From c45b9fb54c5ca068a5e276c3bd6ebf4ae720f6f7 Mon Sep 17 00:00:00 2001 From: Cory Fields Date: Tue, 7 Feb 2017 12:02:02 -0500 Subject: [PATCH 1/6] net: correctly ban before the handshake is complete 7a8c251901 made a change to avoid getting into SendMessages() until the version handshake (VERSION + VERACK) is complete. That was done to avoid leaking out messages to nodes who could connect, but never bothered sending us their version/verack. Unfortunately, the ban tally and possible disconnect are done as part of SendMessages(). So after 7a8c251901, if a peer managed to do something bannable before completing the handshake (say send 100 non-version messages before their version), they wouldn't actually end up getting disconnected/banned. That's fixed here by checking the banscore as part of ProcessMessages() in addition to SendMessages(). --- src/net_processing.cpp | 60 ++++++++++++++++++++++++++---------------- 1 file changed, 37 insertions(+), 23 deletions(-) diff --git a/src/net_processing.cpp b/src/net_processing.cpp index bb14e69d83c..587e857970c 100644 --- a/src/net_processing.cpp +++ b/src/net_processing.cpp @@ -2596,6 +2596,36 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr return true; } +static bool SendRejectsAndCheckIfBanned(CNode* pnode, CConnman& connman) +{ + AssertLockHeld(cs_main); + CNodeState &state = *State(pnode->GetId()); + + BOOST_FOREACH(const CBlockReject& reject, state.rejects) { + connman.PushMessage(pnode, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, (std::string)NetMsgType::BLOCK, reject.chRejectCode, reject.strRejectReason, reject.hashBlock)); + } + state.rejects.clear(); + + if (state.fShouldBan) { + state.fShouldBan = false; + if (pnode->fWhitelisted) + LogPrintf("Warning: not punishing whitelisted peer %s!\n", pnode->addr.ToString()); + else if (pnode->fAddnode) + LogPrintf("Warning: not punishing addnoded peer %s!\n", pnode->addr.ToString()); + else { + pnode->fDisconnect = true; + if (pnode->addr.IsLocal()) + LogPrintf("Warning: not banning local peer %s!\n", pnode->addr.ToString()); + else + { + connman.Ban(pnode->addr, BanReasonNodeMisbehaving); + } + } + return true; + } + return false; +} + bool ProcessMessages(CNode* pfrom, CConnman& connman, const std::atomic& interruptMsgProc) { const CChainParams& chainparams = Params(); @@ -2706,8 +2736,12 @@ bool ProcessMessages(CNode* pfrom, CConnman& connman, const std::atomic& i PrintExceptionContinue(NULL, "ProcessMessages()"); } - if (!fRet) + if (!fRet) { LogPrintf("%s(%s, %u bytes) FAILED peer=%d\n", __func__, SanitizeString(strCommand), nMessageSize, pfrom->id); + } + + LOCK(cs_main); + SendRejectsAndCheckIfBanned(pfrom, connman); return fMoreWork; } @@ -2773,30 +2807,10 @@ bool SendMessages(CNode* pto, CConnman& connman, const std::atomic& interr if (!lockMain) return true; + if (SendRejectsAndCheckIfBanned(pto, connman)) + return true; CNodeState &state = *State(pto->GetId()); - BOOST_FOREACH(const CBlockReject& reject, state.rejects) - connman.PushMessage(pto, msgMaker.Make(NetMsgType::REJECT, (std::string)NetMsgType::BLOCK, reject.chRejectCode, reject.strRejectReason, reject.hashBlock)); - state.rejects.clear(); - - if (state.fShouldBan) { - state.fShouldBan = false; - if (pto->fWhitelisted) - LogPrintf("Warning: not punishing whitelisted peer %s!\n", pto->addr.ToString()); - else if (pto->fAddnode) - LogPrintf("Warning: not punishing addnoded peer %s!\n", pto->addr.ToString()); - else { - pto->fDisconnect = true; - if (pto->addr.IsLocal()) - LogPrintf("Warning: not banning local peer %s!