Bug 235500

Summary: [netgraph] tunnel nesting limit hard coded
Product: Base System Reporter: i.bakirov
Component: kernAssignee: Gleb Smirnoff <glebius>
Status: Closed FIXED    
Severity: Affects Many People CC: ae, glebius
Priority: --- Keywords: patch
Version: CURRENT   
Hardware: Any   
OS: Any   
Attachments:
Description Flags
suggested patch none

Description i.bakirov 2019-02-04 17:19:52 UTC 
After system switch from 11-p8 to 12 nested PPTP & L2TP tunnels based on MPD5 does not work.

Got this error:
kernel: ng0: if_output recursively called too many (2)

After analyzing commits, found that for GIF, GRE and ME interfaces tunnel nesting limit check introduced and limit can be set by sysctl net.link.gif.max_nesting (man if_gif(4)):
https://svnweb.freebsd.org/base?view=revision&revision=336131

For the netgraph based tunnel nesting limit is checked against 1 and this limit can not be set by systcl:
https://svnweb.freebsd.org/base?view=revision&revision=337278
Comment 1 Andrey V. Elsukov freebsd_committer freebsd_triage 2019-02-06 17:56:29 UTC 
Mentioned changes seems do not change the behavior. The previous limit in the ng_iface node was 1. But I'm not very familiar with this code. Gleb can you take a look?
Comment 2 Andrey V. Elsukov freebsd_committer freebsd_triage 2019-02-06 18:15:47 UTC 
I think I see what happened. The previous code in the ng_iface did not count number of tags, it only could fail when ifnet pointer was the same. So, it doesn't fully match the behavior that if_tunnel_check_nesting() has.
Comment 3 Gleb Smirnoff freebsd_committer freebsd_triage 2019-02-07 03:19:05 UTC 
Created attachment 201808 [details]
suggested patch

Hi!

Can you please test this patch and confirm that desired behavior is achieved?
Comment 4 i.bakirov 2019-02-07 08:52:41 UTC 
Asked initial problem reporter to check out patch.
Comment 5 i.bakirov 2019-02-08 06:09:21 UTC 
Andrey and Gleb thanks for the suggested patch. Patch confirmed by Слава Трофимов to be working!

All credits/thanks to Слава Трофимов and to others participated on this topic discussion: https://www.opennet.ru/openforum/vsluhforumID1/97363.html
Comment 6 commit-hook freebsd_committer freebsd_triage 2019-02-08 06:20:02 UTC 
A commit references this bug:

Author: glebius
Date: Fri Feb  8 06:19:29 UTC 2019
New revision: 343895
URL: https://svnweb.freebsd.org/changeset/base/343895

Log:
  Allow some nesting of ng_iface(4) interfaces and add a configuration knob.

  PR:		235500
  MFC after:	1 week

Changes:
  head/share/man/man4/ng_iface.4
  head/sys/netgraph/ng_iface.c
Comment 7 commit-hook freebsd_committer freebsd_triage 2019-02-15 00:30:18 UTC 
A commit references this bug:

Author: glebius
Date: Fri Feb 15 00:29:45 UTC 2019
New revision: 344139
URL: https://svnweb.freebsd.org/changeset/base/344139

Log:
  Merge r343895:
    Allow some nesting of ng_iface(4) interfaces and add a configuration knob.

  PR:		235500

Changes:
_U  stable/12/
  stable/12/share/man/man4/ng_iface.4
  stable/12/sys/netgraph/ng_iface.c