Re: Accessing NetworkManager from a daemon

[Dan Williams <dcbw redhat com>]

On Wed, 2014-08-27 at 09:04 +0200, Thomas Haller wrote:
> On Wed, 2014-08-27 at 16:40 +1000, Stuart Longland wrote:
> > Hi all,
> > On 25/08/14 13:36, Stuart Longland wrote:
> > > Today I thought I'd roll this into my company's administration panel
> > > software which is built on Django and runs within Apache under mod_wsgi.
> > >
> > > When I try to get the settings of an existing connection (via
> > > GetSettings), I get the following:
> > >
> > > org.freedesktop.NetworkManager.Settings.PermissionDenied: No session
> > > found for uid 33 (unknown)
> >
> > I've heard nothing, so I can only assume I haven't provided some detail.
> >  Sadly, searching for the above error leads me right back to this post,
> > thanks to the wonder that is the dreaded Google echo.
> >
> > My code is based on the python-dbus examples and is running under the
> > Apache www-data user.  Calling GetSettings on a settings object seems to
> > trigger this.
> >
> > The following are the package versions I am using:
> > > stuartl sjl-lxc-debian:~$ dpkg -l python-dbus
> > > Desired=Unknown/Install/Remove/Purge/Hold
> > > | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
> > > |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
> > > ||/ Name                    Version          Architecture     Description
> > > +++-=======================-================-================-===================================================
> > > ii  python-dbus             1.2.0-2+b3       i386             simple interprocess messaging system 
> > > (Python interf
> > > stuartl sjl-lxc-debian:~$ dpkg -l network-manager
> > > Desired=Unknown/Install/Remove/Purge/Hold
> > > | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
> > > |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
> > > ||/ Name                    Version          Architecture     Description
> > > +++-=======================-================-================-===================================================
> > > ii  network-manager         0.9.10.0-1.1     i386             network management framework (daemon and 
> > > userspace 
> >
> > The error message in my previous post, is what I get told.  Research
> > seems to suggest it's a polkit issue, in that the www-data user doesn't
> > appear as a logged-in user.
>
>
> This is not a question for polkit, but for session tracking.
>
> You can workaround this by configuring NM with
>   --with-session-tracking=no
>
> I don't know how to achieve this without recompiling NM, I think
> it should be possible too(?). Let's see what dcbw has to say about it
> (put him on CC).

At the moment, session tracking means you can't easily talk to NM if you
are (a) not root and (b) don't have a session via ConsoleKit or Polkit.
That's something we want to change, and that's being tracked and
actively worked on in this bug:

https://bugzilla.gnome.org/show_bug.cgi?id=686997

But like Thomas says, you can get around this for now if you rebuild NM
with --with-session-tracking=no.

Dan

> > This is going to be a headless appliance, there will be *no* "logged in"
> > user in the traditional sense, rather someone will be logging in via a
> > web UI to change settings, including the network configuration.
> >
> > Thus, I need to either disable the polkit integration, or convince it
> > that it's okay for www-data to talk to NetworkManager.
> >
> > Is there someone who can provide some pointers as to where to go or
> > shall I have to dump NetworkManager for something else?
> >
> > Regards,
>
>
> Thomas