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Add KZG commitment consistency check #6044

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Add KZG commitment consistency check #6044

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44ba3c4
Check for kzg commitments consistency with block for `RpcBlock`.
jimmygchen Jul 4, 2024
4859e84
Check for kzg commitments consistency when adding gossip data columns…
jimmygchen Jul 4, 2024
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29 changes: 26 additions & 3 deletions beacon_node/beacon_chain/src/block_verification_types.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ use crate::data_column_verification::{
use crate::eth1_finalization_cache::Eth1FinalizationData;
use crate::{get_block_root, GossipVerifiedBlock, PayloadVerificationOutcome};
use derivative::Derivative;
use itertools::Itertools;
use ssz_types::VariableList;
use state_processing::ConsensusContext;
use std::fmt::{Debug, Formatter};
Expand Down Expand Up @@ -162,10 +163,32 @@ impl<E: EthSpec> RpcBlock<E> {
) -> Result<Self, AvailabilityCheckError> {
let block_root = block_root.unwrap_or_else(|| get_block_root(&block));

if block.num_expected_blobs() > 0 && custody_columns.is_empty() {
// The number of required custody columns is out of scope here.
return Err(AvailabilityCheckError::MissingCustodyColumns);
let column_commitments = custody_columns
.iter()
.map(|c| c.as_data_column().kzg_commitments.clone())
.unique()
.at_most_one()
.map_err(|_| AvailabilityCheckError::KzgCommitmentsInconsistent)?;

if let (Some(column_commitments), Ok(block_commitments)) = (
column_commitments,
block.message().body().blob_kzg_commitments(),
) {
if column_commitments.len() != block_commitments.len() {
return Err(AvailabilityCheckError::KzgCommitmentListMismatch);
}
for (&column_commitment, &block_commitment) in
column_commitments.iter().zip(block_commitments.iter())
{
if column_commitment != block_commitment {
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I actually want to remove this check for blob sidecars since the inclusion proof should ensure that this never happens. Have you observed this inconsistency issue on devnets?

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Yeah I actually ran into a few KZG errors during sync.

I think you raised a good point and this PR shouldn't be required. The proper fix is to ensure that we verify the inclusion proof - I think we're missing this in sampling and by range rpc. I'll raise an issue.

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Raised issue #6111. Closing this one

return Err(AvailabilityCheckError::KzgCommitmentMismatch {
block_commitment,
blob_commitment: column_commitment,
});
}
}
}

// Treat empty data column lists as if they are missing.
let inner = if !custody_columns.is_empty() {
RpcBlockInner::BlockAndCustodyColumns(
Expand Down
7 changes: 7 additions & 0 deletions beacon_node/beacon_chain/src/data_availability_checker/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,15 @@ pub enum Error {
Kzg(KzgError),
KzgNotInitialized,
KzgVerificationFailed,
/// `KzgCommitment` for blob does not match `KzgCommitments` from the block.
KzgCommitmentMismatch {
blob_commitment: KzgCommitment,
block_commitment: KzgCommitment,
},
/// `KzgCommitments` from data column sidecars do not match `KzgCommitments` from the block.
KzgCommitmentListMismatch,
/// `KzgCommitments` are not identical for all sidecars for the same block.
KzgCommitmentsInconsistent,
UnableToDetermineImportRequirement,
Unexpected,
SszTypes(ssz_types::Error),
Expand Down Expand Up @@ -52,6 +57,8 @@ impl Error {
| Error::BlobIndexInvalid(_)
| Error::DataColumnIndexInvalid(_)
| Error::KzgCommitmentMismatch { .. }
| Error::KzgCommitmentListMismatch
| Error::KzgCommitmentsInconsistent
| Error::KzgVerificationFailed => ErrorCategory::Malicious,
}
}
Expand Down
87 changes: 75 additions & 12 deletions beacon_node/beacon_chain/src/data_availability_checker/overflow_lru_cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,13 @@ impl<E: EthSpec> PendingComponents<E> {
&mut self.verified_blobs
}

/// Returns a mutable reference to the cached data columns.
pub fn get_cached_data_columns_mut(
&mut self,
) -> &mut RuntimeVariableList<KzgVerifiedCustodyDataColumn<E>> {
&mut self.verified_data_columns
}

/// Checks if a blob exists at the given index in the cache.
///
/// Returns:
Expand Down Expand Up @@ -208,12 +215,26 @@ impl<E: EthSpec> PendingComponents<E> {
}

/// Merges a given set of data columns into the cache.
///
/// Data columns that don't match the new block's commitments are evicted.
/// NOTE: It is important that data columns are evicted instead of returning an
/// error on a mismatch, so invalid data columns don't prevent valid blocks from
/// getting inserted.
fn merge_data_columns<I: IntoIterator<Item = KzgVerifiedCustodyDataColumn<E>>>(
&mut self,
kzg_verified_data_columns: I,
) -> Result<(), AvailabilityCheckError> {
let maybe_block_commitments = self
.get_cached_block()
.as_ref()
.map(|b| b.get_commitments());

