The `--export-marks` option of `git fast-import` is exposed also via the
in-stream command `feature export-marks=...` and it allows overwriting
arbitrary paths.
This topic branch prevents the in-stream version, to prevent arbitrary
file accesses by `git fast-import` streams coming from untrusted sources
(e.g. in remote helpers that are based on `git fast-import`).
This fixes CVE-2019-1348.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Previously, this function was completely undocumented. It is worth,
though, to explain what is going on, as it is not really obvious at all.
Suggested-by: Garima Singh <garima.singh@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The backslash character is not a valid part of a file name on Windows.
Hence it is dangerous to allow writing files that were unpacked from
tree objects, when the stored file name contains a backslash character:
it will be misinterpreted as directory separator.
This not only causes ambiguity when a tree contains a blob `a\b` and a
tree `a` that contains a blob `b`, but it also can be used as part of an
attack vector to side-step the careful protections against writing into
the `.git/` directory during a clone of a maliciously-crafted
repository.
Let's prevent that, addressing CVE-2019-1354.
Note: we guard against backslash characters in tree objects' file names
_only_ on Windows (because on other platforms, even on those where NTFS
volumes can be mounted, the backslash character is _not_ a directory
separator), and _only_ when `core.protectNTFS = true` (because users
might need to generate tree objects for other platforms, of course
without touching the worktree, e.g. using `git update-index
--cacheinfo`).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
In addition to preventing `.git` from being tracked by Git, on Windows
we also have to prevent `git~1` from being tracked, as the default NTFS
short name (also known as the "8.3 filename") for the file name `.git`
is `git~1`, otherwise it would be possible for malicious repositories to
write directly into the `.git/` directory, e.g. a `post-checkout` hook
that would then be executed _during_ a recursive clone.
When we implemented appropriate protections in 2b4c6efc82 (read-cache:
optionally disallow NTFS .git variants, 2014-12-16), we had analyzed
carefully that the `.git` directory or file would be guaranteed to be
the first directory entry to be written. Otherwise it would be possible
e.g. for a file named `..git` to be assigned the short name `git~1` and
subsequently, the short name generated for `.git` would be `git~2`. Or
`git~3`. Or even `~9999999` (for a detailed explanation of the lengths
we have to go to protect `.gitmodules`, see the commit message of
e7cb0b4455 (is_ntfs_dotgit: match other .git files, 2018-05-11)).
However, by exploiting two issues (that will be addressed in a related
patch series close by), it is currently possible to clone a submodule
into a non-empty directory:
- On Windows, file names cannot end in a space or a period (for
historical reasons: the period separating the base name from the file
extension was not actually written to disk, and the base name/file
extension was space-padded to the full 8/3 characters, respectively).
Helpfully, when creating a directory under the name, say, `sub.`, that
trailing period is trimmed automatically and the actual name on disk
is `sub`.
This means that while Git thinks that the submodule names `sub` and
`sub.` are different, they both access `.git/modules/sub/`.
- While the backslash character is a valid file name character on Linux,
it is not so on Windows. As Git tries to be cross-platform, it
therefore allows backslash characters in the file names stored in tree
objects.
Which means that it is totally possible that a submodule `c` sits next
to a file `c\..git`, and on Windows, during recursive clone a file
called `..git` will be written into `c/`, of course _before_ the
submodule is cloned.
Note that the actual exploit is not quite as simple as having a
submodule `c` next to a file `c\..git`, as we have to make sure that the
directory `.git/modules/b` already exists when the submodule is checked
out, otherwise a different code path is taken in `module_clone()` that
does _not_ allow a non-empty submodule directory to exist already.
Even if we will address both issues nearby (the next commit will
disallow backslash characters in tree entries' file names on Windows,
and another patch will disallow creating directories/files with trailing
spaces or periods), it is a wise idea to defend in depth against this
sort of attack vector: when submodules are cloned recursively, we now
_require_ the directory to be empty, addressing CVE-2019-1349.
Note: the code path we patch is shared with the code path of `git
submodule update --init`, which must not expect, in general, that the
directory is empty. Hence we have to introduce the new option
`--force-init` and hand it all the way down from `git submodule` to the
actual `git submodule--helper` process that performs the initial clone.
Reported-by: Nicolas Joly <Nicolas.Joly@microsoft.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
As with export-marks in the previous commit, import-marks can access the
filesystem. This is significantly less dangerous than export-marks
because it only involves reading from arbitrary paths, rather than
writing them. However, it could still be surprising and have security
implications (e.g., exfiltrating data from a service that accepts
fast-import streams).