\n", pto->addr.ToString()); - else - { - connman.Ban(pto->addr, BanReasonNodeMisbehaving); - } - return true; - } - } - // Address refresh broadcast int64_t nNow = GetTimeMicros(); if (!IsInitialBlockDownload() && pto->nNextLocalAddrSend < nNow) { From 8502e7acbe0f42fd6e6979681bc9c4610c4fb8cb Mon Sep 17 00:00:00 2001 From: Cory Fields Date: Wed, 8 Feb 2017 01:02:49 -0500 Subject: [PATCH 2/6] net: parse reject earlier Prior to this change, all messages were ignored until a VERSION message was received, as well as possibly incurring a ban score. Since REJECT messages can be sent at any time (including as a response to a bad VERSION message), make sure to always parse them. Moving this parsing up keeps it from being caught in the if (pfrom->nVersion == 0) check below. --- src/net_processing.cpp | 50 ++++++++++++++++++++---------------------- 1 file changed, 24 insertions(+), 26 deletions(-) diff --git a/src/net_processing.cpp b/src/net_processing.cpp index 587e857970c..b304da76c25 100644 --- a/src/net_processing.cpp +++ b/src/net_processing.cpp @@ -1190,8 +1190,31 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr } } + if (strCommand == NetMsgType::REJECT) + { + if (fDebug) { + try { + std::string strMsg; unsigned char ccode; std::string strReason; + vRecv >> LIMITED_STRING(strMsg, CMessageHeader::COMMAND_SIZE) >> ccode >> LIMITED_STRING(strReason, MAX_REJECT_MESSAGE_LENGTH); + + std::ostringstream ss; + ss << strMsg << " code " << itostr(ccode) << ": " << strReason; - if (strCommand == NetMsgType::VERSION) + if (strMsg == NetMsgType::BLOCK || strMsg == NetMsgType::TX) + { + uint256 hash; + vRecv >> hash; + ss << ": hash " << hash.ToString(); + } + LogPrint("net", "Reject %s\n", SanitizeString(ss.str())); + } catch (const std::ios_base::failure&) { + // Avoid feedback loops by preventing reject messages from triggering a new reject message. + LogPrint("net", "Unparseable reject message received\n"); + } + } + } + + else if (strCommand == NetMsgType::VERSION) { // Each connection can only send one version message if (pfrom->nVersion != 0) @@ -2544,31 +2567,6 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr pfrom->fRelayTxes = true; } - - else if (strCommand == NetMsgType::REJECT) - { - if (fDebug) { - try { - std::string strMsg; unsigned char ccode; std::string strReason; - vRecv >> LIMITED_STRING(strMsg, CMessageHeader::COMMAND_SIZE) >> ccode >> LIMITED_STRING(strReason, MAX_REJECT_MESSAGE_LENGTH); - - std::ostringstream ss; - ss << strMsg << " code " << itostr(ccode) << ": " << strReason; - - if (strMsg == NetMsgType::BLOCK || strMsg == NetMsgType::TX) - { - uint256 hash; - vRecv >> hash; - ss << ": hash " << hash.ToString(); - } - LogPrint("net", "Reject %s\n", SanitizeString(ss.str())); - } catch (const std::ios_base::failure&) { - // Avoid feedback loops by preventing reject messages from triggering a new reject message. - LogPrint("net", "Unparseable reject message received\n"); - } - } - } - else if (strCommand == NetMsgType::FEEFILTER) { CAmount newFeeFilter = 0; vRecv >> newFeeFilter; From cbfc5a6728d389fbb15e0555cdf50f1b04595106 Mon Sep 17 00:00:00 2001 From: Cory Fields Date: Wed, 8 Feb 2017 01:04:53 -0500 Subject: [PATCH 3/6] net: require a verack before responding to anything else 7a8c251901 made this logic hard to follow. After that change, messages would not be sent to a peer via SendMessages() before the handshake was complete, but messages could still be sent as a response to an incoming message. For example, if a peer had not yet sent a verack, we wouldn't notify it about new blocks, but we would respond to a PING with a PONG. This change makes the behavior straightforward: until we've received a verack, never send any message other than version/verack/reject. The behavior until a VERACK is received has always been undefined, this change just tightens our policy. This also makes testing much easier, because