diff --git a/certora/harnesses/NoncesHarness.sol b/certora/harnesses/NoncesHarness.sol new file mode 100644 index 000000000..beea5fdab --- /dev/null +++ b/certora/harnesses/NoncesHarness.sol @@ -0,0 +1,14 @@ +// SPDX-License-Identifier: MIT +pragma solidity ^0.8.20; + +import {Nonces} from "../patched/utils/Nonces.sol"; + +contract NoncesHarness is Nonces { + function useNonce(address account) external returns (uint256) { + return _useNonce(account); + } + + function useCheckedNonce(address account, uint256 nonce) external { + _useCheckedNonce(account, nonce); + } +} diff --git a/certora/specs.json b/certora/specs.json index 20b02a03a..a89419092 100644 --- a/certora/specs.json +++ b/certora/specs.json @@ -101,5 +101,10 @@ "contract": "TimelockControllerHarness", "files": ["certora/harnesses/TimelockControllerHarness.sol"], "options": ["--optimistic_hashing", "--optimistic_loop"] + }, + { + "spec": "Nonces", + "contract": "NoncesHarness", + "files": ["certora/harnesses/NoncesHarness.sol"] } ] diff --git a/certora/specs/Nonces.spec b/certora/specs/Nonces.spec new file mode 100644 index 000000000..4647c5c89 --- /dev/null +++ b/certora/specs/Nonces.spec @@ -0,0 +1,92 @@ +import "helpers/helpers.spec"; + +methods { + function nonces(address) external returns (uint256) envfree; + function useNonce(address) external returns (uint256) envfree; + function useCheckedNonce(address,uint256) external envfree; +} + +/* +┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ +│ Helpers │ +└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ +*/ +function nonceSanity(address account) returns bool { + return nonces(account) < max_uint256; +} + +/* +┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ +│ Function correctness: useNonce uses nonce │ +└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ +*/ +rule useNonce(address account) { + require nonceSanity(account); + + address other; + + mathint nonceBefore = nonces(account); + mathint otherNonceBefore = nonces(other); + + mathint nonceUsed = useNonce@withrevert(account); + bool success = !lastReverted; + + mathint nonceAfter = nonces(account); + mathint otherNonceAfter = nonces(other); + + // liveness + assert success, "doesn't revert"; + + // effect + assert nonceAfter == nonceBefore + 1 && nonceBefore == nonceUsed, "nonce is used"; + + // no side effect + assert otherNonceBefore != otherNonceAfter => other == account, "no other nonce is used"; +} + +/* +┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ +│ Function correctness: useCheckedNonce uses only the current nonce │ +└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ +*/ +rule useCheckedNonce(address account, uint256 currentNonce) { + require nonceSanity(account); + + address other; + + mathint nonceBefore = nonces(account); + mathint otherNonceBefore = nonces(other); + + useCheckedNonce@withrevert(account, currentNonce); + bool success = !lastReverted; + + mathint nonceAfter = nonces(account); + mathint otherNonceAfter = nonces(other); + + // liveness + assert success <=> to_mathint(currentNonce) == nonceBefore, "works iff current nonce is correct"; + + // effect + assert success => nonceAfter == nonceBefore + 1, "nonce is used"; + + // no side effect + assert otherNonceBefore != otherNonceAfter => other == account, "no other nonce is used"; +} + +/* +┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐ +│ Rule: nonce only increments │ +└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘ +*/ +rule nonceOnlyIncrements(address account) { + require nonceSanity(account); + + mathint nonceBefore = nonces(account); + + env e; method f; calldataarg args; + f(e, args); + + mathint nonceAfter = nonces(account); + + assert nonceAfter == nonceBefore || nonceAfter == nonceBefore + 1, "nonce only increments"; +}