As with the previous commit, we must call fsck's "finish"
function in order to catch any queued objects for
.gitmodules checks.
This second pass will be able to access any incoming
objects, because we will have exploded them to loose objects
by now.
This isn't quite ideal, because it means that bad objects
may have been written to the object database (and a
subsequent operation could then reference them, even if the
other side doesn't send the objects again). However, this is
sufficient when used with receive.fsckObjects, since those
loose objects will all be placed in a temporary quarantine
area that will get wiped if we find any problems.
Signed-off-by: Jeff King <peff@peff.net>
Now that the internal fsck code is capable of checking
.gitmodules files, we just need to teach its callers to use
the "finish" function to check any queued objects.
With this, we can now catch the malicious case in t7415 with
git-fsck.
Signed-off-by: Jeff King <peff@peff.net>
This patch detects and blocks submodule names which do not
match the policy set forth in submodule-config. These should
already be caught by the submodule code itself, but putting
the check here means that newer versions of Git can protect
older ones from malicious entries (e.g., a server with
receive.fsckObjects will block the objects, protecting
clients which fetch from it).
As a side effect, this means fsck will also complain about
.gitmodules files that cannot be parsed (or were larger than
core.bigFileThreshold).
Signed-off-by: Jeff King <peff@peff.net>
If we have a tree that points to a .gitmodules blob but
don't have that blob, we can't check its contents. This
produces an fsck error when we encounter it.
But in the case of a promisor object, this absence is
expected, and we must not complain. Note that this can
technically circumvent our transfer.fsckObjects check.
Imagine a client fetches a tree, but not the matching
.gitmodules blob. An fsck of the incoming objects will show
that we don't have enough information. Later, we do fetch
the actual blob. But we have no idea that it's a .gitmodules
file.
The only ways to get around this would be to re-scan all of
the existing trees whenever new ones enter (which is
expensive), or to somehow persist the gitmodules_found set
between fsck runs (which is complicated).
In practice, it's probably OK to ignore the problem. Any
repository which has all of the objects (including the one
serving the promisor packs) can perform the checks. Since
promisor packs are inherently about a hierarchical topology
in which clients rely on upstream repositories, those
upstream repositories can protect all of their downstream
clients from broken objects.
Signed-off-by: Jeff King <peff@peff.net>
In preparation for performing fsck checks on .gitmodules
files, this commit plumbs in the actual detection of the
files. Note that unlike most other fsck checks, this cannot
be a property of a single object: we must know that the
object is found at a ".gitmodules" path at the root tree of
a commit.
Since the fsck code only sees one object at a time, we have
to mark the related objects to fit the puzzle together. When
we see a commit we mark its tree as a root tree, and when
we see a root tree with a .gitmodules file, we mark the
corresponding blob to be checked.
In an ideal world, we'd check the objects in topological
order: commits followed by trees followed by blobs. In that
case we can avoid ever loading an object twice, since all
markings would be complete by the time we get to the marked
objects. And indeed, if we are checking a single packfile,
this is the order in which Git will generally write the
objects. But we can't count on that:
1. git-fsck may show us the objects in arbitrary order
(loose objects are fed in sha1 order, but we may also
have multiple packs, and we process each pack fully in
sequence).
2. The type ordering is just what git-pack-objects happens
to write now. The pack format does not require a
specific order, and it's possible that future versions
of Git (or a custom version trying to fool official
Git's fsck checks!) may order it differently.
3. We may not even be fscking all of the relevant objects
at once. Consider pushing with transfer.fsckObjects,
where one push adds a blob at path "foo", and then a
second push adds the same blob at path ".gitmodules".
The blob is not part of the second push at all, but we
need to mark and check it.
So in the general case, we need to make up to three passes
over the objects: once to make sure we've seen all commits,
then once to cover any trees we might have missed, and then
a final pass to cover any .gitmodules blobs we found in the
second pass.
We can simplify things a bit by loosening the requirement
that we find .gitmodules only at root trees. Technically
a file like "subdir/.gitmodules" is not parsed by Git, but
it's not unreasonable for us to declare that Git is aware of
all ".gitmodules" files and make them eligible for checking.
That lets us drop the root-tree requirement, which
eliminates one pass entirely. And it makes our worst case
much better: instead of potentially queueing every root tree
to be re-examined, the worst case is that we queue each
unique .gitmodules blob for a second look.
This patch just adds the boilerplate to find .gitmodules
files. The actual content checks will come in a subsequent
commit.
Signed-off-by: Jeff King <peff@peff.net>
Because fscking a blob has always been a noop, we didn't
bother passing around the blob data. In preparation for
content-level checks, let's fix up a few things:
1. The fsck_object() function just returns success for any
blob. Let's a noop fsck_blob(), which we can fill in
with actual logic later.
2. The fsck_loose() function in builtin/fsck.c
just threw away blob content after loading it. Let's
hold onto it until after we've called fsck_object().
The easiest way to do this is to just drop the
parse_loose_object() helper entirely. Incidentally,
this also fixes a memory leak: if we successfully
loaded the object data but did not parse it, we would
have left the function without freeing it.
