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-rw-r--r--src/main.cpp43
-rw-r--r--src/main.h2
-rw-r--r--src/test/script_P2SH_tests.cpp118
3 files changed, 97 insertions, 66 deletions
diff --git a/src/main.cpp b/src/main.cpp
index d3f04b95fa..ecabd9ec2c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -582,15 +582,13 @@ bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime)
}
//
-// Check transaction inputs, and make sure any
-// pay-to-script-hash transactions are evaluating IsStandard scripts
+// Check transaction inputs to mitigate two
+// potential denial-of-service attacks:
//
-// Why bother? To avoid denial-of-service attacks; an attacker
-// can submit a standard HASH... OP_EQUAL transaction,
-// which will get accepted into blocks. The redemption
-// script can be anything; an attacker could use a very
-// expensive-to-check-upon-redemption script like:
-// DUP CHECKSIG DROP ... repeated 100 times... OP_1
+// 1. scriptSigs with extra data stuffed into them,
+// not consumed by scriptPubKey (or P2SH script)
+// 2. P2SH scripts with a crazy number of expensive
+// CHECKSIG/CHECKMULTISIG operations
//
bool AreInputsStandard(const CTransaction& tx, CCoinsViewCache& mapInputs)
{
@@ -614,8 +612,9 @@ bool AreInputsStandard(const CTransaction& tx, CCoinsViewCache& mapInputs)
// Transactions with extra stuff in their scriptSigs are
// non-standard. Note that this EvalScript() call will
// be quick, because if there are any operations
- // beside "push data" in the scriptSig the
- // IsStandard() call returns false
+ // beside "push data" in the scriptSig
+ // IsStandard() will have already returned false
+ // and this method isn't called.
vector<vector<unsigned char> > stack;
if (!EvalScript(stack, tx.vin[i].scriptSig, tx, i, false, 0))
return false;
@@ -627,16 +626,20 @@ bool AreInputsStandard(const CTransaction& tx, CCoinsViewCache& mapInputs)
CScript subscript(stack.back().begin(), stack.back().end());
vector<vector<unsigned char> > vSolutions2;
txnouttype whichType2;
- if (!Solver(subscript, whichType2, vSolutions2))
- return false;
- if (whichType2 == TX_SCRIPTHASH)
- return false;
-
- int tmpExpected;
- tmpExpected = ScriptSigArgsExpected(whichType2, vSolutions2);
- if (tmpExpected < 0)
- return false;
- nArgsExpected += tmpExpected;
+ if (Solver(subscript, whichType2, vSolutions2))
+ {
+ int tmpExpected = ScriptSigArgsExpected(whichType2, vSolutions2);
+ if (tmpExpected < 0)
+ return false;
+ nArgsExpected += tmpExpected;
+ }
+ else
+ {
+ // Any other Script with less than 15 sigops OK:
+ unsigned int sigops = subscript.GetSigOpCount(true);
+ // ... extra data left on the stack after execution is OK, too:
+ return (sigops <= MAX_P2SH_SIGOPS);
+ }
}
if (stack.size() != (unsigned int)nArgsExpected)
diff --git a/src/main.h b/src/main.h
index 27041a0026..ff1f742d1e 100644
--- a/src/main.h
+++ b/src/main.h
@@ -43,6 +43,8 @@ static const unsigned int DEFAULT_BLOCK_PRIORITY_SIZE = 50000;
static const unsigned int MAX_STANDARD_TX_SIZE = 100000;
/** The maximum allowed number of signature check operations in a block (network rule) */
static const unsigned int MAX_BLOCK_SIGOPS = MAX_BLOCK_SIZE/50;
+/** Maxiumum number of signature check operations in an IsStandard() P2SH script */
+static const unsigned int MAX_P2SH_SIGOPS = 15;
/** The maximum number of orphan transactions kept in memory */
