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From: Stefan Beller <sbeller@google.com>
To: Jonathan Nieder <jrnieder@gmail.com>
Cc: Brandon Williams <bmwill@google.com>, Jeff King <peff@peff.net>,
	git <git@vger.kernel.org>
Subject: Re: [PATCH 2/2] submodule: munge paths to submodule git directories
Date: Tue, 14 Aug 2018 14:08:01 -0700
Message-ID: <CAGZ79kZUq5jPqyb=B1ppEi1QhNGmhLXeV6vPn8ouR=YGEN32pg@mail.gmail.com> (raw)
In-Reply-To: <20180814185743.GE142615@aiede.svl.corp.google.com>

On Tue, Aug 14, 2018 at 11:57 AM Jonathan Nieder <jrnieder@gmail.com> wrote:
>
> Hi,
>
> Brandon Williams wrote:
> > On 08/09, Jeff King wrote:
>
> >> One interesting thing about url-encoding is that it's not one-to-one.
> >> This case could also be %2F, which is a different file (on a
> >> case-sensitive filesystem). I think "%20" and "+" are similarly
> >> interchangeable.
> >>
> >> If we were decoding the filenames, that's fine. The round-trip is
> >> lossless.
> >>
> >> But that's not quite how the new code behaves. We encode the input and
> >> then check to see if it matches an encoding we previously performed. So
> >> if our urlencode routines ever change, this will subtly break.
> >>
> >> I don't know how much it's worth caring about. We're not that likely to
> >> change the routines ourself (though certainly a third-party
> >> implementation would need to know our exact url-encoding decisions).
> >
> > This is exactly the reason why I wanted to get some opinions on what the
> > best thing to do here would be.  I _think_ the best thing would probably
> > be to write a specific routine to do the conversion, and it wouldn't
> > even have to be all that complex.  Basically I'm just interested in
> > converting '/' characters so that things no longer behave like
> > nested directories.
>
> First of all, I think the behavior with this patch is already much
> better than the previous status quo.  I'm using the patch now and am
> very happy with it.
>
> Second, what if we store the pathname in config?  We already store the
> URL there:
>
>         [submodule "plugins/hooks"]
>                 url = https://gerrit.googlesource.com/plugins/hooks
>
> So we could (as a followup patch) do something like
>
>         [submodule "plugins/hooks"]
>                 url = https://gerrit.googlesource.com/plugins/hooks
>                 gitdirname = plugins%2fhooks
>
> and use that for lookups instead of regenerating the directory name.
> What do you think?

As I just looked at worktree code, this sounds intriguing for the wrong
reason (again), as a user may want to point the gitdirname to a repository
that they have already on disk outside the actual superproject. They
would be reinventing worktrees in the submodule space. ;-)

This would open up the security hole that we just had, again.
So we'd have to make sure that the gitdirname (instead of the
now meaningless subsection name) is proof to ../ attacks.

I feel uneasy about this as then the user might come in
and move submodules and repoint the gitdirname...
to a not url encoded path. Exposing this knob just
asks for trouble, no?

On the other hand, the only requirement for the "name" is
now uniqueness, and that is implied with subsections,
so I guess it looks elegant.

What would happen if gitdirname is changed as part of
history? (The same problem we have now with changing
the subsection name)

The more I think about it the less appealing this is, but it looks
elegant.

Stefan

  reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-07 23:06 [RFC] " Brandon Williams
2018-08-07 23:25 ` Jonathan Nieder
2018-08-08  0:14 ` Junio C Hamano
2018-08-08 22:33 ` [PATCH 0/2] munge submodule names Brandon Williams
2018-08-08 22:33   ` [PATCH 1/2] submodule: create helper to build paths to submodule gitdirs Brandon Williams
2018-08-08 23:21     ` Stefan Beller
2018-08-09  0:45       ` Brandon Williams
2018-08-10 21:27     ` Junio C Hamano
2018-08-10 21:45       ` Brandon Williams
2018-08-08 22:33   ` [PATCH 2/2] submodule: munge paths to submodule git directories Brandon Williams
2018-08-09 21:26     ` Jeff King
2018-08-14 18:04       ` Brandon Williams
2018-08-14 18:57         ` Jonathan Nieder
2018-08-14 21:08           ` Stefan Beller [this message]
2018-08-14 21:12             ` Jonathan Nieder
2018-08-14 22:34               ` Stefan Beller
2018-08-16  2:34                 ` Jonathan Nieder
2018-08-16  2:39                   ` Stefan Beller
2018-08-16  2:47                     ` Jonathan Nieder
2018-08-16 17:34                       ` Brandon Williams
2018-08-16 18:19                       ` [PATCH] submodule: add config for where gitdirs are located Brandon Williams
2018-08-20 22:03                         ` Junio C Hamano
2018-08-16 15:07                   ` [PATCH 2/2] submodule: munge paths to submodule git directories Junio C Hamano
2018-08-14 18:58         ` Jeff King
2018-08-28 21:35         ` Stefan Beller
2018-08-29  5:25           ` Jeff King
2018-08-29 18:10             ` Stefan Beller
2018-08-29 21:03               ` Jeff King
2018-08-29 21:10                 ` Stefan Beller
2018-08-29 21:18                   ` Jonathan Nieder
2018-08-29 21:27                     ` Stefan Beller
2018-08-29 21:30                   ` Jeff King
2018-08-29 21:09             ` Jonathan Nieder
2018-08-29 21:14               ` Stefan Beller
2018-08-29 21:25                 ` Brandon Williams
2018-08-29 21:32               ` Jeff King
2018-08-16  0:19     ` Aaron Schrab
2019-01-15  1:25 ` [RFC] " Jonathan Nieder
2019-01-17 17:32   ` Jeff King
2019-01-17 17:57     ` Stefan Beller

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