Let's lump it (and its "if-exists" counterpart) in with export-marks,
and enable the in-stream version only if --allow-unsafe-features is set.
Signed-off-by: Jeff King <peff@peff.net>
The fast-import stream command "feature export-marks=<path>" lets the
stream write marks to an arbitrary path. This may be surprising if you
are running fast-import against an untrusted input (which otherwise
cannot do anything except update Git objects and refs).
Let's disallow the use of this feature by default, and provide a
command-line option to re-enable it (you can always just use the
command-line --export-marks as well, but the in-stream version provides
an easy way for exporters to control the process).
This is a backwards-incompatible change, since the default is flipping
to the new, safer behavior. However, since the main users of the
in-stream versions would be import/export-based remote helpers, and
since we trust remote helpers already (which are already running
arbitrary code), we'll pass the new option by default when reading a
remote helper's stream. This should minimize the impact.
Note that the implementation isn't totally simple, as we have to work
around the fact that fast-import doesn't parse its command-line options
until after it has read any "feature" lines from the stream. This is how
it lets command-line options override in-stream. But in our case, it's
important to parse the new --allow-unsafe-features first.
There are three options for resolving this:
1. Do a separate "early" pass over the options. This is easy for us to
do because there are no command-line options that allow the
"unstuck" form (so there's no chance of us mistaking an argument
for an option), though it does introduce a risk of incorrect
parsing later (e.g,. if we convert to parse-options).
2. Move the option parsing phase back to the start of the program, but
teach the stream-reading code never to override an existing value.
This is tricky, because stream "feature" lines override each other
(meaning we'd have to start tracking the source for every option).
3. Accept that we might parse a "feature export-marks" line that is
forbidden, as long we don't _act_ on it until after we've parsed
the command line options.
This would, in fact, work with the current code, but only because
the previous patch fixed the export-marks parser to avoid touching
the filesystem.
So while it works, it does carry risk of somebody getting it wrong
in the future in a rather subtle and unsafe way.
I've gone with option (1) here as simple, safe, and unlikely to cause
regressions.
This fixes CVE-2019-1348.
Signed-off-by: Jeff King <peff@peff.net>
When we parse the --export-marks option, we don't immediately open the
file, but we do create any leading directories. This can be especially
confusing when a command-line option overrides an in-stream one, in
which case we'd create the leading directory for the in-stream file,
even though we never actually write the file.
Let's instead create the directories just before opening the file, which
means we'll create only useful directories. Note that this could change
the handling of relative paths if we chdir() in between, but we don't
actually do so; the only permanent chdir is from setup_git_directory()
which runs before either code path (potentially we should take the
pre-setup dir into account to avoid surprising the user, but that's an
orthogonal change).
The test just adapts the existing "override" test to use paths with
leading directories. This checks both that the correct directory is
created (which worked before but was not tested), and that the
overridden one is not (our new fix here).
While we're here, let's also check the error result of
safe_create_leading_directories(). We'd presumably notice any failure
immediately after when we try to open the file itself, but we can give a
more specific error message in this case.
Signed-off-by: Jeff King <peff@peff.net>
When asked to import marks from "subdir/file.marks", we create the
leading directory "subdir" if it doesn't exist. This makes no sense for
importing marks, where we only ever open the path for reading.
Most of the time this would be a noop, since if the marks file exists,
then the leading directories exist, too. But if it doesn't (e.g.,
because --import-marks-if-exists was used), then we'd create the useless
directory.
This dates back to 580d5f83e7 (fast-import: always create marks_file
directories, 2010-03-29). Even then it was useless, so it seems to have
been added in error alongside the --export-marks case (which _is_
helpful).
Signed-off-by: Jeff King <peff@peff.net>
We parse options like "--max-pack-size=" using skip_prefix(), which
makes sense to get at the bytes after the "=". However, we also parse
"--quiet" and "--stats" with skip_prefix(), which allows things like
"--quiet-nonsense" to behave like "--quiet".
This was a mistaken conversion in 0f6927c229 (fast-import: put option
parsing code in separate functions, 2009-12-04). Let's tighten this to
an exact match, which was the original intent.
