# Securing your data in Amazon EFS
Cloud security at AWS is the highest priority. As an AWS customer, you benefit from a data center and network architecture that is built to meet the requirements of the most security-sensitive organizations.
Security is a shared responsibility between AWS and you. The [shared responsibility model](https://aws.amazon.com/compliance/shared-responsibility-model/) describes this as security *of* the cloud and security *in* the cloud:
+ **Security of the cloud** – AWS is responsible for protecting the infrastructure that runs AWS services in the AWS Cloud. AWS also provides you with services that you can use securely. Third-party auditors regularly test and verify the effectiveness of our security as part of the [AWS Compliance Programs](https://aws.amazon.com/compliance/programs/). To learn about the compliance programs that apply to Amazon Elastic File System, see [AWS Services in Scope by Compliance Program](https://aws.amazon.com/compliance/services-in-scope/).
+ **Security in the cloud** – Your responsibility is determined by the AWS service that you use. You are also responsible for other factors including the sensitivity of your data, your company’s requirements, and applicable laws and regulations.
This documentation helps you understand how to apply the shared responsibility model when using Amazon EFS. The following topics show you how to configure Amazon EFS to meet your security and compliance objectives. You also learn how to use other AWS services that help you to monitor and secure your Amazon EFS resources.
**Topics**
+ [Data protection in Amazon EFS](data-protection.md)
+ [Identity and access management for Amazon EFS](security-iam.md)
+ [Using IAM to control access to file systems](iam-access-control-nfs-efs.md)
+ [Compliance validation for Amazon EFS](EFS-compliance.md)
+ [Resilience in Amazon EFS](disaster-recovery-resiliency.md)
+ [Controlling network access to EFS file systems for NFS clients](NFS-access-control-efs.md)
+ [Network File System (NFS) level users, groups, and permissions](accessing-fs-nfs-permissions.md)
+ [Working with access points](efs-access-points.md)
+ [Blocking public access to EFS file systems](access-control-block-public-access.md)
+ [Network isolation for Amazon EFS](network-isolation.md)
# Data protection in Amazon EFS
The AWS [shared responsibility model](https://aws.amazon.com/compliance/shared-responsibility-model/) applies to data protection in Amazon EFS. As described in this model, AWS is responsible for protecting the global infrastructure that runs all of the AWS Cloud. You are responsible for maintaining control over your content that is hosted on this infrastructure. You are also responsible for the security configuration and management tasks for the AWS services that you use. For more information about data privacy, see the [Data Privacy FAQ](https://aws.amazon.com/compliance/data-privacy-faq/). For information about data protection in Europe, see the [AWS Shared Responsibility Model and GDPR](https://aws.amazon.com/blogs/security/the-aws-shared-responsibility-model-and-gdpr/) blog post on the *AWS Security Blog*.
For data protection purposes, we recommend that you protect AWS account credentials and set up individual users with AWS IAM Identity Center or AWS Identity and Access Management (IAM). That way, each user is given only the permissions necessary to fulfill their job duties. We also recommend that you secure your data in the following ways:
+ Use multi-factor authentication (MFA) with each account.
+ Use SSL/TLS to communicate with AWS resources. We require TLS 1.2 and recommend TLS 1.3.
+ Set up API and user activity logging with AWS CloudTrail. For information about using CloudTrail trails to capture AWS activities, see [Working with CloudTrail trails](https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudtrail-trails.html) in the *AWS CloudTrail User Guide*.
+ Use AWS encryption solutions, along with all default security controls within AWS services.
+ Use advanced managed security services such as Amazon Macie, which assists in discovering and securing sensitive data that is stored in Amazon S3.
+ If you require FIPS 140-3 validated cryptographic modules when accessing AWS through a command line interface or an API, use a FIPS endpoint. For more information about the available FIPS endpoints, see [Federal Information Processing Standard (FIPS) 140-3](https://aws.amazon.com/compliance/fips/).
We strongly recommend that you never put confidential or sensitive information, such as your customers' email addresses, into tags or free-form text fields such as a **Name** field. This includes when you work with Amazon EFS or other AWS services using the console, API, AWS CLI, or AWS SDKs. Any data that you enter into tags or free-form text fields used for names may be used for billing or diagnostic logs. If you provide a URL to an external server, we strongly recommend that you do not include credentials information in the URL to validate your request to that server.
**Topics**
+ [Data encryption in Amazon EFS](encryption.md)
+ [Internetwork privacy](internetwork-privacy.md)
# Data encryption in Amazon EFS
Amazon EFS provides comprehensive encryption capabilities to protect your data both at rest and in transit.
+ **Encryption at rest** – Encrypts data stored on your file system.
+ **Encryption in transit** – Encrypts data as it travels between your clients and the file system.
If your organization is subject to corporate or regulatory policies that require encryption of data and metadata, we recommend creating a file system that is encrypted at rest and mounting your file system using encryption of data in transit.
**Topics**
+ [Encrypting data at rest](encryption-at-rest.md)
+ [Encrypting data in transit](encryption-in-transit.md)
+ [Using AWS KMS keys for Amazon EFS](EFSKMS.md)
+ [Troubleshooting encryption](troubleshooting-efs-encryption.md)
# Encrypting data at rest
Encryption at rest encrypts data stored on your EFS file system. This helps you meet compliance requirements and protect sensitive data from unauthorized access. Your organization might require encryption of all data that meets a specific classification or is associated with a particular application, workload, or environment.
**Note**
The AWS key management infrastructure uses Federal Information Processing Standards (FIPS) 140-3 approved cryptographic algorithms. The infrastructure is consistent with National Institute of Standards and Technology (NIST) 800-57 recommendations.
When you create a file system using the Amazon EFS console, encryption at rest is enabled by default. When using the AWS CLI, API, or SDKs to create a file system, you must explicity enable encryption.
After you create an EFS file system, you cannot change its encryption setting. This means that you cannot modify an unencrypted file system to make it encrypted. Instead, [replicate the file system](efs-replication.md) to copy data from the unencrypted file system to a new encrypted file system. For more information, see [ How do I turn on encryption at rest for an existing EFS file system?](https://repost.aws/knowledge-center/efs-turn-on-encryption-at-rest)
## How encryption at rest works
In an encrypted file system, data and metadata are encrypted by default before being written to storage and are automatically decrypted when read. These processes are handled transparently by Amazon EFS, so you don't need to modify your applications.
Amazon EFS uses AWS KMS for key management as follows:
+ **File data encryption** – The contents of your files are encrypted using the KMS key that you specify. This can be either:
+ The AWS owned key for Amazon EFS (`aws/elasticfilesystem`) – Default option, no additional charges.
+ A customer managed key that you create and manage – Provides additional control and audit capabilities.
+ **Metadata encryption** - File names, directory names, and directory contents are encrypted using a key that Amazon EFS manages internally.
