-gossip-validation

* Add inclusion proof verification and some renames for consistency

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -52,8 +52,8 @@ use crate::observed_aggregates::{
 use crate::observed_attesters::{
     ObservedAggregators, ObservedAttesters, ObservedSyncAggregators, ObservedSyncContributors,
 };
-use crate::observed_blob_sidecars::ObservedBlobSidecars;
 use crate::observed_block_producers::ObservedBlockProducers;
+use crate::observed_data_sidecars::ObservedDataSidecars;
 use crate::observed_operations::{ObservationOutcome, ObservedOperations};
 use crate::observed_slashable::ObservedSlashable;
 use crate::persisted_beacon_chain::{PersistedBeaconChain, DUMMY_CANONICAL_HEAD_BLOCK_ROOT};
@@ -415,7 +415,9 @@ pub struct BeaconChain<T: BeaconChainTypes> {
     /// Maintains a record of which validators have proposed blocks for each slot.
     pub observed_block_producers: RwLock<ObservedBlockProducers<T::EthSpec>>,
     /// Maintains a record of blob sidecars seen over the gossip network.
-    pub observed_blob_sidecars: RwLock<ObservedBlobSidecars<T::EthSpec>>,
+    pub observed_blob_sidecars: RwLock<ObservedDataSidecars<BlobSidecar<T::EthSpec>>>,
+    /// Maintains a record of column sidecars seen over the gossip network.
+    pub observed_column_sidecars: RwLock<ObservedDataSidecars<DataColumnSidecar<T::EthSpec>>>,
     /// Maintains a record of slashable message seen over the gossip network or RPC.
     pub observed_slashable: RwLock<ObservedSlashable<T::EthSpec>>,
     /// Maintains a record of which validators have submitted voluntary exits.

beacon_node/beacon_chain/src/builder.rs

@@ -11,6 +11,7 @@ use crate::graffiti_calculator::{GraffitiCalculator, GraffitiOrigin};
 use crate::head_tracker::HeadTracker;
 use crate::light_client_server_cache::LightClientServerCache;
 use crate::migrate::{BackgroundMigrator, MigratorConfig};
+use crate::observed_data_sidecars::ObservedDataSidecars;
 use crate::persisted_beacon_chain::PersistedBeaconChain;
 use crate::shuffling_cache::{BlockShufflingIds, ShufflingCache};
 use crate::validator_monitor::{ValidatorMonitor, ValidatorMonitorConfig};
@@ -917,7 +918,8 @@ where
             observed_sync_aggregators: <_>::default(),
             // TODO: allow for persisting and loading the pool from disk.
             observed_block_producers: <_>::default(),
-            observed_blob_sidecars: <_>::default(),
+            observed_column_sidecars: RwLock::new(ObservedDataSidecars::new(self.spec.clone())),
+            observed_blob_sidecars: RwLock::new(ObservedDataSidecars::new(self.spec.clone())),
             observed_slashable: <_>::default(),
             observed_voluntary_exits: <_>::default(),
             observed_proposer_slashings: <_>::default(),

beacon_node/beacon_chain/src/data_column_verification.rs

@@ -1,13 +1,21 @@
-use crate::block_verification::{process_block_slash_info, BlockSlashInfo};
+use crate::block_verification::{
+    cheap_state_advance_to_obtain_committees, get_validator_pubkey_cache, process_block_slash_info,
+    BlockSlashInfo,
+};
 use crate::{BeaconChain, BeaconChainError, BeaconChainTypes};
 use derivative::Derivative;
+use fork_choice::ProtoBlock;
 use kzg::{Error as KzgError, Kzg};
+use proto_array::Block;
+use slasher::test_utils::E;
+use slog::debug;
+use slot_clock::SlotClock;
 use ssz_derive::{Decode, Encode};
 use std::sync::Arc;
 use types::data_column_sidecar::{ColumnIndex, DataColumnIdentifier};
 use types::{
-    BeaconStateError, DataColumnSidecar, EthSpec, Hash256, RuntimeVariableList,
-    SignedBeaconBlockHeader, Slot,
+    BeaconStateError, ChainSpec, DataColumnSidecar, DataColumnSubnetId, EthSpec, Hash256,
+    RuntimeVariableList, SignedBeaconBlockHeader, Slot,
 };
 
