From owner-cvs-all@FreeBSD.ORG Sun Apr 4 03:02:57 2004 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 44D2716A4CE; Sun, 4 Apr 2004 03:02:57 -0700 (PDT) Received: from tigra.ip.net.ua (tigra.ip.net.ua [82.193.96.10]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6893A43D60; Sun, 4 Apr 2004 03:02:53 -0700 (PDT) (envelope-from ru@ip.net.ua) Received: from heffalump.ip.net.ua (heffalump.ip.net.ua [82.193.96.213]) by tigra.ip.net.ua (8.12.11/8.12.11) with ESMTP id i34A6ZK6074301 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 4 Apr 2004 13:06:37 +0300 (EEST) (envelope-from ru@ip.net.ua) Received: (from ru@localhost) by heffalump.ip.net.ua (8.12.11/8.12.11) id i34A2icO016508; Sun, 4 Apr 2004 13:02:44 +0300 (EEST) (envelope-from ru) Date: Sun, 4 Apr 2004 13:02:43 +0300 From: Ruslan Ermilov To: Brooks Davis Message-ID: <20040404100243.GA16434@ip.net.ua> References: <200403221424.i2MEOQYK057524@repoman.freebsd.org> <20040330220349.GA97921@ip.net.ua> <20040330232517.GA19416@Odin.AC.HMC.Edu> <20040331072756.GA14337@ip.net.ua> <20040403085651.GA96868@ip.net.ua> <20040404051126.GA22393@Odin.AC.HMC.Edu> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="vkogqOf2sHV7VnPd" Content-Disposition: inline In-Reply-To: <20040404051126.GA22393@Odin.AC.HMC.Edu> User-Agent: Mutt/1.5.6i X-Virus-Scanned: by amavisd-new X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-exp) cc: cvs-src@freebsd.org cc: src-committers@freebsd.org cc: Robert Watson cc: cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/net if_gif.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Apr 2004 10:02:57 -0000 --vkogqOf2sHV7VnPd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Apr 03, 2004 at 09:11:26PM -0800, Brooks Davis wrote: > On Sat, Apr 03, 2004 at 11:56:51AM +0300, Ruslan Ermilov wrote: > > On Wed, Mar 31, 2004 at 10:27:56AM +0300, Ruslan Ermilov wrote: > > > On Tue, Mar 30, 2004 at 03:25:17PM -0800, Brooks Davis wrote: > > > > On Wed, Mar 31, 2004 at 01:03:49AM +0300, Ruslan Ermilov wrote: > > > > > On Mon, Mar 22, 2004 at 06:24:26AM -0800, Robert Watson wrote: > > > > > > rwatson 2004/03/22 06:24:26 PST > > > > > >=20 > > > > > > FreeBSD src repository > > > > > >=20 > > > > > > Modified files: > > > > > > sys/net if_gif.c=20 > > > > > > Log: > > > > > > Move "called", a static function variable used to detect recu= rsive > > > > > > processing with gif interfaces, to a global variable named "g= if_called". > > > > > > Add an annotation that this approach will not work with a ree= ntrant > > > > > > network stack, and that we should instead use packet tags to = detect > > > > > > excessive recursive processing. > > > > > > =20 > > > > > > Revision Changes Path > > > > > > 1.42 +11 -4 src/sys/net/if_gif.c > > > > > >=20 > > > > > Implemented this in the attached patch. Note when testing: setti= ng > > > > > net.link.gif.max_nesting too high (>20 on my system) and triggeri= ng > > > > > the recursion causes the kernel stack exhaustion. > > > >=20 > > > > Why not just do what OpenBSD does and do actual loop detection? Th= is > > > > gets rid of the nesting count hack which isn't really what you want= to > > > > measure anyway. > > > >=20 > > > > http://www.openbsd.org/cgi-bin/cvsweb/src/sys/net/if_gif.c.diff?r1= =3D1.18&r2=3D1.19 > > > >=20 > > > Good idea. I will implement it and repost the updated patch here. > > >=20 > > Actually, just replacing nesting limiter with loop detection was a > > bad idea, so I didn't follow it. It's a bad idea because you might > > have many nesting (but not looping) gif interfaces, and this will > > still cause panic by exhausting the kernel stack. Instead, I have > > combined both checks. Please review the attached patch. >=20 > Unless you can automaticly choose a valid value for max_gif_nesting, I > think it should be taken out and shot. Unless you can do that, there's > nothing you can do to prevent the admin from making a configuration that > blows out the stack so why keep the extra annoyance of gif_max_nest > around? It won't do anything to prevent the panic and will break things > in perfectly valid cases. If we're really worried about the stack > issue, forcing a requeue instead of processing to completion any time > we're nested makes more sense to me. >=20 Unfortunately, there's no such thing as the IP output queue. Anyway, I'm going to commit my version now. If you want to shot the nesting limit, I'm fine with it, but please _you_ do it. ;) Cheers, --=20 Ruslan Ermilov ru@FreeBSD.org FreeBSD committer --vkogqOf2sHV7VnPd Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFAb91DUkv4P6juNwoRAq0WAJ9KZaep3qcYkCFFfAryo04OoQATQgCfVhq/ GtqyHCvsUt3KuLLxkYbrXh4= =ifzQ -----END PGP SIGNATURE----- --vkogqOf2sHV7VnPd--