# Using service-linked roles for AWS KMS
AWS Key Management Service uses AWS Identity and Access Management (IAM)[ service-linked roles](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_terms-and-concepts.html#iam-term-service-linked-role). A service-linked role is a unique type of IAM role that is linked directly to AWS KMS. Service-linked roles are defined by AWS KMS and include all the permissions that the service requires to call other AWS services on your behalf.
A service-linked role makes setting up AWS KMS easier because you don’t have to manually add the necessary permissions. AWS KMS defines the permissions of its service-linked roles, and unless defined otherwise, only AWS KMS can assume its roles. The defined permissions include the trust policy and the permissions policy, and that permissions policy cannot be attached to any other IAM entity.
You can delete a service-linked role only after first deleting the related resources. This protects your AWS KMS resources because you can't inadvertently remove permission to access the resources.
For information about other services that support service-linked roles, see [AWS Services That Work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) and look for the services that have **Yes **in the **Service-Linked Role** column. Choose a **Yes** with a link to view the service-linked role documentation for that service.
To view details about updates to the service-linked roles discussed in this topic, see [AWS KMS updates to AWS managed policies](security-iam-awsmanpol.md#security-iam-awsmanpol-updates).
**Topics**
+ [Authorizing AWS KMS to manage AWS CloudHSM and Amazon EC2 resources](authorize-kms.md)
+ [Authorizing AWS KMS to synchronize multi-Region keys](multi-region-auth-slr.md)
# Authorizing AWS KMS to manage AWS CloudHSM and Amazon EC2 resources
To support your AWS CloudHSM key stores, AWS KMS needs permission to get information about your AWS CloudHSM clusters. It also needs permission to create the network infrastructure that connects your AWS CloudHSM key store to its AWS CloudHSM cluster. To get these permissions, AWS KMS creates the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** service-linked role in your AWS account. Users who create AWS CloudHSM key stores must have the `iam:CreateServiceLinkedRole` permission that allows them to create service-linked roles.
To view details about updates to the **AWSKeyManagementServiceCustomKeyStoresServiceRolePolicy** managed policy, see [AWS KMS updates to AWS managed policies](security-iam-awsmanpol.md#security-iam-awsmanpol-updates).
**Topics**
+ [About the AWS KMS service-linked role](#about-key-store-slr)
+ [Create the service-linked role](#create-key-store-slr)
+ [Edit the service-linked role description](#edit-key-store-slr)
+ [Delete the service-linked role](#delete-key-store-slr)
## About the AWS KMS service-linked role
A [service-linked role](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html) is an IAM role that gives one AWS service permission to call other AWS services on your behalf. It's designed to make it easier for you to use the features of multiple integrated AWS services without having to create and maintain complex IAM policies. For more information, see [Using service-linked roles for AWS KMS](using-service-linked-roles.md).
For AWS CloudHSM key stores, AWS KMS creates the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** service-linked role with the **AWSKeyManagementServiceCustomKeyStoresServiceRolePolicy** managed policy. This policy grants the role the following permissions:
+ [cloudhsm:Describe\$1](https://docs.aws.amazon.com/cloudhsm/latest/APIReference/API_DescribeClusters.html) – detects changes in the AWS CloudHSM cluster that is attached to your custom key store.
+ [ec2:CreateSecurityGroup](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_CreateSecurityGroup.html) – used when you [connect an AWS CloudHSM key store](connect-keystore.md) to create the security group that enables network traffic flow between AWS KMS and your AWS CloudHSM cluster.
+ [ec2:AuthorizeSecurityGroupIngress](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_AuthorizeSecurityGroupIngress.html) – used when you [connect an AWS CloudHSM key store](connect-keystore.md) to allow network access from AWS KMS into the VPC that contains your AWS CloudHSM cluster.
+ [ec2:CreateNetworkInterface](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_CreateNetworkInterface.html) – used when you [connect an AWS CloudHSM key store](connect-keystore.md) to create the network interface used for communication between AWS KMS and the AWS CloudHSM cluster.
+ [ec2:RevokeSecurityGroupEgress](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_RevokeSecurityGroupEgress.html) – used when you [connect an AWS CloudHSM key store](connect-keystore.md) to remove all outbound rules from the security group that AWS KMS created.
+ [ec2:DeleteSecurityGroup](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DeleteSecurityGroup.html) – used when you [disconnect an AWS CloudHSM key store](disconnect-keystore.md) to delete security groups that were created when you connected the AWS CloudHSM key store.
+ [ec2:DescribeSecurityGroups](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeSecurityGroups.html) – used to monitor changes in the security group that AWS KMS created in the VPC that contains your AWS CloudHSM cluster so that AWS KMS can provide clear error messages in case of failures.
+ [ec2:DescribeVpcs](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeVpcs.html) – used to monitor changes in the VPC that contains your AWS CloudHSM cluster so that AWS KMS can provide clear error messages in case of failures.
+ [ec2:DescribeNetworkAcls](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeNetworkAcls.html) – used to monitor changes in the network ACLs for the VPC that contains your AWS CloudHSM cluster so that AWS KMS can provide clear error messages in case of failures.
+ [ec2:DescribeNetworkInterfaces](https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_DescribeNetworkInterfaces.html) – used to monitor changes in the network interfaces that AWS KMS created in the VPC that contains your AWS CloudHSM cluster so that AWS KMS can provide clear error messages in case of failures.