3. When fsck_loose() loads the object data, it
does so with a custom read_loose_object() helper. This
function streams any blobs, regardless of size, under
the assumption that we're only checking the sha1.
Instead, let's actually load blobs smaller than
big_file_threshold, as the normal object-reading
code-paths would do. This lets us fsck small files, and
a NULL return is an indication that the blob was so big
that it needed to be streamed, and we can pass that
information along to fsck_blob().
Signed-off-by: Jeff King <peff@peff.net>
There's no need for us to manually check for ".git"; it's a
subset of the other filesystem-specific tests. Dropping it
makes our code slightly shorter. More importantly, the
existing code may make a reader wonder why ".GIT" is not
covered here, and whether that is a bug (it isn't, as it's
also covered in the filesystem-specific tests).
Signed-off-by: Jeff King <peff@peff.net>
If fsck reports an error, we say only "Error in object".
This isn't quite as bad as it might seem, since the fsck
code would have dumped some errors to stderr already. But it
might help to give a little more context. The earlier output
would not have even mentioned "fsck", and that may be a clue
that the "fsck.*" or "*.fsckObjects" config may be relevant.
Signed-off-by: Jeff King <peff@peff.net>
* jk/submodule-name-verify-fix:
verify_path: disallow symlinks in .gitmodules
update-index: stat updated files earlier
verify_path: drop clever fallthrough
skip_prefix: add icase-insensitive variant
is_{hfs,ntfs}_dotgitmodules: add tests
path: match NTFS short names for more .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
Note that this includes two bits of evil-merge:
- there's a new call to verify_path() that doesn't actually
have a mode available. It should be OK to pass "0" here,
since we're just manipulating the untracked cache, not an
actual index entry.
- the lstat() in builtin/update-index.c:update_one() needs
to be updated to handle the fsmonitor case (without this
it still behaves correctly, but does an unnecessary
lstat).
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>
Fix a regression in 88f6ffc1c2 ("add -p: only bind search key if
there's more than one hunk", 2018-02-13) which is present in
2.17.0-rc*, but not 2.16.0.
In Perl, regex variables like $1 always refer to the last regex
match. When the aforementioned change added a new regex match between
the old match and the corresponding code that was expecting $1, the $1
variable would always be undef, since the newly inserted regex match
doesn't have any captures.
As a result the "/" feature to search for a string in a hunk by regex
completely broke, on git.git:
$ perl -pi -e 's/Git/Tig/g' README.md
$ ./git --exec-path=$PWD add -p
[..]
Stage this hunk [y,n,q,a,d,j,J,g,/,s,e,?]? s
Split into 4 hunks.
[...]
Stage this hunk [y,n,q,a,d,j,J,g,/,s,e,?]? /Many
Use of uninitialized value $1 in string eq at /home/avar/g/git/git-add--interactive line 1568, <STDIN> line 1.
search for regex? Many
I.e. the initial "/regex" command wouldn't work, and would always emit
a warning and ask again for a regex, now it works as intended again.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When upload-pack gained partial clone support (v2.17.0-rc0~132^2~12,
2017-12-08), it was guarded by the uploadpack.allowFilter config item
to allow server operators to control when they start supporting it.
That config item didn't go far enough, though: it controls whether the
'filter' capability is advertised, but if a (custom) client ignores
the capability advertisement and passes a filter specification anyway,
the server would handle that despite allowFilter being false.
This is particularly significant if a security bug is discovered in
this new experimental partial clone code. Installations without
uploadpack.allowFilter ought not to be affected since they don't
intend to support partial clone, but they would be swept up into being
vulnerable.
Simplify and limit the attack surface by making uploadpack.allowFilter
disable the feature, not just the advertisement of it.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Hotfix for recently graduated topic that give help to completion
scripts from the Git subcommands that are being completed
* nd/parseopt-completion:
t9902: disable test on the list of merge-strategies under GETTEXT_POISON
completion: clear cached --options when sourcing the completion script
This fixes a regression introduced in 2e612731b5 (submodule: port
submodule subcommand 'deinit' from shell to C, 2018-01-15), when
handling pathspecs that do not exist gracefully. This restores the
historic behavior of reporting the pathspec as unknown and returning
instead of reporting a bug.
Reported-by: Peter Oberndorfer <kumbayo84@arcor.de>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 1ada5020b3 ("stash: use stash_push for no verb form", 2017-02-28),
when the pathspec argument was introduced in 'git stash', that was also
documented. However I forgot to remove an extra square bracket after
the '--message' argument, even though the square bracket should have
been after the pathspec argument (where it was also added).
Remove the extra square bracket after the '--message' argument, to show
that the pathspec argument should be used with the 'push' verb.
While the pathspec argument can be used without the push verb, that's a
special case described later in the man page, and removing the first extra
square bracket instead of the second one makes the synopis easier to
understand.
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code to learn the list of merge strategies from the output of
"git merge -s help" forces C locale, so that it can notice the
message shown to indicate where the list starts in the output.
However, GETTEXT_POISON build corrupts its output even when run in
the C locale, and we cannot expect this test to succeed.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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
Jeff King