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-rw-r--r--src/net_processing.cpp12
-rw-r--r--src/primitives/block.h8
-rw-r--r--src/test/validation_tests.cpp216
-rw-r--r--src/validation.cpp127
-rw-r--r--src/validation.h3
-rw-r--r--src/wallet/wallet.cpp4
6 files changed, 328 insertions, 42 deletions
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index d48a118dd6..43e15487f3 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -4629,6 +4629,17 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
LogPrint(BCLog::NET, "received block %s peer=%d\n", pblock->GetHash().ToString(), pfrom.GetId());
+ const CBlockIndex* prev_block{WITH_LOCK(m_chainman.GetMutex(), return m_chainman.m_blockman.LookupBlockIndex(pblock->hashPrevBlock))};
+
+ // Check for possible mutation if it connects to something we know so we can check for DEPLOYMENT_SEGWIT being active
+ if (prev_block && IsBlockMutated(/*block=*/*pblock,
+ /*check_witness_root=*/DeploymentActiveAfter(prev_block, m_chainman, Consensus::DEPLOYMENT_SEGWIT))) {
+ LogPrint(BCLog::NET, "Received mutated block from peer=%d\n", peer->m_id);
+ Misbehaving(*peer, 100, "mutated block");
+ WITH_LOCK(cs_main, RemoveBlockRequest(pblock->GetHash(), peer->m_id));
+ return;
+ }
+
bool forceProcessing = false;
const uint256 hash(pblock->GetHash());
bool min_pow_checked = false;
@@ -4644,7 +4655,6 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
mapBlockSource.emplace(hash, std::make_pair(pfrom.GetId(), true));
// Check work on this block against our anti-dos thresholds.
- const CBlockIndex* prev_block = m_chainman.m_blockman.LookupBlockIndex(pblock->hashPrevBlock);
if (prev_block && prev_block->nChainWork + CalculateHeadersWork({pblock->GetBlockHeader()}) >= GetAntiDoSWorkThreshold()) {
min_pow_checked = true;
}
diff --git a/src/primitives/block.h b/src/primitives/block.h
index bd11279a6e..6117c477f8 100644
--- a/src/primitives/block.h
+++ b/src/primitives/block.h
@@ -71,8 +71,10 @@ public:
// network and disk
std::vector<CTransactionRef> vtx;
- // memory only
- mutable bool fChecked;
+ // Memory-only flags for caching expensive checks
+ mutable bool fChecked; // CheckBlock()
+ mutable bool m_checked_witness_commitment{false}; // CheckWitnessCommitment()
+ mutable bool m_checked_merkle_root{false}; // CheckMerkleRoot()
CBlock()
{
@@ -96,6 +98,8 @@ public:
CBlockHeader::SetNull();
vtx.clear();
fChecked = false;
+ m_checked_witness_commitment = false;
+ m_checked_merkle_root = false;
}
CBlockHeader GetBlockHeader() const
diff --git a/src/test/validation_tests.cpp b/src/test/validation_tests.cpp
index 0b4c491615..c9b9671671 100644
--- a/src/test/validation_tests.cpp
+++ b/src/test/validation_tests.cpp
@@ -4,11 +4,16 @@
#include <chainparams.h>
#include <consensus/amount.h>
+#include <consensus/merkle.h>
+#include <core_io.h>
+#include <hash.h>
#include <net.h>
#include <signet.h>
#include <uint256.h>
#include <validation.h>
+#include <string>
+
#include <test/util/setup_common.h>
#include <boost/test/unit_test.hpp>
@@ -144,4 +149,215 @@ BOOST_AUTO_TEST_CASE(test_assumeutxo)
BOOST_CHECK_EQUAL(out210.nChainTx, 200U);
}
+BOOST_AUTO_TEST_CASE(block_malleation)
+{
+ // Test utilities that calls `IsBlockMutated` and then clears the validity
+ // cache flags on `CBlock`.
+ auto is_mutated = [](CBlock& block, bool check_witness_root) {
+ bool mutated{IsBlockMutated(block, check_witness_root)};
+ block.fChecked = false;
+ block.m_checked_witness_commitment = false;
+ block.m_checked_merkle_root = false;
+ return mutated;
+ };
+ auto is_not_mutated = [&is_mutated](CBlock& block, bool check_witness_root) {
+ return !is_mutated(block, check_witness_root);
+ };
+
+ // Test utilities to create coinbase transactions and insert witness
+ // commitments.
+ //
+ // Note: this will not include the witness stack by default to avoid
+ // triggering the "no witnesses allowed for blocks that don't commit to
+ // witnesses" rule when testing other malleation vectors.