### Encryption process
When a file system is created or rerplicated to a file system in the same account, Amazon EFS uses a [ Forward Access Session (FAS)](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_forward_access_sessions.html) to make KMS calls using the caller's credentials. In CloudTrail logs, the `kms:CreateGrant` call appears to be made by the same user identity that created the file system or replication. You can identify Amazon EFS service calls in CloudTrail by looking for the `invokedBy` field with the value `elasticfilesystem.amazonaws.com`. The resource policy on the KMS key must allow the `CreateGrant` action for FAS to make the call.
**Important**
You manage control of the grant, and can revoke it at any time. Revoking the grant prevents Amazon EFS from accessing the KMS key for future operations. For more information, see [Retiring and revoking grants](https://docs.aws.amazon.com/kms/latest/developerguide/grant-delete.html) in the *AWS Key Management Service Developer Guide.*.
When using customer managed KMS keys, the resource policy must also allow the Amazon EFS service principal and include the `kms:ViaService` condition to restrict access to the specific service endpoint. For example:
```
"kms:ViaService":
"elasticfilesystem.us-east-2.amazonaws.com"
```
Amazon EFS uses industry-standard AES-256 encryption algorithm to encrypt data and metadata at rest.
For more information about KMS key policies for Amazon EFS, see [Using AWS KMS keys for Amazon EFS](EFSKMS.md).
## Enforcing encryption at rest for new file systems
You can use the `elasticfilesystem:Encrypted` IAM condition key in AWS Identity and Access Management (IAM) identity-based policies to enforce creation at rest when users create EFS file systems. For more information about using the condition key, see [Example: Enforce the creation of encrypted file systems](security_iam_id-based-policy-examples.md#using-iam-to-enforce-encryption-at-rest).
You can also define service control policies (SCPs) inside AWS Organizations to enforce Amazon EFS encryption for all AWS accounts in your organization. For more information about service control policies in AWS Organizations, see [Service control policies](https://docs.aws.amazon.com/organizations/latest/userguide/orgs_manage_policies_scps.html#orgs_manage_policies_scp) in the *AWS Organizations User Guide*.
# Encrypting data in transit
Amazon EFS supports encryption of data in transit with Transport Layer Security (TLS). When encryption of data in transit is declared as a mount option for your EFS file system, Amazon EFS establishes a secure TLS connection with your EFS file system upon mounting your file system. All NFS traffic is routed through this encrypted connection.
## How encrypting in transit works
We recommend using the EFS mount helper to mount your file system because it simplifies the mounting process as compared to mounting with NFS `mount`. The EFS mount helper manages the process by using either efs-proxy (for efs-utils version 2.0.0 and later) or stunnel (for efs-utils earlier versions) to establish a secure TLS connection with your EFS file system.
If you're not using the mount helper, you can still enable encryption of data in transit. The following are the steps to do so.
**To enable encryption of data in transit without using the mount helper**
1. Download and install `stunnel`, and note the port that the application is listening on. For more information, see [Upgrading `stunnel`](upgrading-stunnel.md).
1. Run `stunnel` to connect to your EFS file system on port 2049 using TLS.
1. Using the NFS client, mount `localhost:port`, where `port` is the port that you noted in the first step.
Because encryption of data in transit is configured on a per-connection basis, each configured mount has a dedicated `stunnel` process running on the instance. By default, the stunnel process used by the mount helper listens on a local port between 20049 and 20449, and it connects to Amazon EFS on port 2049.
**Note**
By default, when using the EFS mount helper with TLS, it enforces the use of the Online Certificate Status Protocol (OCSP) and certificate hostname checking. The EFS mount helper uses the stunnel program for its TLS functionality. Some versions of Linux don't include a version of stunnel that supports these TLS features by default. When using one of those Linux versions, mounting an EFS file system using TLS fails.
After you've installed the amazon-efs-utils package, to upgrade your system's version of stunnel, see [Upgrading `stunnel`](upgrading-stunnel.md).
For issues with encryption, see [Troubleshooting encryption](troubleshooting-efs-encryption.md).
When using encryption of data in transit, your NFS client setup is changed. When you inspect your actively mounted file systems, you see one mounted to 127.0.0.1, or `localhost`, as in the following example.
```
$ mount | column -t
127.0.0.1:/ on /home/ec2-user/efs type nfs4 (rw,relatime,vers=4.1,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=20127,timeo=600,retrans=2,sec=sys,clientaddr=127.0.0.1,local_lock=none,addr=127.0.0.1)
```
When mounting with TLS and the EFS mount helper, you are reconfiguring your NFS client to mount to a local port. The EFS mount helper starts a client `stunnel` process that is listening on this local port, and `stunnel` is opening an encrypted connection to the EFS file system using TLS. The EFS mount helper is responsible for setting up and maintaining this encrypted connection and the associated configuration.
To determine which Amazon EFS file system ID corresponds to which local mount point, you can use the following command. Remember to replace *efs-mount-point* with the local path where you’ve mounted your file system.
```
grep -E "Successfully mounted.*efs-mount-point" /var/log/amazon/efs/mount.log | tail -1
```
When you use the EFS mount helper for encryption of data in transit, it also creates a process called `amazon-efs-mount-watchdog`. This process ensures that each mount's stunnel process is running, and stops the stunnel when the EFS file system is unmounted. If for some reason a stunnel process is terminated unexpectedly, the watchdog process restarts it.
# Using AWS KMS keys for Amazon EFS
Amazon EFS integrates with AWS Key Management Service (AWS KMS) for key management. Amazon EFS uses customer managed keys to encrypt your file system in the following way:
+ **Encrypting metadata at rest** – Amazon EFS uses the AWS managed key for Amazon EFS, `aws/elasticfilesystem`, to encrypt and decrypt file system metadata (that is, file names, directory names, and directory contents).
+ **Encrypting file data at rest** – You choose the customer managed key used to encrypt and decrypt file data (that is, the contents of your files). You can enable, disable, or revoke grants on this customer managed key. This customer managed key can be one of the two following types:
+ **AWS managed key for Amazon EFS** – This is the default customer managed key, `aws/elasticfilesystem`. You're not charged to create and store a customer managed key, but there are usage charges. To learn more, see [AWS Key Management Service pricing](https://aws.amazon.com/kms/pricing/).
+ **Customer managed key** – This is the most flexible KMS key to use, because you can configure its key policies and grants for multiple users or services. For more information on creating customer managed keys, see [Creating keys](https://docs.aws.amazon.com/kms/latest/developerguide/create-keys.html) in the *AWS Key Management Service Developer Guide.*
If you use a customer managed key for file data encryption and decryption, you can enable key rotation. When you enable key rotation, AWS KMS automatically rotates your key once per year. Additionally, with a customer managed key, you can choose when to disable, re-enable, delete, or revoke access to your customer managed key at any time. For more information, see [Using AWS KMS keys for Amazon EFS](#EFSKMS).
