Sergey Organov noticed and reported "--patch --no-patch --raw"
behaves differently from just "--raw". It turns out that there are
a few interesting bugs in the implementation and documentation.
* First, the documentation for "--no-patch" was unclear that it
could be read to mean "--no-patch" countermands an earlier
"--patch" but not other things. The intention of "--no-patch"
ever since it was introduced at d09cd15d (diff: allow --no-patch
as synonym for -s, 2013-07-16) was to serve as a synonym for
"-s", so "--raw --patch --no-patch" should have produced no
output, but it can be (mis)read to allow showing only "--raw"
output.
* Then the interaction between "-s" and other format options were
poorly implemented. Modern versions of Git uses one bit each to
represent formatting options like "--patch", "--stat" in a single
output_format word, but for historical reasons, "-s" also is
represented as another bit in the same word. This allows two
interesting bugs to happen, and we have both X-<.
(1) After setting a format bit, then setting NO_OUTPUT with "-s",
the code to process another "--<format>" option drops the
NO_OUTPUT bit to allow output to be shown again. However,
the code to handle "-s" only set NO_OUTPUT without unsetting
format bits set earlier, so the earlier format bit got
revealed upon seeing the second "--<format>" option. This is
the problem Sergey observed.
(2) After setting NO_OUTPUT with "-s", code to process
"--<format>" option can forget to unset NO_OUTPUT, leaving
the command still silent.
It is tempting to change the meaning of "--no-patch" to mean
"disable only the patch format output" and reimplement "-s" as "not
showing anything", but it would be an end-user visible change in
behavior. Let's fix the interactions of these bits to first make
"-s" work as intended.
The fix is conceptually very simple.
* Whenever we set DIFF_FORMAT_FOO because we saw the "--foo"
option (e.g. DIFF_FORMAT_RAW is set when the "--raw" option is
given), we make sure we drop DIFF_FORMAT_NO_OUTPUT. We forgot to
do so in some of the options and caused (2) above.
* When processing "-s" option, we should not just set
DIFF_FORMAT_NO_OUTPUT bit, but clear other DIFF_FORMAT_* bits.
We didn't do so and retained format bits set by options
previously seen, causing (1) above.
It is even more tempting to lose NO_OUTPUT bit and instead take
output_format word being 0 as its replacement, but that would break
the mechanism "git show" uses to default to "--patch" output, where
the distinction between telling the command to be silent with "-s"
and having no output format specified on the command line matters,
and an explicit output format given on the command line should not
be "combined" with the default "--patch" format.
So, while we cannot lose the NO_OUTPUT bit, as a follow-up work, we
may want to replace it with OPTION_GIVEN bit, and
* make "--patch", "--raw", etc. set DIFF_FORMAT_$format bit and
DIFF_FORMAT_OPTION_GIVEN bit on for each format. "--no-raw",
etc. will set off DIFF_FORMAT_$format bit but still record the
fact that we saw an option from the command line by setting
DIFF_FORMAT_OPTION_GIVEN bit.
* make "-s" (and its synonym "--no-patch") clear all other bits
and set only the DIFF_FORMAT_OPTION_GIVEN bit on.
which I suspect would make the code much cleaner without breaking
any end-user expectations.
Once that is in place, transitioning "--no-patch" to mean the
counterpart of "--patch", just like "--no-raw" only defeats an
earlier "--raw", would be quite simple at the code level. The
social cost of migrating the end-user expectations might be too
great for it to be worth, but at least the "GIVEN" bit clean-up
alone may be worth it.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The array of dirstat_file contained in the dirstat_dir structure is
not freed after the processing ends. Unfortunately, the member that
points at the array, .files, is incremented as the gather_dirstat()
function recursively walks it, and this needs to be plugged by
remembering the beginning of the array before gather_dirstat() mucks
with it and freeing it after we are done.
We can mark t4047 as leak-free. t4000, which is marked as
leak-free, now can exercise dirstat in it, which will happen next.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* maint-2.37: (31 commits)
Git 2.37.7
Git 2.36.6
Git 2.35.8
Git 2.34.8
Git 2.33.8
Git 2.32.7
Git 2.31.8
tests: avoid using `test_i18ncmp`
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
...
* maint-2.36: (30 commits)
Git 2.36.6
Git 2.35.8
Git 2.34.8
Git 2.33.8
Git 2.32.7
Git 2.31.8
tests: avoid using `test_i18ncmp`
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
t0033: GETTEXT_POISON fix
...
