// Copyright (C) Parity Technologies (UK) Ltd. // This file is part of Parity Bridges Common. // Parity Bridges Common is free software: you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // Parity Bridges Common is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with Parity Bridges Common. If not, see . use crate::{ weights::WeightInfo, BestFinalized, BridgedBlockNumber, BridgedHeader, Config, CurrentAuthoritySet, Error, FreeHeadersRemaining, Pallet, }; use bp_header_chain::{ justification::GrandpaJustification, max_expected_submit_finality_proof_arguments_size, ChainWithGrandpa, GrandpaConsensusLogReader, }; use bp_runtime::{BlockNumberOf, Chain, OwnedBridgeModule}; use codec::Encode; use frame_support::{ dispatch::CallableCallFor, traits::{Get, IsSubType}, weights::Weight, }; use sp_consensus_grandpa::SetId; use sp_runtime::{ traits::{CheckedSub, Header, Zero}, transaction_validity::{InvalidTransaction, TransactionValidityError}, RuntimeDebug, SaturatedConversion, }; /// Info about a `SubmitParachainHeads` call which tries to update a single parachain. #[derive(Copy, Clone, PartialEq, RuntimeDebug)] pub struct SubmitFinalityProofInfo { /// Number of the finality target. pub block_number: N, /// An identifier of the validators set that has signed the submitted justification. /// It might be `None` if deprecated version of the `submit_finality_proof` is used. pub current_set_id: Option, /// If `true`, then the call proves new **mandatory** header. pub is_mandatory: bool, /// If `true`, then the call must be free (assuming that everything else is valid) to /// be treated as valid. pub is_free_execution_expected: bool, /// Extra weight that we assume is included in the call. /// /// We have some assumptions about headers and justifications of the bridged chain. /// We know that if our assumptions are correct, then the call must not have the /// weight above some limit. The fee paid for weight above that limit, is never refunded. pub extra_weight: Weight, /// Extra size (in bytes) that we assume are included in the call. /// /// We have some assumptions about headers and justifications of the bridged chain. /// We know that if our assumptions are correct, then the call must not have the /// weight above some limit. The fee paid for bytes above that limit, is never refunded. pub extra_size: u32, } /// Verified `SubmitFinalityProofInfo`. #[derive(Copy, Clone, PartialEq, RuntimeDebug)] pub struct VerifiedSubmitFinalityProofInfo { /// Base call information. pub base: SubmitFinalityProofInfo, /// A difference between bundled bridged header and best bridged header known to us /// before the call. pub improved_by: N, } impl SubmitFinalityProofInfo { /// Returns `true` if call size/weight is below our estimations for regular calls. pub fn fits_limits(&self) -> bool { self.extra_weight.is_zero() && self.extra_size.is_zero() } } /// Helper struct that provides methods for working with the `SubmitFinalityProof` call. pub struct SubmitFinalityProofHelper, I: 'static> { _phantom_data: sp_std::marker::PhantomData<(T, I)>, } impl, I: 'static> SubmitFinalityProofHelper { /// Returns `true` if we may fit more free headers into the current block. If `false` is /// returned, the call will be paid even if `is_free_execution_expected` has been set /// to `true`. pub fn can_import_anything_for_free() -> bool { // `unwrap_or(u32::MAX)` means that if `FreeHeadersRemaining` is `None`, we may accept // this header for free. That is a small cheat - is is `None` if executed outside of // transaction (e.g. during block initialization). Normal relayer would never submit // such calls, but if he did, that is not our problem. During normal transactions, // the `FreeHeadersRemaining` is always `Some(_)`. let free_headers_remaining = FreeHeadersRemaining::::get().unwrap_or(u32::MAX); if free_headers_remaining == 0 { return false } true } /// Check that the: (1) GRANDPA head provided by the `SubmitFinalityProof` is better than the /// best one we know (2) if `current_set_id` matches the current authority set id, if specified /// and (3) whether transaction MAY be free for the submitter if `is_free_execution_expected` /// is `true`. /// /// Returns number of headers between the current best finalized header, known to the pallet /// and the bundled header. pub fn check_obsolete_from_extension( call_info: &SubmitFinalityProofInfo>, ) -> Result, Error> { // do basic checks first let improved_by = Self::check_obsolete(call_info.block_number, call_info.current_set_id)?; // if submitter has NOT specified that it wants free execution, then we are done if !call_info.is_free_execution_expected { return Ok(improved_by); } // else - if we can not accept more free headers, "reject" the transaction if !Self::can_import_anything_for_free() { log::trace!