Re: [Libvir] PATCH: Updated patches for PolicyKit support
On Thu, Sep 20, 2007 at 05:46:07PM +0100, Daniel P. Berrange wrote:
On Thu, Sep 20, 2007 at 05:14:56PM +0100, Richard W.M. Jones wrote:
> I guess I'd be +1. What do the Solaris folks think?
>
> I wonder if issues of authentication and encryption can be separated out
> to allow a pluggable libvirt auth API?
This is an interesting question. Client authentication with PolicyKit is
out-of-band from the main libvirt<->client channel. ie, virt-manager has
to talk to DBus and say 'I want to gain credential org.libvirt.manage' and
then PolicyKit decides whether to allow it, require a password, require
the root password, etc. In my current impl, this has to be done prior to
connecting to the daemon. We have no API in libvirt for apps to be told
whether they need to authenticate, or gain credentials in some way. So
virt-manager just tries to use PolicyKit ahead of time, regardless since
it has no way to determine if the server will require it or not. I hate
to suggest it, but perhaps rather than re-purposing the existing UNIX
domain socket /var/run/libvirt/libvirt-sock or libvirt-sock-ro, I should
have added a distinct libvirt-sock-polkit ? That would at least give the
client app a way to test for existance ahead of time & thus decide if
it needs to request for credentials first.
To improve matter's we'd need a way for a client app to provide some form
of auth callback when opening a connection, and one or two new messages
on the wire to negotiate between client &server. This would probably require
a new virConnect variant taking a function pointer arg. But just what the
API contract will be is not all that straightforward & would want to be
extendable to work with stuff like SASL / GSSAPI.
We never really came to any conclusion on this last time....
http://www.mail-archive.com/libvir-list@redhat.com/msg00646.html
I still think it's a bit premature at this point to extract an auth API.
Yes this would be very neat to be able to provide a pluggable system, but
IMHO we are only starting to use remote operations, we didn't experience yet
with ACL-like for the various operation for domains, we don't have yet a
clear notion of identity, so I'm afraid any public API we would push at
this point in libvirt may not fit the real need of libvirt based management
tools I hope we will see in 1-2 years from now.
The work on PolicyKit will help definining the scope and limits of what
will be required in term of authentication, and as Dan pointed out when and
how we need to do so.
To me I +1 the PolicyKit patch, based on the fact that it doesn't require
to add and explicit API yet, that it goes in the right direction (getting
rid of the proxy for example), and the fact it's important to integrate
well with the Desktop when possible.
Note that I would not remove the proxy code right now, it might be better
to desactivate it if PolicyKit is not found, so we can push new libvirt
version to older Linuxes or systems without PolicyKit without breaking the
important functionality of being able to monitor as non-root.
Daniel
--
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard | virtualization library http://libvirt.org/
veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/