Re: [Sks-devel] simple DoS against SKS's HKP interface :/

[John Clizbe]

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Johan van Selst wrote:
> Daniel Kahn Gillmor wrote:
>> Fix?
>> ----
>> I'm afraid i don't know ocaml at all, so i don't have a proposed fix.
>> It seems to be related to the event loop model on the sks db process,
>> though.  Looking at it from a system call level: either sks should be
>> multi-threaded, or reads from network sockets should be non-blocking,
>> and bundled into an aggregate select() statement so that concurrent
>> requests can be properly interleaved.
> 
> This seems to be the best way forward. Is anybody on this list actually
> looking into the suggested solution? Most people here, myself included,
> don't seem to be very fluent in OCaml programming. But I would
> definately appreciate it if somebody could look into this and come up
> with a real fix, rather than best-practice workarounds with reverse
> webproxies.

Oddly, I was looking at a different problem last night and noticed this
snippet appearing twice in wserver.ml:

188-189
let rec parse_headers map cin =
  let line = input_line cin in (* DOS attack: input_line is unsafe on
sockets *)

201-202
let parse_request cin =
  let line = input_line cin in (* DOS attack: input_line is unsafe on
sockets *)

So, it would appear to my barely apprentice level OCaml, that our
solution lies in a socket-safe implementation of input_line

- -John
- -- 
John P. Clizbe                      Inet: John (a) Gingerbear DAWT net
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