fix: reject block proposals in poisoned slots

Author: alexghr

yarn-project/validator-client/src/proposal_handler.ts

@@ -58,6 +58,8 @@ export type BlockProposalValidationFailureReason =
   | 'failed_txs'
   | 'initial_state_mismatch'
   | 'timeout'
+  | 'block_proposal_beyond_checkpoint'
+  | 'checkpoint_proposal_equivocation'
   | 'unknown_error';
 
 type ReexecuteTransactionsResult = {
@@ -145,6 +147,10 @@ type CheckpointComputationResult =
   | { checkpointNumber: CheckpointNumber; reason?: undefined }
   | { checkpointNumber?: undefined; reason: 'invalid_proposal' | 'global_variables_mismatch' };
 
+type BlockProposalSlotValidationResult =
+  | { isValid: true }
+  | { isValid: false; reason: 'block_proposal_beyond_checkpoint' | 'checkpoint_proposal_equivocation' };
+
 /** Handles block and checkpoint proposals for both validator and non-validator nodes. */
 export class ProposalHandler {
   public readonly tracer: Tracer;
@@ -163,6 +169,9 @@ export class ProposalHandler {
   /** Returns current validator addresses for own-proposal detection. Set via register(). */
   private getOwnValidatorAddresses?: () => string[];
 
+  /** P2P proposal pool access for deciding when retained proposals should block archiver processing. */
+  private p2pClient?: Pick<P2P, 'getProposalsForSlot'>;
+
   private checkpointProposalValidationFailureCallback?: CheckpointProposalValidationFailureCallback;
 
   constructor(
@@ -212,6 +221,7 @@ export class ProposalHandler {
 
   /**
    * Registers handlers for block and checkpoint proposals on the p2p client.
+   * Records the p2p client so validation can inspect retained proposals.
    * Block proposals are registered for non-validator nodes (validators register their own enhanced handler).
    * The all-nodes checkpoint proposal handler is always registered for validation, caching, and pipelining.
    * @param archiver - Archiver reference for setting proposed checkpoints (pipelining)
@@ -223,6 +233,7 @@ export class ProposalHandler {
     archiver?: Pick<Archiver, 'addProposedCheckpoint' | 'getL1Constants'>,
     getOwnValidatorAddresses?: () => string[],
   ): ProposalHandler {
+    this.p2pClient = p2pClient;
     this.archiver = archiver;
     this.getOwnValidatorAddresses = getOwnValidatorAddresses;
 
@@ -361,6 +372,16 @@ export class ProposalHandler {
       return { isValid: false, reason: 'invalid_proposal' };
     }
 
+    const retainedSlotValidation = await this.validateNewBlockInSlot(proposal);
+    if (!retainedSlotValidation.isValid) {
+      this.log.info(`Block proposal conflicts with retained proposals, skipping archiver processing`, {
+        ...proposalInfo,
+        indexWithinCheckpoint: proposal.indexWithinCheckpoint,
+        reason: retainedSlotValidation.reason,
+      });
+      return { isValid: false, blockNumber: proposal.blockNumber, reason: retainedSlotValidation.reason };
+    }
+
     // Ensure the block source is synced before checking for existing blocks,
     // since a proposed checkpoint prune may remove blocks we'd otherwise find.
     // This affects mostly the block_number_already_exists check, since a pending
@@ -499,6 +520,26 @@ export class ProposalHandler {
     return { isValid: true, blockNumber, reexecutionResult };
   }
 
