* maint-2.15:
Git 2.15.3
Git 2.14.5
submodule-config: ban submodule paths that start with a dash
submodule-config: ban submodule urls that start with dash
submodule--helper: use "--" to signal end of clone options
* maint-2.14:
Git 2.14.5
submodule-config: ban submodule paths that start with a dash
submodule-config: ban submodule urls that start with dash
submodule--helper: use "--" to signal end of clone options
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>
The previous commit taught the submodule code to invoke our
"git clone $url $path" with a "--" separator so that we
aren't confused by urls or paths that start with dashes.
However, that's just one code path. It's not clear if there
are others, and it would be an easy mistake to add one in
the future. Moreover, even with the fix in the previous
commit, it's quite hard to actually do anything useful with
such an entry. Any url starting with a dash must fall into
one of three categories:
- it's meant as a file url, like "-path". But then any
clone is not going to have the matching path, since it's
by definition relative inside the newly created clone. If
you spell it as "./-path", the submodule code sees the
"/" and translates this to an absolute path, so it at
least works (assuming the receiver has the same
filesystem layout as you). But that trick does not apply
for a bare "-path".
- it's meant as an ssh url, like "-host:path". But this
already doesn't work, as we explicitly disallow ssh
hostnames that begin with a dash (to avoid option
injection against ssh).
- it's a remote-helper scheme, like "-scheme::data". This
_could_ work if the receiver bends over backwards and
creates a funny-named helper like "git-remote--scheme".
But normally there would not be any helper that matches.
Since such a url does not work today and is not likely to do
anything useful in the future, let's simply disallow them
entirely. That protects the existing "git clone" path (in a
belt-and-suspenders way), along with any others that might
exist.
Our tests cover two cases:
1. A file url with "./" continues to work, showing that
there's an escape hatch for people with truly silly
repo names.
2. A url starting with "-" is rejected.
Note that we expect case (2) to fail, but it would have done
so even without this commit, for the reasons given above.
So instead of just expecting failure, let's also check for
the magic word "ignoring" on stderr. That lets us know that
we failed for the right reason.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we clone a submodule, we call "git clone $url $path".
But there's nothing to say that those components can't begin
with a dash themselves, confusing git-clone into thinking
they're options. Let's pass "--" to make it clear what we
expect.
There's no test here, because it's actually quite hard to
make these names work, even with "git clone" parsing them
correctly. And we're going to restrict these cases even
further in future commits. So we'll leave off testing until
then; this is just the minimal fix to prevent us from doing
something stupid with a badly formed entry.
Reported-by: joernchen <joernchen@phenoelit.de>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* maint-2.15:
Git 2.15.2
Git 2.14.4
Git 2.13.7
verify_path: disallow symlinks in .gitmodules
update-index: stat updated files earlier
verify_dotfile: mention case-insensitivity in comment
verify_path: drop clever fallthrough
skip_prefix: add case-insensitive variant
is_{hfs,ntfs}_dotgitmodules: add tests
is_ntfs_dotgit: match other .git files
is_hfs_dotgit: match other .git files
is_ntfs_dotgit: use a size_t for traversing string
submodule-config: verify submodule names as paths
* maint-2.14:
Git 2.14.4
Git 2.13.7
verify_path: disallow symlinks in .gitmodules
update-index: stat updated files earlier
verify_dotfile: mention case-insensitivity in comment
verify_path: drop clever fallthrough
skip_prefix: add case-insensitive variant
is_{hfs,ntfs}_dotgitmodules: add tests
is_ntfs_dotgit: match other .git files
is_hfs_dotgit: match other .git files
is_ntfs_dotgit: use a size_t for traversing string
submodule-config: verify submodule names as paths
* maint-2.13:
Git 2.13.7
verify_path: disallow symlinks in .gitmodules
update-index: stat updated files earlier
verify_dotfile: mention case-insensitivity in comment
verify_path: drop clever fallthrough
skip_prefix: add case-insensitive variant
is_{hfs,ntfs}_dotgitmodules: add tests
is_ntfs_dotgit: match other .git files
is_hfs_dotgit: match other .git files
is_ntfs_dotgit: use a size_t for traversing string
submodule-config: verify submodule names as paths
* jk/submodule-fix-loose:
verify_path: disallow symlinks in .gitmodules
update-index: stat updated files earlier
verify_dotfile: mention case-insensitivity in comment
verify_path: drop clever fallthrough
skip_prefix: add case-insensitive variant
is_{hfs,ntfs}_dotgitmodules: add tests
is_ntfs_dotgit: match other .git files
is_hfs_dotgit: match other .git files
is_ntfs_dotgit: use a size_t for traversing string
submodule-config: verify submodule names as paths
There are a few reasons it's not a good idea to make
.gitmodules a symlink, including:
1. It won't be portable to systems without symlinks.
2. It may behave inconsistently, since Git may look at
this file in the index or a tree without bothering to
resolve any symbolic links. We don't do this _yet_, but
the config infrastructure is there and it's planned for
the future.
