Merge #11423: [Policy] Several transaction standardness rules

364bae5 qa: Pad scriptPubKeys to get minimum sized txs (MarcoFalke)
7485488 Policy to reject extremely small transactions (Johnson Lau)
0f8719b Add transaction tests for constant scriptCode (Johnson Lau)
9dabfe4 Add constant scriptCode policy in non-segwit scripts (Johnson Lau)

Pull request description:

  This disables `OP_CODESEPARATOR` in non-segwit scripts (even in an unexecuted branch), and makes a positive `FindAndDelete` result invalid. This ensures that the `scriptCode` serialized in `SignatureHash` is always the same as the script passing to the `EvalScript`.

Tree-SHA512: a0552cb920294d130251c48053fa2ff1fbdd26332e62b52147d918837852750f0ce35ce2cd1cbdb86588943312f8154ccb4925e850dbb7c2254bc353070cd5f8

Author: laanwj

src/policy/policy.h

@@ -22,6 +22,8 @@ static const unsigned int DEFAULT_BLOCK_MAX_WEIGHT = MAX_BLOCK_WEIGHT - 4000;
 static const unsigned int DEFAULT_BLOCK_MIN_TX_FEE = 1000;
 /** The maximum weight for transactions we're willing to relay/mine */
 static const unsigned int MAX_STANDARD_TX_WEIGHT = 400000;
+/** The minimum non-witness size for transactions we're willing to relay/mine (1 segwit input + 1 P2WPKH output = 82 bytes) */
+static const unsigned int MIN_STANDARD_TX_NONWITNESS_SIZE = 82;
 /** Maximum number of signature check operations in an IsStandard() P2SH script */
 static const unsigned int MAX_P2SH_SIGOPS = 15;
 /** The maximum number of sigops we're willing to relay/mine in a single tx */
@@ -63,7 +65,8 @@ static constexpr unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VE
                                                              SCRIPT_VERIFY_LOW_S |
                                                              SCRIPT_VERIFY_WITNESS |
                                                              SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM |
-                                                             SCRIPT_VERIFY_WITNESS_PUBKEYTYPE;
+                                                             SCRIPT_VERIFY_WITNESS_PUBKEYTYPE |
+                                                             SCRIPT_VERIFY_CONST_SCRIPTCODE;
 
 /** For convenience, standard but not mandatory verify flags. */
 static constexpr unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS;

src/script/interpreter.cpp

@@ -336,6 +336,10 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                 opcode == OP_RSHIFT)
                 return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE); // Disabled opcodes.
 
+            // With SCRIPT_VERIFY_CONST_SCRIPTCODE, OP_CODESEPARATOR in non-segwit script is rejected even in an unexecuted branch
+            if (opcode == OP_CODESEPARATOR && sigversion == SigVersion::BASE && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
+                return set_error(serror, SCRIPT_ERR_OP_CODESEPARATOR);
+
             if (fExec && 0 <= opcode && opcode <= OP_PUSHDATA4) {
                 if (fRequireMinimal && !CheckMinimalPush(vchPushValue, opcode)) {
                     return set_error(serror, SCRIPT_ERR_MINIMALDATA);
@@ -899,6 +903,9 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
 
                 case OP_CODESEPARATOR:
                 {
+                    // If SCRIPT_VERIFY_CONST_SCRIPTCODE flag is set, use of OP_CODESEPARATOR is rejected in pre-segwit
+                    // script, even in an unexecuted branch (this is checked above the opcode case statement).
+
                     // Hash starts after the code separator
                     pbegincodehash = pc;
                 }
@@ -919,7 +926,9 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
 