* maint-2.35: (29 commits)
Git 2.35.8
Git 2.34.8
Git 2.33.8
Git 2.32.7
Git 2.31.8
tests: avoid using `test_i18ncmp`
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
t0033: GETTEXT_POISON fix
http: support CURLOPT_PROTOCOLS_STR
...
* maint-2.34: (28 commits)
Git 2.34.8
Git 2.33.8
Git 2.32.7
Git 2.31.8
tests: avoid using `test_i18ncmp`
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
t0033: GETTEXT_POISON fix
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
...
* maint-2.33: (27 commits)
Git 2.33.8
Git 2.32.7
Git 2.31.8
tests: avoid using `test_i18ncmp`
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
t0033: GETTEXT_POISON fix
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
http-push: prefer CURLOPT_UPLOAD to CURLOPT_PUT
...
* maint-2.32: (26 commits)
Git 2.32.7
Git 2.31.8
tests: avoid using `test_i18ncmp`
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
t0033: GETTEXT_POISON fix
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
http-push: prefer CURLOPT_UPLOAD to CURLOPT_PUT
ci: install python on ubuntu
...
* maint-2.31: (25 commits)
Git 2.31.8
tests: avoid using `test_i18ncmp`
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
t0033: GETTEXT_POISON fix
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
http-push: prefer CURLOPT_UPLOAD to CURLOPT_PUT
ci: install python on ubuntu
ci: use the same version of p4 on both Linux and macOS
...
Since `test_i18ncmp` was deprecated in v2.31.*, the instances added in
v2.30.9 needed to be converted to `test_cmp` calls.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
* maint-2.30: (23 commits)
Git 2.30.9
gettext: avoid using gettext if the locale dir is not present
apply --reject: overwrite existing `.rej` symlink if it exists
http.c: clear the 'finished' member once we are done with it
clone.c: avoid "exceeds maximum object size" error with GCC v12.x
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
t5604: GETTEXT_POISON fix, conclusion
t5604: GETTEXT_POISON fix, part 1
t5619: GETTEXT_POISON fix
t0003: GETTEXT_POISON fix, conclusion
t0003: GETTEXT_POISON fix, part 1
t0033: GETTEXT_POISON fix
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
http-push: prefer CURLOPT_UPLOAD to CURLOPT_PUT
ci: install python on ubuntu
ci: use the same version of p4 on both Linux and macOS
ci: remove the pipe after "p4 -V" to catch errors
github-actions: run gcc-8 on ubuntu-20.04 image
...
Avoids issues with renaming or deleting sections with long lines, where
configuration values may be interpreted as sections, leading to
configuration injection. Addresses CVE-2023-29007.
* tb/config-copy-or-rename-in-file-injection:
config.c: disallow overly-long lines in `copy_or_rename_section_in_file()`
config.c: avoid integer truncation in `copy_or_rename_section_in_file()`
config: avoid fixed-sized buffer when renaming/deleting a section
t1300: demonstrate failure when renaming sections with long lines
Signed-off-by: Taylor Blau <me@ttaylorr.com>
As a defense-in-depth measure to guard against any potentially-unknown
buffer overflows in `copy_or_rename_section_in_file()`, refuse to work
with overly-long lines in a gitconfig.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
When renaming (or deleting) a section of configuration, Git uses the
function `git_config_copy_or_rename_section_in_file()` to rewrite the
configuration file after applying the rename or deletion to the given
section.
To do this, Git repeatedly calls `fgets()` to read the existing
configuration data into a fixed size buffer.
When the configuration value under `old_name` exceeds the size of the
buffer, we will call `fgets()` an additional time even if there is no
newline in the configuration file, since our read length is capped at
`sizeof(buf)`.
If the first character of the buffer (after zero or more characters
satisfying `isspace()`) is a '[', Git will incorrectly treat it as
beginning a new section when the original section is being removed. In
other words, a configuration value satisfying this criteria can
incorrectly be considered as a new secftion instead of a variable in the
original section.
Avoid this issue by using a variable-width buffer in the form of a
strbuf rather than a fixed-with region on the stack. A couple of small
points worth noting:
- Using a strbuf will cause us to allocate arbitrary sizes to match
the length of each line. In practice, we don't expect any
reasonable configuration files to have lines that long, and a
bandaid will be introduced in a later patch to ensure that this is
the case.
- We are using strbuf_getwholeline() here instead of strbuf_getline()
in order to match `fgets()`'s behavior of leaving the trailing LF
character on the buffer (as well as a trailing NUL).
This could be changed later, but using strbuf_getwholeline() changes
the least about this function's implementation, so it is picked as
the safest path.
- It is temping to want to replace the loop to skip over characters
matching isspace() at the beginning of the buffer with a convenience
function like `strbuf_ltrim()`. But this is the wrong approach for a
couple of reasons:
First, it involves a potentially large and expensive `memmove()`
which we would like to avoid. Second, and more importantly, we also
*do* want to preserve those spaces to avoid changing the output of
other sections.
In all, this patch is a minimal replacement of the fixed-width buffer in
`git_config_copy_or_rename_section_in_file()` to instead use a `struct
strbuf`.
Reported-by: André Baptista <andre@ethiack.com>
Reported-by: Vítor Pinho <vitor@ethiack.com>
Helped-by: Patrick Steinhardt <ps@pks.im>
Co-authored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
When renaming a configuration section which has an entry whose length
exceeds the size of our buffer in config.c's implementation of
`git_config_copy_or_rename_section_in_file()`, Git will incorrectly
form a new configuration section with part of the data in the section
being removed.
In this instance, our first configuration file looks something like:
[b]
c = d <spaces> [a] e = f
[a]
g = h
Here, we have two configuration values, "b.c", and "a.g". The value "[a]
e = f" belongs to the configuration value "b.c", and does not form its
own section.
However, when renaming the section 'a' to 'xyz', Git will write back
"[xyz]\ne = f", but "[xyz]" is still attached to the value of "b.c",
which is why "e = f" on its own line becomes a new entry called "b.e".
A slightly different example embeds the section being renamed within
another section.
Demonstrate this failure in a test in t1300, which we will fix in the
following commit.
Co-authored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
The `git apply --reject` is expected to write out `.rej` files in case
one or more hunks fail to apply cleanly. Historically, the command
overwrites any existing `.rej` files. The idea being that
apply/reject/edit cycles are relatively common, and the generated `.rej`
files are not considered precious.
But the command does not overwrite existing `.rej` symbolic links, and
instead follows them. This is unsafe because the same patch could
potentially create such a symbolic link and point at arbitrary paths
outside the current worktree, and `git apply` would write the contents
of the `.rej` file into that location.
Therefore, let's make sure that any existing `.rej` file or symbolic
link is removed before writing it.
Reported-by: RyotaK <ryotak.mail@gmail.com>
Helped-by: Taylor Blau <me@ttaylorr.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In fade728df1 (apply: fix writing behind newly created symbolic links,
2023-02-02), we backported a patch onto v2.30.* that was originally
based on a much newer version. The v2.30.* release train still has the
GETTEXT_POISON CI job, though, and hence needs `test_i18n*` in its
tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In bffc762f87 (dir-iterator: prevent top-level symlinks without
FOLLOW_SYMLINKS, 2023-01-24), we backported a patch onto v2.30.* that
was originally based on a much newer version. The v2.30.* release train
still has the GETTEXT_POISON CI job, though, and hence needs
`test_i18n*` in its tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In cf8f6ce02a (clone: delay picking a transport until after
get_repo_path(), 2023-01-24), we backported a patch onto v2.30.* that
was originally based on a much newer version. The v2.30.* release train
still has the GETTEXT_POISON CI job, though, and hence needs
`test_i18n*` in its tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In 3c50032ff5 (attr: ignore overly large gitattributes files,
2022-12-01), we backported a patch onto v2.30.* that was originally
based on a much newer version. The v2.30.* release train still has the
GETTEXT_POISON CI job, though, and hence needs `test_i18n*` in its
tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In dfa6b32b5e (attr: ignore attribute lines exceeding 2048 bytes,
2022-12-01), we backported a patch onto v2.30.* that was originally
based on a much newer version. The v2.30.* release train still has the
GETTEXT_POISON CI job, though, and hence needs `test_i18n*` in its
tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In e47363e5a8 (t0033: add tests for safe.directory, 2022-04-13), we
backported a patch onto v2.30.* that was originally based on a much
newer version. The v2.30.* release train still has the GETTEXT_POISON
