Bug 886116

Summary:	IPv6 networking breaks when loopback is set down and up
Product:	[Fedora] Fedora	Reporter:	Pavel Šimerda (pavlix) <psimerda>
Component:	kernel	Assignee:	Jiri Pirko <jpirko>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	17	CC:	gansalmon, itamar, jonathan, jpirko, kernel-maint, madhu.chinakonda, rkhan
Target Milestone:	---	Keywords:	Reopened
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2013-06-12 13:01:01 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	880347

Description Pavel Šimerda (pavlix) 2012-12-11 14:43:23 UTC

I am reproducing this on a local IPv6-enabled network, setting my global IPv6 address automatically using router advertisements. I don't yet know whether this is strictly related to autoconf or not, but I can test it if required.

Steps to reproduce:

1) Acquire IPv6 address through SLAAC (I'm currently using NetworkManager but this is done in kernel anyway)

2) View your own IP address and try to ping6 it. It should work.

3) ip link set lo down

4) ip link set lo up

5) Try pinging your global IPv6 address again.

Expected results:

#5 should work, just like #2 did

Actual results:

#5 doesn't work, ping gives no feedback about what happened

Notes:

Testing it with firewall enabled or disabled, it doesn't make a difference.

Comment 1 Pavel Šimerda (pavlix) 2012-12-11 14:47:45 UTC

Pinging ::1 works, though.

Comment 2 Pavel Šimerda (pavlix) 2012-12-11 14:49:42 UTC

Tested with kernel 3.6.7-4.fc17.x86_64

Comment 3 Jiri Pirko 2012-12-19 12:18:59 UTC

can you please provide output of "ip a" in state 2), 3), 4) ? Thanks.

Comment 4 Josh Boyer 2013-03-28 17:13:07 UTC

This bug is being closed with INSUFFICIENT_DATA as there has not been a
response in 2 weeks.  If you are still experiencing this issue,
please reopen and attach the relevant data from the latest kernel you are
running and any data that might have been requested previously.

Comment 5 Pavel Šimerda (pavlix) 2013-03-29 10:21:22 UTC

Output of 'ip address', I'm afraid it won't help much, though, as the problem is most probably internal to the kernel.

2)

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
    link/ether 00:1d:72:88:56:36 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::21d:72ff:fe88:5636/64 scope link 
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 00:1f:3c:1b:9e:5e brd ff:ff:ff:ff:ff:ff
    inet 84.246.161.89/28 brd 84.246.161.95 scope global wlan0
    inet6 2a00:1268:1ff:f001:21f:3cff:fe1b:9e5e/64 scope global dynamic 
       valid_lft 86396sec preferred_lft 14396sec
    inet6 fe80::21f:3cff:fe1b:9e5e/64 scope link 
       valid_lft forever preferred_lft forever
704: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1360 qdisc pfifo_fast state UNKNOWN qlen 100
    link/none 
    inet 10.36.116.23/22 brd 10.36.119.255 scope global tun0

3)

1: lo: <LOOPBACK> mtu 65536 qdisc noqueue state DOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
    link/ether 00:1d:72:88:56:36 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::21d:72ff:fe88:5636/64 scope link 
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 00:1f:3c:1b:9e:5e brd ff:ff:ff:ff:ff:ff
    inet 84.246.161.89/28 brd 84.246.161.95 scope global wlan0
    inet6 2a00:1268:1ff:f001:21f:3cff:fe1b:9e5e/64 scope global dynamic 
       valid_lft 86394sec preferred_lft 14394sec
    inet6 fe80::21f:3cff:fe1b:9e5e/64 scope link 
       valid_lft forever preferred_lft forever
704: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1360 qdisc pfifo_fast state UNKNOWN qlen 100
    link/none 
    inet 10.36.116.23/22 brd 10.36.119.255 scope global tun0

4)

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
    link/ether 00:1d:72:88:56:36 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::21d:72ff:fe88:5636/64 scope link 
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 00:1f:3c:1b:9e:5e brd ff:ff:ff:ff:ff:ff
    inet 84.246.161.89/28 brd 84.246.161.95 scope global wlan0
    inet6 2a00:1268:1ff:f001:21f:3cff:fe1b:9e5e/64 scope global dynamic 
       valid_lft 86374sec preferred_lft 14374sec
    inet6 fe80::21f:3cff:fe1b:9e5e/64 scope link 
       valid_lft forever preferred_lft forever
704: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1360 qdisc pfifo_fast state UNKNOWN qlen 100
    link/none 
    inet 10.36.116.23/22 brd 10.36.119.255 scope global tun0

Comment 6 Jiri Pirko 2013-06-12 13:01:01 UTC

Fixed by:

commit 25fb6ca4ed9cad72f14f61629b68dc03c0d9713f
Author: Balakumaran Kannan <kumaran.4353>
Date:   Tue Apr 2 16:15:05 2013 +0530

    net IPv6 : Fix broken IPv6 routing table after loopback down-up


I tested with F18, 3.9.4-200.fc18.x86_64 kernel, issue is not present.