Basin audit details

Total Prize Pool: $37,750 in USDC
- HM awards: $23,520 in USDC
- QA awards: $980 in USDC
- Judge awards: $4,500 in USDC
- Validator awards: $2,000 in USDC
- Scout awards: $750 in USDC
- Mitigation Review: $6,000 in USDC (Opportunity goes to top 3 backstage wardens based on placement in this audit who RSVP.)
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Starts July 29, 2024 20:00 UTC
Ends August 8, 2024 20:00 UTC

Automated Findings / Publicly Known Issues

The 4naly3er report can be found here.

Note for C4 wardens: Anything included in this Automated Findings / Publicly Known Issues section is considered a publicly known issue and is ineligible for awards.

All findings in the following audit reports:

06/16/23: Basin Halborn Report @ e5441fc
06/16/23: Basin Cyfrin Report @ e5441fc
10/05/23: Basin Code4rena Report @ 7e51c02
All bug reports from the Immunefi program listed here.

Overview

Basin

Code Version: 1.0.0 Whitepaper Version: 1.0.0

Multi Flow

The Multi Flow Pump implementation is also included in this repository at MultiFlowPump.sol.

Code Version: 1.0.0 Whitepaper Version: 1.0.0

About

Basin is a composable EVM-native decentralized exchange protocol.

Audits
Documentation
- Motivation
License

Audits

Documentation

A {Well} is a constant function AMM that allows the provisioning of liquidity into a single pooled on-chain liquidity position.

Each Well is defined by its Tokens, Well function, and Pump.

The Tokens define the set of ERC-20 tokens that can be exchanged in the Well.
The Well function defines an invariant relationship between the Well's reserves and the supply of LP tokens. See {IWellFunction}.
Pumps are an on-chain oracles that are updated upon each interaction with the Well. See {IPump}.

A Well's tokens, Well function, and Pump are stored as immutable variables during Well construction to prevent unnecessary SLOAD calls during operation.

Wells support swapping, adding liquidity, and removing liquidity in balanced or imbalanced proportions.

Wells maintain two components of state:

a balance of tokens received through Well operations ("reserves")
an ERC-20 LP token representing pro-rata ownership of the reserves

Well functions and Pumps can independently choose to be stateful or stateless.

Including a Pump is optional.

Each Well implements ERC-20, ERC-2612 and the {IWell} interface.

Motivation

Allowing composability of the pricing function and oracle at the Well level is a deliberate design decision with significant implications.

In particular, a standard AMM interface invoking composable components allows for developers to iterate upon the underlying pricing functions and oracles, which greatly impacts gas and capital efficiency.

However, this architecture shifts much of the attack surface area to the Well's components. Users of Wells should be aware that anyone can deploy a Well with malicious components, and that new Wells SHOULD NOT be trusted without careful review. This understanding is particularly important in the DeFi context in which Well data may be consumed via on-chain registries or off-chain indexing systems.

The Wells architecture aims to outline a simple interface for composable AMMs and leave the process of evaluating a given Well's trustworthiness as the responsibility of the user. To this end, future work may focus on development of on-chain Well registries and factories which create or highlight Wells composed of known components.

An example factory implementation is provided in {Aquifer} without any opinion regarding the trustworthiness of Well functions and the Pumps using it. Wells are not required to be deployed via this mechanism.

License

MIT

Scope

See scope.txt

Files in scope

File	Logic Contracts	Interfaces	nSLOC	Libraries used
/src/functions/Stable2.sol	1	****	194	src/interfaces/IBeanstalkWellFunction.sol, src/interfaces/ILookupTable.sol, src/functions/ProportionalLPToken2.sol, forge-std/interfaces/IERC20.sol
/src/functions/StableLUT/Stable2LUT1.sol	1	****	2150	src/interfaces/ILookupTable.sol
/src/WellUpgradeable.sol	1	****	70	src/Well.sol, ozu/proxy/utils/UUPSUpgradeable.sol, ozu/access/OwnableUpgradeable.sol, oz/token/ERC20/utils/SafeERC20.sol, src/interfaces/IAquifer.sol
Totals	3	****	2414

