Yes, the problem starts with the apparmour protection system not knowing
it should be allowed serial port access. However, I tried to edit
/etc/apparmor.d/tunables/ntpd to change the line to:
@{NTPD_DEVICE}=/dev/ttyS0
then restarted /etc/init.d/apparmor but that did to help, however,
adding this to the /etc/apparmor.d/usr.sbin.ntpd file:
/dev/ttyS0 rw,
then restarting /etc/init.d/apparmor did work.
So first question is what is the correct entry in
/etc/apparmor.d/tunables/ntpd needed to do it the preferred way?
The next observation is that rendering the serial port theoretically
unusable by:
sudo chmod 000 /dev/ttyS0
Produced similar, but not quite identical results:
Jun 21 12:36:08 pscpc ntpd[8089]: ntpd 4.2....@1.1612-o Fri Apr 9 00:28:40 UTC
2010 (1)
Jun 21 12:36:08 pscpc ntpd[8090]: precision = 1.000 usec
Jun 21 12:36:08 pscpc ntpd[8090]: ntp_io: estimated max descriptors: 1024,
initial socket boundary: 16
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #0 wildcard,
0.0.0.0#123 Disabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #1 wildcard, ::#123
Disabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #2 vmnet8,
fe80::250:56ff:fec0:8#123 Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #3 lo, ::1#123 Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #4 vmnet1,
fe80::250:56ff:fec0:1#123 Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #5 eth0,
fe80::213:20ff:fecb:72d6#123 Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #6 lo, 127.0.0.1#123
Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #7 eth0,
134.36.22.24#123 Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #8 vmnet1,
192.168.227.1#123 Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: Listening on interface #9 vmnet8,
192.168.154.1#123 Enabled
Jun 21 12:36:08 pscpc ntpd[8090]: kernel time sync status 2040
Jun 21 12:36:08 pscpc ntpd[8090]: frequency initialized -1.256 PPM from
/var/lib/ntp/ntp.drift
Jun 21 12:36:08 pscpc ntpd[8090]: refclock_open /dev/gps0: Permission denied
Jun 21 12:36:08 pscpc kernel: [ 4642.663943] type=1503
audit(1277120168.659:117): operation="capable" pid=8090 parent=1
profile="/usr/sbin/ntpd" name="dac_override"
Jun 21 12:36:08 pscpc kernel: [ 4642.664223] ntpd[8090]: segfault at 0 ip
0043e7bc sp bfa3f650 error 4 in libc-2.11.1.so[40e000+153000]
But now the oddest part, if I stop apparmor there is no problem, and
stranger still it is *working* to read the serial port that is
apparently unusable for read or write:
p...@pscpc:~$ ls -l /dev/ttyS0
c--------- 1 root dialout 4, 64 2010-06-21 12:41 /dev/ttyS0
Why/how it is overriding the permission setting is not clear.
My final question is how do I get a stack trace?
I have seen instructions on how to use gdb, but if I try to run the ntpd
program with gdb using the same command line as the running daemon is
(from ps -Af) it says the program terminated normally, which is clearly
not the case as it still shows the segmentation happening fault in the
syslog file.
--
ntpd sementation fault using NMEA driver
https://bugs.launchpad.net/bugs/596010
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