Deprecate compat.is_<platform>, rewriting all uses by EliahKagan · Pull Request #1732 · gitpython-developers/GitPython

added 2 commits

November 4, 2023 15:54
Major changes:

- Add a comment in the git.compat module above the definitions of
  is_win, is_posix, and is_darwin stating that they are deprecated
  and recommending that os.name (or, where applicable,
  sys.platform) be used directly instead for clarity (and sometimes
  accuracy).

- Remove all uses of is_win and is_posix in git/ and test/,
  replacing them with `os.name == "nt"` and `os.name == "posix"`,
  respectively.

There were no uses of is_darwin to be replaced. Although it had
been used at one time, the last reference to it appears to have
been removed in 4545762 (gitpython-developers#1295).

This doesn't emit a DeprecationWarning when those attributes are
accessed in the git.compat module. (That might be valuable thing to
do in the future, if the git.compat module is to remain
non-deprecated overall.)

Two related less consequential changes are also included:

- Improve ordering and grouping of imports, in modules where they
  were already being changed as a result of no longer needing to
  import is_<platform> (usually is_win) from git.compat.

- Make minor revisions to a few comments, for readability. (This is
  in addition to somewhat more substantial revisions of comments
  where rewording was related to replacing uses of is_<platform>.)
This fixes compat.is_darwin to use sys.platform instead of os.name
so that it is True on macOS systems instead of always being False.
The deprecation rationale in compat.py is accordingly adjusted.

Together with c01fe76, this largely addresses gitpython-developers#1731.

EliahKagan added a commit to EliahKagan/GitPython that referenced this pull request

Dec 25, 2023
- Fix spacing in deprecation messages.
- Update versions in deprecation messages to reflect SemVer.
- Add and fix up docstrings for methods with some deprecated uses.
- Add a couple missing docstrings on nearby attributes and methods.
- Convert is_<platform> deprecation comment to three docstrings.
- Avoid wrongly claiming is_darwin still uses os.name (see gitpython-developers#1732).
- Convert some other comments to docstrings.
- Make disembodied """-strings docstrings or comments, per intent.
- Move some comments that were misplaced during auto-formatting.

This commit builds on the changes in 94a85d1 (gitpython-developers#1782).

lettuce-bot bot referenced this pull request in lettuce-financial/github-bot-signed-commit

Jan 10, 2024

renovate bot referenced this pull request in allenporter/flux-local

Jan 11, 2024

otc-zuul bot pushed a commit to opentelekomcloud-infra/eyes_on_docs that referenced this pull request

Mar 6, 2024

EliahKagan added a commit to EliahKagan/GitPython that referenced this pull request

Mar 7, 2024
On Windows, Python's subprocess module contains constants useful to
pass to the `creationflags` parameter of subprocess.Popen. These
are absent on other platforms, where they are not meaningful.

The code was already safe at runtime from any AttributeError
related to these constants, because they were only used in
git.cmd._safer_popen_windows, which was defined on Windows.

But in gitpython-developers#1792 I did not write the code in a way where mypy can
verify its correctness. So if a regression of the kind mypy can in
principle catch were to occur, it would be harder to notice it.

This refactors the code, keeping the same behavior but expressing
it in a way mypy can understand. This consists of two changes:

1. Only define _safer_popen_windows when the platform is Windows,
   placing it in the first branch of the `if` statement.

   This is needed because mypy will not take the only current call
   to that nonpublic function being on Windows as sufficient
   evidence that the platform is always Windows when it is run.

2. Determine the platform, for this purpose, using sys.platform
   instead of os.name.

   These are far from equivalent in general (see the deprecation
   rationale for is_<platform> in gitpython-developers#1732, revised in a0fa2bd
   in gitpython-developers#1787). However, in Python 3 (GitPython no longer supports
   Python 2), in the specific case of Windows, we have a choice of
   which to use, as both `sys.platform == "win32"` and
   `os.name == "nt"`.

   os.name is "nt" on native Windows, and "posix" on Cygwin.
   sys.platform is "win32" on native Windows (including 64-bit
   systems with 64-bit Python builds), and "cygwin" on Cygwin. See:
   https://docs.python.org/3/library/sys.html#sys.platform

   This is needed because the type stubs for the subprocess module
   use this sys.platform check (rather than an os.name check) to
   determine if the platform is Windows for the purpose of deciding
   which constants to say the subprocess module defines.

I have verified that neither of these changes is enough by itself.

JoeWang1127 referenced this pull request in googleapis/sdk-platform-java

Apr 6, 2024
[![Mend
Renovate](https://app.renovatebot.com/images/banner.svg)](https://renovatebot.com)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [GitPython](https://togithub.com/gitpython-developers/GitPython) |
`==3.1.40` -> `==3.1.41` |
[![age](https://developer.mend.io/api/mc/badges/age/pypi/GitPython/3.1.41?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/pypi/GitPython/3.1.41?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/pypi/GitPython/3.1.40/3.1.41?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/GitPython/3.1.40/3.1.41?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

> [!WARNING]
> Some dependencies could not be looked up. Check the Dependency
Dashboard for more information.

### GitHub Vulnerability Alerts

####
[CVE-2024-22190](https://togithub.com/gitpython-developers/GitPython/security/advisories/GHSA-2mqj-m65w-jghx)

### Summary

This issue exists because of an incomplete fix for CVE-2023-40590. On
Windows, GitPython uses an untrusted search path if it uses a shell to
run `git`, as well as when it runs `bash.exe` to interpret hooks. If
either of those features are used on Windows, a malicious `git.exe` or
`bash.exe` may be run from an untrusted repository.

### Details

Although GitPython often avoids executing programs found in an untrusted
search path since 3.1.33, two situations remain where this still occurs.
Either can allow arbitrary code execution under some circumstances.

#### When a shell is used

GitPython can be told to run `git` commands through a shell rather than
as direct subprocesses, by passing `shell=True` to any method that
accepts it, or by both setting `Git.USE_SHELL = True` and not passing
`shell=False`. Then the Windows `cmd.exe` shell process performs the
path search, and GitPython does not prevent that shell from finding and
running `git` in the current directory.

When GitPython runs `git` directly rather than through a shell, the
GitPython process performs the path search, and currently omits the
current directory by setting `NoDefaultCurrentDirectoryInExePath` in its
own environment during the `Popen` call. Although the `cmd.exe` shell
will honor this environment variable when present, GitPython does not
currently pass it into the shell subprocess's environment.

Furthermore, because GitPython sets the subprocess CWD to the root of a
repository's working tree, using a shell will run a malicious `git.exe`
in an untrusted repository even if GitPython itself is run from a
trusted location.

This also applies if `Git.execute` is called directly with `shell=True`
(or after `Git.USE_SHELL = True`) to run any command.

#### When hook scripts are run

On Windows, GitPython uses `bash.exe` to run hooks that appear to be
scripts. However, unlike when running `git`, no steps are taken to avoid
finding and running `bash.exe` in the current directory.

This allows the author of an untrusted fork or branch to cause a
malicious `bash.exe` to be run in some otherwise safe workflows. An
example of such a scenario is if the user installs a trusted hook while
on a trusted branch, then switches to an untrusted feature branch
(possibly from a fork) to review proposed changes. If the untrusted
feature branch contains a malicious `bash.exe` and the user's current
working directory is the working tree, and the user performs an action
that runs the hook, then although the hook itself is uncorrupted, it
runs with the malicious `bash.exe`.

Note that, while `bash.exe` is a shell, this is a separate scenario from
when `git` is run using the unrelated Windows `cmd.exe` shell.

### PoC

On Windows, create a `git.exe` file in a repository. Then create a
`Repo` object, and call any method through it (directly or indirectly)
that supports the `shell` keyword argument with `shell=True`:

```powershell
mkdir testrepo
git init testrepo
cp ... testrepo git.exe # Replace "..." with any executable of choice.
python -c "import git; print(git.Repo('testrepo').git.version(shell=True))"
```

The `git.exe` executable in the repository directory will be run.

Or use no `Repo` object, but do it from the location with the `git.exe`:

```powershell
cd testrepo
python -c "import git; print(git.Git().version(shell=True))"
```

The `git.exe` executable in the current directory will be run.

For the scenario with hooks, install a hook in a repository, create a
`bash.exe` file in the current directory, and perform an operation that
causes GitPython to attempt to run the hook:

```powershell
mkdir testrepo
cd testrepo
git init
mv .git/hooks/pre-commit.sample .git/hooks/pre-commit
cp ... bash.exe # Replace "..." with any executable of choice.
echo "Some text" >file.txt
git add file.txt
python -c "import git; git.Repo().index.commit('Some message')"
```

The `bash.exe` executable in the current directory will be run.

### Impact

The greatest impact is probably in applications that set `Git.USE_SHELL
= True` for historical reasons. (Undesired console windows had, in the
past, been created in some kinds of applications, when it was not used.)
Such an application may be vulnerable to arbitrary code execution from a
malicious repository, even with no other exacerbating conditions. This
is to say that, if a shell is used to run `git`, the full effect of
CVE-2023-40590 is still present. Furthermore, as noted above, running
the application itself from a trusted directory is not a sufficient
mitigation.