**Important**
Amazon EFS accepts only symmetric customer managed keys. You cannot use asymmetric customer managed keys with Amazon EFS.
Data encryption and decryption at rest are handled transparently. However, AWS account IDs specific to Amazon EFS appear in your AWS CloudTrail logs related to AWS KMS actions. For more information, see [Amazon EFS log file entries for encrypted-at-rest file systems](logging-using-cloudtrail.md#efs-encryption-cloudtrail).
## Amazon EFS key policies for AWS KMS
Key policies are the primary way to control access to customer managed keys. For more information on key policies, see [Key policies in AWS KMS](https://docs.aws.amazon.com/kms/latest/developerguide/key-policies.html) in the *AWS Key Management Service Developer Guide. *The following list describes all the AWS KMS–related permissions that are required or otherwise supported by Amazon EFS for encrypted at rest file systems:
+ **kms:Encrypt** – (Optional) Encrypts plaintext into ciphertext. This permission is included in the default key policy.
+ **kms:Decrypt** – (Required) Decrypts ciphertext. Ciphertext is plaintext that has been previously encrypted. This permission is included in the default key policy.
+ **kms:ReEncrypt** – (Optional) Encrypts data on the server side with a new customer managed key, without exposing the plaintext of the data on the client side. The data is first decrypted and then re-encrypted. This permission is included in the default key policy.
+ **kms:GenerateDataKeyWithoutPlaintext** – (Required) Returns a data encryption key encrypted under a customer managed key. This permission is included in the default key policy under **kms:GenerateDataKey\$1**.
+ **kms:CreateGrant** – (Required) Adds a grant to a key to specify who can use the key and under what conditions. Grants are alternate permission mechanisms to key policies. For more information on grants, see [Grants in AWS KMS](https://docs.aws.amazon.com/kms/latest/developerguide/grants.html) in the *AWS Key Management Service Developer Guide.* This permission is included in the default key policy.
+ **kms:DescribeKey** – (Required) Provides detailed information about the specified customer managed key. This permission is included in the default key policy.
+ **kms:ListAliases** – (Optional) Lists all of the key aliases in the account. When you use the console to create an encrypted file system, this permission populates the **Select KMS key** list. We recommend using this permission to provide the best user experience. This permission is included in the default key policy.
### AWS managed key for Amazon EFS KMS policy
The KMS policy JSON for the AWS managed key for Amazon EFS, `aws/elasticfilesystem` is as follows:
```
{
"Version": "2012-10-17",
"Id": "auto-elasticfilesystem-1",
"Statement": [
{
"Sid": "Allow access to EFS for all principals in the account that are authorized to use EFS",
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": [
"kms:Encrypt",
"kms:Decrypt",
"kms:ReEncrypt*",
"kms:GenerateDataKey*",
"kms:CreateGrant",
"kms:DescribeKey"
],
"Resource": "*",
"Condition": {
"StringEquals": {
"kms:ViaService": "elasticfilesystem.us-east-2.amazonaws.com",
"kms:CallerAccount": "111122223333"
}
}
},
{
"Sid": "Allow direct access to key metadata to the account",
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::111122223333:root"
},
"Action": [
"kms:Describe*",
"kms:Get*",
"kms:List*",
"kms:RevokeGrant"
],
"Resource": "*"
}
]
}
```
## Key states and their effects
The state of your KMS key directly affects access to your encrypted file system:
Enabled
Normal operation - full read and write access to the file system
Disabled
File system becomes inaccessible after a brief period. Can be re-enabled.
Pending deletion
File system becomes inaccessible. Deletion can be canceled during the waiting period.
Deleted
File system permanently inaccessible. This action cannot be reversed.
**Warning**
If you disable or delete the KMS key used for your file system, or revoke Amazon EFS access to the key, your file system will become inaccessible. This can result in data loss if you don't have backups. Always ensure you have proper backup procedures in place before making changes to encryption keys.
# Troubleshooting encryption
**Topics**
+ [Mounting with encryption of data in transit fails](#mounting-tls-fails)
+ [Mounting with encryption of data in transit is interrupted](#mounting-tls-interrupt)
+ [Encrypted-at-rest file system can't be created](#unable-to-encrypt)
+ [Unusable encrypted file system](#unusable-encrypt)
## Mounting with encryption of data in transit fails
By default, when you use the Amazon EFS mount helper with Transport Layer Security (TLS), it enforces hostname checking. Some systems don't support this feature, such as when you use Red Hat Enterprise Linux or CentOS. In these cases, mounting an EFS file system using TLS fails.
**Action to take**
We recommend that you upgrade the version of stunnel on your client to support hostname checking. For more information, see [Upgrading `stunnel`](upgrading-stunnel.md).
## Mounting with encryption of data in transit is interrupted
It's possible, however unlikely, that your encrypted connection to your Amazon EFS file system can hang or be interrupted by client-side events.
**Action to take**
If your connection to your Amazon EFS file system with encryption of data in transit is interrupted, take the following steps:
1. Ensure that the stunnel service is running on the client.
1. Confirm that the watchdog application `amazon-efs-mount-watchdog` is running on the client. You can find out whether this application is running with the following command:
```
ps aux | grep [a]mazon-efs-mount-watchdog
```
1. Check your support logs. For more information, see [Getting support logs](mount-helper-logs.md).
1. Optionally, you can enable your stunnel logs and check the information in those as well. You can change the configuration of your logs in `/etc/amazon/efs/efs-utils.conf` to enable the stunnel logs. However, doing so requires unmounting and then remounting the file system with the mount helper for the changes to take effect.
**Important**
Enabling the stunnel logs can use up a nontrivial amount of space on your file system.
If the interruptions continue, contact AWS Support.
## Encrypted-at-rest file system can't be created
You've tried to create a new encrypted-at-rest file system. However, you get an error message saying that AWS KMS is unavailable.
**Action to take**
This error can occur in the rare case that AWS KMS becomes temporarily unavailable in your AWS Region. If this happens, wait until AWS KMS returns to full availability, and then try again to create the file system.
## Unusable encrypted file system
An encrypted file system consistently returns NFS server errors. These errors can occur when EFS can't retrieve your master key from AWS KMS for one of the following reasons:
+ The key was disabled.
+ The key was deleted.
+ Permission for Amazon EFS to use the key was revoked.
+ AWS KMS is temporarily unavailable.
**Action to take**
First, confirm that the AWS KMS key is enabled. You can do so by viewing the keys in the console. For more information, see [Viewing Keys](https://docs.aws.amazon.com/kms/latest/developerguide/viewing-keys.html) in the *AWS Key Management Service Developer Guide*.
If the key is not enabled, enable it. For more information, see [Enabling and Disabling Keys](https://docs.aws.amazon.com/kms/latest/developerguide/enabling-keys.html) in the *AWS Key Management Service Developer Guide*.
If the key is pending deletion, then this status disables the key. You can cancel the deletion, and re-enable the key. For more information, see [Scheduling and Canceling Key Deletion](https://docs.aws.amazon.com/kms/latest/developerguide/deleting-keys.html#deleting-keys-scheduling-key-deletion) in the *AWS Key Management Service Developer Guide*.
If the key is enabled, and you're still experiencing an issue, or if you encounter an issue re-enabling your key, contact AWS Support.
# Internetwork privacy
This topic describes how Amazon EFS secures connections from the service to other locations.
## Traffic between service and on-premises clients and applications
You have two connectivity options between your private network and AWS:
+ An AWS Site-to-Site VPN connection. For more information, see [What is AWS Site-to-Site VPN?](https://docs.aws.amazon.com/vpn/latest/s2svpn/VPC_VPN.html)
+ An Direct Connect connection. For more information, see [What is Direct Connect?](https://docs.aws.amazon.com/directconnect/latest/UserGuide/Welcome.html)
Access to Amazon EFS via the network is through AWS published APIs. Clients must support Transport Layer 1.2 or above. We recommend TLS 1.3 or above. Clients must also support cipher suites with Perfect Forward Secrecy (PFS), such as Ephemeral Diffie-Hellman (DHE) or Elliptic Curve Diffie-Hellman Ephemeral (ECDHE). Most modern systems such as Java 7 and later support these modes. Additionally, you must sign requests using an access key ID and a secret access key that are associated with an IAM principal, or you can use the [AWS Security Token Service (AWS STS)](https://docs.aws.amazon.com/STS/latest/APIReference/) to generate temporary security credentials to sign requests.
## Traffic between VPC and Amazon EFS API
To establish a private connection between your virtual private cloud (VPC) and the Amazon EFS API, you can create an interface VPC endpoint. You can use this connection to call the Amazon EFS API from your VPC without sending traffic over the internet. The endpoint provides secure connectivity to the Amazon EFS API without requiring an internet gateway, NAT instance, or virtual private network (VPN) connection. For more information, see [Working with interface VPC endpoints in Amazon EFS](efs-vpc-endpoints.md).
## Traffic between AWS resources in the same Region
An Amazon Virtual Private Cloud (Amazon VPC) endpoint for Amazon EFS is a logical entity within a VPC that allows connectivity only to Amazon EFS. The Amazon VPC routes requests to Amazon EFS and routes responses back to the VPC. For more information, see [VPC Endpoints](https://docs.aws.amazon.com/vpc/latest/userguide/vpc-endpoints.html) in the *Amazon VPC User Guide*.
# Identity and access management for Amazon EFS
AWS Identity and Access Management (IAM) is an AWS service that helps an administrator securely control access to AWS resources. IAM administrators control who can be *authenticated* (signed in) and *authorized* (have permissions) to use Amazon EFS resources. IAM is an AWS service that you can use with no additional charge.
**Topics**
+ [Audience](#security_iam_audience)
+ [Authenticating with identities](#security_iam_authentication)
+ [Managing access using policies](#security_iam_access-manage)
+ [How Amazon Elastic File System works with IAM](security_iam_service-with-iam.md)
+ [Identity-based policy examples for Amazon Elastic File System](security_iam_id-based-policy-examples.md)
+ [Resource-based policy examples for Amazon EFS](security_iam_resource-based-policy-examples.md)
+ [AWS managed policies for Amazon EFS](security-iam-awsmanpol.md)
+ [Using tags with Amazon EFS](using-tags-efs.md)
+ [Using service-linked roles for Amazon EFS](using-service-linked-roles.md)
+ [Troubleshooting Amazon Elastic File System identity and access](security_iam_troubleshoot.md)
## Audience
How you use AWS Identity and Access Management (IAM) differs based on your role:
+ **Service user** - request permissions from your administrator if you cannot access features (see [Troubleshooting Amazon Elastic File System identity and access](security_iam_troubleshoot.md))
+ **Service administrator** - determine user access and submit permission requests (see [How Amazon Elastic File System works with IAM](security_iam_service-with-iam.md))
+ **IAM administrator** - write policies to manage access (see [Identity-based policy examples for Amazon Elastic File System](security_iam_id-based-policy-examples.md))
## Authenticating with identities
Authentication is how you sign in to AWS using your identity credentials. You must be authenticated as the AWS account root user, an IAM user, or by assuming an IAM role.
You can sign in as a federated identity using credentials from an identity source like AWS IAM Identity Center (IAM Identity Center), single sign-on authentication, or Google/Facebook credentials. For more information about signing in, see [How to sign in to your AWS account](https://docs.aws.amazon.com/signin/latest/userguide/how-to-sign-in.html) in the *AWS Sign-In User Guide*.
For programmatic access, AWS provides an SDK and CLI to cryptographically sign requests. For more information, see [AWS Signature Version 4 for API requests](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_sigv.html) in the *IAM User Guide*.
### AWS account root user
When you create an AWS account, you begin with one sign-in identity called the AWS account *root user* that has complete access to all AWS services and resources. We strongly recommend that you don't use the root user for everyday tasks. For tasks that require root user credentials, see [Tasks that require root user credentials](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_root-user.html#root-user-tasks) in the *IAM User Guide*.
### Federated identity
As a best practice, require human users to use federation with an identity provider to access AWS services using temporary credentials.
A *federated identity* is a user from your enterprise directory, web identity provider, or Directory Service that accesses AWS services using credentials from an identity source. Federated identities assume roles that provide temporary credentials.
For centralized access management, we recommend AWS IAM Identity Center. For more information, see [What is IAM Identity Center?](https://docs.aws.amazon.com/singlesignon/latest/userguide/what-is.html) in the *AWS IAM Identity Center User Guide*.
### IAM users and groups
An *[IAM user](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_users.html)* is an identity with specific permissions for a single person or application. We recommend using temporary credentials instead of IAM users with long-term credentials. For more information, see [Require human users to use federation with an identity provider to access AWS using temporary credentials](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html#bp-users-federation-idp) in the *IAM User Guide*.
An [https://docs.aws.amazon.com/IAM/latest/UserGuide/id_groups.html](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_groups.html) specifies a collection of IAM users and makes permissions easier to manage for large sets of users. For more information, see [Use cases for IAM users](https://docs.aws.amazon.com/IAM/latest/UserGuide/gs-identities-iam-users.html) in the *IAM User Guide*.
### IAM roles
An *[IAM role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html)* is an identity with specific permissions that provides temporary credentials. You can assume a role by [switching from a user to an IAM role (console)](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_use_switch-role-console.html) or by calling an AWS CLI or AWS API operation. For more information, see [Methods to assume a role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_manage-assume.html) in the *IAM User Guide*.
IAM roles are useful for federated user access, temporary IAM user permissions, cross-account access, cross-service access, and applications running on Amazon EC2. For more information, see [Cross account resource access in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies-cross-account-resource-access.html) in the *IAM User Guide*.