+ auto create_coinbase_tx = [](bool include_witness = false) {
+ CMutableTransaction coinbase;
+ coinbase.vin.resize(1);
+ if (include_witness) {
+ coinbase.vin[0].scriptWitness.stack.resize(1);
+ coinbase.vin[0].scriptWitness.stack[0] = std::vector<unsigned char>(32, 0x00);
+ }
+
+ coinbase.vout.resize(1);
+ coinbase.vout[0].scriptPubKey.resize(MINIMUM_WITNESS_COMMITMENT);
+ coinbase.vout[0].scriptPubKey[0] = OP_RETURN;
+ coinbase.vout[0].scriptPubKey[1] = 0x24;
+ coinbase.vout[0].scriptPubKey[2] = 0xaa;
+ coinbase.vout[0].scriptPubKey[3] = 0x21;
+ coinbase.vout[0].scriptPubKey[4] = 0xa9;
+ coinbase.vout[0].scriptPubKey[5] = 0xed;
+
+ auto tx = MakeTransactionRef(coinbase);
+ assert(tx->IsCoinBase());
+ return tx;
+ };
+ auto insert_witness_commitment = [](CBlock& block, uint256 commitment) {
+ assert(!block.vtx.empty() && block.vtx[0]->IsCoinBase() && !block.vtx[0]->vout.empty());
+
+ CMutableTransaction mtx{*block.vtx[0]};
+ CHash256().Write(commitment).Write(std::vector<unsigned char>(32, 0x00)).Finalize(commitment);
+ memcpy(&mtx.vout[0].scriptPubKey[6], commitment.begin(), 32);
+ block.vtx[0] = MakeTransactionRef(mtx);
+ };
+
+ {
+ CBlock block;
+
+ // Empty block is expected to have merkle root of 0x0.
+ BOOST_CHECK(block.vtx.empty());
+ block.hashMerkleRoot = uint256{1};
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/false));
+ block.hashMerkleRoot = uint256{};
+ BOOST_CHECK(is_not_mutated(block, /*check_witness_root=*/false));
+
+ // Block with a single coinbase tx is mutated if the merkle root is not
+ // equal to the coinbase tx's hash.
+ block.vtx.push_back(create_coinbase_tx());
+ BOOST_CHECK(block.vtx[0]->GetHash() != block.hashMerkleRoot);
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/false));
+ block.hashMerkleRoot = block.vtx[0]->GetHash();
+ BOOST_CHECK(is_not_mutated(block, /*check_witness_root=*/false));
+
+ // Block with two transactions is mutated if the merkle root does not
+ // match the double sha256 of the concatenation of the two transaction
+ // hashes.
+ block.vtx.push_back(MakeTransactionRef(CMutableTransaction{}));
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/false));
+ HashWriter hasher;
+ hasher.write(Span(reinterpret_cast<const std::byte*>(block.vtx[0]->GetHash().data()), 32));
+ hasher.write(Span(reinterpret_cast<const std::byte*>(block.vtx[1]->GetHash().data()), 32));
+ block.hashMerkleRoot = hasher.GetHash();
+ BOOST_CHECK(is_not_mutated(block, /*check_witness_root=*/false));
+
+ // Block with two transactions is mutated if any node is duplicate.
+ {
+ block.vtx[1] = block.vtx[0];
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/false));
+ HashWriter hasher;
+ hasher.write(Span(reinterpret_cast<const std::byte*>(block.vtx[0]->GetHash().data()), 32));
+ hasher.write(Span(reinterpret_cast<const std::byte*>(block.vtx[1]->GetHash().data()), 32));
+ block.hashMerkleRoot = hasher.GetHash();
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/false));
+ }
+
+ // Blocks with 64-byte coinbase transactions are not considered mutated
+ block.vtx.clear();
+ {
+ CMutableTransaction mtx;
+ mtx.vin.resize(1);
+ mtx.vout.resize(1);
+ mtx.vout[0].scriptPubKey.resize(4);
+ block.vtx.push_back(MakeTransactionRef(mtx));
+ block.hashMerkleRoot = block.vtx.back()->GetHash();
+ assert(block.vtx.back()->IsCoinBase());
+ assert(GetSerializeSize(block.vtx.back(), PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) == 64);
+ }
+ BOOST_CHECK(is_not_mutated(block, /*check_witness_root=*/false));
+ }
+
+ {
+ // Test merkle root malleation
+
+ // Pseudo code to mine transactions tx{1,2,3}:
+ //
+ // ```
+ // loop {
+ // tx1 = random_tx()
+ // tx2 = random_tx()
+ // tx3 = deserialize_tx(txid(tx1) || txid(tx2));
+ // if serialized_size_without_witness(tx3) == 64 {
+ // print(hex(tx3))
+ // break
+ // }
+ // }
+ // ```
+ //
+ // The `random_tx` function used to mine the txs below simply created
+ // empty transactions with a random version field.
+ CMutableTransaction tx1;
+ BOOST_CHECK(DecodeHexTx(tx1, "ff204bd0000000000000", /*try_no_witness=*/true, /*try_witness=*/false));
+ CMutableTransaction tx2;
+ BOOST_CHECK(DecodeHexTx(tx2, "8ae53c92000000000000", /*try_no_witness=*/true, /*try_witness=*/false));
+ CMutableTransaction tx3;
+ BOOST_CHECK(DecodeHexTx(tx3, "cdaf22d00002c6a7f848f8ae4d30054e61dcf3303d6fe01d282163341f06feecc10032b3160fcab87bdfe3ecfb769206ef2d991b92f8a268e423a6ef4d485f06", /*try_no_witness=*/true, /*try_witness=*/false));
+ {
+ // Verify that double_sha256(txid1||txid2) == txid3
+ HashWriter hasher;
+ hasher.write(Span(reinterpret_cast<const std::byte*>(tx1.GetHash().data()), 32));
+ hasher.write(Span(reinterpret_cast<const std::byte*>(tx2.GetHash().data()), 32));
+ assert(hasher.GetHash() == tx3.GetHash());
+ // Verify that tx3 is 64 bytes in size (without witness).
+ assert(GetSerializeSize(tx3, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) == 64);
+ }
+
+ CBlock block;
+ block.vtx.push_back(MakeTransactionRef(tx1));
+ block.vtx.push_back(MakeTransactionRef(tx2));
+ uint256 merkle_root = block.hashMerkleRoot = BlockMerkleRoot(block);
+ BOOST_CHECK(is_not_mutated(block, /*check_witness_root=*/false));
+
+ // Mutate the block by replacing the two transactions with one 64-byte
+ // transaction that serializes into the concatenation of the txids of
+ // the transactions in the unmutated block.
+ block.vtx.clear();
+ block.vtx.push_back(MakeTransactionRef(tx3));
+ BOOST_CHECK(!block.vtx.back()->IsCoinBase());
+ BOOST_CHECK(BlockMerkleRoot(block) == merkle_root);
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/false));
+ }
+
+ {
+ CBlock block;
+ block.vtx.push_back(create_coinbase_tx(/*include_witness=*/true));
+ {
+ CMutableTransaction mtx;
+ mtx.vin.resize(1);
+ mtx.vin[0].scriptWitness.stack.resize(1);
+ mtx.vin[0].scriptWitness.stack[0] = {0};
+ block.vtx.push_back(MakeTransactionRef(mtx));
+ }
+ block.hashMerkleRoot = BlockMerkleRoot(block);
+ // Block with witnesses is considered mutated if the witness commitment
+ // is not validated.
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/false));
+ // Block with invalid witness commitment is considered mutated.
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/true));
+
+ // Block with valid commitment is not mutated
+ {
+ auto commitment{BlockWitnessMerkleRoot(block)};
+ insert_witness_commitment(block, commitment);
+ block.hashMerkleRoot = BlockMerkleRoot(block);
+ }
+ BOOST_CHECK(is_not_mutated(block, /*check_witness_root=*/true));
+
+ // Malleating witnesses should be caught by `IsBlockMutated`.
+ {
+ CMutableTransaction mtx{*block.vtx[1]};
+ assert(!mtx.vin[0].scriptWitness.stack[0].empty());
+ ++mtx.vin[0].scriptWitness.stack[0][0];
+ block.vtx[1] = MakeTransactionRef(mtx);
+ }
+ // Without also updating the witness commitment, the merkle root should
+ // not change when changing one of the witnesses.
+ BOOST_CHECK(block.hashMerkleRoot == BlockMerkleRoot(block));
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/true));
+ {
+ auto commitment{BlockWitnessMerkleRoot(block)};
+ insert_witness_commitment(block, commitment);
+ block.hashMerkleRoot = BlockMerkleRoot(block);
+ }
+ BOOST_CHECK(is_not_mutated(block, /*check_witness_root=*/true));
+
+ // Test malleating the coinbase witness reserved value
+ {
+ CMutableTransaction mtx{*block.vtx[0]};
+ mtx.vin[0].scriptWitness.stack.resize(0);
+ block.vtx[0] = MakeTransactionRef(mtx);
+ block.hashMerkleRoot = BlockMerkleRoot(block);
+ }
+ BOOST_CHECK(is_mutated(block, /*check_witness_root=*/true));
+ }
+}
+
BOOST_AUTO_TEST_SUITE_END()
diff --git a/src/validation.cpp b/src/validation.cpp
index 1fd8f0e326..5ef371b97b 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3486,6 +3486,60 @@ static bool CheckBlockHeader(const CBlockHeader& block, BlockValidationState& st
return true;
}
+static bool CheckMerkleRoot(const CBlock& block, BlockValidationState& state)
+{
+ if (block.m_checked_merkle_root) return true;
+
+ bool mutated;
+ uint256 hashMerkleRoot2 = BlockMerkleRoot(block, &mutated);
+ if (block.hashMerkleRoot != hashMerkleRoot2)
+ return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-txnmrklroot", "hashMerkleRoot mismatch");
+
+ // Check for merkle tree malleability (CVE-2012-2459): repeating sequences
+ // of transactions in a block without affecting the merkle root of a block,
+ // while still invalidating it.
+ if (mutated)
+ return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-txns-duplicate", "duplicate transaction");
+
+ block.m_checked_merkle_root = true;
+ return true;
+}
+
+static bool CheckWitnessMalleation(const CBlock& block, bool expect_witness_commitment, BlockValidationState& state)
+{
+ if (expect_witness_commitment) {
+ if (block.m_checked_witness_commitment) return true;
+
+ int commitpos = GetWitnessCommitmentIndex(block);
+ if (commitpos != NO_WITNESS_COMMITMENT) {
+ bool malleated = false;
+ uint256 hashWitness = BlockWitnessMerkleRoot(block, &malleated);
+ // The malleation check is ignored; as the transaction tree itself
+ // already does not permit it, it is impossible to trigger in the
+ // witness tree.
+ if (block.vtx[0]->vin[0].scriptWitness.stack.size() != 1 || block.vtx[0]->vin[0].scriptWitness.stack[0].size() != 32) {
+ return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-witness-nonce-size", strprintf("%s : invalid witness reserved value size", __func__));
+ }
+ CHash256().Write(hashWitness).Write(block.vtx[0]->vin[0].scriptWitness.stack[0]).Finalize(hashWitness);
+ if (memcmp(hashWitness.begin(), &block.vtx[0]->vout[commitpos].scriptPubKey[6], 32)) {
+ return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-witness-merkle-match", strprintf("%s : witness merkle commitment mismatch", __func__));
+ }
+
+ block.m_checked_witness_commitment = true;
+ return true;
+ }
+ }
+
+ // No witness data is allowed in blocks that don't commit to witness data, as this would otherwise leave room for spam
+ for (const auto& tx : block.vtx) {
+ if (tx->HasWitness()) {
+ return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "unexpected-witness", strprintf("%s : unexpected witness data found", __func__));
+ }
+ }
+
+ return true;
+}
+
bool CheckBlock(const CBlock& block, BlockValidationState& state, const Consensus::Params& consensusParams, bool fCheckPOW, bool fCheckMerkleRoot)
{
// These are checks that are independent of context.
@@ -3504,17 +3558,8 @@ bool CheckBlock(const CBlock& block, BlockValidationState& state, const Consensu
}
// Check the merkle root.
- if (fCheckMerkleRoot) {
- bool mutated;
- uint256 hashMerkleRoot2 = BlockMerkleRoot(block, &mutated);
- if (block.hashMerkleRoot != hashMerkleRoot2)
- return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-txnmrklroot", "hashMerkleRoot mismatch");
-
- // Check for merkle tree malleability (CVE-2012-2459): repeating sequences
- // of transactions in a block without affecting the merkle root of a block,
- // while still invalidating it.
- if (mutated)
- return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-txns-duplicate", "duplicate transaction");
+ if (fCheckMerkleRoot && !CheckMerkleRoot(block, state)) {
+ return false;
}
// All potential-corruption validation must be done before we do any
@@ -3605,6 +3650,37 @@ bool HasValidProofOfWork(const std::vector<CBlockHeader>& headers, const Consens
[&](const auto& header) { return CheckProofOfWork(header.GetHash(), header.nBits, consensusParams);});
}
+bool IsBlockMutated(const CBlock& block, bool check_witness_root)
+{
+ BlockValidationState state;
+ if (!CheckMerkleRoot(block, state)) {
+ LogPrint(BCLog::VALIDATION, "Block mutated: %s\n", state.ToString());
+ return true;
+ }
+
+ if (block.vtx.empty() || !block.vtx[0]->IsCoinBase()) {
+ // Consider the block mutated if any transaction is 64 bytes in size (see 3.1
+ // in "Weaknesses in Bitcoin’s Merkle Root Construction":
+ // https://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20190225/a27d8837/attachment-0001.pdf).
+ //
+ // Note: This is not a consensus change as this only applies to blocks that
+ // don't have a coinbase transaction and would therefore already be invalid.
+ return std::any_of(block.vtx.begin(), block.vtx.end(),
+ [](auto& tx) { return ::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) == 64; });
+ } else {
+ // Theoretically it is still possible for a block with a 64 byte
+ // coinbase transaction to be mutated but we neglect that possibility
+ // here as it requires at least 224 bits of work.
+ }
+
+ if (!CheckWitnessMalleation(block, check_witness_root, state)) {
+ LogPrint(BCLog::VALIDATION, "Block mutated: %s\n", state.ToString());
+ return true;
+ }
+
+ return false;
+}
+
arith_uint256 CalculateHeadersWork(const std::vector<CBlockHeader>& headers)
{
arith_uint256 total_work{0};
@@ -3713,33 +3789,8 @@ static bool ContextualCheckBlock(const CBlock& block, BlockValidationState& stat
// * There must be at least one output whose scriptPubKey is a single 36-byte push, the first 4 bytes of which are
// {0xaa, 0x21, 0xa9, 0xed}, and the following 32 bytes are SHA256^2(witness root, witness reserved value). In case there are
// multiple, the last one is used.
- bool fHaveWitness = false;
- if (DeploymentActiveAfter(pindexPrev, chainman, Consensus::DEPLOYMENT_SEGWIT)) {
- int commitpos = GetWitnessCommitmentIndex(block);
- if (commitpos != NO_WITNESS_COMMITMENT) {
- bool malleated = false;
- uint256 hashWitness = BlockWitnessMerkleRoot(block, &malleated);
- // The malleation check is ignored; as the transaction tree itself
- // already does not permit it, it is impossible to trigger in the
- // witness tree.
- if (block.vtx[0]->vin[0].scriptWitness.stack.size() != 1 || block.vtx[0]->vin[0].scriptWitness.stack[0].size() != 32) {
- return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-witness-nonce-size", strprintf("%s : invalid witness reserved value size", __func__));
- }
- CHash256().Write(hashWitness).Write(block.vtx[0]->vin[0].scriptWitness.stack[0]).Finalize(hashWitness);
- if (memcmp(hashWitness.begin(), &block.vtx[0]->vout[commitpos].scriptPubKey[6], 32)) {
- return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "bad-witness-merkle-match", strprintf("%s : witness merkle commitment mismatch", __func__));
- }
- fHaveWitness = true;
- }
- }
-
- // No witness data is allowed in blocks that don't commit to witness data, as this would otherwise leave room for spam
- if (!fHaveWitness) {
- for (const auto& tx : block.vtx) {
- if (tx->HasWitness()) {
- return state.Invalid(BlockValidationResult::BLOCK_MUTATED, "unexpected-witness", strprintf("%s : unexpected witness data found", __func__));
- }
- }
+ if (!CheckWitnessMalleation(block, DeploymentActiveAfter(pindexPrev, chainman, Consensus::DEPLOYMENT_SEGWIT), state)) {
+ return false;
}
// After the coinbase witness reserved value and commitment are verified,
diff --git a/src/validation.h b/src/validation.h
index fd0e2115f7..b6e2e66a44 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -352,6 +352,9 @@ bool TestBlockValidity(BlockValidationState& state,
/** Check with the proof of work on each blockheader matches the value in nBits */
bool HasValidProofOfWork(const std::vector<CBlockHeader>& headers, const Consensus::Params& consensusParams);
+/** Check if a block has been mutated (with respect to its merkle root and witness commitments). */
+bool IsBlockMutated(const CBlock& block, bool check_witness_root);
+
/** Return the sum of the work on a given set of headers */
arith_uint256 CalculateHeadersWork(const std::vector<CBlockHeader>& headers);
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 0d664a4539..e6276d7f78 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2596,8 +2596,10 @@ util::Result<CTxDestination> ReserveDestination::GetReservedDestination(bool int
if (nIndex == -1) {
CKeyPool keypool;
- auto op_address = m_spk_man->GetReservedDestination(type, internal, nIndex, keypool);
+ int64_t index;
+ auto op_address = m_spk_man->GetReservedDestination(type, internal, index, keypool);
if (!op_address) return op_address;
+ nIndex = index;
address = *op_address;
fInternal = keypool.fInternal;
}
generated by cgit v1.2.3 (git 2.26.2) at 2024-11-28 12:16:26 +0000