With some clever code, we could make (2) work. And some
people may not care about (1) if they only work on one
platform. But there are a few security reasons to simply
disallow it:
a. A symlinked .gitmodules file may circumvent any fsck
checks of the content.
b. Git may read and write from the on-disk file without
sanity checking the symlink target. So for example, if
you link ".gitmodules" to "../oops" and run "git
submodule add", we'll write to the file "oops" outside
the repository.
Again, both of those are problems that _could_ be solved
with sufficient code, but given the complications in (1) and
(2), we're better off just outlawing it explicitly.
Note the slightly tricky call to verify_path() in
update-index's update_one(). There we may not have a mode if
we're not updating from the filesystem (e.g., we might just
be removing the file). Passing "0" as the mode there works
fine; since it's not a symlink, we'll just skip the extra
checks.
Signed-off-by: Jeff King <peff@peff.net>
In the update_one(), we check verify_path() on the proposed
path before doing anything else. In preparation for having
verify_path() look at the file mode, let's stat the file
earlier, so we can check the mode accurately.
This is made a bit trickier by the fact that this function
only does an lstat in a few code paths (the ones that flow
down through process_path()). So we can speculatively do the
lstat() here and pass the results down, and just use a dummy
mode for cases where we won't actually be updating the index
from the filesystem.
Signed-off-by: Jeff King <peff@peff.net>
We're more restrictive than we need to be in matching ".GIT"
on case-sensitive filesystems; let's make a note that this
is intentional.
Signed-off-by: Jeff King <peff@peff.net>
We check ".git" and ".." in the same switch statement, and
fall through the cases to share the end-of-component check.
While this saves us a line or two, it makes modifying the
function much harder. Let's just write it out.
Signed-off-by: Jeff King <peff@peff.net>
We have the convenient skip_prefix() helper, but if you want
to do case-insensitive matching, you're stuck doing it by
hand. We could add an extra parameter to the function to
let callers ask for this, but the function is small and
somewhat performance-critical. Let's just re-implement it
for the case-insensitive version.
Signed-off-by: Jeff King <peff@peff.net>
This tests primarily for NTFS issues, but also adds one example of an
HFS+ issue.
Thanks go to Congyi Wu for coming up with the list of examples where
NTFS would possibly equate the filename with `.gitmodules`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Jeff King <peff@peff.net>
When we started to catch NTFS short names that clash with .git, we only
looked for GIT~1. This is sufficient because we only ever clone into an
empty directory, so .git is guaranteed to be the first subdirectory or
file in that directory.
However, even with a fresh clone, .gitmodules is *not* necessarily the
first file to be written that would want the NTFS short name GITMOD~1: a
malicious repository can add .gitmodul0000 and friends, which sorts
before `.gitmodules` and is therefore checked out *first*. For that
reason, we have to test not only for ~1 short names, but for others,
too.
It's hard to just adapt the existing checks in is_ntfs_dotgit(): since
Windows 2000 (i.e., in all Windows versions still supported by Git),
NTFS short names are only generated in the <prefix>~<number> form up to
number 4. After that, a *different* prefix is used, calculated from the
long file name using an undocumented, but stable algorithm.
For example, the short name of .gitmodules would be GITMOD~1, but if it
is taken, and all of ~2, ~3 and ~4 are taken, too, the short name
GI7EBA~1 will be used. From there, collisions are handled by
incrementing the number, shortening the prefix as needed (until ~9999999
is reached, in which case NTFS will not allow the file to be created).
We'd also want to handle .gitignore and .gitattributes, which suffer
from a similar problem, using the fall-back short names GI250A~1 and
GI7D29~1, respectively.
To accommodate for that, we could reimplement the hashing algorithm, but
it is just safer and simpler to provide the known prefixes. This
algorithm has been reverse-engineered and described at
https://usn.pw/blog/gen/2015/06/09/filenames/, which is defunct but
still available via https://web.archive.org/.