## Managing access using policies
You control access in AWS by creating policies and attaching them to AWS identities or resources. A policy defines permissions when associated with an identity or resource. AWS evaluates these policies when a principal makes a request. Most policies are stored in AWS as JSON documents. For more information about JSON policy documents, see [Overview of JSON policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html#access_policies-json) in the *IAM User Guide*.
Using policies, administrators specify who has access to what by defining which **principal** can perform **actions** on what **resources**, and under what **conditions**.
By default, users and roles have no permissions. An IAM administrator creates IAM policies and adds them to roles, which users can then assume. IAM policies define permissions regardless of the method used to perform the operation.
### Identity-based policies
Identity-based policies are JSON permissions policy documents that you attach to an identity (user, group, or role). These policies control what actions identities can perform, on which resources, and under what conditions. To learn how to create an identity-based policy, see [Define custom IAM permissions with customer managed policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_create.html) in the *IAM User Guide*.
Identity-based policies can be *inline policies* (embedded directly into a single identity) or *managed policies* (standalone policies attached to multiple identities). To learn how to choose between managed and inline policies, see [Choose between managed policies and inline policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies-choosing-managed-or-inline.html) in the *IAM User Guide*.
### Resource-based policies
Resource-based policies are JSON policy documents that you attach to a resource. Examples include IAM *role trust policies* and Amazon S3 *bucket policies*. In services that support resource-based policies, service administrators can use them to control access to a specific resource. You must [specify a principal](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html) in a resource-based policy.
Resource-based policies are inline policies that are located in that service. You can't use AWS managed policies from IAM in a resource-based policy.
### Other policy types
AWS supports additional policy types that can set the maximum permissions granted by more common policy types:
+ **Permissions boundaries** – Set the maximum permissions that an identity-based policy can grant to an IAM entity. For more information, see [Permissions boundaries for IAM entities](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_boundaries.html) in the *IAM User Guide*.
+ **Service control policies (SCPs)** – Specify the maximum permissions for an organization or organizational unit in AWS Organizations. For more information, see [Service control policies](https://docs.aws.amazon.com/organizations/latest/userguide/orgs_manage_policies_scps.html) in the *AWS Organizations User Guide*.
+ **Resource control policies (RCPs)** – Set the maximum available permissions for resources in your accounts. For more information, see [Resource control policies (RCPs)](https://docs.aws.amazon.com/organizations/latest/userguide/orgs_manage_policies_rcps.html) in the *AWS Organizations User Guide*.
+ **Session policies** – Advanced policies passed as a parameter when creating a temporary session for a role or federated user. For more information, see [Session policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html#policies_session) in the *IAM User Guide*.
### Multiple policy types
When multiple types of policies apply to a request, the resulting permissions are more complicated to understand. To learn how AWS determines whether to allow a request when multiple policy types are involved, see [Policy evaluation logic](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_evaluation-logic.html) in the *IAM User Guide*.
# How Amazon Elastic File System works with IAM
Before you use IAM to manage access to Amazon EFS, learn what IAM features are available to use with Amazon EFS.
**IAM features you can use with Amazon Elastic File System**
| IAM feature | Amazon EFS support |
| --- | --- |
| [Identity-based policies](#security_iam_service-with-iam-id-based-policies) | Yes |
| [Resource-based policies](#security_iam_service-with-iam-resource-based-policies) | Yes |
| [Policy actions](#security_iam_service-with-iam-id-based-policies-actions) | Yes |
| [Policy resources](#security_iam_service-with-iam-id-based-policies-resources) | Yes |
| [Policy condition keys (service-specific)](#security_iam_service-with-iam-id-based-policies-conditionkeys) | Yes |
| [ACLs](#security_iam_service-with-iam-acls) | No |
| [ABAC (tags in policies)](#security_iam_service-with-iam-tags) | Partial |
| [Temporary credentials](#security_iam_service-with-iam-roles-tempcreds) | Yes |
| [Principal permissions](#security_iam_service-with-iam-principal-permissions) | Yes |
| [Service roles](#security_iam_service-with-iam-roles-service) | Yes |
| [Service-linked roles](#security_iam_service-with-iam-roles-service-linked) | Yes |
To get a high-level view of how Amazon EFS and other AWS services work with most IAM features, see [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) in the *IAM User Guide*.
## Identity-based policies for Amazon EFS
**Supports identity-based policies:** Yes
Identity-based policies are JSON permissions policy documents that you can attach to an identity, such as an IAM user, group of users, or role. These policies control what actions users and roles can perform, on which resources, and under what conditions. To learn how to create an identity-based policy, see [Define custom IAM permissions with customer managed policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_create.html) in the *IAM User Guide*.
With IAM identity-based policies, you can specify allowed or denied actions and resources as well as the conditions under which actions are allowed or denied. To learn about all of the elements that you can use in a JSON policy, see [IAM JSON policy elements reference](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements.html) in the *IAM User Guide*.
### Identity-based policy examples for Amazon EFS
To view examples of Amazon EFS identity-based policies, see [Identity-based policy examples for Amazon Elastic File System](security_iam_id-based-policy-examples.md).
## Resource-based policies within Amazon EFS
**Supports resource-based policies:** Yes
Resource-based policies are JSON policy documents that you attach to a resource. Examples of resource-based policies are IAM *role trust policies* and Amazon S3 *bucket policies*. In services that support resource-based policies, service administrators can use them to control access to a specific resource. For the resource where the policy is attached, the policy defines what actions a specified principal can perform on that resource and under what conditions. You must [specify a principal](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html) in a resource-based policy. Principals can include accounts, users, roles, federated users, or AWS services.
To enable cross-account access, you can specify an entire account or IAM entities in another account as the principal in a resource-based policy. For more information, see [Cross account resource access in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies-cross-account-resource-access.html) in the *IAM User Guide*.
To learn about using a resource policy to control file system data access, see [Using IAM to control access to file systems](iam-access-control-nfs-efs.md). To learn how to attach a resource-based policy to a file system, see [Creating file system policies](create-file-system-policy.md).
### Resource-based policy examples within Amazon EFS
To view examples of Amazon EFS resource-based policies, see [Resource-based policy examples for Amazon EFS](security_iam_resource-based-policy-examples.md).
## Policy actions for Amazon EFS
**Supports policy actions:** Yes
Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.
The `Action` element of a JSON policy describes the actions that you can use to allow or deny access in a policy. Include actions in a policy to grant permissions to perform the associated operation.
To see a list of Amazon EFS actions, see [Actions defined by Amazon Elastic File System](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonelasticfilesystem.html#amazonelasticfilesystem-actions-as-permissions) in the *Service Authorization Reference*.
Policy actions in Amazon EFS use the following prefix before the action:
```
elasticfilesystem
```
To specify multiple actions in a single statement, separate them with commas.
```
"Action": [
"elasticfilesystem:action1",
"elasticfilesystem:action2"
]
```
To view examples of Amazon EFS identity-based policies, see [Identity-based policy examples for Amazon Elastic File System](security_iam_id-based-policy-examples.md).
## Policy resources for Amazon EFS
**Supports policy resources:** Yes
Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.
The `Resource` JSON policy element specifies the object or objects to which the action applies. As a best practice, specify a resource using its [Amazon Resource Name (ARN)](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference-arns.html). For actions that don't support resource-level permissions, use a wildcard (\$1) to indicate that the statement applies to all resources.
```
"Resource": "*"
```
To see a list of Amazon EFS resource types and their ARNs, see [Resources defined by Amazon Elastic File System](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonelasticfilesystem.html#amazonelasticfilesystem-resources-for-iam-policies) in the *Service Authorization Reference*. To learn with which actions you can specify the ARN of each resource, see [Actions defined by Amazon Elastic File System](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonelasticfilesystem.html#amazonelasticfilesystem-actions-as-permissions).
To view examples of Amazon EFS identity-based policies, see [Identity-based policy examples for Amazon Elastic File System](security_iam_id-based-policy-examples.md).
## Policy condition keys for Amazon EFS
**Supports service-specific policy condition keys:** Yes
Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.
The `Condition` element specifies when statements execute based on defined criteria. You can create conditional expressions that use [condition operators](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition_operators.html), such as equals or less than, to match the condition in the policy with values in the request. To see all AWS global condition keys, see [AWS global condition context keys](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_condition-keys.html) in the *IAM User Guide*.
To see a list of Amazon EFS condition keys, see [Condition keys for Amazon Elastic File System](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonelasticfilesystem.html#amazonelasticfilesystem-policy-keys) in the *Service Authorization Reference*. To learn with which actions and resources you can use a condition key, see [Actions defined by Amazon Elastic File System](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonelasticfilesystem.html#amazonelasticfilesystem-actions-as-permissions).
To view examples of Amazon EFS identity-based policies, see [Identity-based policy examples for Amazon Elastic File System](security_iam_id-based-policy-examples.md).
## ACLs in Amazon EFS
**Supports ACLs:** No
Access control lists (ACLs) control which principals (account members, users, or roles) have permissions to access a resource. ACLs are similar to resource-based policies, although they do not use the JSON policy document format.
## ABAC with Amazon EFS
**Supports ABAC (tags in policies):** Partial
Attribute-based access control (ABAC) is an authorization strategy that defines permissions based on attributes called tags. You can attach tags to IAM entities and AWS resources, then design ABAC policies to allow operations when the principal's tag matches the tag on the resource.
To control access based on tags, you provide tag information in the [condition element](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition.html) of a policy using the `aws:ResourceTag/key-name`, `aws:RequestTag/key-name`, or `aws:TagKeys` condition keys.
If a service supports all three condition keys for every resource type, then the value is **Yes** for the service. If a service supports all three condition keys for only some resource types, then the value is **Partial**.
For more information about ABAC, see [Define permissions with ABAC authorization](https://docs.aws.amazon.com/IAM/latest/UserGuide/introduction_attribute-based-access-control.html) in the *IAM User Guide*. To view a tutorial with steps for setting up ABAC, see [Use attribute-based access control (ABAC)](https://docs.aws.amazon.com/IAM/latest/UserGuide/tutorial_attribute-based-access-control.html) in the *IAM User Guide*.
## Using temporary credentials with Amazon EFS
**Supports temporary credentials:** Yes
Temporary credentials provide short-term access to AWS resources and are automatically created when you use federation or switch roles. AWS recommends that you dynamically generate temporary credentials instead of using long-term access keys. For more information, see [Temporary security credentials in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp.html) and [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) in the *IAM User Guide*.
## Cross-service principal permissions for Amazon EFS
**Supports forward access sessions (FAS):** Yes
Forward access sessions (FAS) use the permissions of the principal calling an AWS service, combined with the requesting AWS service to make requests to downstream services. For policy details when making FAS requests, see [Forward access sessions](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_forward_access_sessions.html).
## Service roles for Amazon EFS
**Supports service roles:** Yes
A service role is an [IAM role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html) that a service assumes to perform actions on your behalf. An IAM administrator can create, modify, and delete a service role from within IAM. For more information, see [Create a role to delegate permissions to an AWS service](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-service.html) in the *IAM User Guide*.
**Warning**
Changing the permissions for a service role might break Amazon EFS functionality. Edit service roles only when Amazon EFS provides guidance to do so.
## Service-linked roles for Amazon EFS
**Supports service-linked roles:** Yes
A service-linked role is a type of service role that is linked to an AWS service. The service can assume the role to perform an action on your behalf. Service-linked roles appear in your AWS account and are owned by the service. An IAM administrator can view, but not edit the permissions for service-linked roles.
For details about creating or managing Amazon EFS service-linked roles, see [Using service-linked roles for Amazon EFS](using-service-linked-roles.md).
# Identity-based policy examples for Amazon Elastic File System
By default, users and roles don't have permission to create or modify Amazon EFS resources. To grant users permission to perform actions on the resources that they need, an IAM administrator can create IAM policies.
To learn how to create an IAM identity-based policy by using these example JSON policy documents, see [Create IAM policies (console)](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_create-console.html) in the *IAM User Guide*.
For details about actions and resource types defined by Amazon EFS, including the format of the ARNs for each of the resource types, see [Actions, resources, and condition keys for Amazon Elastic File System](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonelasticfilesystem.html) in the *Service Authorization Reference*.
**Topics**
+ [Policy best practices](#security_iam_service-with-iam-policy-best-practices)
+ [Using the Amazon EFS console](#security_iam_id-based-policy-examples-console)
+ [Example: Allow users to view their own permissions](#security_iam_id-based-policy-examples-view-own-permissions)
+ [Example: Enforce the creation of encrypted file systems](#using-iam-to-enforce-encryption-at-rest)
+ [Example: Enforce the creation of unencrypted file systems](#using-iam-to-enforce-unencrypted-file-systems)
## Policy best practices
Identity-based policies determine whether someone can create, access, or delete Amazon EFS resources in your account. These actions can incur costs for your AWS account. When you create or edit identity-based policies, follow these guidelines and recommendations:
+ **Get started with AWS managed policies and move toward least-privilege permissions** – To get started granting permissions to your users and workloads, use the *AWS managed policies* that grant permissions for many common use cases. They are available in your AWS account. We recommend that you reduce permissions further by defining AWS customer managed policies that are specific to your use cases. For more information, see [AWS managed policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_managed-vs-inline.html#aws-managed-policies) or [AWS managed policies for job functions](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_job-functions.html) in the *IAM User Guide*.
