On Tue, May 24, 2022 at 7:51 AM Kevin Locke <kevin@xxxxxxxxxxxxxxx> wrote:
>
> Prior to Git 2.35.0, git could be run from an inaccessible working
> directory so long as the git repository specified by options and/or
> environment variables was accessible. For example:
>
> git init repo
> mkdir -p a/b
> cd a/b
> chmod u-x ..
> git -C "${PWD%/a/b}/repo" status
>
> If this example seems a bit contrived, consider running with the
> repository owner as a substitute UID (e.g. with runuser(1) or sudo(8))
> without ensuring the working directory is accessible by that user.
>
> The code added by e6f8861bd4 ("setup: introduce
> startup_info->original_cwd") to preserve the working directory attempts
> to normalize the path using strbuf_realpath(). If that fails, as in the
> case above, it is treated as a fatal error.
>
> This commit treats strbuf_realpath() errors as non-fatal. If an error
> occurs, setup_original_cwd() will continue without applying removal
> prevention for cwd, resulting in the pre-2.35.0 behavior. The risk
> should be minimal, since git will not operate on a repository with
> inaccessible ancestors, this behavior is only known to occur when cwd is
> a descendant of the repository, an ancestor of cwd is inaccessible, and
> no ancestors of the repository are inaccessible.
>
> Signed-off-by: Kevin Locke <kevin@xxxxxxxxxxxxxxx>
> ---
>
> Notes:
> Changes since v2:
> * Use trace2_data_string(), rather than trace_printf(), to report
> realpath failure.
>
> Changes since v1:
> * Set startup_info->original_cwd = NULL when strbuf_realpath() fails,
> rather than setting it to the un-normalized path.
> * Add a trace message when realpath fails to aid debugging.
> * Remove potential realpath failure cause from comment before it.
> * Improve format for reference to e6f8861bd4 in commit message.
> * Clarify when the pre-2.35.0 behavior may occur as a result of this
> commit in the commit message.
> * Remove 'Fixes:' tag from commit message.
>
> setup.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/setup.c b/setup.c
> index a7b36f3ffbf..38bd55cbac1 100644
> --- a/setup.c
> +++ b/setup.c
> @@ -458,11 +458,19 @@ static void setup_original_cwd(void)
> * not startup_info->original_cwd.
> */
>
> - /* Normalize the directory */
> - strbuf_realpath(&tmp, tmp_original_cwd, 1);
> - free((char*)tmp_original_cwd);
> - tmp_original_cwd = NULL;
> - startup_info->original_cwd = strbuf_detach(&tmp, NULL);
> + /* Try to normalize the directory. */
> + if (strbuf_realpath(&tmp, tmp_original_cwd, 0)) {
> + free((char*)tmp_original_cwd);
> + tmp_original_cwd = NULL;
> + startup_info->original_cwd = strbuf_detach(&tmp, NULL);
> + } else {
> + trace2_data_string("setup", the_repository,
> + "realpath-path", tmp_original_cwd);
> + trace2_data_string("setup", the_repository,
> + "realpath-failure", strerror(errno));
> + tmp_original_cwd = NULL;
> + goto no_prevention_needed;
> + }
>
> /*
> * Get our worktree; we only protect the current working directory
> --
> 2.35.1
Looks good to me:
Reviewed-by: Elijah Newren <newren@xxxxxxxxx>
