Re: [RFC] submodule: munge paths to submodule git directories

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Jan 15, 2019, 01:25 UTC
Message-ID: <20190115012507.GK162110@google.com>
In-Reply-To: <20180807230637.247200-1-bmwill@google.com>

Hi,

In August, 2018, Brandon Williams wrote:

Show 8 quoted lines

> Commit 0383bbb901 (submodule-config: verify submodule names as paths,
> 2018-04-30) introduced some checks to ensure that submodule names don't
> include directory traversal components (e.g. "../").
>
> This addresses the vulnerability identified in 0383bbb901 but the root
> cause is that we use submodule names to construct paths to the
> submodule's git directory.  What we really should do is munge the
> submodule name before using it to construct a path.

Thanks again for this. I liked the proposal enough to run Git with patches implementing it for a while. That said, there were some unaddressed comments in the review.

I've put a summary in https://crbug.com/git/28 to make this easier to pick up where we left off. Summary from there of the upstream review:

1. Using urlencoding to escape the slashes is fine, but what if we
   want to escape some other character (for example to handle
   case-insensitive filesystems)?

   Proposal: Store the escaping mapping in config[1] so it can be
   modified it in the future:

	[submodule "plugin/hooks"]
		gitdirname = plugins%2fhooks

2. The urlencoded name could conflict with a submodule that has % in
   its name in an existing clone created by an older version of Git.

   Proposal: Put submodules in a new .git/submodules/ directory
   instead of .git/modules/.

3. These gitdirname settings can clutter up .git/config.

   Proposal: For the "easy" cases (e.g. submodule name consisting of
   [a-z]*), allow omitting the gitdirname setting.

Is that a fair summary? Are there concerns from the review that I forgot, or would a new version of the series that addresses those three problems put us in good shape?

Thanks, Jonathan

[1] https://public-inbox.org/git/20180816181940.46114-1-bmwill@google.com/