Signed-off-by: Jeff King <peff@peff.net>
Our tests confirm that providing two "import-marks" options in a
fast-import stream is an error. However, the invoked command would fail
even without covering this case, because the marks files themselves do
not actually exist. Let's create the files to make sure we fail for the
right reason (we actually do, because the option parsing happens before
we open anything, but this future-proofs our test).
Signed-off-by: Jeff King <peff@peff.net>
A recent update accidentally squelched an error message when the
run_command API failed to run a missing command, which has been
corrected.
* jc/run-command-report-exec-failure-fix:
run-command: report exec failure
"git help -a" did not work well when an overly long alias is
defined, which has been corrected.
* js/help-commands-verbose-by-default-fix:
help -a: handle aliases with long names gracefully
help.h: fix coding style
The new test_oid machinery in the test library requires reading
some information from t/oid-info/hash-info and t/oid-info/oid.
The logic to read from these files in shell uses built-in "read"
command, which leaves CR at the end of these text files when they
are checked out with CRLF line endings, at least when run with bash
shipped with Git for Windows. This results in an unexpected value
in the variable these lines are read into, leading the tests to
fail.
Mark them to be checked out always with the LF line endings.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The oneline notwithstanding, 13374987dd (completion: use _gitcompbuiltin
for format-patch, 2018-11-03) changed also the way send-email options
are completed, by asking the git send-email command itself what options
it offers.
Necessarily, this must fail when built with NO_PERL because send-email
itself is a Perl script. Which means that we need the PERL prerequisite
for the send-email test case in t9902.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The test t4256-am-format-flowed.sh requires carefully applying a
patch after ignoring padding whitespace. This breaks if the file
is munged to include CRLF line endings instead of LF.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The compiler reports this because show_gitcomp() never actually
returns a value:
"parse-options.c", line 520: warning: Function has no return
statement : show_gitcomp
We could shut the compiler up. But instead let's not bury exit() too
deep. Do the same as internal -h handling, return a special error code
and handle the exit() in parse_options() (and other
parse_options_step() callers) instead.
Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We take pains to determine the longest command beforehand, so that we
can align the category column after printing the command names.
However, then we re-use that value when printing the aliases. If any
alias name is longer than the longest command name, we consequently try
to add a negative number of spaces (but `mput_char()` does not expect
any negative values and simply decrements until the value is 0, i.e.
it tries to add close to 2**31 spaces).
Let's fix this by adjusting the `longest` variable before printing the
aliases.
This fixes https://github.com/git-for-windows/git/issues/1975.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We want a space after the `while` keyword.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 321fd823 ("run-command: mark path lookup errors with ENOENT",
2018-10-24), we rewrote the logic to execute a command by looking
in the directories on $PATH; as a side effect, a request to run a
command that is not found on $PATH is noticed even before a child
process is forked to execute it.
We however stopped to report an exec failure in such a case by
mistake. Add a logic to report the error unless silent-exec-failure
is requested, to match the original code.
Reported-by: John Passaro <john.a.passaro@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The text body of section Behavioral Differences is typeset as code,
but should be regular text. Remove the indentation to achieve that.
While here, prettify the language:
- use "the x backend" instead of "x-based rebase";
- use present tense instead of future tense;
and use subsections instead of a list.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We have three double-quote characters, which is one too many or too few.
Dropping the last one seems to match the original intention best.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
I had to read this sentence a few times to understand it. Let's try to
clarify it.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some items that should be in "Performance, Internal Implementation,
Development Support etc." have ended up in "UI, Workflows & Features"
and "Fixes since v2.19". Move them, and do s/uses/use/ while at it.
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit d8981c3f88 ("format-patch: do not let its diff-options affect
--range-diff", 2018-11-30) taught `show_range_diff()` to accept a
NULL-pointer as an indication that it should use its own "reasonable
default". That fixed a regression from a5170794 ("Merge branch
'ab/range-diff-no-patch'", 2018-11-18), but unfortunately it introduced
a regression of its own.
In particular, it means we forget the `file` member of the diff options,
so rather than placing a range-diff in the cover-letter, we write it to
stdout. In order to fix this, rewrite the two callers adjusted by
d8981c3f88 to instead create a "dummy" set of diff options where they
only fill in the fields we absolutely require, such as output file and
color.
Modify and extend the existing tests to try and verify that the right
contents end up in the right place.
Don't revert `show_range_diff()`, i.e., let it keep accepting NULL.
Rather than removing what is dead code and figuring out it isn't
actually dead and we've broken 2.20, just leave it for now.
[es: retain diff coloring when going to stdout]
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin