1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632
//! Stateless and parallelized block verification that happens before block is imported (except for locally produced
//! blocks that are imported directly).
//!
//! The goal of verifier is to check internal consistency of the block, which includes things like
//! solution according to claimed inputs, signature, Proof of Time checkpoints in justifications,
//! etc.
//!
//! This should be the majority of the block verification computation such that all that is left for
//! [`block_import`](crate::block_import) to check is that information in the block corresponds to
//! the state of the parent block, which for the most part is comparing bytes against known good
//! values.
//!
//! This is a significant tradeoff in the protocol: having a smaller header vs being able to verify
//! a lot of things stateless and in parallel.
use futures::lock::Mutex;
use rand::prelude::*;
use rayon::prelude::*;
use sc_client_api::backend::AuxStore;
use sc_consensus::block_import::BlockImportParams;
use sc_consensus::import_queue::Verifier;
use sc_consensus_slots::check_equivocation;
use sc_proof_of_time::verifier::PotVerifier;
use sc_telemetry::{telemetry, TelemetryHandle, CONSENSUS_TRACE};
use sc_transaction_pool_api::OffchainTransactionPoolFactory;
use schnorrkel::context::SigningContext;
use sp_api::{ApiExt, ProvideRuntimeApi};
use sp_block_builder::BlockBuilder as BlockBuilderApi;
use sp_blockchain::HeaderBackend;
use sp_consensus::BlockOrigin;
use sp_consensus_slots::Slot;
use sp_consensus_subspace::digests::{
extract_subspace_digest_items, CompatibleDigestItem, PreDigest, SubspaceDigestItems,
};
use sp_consensus_subspace::{
ChainConstants, FarmerPublicKey, FarmerSignature, PotNextSlotInput, SubspaceApi,
SubspaceJustification,
};
use sp_runtime::traits::{Block as BlockT, Header as HeaderT, NumberFor};
use sp_runtime::{DigestItem, Justifications};
use std::iter;
use std::marker::PhantomData;
use std::num::NonZeroUsize;
use std::sync::atomic::{AtomicU32, Ordering};
use std::sync::Arc;
use std::thread::available_parallelism;
use subspace_core_primitives::crypto::kzg::Kzg;
use subspace_core_primitives::{BlockNumber, PublicKey, RewardSignature};
use subspace_proof_of_space::Table;
use subspace_verification::{check_reward_signature, verify_solution, VerifySolutionParams};
use tokio::sync::Semaphore;
use tracing::{debug, info, trace, warn};
/// This corresponds to default value of `--max-runtime-instances` in Substrate
const BLOCKS_LIST_CHECK_CONCURRENCY: usize = 8;
/// Errors encountered by the Subspace verification task.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum VerificationError<Header: HeaderT> {
/// Header has a bad seal
#[error("Header {0:?} has a bad seal")]
HeaderBadSeal(Header::Hash),
/// Header is unsealed
#[error("Header {0:?} is unsealed")]
HeaderUnsealed(Header::Hash),
/// Bad reward signature
#[error("Bad reward signature on {0:?}")]
BadRewardSignature(Header::Hash),
/// Missing Subspace justification
#[error("Missing Subspace justification")]
MissingSubspaceJustification,
/// Invalid Subspace justification
#[error("Invalid Subspace justification: {0}")]
InvalidSubspaceJustification(codec::Error),
/// Invalid Subspace justification contents
#[error("Invalid Subspace justification contents")]
InvalidSubspaceJustificationContents,
/// Invalid proof of time
#[error("Invalid proof of time")]
InvalidProofOfTime,
/// Verification error
#[error("Verification error on slot {0:?}: {1:?}")]
VerificationError(Slot, subspace_verification::Error),
}
/// A header which has been checked
struct CheckedHeader<H> {
/// A header which is fully checked, including signature. This is the pre-header accompanied by
/// the seal components.
