[apparmor] dbus/pair address rule encoding

[Tyler Hicks]

On 2013-05-09 14:04:20, Seth Arnold wrote:
> On Thu, May 09, 2013 at 01:45:04PM -0700, Tyler Hicks wrote:
> > I think that we're mostly ok. We just need to think about it a little
> > differently. Here's the current syntax:
> > 
> > DBUS RULE = [ 'audit' ] [ 'deny' ] 'dbus' [ DBUS BUS ] [ ( DBUS LOCAL CONDITIONS | -> DBUS REMOTE CONDITIONS ) ]  [ DBUS ACCESS EXPRESSION ]
> > 
> 
> [ ... ]
> 
> > 
> > For example, to profile an application that acquires the well known name
> > com.example.service on the session bus and exports the ExampleMethod
> > method on the com.example.service interface, this would be what the dbus
> > portion of the service's profile looks like:
> > 
> >   dbus bus=session -> name=org.freedesktop.DBus path=/org/freedesktop/DBus interface=org.freedesktop.DBus send,
> >   dbus bus=session name=com.example.service acquire,
> >   dbus bus=session -> name=com.example.service path=/com/example/service interface=com.example.service member=ExampleMethod receive,
> > 
> 
> [ ... ]
> 
> > 
> > The third rule allows messages to be sent from *any* connection to the
> > service. Note that the even though com.example.service is owned by the
> > application that we're profiling, it's address is specified in the
> > <DBUS REMOTE CONDITIONS>. I think that's acceptable.
> 
> If the application acquired the interface and the application exports
> the method, why are those details placed on the 'peer' side of the
> arrow? I'm very confused here. :)

I agree that if you think of it in terms of 'peer', it doesn't make
sense.

For the arrow to make sense, we'd need to think of the right side of the
arrow as the destination of the message.

Take this rule for example:

  dbus bus=session -> name=com.example.service path=/com/example/service interface=com.example.service receive,

If we adjust our thinking a little it could mean, "a message that flows
FROM anywhere TO com.example.service can be received under the
current profile."

Tyler

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