+  private async validateNewBlockInSlot(blockProposal: BlockProposal): Promise<BlockProposalSlotValidationResult> {
+    if (!this.p2pClient) {
+      return { isValid: true };
+    }
+
+    const { blockProposals, checkpointProposals } = await this.p2pClient.getProposalsForSlot(blockProposal.slotNumber);
+
+    if (checkpointProposals.length === 0) {
+      return { isValid: true };
+    } else if (checkpointProposals.length > 1) {
+      return { isValid: false, reason: 'checkpoint_proposal_equivocation' };
+    } else {
+      const checkpointProposal = checkpointProposals[0];
+      const terminalBlock = blockProposals.find(block => block.archive.equals(checkpointProposal.archive));
+      return terminalBlock !== undefined && blockProposal.indexWithinCheckpoint > terminalBlock.indexWithinCheckpoint
+        ? { isValid: false, reason: 'block_proposal_beyond_checkpoint' }
+        : { isValid: true };
+    }
+  }
+
   private async getParentBlock(proposal: BlockProposal): Promise<'genesis' | BlockData | undefined> {
     const parentArchive = proposal.blockHeader.lastArchive.root;
     const config = this.checkpointsBuilder.getConfig();

yarn-project/validator-client/src/validator.test.ts

@@ -117,6 +117,7 @@ describe('ValidatorClient', () => {
     p2pClient.getCheckpointAttestationsForSlot.mockImplementation(() => Promise.resolve([]));
     p2pClient.handleAuthRequestFromPeer.mockResolvedValue(StatusMessage.random());
     p2pClient.broadcastCheckpointAttestations.mockResolvedValue();
+    p2pClient.getProposalsForSlot.mockResolvedValue({ blockProposals: [], checkpointProposals: [] });
     checkpointsBuilder = mock<FullNodeCheckpointsBuilder>();
     checkpointsBuilder.getConfig.mockReturnValue({
       l1GenesisTime: 1n,
@@ -529,6 +530,121 @@ describe('ValidatorClient', () => {
       expect(isValid).toBe(true);
     });
 
