Permissions

If you need to assign different permissions to personnel in your enterprise to access your OMS resources, Identity and Access Management (IAM) is a good choice for fine-grained permissions management. IAM provides identity authentication, permissions management, and access control, helping you securely access cloud resources. If your HUAWEI ID does not require IAM for permissions management, you can skip this section.

IAM is a free service. You only pay for the resources in your account.

With IAM, you can control access to specific Huawei Cloud resources. For example, if you want some software developers in your enterprise to use OMS resources but do not want them to delete OMS resources or perform any other high-risk operations, you can grant the permission to use OMS resources but not the permission to delete them.

IAM supports role/policy-based authorization and identity policy-based authorization.

The following table describes the differences between the two authorization models.

**Table 1** Differences between role/policy-based and identity policy-based authorization
Authorization Model	Core Relationship	Permissions	Authorization Method	Scenario
Role/Policy	User-permission-authorization scope	System-defined roles System-defined policies Custom policies	Assigning roles or policies to principals	To authorize a user, you need to add it to a user group first and then specify the scope of authorization. It is hard to provide fine-grained permissions control using authorization by user groups and a limited number of condition keys. This method is suitable for small- and medium-sized enterprises.
Identity policy	User-policy	System-defined policies Custom policies	Assigning identity policies to principals Attaching identity policies to principals	You can authorize a user by attaching an identity policy to it. User-specific authorization and a variety of key conditions allow for more fine-grained permissions control. However, this model can be hard to set up. It requires a certain amount of expertise and is suitable for medium- and large-sized enterprises.

Assume that you want to grant IAM users the permission to create ECSs in CN North-Beijing4 and OBS buckets in CN South-Guangzhou. With role/policy-based authorization, the administrator needs to create two custom policies and attach both to the IAM users. With identity policy-based authorization, the administrator only needs to create one custom policy, configure the condition key g:RequestedRegion for the policy, and attach the policy to the users or grant the users the access permissions to the specified regions. Identity policy-based authorization is more flexible than role/policy-based authorization.

Policies and actions in the two authorization models are not interoperable. You are advised to use the identity policy-based authorization model. For details about system-defined permissions in the two authorization models, see Role/Policy-based Authorization and Identity Policy-based Authorization.

For more information about IAM, see IAM Service Overview.

Role/Policy-based Authorization

OMS supports authorization with roles and policies. By default, new IAM users do not have permissions assigned. You need to add a user to one or more groups, and attach permissions policies or roles to these groups. Users inherit permissions from the groups to which they are added and can perform specified operations on cloud services based on the permissions.

OMS is a project-level service deployed in specific physical regions. When you set Scope to Region-specific projects and select the specified projects (for example, ap-southeast-2) in the specified regions (for example, AP-Bangkok), the users only have permissions for OMS resources in the selected projects. If you set Scope to All resources, the users have permissions for resources in all region-specific projects. When accessing OMS, the users need to switch to the authorized region.

Table 2 lists all the system-defined permissions for OMS. This role is dependent on other roles. Therefore, when assigning an OMS role to a user, you need to also assign the dependent roles to the user for the OMS permissions to take effect.

**Table 2** System-defined role supported by OMS
Role	Description	Dependency
OMS Administrator	Full permissions for OMS. Users granted these permissions can create, perform operations on, and view all OMS resources.	The Tenant Guest, Tenant Administrator, and OBS Administrator need to be assigned in the same project.

Identity Policy-based Authorization

OMS supports authorization with identity policies. Table 3 lists all the system-defined identity policies for OMS. System-defined identity policies and system-defined policies in the two authorization models are not interoperable.

**Table 3** System-defined identity policies
Identity Policy	Description	Type
OMSFullAccessPolicy	Administrator permissions for OMS. Users granted these permissions can create, perform operations on, and view all OMS resources.	System-defined identity policy
OMSReadOnlyPolicy	Read-only permissions for OMS. Users granted these permissions can only view OMS data.	System-defined identity policy

Table 4 lists the common operations supported by system-defined identity policies for OMS.

**Table 4** Common operations supported by system-defined identity policies of OMS
Operation	OMSFullAccessPolicy	OMSReadOnlyPolicy
Creating a migration task	Supported	Not supported
Updating migration tasks in batches	Supported	Not supported
Retrying migration tasks in batches	Supported	Not supported
Starting paused migration tasks in batches	Supported	Not supported
Pausing migration tasks in batches	Supported	Not supported
Listing migration tasks	Supported	Supported
Querying a migration task	Supported	Supported
Deleting a migration task	Supported	Not supported
Pausing a migration task	Supported	Not supported
Starting a migration task	Supported	Not supported
Modifying the traffic limiting rules of a migration task	Supported	Not supported
Listing synchronization tasks	Supported	Supported
Creating a synchronization task	Supported	Not supported
Querying a synchronization task	Supported	Supported
Deleting a synchronization task	Supported	Not supported
Querying statistics about a synchronization task	Supported	Supported
Pausing a synchronization task	Supported	Not supported
Starting a paused synchronization task	Supported	Not supported
Creating a synchronization event for a synchronization task	Supported	Not supported
Creating a migration task group	Supported	Not supported
Listing migration task groups	Supported	Supported
Querying a migration task group	Supported	Supported
Deleting a migration task group	Supported	Not supported
Pausing a migration task group	Supported	Not supported
Restarting a migration task group	Supported	Not supported
Listing objects in a bucket	Supported	Supported
Checking whether data in a source bucket can be obtained from CDN	Supported	Supported
Listing all buckets	Supported	Supported
Querying the region of a bucket	Supported	Supported
Checking whether a bucket has objects with a specified prefix	Supported	Supported
Querying regions supported for a cloud vendor	Supported	Supported
Querying supported cloud vendors	Supported	Supported