These can be recomputed by running the following Perl script:
-- snip --
use warnings;
use strict;
sub compute_short_name_hash ($) {
my $checksum = 0;
foreach (split('', $_[0])) {
$checksum = ($checksum * 0x25 + ord($_)) & 0xffff;
}
$checksum = ($checksum * 314159269) & 0xffffffff;
$checksum = 1 + (~$checksum & 0x7fffffff) if ($checksum & 0x80000000);
$checksum -= (($checksum * 1152921497) >> 60) * 1000000007;
return scalar reverse sprintf("%x", $checksum & 0xffff);
}
print compute_short_name_hash($ARGV[0]);
-- snap --
E.g., running that with the argument ".gitignore" will
result in "250a" (which then becomes "gi250a" in the code).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Jeff King <peff@peff.net>
Both verify_path() and fsck match ".git", ".GIT", and other
variants specific to HFS+. Let's allow matching other
special files like ".gitmodules", which we'll later use to
enforce extra restrictions via verify_path() and fsck.
Signed-off-by: Jeff King <peff@peff.net>
We walk through the "name" string using an int, which can
wrap to a negative value and cause us to read random memory
before our array (e.g., by creating a tree with a name >2GB,
since "int" is still 32 bits even on most 64-bit platforms).
Worse, this is easy to trigger during the fsck_tree() check,
which is supposed to be protecting us from malicious
garbage.
Note one bit of trickiness in the existing code: we
sometimes assign -1 to "len" at the end of the loop, and
then rely on the "len++" in the for-loop's increment to take
it back to 0. This is still legal with a size_t, since
assigning -1 will turn into SIZE_MAX, which then wraps
around to 0 on increment.
Signed-off-by: Jeff King <peff@peff.net>
Submodule "names" come from the untrusted .gitmodules file,
but we blindly append them to $GIT_DIR/modules to create our
on-disk repo paths. This means you can do bad things by
putting "../" into the name (among other things).
Let's sanity-check these names to avoid building a path that
can be exploited. There are two main decisions:
1. What should the allowed syntax be?
It's tempting to reuse verify_path(), since submodule
names typically come from in-repo paths. But there are
two reasons not to:
a. It's technically more strict than what we need, as
we really care only about breaking out of the
$GIT_DIR/modules/ hierarchy. E.g., having a
submodule named "foo/.git" isn't actually
dangerous, and it's possible that somebody has
manually given such a funny name.
b. Since we'll eventually use this checking logic in
fsck to prevent downstream repositories, it should
be consistent across platforms. Because
verify_path() relies on is_dir_sep(), it wouldn't
block "foo\..\bar" on a non-Windows machine.
2. Where should we enforce it? These days most of the
.gitmodules reads go through submodule-config.c, so
I've put it there in the reading step. That should
cover all of the C code.
We also construct the name for "git submodule add"
inside the git-submodule.sh script. This is probably
not a big deal for security since the name is coming
from the user anyway, but it would be polite to remind
them if the name they pick is invalid (and we need to
expose the name-checker to the shell anyway for our
test scripts).
This patch issues a warning when reading .gitmodules
and just ignores the related config entry completely.
This will generally end up producing a sensible error,
as it works the same as a .gitmodules file which is
missing a submodule entry (so "submodule update" will
barf, but "git clone --recurse-submodules" will print
an error but not abort the clone.
There is one minor oddity, which is that we print the
warning once per malformed config key (since that's how
the config subsystem gives us the entries). So in the
new test, for example, the user would see three
warnings. That's OK, since the intent is that this case
should never come up outside of malicious repositories
(and then it might even benefit the user to see the
message multiple times).
Credit for finding this vulnerability and the proof of
concept from which the test script was adapted goes to
Etienne Stalmans.
Signed-off-by: Jeff King <peff@peff.net>
Hotfix for a recent topic.
* tg/worktree-create-tracking:
git-worktree.txt: fix indentation of example and text of 'add' command
git-worktree.txt: fix missing ")" typo
Code clean-up.
* nd/shared-index-fix:
read-cache: don't write index twice if we can't write shared index
read-cache.c: move tempfile creation/cleanup out of write_shared_index
read-cache.c: change type of "temp" in write_shared_index()
Doc updates.
* ks/submodule-doc-updates:
Doc/git-submodule: improve readability and grammar of a sentence
Doc/gitsubmodules: make some changes to improve readability and syntax
