[tor-dev] prop224: What should we do with torrc options?

[teor]

> On 25 Nov. 2016, at 03:40, David Goulet <dgoulet at ev0ke.net> wrote:
> 
> On 24 Nov (11:13:06), teor wrote:
>> 
>>> On 24 Nov. 2016, at 11:04, Yawning Angel <yawning at schwanenlied.me> wrote:
>>> 
>>> On Thu, 24 Nov 2016 01:43:15 +0200
>>> s7r <s7r at sky-ip.org> wrote:
>>>> I agree that this would be "the technical way" to do it, but real
>>>> world usability kind of prevents us to do it this way. The spec for
>>>> ADD_ONION indeed does not say that v2 hidden services will be
>>>> supported forever and it clearly SHOULD NOT, but it also doesn't make
>>>> much sense to abolish it at the first Tor release supporting v3
>>>> services (because if we make ADD_ONION == v3 (best) this is what we
>>>> are doing).
>>> 
>>> Even I don't think `BEST` should be changed to Ed25519 immediately,
>>> especially when the code is being stabilized.
>> 
>> So I think we should have an option:
>> 
>> OnionServiceCreateV3 0|1
> 
> Few things why I'm not too keen with this even though it could actually be
> very useful... I'll outline the potential issues here with such an option but
> unfortunately I don't have a perfect solution in the end. My main concern is
> not really an easy or intuitive way for the user to start using v3 service but
> rather when the users will start using it, the network MUST be ready for it
> which makes things a bit more complicated to do properly I believe.
> 
> Considering a torrc option such as "OnionServiceCreateV3 0|1":
> 
> 1) This is extremely non intuitive to any operator even power users. The
>   concept of "v3" is something that very few people will understand what it's
>   actually is. Even if we go with "OnionServiceEpicNextMoreSecureGeneration
>   1", we are creating two classes of onion service that will make things more
>   confusing for the user with the question of "which one should I use?". Also
>   see 3 below for more confusion.

We are already creating two classes of onion service: they have significantly
different user-visible addresses, client authentication, and Tor version
requirements.

This option simply controls which version is created by default when the user
asks for an onion service.

But we already have a HiddenServiceVersion option, let's use that, and make
the default:

For at least one release:
* whatever the existing service uses, or
* 2 for new services (with 3 being an alternative),

For at least one more release:
* whatever the existing service uses (with 2 being deprecated),
* 3 for new services (with 2 being deprecated),

For at least one more release:
* whatever the existing service uses (with 2 being deprecated),
* 3 for new services (with 2 being deprecated, and only able to be created
  manually),

For releases after that:
* make the default and only version 3.

Do we support the same service publishing version 2 and version 3
descriptors?

Or do we expect people to set up two different services and direct them to
the same port?
Do we want to keep that option as a list for future use?

Either way, we should document that in the man page.

Since there's a default, most users will never set it, and they will just
see the default for new services change in a particular release, and then
another release where old services are deprecated, and then they will be gone
entirely.

> 2) It also means we create an option that will get deprecated once v2 is
>   phased out so we are adding a "temporary" option for users to "keep
>   creating v2 addresses" but then will be useless and we'll deprecate and get
>   a whole lot confusing if for instance v4 or v5 happens in the next years
>   for X reasons (unlikely but not impossible).

Not if we use the existing HiddenServiceVersion option for this.

Here are the use cases for this option:
* a developer wants to test that their software works with V3 onion services,
  before the default is changed,
* a user wants to run their old software with V2 onion services, after the
  default is changed.

> 3) The current plan so far is to add a consensus parameter that will control
>   the switch for client and service to start using prop224. And every relay
>   out there that will run a tor supporting the v3 protocol (HSDir, IP, RP)
>   will speak the protocol no matter what. So then we can decide when the
>   network is mature enough for client/service to start talking actively that
>   protocol.
> 
>   That switch will also be an opportunity for us to remove v0 and v1 support
>   as well from tor making that event "The Big Onion Service Switch" or for
>   short "The BOSS (tm)" :P.
> 
>   HOWEVER, the hard part here is getting that consensus param information
>   about the state of prop224 _before_ configuring your HS.... it's doable but
>   will weirdly make a specific tor version bootstrap HS much slower as
>   they'll have to wait for the consensus to be downloaded.... maybe there is
>   a better way?
> 
> Here is an idea, we could rely on a tor version for enabling the feature
> instead that is we release client/service support when and only when the
> network is mature so then there will be no confusion, you run version X, you
> get v3, period, the network is ready. That is again not ideal as we then delay
> this important new feature by some unknown chunks of 6 months... but at least
> we have some assurance that it's ready.
> 
> We can ship the code in let's say 031 but make tor only use it in 032 for
> instance.
> 
> …

I think the consensus parameter is more useful as an emergency on/off
switch for descriptor publication, not service configuration.

If the code exists on the client, a user should always be able to configure a v3
onion service. Even before the consensus is downloaded. Even if they do not have
access to the network.

So here's how I'd use the consensus parameter:
* if the consensus parameter says v3 services are disabled, users can configure
  a v3 service, but it will warn and refuse to publish its descriptor. 
* if the consensus parameter says v3 services are enabled, users can configure
  a v3 service, and it will publish its descriptor.
  (And we should be able to deprecate v3 at some point in the future.)

And similarly for v2:
* if the consensus parameter says v2 services are enabled, users can configure
  a v2 service, and it will publish its descriptor. 
* if the consensus parameter says v2 services are deprecated, users can
  configure a v2 service, and it will warn, and then publish its descriptor.
* if the consensus parameter says v2 services are disabled, users can configure
  a v2 service, but it will warn and refuse to publish its descriptor.
  (And some future Tor version will remove support for creating v2 services,
   and another version will remove support for loading them.)

We should also consider how this interacts with the protocol lines in the
consensus.

T

-- 
Tim Wilson-Brown (teor)

teor2345 at gmail dot com
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