An application that does not direct GitPython to use a shell to run
`git` subprocesses thus avoids most of the risk. However, there is no
such straightforward way to prevent GitPython from running `bash.exe` to
interpret hooks. So while the conditions needed for that to be exploited
are more involved, it may be harder to mitigate decisively prior to
patching.

### Possible solutions

A straightforward approach would be to address each bug directly:

- When a shell is used, pass `NoDefaultCurrentDirectoryInExePath` into
the subprocess environment, because in that scenario the subprocess is
the `cmd.exe` shell that itself performs the path search.
- Set `NoDefaultCurrentDirectoryInExePath` in the GitPython process
environment during the `Popen` call made to run hooks with a `bash.exe`
subprocess.

These need only be done on Windows.

---

### Release Notes

<details>
<summary>gitpython-developers/GitPython (GitPython)</summary>

###
[`v3.1.41`](https://togithub.com/gitpython-developers/GitPython/releases/tag/3.1.41):
- fix Windows security issue

[Compare
Source](https://togithub.com/gitpython-developers/GitPython/compare/3.1.40...3.1.41)

The details about the Windows security issue [can be found in this
advisory](https://togithub.com/gitpython-developers/GitPython/security/advisories/GHSA-2mqj-m65w-jghx).

Special thanks go to
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) who reported the
issue and fixed it in a single stroke, while being responsible for an
incredible amount of improvements that he contributed over the last
couple of months ❤️.

