highperfocused/bitcoin
1
0
Fork 0
mirror of https://github.com/bitcoin/bitcoin.git synced 2025-11-12 23:18:14 +01:00
Code Issues Packages Projects Releases Wiki Activity

Require callers of AcceptBlockHeader() to perform anti-dos checks

Browse Source 
In order to prevent memory DoS, we must ensure that we don't accept a new
header into memory until we've performed anti-DoS checks, such as verifying
that the header is part of a sufficiently high work chain. This commit adds a
new argument to AcceptBlockHeader() so that we can ensure that all call-sites
which might cause a new header to be accepted into memory have to grapple with
the question of whether the header is safe to accept, or needs further
validation.

This patch also fixes two places where low-difficulty-headers could have been
processed without such validation (processing an unrequested block from the
network, and processing a compact block).

Credit to Niklas Gögge for noticing this issue, and thanks to Sjors Provoost
for test code.
This commit is contained in:
Suhas Daftuar
2022-08-02 16:48:57 -04:00
parent 551a8d957c
commit ed6cddd98e
18 changed files with 120 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
src/validation.cpp
View File

@@ -3588,9 +3588,10 @@ static bool ContextualCheckBlock(const CBlock& block, BlockValidationState& stat
return true;
}
bool ChainstateManager::AcceptBlockHeader(const CBlockHeader& block, BlockValidationState& state, CBlockIndex** ppindex)
bool ChainstateManager::AcceptBlockHeader(const CBlockHeader& block, BlockValidationState& state, CBlockIndex** ppindex, bool min_pow_checked)
{
AssertLockHeld(cs_main);
// Check for duplicate
uint256 hash = block.GetHash();
BlockMap::iterator miSelf{m_blockman.m_block_index.find(hash)};
@@ -3668,6 +3669,10 @@ bool ChainstateManager::AcceptBlockHeader(const CBlockHeader& block, BlockValida
}
}
}
if (!min_pow_checked) {
LogPrint(BCLog::VALIDATION, "%s: not adding new block header %s, missing anti-dos proof-of-work validation\n", __func__, hash.ToString());
return state.Invalid(BlockValidationResult::BLOCK_HEADER_LOW_WORK, "too-little-chainwork");
}
CBlockIndex* pindex{m_blockman.AddToBlockIndex(block, m_best_header)};
if (ppindex)
@@ -3677,14 +3682,14 @@ bool ChainstateManager::AcceptBlockHeader(const CBlockHeader& block, BlockValida
}
// Exposed wrapper for AcceptBlockHeader
bool ChainstateManager::ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, BlockValidationState& state, const CBlockIndex** ppindex)
bool ChainstateManager::ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, bool min_pow_checked, BlockValidationState& state, const CBlockIndex** ppindex)
{
AssertLockNotHeld(cs_main);
{
LOCK(cs_main);
for (const CBlockHeader& header : headers) {
CBlockIndex *pindex = nullptr; // Use a temp pindex instead of ppindex to avoid a const_cast
bool accepted{AcceptBlockHeader(header, state, &pindex)};
bool accepted{AcceptBlockHeader(header, state, &pindex, min_pow_checked)};
ActiveChainstate().CheckBlockIndex();
if (!accepted) {
@@ -3707,7 +3712,7 @@ bool ChainstateManager::ProcessNewBlockHeaders(const std::vector<CBlockHeader>&
}
/** Store block on disk. If dbp is non-nullptr, the file is known to already reside on disk */
bool CChainState::AcceptBlock(const std::shared_ptr<const CBlock>& pblock, BlockValidationState& state, CBlockIndex** ppindex, bool fRequested, const FlatFilePos* dbp, bool* fNewBlock)
bool CChainState::AcceptBlock(const std::shared_ptr<const CBlock>& pblock, BlockValidationState& state, CBlockIndex** ppindex, bool fRequested, const FlatFilePos* dbp, bool* fNewBlock, bool min_pow_checked)
{
const CBlock& block = *pblock;
@@ -3717,7 +3722,7 @@ bool CChainState::AcceptBlock(const std::shared_ptr<const CBlock>& pblock, Block
CBlockIndex *pindexDummy = nullptr;
CBlockIndex *&pindex = ppindex ? *ppindex : pindexDummy;
bool accepted_header{m_chainman.AcceptBlockHeader(block, state, &pindex)};
bool accepted_header{m_chainman.AcceptBlockHeader(block, state, &pindex, min_pow_checked)};
CheckBlockIndex();
if (!accepted_header)
@@ -3790,7 +3795,7 @@ bool CChainState::AcceptBlock(const std::shared_ptr<const CBlock>& pblock, Block
return true;
}
bool ChainstateManager::ProcessNewBlock(const std::shared_ptr<const CBlock>& block, bool force_processing, bool* new_block)
bool ChainstateManager::ProcessNewBlock(const std::shared_ptr<const CBlock>& block, bool force_processing, bool min_pow_checked, bool* new_block)
{
AssertLockNotHeld(cs_main);
@@ -3811,7 +3816,7 @@ bool ChainstateManager::ProcessNewBlock(const std::shared_ptr<const CBlock>& blo
bool ret = CheckBlock(*block, state, GetConsensus());
if (ret) {
// Store to disk
ret = ActiveChainstate().AcceptBlock(block, state, &pindex, force_processing, nullptr, new_block);
ret = ActiveChainstate().AcceptBlock(block, state, &pindex, force_processing, nullptr, new_block, min_pow_checked);
}
if (!ret) {
GetMainSignals().BlockChecked(*block, state);
@@ -4348,7 +4353,7 @@ void CChainState::LoadExternalBlockFile(
const CBlockIndex* pindex = m_blockman.LookupBlockIndex(hash);
if (!pindex || (pindex->nStatus & BLOCK_HAVE_DATA) == 0) {
BlockValidationState state;
if (AcceptBlock(pblock, state, nullptr, true, dbp, nullptr)) {
if (AcceptBlock(pblock, state, nullptr, true, dbp, nullptr, true)) {
nLoaded++;
}
if (state.IsError()) {
@@ -4386,7 +4391,7 @@ void CChainState::LoadExternalBlockFile(
head.ToString());
LOCK(cs_main);
BlockValidationState dummy;
if (AcceptBlock(pblockrecursive, dummy, nullptr, true, &it->second, nullptr)) {
if (AcceptBlock(pblockrecursive, dummy, nullptr, true, &it->second, nullptr, true)) {
nLoaded++;
queue.push_back(pblockrecursive->GetHash());
}