Date: Fri, 14 Apr 2017 23:58:55 -0700 From: Peter Wemm <peter@wemm.org> To: "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com> Cc: svn-src-all@freebsd.org, src-committers <src-committers@freebsd.org>, Hiroki Sato <hrs@freebsd.org>, Hiren Panchasara <hiren@freebsd.org>, svn-src-head@freebsd.org, Maxim Sobolev <sobomax@sippysoft.com> Subject: Re: svn commit: r316874 - head/sys/kern Message-ID: <11221477.gRA6BXfcIE@overcee.wemm.org> In-Reply-To: <CDFAE7DD-8F3A-43D9-AAD5-DF9FABEC4669@gmail.com> References: <201704141723.v3EHNS3B043902@repo.freebsd.org> <2109294.KVn8xeR1jZ@overcee.wemm.org> <CDFAE7DD-8F3A-43D9-AAD5-DF9FABEC4669@gmail.com>
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On Friday, April 14, 2017 08:13:52 PM Ngie Cooper wrote:
> > On Apr 14, 2017, at 20:12, Peter Wemm <peter@wemm.org> wrote:
> >=20
> > On Friday, April 14, 2017 07:36:55 PM Peter Wemm wrote:
> >> On Friday, April 14, 2017 02:14:16 PM Ngie Cooper wrote:
> >>>> On Apr 14, 2017, at 14:10, Maxim Sobolev <sobomax@sippysoft.com>=
wrote:
> >>>>=20
> >>>> Peter, Ngie,
> >>>>=20
> >>>> Looks like out of that refactoring came a logical bug that is pr=
esent
> >>>> in
> >>>> the head, which causes syslod to first to shutdown the socket fo=
r
> >>>> reading
> >>>> and then try to select/recv on it (which is somewhat stupid). An=
d that
> >>>> issue has been masked by shutdown() on datagram socket becoming
> >>>> effectively a NOP in 11 & head 20 months ago. It only affects he=
ad
> >>>> though, 11-stable still has the old code which does not include =
that
> >>>> half-closed socket into the select list. Attached patch is expec=
ted to
> >>>> fix head, Peter, it would be nice if you can give it a try (rest=
oring
> >>>> latest changes into uipc_sockets.c) and let me know if it helps.=
> >>>>=20
> >>>> Thanks!
> >>>=20
> >>> CCing hrs@ for input as he did the refactoring.
> >>> Thanks!
> >>> -Ngie
> >>>=20
> >>> PS LGTM with the change. Will wait for feedback from wemm@.
> >>=20
> >> This is definitely not working. I get ENOSPC and listen queue ov=
erflows
> >> on /var/run/logpriv now.
> >>=20
> >> Grabbing an old 10.3 /usr/sbin/syslogd and placing it on the top o=
f the
> >> 12.x one worked fine, aside from the include statements.
> >=20
> > This can't be right:
> > if (SecureMode || res->ai_family =3D=3D AF_LOCAL) {=
> > =20
> > /* Forbid communication in secure mode. */
> > if (shutdown(s, SHUT_RD) < 0 &&
> > =20
> > errno !=3D ENOTCONN) {
> > =20
> > logerror("shutdown");
> > if (!Debug)
> > =20
> > die(0);
> > =20
> > }
> > dprintf("listening on socket\n");
> > sl_recv =3D NULL;
> > =20
> > }
> >=20
> > This appears to disable unix domain sockets like /var/run/log and
> > /var/run/logpriv.
>=20
> ACK. This looks like a fun bug.
> -Ngie
I suspect it's meant to be "if (SecureMode && res->ai_family !=3D AF_LO=
CAL) {"=20
as a simple logic inversion error of another line earlier. However the=
re's an=20
awful lot of strange things in this code.
1) listen(s, 5) - on datagram sockets.
2) dprintf("shutdown") in code regardless of whether the shutdown is go=
ing to=20
happen.
3) dprintf("listening on socket") in code that only happens when we're =
NOT=20
going to listen.
4) dprintf("sending on socket") in the code path when we're going to li=
sten.
5) shutdown on all unix domain sockets, regardless of securemode..
This code block makes my head spin.
=2D-=20
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI=
6FJV
UTF-8: for when a ' or ... just won\342\200\231t do\342\200\246
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