From ec389a30e5242e4cc4fd24aab4d383f685617956 Mon Sep 17 00:00:00 2001 From: Peter Todd Date: Mon, 10 Mar 2014 17:36:35 -0400 Subject: [PATCH] Add rejection of non-null CHECKMULTISIG dummy values This is a source of transaction mutability as the dummy value was previously not checked and could be modified to something other than the usual OP_0 value. --- src/script.cpp | 16 +++++++++++++++- src/script.h | 4 +++- src/test/data/tx_invalid.json | 29 ++++++++++++++++++++++++++++- src/test/data/tx_valid.json | 18 ++++++++++++++++-- src/test/transaction_tests.cpp | 1 + 5 files changed, 63 insertions(+), 5 deletions(-) diff --git a/src/script.cpp b/src/script.cpp index 10d79e649..1e6e0e5d0 100644 --- a/src/script.cpp +++ b/src/script.cpp @@ -923,8 +923,22 @@ bool EvalScript(vector >& stack, const CScript& script, co fSuccess = false; } - while (i-- > 0) + // Clean up stack of actual arguments + while (i-- > 1) popstack(stack); + + // A bug causes CHECKMULTISIG to consume one extra argument + // whose contents were not checked in any way. + // + // Unfortunately this is a potential source of mutability, + // so optionally verify it is exactly equal to zero prior + // to removing it from the stack. + if (stack.size() < 1) + return false; + if ((flags & SCRIPT_VERIFY_NULLDUMMY) && stacktop(-1).size()) + return error("CHECKMULTISIG dummy argument not null"); + popstack(stack); + stack.push_back(fSuccess ? vchTrue : vchFalse); if (opcode == OP_CHECKMULTISIGVERIFY) diff --git a/src/script.h b/src/script.h index f6e5f045a..3a8717986 100644 --- a/src/script.h +++ b/src/script.h @@ -190,6 +190,7 @@ enum SCRIPT_VERIFY_STRICTENC = (1U << 1), // enforce strict conformance to DER and SEC2 for signatures and pubkeys SCRIPT_VERIFY_EVEN_S = (1U << 2), // enforce even S values in signatures (depends on STRICTENC) SCRIPT_VERIFY_NOCACHE = (1U << 3), // do not store results in signature cache (but do query it) + SCRIPT_VERIFY_NULLDUMMY = (1U << 4), // verify dummy stack item consumed by CHECKMULTISIG is of zero-length }; // Mandatory script verification flags that all new blocks must comply with for @@ -202,7 +203,8 @@ static const unsigned int MANDATORY_SCRIPT_VERIFY_FLAGS = SCRIPT_VERIFY_P2SH; // with. However scripts violating these flags may still be present in valid // blocks and we must accept those blocks. static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS | - SCRIPT_VERIFY_STRICTENC; + SCRIPT_VERIFY_STRICTENC | + SCRIPT_VERIFY_NULLDUMMY; enum txnouttype { diff --git a/src/test/data/tx_invalid.json b/src/test/data/tx_invalid.json index b9472ce00..638a705f9 100644 --- a/src/test/data/tx_invalid.json +++ b/src/test/data/tx_invalid.json @@ -67,11 +67,38 @@ ["0000000000000000000000000000000000000000000000000000000000000200", 0, "0x21 0x035e7f0d4d0841bcd56c39337ed086b1a633ee770c1ffdd94ac552a95ac2ce0efc CHECKSIG"]], "01000000020001000000000000000000000000000000000000000000000000000000000000000000004948304502203a0f5f0e1f2bdbcd04db3061d18f3af70e07f4f467cbc1b8116f267025f5360b022100c792b6e215afc5afc721a351ec413e714305cb749aae3d7fee76621313418df10101000000000200000000000000000000000000000000000000000000000000000000000000000000484730440220201dc2d030e380e8f9cfb41b442d930fa5a685bb2c8db5906671f865507d0670022018d9e7a8d4c8d86a73c2a724ee38ef983ec249827e0e464841735955c707ece98101000000010100000000000000015100000000", "P2SH"], -["Incorrect signature order"], +["CHECKMULTISIG with incorrect signature order"], ["Note the input is just required to make the tester happy"], [[["b3da01dd4aae683c7aee4d5d8b52a540a508e1115f77cd7fa9a291243f501223", 0, "HASH160 0x14 0xb1ce99298d5f07364b57b1e5c9cc00be0b04a954 EQUAL"]], "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", "P2SH"], + +["The following is a tweaked form of 23b397edccd3740a74adb603c9756370fafcde9bcc4483eb271ecad09a94dd63"], +["It is an OP_CHECKMULTISIG with the dummy value missing"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba260000000004847304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH"], + + +["CHECKMULTISIG SCRIPT_VERIFY_NULLDUMMY tests:"], + +["The following is a tweaked form of 23b397edccd3740a74adb603c9756370fafcde9bcc4483eb271ecad09a94dd63"], +["It is an OP_CHECKMULTISIG with the dummy value