///
/// Includes the digest item that encoded the seal.
pre_header: H,
/// Pre-digest
pre_digest: PreDigest<FarmerPublicKey, FarmerPublicKey>,
/// Seal (signature)
seal: DigestItem,
}
/// Subspace verification parameters
struct VerificationParams<'a, Header>
where
Header: HeaderT + 'a,
{
/// The header being verified.
header: Header,
/// Parameters for solution verification
verify_solution_params: &'a VerifySolutionParams,
}
/// Options for Subspace block verifier
pub struct SubspaceVerifierOptions<Block, Client, SelectChain>
where
Block: BlockT,
{
/// Substrate client
pub client: Arc<Client>,
/// Subspace chain constants
pub chain_constants: ChainConstants,
/// Kzg instance
pub kzg: Kzg,
/// Chain selection rule
pub select_chain: SelectChain,
/// Telemetry
pub telemetry: Option<TelemetryHandle>,
/// The offchain transaction pool factory.
///
/// Will be used when sending equivocation reports and votes.
pub offchain_tx_pool_factory: OffchainTransactionPoolFactory<Block>,
/// Context for reward signing
pub reward_signing_context: SigningContext,
/// Approximate target block number for syncing purposes
pub sync_target_block_number: Arc<AtomicU32>,
/// Whether this node is authoring blocks
pub is_authoring_blocks: bool,
/// Proof of time verifier
pub pot_verifier: PotVerifier,
}
/// A verifier for Subspace blocks.
pub struct SubspaceVerifier<PosTable, Block, Client, SelectChain>
where
Block: BlockT,
{
client: Arc<Client>,
kzg: Kzg,
select_chain: SelectChain,
telemetry: Option<TelemetryHandle>,
offchain_tx_pool_factory: OffchainTransactionPoolFactory<Block>,
chain_constants: ChainConstants,
reward_signing_context: SigningContext,
sync_target_block_number: Arc<AtomicU32>,
is_authoring_blocks: bool,
pot_verifier: PotVerifier,
equivocation_mutex: Mutex<()>,
block_list_verification_semaphore: Semaphore,
_pos_table: PhantomData<PosTable>,
_block: PhantomData<Block>,
}
impl<PosTable, Block, Client, SelectChain> SubspaceVerifier<PosTable, Block, Client, SelectChain>
where
PosTable: Table,
Block: BlockT,
BlockNumber: From<NumberFor<Block>>,
Client: AuxStore + HeaderBackend<Block> + ProvideRuntimeApi<Block>,
Client::Api: BlockBuilderApi<Block> + SubspaceApi<Block, FarmerPublicKey>,
SelectChain: sp_consensus::SelectChain<Block>,
{
/// Create new instance
pub fn new(options: SubspaceVerifierOptions<Block, Client, SelectChain>) -> Self {
let SubspaceVerifierOptions {
client,
chain_constants,
kzg,
select_chain,
telemetry,
offchain_tx_pool_factory,
reward_signing_context,
sync_target_block_number,
is_authoring_blocks,
pot_verifier,
} = options;
Self {
client,
kzg,
select_chain,
telemetry,
offchain_tx_pool_factory,
chain_constants,
reward_signing_context,
sync_target_block_number,
is_authoring_blocks,
pot_verifier,
equivocation_mutex: Mutex::default(),
block_list_verification_semaphore: Semaphore::new(BLOCKS_LIST_CHECK_CONCURRENCY),
_pos_table: Default::default(),
_block: Default::default(),
}
}
/// Determine if full proof of time verification is needed for this block number
fn full_pot_verification(&self, block_number: NumberFor<Block>) -> bool {
let sync_target_block_number: BlockNumber =
self.sync_target_block_number.load(Ordering::Relaxed);
let Some(diff) = sync_target_block_number.checked_sub(BlockNumber::from(block_number))
else {
return true;
};
let sample_size = match diff {
..=1_581 => {
return true;
}
1_582..=6_234 => 1_581,
6_235..=63_240 => 3_162 * (diff - 3_162) / (diff - 1),
63_241..=3_162_000 => 3_162,
_ => diff / 1_000,
};
let n = thread_rng().gen_range(0..=diff);
n < sample_size
}
/// Check a header has been signed correctly and whether solution is correct. If the slot is too
/// far in the future, an error will be returned. If successful, returns the pre-header and the
/// digest item containing the seal.
