Jeff King <peff@xxxxxxxx> writes:
> Hmm. I think this commit message isn't quite right, because we also
> skipped the patches to touch gitignore/gitattributes in verify_path().
>
> Are you thinking we should resurrect that behavior[1], too, or just
> protect at the fsck level?
>
>> It was omitted from that series because it does not address any known
>> exploit, but to me it seems worthwhile anyway:
>>
>> - if a client enables transfer.fsckObjects, this helps them protect
>> themselves against weird input that does *not* have a known exploit
>> attached, to
>>
>> - it generally feels more simple and robust. Git-related tools can
>> benefit from this kind of check as an indication of input they can
>> bail out on instead of trying to support.
>
> I think I may just be restating your two points above, but what I'd
> argue is:
>
> - even though there's no known-interesting exploit, this can cause Git
> to unexpectedly read arbitrary files outside of the repository
> directory. That in itself isn't necessarily evil, but it's weird.
>
> - there are potentially non-malicious bugs here, where we try to read
> .gitattributes out of the index, but obviously don't follow symlinks
> there
FWIW, you two can count me as the third person who agrees with the
above points.
> [1] This wasn't a separate patch, but just an early iteration of the
> "ban symlinks in .gitmodules" patch. I think the incremental is
> just:
>
> diff --git a/read-cache.c b/read-cache.c
> index bfff271a3d..121c0bec69 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -937,7 +937,9 @@ static int verify_dotfile(const char *rest, unsigned mode)
> return 0;
> if (S_ISLNK(mode)) {
> rest += 3;
> - if (skip_iprefix(rest, "modules", &rest) &&
> + if ((skip_iprefix(rest, "modules", &rest) ||
> + skip_iprefix(rest, "ignore", &rest) ||
> + skip_iprefix(rest, "attributes", &rest)) &&
> (*rest == '\0' || is_dir_sep(*rest)))
> return 0;
> }
OK.
> @@ -966,7 +968,9 @@ int verify_path(const char *path, unsigned mode)
> if (is_hfs_dotgit(path))
> return 0;
> if (S_ISLNK(mode)) {
> - if (is_hfs_dotgitmodules(path))
> + if (is_hfs_dotgitmodules(path) ||
> + is_hfs_dotgitignore(path) ||
> + is_hfs_dotgitattributes(path))
> return 0;
> }
> }
> @@ -974,7 +978,9 @@ int verify_path(const char *path, unsigned mode)
> if (is_ntfs_dotgit(path))
> return 0;
> if (S_ISLNK(mode)) {
> - if (is_ntfs_dotgitmodules(path))
> + if (is_ntfs_dotgitmodules(path) ||
> + is_ntfs_dotgitignore(path) ||
> + is_ntfs_dotgitattributes(path))
> return 0;
Curious that we already have these helpers, nobody seems to call
them in the current codebase, and we haven't seen the "these are
unused" linter message on the list for a while ;-).
