validate EL block hash in EL simulation (#4420)

When simulating EL with `--optimistic` flag, perform block hash check.

Author: etan-status

beacon_chain/gossip_processing/block_processor.nim

@@ -374,14 +374,28 @@ proc storeBlock*(
     self.consensusManager.quarantine[].addUnviable(signedBlock.root)
     return err((VerifierError.UnviableFork, ProcessingStatus.completed))
 
-  if NewPayloadStatus.noResponse == payloadStatus and not self[].optimistic:
-    # Disallow the `MissingParent` from leaking to the sync/request managers
-    # as it will be descored. However sync and request managers interact via
-    # `processBlock` (indirectly). `validator_duties` does call `storeBlock`
-    # directly, so is exposed to this, but only cares about whether there is
-    # an error or not.
-    return err((
-      VerifierError.MissingParent, ProcessingStatus.notCompleted))
+  if NewPayloadStatus.noResponse == payloadStatus:
+    if not self[].optimistic:
+      # Disallow the `MissingParent` from leaking to the sync/request managers
+      # as it will be descored. However sync and request managers interact via
+      # `processBlock` (indirectly). `validator_duties` does call `storeBlock`
+      # directly, so is exposed to this, but only cares about whether there is
+      # an error or not.
+      return err((
+        VerifierError.MissingParent, ProcessingStatus.notCompleted))
+
+    # Client software MUST validate blockHash value as being equivalent to
+    # Keccak256(RLP(ExecutionBlockHeader))
+    # https://github.com/ethereum/execution-apis/blob/v1.0.0-beta.1/src/engine/specification.md#specification
+    when typeof(signedBlock).toFork() >= BeaconBlockFork.Bellatrix:
+      template payload(): auto = signedBlock.message.body.execution_payload
+      if payload.block_hash != payload.compute_execution_block_hash():
+        debug "EL block hash validation failed", execution_payload = payload
+        doAssert strictVerification notin dag.updateFlags
+        self.consensusManager.quarantine[].addUnviable(signedBlock.root)
+        return err((VerifierError.UnviableFork, ProcessingStatus.completed))
+    else:
+      discard
 
   # We'll also remove the block as an orphan: it's unlikely the parent is
   # missing if we get this far - should that be the case, the block will

beacon_chain/spec/helpers.nim

@@ -372,6 +372,19 @@ func compute_timestamp_at_slot*(state: ForkyBeaconState, slot: Slot): uint64 =
   let slots_since_genesis = slot - GENESIS_SLOT
   state.genesis_time + slots_since_genesis * SECONDS_PER_SLOT
 
+proc computeTransactionsTrieRoot*(
+    payload: bellatrix.ExecutionPayload | capella.ExecutionPayload): Hash256 =
+  if payload.transactions.len == 0:
+    return EMPTY_ROOT_HASH
+
+  var tr = initHexaryTrie(newMemoryDB())
+  for i, transaction in payload.transactions:
+    try:
+      tr.put(rlp.encode(i), distinctBase(transaction))  # Already RLP encoded
+    except RlpError as exc:
+      doAssert false, "HexaryTrie.put failed: " & $exc.msg
+  tr.rootHash()
+
 func gweiToWei*(gwei: Gwei): UInt256 =
   gwei.u256 * 1_000_000_000.u256
 
@@ -397,18 +410,15 @@ proc computeWithdrawalsTrieRoot*(
       doAssert false, "HexaryTrie.put failed: " & $exc.msg
   tr.rootHash()
 
-proc emptyPayloadToBlockHeader*(
+proc payloadToBlockHeader*(
     payload: bellatrix.ExecutionPayload | capella.ExecutionPayload
 ): ExecutionBlockHeader =
   static:  # `GasInt` is signed. We only use it for hashing.
     doAssert sizeof(GasInt) == sizeof(payload.gas_limit)
     doAssert sizeof(GasInt) == sizeof(payload.gas_used)
 
-  ## This function assumes that the payload is empty!
-  doAssert payload.transactions.len == 0
-
   let
-    txRoot = EMPTY_ROOT_HASH
+    txRoot = payload.computeTransactionsTrieRoot()
     withdrawalsRoot =
       when payload is bellatrix.ExecutionPayload:
         none(Hash256)
@@ -434,7 +444,12 @@ proc emptyPayloadToBlockHeader*(
     fee            : some payload.base_fee_per_gas,
     withdrawalsRoot: withdrawalsRoot)
 
-func build_empty_execution_payload*(
+proc compute_execution_block_hash*(
+    payload: bellatrix.ExecutionPayload | capella.ExecutionPayload
+): Eth2Digest =
+  rlpHash payloadToBlockHeader(payload)
+
+proc build_empty_execution_payload*(
     state: bellatrix.BeaconState,
     feeRecipient: Eth1Address): bellatrix.ExecutionPayload =
   ## Assuming a pre-state of the same slot, build a valid ExecutionPayload
@@ -459,7 +474,7 @@ func build_empty_execution_payload*(
     timestamp: timestamp,
     base_fee_per_gas: base_fee)
 
-  payload.block_hash = rlpHash emptyPayloadToBlockHeader(payload)
+  payload.block_hash = payload.compute_execution_block_hash()
 
   payload
 
@@ -491,6 +506,6 @@ proc build_empty_execution_payload*(
   for withdrawal in expectedWithdrawals:
     doAssert payload.withdrawals.add withdrawal
 
-  payload.block_hash = rlpHash emptyPayloadToBlockHeader(payload)
+  payload.block_hash = payload.compute_execution_block_hash()
 
   payload

tests/test_helpers.nim

@@ -96,7 +96,7 @@ suite "Spec helpers":
       for i, withdrawal in withdrawals:
         check payload.withdrawals[i] == withdrawal
 
-      let elHeader = emptyPayloadToBlockHeader(payload)
+      let elHeader = payloadToBlockHeader(payload)
       check elHeader.withdrawalsRoot.isSome
       if withdrawals.len == 0:
         check elHeader.withdrawalsRoot.get == EMPTY_ROOT_HASH

tests/testblockutil.nim

@@ -81,7 +81,7 @@ func signBlock(
 from ../beacon_chain/spec/datatypes/capella import
   BeaconState, ExecutionPayload, SignedBLSToExecutionChangeList
 
-func build_empty_merge_execution_payload(state: bellatrix.BeaconState):
+proc build_empty_merge_execution_payload(state: bellatrix.BeaconState):
     bellatrix.ExecutionPayload =
   ## Assuming a pre-state of the same slot, build a valid ExecutionPayload
   ## without any transactions from a non-merged block.
@@ -104,7 +104,7 @@ func build_empty_merge_execution_payload(state: bellatrix.BeaconState):
     timestamp: timestamp,
     base_fee_per_gas: EIP1559_INITIAL_BASE_FEE)
 
-  payload.block_hash = rlpHash emptyPayloadToBlockHeader(payload)
+  payload.block_hash = rlpHash payloadToBlockHeader(payload)
 
   payload
 
@@ -131,7 +131,7 @@ proc build_empty_merge_execution_payload(state: capella.BeaconState):
     timestamp: timestamp,
     base_fee_per_gas: EIP1559_INITIAL_BASE_FEE)
 
-  payload.block_hash = rlpHash emptyPayloadToBlockHeader(payload)
+  payload.block_hash = rlpHash payloadToBlockHeader(payload)
 
   payload