///
/// The seal must be the last digest. Otherwise, the whole header is considered unsigned. This
/// is required for security and must not be changed.
///
/// This digest item will always return `Some` when used with `as_subspace_pre_digest`.
///
/// `pre_digest` argument is optional in case it is available to avoid doing the work of
/// extracting it from the header twice.
async fn check_header(
&self,
params: VerificationParams<'_, Block::Header>,
subspace_digest_items: SubspaceDigestItems<
FarmerPublicKey,
FarmerPublicKey,
FarmerSignature,
>,
full_pot_verification: bool,
justifications: &Option<Justifications>,
) -> Result<CheckedHeader<Block::Header>, VerificationError<Block::Header>> {
let VerificationParams {
mut header,
verify_solution_params,
} = params;
let pre_digest = subspace_digest_items.pre_digest;
let slot = pre_digest.slot();
let seal = header
.digest_mut()
.pop()
.ok_or_else(|| VerificationError::HeaderUnsealed(header.hash()))?;
let signature = seal
.as_subspace_seal()
.ok_or_else(|| VerificationError::HeaderBadSeal(header.hash()))?;
// The pre-hash of the header doesn't include the seal and that's what we sign
let pre_hash = header.hash();
// With justifications we can verify PoT checkpoints quickly and efficiently, the only check
// that will remain is to ensure that seed and number of iterations (inputs) is correct
// during block import.
{
let Some(subspace_justification) = justifications
.as_ref()
.and_then(|justifications| {
justifications
.iter()
.find_map(SubspaceJustification::try_from_justification)
})
.transpose()
.map_err(VerificationError::InvalidSubspaceJustification)?
else {
return Err(VerificationError::MissingSubspaceJustification);
};
let SubspaceJustification::PotCheckpoints { seed, checkpoints } =
subspace_justification;
// Last checkpoint must be our future proof of time, this is how we anchor the rest of
// checks together
if checkpoints.last().map(|checkpoints| checkpoints.output())
!= Some(pre_digest.pot_info().future_proof_of_time())
{
return Err(VerificationError::InvalidSubspaceJustificationContents);
}
let future_slot = slot + self.chain_constants.block_authoring_delay();
let first_slot_to_check = Slot::from(
future_slot
.checked_sub(checkpoints.len() as u64 - 1)
.ok_or(VerificationError::InvalidProofOfTime)?,
);
let slot_iterations = subspace_digest_items
.pot_parameters_change
.as_ref()
.and_then(|parameters_change| {
(parameters_change.slot <= first_slot_to_check)
.then_some(parameters_change.slot_iterations)
})
.unwrap_or(subspace_digest_items.pot_slot_iterations);
let mut pot_input = PotNextSlotInput {
slot: first_slot_to_check,
slot_iterations,
seed,
};
// Collect all the data we will use for verification so we can process it in parallel
let checkpoints_verification_input = iter::once((
pot_input,
*checkpoints
.first()
.expect("Not empty, contents was checked above; qed"),
));
let checkpoints_verification_input = checkpoints_verification_input
.chain(checkpoints.windows(2).map(|checkpoints_pair| {
pot_input = PotNextSlotInput::derive(
pot_input.slot_iterations,
pot_input.slot,
checkpoints_pair[0].output(),
&subspace_digest_items.pot_parameters_change,
);
(pot_input, checkpoints_pair[1])
}))
.collect::<Vec<_>>();
// All checkpoints must be valid, at least according to the seed included in
// justifications, search for the first error
let pot_verifier = &self.pot_verifier;
checkpoints_verification_input
.into_par_iter()
.find_map_first(|(pot_input, checkpoints)| {
if full_pot_verification {
// Try to find invalid checkpoints
if !pot_verifier.verify_checkpoints(
pot_input.seed,
