Hi Reyk
On 11.07.2014, at 17:29, Reyk Floeter <[email protected]> wrote:
> On Wed, Jul 02, 2014 at 01:34:51PM +0200, Markus Gebert wrote:
>> I hope this is the right mailing list to publish a patch. If not,
>> please let me know where to place it or how I should get in contact
>> with the relayd maintainer(s).
>>
>> I've added some new SSL features and config options to relayd that we
>> needed at work:
>>
>> - ssl edh params "value"
>> -> allows to control the use of OpenSSL built-in DH params. With
>> them, relayd is now able to use EDH/DHE ciphers. They are the
>> only option to provide forward secrecy for older clients.
>>
>> - ssl [no] cipher-server-preference
>> -> allows the admin to control SSL_OP_CIPHER_SERVER_PREFERENCE to be
>> able to force some cipher preferences on clients (i.e. to prefer
>> ciphers that provide forward secrecy).
>>
>> - ssl [no] client-renegotiation
>> -> allows the interception of ("secure") client initiated
>> renegotioations, which are considered a risk in DDoS scenarios
>> because many CPU cycles can be burned this way on a single TCP
>> connection without an obvious way for the administrator to
>> immediately know what's happening.
>>
>>
>> The patch was originally written against the FreeBSD port of relayd, but
>> since all the changes should be easily portable to OpenBSD and it makes
>> sense to add the features upstream, I recreated the patch so that it
>> applies to OpenBSD (5.5 and CURRENT). It's only compile-tested, but the
>> changed code parts do not really differ between the platforms, so I
>> think the patch should be safe to use.
>>
>> Patch for OpenBSD 5.5:
>> http://gebert.net/share/relayd-ssl-5.5.diff
>>
>> Patch for OpenBSD CURRENT as of 2014-07-01:
>> http://gebert.net/share/relayd-ssl-current-20140701.diff
>>
>>
>> Please feel free to change any defaults I’ve chosen for the new config
>> options. They were chosen for the environmet I run relayd in and might
>> not fit your policies about introducing new features.
>>
>> Any feedback is welcome!
>>
>
> Thank you for the diff, I updated the diff and changed a few defaults
> after discussing them with jsing@. I also adjusted the grammar a
> little bit to the following style (also for ecdh):
>
> ssl edh - enable edh with the default maximum of 1024
> bits
> ssl no edh - disable edh (the default, provided for consistency)
> ssl edh params 8192 - set a non-default maximum
>
> I removed the "auto" option because providing 8192 will effectively be
> the same. I also adjusted the ecdh option accordingly:
>
> ssl ecdh - enable ecdh (the default, using prime256v1)
> ssl no ecdh - disable ecdh
> ssl ecdh curve prime256v1 - set a specific curve
>
> The other options cipher-server-preference and client-renegotiation
> make sense, but I changed it to allow "client-renegotiation" by
> default - I want to avoid too many differences to the standard SSL
> library. Please note that relayd is now developed for LibreSSL where
> more defaults might be different to OpenSSL in the future.
Thanks, the new diff looks good to me. I actually like the new grammar
style much more, I was just trying to stick close to the one ecdh used,
but if you change both, the new style makes much more sense. I expected
that you would change the default for client initiated renegotiations,
so I'm good with that too.
I have another diff, which improves the SSL error handling code in
relayd, but I want to discuss that off-list first, if that's ok with
you.
Markus
