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OpenSea SeaPort contest details

• Total Prize Pool: $100,500 USDC
  • HM awards: $85,000 USDC
  • QA report awards: $8,500 USDC
  • Gas report awards: $5,000 USDC
  • Judge + presort awards: $15,000 USDC
  • Scout awards: $500 USDC
• Join C4 Discord to register
• Submit findings using the C4 form
• Read our guidelines for more details
• Starts January 13, 2023 20:00 UTC
• Ends January 23, 2023 20:00 UTC

IMPORTANT NOTE: Unlike most public Code4rena contests, prior to receiving payment from this contest you MUST become a Certified Warden (successfully complete KYC). You do not have to complete this process before competing or submitting bugs. You must have started this process within 48 hours after contest close, i.e. by January 18, 2023 at 20:00 UTC in order to receive payment.

C4udit / Publicly Known Issues

The C4audit output for the contest can be found here within an hour of contest opening.

Note for C4 wardens: Anything included in the C4udit output is considered a publicly known issue and is ineligible for awards.

• Cross-domain reentrancy between zones, contract offerers, token contracts, distinct instances of Seaport or other marketplaces, or other external contracts, or view-only reentrancy on functions such as getOrderStatus or getContractOffererNonce, is "publicly known"
• Lack of ERC721 safeTransferFrom usage in the transfer helper and on conduits is "publicly known"
• interaction with non-compliant or malicious ERC20/ERC721/ERC1155 implementations not considered in scope
• also see Seaport 1.1 out of scope / known limitations section: https://github.com/code-423n4/2022-05-opensea-seaport#out-of-scope

Cloning the repo

Please note that the contest's code is hosted on an external repo. To fetch it, use one of the following methods:

• Cloning using SSH:

git clone --recurse-submodules [email protected]:code-423n4/2023-01-opensea.git

• Cloning using HTTPS:

git clone --recurse-submodules https://github.com/code-423n4/2023-01-opensea.git

• Getting the submodules if cloning was done without --recurse-submodules:

git submodule update --init --recursive

Overview

Seaport v1.2 builds on Seaport v1.1 in a (mostly) backwards-compatible fashion, but includes a few new features and performs further optimizations on the codebase.

Contributions are welcome and encouraged; if you make any findings, we encourage you to open PRs (you will likely want to wait to make your findings public until the competition has concluded) and to add yourself as a contributor to the repo.

Gas optimizations that do not otherwise modify behavior or adversely impact safety are also welcome and encouraged. Any optimizations should be supported by an associated gas profile report (e.g. run yarn profile). Also, please do not submit optimizations for any of the reference contracts in reference/ or test contracts in contracts/test/ and test/foundry/, though informational findings to improve readability or cover missing test cases are more than welcome.

Scope

• contracts/Seaport.sol
• contracts/lib/*
• contracts/helpers/PointerLibraries.sol
• contracts/interfaces/*
• contracts/conduit/* (with the assumption that only Seaport v1.2 will be added as a channel)
• reference/* (only considered for informational issues)