 /// An error occurred while validating a gossip data column.
@@ -54,6 +62,75 @@ pub enum GossipDataColumnError {
     ///
     /// The data column sidecar is invalid and the peer is faulty.
     InvalidKzgProof(kzg::Error),
+    /// The column was gossiped over an incorrect subnet.
+    ///
+    /// ## Peer scoring
+    ///
+    /// The column is invalid or the peer is faulty.
+    InvalidSubnetId { received: u64, expected: u64 },
+    /// The column sidecar is from a slot that is later than the current slot (with respect to the
+    /// gossip clock disparity).
+    ///
+    /// ## Peer scoring
+    ///
+    /// Assuming the local clock is correct, the peer has sent an invalid message.
+    FutureSlot {
+        message_slot: Slot,
+        latest_permissible_slot: Slot,
+    },
+    /// The sidecar corresponds to a slot older than the finalized head slot.
+    ///
+    /// ## Peer scoring
+    ///
+    /// It's unclear if this column is valid, but this column is for a finalized slot and is
+    /// therefore useless to us.
+    PastFinalizedSlot {
+        column_slot: Slot,
+        finalized_slot: Slot,
+    },
+    /// The pubkey cache timed out.
+    ///
+    /// ## Peer scoring
+    ///
+    /// The column sidecar may be valid, this is an internal error.
+    PubkeyCacheTimeout,
+    /// The proposer index specified in the sidecar does not match the locally computed
+    /// proposer index.
+    ///
+    /// ## Peer scoring
+    ///
+    /// The column is invalid and the peer is faulty.
+    ProposerIndexMismatch { sidecar: usize, local: usize },
+    /// The provided columns's parent block is unknown.
+    ///
+    /// ## Peer scoring
+    ///
+    /// We cannot process the columns without validating its parent, the peer isn't necessarily faulty.
+    ParentUnknown { parent_root: Hash256 },
+    /// The column conflicts with finalization, no need to propagate.
+    ///
+    /// ## Peer scoring
+    ///
+    /// It's unclear if this column is valid, but it conflicts with finality and shouldn't be
+    /// imported.
+    NotFinalizedDescendant { block_parent_root: Hash256 },
+    /// Invalid kzg commitment inclusion proof
+    ///
+    /// ## Peer scoring
+    ///
+    /// The column sidecar is invalid and the peer is faulty
+    InvalidInclusionProof,
+    /// A column has already been seen for the given `(sidecar.block_root, sidecar.index)` tuple
+    /// over gossip or no gossip sources.
+    ///
+    /// ## Peer scoring
+    ///
+    /// The peer isn't faulty, but we do not forward it over gossip.
+    PriorKnown {
+        proposer: u64,
+        slot: Slot,
+        index: ColumnIndex,
+    },
 }
 
 impl From<BeaconChainError> for GossipDataColumnError {
@@ -183,18 +260,254 @@ where
 
