From owner-freebsd-net@freebsd.org Thu Jul 9 21:45:41 2020 Return-Path: Delivered-To: freebsd-net@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id EC8F5357780 for ; Thu, 9 Jul 2020 21:45:41 +0000 (UTC) (envelope-from tuexen@freebsd.org) Received: from drew.franken.de (drew.ipv6.franken.de [IPv6:2001:638:a02:a001:20e:cff:fe4a:feaa]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.franken.de", Issuer "Sectigo RSA Domain Validation Secure Server CA" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4B2qVF3ZWTz4gLS; Thu, 9 Jul 2020 21:45:41 +0000 (UTC) (envelope-from tuexen@freebsd.org) Received: from mb.fritz.box (ip4d15f5fc.dynamic.kabel-deutschland.de [77.21.245.252]) (Authenticated sender: macmic) by mail-n.franken.de (Postfix) with ESMTPSA id 246FA7220B82B; Thu, 9 Jul 2020 23:45:35 +0200 (CEST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.80.23.2.2\)) Subject: Re: making SCTP loadable and removing it from GENERIC From: Michael Tuexen In-Reply-To: <3DC5AC46-604E-4CB4-93EC-6421ED575DBB@mail.sermon-archive.info> Date: Thu, 9 Jul 2020 23:45:34 +0200 Cc: Mark Johnston , freebsd-net@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: <814D36BF-46D9-4093-9D7C-36A79771C742@freebsd.org> References: <20200709151300.GC8947@raichu> <63F4446F-DECF-4DE8-99CA-EC8755A5D4A1@mail.sermon-archive.info> <20200709201044.GG8947@raichu> <3DC5AC46-604E-4CB4-93EC-6421ED575DBB@mail.sermon-archive.info> To: Doug Hardie X-Mailer: Apple Mail (2.3608.80.23.2.2) X-Spam-Status: No, score=-2.9 required=5.0 tests=ALL_TRUSTED,BAYES_00 autolearn=disabled version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on mail-n.franken.de X-Rspamd-Queue-Id: 4B2qVF3ZWTz4gLS X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [0.00 / 15.00]; ASN(0.00)[asn:680, ipnet:2001:638::/32, country:DE]; local_wl_from(0.00)[freebsd.org] X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 Jul 2020 21:45:42 -0000 > On 9. Jul 2020, at 23:15, Doug Hardie wrote: >=20 >> On 9 July 2020, at 13:10, Mark Johnston wrote: >>=20 >> On Thu, Jul 09, 2020 at 12:44:25PM -0700, Doug Hardie wrote: >>>> On 9 July 2020, at 08:13, Mark Johnston wrote: >>>>=20 >>>> Hi, >>>>=20 >>>> I spent some time working on making it possible to load the SCTP = stack >>>> as a kernel module, the same as we do today with IPSec. There is = one >>>> patch remaining to be committed before that can be done in head. = One >>>> caveat is that the module can't be unloaded, as some work is needed = to >>>> make this safe. However, this obviously isn't a regression. >>>>=20 >>>> The work is based on the observations that: >>>> 1) the in-kernel SCTP stack is not widely used (I know that the = same >>>> code is used in some userland applications), and >>>> 2) the SCTP stack is quite large, most FreeBSD kernel developers = are >>>> unfamiliar with it, and bugs in it can easily lead to security = holes. >>>>=20 >>>> Michael has done a lot of work to fix issues in the SCTP code, >>>> particularly those found by syzkaller, but given that in-kernel = SCTP has >>>> few users (almost certainly fewer than IPSec), it seems reasonable = to >>>> require users to opt in to having an SCTP stack with a simple = "kldload >>>> sctp". Thus, once the last patch is committed I would like to = propose >>>> removing "options SCTP" from GENERIC kernel configs in head, = replacing >>>> it with "options SCTP_SUPPORT" to enable sctp.ko to be loaded. >>>>=20 >>>> I am wondering if anyone has any objections to or concerns about = this >>>> proposal. Any feedback is appreciated. >>>=20 >>> I have a number of systems using SCTP. It is a key part of a = distributed application. As a user of SCTP, I have a slight objection = to removing it from the kernel. It would require me to remember when = setting up a new system to enable that. I am not likely to remember. >>=20 >> To be clear, with the proposed change SCTP can be loaded at boot by >> adding a single line: sctp_load=3D"YES" to /boot/loader.conf, or >> kld_list=3D"sctp" to /etc/rc.conf. Also, the change will not be = present >> in a release until 13.0 or possibly 12.2, which provides plenty of = time, >> and the release notes will reflect the change. >>=20 >> I was really looking for objections pointing out that a dynamically >> loaded SCTP stack would prevent or inhibit some workflow. Relying on >> being able to configure systems from memory rather than using a >> checklist or some automated configuration management does not seem to = be >> a good reason for keeping SCTP in the kernel. >>=20 >>> What is going to happen if you run an application that uses SCTP and = the module is not loaded? >>=20 >> An attempt to create an SCTP socket will fail with EPROTONOSUPPORT, >> "Protocol not supported". >>=20 >>> What will remind me how to fix the issue? I am not likely to = remember about this 6 months from now. >>=20 >> Hopefully "protocol not supported" is a sufficiently descriptive = error >> message.=20 >=20 > Actually, the users of these systems would have no clue about that = message. All they would figure out is that the system is down and they = can't do their job and bitch to the CEO. I am going to assume that that = error will be produced by the socket call and I have added code to check = for it and email me if it occurs. I believe that the only viable = approach for us is the rc.conf solution as some of these systems are = rhapsberry pi 3s which I understand don't use the loader.conf file. OK. Do you control the kernel which is running on the machines? If that = is the case, you could add a line to the kernel config, rebuild the kernel and use = that custom kernel with compiled-in SCTP support. That is still possible. >=20 > One of the configurations we are considering is for each user to have = their own Rhapsberry Pi and eliminate the central server. All data is = replicated between all the machines so there is no need for a central = server anymore. If I can make that work, it would be a large cost = savings for my client. If that gets rid of the need to use SCTP, that would also work. Best regards Michael >=20 > -- Doug >=20 >=20 > _______________________________________________ > freebsd-net@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"