Scope table

File	blank	comment	code
seaport/contracts/helpers/PointerLibraries.sol	337	344	2412
seaport/contracts/lib/ConsiderationDecoder.sol	156	498	650
seaport/contracts/lib/BasicOrderFulfiller.sol	138	407	574
seaport/contracts/lib/OrderValidator.sol	118	282	506
seaport/contracts/lib/OrderCombiner.sol	118	432	499
seaport/contracts/lib/TokenTransferrer.sol	86	269	477
seaport/contracts/lib/ConsiderationConstants.sol	131	491	428
seaport/contracts/lib/FulfillmentApplier.sol	92	236	412
seaport/contracts/lib/ConsiderationStructs.sol	51	111	380
seaport/contracts/lib/Executor.sol	61	254	345
seaport/contracts/lib/ConsiderationEncoder.sol	108	255	332
seaport/contracts/lib/Consideration.sol	24	485	269
seaport/contracts/lib/ConsiderationErrors.sol	75	307	249
seaport/contracts/lib/OrderFulfiller.sol	48	157	213
seaport/contracts/conduit/ConduitController.sol	70	223	211
seaport/contracts/lib/SignatureVerification.sol	41	104	178
seaport/contracts/lib/CriteriaResolution.sol	46	111	161
seaport/contracts/lib/GettersAndDerivers.sol	64	147	158
seaport/contracts/lib/ConsiderationBase.sol	39	87	154
seaport/contracts/lib/Verifiers.sol	33	103	136
seaport/contracts/lib/ZoneInteraction.sol	23	76	118
seaport/contracts/lib/TypehashDirectory.sol	24	54	105
seaport/contracts/conduit/Conduit.sol	31	119	97
seaport/contracts/interfaces/ConsiderationInterface.sol	17	347	94
seaport/contracts/interfaces/SeaportInterface.sol	17	346	94
seaport/contracts/lib/TokenTransferrerConstants.sol	23	73	94
seaport/contracts/lib/Assertions.sol	16	74	86
seaport/contracts/lib/AmountDeriver.sol	16	89	78
seaport/contracts/interfaces/ConduitControllerInterface.sol	28	197	71
seaport/contracts/lib/LowLevelHelpers.sol	10	55	58
seaport/contracts/lib/ConsiderationEnums.sol	43	49	54
seaport/contracts/interfaces/ConsiderationEventsAndErrors.sol	24	140	46
seaport/contracts/interfaces/ContractOffererInterface.sol	6	2	37
seaport/contracts/interfaces/TransferHelperErrors.sol	10	44	31
seaport/contracts/lib/CounterManager.sol	13	38	29
seaport/contracts/lib/ReentrancyGuard.sol	10	40	29
seaport/contracts/interfaces/TokenTransferrerErrors.sol	8	61	28
seaport/contracts/interfaces/AbridgedTokenInterfaces.sol	8	1	27
seaport/contracts/interfaces/ConduitInterface.sol	10	63	23
seaport/contracts/interfaces/ImmutableCreate2FactoryInterface.sol	4	74	18
seaport/contracts/conduit/lib/ConduitStructs.sol	3	1	17
seaport/contracts/Seaport.sol	4	101	15
seaport/contracts/interfaces/CriteriaResolutionErrors.sol	8	48	14
seaport/contracts/conduit/lib/ConduitConstants.sol	2	6	10
seaport/contracts/interfaces/FulfillmentApplicationErrors.sol	5	30	10
seaport/contracts/interfaces/TransferHelperInterface.sol	2	7	10
seaport/contracts/interfaces/IERC721Receiver.sol	1	1	9
seaport/contracts/conduit/lib/ConduitEnums.sol	1	1	7
seaport/contracts/interfaces/EIP1271Interface.sol	1	1	7
seaport/contracts/interfaces/SignatureVerificationErrors.sol	4	25	7
seaport/contracts/interfaces/ZoneInterface.sol	2	1	7
seaport/contracts/interfaces/ZoneInteractionErrors.sol	2	22	5
seaport/contracts/interfaces/AmountDerivationErrors.sol	1	10	4
seaport/contracts/interfaces/ReentrancyErrors.sol	1	10	4
SUM:	2214	7509	10087

Out of scope

• contracts/test/*
• contracts/zones/*
• test/*
• contracts/helpers/TransferHelper.sol
• contracts/helpers/TransferHelperStructs.sol
• gas optimizations not considered for reference contracts and constructor logic
• known gas optimizations from last contest which weren't implemented (lots of those concerning the conduit controller which is out of scope for gas optimizations due to the code being highly sensitive)

Additional Context

Seaport v1.2 builds on Seaport v1.1 with the following new characteristics:

• Contract orders do not have a signature, and instead are generated at the time of fulfillment by the contract order's offerer upon a stateful call to generateOrder from Seaport. The generated order must adhere to the requirements laid out by the fulfiller, namely that all of the designated offer item amounts, or greater, are returned as the offer and that all of the designated consideration item amounts, or less, are returned as the consideration. Seaport will also make a stateful call to ratifyOrder on the contract offerer after all transfers have been completed and must receive back the correct magic value. See the contract offerer interface for more details.
• Bulk signatures allow for signing multiple orders at once, and are fulfilled by providing the bulk signature, an index of the order being fulfilled, and a merkle proof that the order at the given index is part of the bulk signature payload. Powers of two between 2^1 and 2^24 are supported as payload sizes. If a signature is a valid size for bulk signatures, Seaport will attempt to verify it as such, falling back to standard EIP-1271 if it fails.
• Zone calls now occur after all transfers have occurred and use a single stateful validateOrder endpoint and must receive back the correct magic value for restricted orders to be considered valid. See the zone interface and the ZoneParameters struct for more details.
• Contract orders and orders being matched may designate native tokens (e.g. Ether) as offer items, and may pay provide said Ether to Seaport during fulfillment for use by the fulfiller. Any unspent native tokens will be returned to the caller.
• The OrderValidated event now emits the full OrderParameters struct as an argument, and a new OrdersMatched event is emitted when matching orders. A recipient is also supplied (or inferred) as an argument when matching orders, and will be reflected in the respective OrderFulfilled` event — this recipient will receive any unspent offer item amounts after all supplied fulfillments have been applied. Fulfillments will also now skip out-of-range items.
• Custom ABI encoding and decoding has been employed, generated by the abi-lity codegen tool, and many other optimizations have been implemented throughout.

For more information on Seaport in general, see the docs.

Scoping Details

- If you have a public code repo, please share it here: https://github.com/ProjectOpenSea/seaport/tree/seaport-1.2-code4rena-competition
- How many contracts are in scope?: ~30 core contracts along with a similar # of "reference" contracts
- Total SLoC for these contracts?: ~30k
- How many external imports are there?: n/a
- How many separate interfaces and struct definitions are there for the contracts within scope?: ~30
- Does most of your code generally use composition or inheritance?: inheritance
- How many external calls?: ~10 different flavors of external call
- What is the overall line coverage percentage provided by your tests?: >90%
- Is there a need to understand a separate part of the codebase / get context in order to audit this part of the protocol?: no
- Please describe required context: n/a
- Does it use an oracle?: no
- Does the token conform to the ERC20 standard?: n/a
- Are there any novel or unique curve logic or mathematical models?: n/a
- Does it use a timelock function?: no
- Is it an NFT?: no
- Does it have an AMM?: no
- Is it a fork of a popular project?: builds on Seaport v1.1
- Does it use rollups?: no
- Is it multi-chain?: will be deployed to many EVM chains
- Does it use a side-chain?: no

Tests

See Install & Usage below for information on how to run tests.

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Seaport

Seaport is a new marketplace protocol for safely and efficiently buying and selling NFTs.

Table of Contents

• Seaport
  • Table of Contents
  • Background
  • Deployments
  • Diagram
  • Install
  • Usage
    • Foundry Tests
  • Audits
  • Contributing
  • License

Background

Seaport is a marketplace protocol for safely and efficiently buying and selling NFTs. Each listing contains an arbitrary number of items that the offerer is willing to give (the "offer") along with an arbitrary number of items that must be received along with their respective receivers (the "consideration").

See the documentation, the interface, and the full interface documentation for more information on Seaport.

Deployments

On Ethereum, Rinkeby, Goerli, Kovan, Sepolia, Polygon, Mumbai, Optimism, OptimisticKovan, Arbitrum, ArbitrumNova, ArbitrumRinkeby, AvalancheFuji, AvalancheC-Chain, GnosisChain, BSC:

• Seaport 1.1: 0x00000000006c3852cbEf3e08E8dF289169EdE581
• ConduitController: 0x00000000F9490004C11Cef243f5400493c00Ad63

To be deployed on other EVM chains, such as:

• Klaytn
• Baobab
• Skale
• Celo
• Fantom
• RSK

To deploy to a new EVM chain, follow the steps outlined here.