 pub fn validate_data_column_sidecar_for_gossip<T: BeaconChainTypes>(
     data_column: Arc<DataColumnSidecar<T::EthSpec>>,
-    _subnet: u64,
+    subnet: u64,
     chain: &BeaconChain<T>,
 ) -> Result<GossipVerifiedDataColumn<T>, GossipDataColumnError> {
-    // TODO(das): implement gossip verification
+    let column_slot = data_column.slot();
+
+    verify_index_matches_subnet(&data_column, subnet, &chain.spec)?;
+    verify_sidecar_not_from_future_slot(chain, column_slot)?;
+    verify_slot_greater_than_latest_finalized_slot(chain, column_slot)?;
+    verify_is_first_sidecar(chain, &data_column)?;
+    verify_column_inclusion_proof(&data_column)?;
+    let parent_block = verify_parent_block_and_finalized_descendant(data_column.clone(), chain)?;
+    verify_slot_higher_than_parent(&parent_block, column_slot)?;
+    verify_proposer_and_signature(&data_column, &parent_block, chain)?;
     let kzg = chain
         .kzg
         .clone()
         .ok_or(GossipDataColumnError::KzgNotInitialized)?;
     let kzg_verified_data_column = verify_kzg_for_data_column(data_column.clone(), &kzg)
         .map_err(GossipDataColumnError::InvalidKzgProof)?;
+
+    chain
+        .observed_slashable
+        .write()
+        .observe_slashable(
+            column_slot,
+            data_column.block_proposer_index(),
+            data_column.block_root(),
+        )
+        .map_err(|e| GossipDataColumnError::BeaconChainError(e.into()))?;
+
     Ok(GossipVerifiedDataColumn {
         block_root: data_column.block_root(),
         data_column: kzg_verified_data_column,
     })
 }
+
+// Verify that this is the first column sidecar received for the tuple:
+// (block_header.slot, block_header.proposer_index, column_sidecar.index)
+fn verify_is_first_sidecar<T: BeaconChainTypes>(
+    chain: &BeaconChain<T>,
+    data_column: &DataColumnSidecar<T::EthSpec>,
+) -> Result<(), GossipDataColumnError> {
+    if chain
+        .observed_column_sidecars
+        .read()
+        .proposer_is_known(data_column)
+        .map_err(|e| GossipDataColumnError::BeaconChainError(e.into()))?
+    {
+        return Err(GossipDataColumnError::PriorKnown {
+            proposer: data_column.block_proposer_index(),
+            slot: data_column.slot(),
+            index: data_column.index,
+        });
+    }
+    Ok(())
+}
+
+fn verify_column_inclusion_proof<E: EthSpec>(
+    data_column: &DataColumnSidecar<E>,
+) -> Result<(), GossipDataColumnError> {
+    if !data_column.verify_inclusion_proof() {
+        return Err(GossipDataColumnError::InvalidInclusionProof);
+    }
+    Ok(())
+}
+
+fn verify_slot_higher_than_parent(
+    parent_block: &Block,
+    data_column_slot: Slot,
+) -> Result<(), GossipDataColumnError> {
+    if parent_block.slot >= data_column_slot {
+        return Err(GossipDataColumnError::IsNotLaterThanParent {
+            data_column_slot,
+            parent_slot: parent_block.slot,
+        });
+    }
+    Ok(())
+}
+
+fn verify_parent_block_and_finalized_descendant<T: BeaconChainTypes>(
+    data_column: Arc<DataColumnSidecar<T::EthSpec>>,
+    chain: &BeaconChain<T>,
+) -> Result<ProtoBlock, GossipDataColumnError> {
+    let fork_choice = chain.canonical_head.fork_choice_read_lock();
+
+    // We have already verified that the column is past finalization, so we can
+    // just check fork choice for the block's parent.
+    let block_parent_root = data_column.block_parent_root();
+    let Some(parent_block) = fork_choice.get_block(&block_parent_root) else {
+        return Err(GossipDataColumnError::ParentUnknown {
+            parent_root: block_parent_root,
+        });
+    };
+
+    // Do not process a column that does not descend from the finalized root.
+    // We just loaded the parent_block, so we can be sure that it exists in fork choice.
+    if !fork_choice.is_finalized_checkpoint_or_descendant(block_parent_root) {
+        return Err(GossipDataColumnError::NotFinalizedDescendant { block_parent_root });
+    }
+
+    Ok(parent_block)
+}
+
+fn verify_proposer_and_signature<T: BeaconChainTypes>(
+    data_column: &DataColumnSidecar<T::EthSpec>,
+    parent_block: &ProtoBlock,
+    chain: &BeaconChain<T>,
+) -> Result<(), GossipDataColumnError> {
+    let column_slot = data_column.slot();
+    let column_epoch = column_slot.epoch(E::slots_per_epoch());
+    let column_index = data_column.index;
+    let block_root = data_column.block_root();
+    let block_parent_root = data_column.block_parent_root();
+
+    let proposer_shuffling_root =
+        if parent_block.slot.epoch(T::EthSpec::slots_per_epoch()) == column_epoch {
