Re: NM attempts connecting to nonexistent AP

[Dan Williams <dcbw redhat com>]

On Thu, 2015-12-24 at 17:38 -0600, Robby Workman wrote:
> On Thu, 11 Sep 2014 16:47:45 -0500
> Dan Williams <dcbw redhat com> wrote:
>
> > On Wed, 2014-09-10 at 22:53 -0500, Robby Workman wrote:
> > > Summary: when resuming from sleep, NM attempts to connect to an
> > > AP
> > > that no longer exists.  
> >
> > Hmm, odd.  You could turn on debugging and enable the "wifi_scan"
> > log
> > domain to see what's going on at resume time.  NM should be
> > throwing
> > away the scan list on resume and requesting a new scan from
> > wpa_supplicant, and all that should be reflected in the debug logs
> > when the wifi_scan domain is enabled.
>
>
> I filed this away to debug later, and "later" never arrived :/
>
> However, a user on LQ reported some dbus messages getting rejected on
> suspend:
>
> http://www.linuxquestions.org/questions/slackware-14/current-xfce4-po
> wer-manager-error-messages-on-suspend-resume-4175562257/#post5468365
>
> I'm seeing those here too:
>
> Dec 22 17:13:54 liberty dbus[1162]: [system] Rejected send message, 4
> matched \
>   rules; type="method_call", sender=":1.66" (uid=1000 pid=5803 \
>   comm="xfce4-power-manager ")
> interface="org.freedesktop.NetworkManager" \
>   member="Sleep" error name="(unset)" requested_reply="0" \
>   destination="org.freedesktop.NetworkManager" \
>   (uid=0 pid=1198 comm="/usr/sbin/NetworkManager ")
> Dec 22 17:16:41 liberty dbus[1162]: [system] Rejected send message, 4
> matched \
>   rules; type="method_call", sender=":1.66" (uid=1000 pid=5803 \
>   comm="xfce4-power-manager ")
> interface="org.freedesktop.NetworkManager" \
>   member="Sleep" error name="(unset)" requested_reply="0" \
>   destination="org.freedesktop.NetworkManager" \
>   (uid=0 pid=1198 comm="/usr/sbin/NetworkManager ")
>
> I notice that /etc/dbus
> -1/system.d/org.freedesktop.NetworkManager.conf says
> that they are root-only functions:
>
>   <!-- Root-only functions -->
>   <deny send_interface="org.freedesktop.NetworkManager"
> send_member="SetLogging"/>
>   <deny send_interface="org.freedesktop.NetworkManager"
> send_member="Sleep"/>
>
> and if I change it to allow one of my groups, then I no longer get
> those 
> logged Rejected messages.
>
> So... three questions here:
>
> 1) is this possibly related to my original problem report? I'm not
> able to
> test it just yet and won't be until I go back to work after the
> holidays.

If NM doesn't get the Sleep() method call when suspending, then yes it
won't clear the scan list and when the device is moved it may still see
old APs for a bit.

> 2) is xfce4-power-manager supposed to be calling that Sleep here?
> There is
> a configure option to --(en|dis)able-network-manager that is
> currently
> enabled in our build, but if it should be disabled, we can fix that.

Whatever tells the kernel to suspend the system should be calling
Sleep() on NM.  In my experience that's always been a root process
(like upower or systemd or pm-utils), and since Sleep() has the
capability to drastically change you networking, it was restricted to
root-only.  I'm a bit surprised that xfce4-power-manager is trying to
call Sleep() as the normal user, not root, since suspending the machine
takes root privileges anyway.

> 3) what is the expectation for that Sleep? What is supposed to call
> it (or 
> is *anything* supposed to be calling it from outside NM)?

Whatever tells the kernel to suspend (which requires root) should also
be telling NM to Sleep() (and wake).

Dan