we can now connect but not send version/verack, and anything sent to us is an error. --- src/net_processing.cpp | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/net_processing.cpp b/src/net_processing.cpp index b304da76c25..f458a352560 100644 --- a/src/net_processing.cpp +++ b/src/net_processing.cpp @@ -1420,6 +1420,13 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr pfrom->fSuccessfullyConnected = true; } + else if (!pfrom->fSuccessfullyConnected) + { + // Must have a verack message before anything else + LOCK(cs_main); + Misbehaving(pfrom->GetId(), 1); + return false; + } else if (strCommand == NetMsgType::ADDR) { From 5b5e4f8330634dc33446854677badc52aef43b82 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Tue, 7 Feb 2017 17:35:57 -0500 Subject: [PATCH 4/6] qa: mininode learns when a socket connects, not its first action --- qa/rpc-tests/test_framework/mininode.py | 36 ++++++++++++++++--------- 1 file changed, 24 insertions(+), 12 deletions(-) diff --git a/qa/rpc-tests/test_framework/mininode.py b/qa/rpc-tests/test_framework/mininode.py index 91daa4ab1f5..696a065282c 100755 --- a/qa/rpc-tests/test_framework/mininode.py +++ b/qa/rpc-tests/test_framework/mininode.py @@ -1614,7 +1614,7 @@ class NodeConn(asyncore.dispatcher): "regtest": b"\xfa\xbf\xb5\xda", # regtest } - def __init__(self, dstaddr, dstport, rpc, callback, net="regtest", services=NODE_NETWORK): + def __init__(self, dstaddr, dstport, rpc, callback, net="regtest", services=NODE_NETWORK, send_version=True): asyncore.dispatcher.__init__(self, map=mininode_socket_map) self.log = logging.getLogger("NodeConn(%s:%d)" % (dstaddr, dstport)) self.dstaddr = dstaddr @@ -1631,14 +1631,16 @@ class NodeConn(asyncore.dispatcher): self.disconnect = False self.nServices = 0 - # stuff version msg into sendbuf - vt = msg_version() - vt.nServices = services - vt.addrTo.ip = self.dstaddr - vt.addrTo.port = self.dstport - vt.addrFrom.ip = "0.0.0.0" - vt.addrFrom.port = 0 - self.send_message(vt, True) + if send_version: + # stuff version msg into sendbuf + vt = msg_version() + vt.nServices = services + vt.addrTo.ip = self.dstaddr + vt.addrTo.port = self.dstport + vt.addrFrom.ip = "0.0.0.0" + vt.addrFrom.port = 0 + self.send_message(vt, True) + print('MiniNode: Connecting to Bitcoin Node IP # ' + dstaddr + ':' \ + str(dstport)) @@ -1652,8 +1654,9 @@ class NodeConn(asyncore.dispatcher): self.log.debug(msg) def handle_connect(self): - self.show_debug_msg("MiniNode: Connected & Listening: \n") - self.state = "connected" + if self.state != "connected": + self.show_debug_msg("MiniNode: Connected & Listening: \n") + self.state = "connected" def handle_close(self): self.show_debug_msg("MiniNode: Closing Connection to %s:%d... " @@ -1681,11 +1684,20 @@ class NodeConn(asyncore.dispatcher): def writable(self): with mininode_lock: + pre_connection = self.state == "connecting" length = len(self.sendbuf) - return (length > 0) + return (length > 0 or pre_connection) def handle_write(self): with mininode_lock: + # asyncore does not expose socket connection, only the first read/write + # event, thus we must check connection manually here to know when we + # actually connect + if self.state == "connecting": + self.handle_connect() + if not self.writable(): + return + try: sent = self.send(self.sendbuf) except: From 8650bbb660eaf8c81d714f1518ecc8c35ae17463 Mon Sep 17 00:00:00 2001 From: Matt Corallo Date: Tue, 7 Feb 2017 17:40:28 -0500 Subject: [PATCH 5/6] qa: Expose on-connection to mininode listeners --- qa/rpc-tests/test_framework/mininode.py | 2 ++ 1 file changed, 2 insertions(+) diff --git a/qa/rpc-tests/test_framework/mininode.py b/qa/rpc-tests/test_framework/mininode.py index 696a065282c..5b563c58ae1 100755 --- a/qa/rpc-tests/test_framework/mininode.py +++ b/qa/rpc-tests/test_framework/mininode.py @@ -1540,6 +1540,7 @@ class NodeConnCB(object): if conn.ver_send > BIP0031_VERSION: conn.send_message(msg_pong(message.nonce)) def on_reject(self, conn, message): pass + def on_open(self, conn): pass def on_close(self, conn): pass def on_mempool(self, conn): pass def on_pong(self, conn, message): pass @@ -1657,6 +1658,7 @@ class NodeConn(asyncore.dispatcher): if self.state != "connected": self.show_debug_msg("MiniNode: Connected & Listening: \n") self.state = "connected" + self.cb.on_open(self) def handle_close(self): self.show_debug_msg("MiniNode: Closing Connection to %s:%d... " From d9434918d277bba534933ebc8c63ba81e613f603 Mon Sep 17 00:00:00 2001 From: Cory Fields Date: Wed, 8 Feb 2017 01:17:58 -0500 Subject: [PATCH 6/6] qa: add a test to detect leaky p2p messages This is certainly not exhaustive, but it's better than nothing. Adds checks for: - Any message received before sending a version - Any message received other than version/reject before sending a verack It also tries to goad the remote into sending a pong, address, or block announcement. --- qa/pull-tester/rpc-tests.py | 1 + qa/rpc-tests/p2p-leaktests.py | 145 ++++++++++++++++++++++++++++++++++ 2 files changed, 146 insertions(+) create mode 100755 qa/rpc-tests/p2p-leaktests.py diff --git a/qa/pull-tester/rpc-tests.py b/qa/pull-tester/rpc-tests.py index 26bc6a73dfa..31018125416 100755 --- a/qa/pull-tester/rpc-tests.py +++ b/qa/pull-tester/rpc-tests.py @@ -154,6 +154,7 @@ testScripts = [ 'bumpfee.py', 'rpcnamedargs.py', 'listsinceblock.py', + 'p2p-leaktests.py', ] if ENABLE_ZMQ: testScripts.append('zmq_test.py') diff --git a/qa/rpc-tests/p2p-leaktests.py b/qa/rpc-tests/p2p-leaktests.py new file mode 100755 index 00000000000..41ca84d7798 --- /dev/null +++ b/qa/rpc-tests/p2p-leaktests.py @@ -0,0 +1,145 @@ +#!/usr/bin/env python3 +# Copyright (c) 2017 The Bitcoin Core developers +# Distributed under the MIT software license, see the accompanying +# file COPYING or http://www.opensource.org/licenses/mit-license.php. + +from test_framework.mininode import * +from test_framework.test_framework import BitcoinTestFramework +from test_framework.util import * + +''' +Test for message sending before handshake completion + +A node should never send anything other than VERSION/VERACK/REJECT until it's +received a VERACK. + +This test connects to a node and sends it a few messages, trying to intice it +into sending us something it shouldn't. +''' + +banscore = 10 + +class CLazyNode(NodeConnCB): + def __init__(self): + self.connection = None + self.unexpected_msg = False + self.connected = False + super().__init__() + + def add_connection(self, conn): + self.connection = conn + + def send_message(self, message): + self.connection.send_message(message) + + def bad_message(self, message): + self.unexpected_msg = True + print("should not have received message: %s" % message.command) + + def on_open(self, conn): + self.connected = True + + def on_version(self, conn, message): self.bad_message(message) + def on_verack(self, conn, message): self.bad_message(message) + def on_reject(self, conn, message): self.bad_message(message) + def on_inv(self, conn, message): self.bad_message(message) + def on_addr(self, conn, message): self.bad_message(message) + def on_alert(self, conn, message): self.bad_message(message) + def on_getdata(self, conn, message): self.bad_message(message) + def on_getblocks(self, conn, message): self.bad_message(message) + def on_tx(self, conn, message): self.bad_message(message) + def on_block(self, conn, message): self.bad_message(message) + def on_getaddr(self, conn, message): self.bad_message(message) + def