Date: Fri, 27 Jul 2007 09:43:53 +0200 From: Max Laier <max@love2party.net> To: Kris Kennaway <kris@obsecurity.org> Cc: Robert Watson <rwatson@freebsd.org>, Julian Elischer <julian@elischer.org>, freebsd-arch@freebsd.org Subject: Re: Attention pf/ipfw users with uid/gid/jail rules (Re: Reminder: NET_NEEDS_GIANT, debug.mpsafenet going away in 7.0) Message-ID: <200707270944.08668.max@love2party.net> In-Reply-To: <20070727024107.GA69300@rot26.obsecurity.org> References: <20070717131518.G1177@fledge.watson.org> <46A100C2.1030606@elischer.org> <20070727024107.GA69300@rot26.obsecurity.org>
next in thread | previous in thread | raw e-mail | index | archive | help
--nextPart1297215.7gjCYQZVqa Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Friday 27 July 2007, Kris Kennaway wrote: > On Fri, Jul 20, 2007 at 11:36:50AM -0700, Julian Elischer wrote: > > Robert Watson wrote: > > >On Tue, 17 Jul 2007, Max Laier wrote: > > > > > >So far I have had 0 (zero) reports of problems since this thread > > > began. Could people using uid/gid/jail rules with ipfw or pf on 7.x > > > *please* try running their firewalls without debug.mpsafenet -- > > > ignore the witness warnings and/or disable witness, and let us know > > > if you experience deadlocks. We're reaching the very end of the > > > merge cycle for 7.0, and I would really like to remove the Giant > > > crutches (now effectively unused) from the network stack so it's > > > not part of the ABI/API, the code is simplified and cleaned up, > > > etc. > > > > does "problem" include a LOR message, or only a deadlock? > > I've seen plenty of the first, but not the second. > > Various users have reported definite deadlocks relating to uid/gid ^------^ ^------^ > firewall rules in the past. I don't think the strong wording is true. I have seen a few reports of=20 deadlocks in the past where debug.mpsafenet "fixed" the issue, but none=20 of the reporters where able to provide enough debugging details to=20 actually identify the culprit. Also note that a lot has changed since the early reports. What WITNESS is= =20 warning about now is something like: rlock(&lock1); mtx_lock(&lock2); mtx_unlock(&lock2); runlock(&lock1); vs. mtx_lock(&lock2); rlock(&lock1); runlock(&lock1); mtx_unlock(&lock2); It's obvious that this can't cause a deadlock unless there is a third=20 codepath that does either: wlock(&lock1); mtx_lock(&lock2); mtx_unlock(&lock2); wunlock(&lock1); or mtx_lock(&lock2); wlock(&lock1); wunlock(&lock1); mtx_unlock(&lock2); I have an idea how to teach WITNESS about this, but it's an awful hack,=20 yet. =2D-=20 /"\ Best regards, | mlaier@freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier@EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News --nextPart1297215.7gjCYQZVqa Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBGqaJIXyyEoT62BG0RAm1aAJ9odYqxJEIjxEMrbr+bG2r3jC5TsQCaAr5+ 9fVT+KOkkxdub/q9NyqKoj4= =mAop -----END PGP SIGNATURE----- --nextPart1297215.7gjCYQZVqa--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200707270944.08668.max>