for data_column in kzg_verified_data_columns {
// TODO(das): Add equivalent checks for data columns if necessary
if let Some(ref block_commitments) = maybe_block_commitments {
if data_column.as_data_column().kzg_commitments != *block_commitments {
continue;
}
}
if !self.data_column_exists(data_column.index()) {
self.verified_data_columns.push(data_column)?;
}
Expand All @@ -224,10 +245,29 @@ impl<E: EthSpec> PendingComponents<E> {
/// Inserts a new block and revalidates the existing blobs against it.
///
/// Blobs that don't match the new block's commitments are evicted.
pub fn merge_block(&mut self, block: DietAvailabilityPendingExecutedBlock<E>) {
/// NOTE: It is important that blobs are evicted instead of returning an error on a mismatch,
/// so invalid blobs don't prevent valid blocks from getting inserted.
pub fn merge_block(
&mut self,
block: DietAvailabilityPendingExecutedBlock<E>,
block_import_requirement: &BlockImportRequirement,
spec: &ChainSpec,
) -> Result<(), AvailabilityCheckError> {
self.insert_block(block);
let reinsert = std::mem::take(self.get_cached_blobs_mut());
self.merge_blobs(reinsert);
match block_import_requirement {
BlockImportRequirement::AllBlobs => {
let reinsert = std::mem::take(self.get_cached_blobs_mut());
self.merge_blobs(reinsert);
}
BlockImportRequirement::CustodyColumns(_) => {
let reinsert = std::mem::replace(
self.get_cached_data_columns_mut(),
RuntimeVariableList::empty(spec.number_of_columns),
);
self.merge_data_columns(reinsert)?;
}
}
Ok(())
}

/// Checks if the block and all of its expected blobs or custody columns (post-PeerDAS) are
Expand Down Expand Up @@ -843,7 +883,13 @@ impl<T: BeaconChainTypes> OverflowLRUCache<T> {
let epoch = pending_components
.epoch()
.ok_or(AvailabilityCheckError::UnableToDetermineImportRequirement)?;
self.block_import_requirement_from_epoch(epoch)
}

fn block_import_requirement_from_epoch(
&self,
epoch: Epoch,
) -> Result<BlockImportRequirement, AvailabilityCheckError> {
let peer_das_enabled = self.spec.is_peer_das_enabled_for_epoch(epoch);
if peer_das_enabled {
Ok(BlockImportRequirement::CustodyColumns(
Expand Down Expand Up @@ -1033,11 +1079,16 @@ impl<T: BeaconChainTypes> OverflowLRUCache<T> {
.pop_pending_components(block_root, &self.overflow_store)?
.unwrap_or_else(|| PendingComponents::empty(block_root, &self.spec));

let block_import_requirement =
self.block_import_requirement_from_epoch(diet_executed_block.epoch())?;
// Merge in the block.
pending_components.merge_block(diet_executed_block);
pending_components.merge_block(
diet_executed_block,
&block_import_requirement,
&self.spec,
)?;

// Check if we have all components and entire set is consistent.
let block_import_requirement = self.block_import_requirement(&pending_components)?;
if pending_components.is_available(&block_import_requirement, &self.log) {
write_lock.put_pending_components(
block_root,
Expand Down Expand Up @@ -2407,7 +2458,9 @@ mod pending_components_tests {
let block_root = Hash256::zero();
let spec = E::default_spec();
let mut cache = <PendingComponents<E>>::empty(block_root, &spec);
cache.merge_block(block_commitments);
cache
.merge_block(block_commitments, &BlockImportRequirement::AllBlobs, &spec)
.unwrap();
cache.merge_blobs(random_blobs);
cache.merge_blobs(blobs);

Expand All @@ -2423,7 +2476,9 @@ mod pending_components_tests {
let spec = E::default_spec();
let mut cache = <PendingComponents<E>>::empty(block_root, &spec);
cache.merge_blobs(random_blobs);
cache.merge_block(block_commitments);
cache
.merge_block(block_commitments, &BlockImportRequirement::AllBlobs, &spec)
.unwrap();
cache.merge_blobs(blobs);

assert_cache_consistent(cache);
Expand All @@ -2440,7 +2495,9 @@ mod pending_components_tests {
let mut cache = <PendingComponents<E>>::empty(block_root, &spec);
cache.merge_blobs(random_blobs);
cache.merge_blobs(blobs);
cache.merge_block(block_commitments);
cache
.merge_block(block_commitments, &BlockImportRequirement::AllBlobs, &spec)
.unwrap();

assert_empty_blob_cache(cache);
}
Expand All @@ -2454,7 +2511,9 @@ mod pending_components_tests {
let block_root = Hash256::zero();
let spec = E::default_spec();
let mut cache = <PendingComponents<E>>::empty(block_root, &spec);
cache.merge_block(block_commitments);
cache
.merge_block(block_commitments, &BlockImportRequirement::AllBlobs, &spec)
.unwrap();
cache.merge_blobs(blobs);
cache.merge_blobs(random_blobs);

Expand All @@ -2471,7 +2530,9 @@ mod pending_components_tests {
let spec = E::default_spec();
let mut cache = <PendingComponents<E>>::empty(block_root, &spec);
cache.merge_blobs(blobs);
cache.merge_block(block_commitments);
cache
.merge_block(block_commitments, &BlockImportRequirement::AllBlobs, &spec)
.unwrap();
cache.merge_blobs(random_blobs);

assert_cache_consistent(cache);
Expand All @@ -2488,7 +2549,9 @@ mod pending_components_tests {
let mut cache = <PendingComponents<E>>::empty(block_root, &spec);
cache.merge_blobs(blobs);
cache.merge_blobs(random_blobs);
cache.merge_block(block_commitments);
cache
.merge_block(block_commitments, &BlockImportRequirement::AllBlobs, &spec)
.unwrap();

assert_cache_consistent(cache);
}
Expand Down
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