diff options
author | Carlo Marcelo Arenas Belón <carenas@gmail.com> | 2022-05-13 04:00:18 +0300 |
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committer | Junio C Hamano <gitster@pobox.com> | 2022-05-13 04:12:23 +0300 |
commit | ae9abbb63eea74441e3e8b153dc6ec1f94c373b4 (patch) | |
tree | 6c9397e6d261cd4c96e51d596a2afb75f03d5ea3 /Documentation | |
parent | 5f1a3fec8c304decaa9af2bf503712050a4a84e0 (diff) |
git-compat-util: avoid failing dir ownership checks if running privileged
bdc77d1d685 (Add a function to determine whether a path is owned by the
current user, 2022-03-02) checks for the effective uid of the running
process using geteuid() but didn't account for cases where that user was
root (because git was invoked through sudo or a compatible tool) and the
original uid that repository trusted for its config was no longer known,
therefore failing the following otherwise safe call:
guy@renard ~/Software/uncrustify $ sudo git describe --always --dirty
[sudo] password for guy:
fatal: unsafe repository ('/home/guy/Software/uncrustify' is owned by someone else)
Attempt to detect those cases by using the environment variables that
those tools create to keep track of the original user id, and do the
ownership check using that instead.
This assumes the environment the user is running on after going
privileged can't be tampered with, and also adds code to restrict that
the new behavior only applies if running as root, therefore keeping the
most common case, which runs unprivileged, from changing, but because of
that, it will miss cases where sudo (or an equivalent) was used to change
to another unprivileged user or where the equivalent tool used to raise
privileges didn't track the original id in a sudo compatible way.
Because of compatibility with sudo, the code assumes that uid_t is an
unsigned integer type (which is not required by the standard) but is used
that way in their codebase to generate SUDO_UID. In systems where uid_t
is signed, sudo might be also patched to NOT be unsigned and that might
be able to trigger an edge case and a bug (as described in the code), but
it is considered unlikely to happen and even if it does, the code would
just mostly fail safely, so there was no attempt either to detect it or
prevent it by the code, which is something that might change in the future,
based on expected user feedback.
Reported-by: Guy Maurel <guy.j@maurel.de>
Helped-by: SZEDER Gábor <szeder.dev@gmail.com>
Helped-by: Randall Becker <rsbecker@nexbridge.com>
Helped-by: Phillip Wood <phillip.wood123@gmail.com>
Suggested-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/config/safe.txt | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/config/safe.txt b/Documentation/config/safe.txt index 6d764fe0cc..c6ebd1674d 100644 --- a/Documentation/config/safe.txt +++ b/Documentation/config/safe.txt @@ -26,3 +26,16 @@ directory was listed in the `safe.directory` list. If `safe.directory=*` is set in system config and you want to re-enable this protection, then initialize your list with an empty value before listing the repositories that you deem safe. ++ +As explained, Git only allows you to access repositories owned by +yourself, i.e. the user who is running Git, by default. When Git +is running as 'root' in a non Windows platform that provides sudo, + however, git checks the SUDO_UID environment variable that sudo creates +and will allow access to the uid recorded as its value instead. +This is to make it easy to perform a common sequence during installation +"make && sudo make install". A git process running under 'sudo' runs as +'root' but the 'sudo' command exports the environment variable to record +which id the original user has. +If that is not what you would prefer and want git to only trust +repositories that are owned by root instead, then you must remove +the `SUDO_UID` variable from root's environment before invoking git. |