From 37270eb08a15f096e9af38610dabdeacff0b0351 Mon Sep 17 00:00:00 2001 From: Francisco Date: Fri, 30 Jun 2023 16:52:45 -0300 Subject: [PATCH] Add security considerations to ERC2771Forwarder (#4406) --- contracts/metatx/ERC2771Forwarder.sol | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/contracts/metatx/ERC2771Forwarder.sol b/contracts/metatx/ERC2771Forwarder.sol index 290b438b8aa..f271d5d3b4d 100644 --- a/contracts/metatx/ERC2771Forwarder.sol +++ b/contracts/metatx/ERC2771Forwarder.sol @@ -20,6 +20,25 @@ import {Address} from "../utils/Address.sol"; * * `nonce`: A unique transaction ordering identifier to avoid replayability and request invalidation. * * `deadline`: A timestamp after which the request is not executable anymore. * * `data`: Encoded `msg.data` to send with the requested call. + * + * Relayers are able to submit batches if they are processing a high volume of requests. With high + * throughput, relayers may run into limitations of the chain such as limits on the number of + * transactions in the mempool. In these cases the recommendation is to distribute the load among + * multiple accounts. + * + * ==== Security Considerations + * + * If a relayer submits a forward request, it should be willing to pay up to 100% of the gas amount + * specified in the request. This contract does not implement any kind of retribution for this gas, + * and it is assumed that there is an out of band incentive for relayers to pay for execution on + * behalf of signers. Often, the relayer is operated by a project that will consider it a user + * acquisition cost. + * + * By offering to pay for gas, relayers are at risk of having that gas used by an attacker toward + * some other purpose that is not aligned with the expected out of band incentives. If you operate a + * relayer, consider whitelisting target contracts and function selectors. When relaying ERC-721 or + * ERC-1155 transfers specifically, consider rejecting the use of the `data` field, since it can be + * used to execute arbitrary code. */ contract ERC2771Forwarder is EIP712, Nonces { using ECDSA for bytes32;