[Haskell-cafe] Improvements to package hosting and security

Michael Snoyman michael at snoyman.com
Wed Apr 15 04:34:45 UTC 2015

On Wed, Apr 15, 2015 at 5:56 AM Carter Schonwald <carter.schonwald at gmail.com>

> any use of cryptographic primitives of any form NEEDS to articulate what
> the trust model is, and what the threat model is
> likewise, i'm trying to understand who the proposed feature set is meant
> to serve.
> Several groups are in the late stages of building prototypes at varying
> points in the design space for improving package hosting right now for
> haskell, and I'm personally inclined to let those various parties release
> the tools, and then experiment with them all, before trying to push heavily
> for any particular design that hasn't had larger community experimentation.
I'd be fine with that, if there was public discussion of what those
projects are trying to solve. Of the ones that I have asked questions
about, I haven't heard any of them trying to address the trust/security
issues I've raised here, which is why I'm asking the mailing list if
there's interest.

I'm not OK with simply stalling any community process for improving our
situation because "someone's working on something related, and it'll be
done Real Soon Now(tm)." That's a recipe for stagnation.

> I actually care most about being able to have the full package set be git
> cloneable, both for low pain on premise hackage hosting for corporate
> intranets, and also for when i'm on a plane or boat and have no wifi.  At
> my current job, ANY "host packages via s3" approach is totally untenable,
> and i'm sure among haskell using teams/organizations, this isn't a unique
> problem!
I agree completely. And similarly, hosting all packages in a Git repository
is *also* unusable in other situations, such as normal users wanting to get
a minimal set of downloads to get started on a project. That's why I left
the download information in this proposal at URL; you can add different
URLs to support Git repository contents as well.

It would also be pretty easy to modify the all-cabal-files repo I pointed
to and create a repository containing the tarballs themselves. I don't know
if Github would like hosting that much content, but I have no problem
helping roll that out.

> The Author authentication/signing model question in an important one, but
> I"m uncomfortable with just saying "SHA512 and GPG address that". Theres A
> LOT of subtlety to designing a signing protocol thats properly audit-able
> and secure! Indeed, GPG isn't even a darn asymmetric crypto algorithm, its
> a program that happens to IMPLEMENT many of these algorithms. If we are
> serious about having robust auditing/signing, handwaving about the
> cryptographic parts while saying its important is ... kinda irresponsible.
> And frustrating because it makes it hard to evaluate the hardest parts of
> the whole engineering problem!  The rest of the design is crucially
> dependent on details of  these choices, and yet its that part which isn't
> specified.
I think you're assuming that my "proposal" was more than a point of
discussion. It's not. When starting this thread, I tried to make it clear
that this is to gauge interest in creating a real solution. If there's
interest, we should figure out these points. If there's no interest, then
I'm glad I didn't invest weeks in coming up with a more robust proposal.

> to repeat myself: there is a pretty rich design space for how we can
> evolve future hackage, and i worry that speccing things out and design by
> committee is going to be less effective than encouraging various parties to
> build prototypes for their own visions of future hackage, and THEN come
> together to combine the best parts of everyones ideas/designs. Theres so
> much diversity in how different people use hackage, i worry that any other
> way will run into failing to serve the full range of haskell users!
I disagree here pretty strongly. Something with a strong social element
requires discussion upfront, not someone creating a complete solution and
then trying to impose it on everyone else. There are certainly things that
*can* be done without discussion. Hosting cabal and tar.gz files in a Git
repo, or mirroring to S3, are orthogonal actions that require no
coordination, for instance. But tweaking the way we view the trust model of
Hackage is pretty central, and needs discussion.