Files out of scope

See out_of_scope.txt

File
./mocks/functions/MockEmptyFunction.sol
./mocks/functions/MockFunctionBad.sol
./mocks/pumps/MockFailPump.sol
./mocks/pumps/MockPump.sol
./mocks/tokens/MockToken.sol
./mocks/tokens/MockTokenFeeOnTransfer.sol
./mocks/tokens/MockTokenNoName.sol
./mocks/tokens/ReentrantMockToken.sol
./mocks/wells/MockInitFailWell.sol
./mocks/wells/MockReserveWell.sol
./mocks/wells/MockStaticWell.sol
./mocks/wells/MockWellUpgradeable.sol
./script/deploy/Aquifer.s.sol
./script/deploy/AquiferWell.s.sol
./script/deploy/MockPump.s.sol
./script/deploy/Well.s.sol
./script/deploy/helpers/Logger.sol
./script/helpers/WellDeployer.sol
./script/simulations/stableswap/StableswapCalcRatiosLiqSim.s.sol
./script/simulations/stableswap/StableswapCalcRatiosSwapSim.s.sol
./src/Aquifer.sol
./src/Well.sol
./src/functions/ConstantProduct.sol
./src/functions/ConstantProduct2.sol
./src/functions/ProportionalLPToken.sol
./src/functions/ProportionalLPToken2.sol
./src/interfaces/IAquifer.sol
./src/interfaces/IBeanstalkWellFunction.sol
./src/interfaces/ILookupTable.sol
./src/interfaces/IMultiFlowPumpWellFunction.sol
./src/interfaces/IWell.sol
./src/interfaces/IWellErrors.sol
./src/interfaces/IWellFunction.sol
./src/interfaces/pumps/ICumulativePump.sol
./src/interfaces/pumps/IInstantaneousPump.sol
./src/interfaces/pumps/IMultiFlowPumpErrors.sol
./src/interfaces/pumps/IPump.sol
./src/libraries/ABDKMathQuad.sol
./src/libraries/LibBytes.sol
./src/libraries/LibBytes16.sol
./src/libraries/LibClone.sol
./src/libraries/LibContractInfo.sol
./src/libraries/LibLastReserveBytes.sol
./src/libraries/LibMath.sol
./src/libraries/LibWellConstructor.sol
./src/libraries/LibWellUpgradeableConstructor.sol
./src/pumps/MultiFlowPump.sol
./src/utils/Clone.sol
./src/utils/ClonePlus.sol
./test/Aquifer.t.sol
./test/LiquidityHelper.sol
./test/Stable2/LookupTable.t.sol
./test/Stable2/Well.Stable2.AddLiquidity.t.sol
./test/Stable2/Well.Stable2.Bore.t.sol
./test/Stable2/Well.Stable2.RemoveLiquidity.t.sol
./test/Stable2/Well.Stable2.RemoveLiquidityImbalanced.t.sol
./test/Stable2/Well.Stable2.RemoveLiquidityOneToken.t.sol
./test/Stable2/Well.Stable2.Shift.t.sol
./test/Stable2/Well.Stable2.Skim.t.sol
./test/Stable2/Well.Stable2.SwapFrom.t.sol
./test/Stable2/Well.Stable2.SwapTo.t.sol
./test/SwapHelper.sol
./test/TestHelper.sol
./test/Well.AddLiquidity.t.sol
./test/Well.AddLiquidityFeeOnTransfer.Fee.t.sol
./test/Well.AddLiquidityFeeOnTransfer.NoFee.t.sol
./test/Well.Bore.t.sol
./test/Well.DuplicateTokens.t.sol
./test/Well.FeeOnTransfer.t.sol
./test/Well.ReadOnlyReentrancy.t.sol
./test/Well.RemoveLiquidity.t.sol
./test/Well.RemoveLiquidityImbalanced.t.sol
./test/Well.RemoveLiquidityOneToken.t.sol
./test/Well.Shift.t.sol
./test/Well.Skim.t.sol
./test/Well.SucceedOnPumpFailure.t.sol
./test/Well.SwapFrom.t.sol
./test/Well.SwapFromFeeOnTransfer.Fee.t.sol
./test/Well.SwapFromFeeOnTransfer.NoFee.t.sol
./test/Well.SwapTo.t.sol
./test/Well.Sync.t.sol
./test/Well.Tokens.t.sol
./test/Well.UpdatePump.t.sol
./test/WellUpgradeable.t.sol
./test/beanstalk/BeanstalkConstantProduct.calcReserveAtRatioLiquidity.t.sol
./test/beanstalk/BeanstalkConstantProduct.calcReserveAtRatioSwap.t.sol
./test/beanstalk/BeanstalkConstantProduct2.calcReserveAtRatioLiquidity.t.sol
./test/beanstalk/BeanstalkConstantProduct2.calcReserveAtRatioSwap.t.sol
./test/beanstalk/BeanstalkStable2.calcReserveAtRatioLiquidity.t.sol
./test/beanstalk/BeanstalkStable2.calcReserveAtRatioSwap.t.sol
./test/functions/ConstantProduct.t.sol
./test/functions/ConstantProduct2.t.sol
./test/functions/Stable2.t.sol
./test/functions/WellFunctionHelper.sol
./test/helpers/Users.sol
./test/integration/GasMetering.sol
./test/integration/IntegrationTestGasComparisons.sol
./test/integration/IntegrationTestHelper.sol
./test/integration/interfaces/ICurve.sol
./test/integration/interfaces/IPipeline.sol
./test/integration/interfaces/IUniswap.sol
./test/invariant/Handler.t.sol
./test/invariant/Invariants.t.sol
./test/libraries/LibBytes.t.sol
./test/libraries/LibBytes16.t.sol
./test/libraries/LibContractInfo.t.sol
./test/libraries/LibLastReserveBytes.t.sol
./test/libraries/LibMath.t.sol
./test/libraries/TestABDK.t.sol
./test/pumps/Pump.CapReserves.t.sol
./test/pumps/Pump.Fuzz.t.sol
./test/pumps/Pump.Helpers.t.sol
./test/pumps/Pump.Longevity.t.sol
./test/pumps/Pump.NotInitialized.t.sol
./test/pumps/Pump.TimeWeightedAverage.t.sol
./test/pumps/Pump.Update.t.sol
./test/pumps/PumpHelpers.sol
Totals: 117

