When an attacker can convince a user to clone a crafted repository
that contains an embedded bare repository with malicious hooks, any Git
command the user runs after entering that subdirectory will discover
the bare repository and execute the hooks. The user does not even need
to run a Git command explicitly: many shell prompts run `git status`
in the background to display branch and dirty state information, and
`git status` in turn may invoke the fsmonitor hook if so configured,
making the user vulnerable the moment they `cd` into the directory. The
`safe.bareRepository` configuration variable (introduced in 8959555cee
(setup_git_directory(): add an owner check for the top-level directory,
2022-03-02)) already provides protection against this attack vector by
allowing users to set it to "explicit", but the default remained "all"
for backwards compatibility.
Since Git 3.0 is the natural point to change defaults to safer
values, flip the default from "all" to "explicit" when built with
`WITH_BREAKING_CHANGES`. This means Git will refuse to work with bare
repositories that are discovered implicitly by walking up the directory
tree. Bare repositories specified via `--git-dir` or `GIT_DIR` continue
to work, and directories that look like `.git`, worktrees, or submodule
directories are unaffected (the existing `is_implicit_bare_repo()`
whitelist handles those cases).
Users who rely on implicit bare repository discovery can restore the
previous behavior by setting `safe.bareRepository=all` in their global
or system configuration.
The test for the "safe.bareRepository in the repository" scenario
needed a more involved fix: it writes a `safe.bareRepository=all`
entry into the bare repository's own config to verify that repo-local
config does not override the protected (global) setting. Previously,
`test_config -C` was used to write that entry, but its cleanup runs `git
-C <bare-repo> config --unset`, which itself fails when the default is
"explicit" and the global config has already been cleaned up. Switching
to direct git config --file access avoids going through repository
discovery entirely.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.adoc
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission and Documentation/CodingGuidelines).
Those wishing to help with error message, usage and informational message
string translations (localization l10) should see po/README.md
(a po file is a Portable Object file that holds the translations).
To subscribe to the list, send an email to git+subscribe@vger.kernel.org (see https://subspace.kernel.org/subscribing.html for details). The mailing list archives are available at https://lore.kernel.org/git/, https://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks