IAM Permissions Overview

By default, newly created IAM users do not have any permissions. You need to add the user to one or more groups, and attach permission 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.

IAM permissions apply to all OBS buckets and objects. To grant an IAM user the permission to operate OBS resources, you need to assign one or more OBS permission sets to the user group that the user belongs to.

OBS is a global service because it is available in all physical regions. If users in the global project are assigned IAM permissions, they do not need to switch regions to access OBS.

You can grant permissions to users by roles and policies.

Roles: A type of coarse-grained authorization mechanism that defines permissions related to user responsibilities. This mechanism only provides a limited number of service-level roles for authorization. When using roles to grant permissions, you also need to assign other dependency roles. However, roles are not the best choice for fine-grained authorization and secure access control.
Policies: A type of fine-grained authorization mechanism that defines permissions required to perform operations on specific cloud resources under certain conditions. This mechanism allows for more flexible policy-based authorization, meeting requirements for secure access control. For example, you can grant OBS users only the permissions to manage a certain type of OBS resources.

Due to data caching, a role and policy involving OBS actions will take effect 10 to 15 minutes after it is attached to a user, an enterprise project, or a user group.

IAM presets system permissions for each cloud service so that you can quickly configure basic permissions. Table 1 describes all system permissions of OBS.

Custom policies can be created to supplement the system-defined policies of OBS.

**Table 1** OBS system permissions
Role/Policy Name	Description	Type	Dependency
Tenant Administrator	Users with this permission can perform all operations on all services except IAM.	System-defined role	N/A
Tenant Guest	Users with this permission can perform read-only operations on all services except IAM.	System-defined role	N/A
OBS Administrator	Users with this permission are OBS administrators and can perform any operations on all OBS resources under the account.	System-defined role	N/A
OBS Buckets Viewer	Users with this permission can list buckets, obtain basic information about buckets, and obtain bucket metadata.	System-defined role	N/A
OBS ReadOnlyAccess	Users with this permission can list buckets, obtain basic information about buckets, obtain bucket metadata, and list objects (not the objects that have been versioned). NOTE: If a user with this permission fails to list objects on OBS Console, there may be multiple versions of objects in the bucket. In this case, you need to grant the user the obs:bucket:ListBucketVersions permission so that the user can view different versions of objects on OBS Console.	System-defined policy	N/A
OBS OperateAccess	Users with this permission can perform all OBS ReadOnlyAccess operations and perform basic operations on objects, such as uploading, downloading, and deleting objects, and obtaining object ACLs. NOTE: If a user with this permission fails to list objects on OBS Console, there may be multiple versions of objects in the bucket. In this case, you need to grant the user the obs:bucket:ListBucketVersions permission so that the user can view different versions of objects on OBS Console.	System-defined policy	N/A

The following table lists the common operations supported by system-defined permissions for OBS. You can refer to this table to select the permissions as required.

**Table 2** Permissions and allowed operations on OBS resources
Operation	Tenant Administrator	Tenant Guest	OBS Administrator	OBS Buckets Viewer	OBS ReadOnlyAccess	OBS OperateAccess
Listing buckets	Yes	Yes	Yes	Yes	Yes	Yes
Creating buckets	Yes	No	Yes	No	No	No
Deleting buckets	Yes	No	Yes	No	No	No
Obtaining basic information about buckets	Yes	Yes	Yes	Yes	Yes	Yes
Controlling bucket access	Yes	No	Yes	No	No	No
Managing bucket policies	Yes	No	Yes	No	No	No
Modifying bucket storage classes	Yes	No	Yes	No	No	No
Listing objects	Yes	Yes	Yes	No	Yes	Yes
Listing versioned objects	Yes	Yes	Yes	No	No	No
Uploading a file	Yes	No	Yes	No	No	Yes
Creating a folder	Yes	No	Yes	No	No	Yes
Deleting a file	Yes	No	Yes	No	No	Yes
Deleting a folder	Yes	No	Yes	No	No	Yes
Downloading a file	Yes	Yes	Yes	No	No	Yes
Deleting files with multiple versions	Yes	No	Yes	No	No	Yes
Downloading files with multiple versions	Yes	Yes	Yes	No	No	Yes
Modifying object storage classes	Yes	No	Yes	No	No	No
Restoring files	Yes	No	Yes	No	No	No
Undeleting a file	Yes	No	Yes	No	No	Yes
Deleting fragments	Yes	No	Yes	No	No	Yes
Controlling access to objects	Yes	No	Yes	No	No	No
Configuring object metadata	Yes	No	Yes	No	No	No
Obtaining object metadata	Yes	Yes	Yes	No	No	Yes
Managing versioning	Yes	No	Yes	No	No	No
Managing logging	Yes	No	Yes	No	No	No
Managing event notifications	Yes	No	Yes	No	No	No
Managing tags	Yes	No	Yes	No	No	No
Managing lifecycle rules	Yes	No	Yes	No	No	No
Managing static website hosting	Yes	No	Yes	No	No	No
Managing CORS rules	Yes	No	Yes	No	No	No
Managing URL validation	Yes	No	Yes	No	No	No
Managing domain names	Yes	No	Yes	No	No	No
Managing cross-region replication	Yes	No	Yes	No	No	No
Configuring an object ACL	Yes	No	Yes	No	No	No
Configuring ACL for an object of a specified version	Yes	No	Yes	No	No	No
Obtaining an object ACL	Yes	Yes	Yes	No	No	Yes
Obtaining the ACL of a specific object version	Yes	Yes	Yes	No	No	Yes
Performing a multipart upload	Yes	No	Yes	No	No	Yes
Listing uploaded parts	Yes	Yes	Yes	No	No	Yes
Canceling a multipart upload	Yes	No	Yes	No	No	Yes
Configuring requester-pays	Yes	No	Yes	No	No	No
Obtaining requester-pays configuration information	Yes	Yes	Yes	No	No	No

Application Scenarios of IAM Permissions

IAM permissions control IAM users under an account to access:

All cloud resources.
All OBS buckets and objects.
Specified OBS resources.

Policy Structure and Syntax

A policy consists of a version and one or more statements.

Figure 1 Policy structure

Policy syntax example:

{
	"Version": "1.1",
	"Statement": [
                {
			"Effect": "Allow",
			"Action": [
				"obs:bucket:HeadBucket",
				"obs:bucket:ListBucket",
				"obs:bucket:GetBucketLocation"
			],
			"Resource": [
				"obs:*:*:bucket:*"
			],
			"Condition": {
				"StringEndWithIfExsits": {
					"g:UserName": ["specialCharacter"]
				},
				"Bool": {
					"g:MFAPresent": ["true"]
				}
			}
		}
	]
}

**Table 3** Policy syntax parameters
Parameter	Description
Version	The version number of a policy. 1.0: RBAC policy. An RBAC policy consists of permissions for an entire service. Users in a group with such a policy assigned are granted all of the permissions required for that service. 1.1: Fine-grained policy. A fine-grained policy consists of API-based permissions for operations on specific resource types. Fine-grained policies, as the name suggests, allow for more fine-grained control on specific operations and resources than RBAC policies. For example, you can restrict an IAM user to access only the objects in a specific directory of an OBS bucket.
Statement	Descriptions of a policy, including Effect, Action, Resource (optional), and Condition (optional). Effect The value of Effect can be Allow or Deny. System policies contain only Allow statements. For custom policies containing both Allow and Deny statements, Deny statements take precedence over Allow statements. Action Actions allowed on resources. An action is in the format of Service name:Resource type:Action. A policy can contain one or more actions. You can use a wildcard () to indicate all services, resource types, or actions. There are two types of OBS resources: buckets and objects. Resource* Resources on which the policy takes effect. A resource is in the format of Service name:Region:Domain ID:Resource type:Resource path. You can use a wildcard () to indicate all services, regions, domain IDs, resource types, or resource paths. In the JSON view, if Resource* is not specified, the policy applies to all resources. The value of Resource can only contain uppercase (A to Z), lowercase (a to z) letters, digits (0 to 9), and the following characters: *-_./\*. If you want to specify unsupported characters, use the wildcard character (). OBS is a global service. Therefore, set Region to . Domain ID* indicates the ID of the resource owner. Set it to * to indicate the ID of the account that the resources belong to. Examples: obs:::bucket:: all OBS buckets obs:::object:my-bucket/my-object/: all objects in the my-object directory of bucket my-bucket Condition When creating a custom policy, you can add conditions to control when the policy takes effect. A condition consists of a condition key and an operator. Condition keys are either global or service-level. Global condition keys (starting with g:) are available for actions on all services, while service-level condition keys (starting with a service name acronym like obs:) are available only for actions on a specific service. An operator is used together with a condition key to form a complete condition statement. OBS has predefined a group of condition keys for use in IAM. For example, you can use the condition key obs:SourceIp to allow access from a specific IP address. The condition keys and operators supported by OBS are the same as those in the bucket policy. When configuring condition keys in IAM, start the condition keys and operators with obs:. For detailed conditions, see Bucket Policy Parameters. The value of Condition can only contain uppercase letters (A to Z), lowercase letters (a to z), digits (0 to 9), and the following characters: -,./_@#$%&. If you want to specify unsupported characters, use the condition operators (like StringMatch) for fuzzy match. Examples: StringEndWithIfExists":{"g:UserName":["specialCharacter"]}: The statement is valid for users whose names end with specialCharacter. "StringLike":{"obs:prefix":["private/"]}: When listing objects in a bucket, you need to set prefix to private/ or include private/.