+ **Apply least-privilege permissions** – When you set permissions with IAM policies, grant only the permissions required to perform a task. You do this by defining the actions that can be taken on specific resources under specific conditions, also known as *least-privilege permissions*. For more information about using IAM to apply permissions, see [ Policies and permissions in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies.html) in the *IAM User Guide*.
+ **Use conditions in IAM policies to further restrict access** – You can add a condition to your policies to limit access to actions and resources. For example, you can write a policy condition to specify that all requests must be sent using SSL. You can also use conditions to grant access to service actions if they are used through a specific AWS service, such as CloudFormation. For more information, see [ IAM JSON policy elements: Condition](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition.html) in the *IAM User Guide*.
+ **Use IAM Access Analyzer to validate your IAM policies to ensure secure and functional permissions** – IAM Access Analyzer validates new and existing policies so that the policies adhere to the IAM policy language (JSON) and IAM best practices. IAM Access Analyzer provides more than 100 policy checks and actionable recommendations to help you author secure and functional policies. For more information, see [Validate policies with IAM Access Analyzer](https://docs.aws.amazon.com/IAM/latest/UserGuide/access-analyzer-policy-validation.html) in the *IAM User Guide*.
+ **Require multi-factor authentication (MFA)** – If you have a scenario that requires IAM users or a root user in your AWS account, turn on MFA for additional security. To require MFA when API operations are called, add MFA conditions to your policies. For more information, see [ Secure API access with MFA](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_mfa_configure-api-require.html) in the *IAM User Guide*.
For more information about best practices in IAM, see [Security best practices in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html) in the *IAM User Guide*.
## Using the Amazon EFS console
To access the Amazon Elastic File System console, you must have a minimum set of permissions. These permissions must allow you to list and view details about the Amazon EFS resources in your AWS account. If you create an identity-based policy that is more restrictive than the minimum required permissions, the console won't function as intended for entities (users or roles) with that policy.
You don't need to allow minimum console permissions for users that are making calls only to the AWS CLI or the AWS API. Instead, allow access to only the actions that match the API operation that they're trying to perform.
To ensure that users and roles can still use the Amazon EFS console, also attach the Amazon EFS `AmazonElasticFileSystemReadOnlyAccess` AWS managed policy to the entities. For more information, see [Adding permissions to a user](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_users_change-permissions.html#users_change_permissions-add-console) in the *IAM User Guide*.
You can see the `AmazonElasticFileSystemReadOnlyAccess` and other Amazon EFS managed service policies in [AWS managed policies for Amazon EFS](security-iam-awsmanpol.md).
## Example: Allow users to view their own permissions
This example shows how you might create a policy that allows IAM users to view the inline and managed policies that are attached to their user identity. This policy includes permissions to complete this action on the console or programmatically using the AWS CLI or AWS API.
```
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "ViewOwnUserInfo",
"Effect": "Allow",
"Action": [
"iam:GetUserPolicy",
"iam:ListGroupsForUser",
"iam:ListAttachedUserPolicies",
"iam:ListUserPolicies",
"iam:GetUser"
],
"Resource": ["arn:aws:iam::*:user/${aws:username}"]
},
{
"Sid": "NavigateInConsole",
"Effect": "Allow",
"Action": [
"iam:GetGroupPolicy",
"iam:GetPolicyVersion",
"iam:GetPolicy",
"iam:ListAttachedGroupPolicies",
"iam:ListGroupPolicies",
"iam:ListPolicyVersions",
"iam:ListPolicies",
"iam:ListUsers"
],
"Resource": "*"
}
]
}
```
## Example: Enforce the creation of encrypted file systems
The following example illustrates an identity-based policy that authorizes principals to create only encrypted file systems.
```
{
"Statement": [
{
"Effect": "Allow",
"Action": "elasticfilesystem:CreateFileSystem",
"Condition": {
"Bool": {
"elasticfilesystem:Encrypted": "true"
}
},
"Resource": "*"
}
]
}
```
If this policy is assigned to a user who tries to create an unencrypted file system, the request fails. The user sees a message similar to the following, whether they are using the AWS Management Console, the AWS CLI, or the AWS API or SDK:
```
User: arn:aws:iam::111122223333:user/username is not authorized to
perform: elasticfilesystem:CreateFileSystem on the specified resource.
```
## Example: Enforce the creation of unencrypted file systems
The following example illustrates an identity-based policy that authorizes principals to create only unencrypted file systems.
```
{
"Statement": [
{
"Effect": "Allow",
"Action": "elasticfilesystem:CreateFileSystem",
"Condition": {
"Bool": {
"elasticfilesystem:Encrypted": "false"
}
},
"Resource": "*"
}
]
}
```
If this policy is assigned to a user who tries to create an encrypted file system, the request fails. The user sees a message similar to the following, whether they are using the AWS Management Console, the AWS CLI, or the AWS API or SDK:
```
User: arn:aws:iam::111122223333:user/username is not authorized to
perform: elasticfilesystem:CreateFileSystem on the specified resource.
```
You can also enforce the creation of encrypted or unencrypted EFS file systems by creating an AWS Organizations service control policy (SCP). For more information about service control policies in AWS Organizations, see [Service control policies](https://docs.aws.amazon.com/organizations/latest/userguide/orgs_manage_policies_scps.html#orgs_manage_policies_scp) in the *AWS Organizations User Guide*.
# Resource-based policy examples for Amazon EFS
In this section, you can find example file system policies that grant or deny permissions for various Amazon EFS actions. EFS file system policies have a 20,000 character limit. For information about the elements of a resource-based policy, see [Resource-based policies within Amazon EFS](security_iam_service-with-iam.md#security_iam_service-with-iam-resource-based-policies).
**Important**
If you grant permission to an individual IAM user or role in a file system policy, don't delete or recreate that user or role while the policy is in effect on the file system. If this happens, that user or role is effectively locked out from file system and will not be able to access it. For more information, see [Specifying a Principal](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html#Principal_specifying) in the *IAM User Guide*.
For information about how to create a file system policy, see [Creating file system policies](create-file-system-policy.md).
**Topics**
+ [Example: Grant read and write access to a specific AWS role](#file-sys-policy-readonly)
+ [Example: Grant read-only access](#file-sys-policy-readonly)
+ [Example: Grant access to an EFS access point](#file-sys-policy-accessprofile-efs)
## Example: Grant read and write access to a specific AWS role
In this example, the EFS file system policy has the following characteristics:
+ The effect is `Allow`.
+ The principal is set to the Testing\$1Role in the AWS account.
+ The action is set to `ClientMount` (read), and `ClientWrite`.
+ The condition for granting permissions is set to `AccessedViaMountTarget`.
```
{
"Statement": [
{
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::111122223333:role/Testing_Role"
},
"Action": [
"elasticfilesystem:ClientWrite",
"elasticfilesystem:ClientMount"
],
"Resource": "arn:aws:elasticfilesystem:us-east-2:111122223333:file-system/fs-1234abcd",
"Condition": {
"Bool": {
"elasticfilesystem:AccessedViaMountTarget": "true"
}
}
}
]
}
```
## Example: Grant read-only access
The following file system policy only grants `ClientMount`, or read-only, permissions to the `EfsReadOnly` IAM role.