                     // Drop the signature in pre-segwit scripts but not segwit scripts
                     if (sigversion == SigVersion::BASE) {
-                        FindAndDelete(scriptCode, CScript(vchSig));
+                        int found = FindAndDelete(scriptCode, CScript(vchSig));
+                        if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
+                            return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
                     }
 
                     if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, sigversion, serror)) {
@@ -983,7 +992,9 @@ bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript&
                     {
                         valtype& vchSig = stacktop(-isig-k);
                         if (sigversion == SigVersion::BASE) {
-                            FindAndDelete(scriptCode, CScript(vchSig));
+                            int found = FindAndDelete(scriptCode, CScript(vchSig));
+                            if (found > 0 && (flags & SCRIPT_VERIFY_CONST_SCRIPTCODE))
+                                return set_error(serror, SCRIPT_ERR_SIG_FINDANDDELETE);
                         }
                     }
 

src/script/interpreter.h

@@ -111,6 +111,10 @@ enum
     // Public keys in segregated witness scripts must be compressed
     //
     SCRIPT_VERIFY_WITNESS_PUBKEYTYPE = (1U << 15),
+
+    // Making OP_CODESEPARATOR and FindAndDelete fail any non-segwit scripts
+    //
+    SCRIPT_VERIFY_CONST_SCRIPTCODE = (1U << 16),
 };
 
 bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);

src/script/script_error.cpp

@@ -89,6 +89,10 @@ const char* ScriptErrorString(const ScriptError serror)
             return "Witness provided for non-witness script";
         case SCRIPT_ERR_WITNESS_PUBKEYTYPE:
             return "Using non-compressed keys in segwit";
+        case SCRIPT_ERR_OP_CODESEPARATOR:
+            return "Using OP_CODESEPARATOR in non-witness script";
+        case SCRIPT_ERR_SIG_FINDANDDELETE:
+            return "Signature is found in scriptCode";
         case SCRIPT_ERR_UNKNOWN_ERROR:
         case SCRIPT_ERR_ERROR_COUNT:
         default: break;

src/script/script_error.h

@@ -64,6 +64,10 @@ typedef enum ScriptError_t
     SCRIPT_ERR_WITNESS_UNEXPECTED,
     SCRIPT_ERR_WITNESS_PUBKEYTYPE,
 
+    /* Constant scriptCode */
+    SCRIPT_ERR_OP_CODESEPARATOR,
+    SCRIPT_ERR_SIG_FINDANDDELETE,
+
     SCRIPT_ERR_ERROR_COUNT
 } ScriptError;
 

src/test/data/tx_invalid.json

@@ -340,5 +340,53 @@
 [[["9628667ad48219a169b41b020800162287d2c0f713c04157e95c484a8dcb7592", 7500, "0x00 0x20 0x9b66c15b4e0b4eb49fa877982cafded24859fe5b0e2dbfbe4f0df1de7743fd52", 200000]],
 "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", "P2SH,WITNESS"],
 