static const unsigned int MAX_ORPHAN_TRANSACTIONS = MAX_BLOCK_SIZE/100;
/** Default for -maxorphanblocks, maximum number of orphan blocks kept in memory */
diff --git a/src/test/script_P2SH_tests.cpp b/src/test/script_P2SH_tests.cpp
index a75593a8b2..6ae2b9cf64 100644
--- a/src/test/script_P2SH_tests.cpp
+++ b/src/test/script_P2SH_tests.cpp
@@ -256,46 +256,61 @@ BOOST_AUTO_TEST_CASE(AreInputsStandard)
CCoinsView coinsDummy;
CCoinsViewCache coins(coinsDummy);
CBasicKeyStore keystore;
- CKey key[3];
+ CKey key[6];
vector<CPubKey> keys;
- for (int i = 0; i < 3; i++)
+ for (int i = 0; i < 6; i++)
{
key[i].MakeNewKey(true);
keystore.AddKey(key[i]);
- keys.push_back(key[i].GetPubKey());
}
+ for (int i = 0; i < 3; i++)
+ keys.push_back(key[i].GetPubKey());
CMutableTransaction txFrom;
- txFrom.vout.resize(6);
+ txFrom.vout.resize(7);
// First three are standard:
CScript pay1; pay1.SetDestination(key[0].GetPubKey().GetID());
keystore.AddCScript(pay1);
- CScript payScriptHash1; payScriptHash1.SetDestination(pay1.GetID());
CScript pay1of3; pay1of3.SetMultisig(1, keys);
- txFrom.vout[0].scriptPubKey = payScriptHash1;
+ txFrom.vout[0].scriptPubKey.SetDestination(pay1.GetID()); // P2SH (OP_CHECKSIG)
txFrom.vout[0].nValue = 1000;
- txFrom.vout[1].scriptPubKey = pay1;
+ txFrom.vout[1].scriptPubKey = pay1; // ordinary OP_CHECKSIG
txFrom.vout[1].nValue = 2000;
- txFrom.vout[2].scriptPubKey = pay1of3;
+ txFrom.vout[2].scriptPubKey = pay1of3; // ordinary OP_CHECKMULTISIG
txFrom.vout[2].nValue = 3000;
- // Last three non-standard:
- CScript empty;
- keystore.AddCScript(empty);
- txFrom.vout[3].scriptPubKey = empty;
+ // vout[3] is complicated 1-of-3 AND 2-of-3
+ // ... that is OK if wrapped in P2SH:
+ CScript oneAndTwo;
+ oneAndTwo << OP_1 << key[0].GetPubKey() << key[1].GetPubKey() << key[2].GetPubKey();
+ oneAndTwo << OP_3 << OP_CHECKMULTISIGVERIFY;
+ oneAndTwo << OP_2 << key[3].GetPubKey() << key[4].GetPubKey() << key[5].GetPubKey();
+ oneAndTwo << OP_3 << OP_CHECKMULTISIG;
+ keystore.AddCScript(oneAndTwo);
+ txFrom.vout[3].scriptPubKey.SetDestination(oneAndTwo.GetID());
txFrom.vout[3].nValue = 4000;
- // Can't use SetPayToScriptHash, it checks for the empty Script. So:
- txFrom.vout[4].scriptPubKey << OP_HASH160 << Hash160(empty) << OP_EQUAL;
+
+ // vout[4] is max sigops:
+ CScript fifteenSigops; fifteenSigops << OP_1;
+ for (int i = 0; i < MAX_P2SH_SIGOPS; i++)
+ fifteenSigops << key[i%3].GetPubKey();
+ fifteenSigops << OP_15 << OP_CHECKMULTISIG;
+ keystore.AddCScript(fifteenSigops);
+ txFrom.vout[4].scriptPubKey.SetDestination(fifteenSigops.GetID());
txFrom.vout[4].nValue = 5000;
- CScript oneOfEleven;
- oneOfEleven << OP_1;
- for (int i = 0; i < 11; i++)
- oneOfEleven << key[0].GetPubKey();
- oneOfEleven << OP_11 << OP_CHECKMULTISIG;
- txFrom.vout[5].scriptPubKey.SetDestination(oneOfEleven.GetID());
- txFrom.vout[5].nValue = 6000;
+
+ // vout[5/6] are non-standard because they exceed MAX_P2SH_SIGOPS
+ CScript sixteenSigops; sixteenSigops << OP_16 << OP_CHECKMULTISIG;
+ keystore.AddCScript(sixteenSigops);
+ txFrom.vout[5].scriptPubKey.SetDestination(fifteenSigops.GetID());
+ txFrom.vout[5].nValue = 5000;
+ CScript twentySigops; twentySigops << OP_CHECKMULTISIG;
+ keystore.AddCScript(twentySigops);
+ txFrom.vout[6].scriptPubKey.SetDestination(twentySigops.GetID());
+ txFrom.vout[6].nValue = 6000;
+
