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| author | Glen Choo <chooglen@google.com> | 2022-07-14 21:28:01 +0000 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2022-07-14 15:08:29 -0700 |
| commit | 8d1a7448206e11cdea657c35b04cc49db39be933 (patch) | |
| tree | adb883132f48ef4f809f7ed2fd4b633850998ee9 /Documentation/config | |
| parent | 6061601d9f1f1c95da5f9304c319218f7cc3ec75 (diff) | |
| download | git-8d1a7448206e11cdea657c35b04cc49db39be933.tar.gz | |
setup.c: create `safe.bareRepository`
There is a known social engineering attack that takes advantage of the
fact that a working tree can include an entire bare repository,
including a config file. A user could run a Git command inside the bare
repository thinking that the config file of the 'outer' repository would
be used, but in reality, the bare repository's config file (which is
attacker-controlled) is used, which may result in arbitrary code
execution. See [1] for a fuller description and deeper discussion.
A simple mitigation is to forbid bare repositories unless specified via
`--git-dir` or `GIT_DIR`. In environments that don't use bare
repositories, this would be minimally disruptive.
Create a config variable, `safe.bareRepository`, that tells Git whether
or not to die() when working with a bare repository. This config is an
enum of:
- "all": allow all bare repositories (this is the default)
- "explicit": only allow bare repositories specified via --git-dir
or GIT_DIR.
If we want to protect users from such attacks by default, neither value
will suffice - "all" provides no protection, but "explicit" is
impractical for bare repository users. A more usable default would be to
allow only non-embedded bare repositories ([2] contains one such
proposal), but detecting if a repository is embedded is potentially
non-trivial, so this work is not implemented in this series.
[1]: https://lore.kernel.org/git/kl6lsfqpygsj.fsf@chooglen-macbookpro.roam.corp.google.com
[2]: https://lore.kernel.org/git/5b969c5e-e802-c447-ad25-6acc0b784582@github.com
Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation/config')
| -rw-r--r-- | Documentation/config/safe.txt | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/config/safe.txt b/Documentation/config/safe.txt index f72b440879..bde7f31459 100644 --- a/Documentation/config/safe.txt +++ b/Documentation/config/safe.txt @@ -1,3 +1,22 @@ +safe.bareRepository:: + Specifies which bare repositories Git will work with. The currently + supported values are: ++ +* `all`: Git works with all bare repositories. This is the default. +* `explicit`: Git only works with bare repositories specified via + the top-level `--git-dir` command-line option, or the `GIT_DIR` + environment variable (see linkgit:git[1]). ++ +If you do not use bare repositories in your workflow, then it may be +beneficial to set `safe.bareRepository` to `explicit` in your global +config. This will protect you from attacks that involve cloning a +repository that contains a bare repository and running a Git command +within that directory. ++ +This config setting is only respected in protected configuration (see +<<SCOPES>>). This prevents the untrusted repository from tampering with +this value. + safe.directory:: These config entries specify Git-tracked directories that are considered safe even if they are owned by someone other than the |