From owner-freebsd-hackers Fri Feb 21 15:27:46 2003 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 61CC137B401; Fri, 21 Feb 2003 15:27:45 -0800 (PST) Received: from bluejay.mail.pas.earthlink.net (bluejay.mail.pas.earthlink.net [207.217.120.218]) by mx1.FreeBSD.org (Postfix) with ESMTP id 73E8443FBD; Fri, 21 Feb 2003 15:27:44 -0800 (PST) (envelope-from tlambert2@mindspring.com) Received: from pool0179.cvx21-bradley.dialup.earthlink.net ([209.179.192.179] helo=mindspring.com) by bluejay.mail.pas.earthlink.net with asmtp (SSLv3:RC4-MD5:128) (Exim 3.33 #1) id 18mMZq-0000Xd-00; Fri, 21 Feb 2003 15:27:35 -0800 Message-ID: <3E56B589.2E15F3C3@mindspring.com> Date: Fri, 21 Feb 2003 15:26:01 -0800 From: Terry Lambert X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Yevgeniy Aleynikov Cc: Kirk McKusick , Matt Dillon , Ian Dowse , peter@FreeBSD.ORG, ache@FreeBSD.ORG, Ken Pizzini , hackers@FreeBSD.ORG, security-officer@FreeBSD.ORG, nectar@FreeBSD.ORG, jedgar@FreeBSD.ORG, rwatson@FreeBSD.ORG, imp@FreeBSD.ORG, security-team@FreeBSD.ORG, wes@FreeBSD.ORG, guido@FreeBSD.ORG Subject: Re: bleh. Re: ufs_rename panic References: <200302200101.h1K11ZFL056229@beastie.mckusick.com> <3E56A683.5070504@infospace.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-ELNK-Trace: b1a02af9316fbb217a47c185c03b154d40683398e744b8a46541ca638c83f647b7ffba3ec76f83c2350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Yevgeniy Aleynikov wrote: > As pointed by Ken - we do have alot of file renames (qmail). > But 2-nd solution, directory-only rename serialization, probably won't > affect performance as much. > > But i believe it's not only us who's gonna have problem when exploit > code will be known by everybody sooner or later.... Dan's non-atomicity assumption on renames is incorrect. Even if it's were correct, it's possible to recover fully following a failure, because metadata updates are ordered (there is a real synchronization between dependent operations). I think that a workaround would be to comment the directory fsync() code out of qmail, which apparently thinks it's running on extfs or an async mounted FFS. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message