From: Brandon Williams <bmwill@google.com>
To: Jonathan Tan <jonathantanmy@google.com>
Cc: Junio C Hamano <gitster@pobox.com>,
git@vger.kernel.org, markbt@efaref.net, git@jeffhostetler.com,
kevin.david@microsoft.com
Subject: Re: Proposal for missing blob support in Git repos
Date: Mon, 1 May 2017 17:38:27 -0700 [thread overview]
Message-ID: <20170502003827.GB154031@google.com> (raw)
In-Reply-To: <c0c8a0c3-582c-cf3b-3833-c918a0630f9f@google.com>
On 05/01, Jonathan Tan wrote:
> On 05/01/2017 04:29 PM, Junio C Hamano wrote:
> >Jonathan Tan <jonathantanmy@google.com> writes:
> >
> >>Thanks for your comments. If you're referring to the codepath
> >>involving write_sha1_file() (for example, builtin/hash-object ->
> >>index_fd or builtin/unpack-objects), that is fine because
> >>write_sha1_file() invokes freshen_packed_object() and
> >>freshen_loose_object() directly to check if the object already exists
> >>(and thus does not invoke the new mechanism in this patch).
> >
> >Is that a good thing, though? It means that you an attacker can
> >feed one version to the remote object store your "grab blob" hook
> >gets the blobs from, and have you add a colliding object locally,
> >and the usual "are we recording the same object as existing one?"
> >check is bypassed.
>
> If I understand this correctly, what you mean is the situation where
> the hook adds an object to the local repo, overriding another object
> of the same name? If yes, I think that is the nature of executing an
> arbitrary command. If we really want to avoid that, we could drop
> the hook functionality (and instead, for example, provide the URL of
> a Git repo instead from which we can communicate using a new
> fetch-blob protocol), although that would reduce the usefulness of
> this, especially during the transition period in which we don't have
> any sort of batching of requests.
If I understand correctly this is where we aim to be once all is said
and done. I guess the question is what are we willing to do during the
transition phase.
--
Brandon Williams
next prev parent reply other threads:[~2017-05-02 0:38 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-26 22:13 Proposal for missing blob support in Git repos Jonathan Tan
2017-05-01 3:57 ` Junio C Hamano
2017-05-01 19:12 ` Jonathan Tan
2017-05-01 23:29 ` Junio C Hamano
2017-05-02 0:33 ` Jonathan Tan
2017-05-02 0:38 ` Brandon Williams [this message]
2017-05-02 1:41 ` Junio C Hamano
2017-05-02 17:21 ` Jonathan Tan
2017-05-02 18:32 ` Ævar Arnfjörð Bjarmason
2017-05-02 21:45 ` Jonathan Tan
2017-05-04 4:29 ` Junio C Hamano
2017-05-04 17:09 ` Jonathan Tan
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