Scoping Q & A

General questions

Question	Answer
ERC20 used by the protocol	Any (all possible ERC20s)
Test coverage	Lines: 81.80% - Functions: 81.19%
ERC721 used by the protocol	None
ERC777 used by the protocol	None
ERC1155 used by the protocol	None
Chains the protocol will be deployed on	Ethereum

ERC20 token behaviors in scope

Question	Answer
Missing return values	Out of scope
Fee on transfer	Out of scope
Balance changes outside of transfers	Out of scope
Upgradeability	In scope
Flash minting	Out of scope
Pausability	Out of scope
Approval race protections	Out of scope
Revert on approval to zero address	Out of scope
Revert on zero value approvals	Out of scope
Revert on zero value transfers	Out of scope
Revert on transfer to the zero address	Out of scope
Revert on large approvals and/or transfers	Out of scope
Doesn't revert on failure	Out of scope
Multiple token addresses	Out of scope
Low decimals ( < 6)	Out of scope
High decimals ( > 18)	Out of scope
Blocklists	Out of scope

External integrations (e.g., Uniswap) behavior in scope:

Question	Answer
Enabling/disabling fees (e.g. Blur disables/enables fees)	No
Pausability (e.g. Uniswap pool gets paused)	No
Upgradeability (e.g. Uniswap gets upgraded)	No

EIP compliance

src/WellUpgradeable.sol: should comply with EIP-1822

Additional context

Main invariants

None

Attack ideas (where to focus for bugs)

None

All trusted roles in the protocol

N/A

Describe any novel or unique curve logic or mathematical models implemented in the contracts:

With regard to the Stable 2 Well Function, a lookup table is used to assist the Newtonian estimation to decrease the computation needed to converge to an answer. See in line comments.