CI job, though, and hence needs `test_i18n*` in its tests.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
* maint-2.35:
Git 2.35.7
Git 2.34.7
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
http-push: prefer CURLOPT_UPLOAD to CURLOPT_PUT
Git 2.33.7
Git 2.32.6
Git 2.31.7
Git 2.30.8
apply: fix writing behind newly created symbolic links
dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS
clone: delay picking a transport until after get_repo_path()
t5619: demonstrate clone_local() with ambiguous transport
* maint-2.34:
Git 2.34.7
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
http-push: prefer CURLOPT_UPLOAD to CURLOPT_PUT
Git 2.33.7
Git 2.32.6
Git 2.31.7
Git 2.30.8
apply: fix writing behind newly created symbolic links
dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS
clone: delay picking a transport until after get_repo_path()
t5619: demonstrate clone_local() with ambiguous transport
* maint-2.33:
Git 2.33.7
Git 2.32.6
Git 2.31.7
Git 2.30.8
apply: fix writing behind newly created symbolic links
dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS
clone: delay picking a transport until after get_repo_path()
t5619: demonstrate clone_local() with ambiguous transport
* maint-2.32:
Git 2.32.6
Git 2.31.7
Git 2.30.8
apply: fix writing behind newly created symbolic links
dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS
clone: delay picking a transport until after get_repo_path()
t5619: demonstrate clone_local() with ambiguous transport
* maint-2.31:
Git 2.31.7
Git 2.30.8
apply: fix writing behind newly created symbolic links
dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS
clone: delay picking a transport until after get_repo_path()
t5619: demonstrate clone_local() with ambiguous transport
* maint-2.30:
Git 2.30.8
apply: fix writing behind newly created symbolic links
dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS
clone: delay picking a transport until after get_repo_path()
t5619: demonstrate clone_local() with ambiguous transport
Fix a vulnerability (CVE-2023-23946) that allows crafted input to trick
`git apply` into writing files outside of the working tree.
* ps/apply-beyond-symlink:
dir-iterator: prevent top-level symlinks without FOLLOW_SYMLINKS
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
When writing files git-apply(1) initially makes sure that none of the
files it is about to create are behind a symlink:
```
$ git init repo
Initialized empty Git repository in /tmp/repo/.git/
$ cd repo/
$ ln -s dir symlink
$ git apply - <<EOF
diff --git a/symlink/file b/symlink/file
new file mode 100644
index 0000000..e69de29
EOF
error: affected file 'symlink/file' is beyond a symbolic link
```
This safety mechanism is crucial to ensure that we don't write outside
of the repository's working directory. It can be fooled though when the
patch that is being applied creates the symbolic link in the first
place, which can lead to writing files in arbitrary locations.
Fix this by checking whether the path we're about to create is
beyond a symlink or not. Tightening these checks like this should be
fine as we already have these precautions in Git as explained
above. Ideally, we should update the check we do up-front before
starting to reflect the computed changes to the working tree so that
we catch this case as well, but as part of embargoed security work,
adding an equivalent check just before we try to write out a file
should serve us well as a reasonable first step.
Digging back into history shows that this vulnerability has existed
since at least Git v2.9.0. As Git v2.8.0 and older don't build on my
system anymore I cannot tell whether older versions are affected, as
well.
Reported-by: Joern Schneeweisz <jschneeweisz@gitlab.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When using the dir_iterator API, we first stat(2) the base path, and
then use that as a starting point to enumerate the directory's contents.
If the directory contains symbolic links, we will immediately die() upon
encountering them without the `FOLLOW_SYMLINKS` flag. The same is not
true when resolving the top-level directory, though.
As explained in a previous commit, this oversight in 6f054f9fb3
(builtin/clone.c: disallow `--local` clones with symlinks, 2022-07-28)
can be used as an attack vector to include arbitrary files on a victim's
filesystem from outside of the repository.
Prevent resolving top-level symlinks unless the FOLLOW_SYMLINKS flag is
given, which will cause clones of a repository with a symlink'd
"$GIT_DIR/objects" directory to fail.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the previous commit, t5619 demonstrates an issue where two calls to
`get_repo_path()` could trick Git into using its local clone mechanism
in conjunction with a non-local transport.
That sequence is:
- the starting state is that the local path https:/example.com/foo is a
symlink that points to ../../../.git/modules/foo. So it's dangling.
- get_repo_path() sees that no such path exists (because it's
dangling), and thus we do not canonicalize it into an absolute path
- because we're using --separate-git-dir, we create .git/modules/foo.
Now our symlink is no longer dangling!
- we pass the url to transport_get(), which sees it as an https URL.
- we call get_repo_path() again, on the url. This second call was
introduced by f38aa83f9a (use local cloning if insteadOf makes a
local URL, 2014-07-17). The idea is that we want to pull the url
fresh from the remote.c API, because it will apply any aliases.
And of course now it sees that there is a local file, which is a
mismatch with the transport we already selected.
The issue in the above sequence is calling `transport_get()` before
deciding whether or not the repository is indeed local, and not passing
in an absolute path if it is local.
This is reminiscent of a similar bug report in [1], where it was
suggested to perform the `insteadOf` lookup earlier. Taking that
approach may not be as straightforward, since the intent is to store the
original URL in the config, but to actually fetch from the insteadOf
one, so conflating the two early on is a non-starter.
Note: we pass the path returned by `get_repo_path(remote->url[0])`,
which should be the same as `repo_name` (aside from any `insteadOf`
rewrites).
We *could* pass `absolute_pathdup()` of the same argument, which
86521acaca (Bring local clone's origin URL in line with that of a remote
clone, 2008-09-01) indicates may differ depending on the presence of
".git/" for a non-bare repo. That matters for forming relative submodule
paths, but doesn't matter for the second call, since we're just feeding
it to the transport code, which is fine either way.
[1]: https://lore.kernel.org/git/CAMoD=Bi41mB3QRn3JdZL-FGHs4w3C2jGpnJB-CqSndO7FMtfzA@mail.gmail.com/
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When cloning a repository, Git must determine (a) what transport
mechanism to use, and (b) whether or not the clone is local.
Since f38aa83f9a (use local cloning if insteadOf makes a local URL,
2014-07-17), the latter check happens after the remote has been
initialized, and references the remote's URL instead of the local path.
This is done to make it possible for a `url.<base>.insteadOf` rule to
convert a remote URL into a local one, in which case the `clone_local()`
mechanism should be used.
However, with a specially crafted repository, Git can be tricked into
using a non-local transport while still setting `is_local` to "1" and
using the `clone_local()` optimization. The below test case
demonstrates such an instance, and shows that it can be used to include
arbitrary (known) paths in the working copy of a cloned repository on a
victim's machine[^1], even if local file clones are forbidden by
`protocol.file.allow`.
This happens in a few parts:
1. We first call `get_repo_path()` to see if the remote is a local
path. If it is, we replace the repo name with its absolute path.
2. We then call `transport_get()` on the repo name and decide how to
access it. If it was turned into an absolute path in the previous
step, then we should always treat it like a file.
3. We use `get_repo_path()` again, and set `is_local` as appropriate.
But it's already too late to rewrite the repo name as an absolute
path, since we've already fed it to the transport code.
The attack works by including a submodule whose URL corresponds to a
path on disk. In the below example, the repository "sub" is reachable
via the dumb HTTP protocol at (something like):
http://127.0.0.1:NNNN/dumb/sub.git
However, the path "http:/127.0.0.1:NNNN/dumb" (that is, a top-level
directory called "http:", then nested directories "127.0.0.1:NNNN", and
"dumb") exists within the repository, too.
To determine this, it first picks the appropriate transport, which is
dumb HTTP. It then uses the remote's URL in order to determine whether
the repository exists locally on disk. However, the malicious repository
also contains an embedded stub repository which is the target of a
symbolic link at the local path corresponding to the "sub" repository on
disk (i.e., there is a symbolic link at "http:/127.0.0.1/dumb/sub.git",
pointing to the stub repository via ".git/modules/sub/../../../repo").
This stub repository fools Git into thinking that a local repository
exists at that URL and thus can be cloned locally. The affected call is
in `get_repo_path()`, which in turn calls `get_repo_path_1()`, which
locates a valid repository at that target.
This then causes Git to set the `is_local` variable to "1", and in turn
instructs Git to clone the repository using its local clone optimization
via the `clone_local()` function.
The exploit comes into play because the stub repository's top-level
"$GIT_DIR/objects" directory is a symbolic link which can point to an
arbitrary path on the victim's machine. `clone_local()` resolves the
top-level "objects" directory through a `stat(2)` call, meaning that we
read through the symbolic link and copy or hardlink the directory
contents at the destination of the link.