Diagram

For a more thorough flowchart see Seaport diagram.

Install

To install dependencies and compile contracts:

yarn install
yarn build

Usage

To run hardhat tests written in javascript:

yarn test
yarn coverage

Note: artifacts and cache folders may occasionally need to be removed between standard and coverage test runs.

To run hardhat tests against reference contracts:

yarn test:ref
yarn coverage:ref

To profile gas usage:

yarn profile

Foundry Tests

Seaport also includes a suite of fuzzing tests written in solidity with Foundry.

To install Foundry (assuming a Linux or macOS system):

curl -L https://foundry.paradigm.xyz | bash

This will download foundryup. To start Foundry, run:

foundryup

To install dependencies:

forge install

To precompile contracts:

The optimized contracts are compiled using the IR pipeline, which can take a long time to compile. By default, the differential test suite deploys precompiled versions of both the optimized and reference contracts. Precompilation can be done by specifying specific Foundry profiles.

FOUNDRY_PROFILE=optimized forge build
FOUNDRY_PROFILE=reference forge build

There are three Foundry profiles for running the test suites, which bypass the IR pipeline to speed up compilation. To run tests, run any of the following:

FOUNDRY_PROFILE=test forge test # with 5000 fuzz runs
FOUNDRY_PROFILE=lite forge test # with 1000 fuzz runs
FOUNDRY_PROFILE=local forge test # compiles and deploys ReferenceConsideration normally, with 1000 fuzz runs
FOUNDRY_PROFILE=debug forge test # compiles and deploys Consideration and ReferenceConsideration using default profile solc settings, not from precompiled source, with 1000 fuzz runs

You may wish to include a .env file that exports a specific profile when developing locally.

Note that stack+debug traces will not be available for precompiled contracts. To facilitate local development, specifying FOUNDRY_PROFILE=local will compile and deploy the reference implementation normally, allowing for stack+debug traces.

Note the local profile uses Forge's ffi flag. ffi can potentially be unsafe, as it allows Forge to execute arbitrary code. Use with caution, and always ensure you trust the code in this repository, especially when working on third-party forks.

The following modifiers are also available:

• Level 2 (-vv): Logs emitted during tests are also displayed.
• Level 3 (-vvv): Stack traces for failing tests are also displayed.
• Level 4 (-vvvv): Stack traces for all tests are displayed, and setup traces for failing tests are displayed.
• Level 5 (-vvvvv): Stack traces and setup traces are always displayed.

FOUNDRY_PROFILE=test forge test  -vv

For more information on foundry testing and use, see Foundry Book installation instructions.

To run lint checks:

yarn lint:check

Lint checks utilize prettier, prettier-plugin-solidity, and solhint.

"prettier": "^2.5.1",
"prettier-plugin-solidity": "^1.0.0-beta.19",

Audits

OpenSea engaged Trail of Bits to audit the security of Seaport. From April 18th to May 12th 2022, a team of Trail of Bits consultants conducted a security review of Seaport. The audit did not uncover significant flaws that could result in the compromise of a smart contract, loss of funds, or unexpected behavior in the target system. Their full report is available here.

Contributing

Contributions to Seaport are welcome by anyone interested in writing more tests, improving readability, optimizing for gas efficiency, or extending the protocol via new zone contracts or other features.

When making a pull request, ensure that:

• All tests pass.
• Code coverage remains at 100% (coverage tests must currently be written in hardhat).
• All new code adheres to the style guide:
  • All lint checks pass.
  • Code is thoroughly commented with natspec where relevant.
• If making a change to the contracts:
  • Gas snapshots are provided and demonstrate an improvement (or an acceptable deficit given other improvements).
  • Reference contracts are modified correspondingly if relevant.
  • New tests (ideally via foundry) are included for all new features or code paths.
• If making a modification to third-party dependencies, yarn audit passes.
• A descriptive summary of the PR has been provided.

License

MIT Copyright 2023 Ozone Networks, Inc.