#### What's Changed

- Add `__all__` in git.exc by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1719](https://togithub.com/gitpython-developers/GitPython/pull/1719)
- Set submodule update cadence to weekly by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1721](https://togithub.com/gitpython-developers/GitPython/pull/1721)
- Never modify sys.path by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1720](https://togithub.com/gitpython-developers/GitPython/pull/1720)
- Bump git/ext/gitdb from `8ec2390` to `ec58b7e` by
[@&#8203;dependabot](https://togithub.com/dependabot) in
[https://github.com/gitpython-developers/GitPython/pull/1722](https://togithub.com/gitpython-developers/GitPython/pull/1722)
- Revise comments, docstrings, some messages, and a bit of code by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1725](https://togithub.com/gitpython-developers/GitPython/pull/1725)
- Use zero-argument super() by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1726](https://togithub.com/gitpython-developers/GitPython/pull/1726)
- Remove obsolete note in \_iter_packed_refs by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1727](https://togithub.com/gitpython-developers/GitPython/pull/1727)
- Reorganize test_util and make xfail marks precise by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1729](https://togithub.com/gitpython-developers/GitPython/pull/1729)
- Clarify license and make module top comments more consistent by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1730](https://togithub.com/gitpython-developers/GitPython/pull/1730)
- Deprecate compat.is\_<platform>, rewriting all uses by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1732](https://togithub.com/gitpython-developers/GitPython/pull/1732)
- Revise and restore some module docstrings by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1735](https://togithub.com/gitpython-developers/GitPython/pull/1735)
- Make the rmtree callback Windows-only by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1739](https://togithub.com/gitpython-developers/GitPython/pull/1739)
- List all non-passing tests in test summaries by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1740](https://togithub.com/gitpython-developers/GitPython/pull/1740)
- Document some minor subtleties in test_util.py by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1749](https://togithub.com/gitpython-developers/GitPython/pull/1749)
- Always read metadata files as UTF-8 in setup.py by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1748](https://togithub.com/gitpython-developers/GitPython/pull/1748)
- Test native Windows on CI by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1745](https://togithub.com/gitpython-developers/GitPython/pull/1745)
- Test macOS on CI by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1752](https://togithub.com/gitpython-developers/GitPython/pull/1752)
- Let close_fds be True on all platforms by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1753](https://togithub.com/gitpython-developers/GitPython/pull/1753)
- Fix IndexFile.from_tree on Windows by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1751](https://togithub.com/gitpython-developers/GitPython/pull/1751)
- Remove unused TASKKILL fallback in AutoInterrupt by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1754](https://togithub.com/gitpython-developers/GitPython/pull/1754)
- Don't return with operand when conceptually void by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1755](https://togithub.com/gitpython-developers/GitPython/pull/1755)
- Group .gitignore entries by purpose by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1758](https://togithub.com/gitpython-developers/GitPython/pull/1758)
- Adding dubious ownership handling by
[@&#8203;marioaag](https://togithub.com/marioaag) in
[https://github.com/gitpython-developers/GitPython/pull/1746](https://togithub.com/gitpython-developers/GitPython/pull/1746)
- Avoid brittle assumptions about preexisting temporary files in tests
by [@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1759](https://togithub.com/gitpython-developers/GitPython/pull/1759)
- Overhaul noqa directives by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1760](https://togithub.com/gitpython-developers/GitPython/pull/1760)
- Clarify some Git.execute kill_after_timeout limitations by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1761](https://togithub.com/gitpython-developers/GitPython/pull/1761)
- Bump actions/setup-python from 4 to 5 by
[@&#8203;dependabot](https://togithub.com/dependabot) in
[https://github.com/gitpython-developers/GitPython/pull/1763](https://togithub.com/gitpython-developers/GitPython/pull/1763)
- Don't install black on Cygwin by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1766](https://togithub.com/gitpython-developers/GitPython/pull/1766)
- Extract all "import gc" to module level by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1765](https://togithub.com/gitpython-developers/GitPython/pull/1765)
- Extract remaining local "import gc" to module level by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1768](https://togithub.com/gitpython-developers/GitPython/pull/1768)
- Replace xfail with gc.collect in TestSubmodule.test_rename by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1767](https://togithub.com/gitpython-developers/GitPython/pull/1767)
- Enable CodeQL by [@&#8203;EliahKagan](https://togithub.com/EliahKagan)
in
[https://github.com/gitpython-developers/GitPython/pull/1769](https://togithub.com/gitpython-developers/GitPython/pull/1769)
- Replace some uses of the deprecated mktemp function by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1770](https://togithub.com/gitpython-developers/GitPython/pull/1770)
- Bump github/codeql-action from 2 to 3 by
[@&#8203;dependabot](https://togithub.com/dependabot) in
[https://github.com/gitpython-developers/GitPython/pull/1773](https://togithub.com/gitpython-developers/GitPython/pull/1773)
- Run some Windows environment variable tests only on Windows by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1774](https://togithub.com/gitpython-developers/GitPython/pull/1774)
- Fix TemporaryFileSwap regression where file_path could not be Path by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1776](https://togithub.com/gitpython-developers/GitPython/pull/1776)
- Improve hooks tests by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1777](https://togithub.com/gitpython-developers/GitPython/pull/1777)
- Fix if items of Index is of type PathLike by
[@&#8203;stegm](https://togithub.com/stegm) in
[https://github.com/gitpython-developers/GitPython/pull/1778](https://togithub.com/gitpython-developers/GitPython/pull/1778)
- Better document IterableObj.iter_items and improve some subclasses by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1780](https://togithub.com/gitpython-developers/GitPython/pull/1780)
- Revert "Don't install black on Cygwin" by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1783](https://togithub.com/gitpython-developers/GitPython/pull/1783)
- Add missing pip in $PATH on Cygwin CI by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1784](https://togithub.com/gitpython-developers/GitPython/pull/1784)
- Shorten Iterable docstrings and put IterableObj first by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1785](https://togithub.com/gitpython-developers/GitPython/pull/1785)
- Fix incompletely revised Iterable/IterableObj docstrings by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1786](https://togithub.com/gitpython-developers/GitPython/pull/1786)
- Pre-deprecate setting Git.USE_SHELL by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1782](https://togithub.com/gitpython-developers/GitPython/pull/1782)
- Deprecate Git.USE_SHELL by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1787](https://togithub.com/gitpython-developers/GitPython/pull/1787)
- In handle_process_output don't forward finalizer result by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1788](https://togithub.com/gitpython-developers/GitPython/pull/1788)
- Fix mypy warning "Missing return statement" by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1789](https://togithub.com/gitpython-developers/GitPython/pull/1789)
- Fix two remaining Windows untrusted search path cases by
[@&#8203;EliahKagan](https://togithub.com/EliahKagan) in
[https://github.com/gitpython-developers/GitPython/pull/1792](https://togithub.com/gitpython-developers/GitPython/pull/1792)

#### New Contributors

- [@&#8203;marioaag](https://togithub.com/marioaag) made their first
contribution in
[https://github.com/gitpython-developers/GitPython/pull/1746](https://togithub.com/gitpython-developers/GitPython/pull/1746)
- [@&#8203;stegm](https://togithub.com/stegm) made their first
contribution in
[https://github.com/gitpython-developers/GitPython/pull/1778](https://togithub.com/gitpython-developers/GitPython/pull/1778)

**Full Changelog**:
gitpython-developers/GitPython@3.1.40...3.1.41

</details>

---

### Configuration

📅 **Schedule**: Branch creation - "" (UTC), Automerge - At any time (no
schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you
are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the
rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update
again.

---

- [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check
this box

---

This PR has been generated by [Mend
Renovate](https://www.mend.io/free-developer-tools/renovate/). View
repository job log
[here](https://developer.mend.io/github/googleapis/sdk-platform-java).

<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNy4yNjkuMiIsInVwZGF0ZWRJblZlciI6IjM3LjI2OS4yIiwidGFyZ2V0QnJhbmNoIjoibWFpbiJ9-->