+["SCRIPT_VERIFY_CONST_SCRIPTCODE tests"],
+["All transactions are copied from OP_CODESEPARATOR tests in tx_valid.json"],
+
+[[["bc7fd132fcf817918334822ee6d9bd95c889099c96e07ca2c1eb2cc70db63224", 0, "CODESEPARATOR 0x21 0x038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041 CHECKSIG"]],
+  "01000000012432b60dc72cebc1a27ce0969c0989c895bdd9e62e8234839117f8fc32d17fbc000000004a493046022100a576b52051962c25e642c0fd3d77ee6c92487048e5d90818bcf5b51abaccd7900221008204f8fb121be4ec3b24483b1f92d89b1b0548513a134e345c5442e86e8617a501ffffffff010000000000000000016a00000000", "P2SH,CONST_SCRIPTCODE"],
+[[["83e194f90b6ef21fa2e3a365b63794fb5daa844bdc9b25de30899fcfe7b01047", 0, "CODESEPARATOR CODESEPARATOR 0x21 0x038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041 CHECKSIG"]],
+  "01000000014710b0e7cf9f8930de259bdc4b84aa5dfb9437b665a3e3a21ff26e0bf994e183000000004a493046022100a166121a61b4eeb19d8f922b978ff6ab58ead8a5a5552bf9be73dc9c156873ea02210092ad9bc43ee647da4f6652c320800debcf08ec20a094a0aaf085f63ecb37a17201ffffffff010000000000000000016a00000000", "P2SH,CONST_SCRIPTCODE"],
+
+[[["326882a7f22b5191f1a0cc9962ca4b878cd969cf3b3a70887aece4d801a0ba5e", 0, "0x21 0x038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041 CODESEPARATOR CHECKSIG"]],
+  "01000000015ebaa001d8e4ec7a88703a3bcf69d98c874bca6299cca0f191512bf2a7826832000000004948304502203bf754d1c6732fbf87c5dcd81258aefd30f2060d7bd8ac4a5696f7927091dad1022100f5bcb726c4cf5ed0ed34cc13dadeedf628ae1045b7cb34421bc60b89f4cecae701ffffffff010000000000000000016a00000000", "P2SH,CONST_SCRIPTCODE"],
+
+[[["a955032f4d6b0c9bfe8cad8f00a8933790b9c1dc28c82e0f48e75b35da0e4944", 0, "0x21 0x038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041 CHECKSIGVERIFY CODESEPARATOR 0x21 0x038479a0fa998cd35259a2ef0a7a5c68662c1474f88ccb6d08a7677bbec7f22041 CHECKSIGVERIFY CODESEPARATOR 1"]],
+  "010000000144490eda355be7480f2ec828dcc1b9903793a8008fad8cfe9b0c6b4d2f0355a900000000924830450221009c0a27f886a1d8cb87f6f595fbc3163d28f7a81ec3c4b252ee7f3ac77fd13ffa02203caa8dfa09713c8c4d7ef575c75ed97812072405d932bd11e6a1593a98b679370148304502201e3861ef39a526406bad1e20ecad06be7375ad40ddb582c9be42d26c3a0d7b240221009d0a3985e96522e59635d19cc4448547477396ce0ef17a58e7d74c3ef464292301ffffffff010000000000000000016a00000000", "P2SH,CONST_SCRIPTCODE"],
+
+["CODESEPARATOR in an unexecuted IF block is still invalid"],
+[[["a955032f4d6b0c9bfe8cad8f00a8933790b9c1dc28c82e0f48e75b35da0e4944", 0, "IF CODESEPARATOR ENDIF 0x21 0x0378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71 CHECKSIGVERIFY CODESEPARATOR 1"]],
+  "010000000144490eda355be7480f2ec828dcc1b9903793a8008fad8cfe9b0c6b4d2f0355a9000000004a48304502207a6974a77c591fa13dff60cabbb85a0de9e025c09c65a4b2285e47ce8e22f761022100f0efaac9ff8ac36b10721e0aae1fb975c90500b50c56e8a0cc52b0403f0425dd0100ffffffff010000000000000000016a00000000", "P2SH,CONST_SCRIPTCODE"],
+
+["CODESEPARATOR in an executed IF block is invalid"],
+[[["a955032f4d6b0c9bfe8cad8f00a8933790b9c1dc28c82e0f48e75b35da0e4944", 0, "IF CODESEPARATOR ENDIF 0x21 0x0378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71 CHECKSIGVERIFY CODESEPARATOR 1"]],
+  "010000000144490eda355be7480f2ec828dcc1b9903793a8008fad8cfe9b0c6b4d2f0355a9000000004a483045022100fa4a74ba9fd59c59f46c3960cf90cbe0d2b743c471d24a3d5d6db6002af5eebb02204d70ec490fd0f7055a7c45f86514336e3a7f03503dacecabb247fc23f15c83510151ffffffff010000000000000000016a00000000", "P2SH,CONST_SCRIPTCODE"],
