Date: Thu, 9 Jul 2020 22:00:16 +0200 From: Michael Tuexen <tuexen@freebsd.org> To: Doug Hardie <bc979@lafn.org> Cc: Mark Johnston <markj@freebsd.org>, freebsd-net@freebsd.org Subject: Re: making SCTP loadable and removing it from GENERIC Message-ID: <5C210E52-0447-450C-B515-70FDC5EA29F4@freebsd.org> In-Reply-To: <63F4446F-DECF-4DE8-99CA-EC8755A5D4A1@mail.sermon-archive.info> References: <20200709151300.GC8947@raichu> <63F4446F-DECF-4DE8-99CA-EC8755A5D4A1@mail.sermon-archive.info>
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> On 9. Jul 2020, at 21:44, Doug Hardie <bc979@lafn.org> wrote: >=20 >> On 9 July 2020, at 08:13, Mark Johnston <markj@freebsd.org> 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. = What is going to happen if you run an application that uses SCTP and the = module is not loaded? What will remind=20 The socket() call would fail. What then happens depend on the error = handling in your application. > me how to fix the issue? I am not likely to remember about this 6 = months from now. I'm not sure, but I guess Mark is planning to MFC the changes to = stable/12. So you would test this when upgrading to 12.2, I guess. I suggested to document what user have to do (assuming they read UPGRADING and it gets documented there. Best regards Michael >=20 > -- Doug
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