pot_input.slot_iterations,
&checkpoints,
) {
return Some(VerificationError::InvalidProofOfTime);
}
} else {
// We inject verified checkpoints in order to avoid full proving when votes
// included in the block will inevitably be verified during block execution
pot_verifier.inject_verified_checkpoints(
pot_input.seed,
pot_input.slot_iterations,
checkpoints,
);
}
// We search for errors
None
})
.map_or(Ok(()), Err)?;
}
// Verify that block is signed properly
if check_reward_signature(
pre_hash.as_ref(),
&RewardSignature::from(&signature),
&PublicKey::from(&pre_digest.solution().public_key),
&self.reward_signing_context,
)
.is_err()
{
return Err(VerificationError::BadRewardSignature(pre_hash));
}
// Verify that solution is valid
verify_solution::<PosTable, _, _>(
pre_digest.solution(),
slot.into(),
verify_solution_params,
&self.kzg,
)
.map_err(|error| VerificationError::VerificationError(slot, error))?;
Ok(CheckedHeader {
pre_header: header,
pre_digest,
seal,
})
}
async fn check_and_report_equivocation(
&self,
slot_now: Slot,
slot: Slot,
header: &Block::Header,
author: &FarmerPublicKey,
origin: &BlockOrigin,
) -> Result<(), String> {
// don't report any equivocations during initial sync
// as they are most likely stale.
if *origin == BlockOrigin::NetworkInitialSync {
return Ok(());
}
// Equivocation verification uses `AuxStore` in a way that is not safe from concurrency,
// this lock ensures that we process one header at a time
let _guard = self.equivocation_mutex.lock().await;
// check if authorship of this header is an equivocation and return a proof if so.
let equivocation_proof =
match check_equivocation(&*self.client, slot_now, slot, header, author)
.map_err(|error| error.to_string())?
{
Some(proof) => proof,
None => return Ok(()),
};
info!(
"Slot author {:?} is equivocating at slot {} with headers {:?} and {:?}",
author,
slot,
equivocation_proof.first_header.hash(),
equivocation_proof.second_header.hash(),
);
if self.is_authoring_blocks {
// get the best block on which we will build and send the equivocation report.
let best_hash = self
.select_chain
.best_chain()
.await
.map(|h| h.hash())
.map_err(|error| error.to_string())?;
// submit equivocation report at best block.
let mut runtime_api = self.client.runtime_api();
// Register the offchain tx pool to be able to use it from the runtime.
runtime_api.register_extension(
self.offchain_tx_pool_factory
.offchain_transaction_pool(best_hash),
);
runtime_api
.submit_report_equivocation_extrinsic(best_hash, equivocation_proof)
.map_err(|error| error.to_string())?;
info!(%author, "Submitted equivocation report for author");
} else {
info!("Not submitting equivocation report because node is not authoring blocks");
}
Ok(())
}
}
#[async_trait::async_trait]
impl<PosTable, Block, Client, SelectChain> Verifier<Block>
for SubspaceVerifier<PosTable, Block, Client, SelectChain>
where
PosTable: Table,
Block: BlockT,
BlockNumber: From<NumberFor<Block>>,
Client: HeaderBackend<Block> + ProvideRuntimeApi<Block> + Send + Sync + AuxStore,
Client::Api: BlockBuilderApi<Block> + SubspaceApi<Block, FarmerPublicKey>,
SelectChain: sp_consensus::SelectChain<Block>,
{
fn verification_concurrency(&self) -> NonZeroUsize {
available_parallelism().unwrap_or(NonZeroUsize::new(1).expect("Not zero; qed"))
}
async fn verify(
&self,
mut block: BlockImportParams<Block>,
) -> Result<BlockImportParams<Block>, String> {
trace!(
origin = ?block.origin,
header = ?block.header,
justifications = ?block.justifications,
body = ?block.body,
"Verifying",
);
let best_number = self.client.info().best_number;