In other words, we can get steps (1) and (3) to disagree by leveraging
the dangling symlink to pick a non-local transport in the first step,
and then set is_local to "1" in the third step when cloning with
`--separate-git-dir`, which makes the symlink non-dangling.
This can result in data-exfiltration on the victim's machine when
sensitive data is at a known path (e.g., "/home/$USER/.ssh").
The appropriate fix is two-fold:
- Resolve the transport later on (to avoid using the local
clone optimization with a non-local transport).
- Avoid reading through the top-level "objects" directory when
(correctly) using the clone_local() optimization.
This patch merely demonstrates the issue. The following two patches will
implement each part of the above fix, respectively.
[^1]: Provided that any target directory does not contain symbolic
links, in which case the changes from 6f054f9fb3 (builtin/clone.c:
disallow `--local` clones with symlinks, 2022-07-28) will abort the
clone.
Reported-by: yvvdwf <yvvdwf@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In b3b1a21d1a (sequencer: rewrite update-refs as user edits todo list,
2022-07-19), the 'todo_list_filter_update_refs()' step was added to handle
the removal of 'update-ref' lines from a 'rebase-todo'. Specifically, it
removes potential ref updates from the "update refs state" if a ref does not
have a corresponding 'update-ref' line.
However, because 'write_update_refs_state()' will not update the state if
the 'refs_to_oids' list was empty, removing *all* 'update-ref' lines will
result in the state remaining unchanged from how it was initialized (with
all refs' "after" OID being null). Then, when the ref update is applied, all
refs will be updated to null and consequently deleted.
To fix this, delete the 'update-refs' state file when 'refs_to_oids' is
empty. Additionally, add a tests covering "all update-ref lines removed"
cases.
Reported-by: herr.kaste <herr.kaste@gmail.com>
Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Helped-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Recently, a vulnerability was reported that can lead to an out-of-bounds
write when reading an unreasonably large gitattributes file. The root
cause of this error are multiple integer overflows in different parts of
the code when there are either too many lines, when paths are too long,
when attribute names are too long, or when there are too many attributes
declared for a pattern.
As all of these are related to size, it seems reasonable to restrict the
size of the gitattributes file via git-fsck(1). This allows us to both
stop distributing known-vulnerable objects via common hosting platforms
that have fsck enabled, and users to protect themselves by enabling the
`fetch.fsckObjects` config.
There are basically two checks:
1. We verify that size of the gitattributes file is smaller than
100MB.
2. We verify that the maximum line length does not exceed 2048
bytes.
With the preceding commits, both of these conditions would cause us to
either ignore the complete gitattributes file or blob in the first case,
or the specific line in the second case. Now with these consistency
checks added, we also grow the ability to stop distributing such files
in the first place when `receive.fsckObjects` is enabled.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Both the padding and wrapping formatting directives allow the caller to
specify an integer that ultimately leads to us adding this many chars to
the result buffer. As a consequence, it is trivial to e.g. allocate 2GB
of RAM via a single formatting directive and cause resource exhaustion
on the machine executing this logic. Furthermore, it is debatable
whether there are any sane usecases that require the user to pad data to
2GB boundaries or to indent wrapped data by 2GB.
Restrict the input sizes to 16 kilobytes at a maximum to limit the
amount of bytes that can be requested by the user. This is not meant
as a fix because there are ways to trivially amplify the amount of
data we generate via formatting directives; the real protection is
achieved by the changes in previous steps to catch and avoid integer
wraparound that causes us to under-allocate and access beyond the
end of allocated memory reagions. But having such a limit
significantly helps fuzzing the pretty format, because the fuzzer is
otherwise quite fast to run out-of-memory as it discovers these
formatters.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In `strbuf_utf8_replace()`, we call `utf8_width()` to compute the width
of the current glyph. If the glyph is a control character though it can
be that `utf8_width()` returns `-1`, but because we assign this value to
a `size_t` the conversion will cause us to underflow. This bug can
easily be triggered with the following command:
$ git log --pretty='format:xxx%<|(1,trunc)%x10'
>From all I can see though this seems to be a benign underflow that has
no security-related consequences.
Fix the bug by using an `int` instead. When we see a control character,
we now copy it into the target buffer but don't advance the current
width of the string.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