( target: crate::LOG_TARGET, "Cannot accept free {:?} header {:?}. No more free slots remaining", T::BridgedChain::ID, call_info.block_number, ); return Err(Error::::FreeHeadersLimitExceded); } // ensure that the `improved_by` is larger than the configured free interval if !call_info.is_mandatory { if let Some(free_headers_interval) = T::FreeHeadersInterval::get() { if improved_by < free_headers_interval.into() { log::trace!( target: crate::LOG_TARGET, "Cannot accept free {:?} header {:?}. Too small difference \ between submitted headers: {:?} vs {}", T::BridgedChain::ID, call_info.block_number, improved_by, free_headers_interval, ); return Err(Error::::BelowFreeHeaderInterval); } } } // we do not check whether the header matches free submission criteria here - it is the // relayer responsibility to check that Ok(improved_by) } /// Check that the GRANDPA head provided by the `SubmitFinalityProof` is better than the best /// one we know. Additionally, checks if `current_set_id` matches the current authority set /// id, if specified. This method is called by the call code and the transaction extension, /// so it does not check the free execution. /// /// Returns number of headers between the current best finalized header, known to the pallet /// and the bundled header. pub fn check_obsolete( finality_target: BlockNumberOf, current_set_id: Option, ) -> Result, Error> { let best_finalized = BestFinalized::::get().ok_or_else(|| { log::trace!( target: crate::LOG_TARGET, "Cannot finalize header {:?} because pallet is not yet initialized", finality_target, ); >::NotInitialized })?; let improved_by = match finality_target.checked_sub(&best_finalized.number()) { Some(improved_by) if improved_by > Zero::zero() => improved_by, _ => { log::trace!( target: crate::LOG_TARGET, "Cannot finalize obsolete header: bundled {:?}, best {:?}", finality_target, best_finalized, ); return Err(Error::::OldHeader) }, }; if let Some(current_set_id) = current_set_id { let actual_set_id = >::get().set_id; if current_set_id != actual_set_id { log::trace!( target: crate::LOG_TARGET, "Cannot finalize header signed by unknown authority set: bundled {:?}, best {:?}", current_set_id, actual_set_id, ); return Err(Error::::InvalidAuthoritySetId) } } Ok(improved_by) } /// Check if the `SubmitFinalityProof` was successfully executed. pub fn was_successful(finality_target: BlockNumberOf) -> bool { match BestFinalized::::get() { Some(best_finalized) => best_finalized.number() == finality_target, None => false, } } } /// Trait representing a call that is a sub type of this pallet's call. pub trait CallSubType, I: 'static>: IsSubType, T>> { /// Extract finality proof info from a runtime call. fn submit_finality_proof_info( &self, ) -> Option>> { if let Some(crate::Call::::submit_finality_proof { finality_target, justification }) = self.is_sub_type() { return Some(submit_finality_proof_info_from_args::( finality_target, justification, None, false, )) } else if let Some(crate::Call::::submit_finality_proof_ex { finality_target, justification, current_set_id, is_free_execution_expected, }) = self.is_sub_type() { return Some(submit_finality_proof_info_from_args::( finality_target, justification, Some(*current_set_id), *is_free_execution_expected, )) } None } /// Validate Grandpa headers in order to avoid "mining" transactions that provide outdated /// bridged chain headers. Without this validation, even honest relayers may lose their funds /// if there are multiple relays running and submitting the same information. /// /// Returns `Ok(None)` if the call is not the `submit_finality_proof` call of our pallet. /// Returns `Ok(Some(_))` if the call is the `submit_finality_proof` call of our pallet and /// we believe the call brings header that improves the pallet state. /// Returns `Err(_)` if the call is the `submit_finality_proof` call of our pallet and we /// believe that the call will fail. fn check_obsolete_submit_finality_proof( &self, ) -> Result< Option>>, TransactionValidityError, > where Self: Sized, { let call_info = match