[Distutils] [tuf] Re: vetting, signing, verification of release files

[Justin Cappos]

My impression is this only holds for things signed directly by PyPI because
the developers have not registered a key.   I think that developers who
register keys won't have this issue.  Let's talk about this when you
return, but it's really projects / developers that will be stable in the
common case, not packages, right?

Justin


On Wed, Jul 17, 2013 at 9:29 PM, Trishank Karthik Kuppusamy <
tk47 at students.poly.edu> wrote:

> On 07/18/2013 03:24 AM, Ronald Oussoren wrote:
>
>> I'm trying to understand what this means for package maintainers. If I
>> understand you correctly maintainers would upload packages just like they
>> do now, and packages are then automaticly signed by the "unstable" role.
>>  Then some manual process by the PyPI maintainers can sign a package with a
>> stable row. Is that correct? If it is, how is this supposed to scale? The
>> contents of PyPI is currently not vetted at all, and it seems to me that
>> manually vetting uploads for even the most popular packages would be a
>> significant amount of work that would have to be done by what's likely a
>> small set of volunteers.
>>
>
> I think Daniel put it best when he said that we have been focusing too
> much on deciding whether or not a package is malicious. As he said, it is
> important that any security proposal must limit what targeted attacks on
> the PyPI infrastructure can do.
>
> You are right that asking people to vet through packages for inclusion
> into the stable role would be generally unscalable. I think the best way to
> think about it is that we can mostly decide a "stable" set of packages with
> a simple rule, and then *choose* to interfere (if necessary) with decisions
> on which packages go in or out of the stable role. The stable role simply
> has to sign this automatically computed set of "stable" packages every now
> and then, so that the impacts of attacks on the PyPI infrastructure are
> limited. Users who install the same set of stable packages will see the
> installation of the same set of intended packages.
>
> Presently, I use a simple heuristic to compute a nominal set of stable
> packages: all files older than 3 months are considered to be "stable".
> There is no consideration of whether a package is malicious here; just that
> it has not changed long enough to be considered mature.
>
>
>  Also, what are you supposed to do when FooBar 2.0 is signed by the stable
>> role and FooBar 2.0.1 is only signed by the unstable role, and you try to
>> fetch FooBar 2.0.* (that is, 2.0 or any 2.0.x point release)?
>>
>>
> In this case, I expect that since we have asked pip to install FooBar
> 2.0.*, it will first fetch the /simple/FooBar/ PyPI metadata (distinct from
> TUF metadata) to see what versions of the FooBar package are available. If
> FooBar 2.0.1 was recently added, then the latest version of the
> /simple/FooBar/ metadata would have been signed for the unstable role.
> There are two cases for the stable role:
>
> 1. The stable role has also signed for the FooBar 2.0.1 package. In this
> case, pip would find FooBar 2.0.1 and install it.
> 2. The stable role has not yet signed for the FooBar 2.0.1 package. In
> this case, pip would find FooBar 2.0 and install it.
>
> Why would this happen? In this case, we have specified in the TUF metadata
> that if the same file (in this case, the /simple/FooBar/ HTML file) has
> been signed for by both the stable and unstable roles, then the client must
> prefer the version from the stable role.
>
> Of course, there are questions about timeliness. Sometimes users want the
> latest packages, or the developers of the packages themselves may want this
> to be the case. For the purposes of bootstrapping PyPI with TUF, we have
> presently decided to simplify key management and allow for the protection
> of some valuable packages on PyPI (with limited timeliness trade-off) while
> allowing for the majority of the packages to be continuously released.
>
> There are a few ways to ensure that the latest intended versions of the
> FooBar package will be installed:
> 1. Do not nominate FooBar into the "stable" set of packages, which should
> ideally be reserved --- for initial bootstrapping purposes at least --- for
> perhaps what the community thinks are the "canonical" packages that must
> initially be protected from attacks.
> 2. The stable role may delegate its responsibility about information on
> the FooBar package to the FooBar package developers themselves.
> 3. Explore different rules (other than just ordering roles by trust) to
> balance key management, timeliness and other issues without significantly
> sacrificing security.
>
> We welcome your thoughts here. For the moment, we are planning to wrap up
> as soon as possible our experiments on how PyPI+pip perform with and
> without TUF with this particular scheme of stable and unstable roles.
>
>
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