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Introduction

With the introduction of the CS IAM feature in 4.4 release, there are a few changes to be aware of and followed while adding a new API and any service layer access control.

In this document we will maintain any API coding conventions, annotations, standards to be followed w.r.t  IAM checks.

References

How to set API permissions

What happens to commands.properties and @APICommand(authorized=) annotation after adding the IAM feature? No changes, they work as they used to.

  • Use the commands.properties and 'authorized' mechanism to specify who can invoke the API.
  • IAM service will read these permissions from both inputs and load it to the DB, So any change to commands.properties file should take effect on a restart as it used to be.
  • However remember both of them allow setting permissions for CloudStack's default policies only. (User/Resource Domain Admin/Domain Admins/Root Admin Policy)
  • Custom Policies: While IAM feature will support creating custom policies, the permissions for these custom policies need to be set separately using the IAM APIs

IAM for the API and Service layer (entity permissions)

 

Following guidelines should be followed while adding a new API to CloudStack inorder to ensure correct access control is weaved into the logic for all the entities involved.

Guidelines for adding a new CUD* API

(create/update/delete)

 

With IAM, one should use the correct AccessType in the @ACL annotation or at service layer to specify what kind of access is needed for the entity while invoking this API.

AccessType
  • Until 4.4, CloudStack did not distinguish between a read-only access Vs read-and-use access Vs operate access. 
  • CloudStack access control layer always checked if the caller is owner of the entity and granted all types of access based on that. 
  • With IAM feature following are the types of entity access one can specify:
    1. ListEntry  (read only access)
    2. UseEntry  (read and use access)
    3. OperateEntry (operate/execute access)

Example: A domainAdmin registers a template T and allows a regular user of the domain to launch a VM using that template.

Entity: TemplateT
Principal1:  domainAdmin, Access allowed: OperateEntry   (operate access since he can invoke delete/updatepermissions operations on the template)
Principal2: normal domain user, Access allowed: UseEntry  (the user can only list the template and use it for launching VM)

IAM At API layer: use @ACL

  • For the primary ID API parameter which identifies the entity being operated on, put annotation  @ACL(accessType = AccessType.OperateEntry)
  • For all other entities putting @ACL or @ACL(accessType = AccessType.UseEntry) should suffice. This will make sure the caller can 'list and use' the entity for the desired operation.
  • By default the annotation uses AccessType.UseEntry

Typically for:

  • create APIs : one needs @ACL(accessType = AccessType.UseEntry) on all the entities required to be used for creating the desired new entity
  • update/delete APIs: These modify or operate on an entity and change its state. @ACL(accessType = AccessType.OperateEntry) should be used in these APIs on the parameter that identifies the main entity being modified.

 

Example:

  • DeployVMCmd 
    • This is a create API
    • Add @ACL(accessType = AccessType.UseEntry access for all entities like template, network
  • Start/Stop/Reboot/Destroy/AttachXXXTOVM :
    • These are the update/delete APIs
    •  Add @ACL(accessType = AccessType.OperateEntry) access for VM ID parameter that identifies the VM entity being operated on

IAM At Service Layer:

CS Service layer logic uses  "accountManager.checkAccess" to invoke the SecurityCheckers to do access control. Instead, one should try to use @ACL annotation on the API parameters that have to be checked for access.

This will help to funnel the calls to the IAM Service at API layer itself without invoking any service layer logic.

 

But in some cases, you may need to still add such checks at Service layer. (example, when the entity you want to check access for is not exposed in the API cmd as a parameter)

  • Use the correct accessType parameter in these calls.
  • accessType = null equals AccessType.UseEntry by default and will check for a read-and-use access.
  • If you want to make sure only the owner or the granted accounts can operate(start/stop/reboot/destroy/attachXXX/addXXX) on an entity, use AccessType.OperateEntry instead.
  • If the API layer already uses @ACL with accesstype specified on some entities, there is no need to do access checks at Service layer again.
  • Put the access control either in the API cmd OR in your Service/Manager Implementation.

 

Guidelines for adding a new R* API

(listXXX commands)

 

 

 

 

 

 

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