Running tests

Setup the repo and requirements:

git clone https://github.com/code-423n4/2024-07-basin.git
cd 2024-07-basin
git submodule update --init --recursive
foundryup
forge install

Setup Python environment and perform the tests (Make sure your MAINNET_RPC_URL is set in .env file):

python3 -m venv env 
source env/bin/activate 
python3 -m pip install -r requirements.txt
forge test --ffi

To run code coverage:

forge coverage --ffi

File	% Lines	% Statements	% Branches	% Funcs
mocks/functions/MockEmptyFunction.sol	66.67% (2/3)	66.67% (2/3)	100.00% (0/0)	80.00% (4/5)
mocks/functions/MockFunctionBad.sol	33.33% (1/3)	25.00% (1/4)	100.00% (0/0)	60.00% (3/5)
mocks/pumps/MockFailPump.sol	100.00% (1/1)	100.00% (1/1)	100.00% (0/0)	100.00% (1/1)
mocks/pumps/MockPump.sol	50.00% (1/2)	50.00% (1/2)	100.00% (0/0)	50.00% (1/2)
mocks/tokens/MockToken.sol	83.33% (5/6)	83.33% (5/6)	100.00% (0/0)	80.00% (4/5)
mocks/tokens/MockTokenFeeOnTransfer.sol	81.25% (13/16)	86.36% (19/22)	100.00% (0/0)	66.67% (6/9)
mocks/tokens/ReentrantMockToken.sol	100.00% (7/7)	88.89% (8/9)	100.00% (6/6)	100.00% (3/3)
mocks/wells/MockInitFailWell.sol	100.00% (2/2)	100.00% (2/2)	100.00% (0/0)	100.00% (2/2)
mocks/wells/MockReserveWell.sol	100.00% (7/7)	100.00% (7/7)	100.00% (0/0)	100.00% (6/6)
mocks/wells/MockStaticWell.sol	100.00% (31/31)	100.00% (40/40)	100.00% (4/4)	100.00% (10/10)
mocks/wells/MockWellUpgradeable.sol	100.00% (1/1)	100.00% (1/1)	100.00% (0/0)	100.00% (1/1)
script/deploy/Aquifer.s.sol	0.00% (0/3)	0.00% (0/4)	100.00% (0/0)	0.00% (0/1)
script/deploy/AquiferWell.s.sol	0.00% (0/17)	0.00% (0/23)	100.00% (0/0)	0.00% (0/1)
script/deploy/MockPump.s.sol	0.00% (0/5)	0.00% (0/7)	100.00% (0/0)	0.00% (0/1)
script/deploy/Well.s.sol	0.00% (0/17)	0.00% (0/23)	100.00% (0/0)	0.00% (0/1)
script/deploy/helpers/Logger.sol	0.00% (0/8)	0.00% (0/8)	100.00% (0/0)	0.00% (0/1)
script/helpers/WellDeployer.sol	100.00% (6/6)	100.00% (6/6)	100.00% (0/0)	100.00% (2/2)
script/simulations/stableswap/StableswapCalcRatiosLiqSim.s.sol	0.00% (0/43)	0.00% (0/55)	100.00% (0/0)	0.00% (0/1)
script/simulations/stableswap/StableswapCalcRatiosSwapSim.s.sol	0.00% (0/57)	0.00% (0/75)	100.00% (0/0)	0.00% (0/1)
src/Aquifer.sol	100.00% (27/27)	100.00% (30/30)	100.00% (20/20)	66.67% (2/3)
src/Well.sol	98.84% (255/258)	98.65% (365/370)	100.00% (52/52)	95.92% (47/49)
src/WellUpgradeable.sol	83.33% (25/30)	86.05% (37/43)	85.71% (12/14)	80.00% (8/10)
