Re: [Utopia] is gmv only ment for mountable stuff?

[Joe Shaw <joeshaw novell com>]

Hi,

On Wed, 2004-08-04 at 04:09 +0200, David Zeuthen wrote:
> 1. Factor out the callout code from hald and produce a daemon, let's
> call it hal-policy-manager, that listens for messages from hald on the
> system bus. Specifically, we would have an instance on the system-level
> 
>  # hal-policy-manager --callout-dir /etc/hal
> 
> and for each session
> 
>  $ hal-policy-manager --callout-dir $HOME:.hal/callouts:/etc/hal/session

How would the session one be invoked by the correct user, short of
having a daemon listening for some sort of notification?

> An added benefit would be that we could run hald with a lot less
> privileges (hald would still start up as root, but we would drop of lot
> of POSIX caps as the very first thing). This is actually enough reason
> for me to factor out the callout code :-)

If hald drops its privileges, then lifecycle issues worry me.
hal-policy-manager would have to be a separate daemon because otherwise
caps would be inherited and you don't want to limit the callouts.  If it
crashed, there wouldn't be any way to bring it back without restarting
hald.  And then you have to write some protocol to communicate between
the two.  Ugh. :)

And all this is assuming the OS supported capabilities, which I think
only Linux does.  I suspect a lot of people would prefer to use SELinux
or whatever the flavor of the month is.

> 2. Write a generic policy manager engine, like the one you described,
> that activates daemons when stuff happens, e.g. when HAL adds a new
> storage device. I'm not sure whether this is easy - it seems you would
> have to "stop" or at least "cache" traffic such that the daemon you're
> booting isn't missing any interesting messages.

I'm not sure how much you'd really need to invoke daemons as much as
one-off callouts.  g-v-m for example wouldn't need to be a daemon
anymore.  It could just check the type of media and execute mount and
whatever program is to be launched.  Hell, we could replace it with a
shell script. :)

> However, note that some daemons will have to do some stuff when the
> session starts and stops anyway. For example, g-v-m should mount all
> volumes when the session starts and unmount them when the session ends
> like discussed here (it's not yet implemented though) and I wouldn't be
> surprised if most "interesting" policy daemons would need to do the
> same?

Good point.  The generic policy engine could probably handle this as
it'd be started as a part of the session.

Joe