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When creating a directory on Windows whose path ends in a space or a
period (or chains thereof), the Win32 API "helpfully" trims those. For
example, `mkdir("abc ");` will return success, but actually create a
directory called `abc` instead.
This stems back to the DOS days, when all file names had exactly 8
characters plus exactly 3 characters for the file extension, and the
only way to have shorter names was by padding with spaces.
Sadly, this "helpful" behavior is a bit inconsistent: after a successful
`mkdir("abc ");`, a `mkdir("abc /def")` will actually _fail_ (because
the directory `abc ` does not actually exist).
Even if it would work, we now have a serious problem because a Git
repository could contain directories `abc` and `abc `, and on Windows,
they would be "merged" unintentionally.
As these paths are illegal on Windows, anyway, let's disallow any
accesses to such paths on that Operating System.
For practical reasons, this behavior is still guarded by the
config setting `core.protectNTFS`: it is possible (and at least two
regression tests make use of it) to create commits without involving the
worktree. In such a scenario, it is of course possible -- even on
Windows -- to create such file names.
Among other consequences, this patch disallows submodules' paths to end
in spaces on Windows (which would formerly have confused Git enough to
try to write into incorrect paths, anyway).
While this patch does not fix a vulnerability on its own, it prevents an
attack vector that was exploited in demonstrations of a number of
recently-fixed security bugs.
The regression test added to `t/t7417-submodule-path-url.sh` reflects
that attack vector.
Note that we have to adjust the test case "prevent git~1 squatting on
Windows" in `t/t7415-submodule-names.sh` because of a very subtle issue.
It tries to clone two submodules whose names differ only in a trailing
period character, and as a consequence their git directories differ in
the same way. Previously, when Git tried to clone the second submodule,
it thought that the git directory already existed (because on Windows,
when you create a directory with the name `b.` it actually creates `b`),
but with this patch, the first submodule's clone will fail because of
the illegal name of the git directory. Therefore, when cloning the
second submodule, Git will take a different code path: a fresh clone
(without an existing git directory). Both code paths fail to clone the
second submodule, both because the the corresponding worktree directory
exists and is not empty, but the error messages are worded differently.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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We recently banned submodule urls that look like
command-line options. This is the matching change to ban
leading-dash paths.
As with the urls, this should not break any use cases that
currently work. Even with our "--" separator passed to
git-clone, git-submodule.sh gets confused. Without the code
portion of this patch, the clone of "-sub" added in t7417
would yield results like:
/path/to/git-submodule: 410: cd: Illegal option -s
/path/to/git-submodule: 417: cd: Illegal option -s
/path/to/git-submodule: 410: cd: Illegal option -s
/path/to/git-submodule: 417: cd: Illegal option -s
Fetched in submodule path '-sub', but it did not contain b56243f8f4eb91b2f1f8109452e659f14dd3fbe4. Direct fetching of that commit failed.
Moreover, naively adding such a submodule doesn't work:
$ git submodule add $url -sub
The following path is ignored by one of your .gitignore files:
-sub
even though there is no such ignore pattern (the test script
hacks around this with a well-placed "git mv").
Unlike leading-dash urls, though, it's possible that such a
path _could_ be useful if we eventually made it work. So
this commit should be seen not as recommending a particular
policy, but rather temporarily closing off a broken and
possibly dangerous code-path. We may revisit this decision
later.
There are two minor differences to the tests in t7416 (that
covered urls):
1. We don't have a "./-sub" escape hatch to make this
work, since the submodule code expects to be able to
match canonical index names to the path field (so you
are free to add submodule config with that path, but we
would never actually use it, since an index entry would
never start with "./").
2. After this patch, cloning actually succeeds. Since we
ignore the submodule.*.path value, we fail to find a
config stanza for our submodule at all, and simply
treat it as inactive. We still check for the "ignoring"
message.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Johannes Schindelin
Jeff King