[PLUG] DBus

[Rich Freeman <r-plug@thefreemanclan.net>]

Does anybody in PLUG have a strong knowledge of DBus?

With its move into the kernel and heavy reliance by systemd and other
key system daemons I'd think that this would be a GREAT topic for a
talk.

I'd really prefer that this talk be given by somebody who actually
knows what they're talking about.  However, I'm interested enough in
it that if nobody steps up I might just start studying it more myself
and maybe try to do a talk over the summer.

I'm pretty sure that systemd utilities like systemctl and journalctl
and such are really just wrappers around DBus requests to
systemd/journald/etc.  That is why when I ran machinectl as a
non-privileged user during my talk I got an error message.  All
machinectl does is make a request, and then it is up to things like
PolicyKit and such to tell systemd to honor the request or not.  This
also means that with proper tuning you could probably allow non-root
users to make specific DBus requests to various daemons.  This was one
of the drivers for moving it into the kernel - the kernel is in the
best position to guarantee that when a DBus request comes in from
"root" on "tty1" that it really is coming from root on tty1, and so
on.  Incidentally, this is also one of the arguments for having
logging more integrated with service management - when the journal
says that the log entry came from postfix, you know that it really
came from postfix or one of its children.

--
Rich
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