[Pkg-bitcoin-commits] [bitcoin] 98/126: Disconnect outbound peers relaying invalid headers
Jonas Smedegaard
dr at jones.dk
Mon Nov 13 20:02:58 UTC 2017
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js pushed a commit to annotated tag debian/0.15.1_dfsg-1
in repository bitcoin.
commit 59b210d9a7fec79afba07d2ea90b190ce1d74209
Author: Suhas Daftuar <sdaftuar at gmail.com>
Date: Thu Oct 26 14:54:33 2017 -0400
Disconnect outbound peers relaying invalid headers
Github-Pull: #11568
Rebased-From: 37886d5e2f9992678dea4b1bd893f4f10d61d3ad
---
src/net_processing.cpp | 61 +++++++++++++++++++++++++++++++++++++++++---------
src/validation.cpp | 4 +++-
src/validation.h | 3 ++-
3 files changed, 56 insertions(+), 12 deletions(-)
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index eac2853..f677915 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1193,7 +1193,7 @@ inline void static SendBlockTransactions(const CBlock& block, const BlockTransac
connman->PushMessage(pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCKTXN, resp));
}
-bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::vector<CBlockHeader>& headers, const CChainParams& chainparams)
+bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::vector<CBlockHeader>& headers, const CChainParams& chainparams, bool punish_duplicate_invalid)
{
const CNetMsgMaker msgMaker(pfrom->GetSendVersion());
size_t nCount = headers.size();
@@ -1246,13 +1246,48 @@ bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::ve
}
CValidationState state;
- if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast)) {
+ CBlockHeader first_invalid_header;
+ if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast, &first_invalid_header)) {
int nDoS;
if (state.IsInvalid(nDoS)) {
if (nDoS > 0) {
LOCK(cs_main);
Misbehaving(pfrom->GetId(), nDoS);
}
+ if (punish_duplicate_invalid && mapBlockIndex.find(first_invalid_header.GetHash()) != mapBlockIndex.end()) {
+ // Goal: don't allow outbound peers to use up our outbound
+ // connection slots if they are on incompatible chains.
+ //
+ // We ask the caller to set punish_invalid appropriately based
+ // on the peer and the method of header delivery (compact
+ // blocks are allowed to be invalid in some circumstances,
+ // under BIP 152).
+ // Here, we try to detect the narrow situation that we have a
+ // valid block header (ie it was valid at the time the header
+ // was received, and hence stored in mapBlockIndex) but know the
+ // block is invalid, and that a peer has announced that same
+ // block as being on its active chain.
+ // Disconnect the peer in such a situation.
+ //
+ // Note: if the header that is invalid was not accepted to our
+ // mapBlockIndex at all, that may also be grounds for
+ // disconnecting the peer, as the chain they are on is likely
+ // to be incompatible. However, there is a circumstance where
+ // that does not hold: if the header's timestamp is more than
+ // 2 hours ahead of our current time. In that case, the header
+ // may become valid in the future, and we don't want to
+ // disconnect a peer merely for serving us one too-far-ahead
+ // block header, to prevent an attacker from splitting the
+ // network by mining a block right at the 2 hour boundary.
+ //
+ // TODO: update the DoS logic (or, rather, rewrite the
+ // DoS-interface between validation and net_processing) so that
+ // the interface is cleaner, and so that we disconnect on all the
+ // reasons that a peer's headers chain is incompatible
+ // with ours (eg block->nVersion softforks, MTP violations,
+ // etc), and not just the duplicate-invalid case.
+ pfrom->fDisconnect = true;
+ }
return error("invalid header received");
}
}
@@ -2197,7 +2232,6 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
// If we end up treating this as a plain headers message, call that as well
// without cs_main.
bool fRevertToHeaderProcessing = false;
- CDataStream vHeadersMsg(SER_NETWORK, PROTOCOL_VERSION);
// Keep a CBlock for "optimistic" compactblock reconstructions (see
// below)
@@ -2314,10 +2348,6 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
return true;
} else {
// If this was an announce-cmpctblock, we want the same treatment as a header message
- // Dirty hack to process as if it were just a headers message (TODO: move message handling into their own functions)
- std::vector<CBlock> headers;
- headers.push_back(cmpctblock.header);
- vHeadersMsg << headers;
fRevertToHeaderProcessing = true;
}
}
@@ -2326,8 +2356,14 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
if (fProcessBLOCKTXN)
return ProcessMessage(pfrom, NetMsgType::BLOCKTXN, blockTxnMsg, nTimeReceived, chainparams, connman, interruptMsgProc);
- if (fRevertToHeaderProcessing)
- return ProcessMessage(pfrom, NetMsgType::HEADERS, vHeadersMsg, nTimeReceived, chainparams, connman, interruptMsgProc);
+ if (fRevertToHeaderProcessing) {
+ // Headers received from HB compact block peers are permitted to be
+ // relayed before full validation (see BIP 152), so we don't want to disconnect
+ // the peer if the header turns out to be for an invalid block.
+ // Note that if a peer tries to build on an invalid chain, that
+ // will be detected and the peer will be banned.
+ return ProcessHeadersMessage(pfrom, connman, {cmpctblock.header}, chainparams, /*punish_duplicate_invalid=*/false);
+ }
if (fBlockReconstructed) {
// If we got here, we were able to optimistically reconstruct a
@@ -2458,7 +2494,12 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
ReadCompactSize(vRecv); // ignore tx count; assume it is 0.
}
- return ProcessHeadersMessage(pfrom, connman, headers, chainparams);
+ // Headers received via a HEADERS message should be valid, and reflect
+ // the chain the peer is on. If we receive a known-invalid header,
+ // disconnect the peer if it is using one of our outbound connection
+ // slots.
+ bool should_punish = !pfrom->fInbound && !pfrom->m_manual_connection;
+ return ProcessHeadersMessage(pfrom, connman, headers, chainparams, should_punish);
}
else if (strCommand == NetMsgType::BLOCK && !fImporting && !fReindex) // Ignore blocks received while importing
diff --git a/src/validation.cpp b/src/validation.cpp
index 3bff2d8..c52f8bf 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3064,13 +3064,15 @@ static bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state
}
// Exposed wrapper for AcceptBlockHeader
-bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex)
+bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex, CBlockHeader *first_invalid)
{
+ if (first_invalid != nullptr) first_invalid->SetNull();
{
LOCK(cs_main);
for (const CBlockHeader& header : headers) {
CBlockIndex *pindex = nullptr; // Use a temp pindex instead of ppindex to avoid a const_cast
if (!AcceptBlockHeader(header, state, chainparams, &pindex)) {
+ if (first_invalid) *first_invalid = header;
return false;
}
if (ppindex) {
diff --git a/src/validation.h b/src/validation.h
index f3d88d3..4acdac8 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -248,8 +248,9 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
* @param[out] state This may be set to an Error state if any error occurred processing them
* @param[in] chainparams The params for the chain we want to connect to
* @param[out] ppindex If set, the pointer will be set to point to the last new block index object for the given headers
+ * @param[out] first_invalid First header that fails validation, if one exists
*/
-bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& block, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex=nullptr);
+bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& block, CValidationState& state, const CChainParams& chainparams, const CBlockIndex** ppindex=nullptr, CBlockHeader *first_invalid=nullptr);
/** Check whether enough disk space is available for an incoming block */
bool CheckDiskSpace(uint64_t nAdditionalBytes = 0);
--
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