Configuring IAM Permissions

Example Custom Policies

Example 1: Grant permissions that allow full access to OBS.
This policy allows users to perform any operation on OBS using the API, SDKs, OBS Console, or tools.
If a user logs in to OBS Console and also accesses resources of other services, such as audit information in CTS, acceleration domain names in CDN, and keys in KMS, in addition to the OBS permissions, you need to grant users the permissions to access these services. CDN is a global service. CTS, SMN, and KMS are regional services. You need to configure the Tenant Guest permission for the global project and regional projects based on the services and regions that you use.
```
{
    "Version": "1.1",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "obs:*:*"
            ]
        }
    ]
}
```

Example 2: Grant permissions that allow read-only access to a bucket (any directory).

This policy allows users to list and download all objects from bucket obs-example.

{
    "Version": "1.1",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "obs:object:GetObject",
                "obs:bucket:ListBucket"
            ],
            "Resource": [
                "obs:*:*:object:obs-example/*",
                "obs:*:*:bucket:obs-example"
            ]
        }
    ]
}

Example 3: Grant permissions that allow read-only access to a bucket (a specified directory).

This policy allows users to download objects only from the my-project/ directory of bucket obs-example. Objects in other directories can be listed but cannot be downloaded.

{
    "Version": "1.1",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "obs:object:GetObject",
                "obs:bucket:ListBucket"
            ],
            "Resource": [
                "obs:*:*:object:obs-example/my-project/*",
                "obs:*:*:bucket:obs-example"
            ]
        }
    ]
}

Example 4: Grant permissions that allow read and write access to a bucket (a specified directory).

This policy allows users to list, download, upload, and delete objects in the my-project directory of bucket obs-example.

{
    "Version": "1.1",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "obs:object:GetObject",
                "obs:object:ListMultipartUploadParts",
                "obs:bucket:ListBucket",
                "obs:object:DeleteObject",
                "obs:object:PutObject"
            ],
            "Resource": [
                "obs:*:*:object:obs-example/my-project/*",
                "obs:*:*:bucket:obs-example"
            ]
        }
    ]
}

Example 5: Grant permissions that allow full access to a bucket.

This policy allows users to perform any operation on bucket obs-example.

{
    "Version": "1.1",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "obs:*:*"
            ],
            "Resource": [
                "obs:*:*:bucket:obs-example",
                "obs:*:*:object:obs-example/*"
            ]
        }
    ]
}

Example 6: Deny object upload.
A policy with only Deny statements must be used together other policies. If the policy assigned to a user contains both Allow and Deny statements, the Deny statement take precedence over the Allow statement.

If you need to assign OBS OperateAccess permissions to a user but prevent the user from uploading objects, you can create a custom policy to deny object upload, and assign this custom policy and OBS OperateAccess to the user. Then the user can perform all operations allowed by OBS OperateAccess except for uploading objects. The following is an example of a deny policy:
```
{
    "Version": "1.1",
    "Statement": [
        {
            "Effect": "Deny",
            "Action": [
                "obs:object:PutObject"
            ]
        }
    ]
}
```

Example 7: Grant the permissions to change a bucket's storage class and delete certain objects from the bucket.

This policy allows users to change the storage class of bucket obs-example and to delete object my-object.txt from the bucket.

{
    "Version": "1.1",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "obs:bucket:ListAllMyBuckets",
                "obs:bucket:ListBucket"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "obs:object:DeleteObject",
                "obs:bucket:PutBucketStoragePolicy"
            ],
            "Resource": [
                "OBS:*:*:object:obs-example/my-object.txt",
                "OBS:*:*:bucket:obs-example"
            ]
        }
    ]
}