Granting an IAM User the Specified Permissions for Certain Objects

Scenario

This topic describes how to grant an IAM user the specified permissions on certain objects in a bucket. Below explains how to grant the object download permission.

If you need to configure other permissions, select the corresponding actions from the Action Name drop-down list in the bucket policy. For details about the actions supported by OBS, see Action/NotAction.

Recommended Configuration

You are advised to use bucket policies to grant resource-level permissions to an IAM user.

Configuration Precautions

After the configuration is complete, you can download objects using APIs. However, if you log in to OBS Console or OBS Browser+ to download an object, an error is reported indicating that you do not have required permissions.

This is because when you log in to OBS Console or OBS Browser+, APIs (such as ListAllMyBuckets and ListBucket) are called to load the bucket list and object list and some other APIs will also be called on other pages, but your permissions do not cover those APIs. In such case, your access is denied or your operation is not allowed.

If you want an IAM user to successfully download objects on OBS Console or OBS Browser+, configure custom IAM policies by referring to Follow-up Procedure.

Procedure

1. In the navigation pane of OBS Console, choose Object Storage.
2. In the bucket list, click the bucket name you want to go to the Overview page.
3. In the navigation pane, choose Permissions.
4. On the Bucket Policies page, click Create Bucket Policy under Custom Bucket Policies.
5. Configure parameters for a bucket policy.

   Table 1 Parameters for creating a bucket policy

   Parameter	Description
   Policy Mode	Select Customized.
   Effect	Select Allow.
   Principal	Select Include > Current account. Username: Select an IAM user whom you want to grant permissions to.
   Resources	Choose Include > Specific resources. Resource Name: Enter the object or the set of objects that will be accessed. For one object, enter object name. For a set of objects, enter object name prefix + *, * + object name suffix, or *.
   Actions	Include Action Name: Select GetObject. To configure other permissions, select the corresponding actions. For details about the actions supported by OBS, see Action/NotAction.

6. Click OK. The bucket policy is created.

Follow-up Procedure

To perform specific operations on OBS Console or OBS Browser+, you must add the obs:bucket:ListAllMyBuckets (for listing buckets) and obs:bucket:ListBucket (for listing objects in a bucket) permissions to the custom IAM policy.

obs:bucket:ListAllMyBuckets applies to all resources, while obs:bucket:ListBucket applies to the authorized bucket only. Therefore, you need to add two permissions to the policy.

1. Log in to the management console using a cloud service account.
2. On the top menu bar, choose Service List > Management & Deployment > Identity and Access Management. The IAM console is displayed.
3. In the navigation pane, choose Policies.
4. Click Create Custom Policy in the upper right corner.
5. Configure parameters for a custom policy.

   Table 2 Parameters for configuring a custom policy

   Parameter	Description
   Policy Name	Name of the custom policy
   Policy View	Set this parameter based on your own habits. Visual editor is used here.
   Policy Content	[Permission 1] Select Allow. Select Object Storage Service (OBS). Select obs:bucket:ListAllMyBuckets from the actions. Select All for resources. [Permission 2] Select Allow. Select Object Storage Service (OBS). Select obs:bucket:ListBucket from the actions. For Resources, select Specific, and for bucket, select Specify resource path, and click Add Resource Path. Enter the bucket name in the Path text box, indicating that the policy takes effect only for this bucket.
   Scope	The default value is Global services.

6. Click OK. The custom policy is created.
7. Create a user group and assign permissions.

   Add the created custom policy to the user group by following the instructions in the IAM document.

8. Add the IAM user you want to authorize to the created user group by referring to Adding Users to or Removing Users from a User Group.
   

   Due to data caching, it takes about 10 to 15 minutes for a custom policy to take effect after the authorization.