Identity-based policies for Amazon EC2

By default, users don't have permission to create or modify Amazon EC2 resources, or perform tasks using the Amazon EC2 API, Amazon EC2 console, or CLI. To allow users to create or modify resources and perform tasks, you must create IAM policies that grant users permission to use the specific resources and API actions they'll need, and then attach those policies to the users, groups, or IAM roles that require those permissions.

When you attach a policy to a user, group of users, or role it allows or denies the users permission to perform the specified tasks on the specified resources. For more general information about IAM policies, see Policies and permissions in IAM in the IAM User Guide. For more information about managing and creating custom IAM policies, see Managing IAM policies.

An IAM policy must grant or deny permissions to use one or more Amazon EC2 actions. It must also specify the resources that can be used with the action, which can be all resources, or in some cases, specific resources. The policy can also include conditions that you apply to the resource.

To get started, you can check whether the AWS managed policies for Amazon EC2 meet your needs. Otherwise, you can create your own custom policies. For more information, see AWS managed policies for Amazon EC2.

Policy syntax

An IAM policy is a JSON document that consists of one or more statements. Each statement is structured as follows.

{
  "Statement":[{
    "Effect":"effect",
    "Action":"action",
    "Resource":"arn",
    "Condition":{
      "condition":{
        "key":"value"
        }
      }
    }
  ]
}

There are various elements that make up a statement:

For more information about policy requirements, see the IAM JSON policy reference in the IAM User Guide. For example IAM policy statements for Amazon EC2, see Example policies to control access the Amazon EC2 API.

Actions for Amazon EC2

In an IAM policy statement, you can specify any API action from any service that supports IAM. For Amazon EC2, use the following prefix with the name of the API action: ec2:. For example: ec2:RunInstances and ec2:CreateImage.

To specify multiple actions in a single statement, separate them with commas as follows:

"Action": ["ec2:action1", "ec2:action2"]

You can also specify multiple actions using wildcards. For example, you can specify all actions whose name begins with the word "Describe" as follows:

"Action": "ec2:Describe*"

To specify all Amazon EC2 API actions, use the * wildcard as follows:

"Action": "ec2:*"

For a list of Amazon EC2 actions, see Actions defined by Amazon EC2 in the Service Authorization Reference.

Supported resource-level permissions for Amazon EC2 API actions

Resource-level permissions refers to the ability to specify which resources users are allowed to perform actions on. Amazon EC2 has partial support for resource-level permissions. This means that for certain Amazon EC2 actions, you can control when users are allowed to use those actions based on conditions that have to be fulfilled, or specific resources that users are allowed to use. For example, you can grant users permissions to launch instances, but only of a specific type, and only using a specific AMI.

To specify a resource in an IAM policy statement, use its Amazon Resource Name (ARN). For more information about specifying the ARN value, see Amazon Resource Names (ARNs) for Amazon EC2. If an API action does not support individual ARNs, you must use a wildcard (*) to specify that all resources can be affected by the action.

To see tables that identify which Amazon EC2 API actions support resource-level permissions, and the ARNs and condition keys that you can use in a policy, see Actions, resources, and condition keys for Amazon EC2.

Keep in mind that you can apply tag-based resource-level permissions in the IAM policies you use for Amazon EC2 API actions. This gives you better control over which resources a user can create, modify, or use. For more information, see Grant permission to tag Amazon EC2 resources during creation.

Amazon Resource Names (ARNs) for Amazon EC2

Each IAM policy statement applies to the resources that you specify using their ARNs.

An ARN has the following general syntax:

arn:aws:[service]:[region]:[account-id]:resourceType/resourcePath

For example, you can indicate a specific instance (i-1234567890abcdef0) in your statement using its ARN as follows.

"Resource": "arn:aws:ec2:us-east-1:123456789012:instance/i-1234567890abcdef0"

You can specify all instances that belong to a specific account by using the * wildcard as follows.

"Resource": "arn:aws:ec2:us-east-1:123456789012:instance/*"

You can also specify all Amazon EC2 resources that belong to a specific account by using the * wildcard as follows.

"Resource": "arn:aws:ec2:us-east-1:123456789012:*"

To specify all resources, or if a specific API action does not support ARNs, use the * wildcard in the Resource element as follows.

"Resource": "*"

Many Amazon EC2 API actions involve multiple resources. For example, AttachVolume attaches an Amazon EBS volume to an instance, so a user must have permissions to use the volume and the instance. To specify multiple resources in a single statement, separate their ARNs with commas, as follows.

"Resource": ["arn1", "arn2"]

For a list of ARNs for Amazon EC2 resources, see Resource types defined by Amazon EC2.

Condition keys for Amazon EC2

In a policy statement, you can optionally specify conditions that control when it is in effect. Each condition contains one or more key-value pairs. Condition keys are not case-sensitive. We've defined AWS global condition keys, plus additional service-specific condition keys.

For a list of service-specific condition keys for Amazon EC2, see Condition keys for Amazon EC2. Amazon EC2 also implements the AWS global condition keys. For more information, see Information available in all requests in the IAM User Guide.

All Amazon EC2 actions support the aws:RequestedRegion and ec2:Region condition keys. For more information, see Example: Restrict access to a specific Region.

To use a condition key in your IAM policy, use the Condition statement. For example, the following policy grants users permission to add and remove inbound and outbound rules for any security group. It uses the ec2:Vpc condition key to specify that these actions can only be performed on security groups in a specific VPC.

{
"Version": "2012-10-17",
  "Statement":[{
    "Effect":"Allow",
    "Action": [
       "ec2:AuthorizeSecurityGroupIngress",
       "ec2:AuthorizeSecurityGroupEgress",
       "ec2:RevokeSecurityGroupIngress",
       "ec2:RevokeSecurityGroupEgress"],
     "Resource": "arn:aws:ec2:region:account:security-group/*",
      "Condition": {
        "StringEquals": {
          "ec2:Vpc": "arn:aws:ec2:region:account:vpc/vpc-11223344556677889"
        }
      }
    }
  ]
}

If you specify multiple conditions, or multiple keys in a single condition, we evaluate them using a logical AND operation. If you specify a single condition with multiple values for one key, we evaluate the condition using a logical OR operation. For permissions to be granted, all conditions must be met.

You can also use placeholders when you specify conditions. For more information, see IAM policy elements: Variables and tags in the IAM User Guide.

ec2:Attribute condition key

The ec2:Attribute condition key can be used for conditions that filter access by an attribute of a resource.

This condition key supports only properties that are of a primitive data type (such as strings or integers), or complex AttributeValue objects that contain only a Value property (such as the Description or ImdsSupport objects of the ModifyImageAttribute API action). The condition key can't be used with complex objects that contain multiple properties, such as the LaunchPermission object of ModifyImageAttribute.

For example, the following policy uses the ec2:Attribute/Description condition key to filter access by the complex Description object of the ModifyImageAttribute API action. The condition key allows only requests that modify an image's description to either Production or Development.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "ec2:ModifyImageAttribute",
      "Resource": "arn:aws:ec2:us-east-1::image/ami-*",
      "Condition": {
        "StringEquals": {
          "ec2:Attribute/Description": [
            "Production",
            "Development"
          ]
        }
      }
    }
  ]
}

The following example policy uses the ec2:Attribute condition key to filter access by the primitive Attribute property of the ModifyImageAttribute API action. The condition key denies all requests that attempt to modify an image's description.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Deny",
      "Action": "ec2:ModifyImageAttribute",
      "Resource": "arn:aws:ec2:us-east-1::image/ami-*",
      "Condition": {
        "StringEquals": {
          "ec2:Attribute": "Description"
        }
      }
    }
  ]
}

ec2:ResourceID condition keys

When using the following ec2:ResourceID condition keys with the specified API actions, the condition key value is used to specify the resulting resource that is created by the API action. ec2:ResourceID condition keys can't be used to specify a source resource that is specified in the API request. If you use one of the following ec2:ResourceID condition keys with a specified API, then you must always specify the wildcard (*). If you specify a different value, the condition always resolves to * during runtime. For example, to use the ec2:ImageId condition key with the CopyImage API, then you must specify the condition key as follows:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "ec2:CopyImage",
      "Resource": "arn:aws:ec2:us-east-1::image/ami-*",
      "Condition": {
        "StringEquals": {
          ec2:ImageID": "*"
        }
      }
    }
  ]
}

We recommend that you avoid using these condition keys with these API actions:

To filter access based on specific resource IDs, we recommend that you use the Resource policy element as follows.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": "ec2:CopyImage",
      "Resource": "arn:aws:ec2:us-east-1::image/ami-01234567890abcdef"
    }
  ]
}

ec2:SourceInstanceARN condition key

Use ec2:SourceInstanceARN to specify the ARN of the instance from which a request is made. This is an AWS global condition key, which means that you can use it with services other than Amazon EC2. For a policy example, see Example: Allow a specific instance to view resources in other AWS services.

Control access using attribute-based access

When you create an IAM policy that grants users permission to use EC2 resources, you can include tag information in the Condition element of the policy to control access based on tags. This is known as attribute-based access control (ABAC). ABAC provides better control over which resources a user can modify, use, or delete. For more information, see What is ABAC for AWS?

For example, you can create a policy that allows users to terminate an instance, but denies the action if the instance has the tag environment=production. To do this, you use the aws:ResourceTag condition key to allow or deny access to the resource based on the tags that are attached to the resource.

"StringEquals": { "aws:ResourceTag/environment": "production" }

To learn whether an Amazon EC2 API action supports controlling access using the aws:ResourceTag condition key, see Actions, resources, and condition keys for Amazon EC2. Note that the Describe actions do not support resource-level permissions, so you must specify them in a separate statement without conditions.

For example IAM policies, see Example policies to control access the Amazon EC2 API.

If you allow or deny users access to resources based on tags, you must consider explicitly denying users the ability to add those tags to or remove them from the same resources. Otherwise, it's possible for a user to circumvent your restrictions and gain access to a resource by modifying its tags.

Grant permissions to users, groups, and roles

To provide access, add permissions to your users, groups, or roles:

Check that users have the required permissions

After you've created an IAM policy, we recommend that you check whether it grants users the permissions to use the particular API actions and resources they need before you put the policy into production.

First, create a user for testing purposes, and then attach the IAM policy that you created to the test user. Then, make a request as the test user.

If the Amazon EC2 action that you are testing creates or modifies a resource, you should make the request using the DryRun parameter (or run the AWS CLI command with the --dry-run option). In this case, the call completes the authorization check, but does not complete the operation. For example, you can check whether the user can terminate a particular instance without actually terminating it. If the test user has the required permissions, the request returns DryRunOperation; otherwise, it returns UnauthorizedOperation.

If the policy doesn't grant the user the permissions that you expected, or is overly permissive, you can adjust the policy as needed and retest until you get the desired results.

If an authorization check fails, the request returns an encoded message with diagnostic information. You can decode the message using the DecodeAuthorizationMessage action. For more information, see DecodeAuthorizationMessage in the AWS Security Token Service API Reference, and decode-authorization-message in the AWS CLI Command Reference.