Date: Mon, 10 Apr 2017 07:43:18 -0700 From: Maxim Sobolev <sobomax@freebsd.org> To: Ed Schouten <ed@nuxi.nl> Cc: Alexander Kabaev <kabaev@gmail.com>, Ed Schouten <ed@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org, mjg@freebsd.org, gnn@freebsd.org, network@freebsd.org Subject: On shutting down UDP socket [Re: svn commit: r285910 - in head: lib/libc/sys sys/kern sys/sys] Message-ID: <CAH7qZfvuaiFmUvb0B0TuYds7eqh94u%2Bo2h9_TzMHst_dZjn09Q@mail.gmail.com>
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Hi Guys, I am sorry to bring this old thread up, but I think Ed's comparison with other OSes here and in the relevant differential was not entirely correct. What linux does (tested with 4.4.0) when UDP socket is shut down is actually shutting down receiving end, so any threads that are blocked in recv() on that socket return. Still shutdown() system call itself returns ENOTCONN. FreeBSD on the other hand does not do anything for the socket, so that the threads just hang. I am pretty sure there are at least some software out there that relies on that behavior, at least in our case we do. Bumped into this after upgrading to the 11.0. Therefore, I am curious about possibility to make our behavior match that of Linux's, so we are not the odd one with regards to this, that is return an error but still shutdown the socket? Small test case is attached. Both FreeBSD 10.3 and Linux 4.4.0 pass (albeit Linux's shutdown() returns with an error), FreeBSD 11.0 fails. -Max On Sun, Aug 9, 2015 at 6:08 AM, Ed Schouten <ed@nuxi.nl> wrote: > Hi Alexander, > > 2015-08-09 14:55 GMT+02:00 Alexander Kabaev <kabaev@gmail.com>: > > On Sun, 9 Aug 2015 09:37:13 +0200 > > It most definitely does work, this is what I have done to get my > > network scripts work again. I wonder if there are other means of > > restricting raw sockets that can be used to achieve the result > > authors of rtsold had hoped or? > > Yes, there sure are. We could for example call cap_rights_limit() on > the socket and whitelist the exacty set of actions that the program > needs. > > That said, it wouldn't make a difference in the end. It looks like > rtsol/rtsold don't seem to drop any privileges or switch credentials > after startup, assuming I haven't overlooked anything. Even if we were > to restrict the raw socket, the process could always open a new one > later on. > > I think it would make sense for now to just commit the patch that I > proposed. Will push it into the tree tomorrow. > > Thanks, > -- > Ed Schouten <ed@nuxi.nl> > Nuxi, 's-Hertogenbosch, the Netherlands > KvK/VAT number: 62051717 > >
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