Re: [PATCH v2] setup: tighten ownership checks post CVE-2022-24765

[Derrick Stolee <derrickstolee@github.com>]

On 5/5/2022 9:14 AM, Derrick Stolee wrote:
> On 5/4/2022 8:50 PM, Carlo Marcelo Arenas Belón wrote:
>> -static int ensure_valid_ownership(const char *path)
>> +static int ensure_valid_ownership(const char *worktree, const char *gitdir)
>>  {
>> -	struct safe_directory_data data = { .path = path };
>> +	struct safe_directory_data data = { .path = worktree };

This also seems a bit backwards to me. I think bare repos will have a NULL
worktree, but all repos will have a gitdir. I think what we really want
is this:

	.path = worktree ? worktree : gitdir

And that might affect the callers of this method allowing the worktree to
be NULL.

> I think you should remove check_path and instead do the following:
> 
> 	if (!git_env_bool("GIT_TEST_ASSUME_DIFFERENT_OWNER", 0) &&
> 	    is_path_owned_by_current_user(worktree) &&
> 	    (!gitdir || is_path_owned_by_current_user(gitdir)))
>  		return 1;

But that changes my logic here to instead be

 	if (!git_env_bool("GIT_TEST_ASSUME_DIFFERENT_OWNER", 0) &&
	    is_path_owned_by_current_user(gitdir) &&
	    (!worktree|| is_path_owned_by_current_user(worktree)))
  		return 1;

Thanks,
-Stolee