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From: Jonathan Nieder <jrnieder@gmail.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 6/7] verify_path(): disallow symlinks in .gitattributes and .gitignore
Date: Mon, 5 Oct 2020 01:09:30 -0700	[thread overview]
Message-ID: <20201005080930.GI1166820@google.com> (raw)
In-Reply-To: <20201005072406.GF2291074@coredump.intra.peff.net>

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.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> I note that neither these new tests nor the existing .gitmodules ones
> confirm that we catch the obscured ntfs/hfs forms in the actual code
> paths (instead, we feed them to a synthetic test-tool helper in t0060).
> I think that's OK, but if we wanted to be super-paranoid we could beef
> up these tests with trickier names.

I think being exhaustive wouldn't be worth it, but perhaps *one*
example (e.g., ".gitmodules ") would not be a terrible idea.

>  read-cache.c              | 12 +++++++++---
>  t/t7450-bad-meta-files.sh | 29 +++++++++++++++++++++++++++++
>  2 files changed, 38 insertions(+), 3 deletions(-)

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>

[...]
> --- a/t/t7450-bad-meta-files.sh
> +++ b/t/t7450-bad-meta-files.sh
> @@ -267,4 +267,33 @@ test_expect_success 'git dirs of sibling submodules must not be nested' '
>  	test_i18ngrep "is inside git dir" err
>  '
>  
> +test_expect_success 'create repo with symlinked .gitattributes file' '
> +	git init symlink-attr &&
> +	target=$(echo target | git -C symlink-attr hash-object -w --stdin) &&
> +	tree=$(
> +		printf "120000 blob $target\t.gitattributes\n" |
> +		git -C symlink-attr mktree
> +	)
> +'
> +
> +test_expect_success 'refuse to load symlinked .gitattributes into index' '
> +	test_must_fail git -C symlink-attr read-tree $tree 2>err &&
> +	test_i18ngrep "invalid path.*gitattributes" err

This tests that it fails but doesn't test that it had no effect.
Would that be straightforward to check as well (e.g. an "ls-files -s"
before and after)?

  reply	other threads:[~2020-10-05  8:09 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-05  7:17 [PATCH 0/7] forbidding symlinked " 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 [this message]
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
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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