src/functions/ConstantProduct.sol	77.27% (17/22)	70.59% (24/34)	66.67% (4/6)	75.00% (6/8)
src/functions/ConstantProduct2.sol	100.00% (12/12)	100.00% (16/16)	100.00% (2/2)	100.00% (7/7)
src/functions/ProportionalLPToken.sol	0.00% (0/3)	0.00% (0/5)	100.00% (0/0)	0.00% (0/1)
src/functions/ProportionalLPToken2.sol	100.00% (3/3)	100.00% (3/3)	100.00% (0/0)	100.00% (1/1)
src/functions/Stable2.sol	92.11% (105/114)	92.70% (165/178)	84.78% (39/46)	85.71% (12/14)
src/functions/StableLUT/Stable2LUT1.sol	94.84% (386/407)	94.84% (386/407)	94.80% (383/404)	100.00% (3/3)
src/libraries/ABDKMathQuad.sol	73.26% (778/1062)	73.37% (1149/1566)	77.16% (696/902)	46.88% (15/32)
src/libraries/LibBytes.sol	100.00% (26/26)	100.00% (33/33)	100.00% (18/18)	100.00% (2/2)
src/libraries/LibBytes16.sol	100.00% (21/21)	100.00% (28/28)	100.00% (8/8)	100.00% (2/2)
src/libraries/LibClone.sol	88.66% (86/97)	88.89% (88/99)	80.00% (4/5)	90.00% (9/10)
src/libraries/LibContractInfo.sol	66.67% (8/12)	61.54% (8/13)	50.00% (2/4)	66.67% (2/3)
src/libraries/LibLastReserveBytes.sol	97.56% (40/41)	98.18% (54/55)	100.00% (14/14)	75.00% (3/4)
src/libraries/LibMath.sol	98.53% (67/68)	96.59% (85/88)	100.00% (24/24)	100.00% (4/4)
src/libraries/LibWellConstructor.sol	92.86% (13/14)	94.74% (18/19)	100.00% (0/0)	75.00% (3/4)
src/libraries/LibWellUpgradeableConstructor.sol	92.86% (13/14)	94.74% (18/19)	100.00% (0/0)	75.00% (3/4)
src/pumps/MultiFlowPump.sol	96.45% (190/197)	96.39% (267/277)	96.15% (50/52)	100.00% (21/21)
src/utils/Clone.sol	41.67% (5/12)	38.89% (7/18)	100.00% (0/0)	50.00% (3/6)
src/utils/ClonePlus.sol	100.00% (7/7)	100.00% (12/12)	100.00% (2/2)	100.00% (2/2)
test/LiquidityHelper.sol	63.16% (24/38)	67.80% (40/59)	100.00% (0/0)	57.14% (4/7)
test/SwapHelper.sol	92.31% (24/26)	94.29% (33/35)	100.00% (2/2)	66.67% (2/3)
test/TestHelper.sol	89.29% (150/168)	90.31% (205/227)	88.89% (16/18)	86.96% (40/46)
test/helpers/Users.sol	81.82% (9/11)	81.25% (13/16)	100.00% (0/0)	66.67% (2/3)
test/integration/IntegrationTestHelper.sol	93.55% (29/31)	92.68% (38/41)	100.00% (2/2)	100.00% (6/6)
test/invariant/Handler.t.sol	89.96% (233/259)	90.29% (316/350)	100.00% (36/36)	90.91% (20/22)
Total	81.80% (2630/3215)	81.38% (3531/4339)	85.07% (1396/1641)	81.19% (272/335)

To run gas benchmarks:

forge test --ffi --gas-report

Miscellaneous

Employees of Beanstalk Farms contributors and employees' family members are ineligible to participate in this audit.

code-423n4/2024-07-basin