+    it('does not push a block proposal beyond a retained checkpoint terminal block to the archiver', async () => {
+      validatorClient.updateConfig({ skipPushProposedBlocksToArchiver: false });
+      validatorClient.getProposalHandler().register(p2pClient, true);
+
+      const signer = Secp256k1Signer.random();
+      const emptyInHash = computeInHashFromL1ToL2Messages([]);
+      const checkpointProposal = await makeCheckpointProposal({
+        signer,
+        checkpointHeader: makeCheckpointHeader(1, { slotNumber: proposal.slotNumber, inHash: emptyInHash }),
+        archiveRoot: Fr.random(),
+        lastBlock: {
+          blockHeader: makeBlockHeader(1, { blockNumber, slotNumber: proposal.slotNumber }),
+          indexWithinCheckpoint: IndexWithinCheckpoint(0),
+          txHashes: proposal.txHashes,
+        },
+      });
+      const terminalBlock = checkpointProposal.getBlockProposal()!;
+
+      const terminalGlobals = terminalBlock.blockHeader.globalVariables;
+      const laterBlockHeader = makeBlockHeader(2, {
+        lastArchive: new AppendOnlyTreeSnapshot(terminalBlock.archive, terminalBlock.blockNumber),
+        blockNumber: BlockNumber(terminalBlock.blockNumber + 1),
+        slotNumber: proposal.slotNumber,
+        chainId: terminalGlobals.chainId,
+        version: terminalGlobals.version,
+        timestamp: terminalGlobals.timestamp,
+        coinbase: terminalGlobals.coinbase,
+        feeRecipient: terminalGlobals.feeRecipient,
+        gasFees: terminalGlobals.gasFees,
+      });
+      const laterBlock = await makeBlockProposal({
+        signer,
+        blockHeader: laterBlockHeader,
+        indexWithinCheckpoint: IndexWithinCheckpoint(1),
+        inHash: emptyInHash,
+        archiveRoot: Fr.random(),
+      });
+
+      epochCache.getProposerAttesterAddressInSlot.mockResolvedValue(signer.address);
+      p2pClient.getProposalsForSlot.mockResolvedValue({
+        blockProposals: [terminalBlock, laterBlock],
+        checkpointProposals: [checkpointProposal.toCore()],
+      });
+
+      const terminalBlockData = {
+        header: terminalBlock.blockHeader,
+        archive: new AppendOnlyTreeSnapshot(terminalBlock.archive, terminalBlock.blockNumber),
+        blockHash: BlockHash.random(),
+        checkpointNumber: CheckpointNumber(1),
+        indexWithinCheckpoint: terminalBlock.indexWithinCheckpoint,
+      } as unknown as BlockData;
+      blockSource.getBlockData.mockImplementation(query =>
+        Promise.resolve('number' in query ? undefined : terminalBlockData),
+      );
+
+      const blockAddedIfProcessed = {
+        ...blockBuildResult.block,
+        header: laterBlock.blockHeader,
+        body: { txEffects: times(laterBlock.txHashes.length, () => TxEffect.empty()) },
+        archive: new AppendOnlyTreeSnapshot(laterBlock.archive, laterBlock.blockNumber),
+        checkpointNumber: CheckpointNumber(1),
+        indexWithinCheckpoint: laterBlock.indexWithinCheckpoint,
+      } as unknown as L2Block;
+      mockCheckpointBuilder.buildBlock.mockResolvedValue({
+        ...blockBuildResult,
+        block: blockAddedIfProcessed,
+        numTxs: laterBlock.txHashes.length,
+      });
+      worldState.fork.mockResolvedValue({
+        close: () => Promise.resolve(),
+        [Symbol.asyncDispose]: () => Promise.resolve(),
+        getTreeInfo: () => Promise.resolve({ root: laterBlock.blockHeader.lastArchive.root.toBuffer() }),
+      } as never);
+
+      const result = await validatorClient.getProposalHandler().handleBlockProposal(laterBlock, sender, true);
+
+      expect(result).toMatchObject({ isValid: false, reason: 'block_proposal_beyond_checkpoint' });
+      expect(blockSource.addBlock).not.toHaveBeenCalled();
+    });
+
+    it('does not push a block proposal to the archiver when retained checkpoint proposals equivocate', async () => {
+      validatorClient.updateConfig({ skipPushProposedBlocksToArchiver: false });
+      validatorClient.getProposalHandler().register(p2pClient, true);
+
+      const emptyInHash = computeInHashFromL1ToL2Messages([]);
+      const checkpointProposal = await makeCheckpointProposal({
+        checkpointHeader: makeCheckpointHeader(1, { slotNumber: proposal.slotNumber, inHash: emptyInHash }),
+        archiveRoot: Fr.random(),
+        lastBlock: {
+          blockHeader: makeBlockHeader(1, { blockNumber, slotNumber: proposal.slotNumber }),
+          indexWithinCheckpoint: IndexWithinCheckpoint(0),
+          txHashes: proposal.txHashes,
+        },
+      });
+      const equivocatedCheckpointProposal = await makeCheckpointProposal({
+        checkpointHeader: makeCheckpointHeader(1, { slotNumber: proposal.slotNumber, inHash: emptyInHash }),
+        archiveRoot: Fr.random(),
+        lastBlock: {
+          blockHeader: makeBlockHeader(1, { blockNumber, slotNumber: proposal.slotNumber }),
+          indexWithinCheckpoint: IndexWithinCheckpoint(0),
+          txHashes: proposal.txHashes,
+        },
+      });
+
+      p2pClient.getProposalsForSlot.mockResolvedValue({
+        blockProposals: [proposal],
+        checkpointProposals: [checkpointProposal.toCore(), equivocatedCheckpointProposal.toCore()],
+      });
+
+      const result = await validatorClient.getProposalHandler().handleBlockProposal(proposal, sender, true);
+
+      expect(result).toMatchObject({ isValid: false, reason: 'checkpoint_proposal_equivocation' });
+      expect(blockSource.addBlock).not.toHaveBeenCalled();
+    });
+
     it('uses the next wall-clock slot as the tx collection deadline for pipelined proposals', async () => {
       const pipelineOffsetInSlots = 1;
       epochCache.isProposerPipeliningEnabled.mockReturnValue(true);