From: Jeff King <peff@peff.net>
To: Michael Haggerty <mhagger@alum.mit.edu>
Cc: Junio C Hamano <gitster@pobox.com>,
git@vger.kernel.org, David Turner <novalis@novalis.org>
Subject: Re: [PATCH v3 21/23] try_remove_empty_parents(): don't accommodate consecutive slashes
Date: Mon, 2 Jan 2017 13:26:39 -0500 [thread overview]
Message-ID: <20170102182639.c53flvqdkb4kjuuh@sigill.intra.peff.net> (raw)
In-Reply-To: <5051c78e-51f9-becd-e1a6-9c0b781d6912@alum.mit.edu>
On Mon, Jan 02, 2017 at 07:06:32PM +0100, Michael Haggerty wrote:
> My assumption was that only valid reference names should ever be allowed
> to be inserted into a `ref_transaction` entry. But Peff is right that
> sometimes the reference name is checked by `refname_is_safe()` rather
> than `check_refname_format()`. Let's audit this more carefully...
>
> * `ref_transaction_add_update()` relies on its caller doing the check
> (this fact is documented). Its callers are:
> * `ref_transaction_update()` (the usual codepath), which checks the
> reference itself using either check_refname_format() or
> refname_is_safe() depending on what kind of update it is.
> * `split_head_update()` passes the literal string "HEAD".
> * `split_symref_update()` picks apart reference updates that go
> through existing symbolic references. As such I don't think they
> are an attack surface. It doesn't do any checking itself (here
> we're talking about its `referent` argument). It has only one
> caller:
> * `lock_ref_for_update()`, which gets `referent` from:
> * `files_read_raw_ref()`, which gets the value either:
> * by reading a filesystem-level symlink's contents and
> checking it with `check_refname_format()`, or
> * reading a symref from the filesystem. In this case, *the
> value is not checked*.
>
> Obviously this chain of custody is disconcertingly long and complicated.
> And the gap for symrefs should probably be fixed, even though they are
> hopefully trustworthy.
Thanks as always for a careful analysis. I agree it seems like a bug
that symlinks are checked but symrefs are not.
> I think the best thing to do is to drop this patch from the patch
> series, and address these checks in a separate series. (There are more
> known problems in this area, for example that the checks in
> `check_refname_format()` are not a strict superset of the checks in
> `refname_is_safe()`.)
Sounds like a good plan. I'd be very happy if the "superset" mismatch is
fixed. It seems like it has come up in our discussions more than once.
-Peff
next prev parent reply other threads:[~2017-01-02 18:28 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-31 3:12 [PATCH v3 00/23] Delete directories left empty after ref deletion Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 01/23] files_rename_ref(): tidy up whitespace Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 02/23] t5505: use "for-each-ref" to test for the non-existence of references Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 03/23] safe_create_leading_directories_const(): preserve errno Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 04/23] safe_create_leading_directories(): set errno on SCLD_EXISTS Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 05/23] raceproof_create_file(): new function Michael Haggerty
2016-12-31 6:11 ` Jeff King
2016-12-31 7:42 ` Michael Haggerty
2017-01-01 2:07 ` Junio C Hamano
2016-12-31 3:12 ` [PATCH v3 06/23] lock_ref_sha1_basic(): inline constant Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 07/23] lock_ref_sha1_basic(): use raceproof_create_file() Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 08/23] rename_tmp_log(): " Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 09/23] rename_tmp_log(): improve error reporting Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 10/23] log_ref_write(): inline function Michael Haggerty
2017-01-01 2:09 ` Junio C Hamano
2017-01-01 8:41 ` Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 11/23] log_ref_setup(): separate code for create vs non-create Michael Haggerty
2016-12-31 6:26 ` Jeff King
2016-12-31 7:52 ` Michael Haggerty
2017-01-01 3:28 ` Junio C Hamano
2017-01-01 8:45 ` Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 12/23] log_ref_setup(): improve robustness against races Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 13/23] log_ref_setup(): pass the open file descriptor back to the caller Michael Haggerty
2016-12-31 6:32 ` Jeff King
2016-12-31 7:58 ` Michael Haggerty
2016-12-31 17:58 ` Jeff King
2017-01-01 10:36 ` Junio C Hamano
2016-12-31 3:12 ` [PATCH v3 14/23] log_ref_write_1(): don't depend on logfile argument Michael Haggerty
2016-12-31 6:35 ` Jeff King
2016-12-31 8:01 ` Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 15/23] log_ref_setup(): manage the name of the reflog file internally Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 16/23] log_ref_write_1(): inline function Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 17/23] delete_ref_loose(): derive loose reference path from lock Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 18/23] delete_ref_loose(): inline function Michael Haggerty
2016-12-31 3:12 ` [PATCH v3 19/23] try_remove_empty_parents(): rename parameter "name" -> "refname" Michael Haggerty
2016-12-31 3:13 ` [PATCH v3 20/23] try_remove_empty_parents(): don't trash argument contents Michael Haggerty
2016-12-31 6:40 ` Jeff King
2017-01-02 16:27 ` Michael Haggerty
2017-01-02 17:10 ` Jeff King
2016-12-31 3:13 ` [PATCH v3 21/23] try_remove_empty_parents(): don't accommodate consecutive slashes Michael Haggerty
2017-01-01 2:30 ` Junio C Hamano
2017-01-01 5:59 ` Jeff King
2017-01-02 18:06 ` Michael Haggerty
2017-01-02 18:26 ` Jeff King [this message]
2016-12-31 3:13 ` [PATCH v3 22/23] try_remove_empty_parents(): teach to remove parents of reflogs, too Michael Haggerty
2016-12-31 3:13 ` [PATCH v3 23/23] files_transaction_commit(): clean up empty directories Michael Haggerty
2016-12-31 6:47 ` [PATCH v3 00/23] Delete directories left empty after ref deletion Jeff King
2017-01-01 2:32 ` Junio C Hamano
2017-01-01 9:24 ` Jacob Keller
2017-01-01 9:26 ` Jacob Keller
2017-01-01 12:43 ` Philip Oakley
2017-01-01 20:36 ` Jacob Keller
2017-01-02 4:19 ` Jeff King
2017-01-02 18:14 ` Michael Haggerty
2017-01-02 18:54 ` Jacob Keller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170102182639.c53flvqdkb4kjuuh@sigill.intra.peff.net \
--to=peff@peff.net \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=mhagger@alum.mit.edu \
--cc=novalis@novalis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).