From: Jonathan Nieder <jrnieder@gmail.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v2 7/8] verify_path(): disallow symlinks in .gitattributes and .gitignore
Date: Mon, 26 Oct 2020 20:35:18 -0700 [thread overview]
Message-ID: <20201027033518.GH2645313@google.com> (raw)
In-Reply-To: <20201005121645.GG2907394@coredump.intra.peff.net>
Hi,
Jeff King wrote:
> However, it's still a reasonable idea to forbid symlinks for these
> files:
>
> - As noted, they can still be used to read out-of-repo files (which is
> fairly restricted, but in some circumstances you can probe file
> content by speculatively creating files and seeing if they get
> ignored)
>
> - They don't currently behave well in all cases. We sometimes read
> these files from the index, where we _don't_ follow symlinks (we'd
> just treat the symlink target as the .gitignore or .gitattributes
> content, which is actively wrong).
>
> This patch forbids symlinked versions of these files from entering the
> index. We already have helpers for obscured forms of the names from
> e7cb0b4455 (is_ntfs_dotgit: match other .git files, 2018-05-11) and
> 0fc333ba20 (is_hfs_dotgit: match other .git files, 2018-05-02), which
> were done as part of the series touching .gitmodules.
Thanks again for this. Since this patch has been in "next", we've
gotten a little experience of it at Google.
We've been running with the fsck check for a while (more than a year),
but not the verify_dotfile check. The verify_dotfile check didn't
trigger for anyone with .gitattributes, but it hit several people for
.gitignore. Some examples that users have mentioned:
Before https://android-review.googlesource.com/c/platform/tools/test/connectivity/+/1462771/
Android used a .gitignore symlink for two directories that had similar
gitignore requirements. Diagnosing the error was confusing for them,
especially because the "repo" wrapper tool produced messages like
error.GitError: Cannot initialize work tree for platform/tools/test/connectivity
Eventually someone manually ran
$ git add --a
error: invalid path 'acts_tests/.gitignore'
error: unable to add 'acts_tests/.gitignore' to index
fatal: adding files failed
which helped them realize it was a git issue and helped me point them
to the need to replace the symlink with a plain file.
As another example, a user working with the
https://github.com/bakerstu/openmrn.git repository noticed "git
checkout" commands failing. In this user's case, the checkout failed
part-way through, producing confusing behavior ("git status" showing
entries missing from the index). When I tried to reproduce this, I
wasn't able to clone the repository at all because it failed fsck;
after disabling transfer.fsckObjects, I still wasn't able to check out
HEAD.
Observations:
- since some widely used repositories have .gitignore symlinks, I
think we can't forbid it in fsck, alas
- it would be useful to be able to check whether these symlinks would
not escape the worktree, for a more targeted check. It might be
nice to even respect these settings when they would not escape the
worktree, but not necessarily
- we could use a clearer error message than "invalid path". There's
some room for improvement in "git checkout"'s error handling, too
--- I think my ideal would be if the operation would fail entirely,
with an advice message describing a checkout command that would
succeed (But how do I checkout another commit while excluding some
files? Should it suggest a sparse checkout?).
That's all I have time for today --- will revisit again tomorrow.
Thoughts?
Thanks,
Jonathan
next prev parent reply other threads:[~2020-10-27 3:35 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-05 7:17 [PATCH 0/7] forbidding symlinked .gitattributes and .gitignore Jeff King
2020-10-05 7:19 ` [PATCH 1/7] fsck_tree(): fix shadowed variable Jeff King
2020-10-05 7:44 ` Jonathan Nieder
2020-10-05 8:20 ` Jeff King
2020-10-05 8:29 ` Jonathan Nieder
2020-10-05 7:19 ` [PATCH 2/7] fsck_tree(): wrap some long lines Jeff King
2020-10-05 7:46 ` Jonathan Nieder
2020-10-05 7:19 ` [PATCH 3/7] t7415: rename to expand scope Jeff King
2020-10-05 7:50 ` Jonathan Nieder
2020-10-05 8:24 ` Jeff King
2020-10-05 8:34 ` Jonathan Nieder
2020-10-05 8:49 ` Jeff King
2020-10-05 7:20 ` [PATCH 4/7] t7450: test verify_path() handling of gitmodules Jeff King
2020-10-05 7:53 ` Jonathan Nieder
2020-10-05 8:30 ` Jeff King
2020-10-05 8:38 ` Jonathan Nieder
2020-10-05 7:21 ` [PATCH 5/7] t0060: test obscured .gitattributes and .gitignore matching Jeff King
2020-10-05 8:03 ` Jonathan Nieder
2020-10-05 8:40 ` Jeff King
2020-10-05 21:20 ` Johannes Schindelin
2020-10-06 14:01 ` Jeff King
2020-10-05 7:24 ` [PATCH 6/7] verify_path(): disallow symlinks in .gitattributes and .gitignore Jeff King
2020-10-05 8:09 ` Jonathan Nieder
2020-10-05 12:07 ` Jeff King
2020-10-05 7:25 ` [PATCH 7/7] fsck: complain when .gitattributes or .gitignore is a symlink Jeff King
2020-10-05 8:12 ` Jonathan Nieder
2020-10-05 8:53 ` Jeff King
2020-10-05 7:32 ` [PATCH 0/7] forbidding symlinked .gitattributes and .gitignore Jonathan Nieder
2020-10-05 8:58 ` Jeff King
2020-10-05 12:16 ` [PATCH v2 0/8] " Jeff King
2020-10-05 12:16 ` [PATCH v2 1/8] fsck_tree(): fix shadowed variable Jeff King
2020-10-05 12:16 ` [PATCH v2 2/8] fsck_tree(): wrap some long lines Jeff King
2020-10-05 12:16 ` [PATCH v2 3/8] t7415: rename to expand scope Jeff King
2020-10-05 12:16 ` [PATCH v2 4/8] t7450: test verify_path() handling of gitmodules Jeff King
2020-10-05 12:16 ` [PATCH v2 5/8] t7450: test .gitmodules symlink matching against obscured names Jeff King
2020-10-05 12:16 ` [PATCH v2 6/8] t0060: test obscured .gitattributes and .gitignore matching Jeff King
2020-10-05 12:16 ` [PATCH v2 7/8] verify_path(): disallow symlinks in .gitattributes and .gitignore Jeff King
2020-10-27 3:35 ` Jonathan Nieder [this message]
2020-10-27 7:58 ` Jeff King
2020-10-27 22:00 ` Junio C Hamano
2020-10-28 9:41 ` Jeff King
2020-10-27 23:43 ` Jonathan Nieder
2020-10-28 19:18 ` Junio C Hamano
2020-10-05 12:16 ` [PATCH v2 8/8] fsck: complain when .gitattributes or .gitignore is a symlink Jeff King
2020-10-06 20:41 ` [PATCH v2 0/8] forbidding symlinked .gitattributes and .gitignore Junio C Hamano
2020-10-20 23:19 ` Philip Oakley
2020-10-23 8:17 ` [PATCH] documentation symlink restrictions for .git* files Jeff King
2020-10-23 8:27 ` Jeff King
2020-10-26 22:18 ` Philip Oakley
2020-10-26 22:53 ` Jeff King
2020-10-26 23:32 ` Junio C Hamano
2020-10-27 7:26 ` Jeff King
2020-10-27 18:45 ` Junio C Hamano
2020-10-27 21:00 ` Philip Oakley
2020-10-28 19:14 ` Junio C Hamano
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