Disconnect outbound peers relaying invalid headers
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parent
4637f18522
commit
37886d5e2f
3 changed files with 56 additions and 12 deletions
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@ -1205,7 +1205,7 @@ inline void static SendBlockTransactions(const CBlock& block, const BlockTransac
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connman->PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCKTXN, resp));
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}
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bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::vector<CBlockHeader>& headers, const CChainParams& chainparams)
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bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::vector<CBlockHeader>& headers, const CChainParams& chainparams, bool punish_duplicate_invalid)
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{
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const CNetMsgMaker msgMaker(pfrom->GetSendVersion());
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size_t nCount = headers.size();
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@ -1258,13 +1258,48 @@ bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::ve
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}
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CValidationState state;
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if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast)) {
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CBlockHeader first_invalid_header;
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if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast, &first_invalid_header)) {
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int nDoS;
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if (state.IsInvalid(nDoS)) {
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if (nDoS > 0) {
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LOCK(cs_main);
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Misbehaving(pfrom->GetId(), nDoS);
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}
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if (punish_duplicate_invalid && mapBlockIndex.find(first_invalid_header.GetHash()) != mapBlockIndex.end()) {
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// Goal: don't allow outbound peers to use up our outbound
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// connection slots if they are on incompatible chains.
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//
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// We ask the caller to set punish_invalid appropriately based
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// on the peer and the method of header delivery (compact
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// blocks are allowed to be invalid in some circumstances,
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// under BIP 152).
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// Here, we try to detect the narrow situation that we have a
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// valid block header (ie it was valid at the time the header
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// was received, and hence stored in mapBlockIndex) but know the
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// block is invalid, and that a peer has announced that same
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// block as being on its active chain.
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// Disconnect the peer in such a situation.
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//
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// Note: if the header that is invalid was not accepted to our
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// mapBlockIndex at all, that may also be grounds for
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// disconnecting the peer, as the chain they are on is likely
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// to be incompatible. However, there is a circumstance where
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// that does not hold: if the header's timestamp is more than
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// 2 hours ahead of our current time. In that case, the header
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// may become valid in the future, and we don't want to
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// disconnect a peer merely for serving us one too-far-ahead
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// block header, to prevent an attacker from splitting the
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// network by mining a block right at the 2 hour boundary.
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//
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// TODO: update the DoS logic (or, rather, rewrite the
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// DoS-interface between validation and net_processing) so that
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// the interface is cleaner, and so that we disconnect on all the
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// reasons that a peer's headers chain is incompatible
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// with ours (eg block->nVersion softforks, MTP violations,
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// etc), and not just the duplicate-invalid case.
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pfrom->fDisconnect = true;
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}
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return error("invalid header received");
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}
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}
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@ -2219,7 +2254,6 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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// If we end up treating this as a plain headers message, call that as well
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// without cs_main.
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bool fRevertToHeaderProcessing = false;
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CDataStream vHeadersMsg(SER_NETWORK, PROTOCOL_VERSION);
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// Keep a CBlock for "optimistic" compactblock reconstructions (see
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// below)
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@ -2336,10 +2370,6 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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return true;
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} else {
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// If this was an announce-cmpctblock, we want the same treatment as a header message
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// Dirty hack to process as if it were just a headers message (TODO: move message handling into their own functions)
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std::vector<CBlock> headers;
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headers.push_back(cmpctblock.header);
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vHeadersMsg << headers;
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fRevertToHeaderProcessing = true;
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}
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}
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@ -2348,8 +2378,14 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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if (fProcessBLOCKTXN)
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return ProcessMessage(pfrom, NetMsgType::BLOCKTXN, blockTxnMsg, nTimeReceived, chainparams, connman, interruptMsgProc);
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if (fRevertToHeaderProcessing)
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return ProcessMessage(pfrom, NetMsgType::HEADERS, vHeadersMsg, nTimeReceived, chainparams, connman, interruptMsgProc);
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if (fRevertToHeaderProcessing) {
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// Headers received from HB compact block peers are permitted to be
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// relayed before full validation (see BIP 152), so we don't want to disconnect
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// the peer if the header turns out to be for an invalid block.
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// Note that if a peer tries to build on an invalid chain, that
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// will be detected and the peer will be banned.
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return ProcessHeadersMessage(pfrom, connman, {cmpctblock.header}, chainparams, /*punish_duplicate_invalid=*/false);
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}
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if (fBlockReconstructed) {
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// If we got here, we were able to optimistically reconstruct a
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@ -2480,7 +2516,12 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
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ReadCompactSize(vRecv); // ignore tx count; assume it is 0.
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}
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return ProcessHeadersMessage(pfrom, connman, headers, chainparams);
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// Headers received via a HEADERS message should be valid, and reflect
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// the chain the peer is on. If we receive a known-invalid header,
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// disconnect the peer if it is using one of our outbound connection
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// slots.
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bool should_punish = !pfrom->fInbound && !pfrom->m_manual_connection;
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return ProcessHeadersMessage(pfrom, connman, headers, chainparams, should_punish);
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}
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else if (strCommand == NetMsgType::BLOCK && !fImporting && !fReindex) // Ignore blocks received while importing
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@ -3079,13 +3079,15 @@ static bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state
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}
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// Exposed wrapper for AcceptBlockHeader
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bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex)
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bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex, CBlockHeader *first_invalid)
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{
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if (first_invalid != nullptr) first_invalid->SetNull();
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{
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LOCK(cs_main);
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for (const CBlockHeader& header : headers) {
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CBlockIndex *pindex = nullptr; // Use a temp pindex instead of ppindex to avoid a const_cast
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if (!AcceptBlockHeader(header, state, chainparams, &pindex)) {
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if (first_invalid) *first_invalid = header;
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return false;
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}
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if (ppindex) {
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@ -247,8 +247,9 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
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* @param[out] state This may be set to an Error state if any error occurred processing them
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* @param[in] chainparams The params for the chain we want to connect to
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* @param[out] ppindex If set, the pointer will be set to point to the last new block index object for the given headers
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* @param[out] first_invalid First header that fails validation, if one exists
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*/
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bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& block, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex=nullptr);
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bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& block, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex=nullptr, CBlockHeader *first_invalid=nullptr);
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/** Check whether enough disk space is available for an incoming block */
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bool CheckDiskSpace(uint64_t nAdditionalBytes = 0);
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