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"cloudhsm:Describe*",
"ec2:CreateNetworkInterface",
"ec2:AuthorizeSecurityGroupIngress",
"ec2:CreateSecurityGroup",
"ec2:DescribeSecurityGroups",
"ec2:RevokeSecurityGroupEgress",
"ec2:DeleteSecurityGroup",
"ec2:DescribeVpcs",
"ec2:DescribeNetworkAcls",
"ec2:DescribeNetworkInterfaces"
],
"Resource": "*"
}
]
}
```
------
Because the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** service-linked role trusts only `cks.kms.amazonaws.com`, only AWS KMS can assume this service-linked role. This role is limited to the operations that AWS KMS needs to view your AWS CloudHSM clusters and to connect an AWS CloudHSM key store to its associated AWS CloudHSM cluster. It does not give AWS KMS any additional permissions. For example, AWS KMS does not have permission to create, manage, or delete your AWS CloudHSM clusters, HSMs, or backups.
**Regions**
Like the AWS CloudHSM key stores feature, the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** role is supported in all AWS Regions where AWS KMS and AWS CloudHSM are available. For a list of AWS Regions that each service supports, see [AWS Key Management Service Endpoints and Quotas](https://docs.aws.amazon.com/general/latest/gr/kms.html) and [AWS CloudHSM endpoints and quotas](https://docs.aws.amazon.com/general/latest/gr/cloudhsm.html) in the *Amazon Web Services General Reference*.
For more information about how AWS services use service-linked roles, see [Using service-linked roles](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html) in the IAM User Guide.
## Create the service-linked role
AWS KMS automatically creates the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** service-linked role in your AWS account when you create an AWS CloudHSM key store, if the role does not already exist. You cannot create or re-create this service-linked role directly.
## Edit the service-linked role description
You cannot edit the role name or the policy statements in the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** service-linked role, but you can edit role description. For instructions, see [Editing a service-linked role](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html#edit-service-linked-role) in the *IAM User Guide*.
## Delete the service-linked role
AWS KMS does not delete the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** service-linked role from your AWS account even if you have [deleted all of your AWS CloudHSM key stores](delete-keystore.md). Although there is currently no procedure for deleting the **AWSServiceRoleForKeyManagementServiceCustomKeyStores** service-linked role, AWS KMS does not assume this role or use its permissions unless you have active AWS CloudHSM key stores.
# Authorizing AWS KMS to synchronize multi-Region keys
To support [multi-Region keys](multi-region-keys-auth.md), AWS KMS needs permission to synchronize the [shared properties](multi-region-keys-overview.md#mrk-sync-properties) of a multi-Region primary key with its replica keys. To get these permissions, AWS KMS creates the **AWSServiceRoleForKeyManagementServiceMultiRegionKeys** service-linked role in your AWS account. Users who create multi-Region keys must have the `iam:CreateServiceLinkedRole` permission that allows them to create service-linked roles.
You can view the [SynchronizeMultiRegionKey](ct-synchronize-multi-region-key.md) CloudTrail event that records AWS KMS synchronizing shared properties in your AWS CloudTrail logs.
To view details about updates to the **AWSKeyManagementServiceMultiRegionKeysServiceRolePolicy** managed policy, see [AWS KMS updates to AWS managed policies](security-iam-awsmanpol.md#security-iam-awsmanpol-updates).
**Topics**
+ [About the service-linked role for multi-Region keys](#about-multi-region-slr)
+ [Create the service-linked role](#create-mrk-slr)
+ [Edit the service-linked role description](#edit-mrk-slr)
+ [Delete the service-linked role](#delete-mrk-slr)
## About the service-linked role for multi-Region keys
A [service-linked role](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html) is an IAM role that gives one AWS service permission to call other AWS services on your behalf. It's designed to make it easier for you to use the features of multiple integrated AWS services without having to create and maintain complex IAM policies.
For multi-Region keys, AWS KMS creates the **AWSServiceRoleForKeyManagementServiceMultiRegionKeys** service-linked role with the **AWSKeyManagementServiceMultiRegionKeysServiceRolePolicy** managed policy. This policy gives the role the `kms:SynchronizeMultiRegionKey` permission, which allows it to synchronize the shared properties of multi-Region keys.
Because the **AWSServiceRoleForKeyManagementServiceMultiRegionKeys** service-linked role trusts only `mrk.kms.amazonaws.com`, only AWS KMS can assume this service-linked role. This role is limited to the operations that AWS KMS needs to synchronize multi-Region shared properties. It does not give AWS KMS any additional permissions. For example, AWS KMS does not have permission to create, replicate, or delete any KMS keys.
For more information about how AWS services use service-linked roles, see [Using Service-Linked Roles](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html) in the IAM User Guide.
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement" : [
{
"Sid" : "KMSSynchronizeMultiRegionKey",
"Effect" : "Allow",
"Action" : [
"kms:SynchronizeMultiRegionKey"
],
"Resource" : "*"
}
]
}
```
------
## Create the service-linked role
AWS KMS automatically creates the **AWSServiceRoleForKeyManagementServiceMultiRegionKeys** service-linked role in your AWS account when you create a multi-Region key, if the role does not already exist. You cannot create or re-create this service-linked role directly.
## Edit the service-linked role description
You cannot edit the role name or the policy statements in the **AWSServiceRoleForKeyManagementServiceMultiRegionKeys** service-linked role, but you can edit the role description. For instructions, see [Editing a Service-Linked Role](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html#edit-service-linked-role) in the *IAM User Guide*.
## Delete the service-linked role
AWS KMS does not delete the **AWSServiceRoleForKeyManagementServiceMultiRegionKeys** service-linked role from your AWS account and you cannot delete it. However, AWS KMS does not assume the **AWSServiceRoleForKeyManagementServiceMultiRegionKeys** role or use any of its permissions unless you have multi-Region keys in your AWS account and Region.