// Reject block below archiving point, but only if we received it from the network
if *block.header.number() + self.chain_constants.confirmation_depth_k().into() < best_number
&& matches!(block.origin, BlockOrigin::NetworkBroadcast)
{
debug!(
header = ?block.header,
%best_number,
"Rejecting block below archiving point"
);
return Err(format!(
"Rejecting block #{} below archiving point",
block.header.number()
));
}
let hash = block.header.hash();
debug!(
"We have {:?} logs in this header",
block.header.digest().logs().len()
);
let subspace_digest_items = extract_subspace_digest_items::<
Block::Header,
FarmerPublicKey,
FarmerPublicKey,
FarmerSignature,
>(&block.header)?;
// Check if farmer's plot is burned, ignore runtime API errors since this check will happen
// during block import anyway
{
// We need to limit number of threads to avoid running out of WASM instances
let _permit = self
.block_list_verification_semaphore
.acquire()
.await
.expect("Never closed; qed");
if self
.client
.runtime_api()
.is_in_block_list(
*block.header.parent_hash(),
&subspace_digest_items.pre_digest.solution().public_key,
)
.unwrap_or_default()
{
warn!(
public_key = %subspace_digest_items.pre_digest.solution().public_key,
"Verifying block with solution provided by farmer in block list"
);
return Err(format!(
"Farmer {} is in block list",
subspace_digest_items
.pre_digest
.solution()
.public_key
.clone(),
));
}
}
let full_pot_verification = self.full_pot_verification(*block.header.number());
// Stateless header verification only. This means only check that header contains required
// contents, correct signature and valid Proof-of-Space, but because previous block is not
// guaranteed to be imported at this point, it is not possible to verify
// Proof-of-Archival-Storage. In order to verify PoAS randomness and solution range
// from the header are checked against expected correct values during block import as well
// as whether piece in the header corresponds to the actual archival history of the
// blockchain.
let checked_header = self
.check_header(
VerificationParams {
header: block.header.clone(),
verify_solution_params: &VerifySolutionParams {
proof_of_time: subspace_digest_items.pre_digest.pot_info().proof_of_time(),
solution_range: subspace_digest_items.solution_range,
piece_check_params: None,
},
},
subspace_digest_items,
full_pot_verification,
&block.justifications,
)
.await
.map_err(|error| error.to_string())?;
let CheckedHeader {
pre_header,
pre_digest,
seal,
} = checked_header;
let slot = pre_digest.slot();
// Estimate what the "current" slot is according to sync target since we don't have other
// way to know it
let diff_in_blocks = self
.sync_target_block_number
.load(Ordering::Relaxed)
.saturating_sub(BlockNumber::from(*pre_header.number()));
let slot_now = if diff_in_blocks > 0 {
slot + Slot::from(
u64::from(diff_in_blocks) * self.chain_constants.slot_probability().1
/ self.chain_constants.slot_probability().0,
)
} else {
slot
};
// the header is valid but let's check if there was something else already proposed at the
// same slot by the given author. if there was, we will report the equivocation to the
// runtime.
if let Err(error) = self
.check_and_report_equivocation(
slot_now,
slot,
&block.header,
&pre_digest.solution().public_key,
&block.origin,
)
.await
{
warn!(
%error,
"Error checking/reporting Subspace equivocation"
);
}
trace!(?pre_header, "Checked header; importing");
telemetry!(
self.telemetry;
CONSENSUS_TRACE;
"subspace.checked_and_importing";
"pre_header" => ?pre_header,
);
block.header = pre_header;
block.post_digests.push(seal);
block.post_hash = Some(hash);
Ok(block)
}
}