on_headers(self, conn, message): self.bad_message(message) + def on_getheaders(self, conn, message): self.bad_message(message) + def on_ping(self, conn, message): self.bad_message(message) + def on_mempool(self, conn): self.bad_message(message) + def on_pong(self, conn, message): self.bad_message(message) + def on_feefilter(self, conn, message): self.bad_message(message) + def on_sendheaders(self, conn, message): self.bad_message(message) + def on_sendcmpct(self, conn, message): self.bad_message(message) + def on_cmpctblock(self, conn, message): self.bad_message(message) + def on_getblocktxn(self, conn, message): self.bad_message(message) + def on_blocktxn(self, conn, message): self.bad_message(message) + +# Node that never sends a version. We'll use this to send a bunch of messages +# anyway, and eventually get disconnected. +class CNodeNoVersionBan(CLazyNode): + def __init__(self): + super().__init__() + + # send a bunch of veracks without sending a message. This should get us disconnected. + # NOTE: implementation-specific check here. Remove if bitcoind ban behavior changes + def on_open(self, conn): + super().on_open(conn) + for i in range(banscore): + self.send_message(msg_verack()) + + def on_reject(self, conn, message): pass + +# Node that never sends a version. This one just sits idle and hopes to receive +# any message (it shouldn't!) +class CNodeNoVersionIdle(CLazyNode): + def __init__(self): + super().__init__() + +# Node that sends a version but not a verack. +class CNodeNoVerackIdle(CLazyNode): + def __init__(self): + self.version_received = False + super().__init__() + + def on_reject(self, conn, message): pass + def on_verack(self, conn, message): pass + # When version is received, don't reply with a verack. Instead, see if the + # node will give us a message that it shouldn't. This is not an exhaustive + # list! + def on_version(self, conn, message): + self.version_received = True + conn.send_message(msg_ping()) + conn.send_message(msg_getaddr()) + +class P2PLeakTest(BitcoinTestFramework): + def __init__(self): + super().__init__() + self.num_nodes = 1 + def setup_network(self): + extra_args = [['-debug', '-banscore='+str(banscore)] + for i in range(self.num_nodes)] + self.nodes = start_nodes(self.num_nodes, self.options.tmpdir, extra_args) + + def run_test(self): + no_version_bannode = CNodeNoVersionBan() + no_version_idlenode = CNodeNoVersionIdle() + no_verack_idlenode = CNodeNoVerackIdle() + + connections = [] + connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], no_version_bannode, send_version=False)) + connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], no_version_idlenode, send_version=False)) + connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], no_verack_idlenode)) + no_version_bannode.add_connection(connections[0]) + no_version_idlenode.add_connection(connections[1]) + no_verack_idlenode.add_connection(connections[2]) + + NetworkThread().start() # Start up network handling in another thread + + assert(wait_until(lambda: no_version_bannode.connected and no_version_idlenode.connected and no_verack_idlenode.version_received, timeout=10)) + + # Mine a block and make sure that it's not sent to the connected nodes + self.nodes[0].generate(1) + + #Give the node enough time to possibly leak out a message + time.sleep(5) + + #This node should have been banned + assert(no_version_bannode.connection.state == "closed") + + [conn.disconnect_node() for conn in connections] + + # Make sure no unexpected messages came in + assert(no_version_bannode.unexpected_msg == False) + assert(no_version_idlenode.unexpected_msg == False) + assert(no_verack_idlenode.unexpected_msg == False) + +if __name__ == '__main__': + P2PLeakTest().main()