[Kimchi-devel] [RFC] Authorization enhancement

[Frank Novak]

Sounds reasonable by me....
Is it done yet? :-)


Cheers,
Frank

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Frank Novak  ( 诺帆 nuò、fān )
STSM, SCEM Open Hypervisor
IBM Linux Technology Center
US:  fnovak at us.ibm.com  ;  Notes:   Frank Novak/Watson/IBM @IBMUS
cell : 919-671-7966
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Adam King rak at linux.vnet.ibm.com
Tue Jan 21 20:38:51 EST 2014
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The proposal is over ambitious in some areas, under ambitious in others.
I'd suggest the following:

*Assumptions:*
The first objective of introducing authorization into Kimchi is to allow
an admin to partition defined VMs for independent, secure use by
different users.

*Scenario:
*Frank is the manager of a team consisting of developers and testers
with a clear separation of responsibility. He already has groups created
on his linux host with user id membership organized by the user's
function. Frank needs to create some VMs for his teams to use. He is the
sole root user on the host.
He wants the developers to be able to manage their VMs' lifecycle, but
not to have permission to increase their VMs resource allocation.
Developers always want as much memory as they can get away with:-)
He wants the testers to have permission to edit the resource allocation
of their VMs. The software needs to be verified with different hardware
configurations, and he doesn't want to have to make every edit for his
testers each time they need to validate a new scenario.
*Resolution:*
Frank creates his VMs.
Those he has created for use by his developers, he assigns the user role
to the development group for each of the VMs granting all his developers
permission to see and manage the life cycle of the VMs
Those he has created for use by his testers, he assigns the admin role
to the test group for each of the VMs granting all his testers
permission to see and take all actions to the VMs


*User Design goals*
An existing system user will only see the resources and actions the user
is authorized to use
An existing system sudo user will see and be able to act on all resources
Actions on a given resource can be restricted with more than binary
granularity. Some authorized users may have more privilege on a resource
than others. ie Some authorized users may be able to edit a VMs resource
definition, while others can only manipulate its life cycle

*System Design Goals*
No new prerequisites are required to be installed or managed. i.e. No
database prerequisite
No new user repository is required beyond what the host system is
configured to use. PAM
The authorization scheme will work with read only user repositories.
Authorization information will be portable. ie. If a VM is moved from
one kimchi host to another, the new host is immediately aware of the
security constraints.
The system is secure. A user will not be able discover the REST API and
invoke actions directly without authorization.
Kimchi managed resources can still be managed by other KVM tools, and
returned to Kimchi without loss of function.
Kimchi 1.2 authorization design is extensible to cover arbitrarily fine
grained constraints


*Kimchi 1.2 Proposal*
Users in the sudo (admin) group would continue having full access to all
Kimchi functions.
Users not in the sudo (admin) group would only have access to VMs that
they are authorized to use.
A VM user could have one of two roles on a given VM
         admin - user has access to all VM actions on the individual VM
         user - user has access to power on, power off, reboot,
snapshot, VNC/Spice as appropriate on the individual VM

Group/role mapping will be stored in the <metadata> element of the VM
Domain XML. If the VM is migrated to a new host, the metadata will go
with it.

*Algorithm*
Login:
     If the user is a member of the sudo (admin) group
         grant all permissions and render the full Kimchi UI as today
     else
         enumerate all the groups the user is a member of, including
groups of groups recursively
         for each VM determine the highest role available to the user by
the various groups he is a member of
         render the kimchi frame with only a list of the authorized VMs,
each with the appropriate actions
         If none, render the empty list


*Kimchi 1.2+ Extensibilty
*How can the 1.2 proposal be extended in future Kimchi versions as needed?
*    Resource **
*        Other resources (network, storage) can use the same group/role
authorization concept, relying on similar libvirt metadata for storage.
Storage for the authorization mapping would have to be elsewhere for any
resource libvirt has not defined metadata on.
*    Admin granularity*
         Additional roles can be introduced to allow some admins control
over network while others control storage pools and volumes. Storage for
these administration scoped roles would have to be defined and
replicated for future cluster support.
*Role granularity*
         Additional roles can be introduced beyond admin and user to
allow more differentiation in what actions a specific group of users can
access including custom administrator defined roles

--
Adam King <rak at linux.vnet.ibm.com>
IBM CSI
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