+            parent_block
+                .next_epoch_shuffling_id
+                .shuffling_decision_block
+        } else {
+            parent_block.root
+        };
+
+    let proposer_opt = chain
+        .beacon_proposer_cache
+        .lock()
+        .get_slot::<T::EthSpec>(proposer_shuffling_root, column_slot);
+
+    let (proposer_index, fork) = if let Some(proposer) = proposer_opt {
+        (proposer.index, proposer.fork)
+    } else {
+        debug!(
+            chain.log,
+            "Proposer shuffling cache miss for column verification";
+            "block_root" => %block_root,
+            "index" => %column_index,
+        );
+        let (parent_state_root, mut parent_state) = chain
+            .store
+            .get_advanced_hot_state(block_parent_root, column_slot, parent_block.state_root)
+            .map_err(|e| GossipDataColumnError::BeaconChainError(e.into()))?
+            .ok_or_else(|| {
+                BeaconChainError::DBInconsistent(format!(
+                    "Missing state for parent block {block_parent_root:?}",
+                ))
+            })?;
+
+        let state = cheap_state_advance_to_obtain_committees::<_, GossipDataColumnError>(
+            &mut parent_state,
+            Some(parent_state_root),
+            column_slot,
+            &chain.spec,
+        )?;
+
+        let proposers = state.get_beacon_proposer_indices(&chain.spec)?;
+        let proposer_index = *proposers
+            .get(column_slot.as_usize() % T::EthSpec::slots_per_epoch() as usize)
+            .ok_or_else(|| BeaconChainError::NoProposerForSlot(column_slot))?;
+
+        // Prime the proposer shuffling cache with the newly-learned value.
+        chain.beacon_proposer_cache.lock().insert(
+            column_epoch,
+            proposer_shuffling_root,
+            proposers,
+            state.fork(),
+        )?;
+        (proposer_index, state.fork())
+    };
+
+    // Signature verify the signed block header.
+    let signature_is_valid = {
+        let pubkey_cache = get_validator_pubkey_cache(chain)
+            .map_err(|_| GossipDataColumnError::PubkeyCacheTimeout)?;
+
+        let pubkey = pubkey_cache
+            .get(proposer_index)
+            .ok_or_else(|| GossipDataColumnError::UnknownValidator(proposer_index as u64))?;
+        let signed_block_header = &data_column.signed_block_header;
+        signed_block_header.verify_signature::<T::EthSpec>(
+            pubkey,
+            &fork,
+            chain.genesis_validators_root,
+            &chain.spec,
+        )
+    };
+
+    if !signature_is_valid {
+        return Err(GossipDataColumnError::ProposalSignatureInvalid);
+    }
+
+    let column_proposer_index = data_column.block_proposer_index();
+    if proposer_index != column_proposer_index as usize {
+        return Err(GossipDataColumnError::ProposerIndexMismatch {
+            sidecar: column_proposer_index as usize,
+            local: proposer_index,
+        });
+    }
+
+    Ok(())
+}
+
+fn verify_index_matches_subnet<E: EthSpec>(
+    data_column: &DataColumnSidecar<E>,
+    subnet: u64,
+    spec: &ChainSpec,
+) -> Result<(), GossipDataColumnError> {
+    let expected_subnet: u64 =
+        DataColumnSubnetId::from_column_index::<E>(data_column.index as usize, spec).into();
+    if expected_subnet != subnet {
+        return Err(GossipDataColumnError::InvalidSubnetId {
+            received: subnet,
+            expected: expected_subnet,
+        });
+    }
+    Ok(())
+}
+
+fn verify_slot_greater_than_latest_finalized_slot<T: BeaconChainTypes>(
+    chain: &BeaconChain<T>,
+    column_slot: Slot,
+) -> Result<(), GossipDataColumnError> {
+    let latest_finalized_slot = chain
+        .head()
+        .finalized_checkpoint()
+        .epoch
+        .start_slot(T::EthSpec::slots_per_epoch());
+    if column_slot <= latest_finalized_slot {
+        return Err(GossipDataColumnError::PastFinalizedSlot {
+            column_slot,
+            finalized_slot: latest_finalized_slot,
+        });
+    }
+    Ok(())
+}
+
+fn verify_sidecar_not_from_future_slot<T: BeaconChainTypes>(
+    chain: &BeaconChain<T>,
+    column_slot: Slot,
+) -> Result<(), GossipDataColumnError> {
+    let latest_permissible_slot = chain
+        .slot_clock
+        .now_with_future_tolerance(chain.spec.maximum_gossip_clock_disparity())
+        .ok_or(BeaconChainError::UnableToReadSlot)?;
+    if column_slot > latest_permissible_slot {
+        return Err(GossipDataColumnError::FutureSlot {
+            message_slot: column_slot,
+            latest_permissible_slot,
+        });
+    }
+    Ok(())
+}