Unfortunately the fix doesn't work and Ubuntu 19.10 with ppp
2.4.7-2+4.1ubuntu4.1 is still affected. I've added a bunch of
logger -t 0000usepeerdns -- doing stuff
commands to /etc/ppp/ip-up.d/0000usepeerdns and /etc/ppp/ip-
down.d/0000usepeerdns.
Here's what I see when /etc/resolv.conf is a symlink to
/run/systemd/resolve/stub-resolv.conf (which is the standard Ubuntu
configuration) and /run/systemd/resolve/stub-resolv.conf is owned by
systemd-resolve:systemd-resolve:
$ journalctl -b SYSLOG_IDENTIFIER=0000usepeerdns -f
kov. 18 22:16:44 blynas 0000usepeerdns[29590]: running
/etc/ppp/ip-up.d/0000usepeerdns ppp0 0 10.46.37.85 192.0.2.1
7c4ea6b5-3f8b-4874-a81a-c4712fa17787
kov. 18 22:16:44 blynas 0000usepeerdns[29592]: the real resolv.conf is
/run/systemd/resolve/stub-resolv.conf
kov. 18 22:16:44 blynas 0000usepeerdns[29595]: created
/run/systemd/resolve/stub-resolv.conf.tmp
kov. 18 22:16:44 blynas 0000usepeerdns[29597]: -rw-r--r-- 1 systemd-resolve
systemd-resolve 719 Mar 18 22:16 /run/systemd/resolve/stub-resolv.conf
-rw-r--r-- 1 root
root 749 Mar 18 22:16 /run/systemd/resolve/stub-resolv.conf.tmp
This indicates that the script aborted early due to the `#!/bin/sh -e` shebang
line, as I had more logging statements. The failing command must've been the
cp -a.
Disconnecting produces
kov. 18 22:16:49 blynas 0000usepeerdns[29785]: running
/etc/ppp/ip-down.d/0000usepeerdns ppp0 0 10.46.37.85 192.0.2.1
7c4ea6b5-3f8b-4874-a81a-c4712fa17787
kov. 18 22:16:49 blynas 0000usepeerdns[29791]: -rw-r--r-- 1 systemd-resolve
systemd-resolve 719 Mar 18 22:16 /run/systemd/resolve/stub-resolv.conf
-rw------- 1 root
root 719 Mar 18 22:16
/run/systemd/resolve/stub-resolv.conf.pppd-backup.ppp0
kov. 18 22:16:49 blynas 0000usepeerdns[29797]: moved
/run/systemd/resolve/stub-resolv.conf.pppd-backup.ppp0 to
/run/systemd/resolve/stub-resolv.conf
kov. 18 22:16:49 blynas 0000usepeerdns[29803]: -rw------- 1 root root 719 Mar
18 22:16 /run/systemd/resolve/stub-resolv.conf
kov. 18 22:16:49 blynas 0000usepeerdns[29805]: all is well!
Now if I apply a manual fix of the form
sudo chmod a+r /etc/resolv.conf
and then connect to the VPN again, I'll see that the script runs
successfully to the end
kov. 18 22:18:17 blynas 0000usepeerdns[30617]: running
/etc/ppp/ip-up.d/0000usepeerdns ppp0 0 10.46.37.85 192.0.2.1
7c4ea6b5-3f8b-4874-a81a-c4712fa17787
kov. 18 22:18:17 blynas 0000usepeerdns[30619]: the real resolv.conf is
/run/systemd/resolve/stub-resolv.conf
kov. 18 22:18:17 blynas 0000usepeerdns[30622]: created
/run/systemd/resolve/stub-resolv.conf.tmp
kov. 18 22:18:17 blynas 0000usepeerdns[30627]: -rw-r--r-- 1 root root 719 Mar
18 22:16 /run/systemd/resolve/stub-resolv.conf
-rw-r--r-- 1 root root 749 Mar
18 22:18 /run/systemd/resolve/stub-resolv.conf.tmp
kov. 18 22:18:17 blynas 0000usepeerdns[30636]: backed up
/run/systemd/resolve/stub-resolv.conf to
/run/systemd/resolve/stub-resolv.conf.pppd-backup.ppp0
kov. 18 22:18:17 blynas 0000usepeerdns[30638]: -rw-r--r-- 1 root root 719 Mar
18 22:16 /run/systemd/resolve/stub-resolv.conf
-rw-r--r-- 1 root root 719 Mar
18 22:16 /run/systemd/resolve/stub-resolv.conf.pppd-backup.ppp0
-rw-r--r-- 1 root root 749 Mar
18 22:18 /run/systemd/resolve/stub-resolv.conf.tmp
kov. 18 22:18:17 blynas 0000usepeerdns[30640]: moved
/run/systemd/resolve/stub-resolv.conf.tmp to
/run/systemd/resolve/stub-resolv.conf
kov. 18 22:18:17 blynas 0000usepeerdns[30643]: -rw-r--r-- 1 systemd-resolve
systemd-resolve 719 Mar 18 22:18 /run/systemd/resolve/stub-resolv.conf
-rw-r--r-- 1 root
root 719 Mar 18 22:16
/run/systemd/resolve/stub-resolv.conf.pppd-backup.ppp0
kov. 18 22:18:17 blynas 0000usepeerdns[30644]: all is well!
and when I disconnect, the bug is no longer showing up:
kov. 18 22:18:38 blynas 0000usepeerdns[30885]: running
/etc/ppp/ip-down.d/0000usepeerdns ppp0 0 10.46.37.85 192.0.2.1
7c4ea6b5-3f8b-4874-a81a-c4712fa17787
kov. 18 22:18:38 blynas 0000usepeerdns[30900]: -rw-r--r-- 1 systemd-resolve
systemd-resolve 719 Mar 18 22:18 /run/systemd/resolve/stub-resolv.conf
-rw-r--r-- 1 root
root 719 Mar 18 22:16
/run/systemd/resolve/stub-resolv.conf.pppd-backup.ppp0
kov. 18 22:18:38 blynas 0000usepeerdns[30905]: moved
/run/systemd/resolve/stub-resolv.conf.pppd-backup.ppp0 to
/run/systemd/resolve/stub-resolv.conf
kov. 18 22:18:38 blynas 0000usepeerdns[30907]: -rw-r--r-- 1 root root 719 Mar
18 22:16 /run/systemd/resolve/stub-resolv.conf
kov. 18 22:18:38 blynas 0000usepeerdns[30908]: all is well!
The only difference is the ownership of /run/systemd/resolve/stub-resolv.conf.
Somehow the cp -a fails to change the ownership of the backup file from
root:root to systemd-resolve:systemd-resolve.
What could prevent a script running as root from chowning a file?
AppArmor?
Also note that the "running under NetworkManager" check in /etc/ppp/ip-
up.d/0000usepeerdns never fires because $6 is always blank AFAICS.
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https://bugs.launchpad.net/bugs/1778946
Title:
No dns resolution after closing a vpn/pptp connection
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