set to something other than an empty string"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba260000000004a010047304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH,NULLDUMMY"], + +["As above, but using a OP_1"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba26000000000495147304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH,NULLDUMMY"], + +["As above, but using a OP_1NEGATE"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba26000000000494f47304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH,NULLDUMMY"], + +["As above, but with the dummy byte missing"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba260000000004847304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH,NULLDUMMY"], + + ["Empty stack when we try to run CHECKSIG"], [[["ad503f72c18df5801ee64d76090afe4c607fb2b822e9b7b63c5826c50e22fc3b", 0, "0x21 0x027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5 CHECKSIG NOT"]], "01000000013bfc220ec526583cb6b7e922b8b27f604cfe0a09764de61e80f58dc1723f50ad0000000000ffffffff0101000000000000002321027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5ac00000000", "P2SH"], diff --git a/src/test/data/tx_valid.json b/src/test/data/tx_valid.json index ddcb12ff1..1f51d3ce5 100644 --- a/src/test/data/tx_valid.json +++ b/src/test/data/tx_valid.json @@ -13,9 +13,23 @@ "0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba26000000000490047304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH"], ["The following is a tweaked form of 23b397edccd3740a74adb603c9756370fafcde9bcc4483eb271ecad09a94dd63"], -["It has an arbitrary extra byte stuffed into the signature at pos length - 2"], +["It is an OP_CHECKMULTISIG with an arbitrary extra byte stuffed into the signature at pos length - 2"], +["The dummy byte is fine however, so the NULLDUMMY flag should be happy"], [[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], -"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba260000000004A0048304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2bab01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH"], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba260000000004A0048304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2bab01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH,NULLDUMMY"], + +["The following is a tweaked form of 23b397edccd3740a74adb603c9756370fafcde9bcc4483eb271ecad09a94dd63"], +["It is an OP_CHECKMULTISIG with the dummy value set to something other than an empty string"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba260000000004a01ff47304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH"], + +["As above, but using a OP_1"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba26000000000495147304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH"], + +["As above, but using a OP_1NEGATE"], +[[["60a20bd93aa49ab4b28d514ec10b06e1829ce6818ec06cd3aabd013ebcdc4bb1", 0, "1 0x41 0x04cc71eb30d653c0c3163990c47b976f3fb3f37cccdcbedb169a1dfef58bbfbfaff7d8a473e7e2e6d317b87bafe8bde97e3cf8f065dec022b51d11fcdd0d348ac4 0x41 0x0461cbdcc5409fb4b4d42b51d33381354d80e550078cb532a34bfa2fcfdeb7d76519aecc62770f5b0e4ef8551946d8a540911abe3e7854a26f39f58b25c15342af 2 OP_CHECKMULTISIG"]], +"0100000001b14bdcbc3e01bdaad36cc08e81e69c82e1060bc14e518db2b49aa43ad90ba26000000000494f47304402203f16c6f40162ab686621ef3000b04e75418a0c0cb2d8aebeac894ae360ac1e780220ddc15ecdfc3507ac48e1681a33eb60996631bf6bf5bc0a0682c4db743ce7ca2b01ffffffff0140420f00000000001976a914660d4ef3a743e3e696ad990364e555c271ad504b88ac00000000", "P2SH"], ["The following is c99c49da4c38af669dea436d3e73780dfdb6c1ecf9958baa52960e8baee30e73"], ["It is of interest because it contains a 0-sequence as well as a signature of SIGHASH type 0 (which is not a real type)"], diff --git a/src/test/transaction_tests.cpp b/src/test/transaction_tests.cpp index 1796edda0..8ffa8b128 100644 --- a/src/test/transaction_tests.cpp +++ b/src/test/transaction_tests.cpp @@ -39,6 +39,7 @@ unsigned int ParseFlags(string strFlags){ mapFlagNames["P2SH"] = SCRIPT_VERIFY_P2SH; mapFlagNames["STRICTENC"] = SCRIPT_VERIFY_STRICTENC; mapFlagNames["EVEN_S"] = SCRIPT_VERIFY_EVEN_S; + mapFlagNames["NULLDUMMY"] = SCRIPT_VERIFY_NULLDUMMY; } BOOST_FOREACH(string word, words)