self.submit_finality_proof_info() { Some(finality_proof) => finality_proof, _ => return Ok(None), }; if Pallet::::ensure_not_halted().is_err() { return Err(InvalidTransaction::Call.into()) } let result = SubmitFinalityProofHelper::::check_obsolete_from_extension(&call_info); match result { Ok(improved_by) => Ok(Some(VerifiedSubmitFinalityProofInfo { base: call_info, improved_by })), Err(Error::::OldHeader) => Err(InvalidTransaction::Stale.into()), Err(_) => Err(InvalidTransaction::Call.into()), } } } impl, I: 'static> CallSubType for T::RuntimeCall where T::RuntimeCall: IsSubType, T>> { } /// Extract finality proof info from the submitted header and justification. pub(crate) fn submit_finality_proof_info_from_args, I: 'static>( finality_target: &BridgedHeader, justification: &GrandpaJustification>, current_set_id: Option, is_free_execution_expected: bool, ) -> SubmitFinalityProofInfo> { let block_number = *finality_target.number(); // the `submit_finality_proof` call will reject justifications with invalid, duplicate, // unknown and extra signatures. It'll also reject justifications with less than necessary // signatures. So we do not care about extra weight because of additional signatures here. let precommits_len = justification.commit.precommits.len().saturated_into(); let required_precommits = precommits_len; // We do care about extra weight because of more-than-expected headers in the votes // ancestries. But we have problems computing extra weight for additional headers (weight of // additional header is too small, so that our benchmarks aren't detecting that). So if there // are more than expected headers in votes ancestries, we will treat the whole call weight // as an extra weight. let votes_ancestries_len = justification.votes_ancestries.len().saturated_into(); let extra_weight = if votes_ancestries_len > T::BridgedChain::REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY { T::WeightInfo::submit_finality_proof(precommits_len, votes_ancestries_len) } else { Weight::zero() }; // check if the `finality_target` is a mandatory header. If so, we are ready to refund larger // size let is_mandatory_finality_target = GrandpaConsensusLogReader::>::find_scheduled_change( finality_target.digest(), ) .is_some(); // we can estimate extra call size easily, without any additional significant overhead let actual_call_size: u32 = finality_target .encoded_size() .saturating_add(justification.encoded_size()) .saturated_into(); let max_expected_call_size = max_expected_submit_finality_proof_arguments_size::( is_mandatory_finality_target, required_precommits, ); let extra_size = actual_call_size.saturating_sub(max_expected_call_size); SubmitFinalityProofInfo { block_number, current_set_id, is_mandatory: is_mandatory_finality_target, is_free_execution_expected, extra_weight, extra_size, } } #[cfg(test)] mod tests { use crate::{ call_ext::CallSubType, mock::{ run_test, test_header, FreeHeadersInterval, RuntimeCall, TestBridgedChain, TestNumber, TestRuntime, }, BestFinalized, Config, CurrentAuthoritySet, FreeHeadersRemaining, PalletOperatingMode, StoredAuthoritySet, SubmitFinalityProofInfo, WeightInfo, }; use bp_header_chain::ChainWithGrandpa; use bp_runtime::{BasicOperatingMode, HeaderId}; use bp_test_utils::{ make_default_justification, make_justification_for_header, JustificationGeneratorParams, TEST_GRANDPA_SET_ID, }; use codec::Encode; use frame_support::weights::Weight; use sp_runtime::{testing::DigestItem, traits::Header as _, SaturatedConversion}; fn validate_block_submit(num: TestNumber) -> bool { let bridge_grandpa_call = crate::Call::::submit_finality_proof_ex { finality_target: Box::new(test_header(num)), justification: make_default_justification(&test_header(num)), // not initialized => zero current_set_id: 0, is_free_execution_expected: false, }; RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call, )) .is_ok() } fn sync_to_header_10() { let header10_hash = sp_core::H256::default(); BestFinalized::::put(HeaderId(10, header10_hash)); } #[test] fn extension_rejects_obsolete_header() { run_test(|| { // when current best finalized is #10 and we're trying to import header#5 => tx is // rejected sync_to_header_10(); assert!(!validate_block_submit(5)); }); } #[test] fn extension_rejects_same_header() { run_test(|| { // when current best finalized is #10 and we're trying to import header#10 => tx is // rejected sync_to_header_10(); assert!