Allow Node Owners to Administer Nodes

https://storyboard.openstack.org/#!/story/2006506

This spec describes an update that allows a node owner to administer their node through the Ironic API without being able to administer the entire node cluster. This is accomplished by exposing owner node data in the REST API for policy checks.

Problem description

Ironic is not multi-tenant; anyone with API access to one node has access to all nodes. While nodes have an owner field, it is purely informational and not tied into any form of access control.

Bringing full multi-tenant support to Ironic would allow us to address the following user stories:

Standalone Ironic

As users of a shared data center, we would like to use Ironic to manage our hardware resources. Each work group should be able to control their own resources without having access to hardware resources owned by other groups.

Data center operator

As the operator of shared datacenter, I would like to delegate power control of baremetal hardware to the hardware owners using the Ironic API. By using the Ironic API instead of existing embedded management protocols (such as IPMI) I can maintain the simplicity of a shared management network while having granular control over who can access what hardware.

Proposed change

The Ironic API already has a way of controlling access to the REST API: a policy engine 0 that is used throughout the REST API. However, when the node controller uses the policy engine 1, it does so without passing in any information about the node being checked. Other services such as Nova 2 and Barbican 3 pass in additional information, and we propose doing the same. In summary, we would like to:

  • Assume that a node’s owner field is set to the id of a Keystone project. We refer to this project as the “node owner”.

  • Update the node controller so that policy checks also pass in information about the node, including the owner field.

  • Update Ironic’s default generated policy file to include an is_node_owner rule:

    • “is_node_owner”: “project_id:%(node.owner)s”

    The remainder of the policy file would stay the same, meaning that there is no change to default API access.

  • Create documentation explaining how to update an Ironic policy file to give API access to owners. For example:

    • “baremetal:node:set_power_state”: “rule:is_admin or rule:is_node_owner”

    Note that Nova grants API access in a similar manner 4.

This update is enough to control access for most API functions - except for list functions. For those, we propose the following:

  • Right now, the policy rule ‘baremetal:node:get’ is used for both get_all and get_one. We can add two new policy rules: baremetal:node:list_all for retrieving all nodes, and baremetal:node:list for retrieving nodes whose owner field matches the querying project.

  • Updating the REST API node list functions to first perform a policy check against baremetal:node:list_all. If it passes, then we return all nodes; otherwise we perform a policy check against baremetal:node:list. If that passes, then we return nodes filtered by the owner field against the project specified in the request context. These list functions already have the option of filtering by owner 5.

  • Updating the default generated policy file to set baremetal:node:list_all and baremetal:node:list to rule:baremetal:node:get to ensure backwards compatibility.

Allocation API changes

Allocation objects represent a request to find and reserve a suitable node, and as such should be available for non-administrator users. For this purpose we will introduce an owner field for allocations and start distinguishing two types of allocations:

unrestricted allocations

work the same as before. They can be created only by administrative users and can have any owner set. Creating them is governed by the existing policy baremetal:allocation:create.

restricted allocations

are created by non-administrative users and have owner matching the project ID of a creating user. Creating them will be governed by a new policy baremetal:allocation:create_restricted.

The two policies will be exclusive and work as follows:

  1. First, baremetal:allocation:create is checked. If it passes, then any value of owner is accepted. If no owner is provided, the field is left as None.

  2. If the first check does not pass, baremetal:allocation:create_restricted is checked. The owner field must match the project ID of the user or be empty (in which case it is set to the project ID of the user). HTTP Forbidden is returned if:

    1. The project ID of the user cannot be determined (i.e. restricted allocations do not work in the standalone mode).

    2. The requested non-empty owner does not match the project ID.

  3. Otherwise, creating the allocation fails.

Finally, when processing an allocation with non-empty owner, only nodes with a matching owner are considered.

Alternatives

One alternative is to perform these checks at the database API level. However that requires a new code pattern to be used on a large number of individual functions.

Data model impact

None

State Machine Impact

None

REST API impact

See details in “Proposed change” above.

Client (CLI) impact

None

“ironic” CLI

None

“openstack baremetal” CLI

None

RPC API impact

None

Driver API impact

None

Nova driver impact

None

Ramdisk impact

None

Security impact

This change allows functionality to be exposed to additional users. However this access is blocked off by default; it requires an update to the Oslo policy file, and can be adjusted as an administrator desires.

Other end user impact

None

Scalability impact

None

Performance Impact

None: although node data needs to be retrieved in order to pass that information into a policy check, the controller functions already fetch that information. 6

Other deployer impact

None

Developer impact

None

Implementation

Assignee(s)

Primary assignees: * tzumainn - tzumainn@redhat.com * larsks - lars@redhat.com

Other contributors: * dtantsur - dtantsur@redhat.com

Work Items

  • Update node controller.

  • Add documentation.

  • Write tests.

Dependencies

None

Testing

We will add unit tests and Tempest tests.

Upgrades and Backwards Compatibility

Existing Ironic installations that use the owner field for something other than a project ID will be minimally affected for two reasons:

  • If the owner field does not match a project ID (or is None), the proposed update to the policy file will not give any non-admin access to the Ironic API.

  • This change has no end-user impact if the policy file is not updated. An existing install can simply choose not to update their policy file.

Documentation Impact

We will include additional documentation describing the possible applications of using the node_owner policy roles.