> cheers
> On Tuesday, April 14, 2015 at 1:01:17 AM UTC-4, Michael Snoyman wrote:
>> That could work in theory. My concern with such an approach is that-
>> AFAIK- the tooling around that kind of stuff is not very well developed, as
>> opposed to an approach using Git, SHA512, and GPG, which should be easy to
>> combine. But I could be completely mistaken on this point; if existing,
>> well vetted technology exists for this, I'm not opposed to using it.
>> On Mon, Apr 13, 2015 at 6:04 PM Arnaud Bailly | Capital Match <
>> arn... at capital-match.com> wrote:
> Just thinking aloud but wouldn't it be possible to take advantage of
>>> cryptographic ledgers a la Bitcoin for authenticating packages and tracking
>>> the history of change ? This would provide redundancy as the transactions
>>> log is distributed and "naturally" create a web of trust or at least
>>> authenticate transactions. People uploading or modifying a package would
>>> have to sign a transactions with someone having enough karma to allow this.
>>> Then packages themselves could be completely and rather safely
>>> distributed through standard p2p file sharing.
>>> I am not a specialist of crypto money, though.
>>> My 50 cts
>>> Arnaud
>>> Le lundi 13 avril 2015, Dennis J. McWherter, Jr. <den... at deathbytape.com>
>>> a écrit :
>>>> This proposal looks great. The one thing I am failing to understand
>>>> (and I recognize the proposal is in early stages) is how to ensure
>>>> redundancy in the system. As far as I can tell, much of this proposal
>>>> discusses the centralized authority of the system (i.e. ensuring secure
>>>> distribution) and only references (with little detail) the distributed
>>>> store. For instance, say I host a package on a personal server and one day
>>>> I decide to shut that server down; is this package now lost forever? I do
>>>> see this line: "backup download links to S3" but this implies that the
>>>> someone is willing to pay for S3 storage for all of the packages.
>>>> Are there plans to adopt a P2P-like model or something similar to
>>>> support any sort of replication? Public resources like this seem to come
>>>> and go, so it would be nice to avoid some of the problems associated with
>>>> high churn in the network. That said, there is an obvious cost to
>>>> replication. Likewise, the central authority would have to be updated with
>>>> new, relevant locations to find the file (as it is currently proposed).
>>>> In any case, as I said before, the proposal looks great! I am looking
>>>> forward to this.
>>>> On Monday, April 13, 2015 at 5:02:46 AM UTC-5, Michael Snoyman wrote:
>>>>> Many of you saw the blog post Mathieu wrote[1] about having more
>>>>> composable community infrastructure, which in particular focused on
>>>>> improvements to Hackage. I've been discussing some of these ideas with both
>>>>> Mathieu and others in the community working on some similar thoughts. I've
>>>>> also separately spent some time speaking with Chris about package
>>>>> signing[2]. Through those discussions, it's become apparent to me that
>>>>> there are in fact two core pieces of functionality we're relying on Hackage
>>>>> for today:
>>>>> * A centralized location for accessing package metadata (i.e., the
>>>>> cabal files) and the package contents themselves (i.e., the sdist tarballs)
>>>>> * A central authority for deciding who is allowed to make releases of
>>>>> packages, and make revisions to cabal files
>>>>> In my opinion, fixing the first problem is in fact very
>>>>> straightforward to do today using existing tools. FP Complete already hosts
>>>>> a full Hackage mirror[3] backed by S3, for instance, and having the
>>>>> metadata mirrored to a Git repository as well is not a difficult technical
>>>>> challenge. This is the core of what Mathieu was proposing as far as
>>>>> composable infrastructure, corresponding to next actions 1 and 3 at the end
>>>>> of his blog post (step 2, modifying Hackage, is not a prerequesite). In my
>>>>> opinion, such a system would far surpass in usability, reliability, and
>>>>> extensibility our current infrastructure, and could be rolled out in a few
>>>>> days at most.
>>>>> However, that second point- the central authority- is the more
>>>>> interesting one. As it stands, our entire package ecosystem is placing a
>>>>> huge level of trust in Hackage, without any serious way to vet what's going
>>>>> on there. Attack vectors abound, e.g.:
>>>>> * Man in the middle attacks: as we are all painfully aware,
>>>>> cabal-install does not support HTTPS, so a MITM attack on downloads from
>>>>> Hackage is trivial
>>>>> * A breach of the Hackage Server codebase would allow anyone to upload
>>>>> nefarious code[4]
>>>>> * Any kind of system level vulnerability could allow an attacker to
>>>>> compromise the server in the same way
>>>>> Chris's package signing work addresses most of these vulnerabilities,
>>>>> by adding a layer of cryptographic signatures on top of Hackage as the
>>>>> central authority. I'd like to propose taking this a step further: removing
>>>>> Hackage as the central authority, and instead relying entirely on
>>>>> cryptographic signatures to release new packages.
>>>>> I wrote up a strawman proposal last week[5] which clearly needs work
>>>>> to be a realistic option. My question is: are people interested in moving
>>>>> forward on this? If there's no interest, and everyone is satisfied with
>>>>> continuing with the current Hackage-central-authority, then we can proceed
>>>>> with having reliable and secure services built around Hackage. But if
>>>>> others- like me- would like to see a more secure system built from the
>>>>> ground up, please say so and let's continue that conversation.
>>>>> [1] https://www.fpcomplete.com/blog/2015/03/composable-
>>>>> community-infrastructure
>>>>> [2] https://github.com/commercialhaskell/commercialhaskell/wiki/
>>>>> Package-signing-detailed-propsal
>>>>> [3] https://www.fpcomplete.com/blog/2015/03/hackage-mirror
>>>>> [4] I don't think this is just a theoretical possibility for some
>>>>> point in the future. I have reported an easily trigerrable DoS attack on
>>>>> the current Hackage Server codebase, which has been unresolved for 1.5
>>>>> months now
>>>>> [5] https://gist.github.com/snoyberg/732aa47a5dd3864051b9
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>>> --
>> *Arnaud Bailly*
>>> CTO | Capital Match
>>> CapitalMatch
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