(!validate_block_submit(10)); }); } #[test] fn extension_rejects_new_header_if_pallet_is_halted() { run_test(|| { // when pallet is halted => tx is rejected sync_to_header_10(); PalletOperatingMode::::put(BasicOperatingMode::Halted); assert!(!validate_block_submit(15)); }); } #[test] fn extension_rejects_new_header_if_set_id_is_invalid() { run_test(|| { // when set id is different from the passed one => tx is rejected sync_to_header_10(); let next_set = StoredAuthoritySet::::try_new(vec![], 0x42).unwrap(); CurrentAuthoritySet::::put(next_set); assert!(!validate_block_submit(15)); }); } #[test] fn extension_rejects_new_header_if_free_execution_is_requested_and_free_submissions_are_not_accepted( ) { run_test(|| { let bridge_grandpa_call = crate::Call::::submit_finality_proof_ex { finality_target: Box::new(test_header(10 + FreeHeadersInterval::get() as u64)), justification: make_default_justification(&test_header( 10 + FreeHeadersInterval::get() as u64, )), current_set_id: 0, is_free_execution_expected: true, }; sync_to_header_10(); // when we can accept free headers => Ok FreeHeadersRemaining::::put(2); assert!(RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call.clone(), ),) .is_ok()); // when we can NOT accept free headers => Err FreeHeadersRemaining::::put(0); assert!(RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call.clone(), ),) .is_err()); // when called outside of transaction => Ok FreeHeadersRemaining::::kill(); assert!(RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call, ),) .is_ok()); }) } #[test] fn extension_rejects_new_header_if_free_execution_is_requested_and_improved_by_is_below_expected( ) { run_test(|| { let bridge_grandpa_call = crate::Call::::submit_finality_proof_ex { finality_target: Box::new(test_header(100)), justification: make_default_justification(&test_header(100)), current_set_id: 0, is_free_execution_expected: true, }; sync_to_header_10(); // when `improved_by` is less than the free interval BestFinalized::::put(HeaderId( 100 - FreeHeadersInterval::get() as u64 + 1, sp_core::H256::default(), )); assert!(RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call.clone(), ),) .is_err()); // when `improved_by` is equal to the free interval BestFinalized::::put(HeaderId( 100 - FreeHeadersInterval::get() as u64, sp_core::H256::default(), )); assert!(RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call.clone(), ),) .is_ok()); // when `improved_by` is larger than the free interval BestFinalized::::put(HeaderId( 100 - FreeHeadersInterval::get() as u64 - 1, sp_core::H256::default(), )); assert!(RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call.clone(), ),) .is_ok()); // when `improved_by` is less than the free interval BUT it is a mandatory header let mut mandatory_header = test_header(100); let consensus_log = sp_consensus_grandpa::ConsensusLog::::ScheduledChange( sp_consensus_grandpa::ScheduledChange { next_authorities: bp_test_utils::authority_list(), delay: 0, }, ); mandatory_header.digest = sp_runtime::Digest { logs: vec![DigestItem::Consensus( sp_consensus_grandpa::GRANDPA_ENGINE_ID, consensus_log.encode(), )], }; let justification = make_justification_for_header(JustificationGeneratorParams { header: mandatory_header.clone(), set_id: 1, ..Default::default() }); let bridge_grandpa_call = crate::Call::::submit_finality_proof_ex { finality_target: Box::new(mandatory_header), justification, current_set_id: 0, is_free_execution_expected: true, }; BestFinalized::::put(HeaderId( 100 - FreeHeadersInterval::get() as u64 + 1, sp_core::H256::default(), )); assert!(RuntimeCall::check_obsolete_submit_finality_proof(&RuntimeCall::Grandpa( bridge_grandpa_call.clone(), ),) .is_ok()); }) } #[test] fn extension_accepts_new_header() { run_test(|| { // when current best finalized is #10 and we're trying to import header#15 => tx is // accepted sync_to_header_10(); assert!(validate_block_submit(15)); }); } #[test] fn submit_finality_proof_info_is_parsed() { // when `submit_finality_proof` is used, `current_set_id` is set to `None` let deprecated_call = RuntimeCall::Grandpa(crate::Call::::submit_finality_proof { finality_target: Box::new(test_header(42)), justification: make_default_justification(&test_header(42)), }); assert_eq!