Date: Tue, 17 Feb 2004 04:36:07 -0800 (PST) From: Alexander Motin <mav@alkar.net> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/62957: When created dummynet pipe on output router interface with lower MTU system stops to generate 'Fragment Needed but DF was Set' ICMP in cases when it must Message-ID: <200402171236.i1HCa7p2054112@www.freebsd.org> Resent-Message-ID: <200402171240.i1HCeKRU002449@freefall.freebsd.org>
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>Number: 62957
>Category: kern
>Synopsis: When created dummynet pipe on output router interface with lower MTU system stops to generate 'Fragment Needed but DF was Set' ICMP in cases when it must
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Feb 17 04:40:20 PST 2004
>Closed-Date:
>Last-Modified:
>Originator: Alexander Motin
>Release: 4.8 and 5.2
>Organization:
Alkar-Teleport ISP
>Environment:
FreeBSD ghsdr3-dp.alkar.net 4.8-RELEASE FreeBSD 4.8-RELEASE #2: Thu Oct 2 18:36:09 EEST 2003 povar@ghsdr3-dp.alkar.net:/usr/src/sys/compile/GHSDR2-DP i386
FreeBSD orphanage.alkar.net 5.2-RELEASE FreeBSD 5.2-RELEASE #0: Wed Jan 14 04:41:35 EET 2004 mav@orphanage.alkar.net:/usr/obj/usr/src/sys/orphanage i386
>Description:
When I create dummynet pipe on output router interface with lower MTU system stops to generate 'Fragment Needed but DF was Set' ICMP in cases when it must. If I create this pipe on incoming interface there is no problem.
>How-To-Repeat:
Take router with 2 interfaces and small MTU on one of them.
Create output dummynet pipe on interface with small MTU.
Send big packet with DF flag set.
>Fix:
Check result code of ip_output() in ip_dummynet.c and send requires ICMP message.
Here is no any check of result code:
case DN_TO_IP_OUT:
(void)ip_output((struct mbuf *)pkt, NULL, NULL, 0, NULL, NULL);
rt_unref (pkt->ro.ro_rt, __func__) ;
break ;
>Release-Note:
>Audit-Trail:
>Unformatted:
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