Bug #2403

Charon doesn't detect interface up event of a renamed interface (and charon.interfaces_use is set)

Added by Luka Logar almost 5 years ago. Updated almost 5 years ago.

Target version:
Start date:
Due date:
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I am using strongswan on a linux host that is using pppoe on a wan interface (interface name is pppoe-wan). I have also set

in charon.conf. If the pppoe connection is dropped for one reason or another, charon correctly detects it and deactivates and deletes interface and its address:
2017-08-12T11:52:01.384013+02:00 swan pppd[14026]: Terminating on signal 15
2017-08-12T11:52:01.384155+02:00 swan pppd[14026]: Connect time 1238.5 minutes.
2017-08-12T11:52:01.384204+02:00 swan pppd[14026]: Sent 3975626 bytes, received 1742734 bytes.
2017-08-12T11:52:01.385009+02:00 swan charon: 01[KNL] interface pppoe-wan deactivated
2017-08-12T11:52:01.391010+02:00 swan charon: 08[KNL] disappeared from pppoe-wan
2017-08-12T11:52:01.398327+02:00 swan pppd[14026]: Connection terminated.
2017-08-12T11:52:01.399265+02:00 swan charon: 13[KNL] interface pppoe-wan deleted
2017-08-12T11:52:01.445182+02:00 swan pppd[14026]: Sent PADT
2017-08-12T11:52:01.465524+02:00 swan pppd[14026]: Exit.

However later, when the connection is reestablished charon doesn't detect it and IKE communication is not reestablised:
2017-08-12T11:52:39.536333+02:00 swan pppd[3315]: Plugin loaded.
2017-08-12T11:52:39.536550+02:00 swan pppd[3315]: RP-PPPoE plugin version 3.8p compiled against pppd 2.4.7
2017-08-12T11:52:39.653610+02:00 swan pppd[3315]: pppd 2.4.7 started by root, uid 0
2017-08-12T11:52:44.696467+02:00 swan pppd[3315]: PPP session is 3
2017-08-12T11:52:44.696552+02:00 swan pppd[3315]: Connected to 6c:3b:7e:62:a9:dc via interface eth0
2017-08-12T11:52:44.714735+02:00 swan kernel: [79025.853112] pppoe-wan: renamed from ppp0
2017-08-12T11:52:44.745002+02:00 swan pppd[3315]: Using interface pppoe-wan
2017-08-12T11:52:44.745224+02:00 swan pppd[3315]: Connect: pppoe-wan <--> eth0
2017-08-12T11:52:44.856800+02:00 swan pppd[3315]: CHAP authentication succeeded: Welcome.
2017-08-12T11:52:44.856867+02:00 swan pppd[3315]: CHAP authentication succeeded
2017-08-12T11:52:44.856913+02:00 swan pppd[3315]: peer from calling number 6C:3B:6B:62:A9:DC authorized
2017-08-12T11:52:44.884029+02:00 swan pppd[3315]: local  IP address
2017-08-12T11:52:44.884087+02:00 swan pppd[3315]: remote IP address

This happens because kernel_netlink first receives RTM_NEWLINK message for ppp0 interface and since it is not in a charon.interfaces_use list marks it as not usable. Later RTM_NEWLINK messages with a new/renamed name (pppoe-wan) are ignored as interface already exists in ifaces list (but is marked as not usable).

The solution is to set usable flag in each RTM_NEWLINK message processing:

--- a/src/libcharon/plugins/kernel_netlink/kernel_netlink_net.c
+++ b/src/libcharon/plugins/kernel_netlink/kernel_netlink_net.c
@@ -1192,6 +1192,8 @@
             strncpy(entry->ifname, name, IFNAMSIZ);
             entry->ifname[IFNAMSIZ-1] = '\0';
+            if (!entry->usable)
+                entry->usable = charon->kernel->is_interface_usable(charon->kernel, name);
             if (event && entry->usable)
                 if (!(entry->flags & IFF_UP) && (msg->ifi_flags & IFF_UP))

After applying the patch, charon correctly detects interface up event:
2017-08-12T22:23:24.662697+02:00 swan pppd[4022]: Plugin loaded.
2017-08-12T22:23:24.662928+02:00 swan pppd[4022]: RP-PPPoE plugin version 3.8p compiled against pppd 2.4.7
2017-08-12T22:23:24.768112+02:00 swan pppd[4022]: pppd 2.4.7 started by root, uid 0
2017-08-12T22:23:29.796954+02:00 swan pppd[4022]: PPP session is 41
2017-08-12T22:23:29.797044+02:00 swan pppd[4022]: Connected to 6c:3b:7e:62:a9:dc via interface eth0
2017-08-12T22:23:29.819532+02:00 swan kernel: [  320.251407] pppoe-wan: renamed from ppp0
2017-08-12T22:23:29.850067+02:00 swan pppd[4022]: Using interface pppoe-wan
2017-08-12T22:23:29.850283+02:00 swan pppd[4022]: Connect: pppoe-wan <--> eth0
2017-08-12T22:23:29.958745+02:00 swan pppd[4022]: CHAP authentication succeeded: Welcome.
2017-08-12T22:23:29.958822+02:00 swan pppd[4022]: CHAP authentication succeeded
2017-08-12T22:23:29.958871+02:00 swan pppd[4022]: peer from calling number 6C:3B:6B:62:A9:DC authorized
2017-08-12T22:23:29.983180+02:00 swan pppd[4022]: local  IP address
2017-08-12T22:23:29.983641+02:00 swan pppd[4022]: remote IP address
2017-08-12T22:23:29.983699+02:00 swan charon: 13[KNL] appeared on pppoe-wan
2017-08-12T22:23:29.984411+02:00 swan charon: 12[KNL] disappeared from pppoe-wan
2017-08-12T22:23:29.984992+02:00 swan charon: 14[KNL] appeared on pppoe-wan
2017-08-12T22:23:29.985683+02:00 swan charon: 04[KNL] interface pppoe-wan activated

Associated revisions

Revision 062a34e7 (diff)
Added by Tobias Brunner almost 5 years ago

kernel-netlink: Set usable state whenever an interface appears

If an interface is renamed we already have an entry (based on the
ifindex) allocated but previously only set the usable state once
based on the original name.

Fixes #2403.


#1 Updated by Tobias Brunner almost 5 years ago

  • Category set to kernel-interface
  • Status changed from New to Feedback
  • Assignee set to Tobias Brunner
  • Target version set to 5.6.1

Thanks for the detailed report. Makes sense, I've pushed a fix to the 2403-kernel-netlink-iface-rename branch.

#2 Updated by Luka Logar almost 5 years ago

The patch is working as expected. I guess, you can mark this bug fixed/closed...

#3 Updated by Tobias Brunner almost 5 years ago

  • Status changed from Feedback to Closed
  • Resolution set to Fixed

Applied to master.

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