( deprecated_call.submit_finality_proof_info(), Some(SubmitFinalityProofInfo { block_number: 42, current_set_id: None, extra_weight: Weight::zero(), extra_size: 0, is_mandatory: false, is_free_execution_expected: false, }) ); // when `submit_finality_proof_ex` is used, `current_set_id` is set to `Some` let deprecated_call = RuntimeCall::Grandpa(crate::Call::::submit_finality_proof_ex { finality_target: Box::new(test_header(42)), justification: make_default_justification(&test_header(42)), current_set_id: 777, is_free_execution_expected: false, }); assert_eq!( deprecated_call.submit_finality_proof_info(), Some(SubmitFinalityProofInfo { block_number: 42, current_set_id: Some(777), extra_weight: Weight::zero(), extra_size: 0, is_mandatory: false, is_free_execution_expected: false, }) ); } #[test] fn extension_returns_correct_extra_size_if_call_arguments_are_too_large() { // when call arguments are below our limit => no refund let small_finality_target = test_header(1); let justification_params = JustificationGeneratorParams { header: small_finality_target.clone(), ..Default::default() }; let small_justification = make_justification_for_header(justification_params); let small_call = RuntimeCall::Grandpa(crate::Call::submit_finality_proof_ex { finality_target: Box::new(small_finality_target), justification: small_justification, current_set_id: TEST_GRANDPA_SET_ID, is_free_execution_expected: false, }); assert_eq!(small_call.submit_finality_proof_info().unwrap().extra_size, 0); // when call arguments are too large => partial refund let mut large_finality_target = test_header(1); large_finality_target .digest_mut() .push(DigestItem::Other(vec![42u8; 1024 * 1024])); let justification_params = JustificationGeneratorParams { header: large_finality_target.clone(), ..Default::default() }; let large_justification = make_justification_for_header(justification_params); let large_call = RuntimeCall::Grandpa(crate::Call::submit_finality_proof_ex { finality_target: Box::new(large_finality_target), justification: large_justification, current_set_id: TEST_GRANDPA_SET_ID, is_free_execution_expected: false, }); assert_ne!(large_call.submit_finality_proof_info().unwrap().extra_size, 0); } #[test] fn extension_returns_correct_extra_weight_if_there_are_too_many_headers_in_votes_ancestry() { let finality_target = test_header(1); let mut justification_params = JustificationGeneratorParams { header: finality_target.clone(), ancestors: TestBridgedChain::REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY, ..Default::default() }; // when there are `REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY` headers => no refund let justification = make_justification_for_header(justification_params.clone()); let call = RuntimeCall::Grandpa(crate::Call::submit_finality_proof_ex { finality_target: Box::new(finality_target.clone()), justification, current_set_id: TEST_GRANDPA_SET_ID, is_free_execution_expected: false, }); assert_eq!(call.submit_finality_proof_info().unwrap().extra_weight, Weight::zero()); // when there are `REASONABLE_HEADERS_IN_JUSTIFICATON_ANCESTRY + 1` headers => full refund justification_params.ancestors += 1; let justification = make_justification_for_header(justification_params); let call_weight = ::WeightInfo::submit_finality_proof( justification.commit.precommits.len().saturated_into(), justification.votes_ancestries.len().saturated_into(), ); let call = RuntimeCall::Grandpa(crate::Call::submit_finality_proof_ex { finality_target: Box::new(finality_target), justification, current_set_id: TEST_GRANDPA_SET_ID, is_free_execution_expected: false, }); assert_eq!(call.submit_finality_proof_info().unwrap().extra_weight, call_weight); } #[test] fn check_obsolete_submit_finality_proof_returns_correct_improved_by() { run_test(|| { fn make_call(number: u64) -> RuntimeCall { RuntimeCall::Grandpa(crate::Call::::submit_finality_proof_ex { finality_target: Box::new(test_header(number)), justification: make_default_justification(&test_header(number)), current_set_id: 0, is_free_execution_expected: false, }) } sync_to_header_10(); // when the difference between headers is 1 assert_eq!( RuntimeCall::check_obsolete_submit_finality_proof(&make_call(11)) .unwrap() .unwrap() .improved_by, 1, ); // when the difference between headers is 2 assert_eq!( RuntimeCall::check_obsolete_submit_finality_proof(&make_call(12)) .unwrap() .unwrap() .improved_by, 2, ); }) } #[test] fn check_obsolete_submit_finality_proof_ignores_other_calls() { run_test(|| { let call = RuntimeCall::System(frame_system::Call::::remark { remark: vec![42] }); assert_eq!(RuntimeCall::check_obsolete_submit_finality_proof(&call), Ok(None)); }) } }