coins.SetCoins(txFrom.GetHash(), CCoins(txFrom, 0));
@@ -303,19 +318,24 @@ BOOST_AUTO_TEST_CASE(AreInputsStandard)
txTo.vout.resize(1);
txTo.vout[0].scriptPubKey.SetDestination(key[1].GetPubKey().GetID());
- txTo.vin.resize(3);
- txTo.vin[0].prevout.n = 0;
- txTo.vin[0].prevout.hash = txFrom.GetHash();
+ txTo.vin.resize(5);
+ for (int i = 0; i < 5; i++)
+ {
+ txTo.vin[i].prevout.n = i;
+ txTo.vin[i].prevout.hash = txFrom.GetHash();
+ }
BOOST_CHECK(SignSignature(keystore, txFrom, txTo, 0));
- txTo.vin[1].prevout.n = 1;
- txTo.vin[1].prevout.hash = txFrom.GetHash();
BOOST_CHECK(SignSignature(keystore, txFrom, txTo, 1));
- txTo.vin[2].prevout.n = 2;
- txTo.vin[2].prevout.hash = txFrom.GetHash();
BOOST_CHECK(SignSignature(keystore, txFrom, txTo, 2));
+ // SignSignature doesn't know how to sign these. We're
+ // not testing validating signatures, so just create
+ // dummy signatures that DO include the correct P2SH scripts:
+ txTo.vin[3].scriptSig << OP_11 << OP_11 << static_cast<vector<unsigned char> >(oneAndTwo);
+ txTo.vin[4].scriptSig << static_cast<vector<unsigned char> >(fifteenSigops);
BOOST_CHECK(::AreInputsStandard(txTo, coins));
- BOOST_CHECK_EQUAL(GetP2SHSigOpCount(txTo, coins), 1U);
+ // 22 P2SH sigops for all inputs (1 for vin[0], 6 for vin[3], 15 for vin[4]
+ BOOST_CHECK_EQUAL(GetP2SHSigOpCount(txTo, coins), 22U);
// Make sure adding crap to the scriptSigs makes them non-standard:
for (int i = 0; i < 3; i++)
@@ -326,23 +346,29 @@ BOOST_AUTO_TEST_CASE(AreInputsStandard)
txTo.vin[i].scriptSig = t;
}
- CMutableTransaction txToNonStd;
- txToNonStd.vout.resize(1);
- txToNonStd.vout[0].scriptPubKey.SetDestination(key[1].GetPubKey().GetID());
- txToNonStd.vout[0].nValue = 1000;
- txToNonStd.vin.resize(2);
- txToNonStd.vin[0].prevout.n = 4;
- txToNonStd.vin[0].prevout.hash = txFrom.GetHash();
- txToNonStd.vin[0].scriptSig << Serialize(empty);
- txToNonStd.vin[1].prevout.n = 5;
- txToNonStd.vin[1].prevout.hash = txFrom.GetHash();
- txToNonStd.vin[1].scriptSig << OP_0 << Serialize(oneOfEleven);
-
- BOOST_CHECK(!::AreInputsStandard(txToNonStd, coins));
- BOOST_CHECK_EQUAL(GetP2SHSigOpCount(txToNonStd, coins), 11U);
-
- txToNonStd.vin[0].scriptSig.clear();
- BOOST_CHECK(!::AreInputsStandard(txToNonStd, coins));
+ CMutableTransaction txToNonStd1;
+ txToNonStd1.vout.resize(1);
+ txToNonStd1.vout[0].scriptPubKey.SetDestination(key[1].GetPubKey().GetID());
+ txToNonStd1.vout[0].nValue = 1000;
+ txToNonStd1.vin.resize(1);
+ txToNonStd1.vin[0].prevout.n = 5;
+ txToNonStd1.vin[0].prevout.hash = txFrom.GetHash();
+ txToNonStd1.vin[0].scriptSig << static_cast<vector<unsigned char> >(sixteenSigops);
+
+ BOOST_CHECK(!::AreInputsStandard(txToNonStd1, coins));
+ BOOST_CHECK_EQUAL(GetP2SHSigOpCount(txToNonStd1, coins), 16U);
+
+ CMutableTransaction txToNonStd2;
+ txToNonStd2.vout.resize(1);
+ txToNonStd2.vout[0].scriptPubKey.SetDestination(key[1].GetPubKey().GetID());
+ txToNonStd2.vout[0].nValue = 1000;
+ txToNonStd2.vin.resize(1);
+ txToNonStd2.vin[0].prevout.n = 6;
+ txToNonStd2.vin[0].prevout.hash = txFrom.GetHash();
+ txToNonStd2.vin[0].scriptSig << static_cast<vector<unsigned char> >(twentySigops);
+
+ BOOST_CHECK(!::AreInputsStandard(txToNonStd2, coins));
+ BOOST_CHECK_EQUAL(GetP2SHSigOpCount(txToNonStd2, coins), 20U);
}
BOOST_AUTO_TEST_SUITE_END()
generated by cgit v1.2.3 (git 2.26.2) at 2024-11-15 08:20:24 +0000