feat(protocol): fix issues in AssignmentHook (#15486)

Co-authored-by: David <[email protected]>
Co-authored-by: Daniel Wang <[email protected]>
Co-authored-by: Daniel Wang <[email protected]>

packages/protocol/contracts/L1/ITaikoL1.sol

@@ -43,4 +43,8 @@ interface ITaikoL1 {
     /// @notice Verifies up to a certain number of blocks.
     /// @param maxBlocksToVerify Max number of blocks to verify.
     function verifyBlocks(uint64 maxBlocksToVerify) external;
+
+    /// @notice Gets the configuration of the TaikoL1 contract.
+    /// @return Config struct containing configuration parameters.
+    function getConfig() external view returns (TaikoData.Config memory);
 }

packages/protocol/contracts/L1/TaikoL1.sol

@@ -203,9 +203,8 @@ contract TaikoL1 is
         return ITierProvider(resolve("tier_provider", false)).getMinTier(rand);
     }
 
-    /// @notice Gets the configuration of the TaikoL1 contract.
-    /// @return Config struct containing configuration parameters.
-    function getConfig() public view virtual returns (TaikoData.Config memory) {
+    /// @inheritdoc ITaikoL1
+    function getConfig() public view virtual override returns (TaikoData.Config memory) {
         // All hard-coded configurations:
         // - treasury: the actual TaikoL2 address.
         // - blockMaxTxs: 150 (limited by the PSE zkEVM circuits)

packages/protocol/contracts/L1/hooks/AssignmentHook.sol

@@ -18,7 +18,7 @@ import "lib/openzeppelin-contracts/contracts/token/ERC20/IERC20.sol";
 import "lib/openzeppelin-contracts/contracts/token/ERC20/utils/SafeERC20.sol";
 import "../../common/EssentialContract.sol";
 import "../../libs/LibAddress.sol";
-import "../TaikoData.sol";
+import "../ITaikoL1.sol";
 import "./IHook.sol";
 
 /// @title AssignmentHook
@@ -39,7 +39,7 @@ contract AssignmentHook is EssentialContract, IHook {
 
     struct Input {
         ProverAssignment assignment;
-        uint256 tip;
+        uint256 tip; // A tip to L1 block builder
     }
 
     // Max gas paying the prover. This should be large enough to prevent the
@@ -70,6 +70,11 @@ contract AssignmentHook is EssentialContract, IHook {
         nonReentrant
         onlyFromNamed("taiko")
     {
+        // Note that
+        // - 'msg.sender' is the TaikoL1 contract address
+        // - 'block.coinbase' is the L1 block builder
+        // - 'meta.coinbase' is the L2 block proposer
+
         Input memory input = abi.decode(data, (Input));
         ProverAssignment memory assignment = input.assignment;
 
@@ -85,15 +90,16 @@ contract AssignmentHook is EssentialContract, IHook {
 
         // Hash the assignment with the blobHash, this hash will be signed by
         // the prover, therefore, we add a string as a prefix.
-        bytes32 hash = hashAssignment(assignment, msg.sender, meta.blobHash);
+        address taikoL1Address = msg.sender;
+        bytes32 hash = hashAssignment(assignment, taikoL1Address, meta.blobHash);
 
         if (!blk.assignedProver.isValidSignature(hash, assignment.signature)) {
             revert HOOK_ASSIGNMENT_INVALID_SIG();
         }
 
         // Send the liveness bond to the Taiko contract
         IERC20 tko = IERC20(resolve("taiko_token", false));
-        tko.transferFrom(blk.assignedProver, msg.sender, blk.livenessBond);
+        tko.transferFrom(blk.assignedProver, taikoL1Address, blk.livenessBond);
 
         // Find the prover fee using the minimal tier
         uint256 proverFee = _getProverFee(assignment.tierFees, meta.minTier);
@@ -102,12 +108,13 @@ contract AssignmentHook is EssentialContract, IHook {
         // Ether or ERC20 tokens.
         uint256 refund;
         if (assignment.feeToken == address(0)) {
-            if (msg.value < proverFee + input.tip) {
+            uint256 totalFee = proverFee + input.tip;
+            if (msg.value < totalFee) {
                 revert HOOK_ASSIGNMENT_INSUFFICIENT_FEE();
             }
 
             unchecked {
-                refund = msg.value - proverFee - input.tip;
+                refund = msg.value - totalFee;
             }
 
             // Paying Ether
@@ -120,7 +127,9 @@ contract AssignmentHook is EssentialContract, IHook {
                 refund = msg.value - input.tip;
             }
             // Paying ERC20 tokens
-            IERC20(assignment.feeToken).safeTransferFrom(msg.sender, blk.assignedProver, proverFee);
+            IERC20(assignment.feeToken).safeTransferFrom(
+                meta.coinbase, blk.assignedProver, proverFee
+            );
         }
 
         // block.coinbase can be address(0) in tests
@@ -129,25 +138,29 @@ contract AssignmentHook is EssentialContract, IHook {
         }
 
         if (refund != 0) {
-            msg.sender.sendEther(refund);
+            // Send all remaininger Ether back to TaikoL1 contract
+            taikoL1Address.sendEther(refund);
         }
 
         emit BlockAssigned(blk.assignedProver, meta, assignment);
     }
 
     function hashAssignment(
         ProverAssignment memory assignment,
-        address taikoAddress,
+        address taikoL1Address,
         bytes32 blobHash
     )
         public
-        pure
+        view
         returns (bytes32)
     {
         return keccak256(
             abi.encode(
                 "PROVER_ASSIGNMENT",
-                taikoAddress,
+                ITaikoL1(taikoL1Address).getConfig().chainId,
+                taikoL1Address,
+                address(this),
+                assignment.metaHash,
                 blobHash,
                 assignment.feeToken,
                 assignment.expiry,

packages/protocol/contracts/L1/libs/LibProposing.sol

@@ -261,8 +261,10 @@ library LibProposing {
             }
 
             // Check that after hooks, the Taiko Token balance of this contract
-            // have increased by at least config.livenessBond
-            if (tko.balanceOf(address(this)) < tkoBalance + config.livenessBond) {
+            // have increased by the same amount as config.livenessBond (to prevent)
+            // multiple draining payments by a malicious proposer nesting the same
+            // hook.
+            if (tko.balanceOf(address(this)) != tkoBalance + config.livenessBond) {
                 revert L1_LIVENESS_BOND_NOT_RECEIVED();
             }
         }