+
+
+["Using CHECKSIG with singatures in scriptSigs will trigger FindAndDelete, which is invalid"],
+[[["ccf7f4053a02e653c36ac75c891b7496d0dc5ce5214f6c913d9cf8f1329ebee0", 0, "DUP HASH160 0x14 0xee5a6aa40facefb2655ac23c0c28c57c65c41f9b EQUALVERIFY CHECKSIG"]],
+  "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", "P2SH,CONST_SCRIPTCODE"],
+
+["OP_CODESEPARATOR in scriptSig is invalid"],
+[[["10c9f0effe83e97f80f067de2b11c6a00c3088a4bce42c5ae761519af9306f3c", 1, "DUP HASH160 0x14 0xee5a6aa40facefb2655ac23c0c28c57c65c41f9b EQUALVERIFY CHECKSIG"]],
+  "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", "P2SH,CONST_SCRIPTCODE"],
+
+["Again, FindAndDelete() in scriptSig"],
+[[["6056ebd549003b10cbbd915cea0d82209fe40b8617104be917a26fa92cbe3d6f", 0, "DUP HASH160 0x14 0xee5a6aa40facefb2655ac23c0c28c57c65c41f9b EQUALVERIFY CHECKSIG"]],
+  "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", "P2SH,CONST_SCRIPTCODE"],
+
+[[["5a6b0021a6042a686b6b94abc36b387bef9109847774e8b1e51eb8cc55c53921", 1, "DUP HASH160 0x14 0xee5a6aa40facefb2655ac23c0c28c57c65c41f9b EQUALVERIFY CHECKSIG"]],
+  "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", "P2SH,CONST_SCRIPTCODE"],
+
+["FindAndDelete() in redeemScript"],
+[[["b5b598de91787439afd5938116654e0b16b7a0d0f82742ba37564219c5afcbf9", 0, "DUP HASH160 0x14 0xf6f365c40f0739b61de827a44751e5e99032ed8f EQUALVERIFY CHECKSIG"],
+  ["ab9805c6d57d7070d9a42c5176e47bb705023e6b67249fb6760880548298e742", 0, "HASH160 0x14 0xd8dacdadb7462ae15cd906f1878706d0da8660e6 EQUAL"]],
+  "0100000002f9cbafc519425637ba4227f8d0a0b7160b4e65168193d5af39747891de98b5b5000000006b4830450221008dd619c563e527c47d9bd53534a770b102e40faa87f61433580e04e271ef2f960220029886434e18122b53d5decd25f1f4acb2480659fea20aabd856987ba3c3907e0121022b78b756e2258af13779c1a1f37ea6800259716ca4b7f0b87610e0bf3ab52a01ffffffff42e7988254800876b69f24676b3e0205b77be476512ca4d970707dd5c60598ab00000000fd260100483045022015bd0139bcccf990a6af6ec5c1c52ed8222e03a0d51c334df139968525d2fcd20221009f9efe325476eb64c3958e4713e9eefe49bf1d820ed58d2112721b134e2a1a53034930460221008431bdfa72bc67f9d41fe72e94c88fb8f359ffa30b33c72c121c5a877d922e1002210089ef5fc22dd8bfc6bf9ffdb01a9862d27687d424d1fefbab9e9c7176844a187a014c9052483045022015bd0139bcccf990a6af6ec5c1c52ed8222e03a0d51c334df139968525d2fcd20221009f9efe325476eb64c3958e4713e9eefe49bf1d820ed58d2112721b134e2a1a5303210378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71210378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c7153aeffffffff01a08601000000000017a914d8dacdadb7462ae15cd906f1878706d0da8660e68700000000", "P2SH,CONST_SCRIPTCODE"],
+
+["FindAndDelete() in bare CHECKMULTISIG"],
+[[["ceafe58e0f6e7d67c0409fbbf673c84c166e3c5d3c24af58f7175b18df3bb3db", 0, "DUP HASH160 0x14 0xf6f365c40f0739b61de827a44751e5e99032ed8f EQUALVERIFY CHECKSIG"],
+  ["ceafe58e0f6e7d67c0409fbbf673c84c166e3c5d3c24af58f7175b18df3bb3db", 1, "2 0x48 0x3045022015bd0139bcccf990a6af6ec5c1c52ed8222e03a0d51c334df139968525d2fcd20221009f9efe325476eb64c3958e4713e9eefe49bf1d820ed58d2112721b134e2a1a5303 0x21 0x0378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71 0x21 0x0378d430274f8c5ec1321338151e9f27f4c676a008bdf8638d07c0b6be9ab35c71 3 CHECKMULTISIG"]],
+  "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", "P2SH,CONST_SCRIPTCODE"],
+
 ["Make diffs cleaner by leaving a comment here without comma at the end"]
 ]