Messages in this thread | | | Date | Fri, 23 Dec 2016 12:59:59 +0100 | From | Daniel Borkmann <> | Subject | Re: BPF hash algo (Re: [kernel-hardening] Re: [PATCH v7 3/6] random: use SipHash in place of MD5) |
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On 12/23/2016 11:59 AM, Hannes Frederic Sowa wrote: > On Fri, 2016-12-23 at 11:04 +0100, Daniel Borkmann wrote: >> On 12/22/2016 05:59 PM, Hannes Frederic Sowa wrote: >>> On Thu, 2016-12-22 at 08:07 -0800, Andy Lutomirski wrote: [...] >>> The hashing is not a proper sha1 neither, unfortunately. I think that >>> is why it will have a custom implementation in iproute2? >> >> Still trying to catch up on this admittedly bit confusing thread. I >> did run automated tests over couple of days comparing the data I got >> from fdinfo with the one from af_alg and found no mismatch on the test >> cases varying from min to max possible program sizes. In the process >> of testing, as you might have seen on netdev, I found couple of other >> bugs in bpf code along the way and fixed them up as well. So my question, >> do you or Andy or anyone participating in claiming this have any >> concrete data or test cases that suggests something different? If yes, >> I'm very curious to hear about it and willing fix it up, of course. >> When I'm back from pto I'll prep and cook up my test suite to be >> included into the selftests/bpf/, should have done this initially, >> sorry about that. I'll also post something to expose the alg, that >> sounds fine to me. > > Looking into your code closer, I noticed that you indeed seem to do the > finalization of sha-1 by hand by aligning and padding the buffer > accordingly and also patching in the necessary payload length. > > Apologies for my side for claiming that this is not correct sha1 > output, I was only looking at sha_transform and its implementation and > couldn't see the padding and finalization round with embedding the data > length in there and hadn't thought of it being done manually. > > Anyway, is it difficult to get the sha finalization into some common > code library? It is not very bpf specific and crypto code reviewers > won't find it there at all.
Yes, sure, I'll rework it that way (early next year when I'm back if that's fine with you).
Thanks, Daniel
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