Policies

A Policy is a lightweight contract that can inspect a node call and revert if a rule is violated (e.g., pause, cap, whitelist). Policies are attached to specific function selectors on a node. Whenever that selector executes, the node calls policy.onCheck(caller, msg.data). Any revert in the policy reverts the underlying node call.

Which Policy contracts may be attached is controlled by the NodeRegistry via a Merkle root. Node owners can only attach policies included in that root for the given selector.

Managing Policies on a Node

1. Authorization: The protocol owner sets NodeRegistry.policiesRoot, a Merkle root over (function selector, policy address) pairs. A node owner must supply a valid Merkle multi-proof when attaching policies.

2. Attach: Node.addPolicies(proof, proofFlags, sigs, policies) (owner only) validates the proof against the registry root and appends each policy under its selector. PolicyAdded events are emitted and sigPolicy is flagged.

3. Detach: Node.removePolicies(sigs, policies) (owner only) removes the mapping and emits PolicyRemoved.

4. Inspect: Node.getPolicies(selector) returns the ordered list of policies for a selector; Node.isSigPolicy(selector, policy) returns a boolean.

5. Provide user data: If a policy expects auxiliary data (e.g., Merkle proofs for whitelist), users call Node.submitPolicyData(selector, policy, abi.encode(payload)) once. The policy caches the payload for that user/node pair and uses it on subsequent checks.

Commonly Guarded Node Functions

The current set of policies can fire on:

• deposit, mint, requestRedeem, redeem, withdraw

• transfer, approve, transferFrom

• startRebalance, execute, payManagementFees, subtractProtocolExecutionFee, updateTotalAssets

• fulfillRedeemFromReserve, finalizeRedemption, setOperator