```
{
"Id": "read-only-example-policy02",
"Statement": [
{
"Sid": "efs-statement-example02",
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::111122223333:role/EfsReadOnly"
},
"Action": [
"elasticfilesystem:ClientMount"
],
"Resource": "arn:aws:elasticfilesystem:us-east-2:111122223333:file-system/fs-12345678"
}
]
}
```
To learn how to set additional file system policies, including denying root access to all IAM principals, except for a specific management workstation, see [Enable root squashing using IAM authorization for NFS clients](accessing-fs-nfs-permissions.md#enable-root-squashing).
## Example: Grant access to an EFS access point
You use an EFS access policy to provide an NFS client with an application-specific view into shared file-based datasets on an EFS file system. You grant the access point permissions on the file system using a file system policy.
This file policy example uses a condition element to grant a specific access point that is identified by its ARN full access to the file system.
For more information about using EFS access points, see [Working with access points](efs-access-points.md).
```
{
"Id": "access-point-example03",
"Statement": [
{
"Sid": "access-point-statement-example03",
"Effect": "Allow",
"Principal": {"AWS": "arn:aws:iam::555555555555:role/EfsAccessPointFullAccess"},
"Action": "elasticfilesystem:Client*",
"Resource": "arn:aws:elasticfilesystem:us-east-2:111122223333:file-system/fs-12345678",
"Condition": {
"StringEquals": {
"elasticfilesystem:AccessPointArn":"arn:aws:elasticfilesystem:us-east-2:555555555555:access-point/fsap-12345678" }
}
}
]
}
```
# AWS managed policies for Amazon EFS
An AWS managed policy is a standalone policy that is created and administered by AWS. AWS managed policies are designed to provide permissions for many common use cases so that you can start assigning permissions to users, groups, and roles.
Keep in mind that AWS managed policies might not grant least-privilege permissions for your specific use cases because they're available for all AWS customers to use. We recommend that you reduce permissions further by defining [ customer managed policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_managed-vs-inline.html#customer-managed-policies) that are specific to your use cases.
You cannot change the permissions defined in AWS managed policies. If AWS updates the permissions defined in an AWS managed policy, the update affects all principal identities (users, groups, and roles) that the policy is attached to. AWS is most likely to update an AWS managed policy when a new AWS service is launched or new API operations become available for existing services.
For more information, see [AWS managed policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_managed-vs-inline.html#aws-managed-policies) in the *IAM User Guide*.
## AWS managed policy: AWSServiceRoleForAmazonElasticFileSystem
Amazon EFS uses the service-linked role named `AWSServiceRoleForAmazonElasticFileSystem` to allow Amazon EFS to manage AWS resources on your behalf. This role trusts the `elasticfilesystem.amazonaws.com` service to assume the role. For more information, see [Using service-linked roles for Amazon EFS](using-service-linked-roles.md).
## AWS managed policy: AmazonElasticFileSystemFullAccess
You can attach the `AmazonElasticFileSystemFullAccess` policy to your IAM identities.
This policy grants administrative permissions that allow full access to Amazon EFS and access to related AWS services via the AWS Management Console.
**Permissions details**
This policy includes the following permissions.
+ `elasticfilesystem` – Allows principals to perform all actions in the Amazon EFS console. It also allows principals to create (`elasticfilesystem:Backup`) and restore (`elasticfilesystem:Restore`) backups using AWS Backup.
+ `cloudwatch` – Allows principals to describe Amazon CloudWatch file system metrics and alarms for a metric in the Amazon EFS console.
+ `ec2` – Allows principals to create, delete, and describe network interfaces, describe and modify network interface attributes, describe Availability Zones, security groups, subnets, virtual private clouds (VPCs) and VPC attributes associated with an EFS file system in the Amazon EFS console.
+ `kms` – Allows principals to list aliases for AWS Key Management Service (AWS KMS) keys and to describe KMS keys in the Amazon EFS console.
+ `iam` – Grants permission to create a service linked role that allows Amazon EFS to manage AWS resources on the user's behalf.
+ `iam:PassRole` – Grants permission to pass an IAM role to Amazon EFS.
To view the permissions for this policy, see [https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemFullAccess.html](https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemFullAccess.html) in the *AWS Managed Policy Reference Guide*.
## AWS managed policy: AmazonElasticFileSystemReadOnlyAccess
You can attach the `AmazonElasticFileSystemReadOnlyAccess` policy to your IAM identities.
This policy grants read only access to Amazon EFS via the AWS Management Console.
**Permissions details**
This policy includes the following permissions.
+ `elasticfilesystem` – Allows principals to describe attributes of Amazon EFS file systems, including account preferences, backup and file system policies, lifecycle configuration, mount targets and their security groups, tags, and access points in the Amazon EFS console.
+ `cloudwatch` – Allows principals to retrieve CloudWatch metrics and describe alarms for metrics in the Amazon EFS console.
+ `ec2` – Allows principals to view Availability Zones, network interfaces and their attributes, security groups, subnets, VPCs and their attributes in the Amazon EFS console.
+ `kms` – Allows principals to list aliases for AWS KMS keys in the Amazon EFS console.
To view the permissions for this policy, see [https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemReadOnlyAccess.html](https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemReadOnlyAccess.html) in the *AWS Managed Policy Reference Guide*.
## AWS managed policy: AmazonElasticFileSystemClientFullAccess
You can attach the `AmazonElasticFileSystemClientFullAccess` policy to an IAM entity.
This policy grants read and write client access to EFS file systems. This policy allows NFS clients to mount, read and write to EFS file systems.
To view the permissions for this policy, see [https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemClientFullAccess.html](https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemClientFullAccess.html) in the *AWS Managed Policy Reference Guide*.
## AWS managed policy: AmazonElasticFileSystemClientReadWriteAccess
You can attach the `AmazonElasticFileSystemClientReadWriteAccess` policy to an IAM entity.
This policy grants read and write client access to EFS file systems. This policy allows NFS clients to mount, read and write to EFS file systems.
To view the permissions for this policy, see [https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemClientReadWriteAccess.html](https://docs.aws.amazon.com/aws-managed-policy/latest/reference/AmazonElasticFileSystemClientReadWriteAccess.html) in the *AWS Managed Policy Reference Guide*.
## Amazon EFS updates to AWS managed policies
View details about updates to AWS managed policies for Amazon EFS since this service began tracking these changes. For automatic alerts about changes to this page, subscribe to the RSS feed on the Amazon EFS [Document history](document-history.md) page.
| Change | Description | Date |
| --- | --- | --- |
| Update to an existing policy | Policy: [AmazonElasticFileSystemFullAccess](#security-iam-awsmanpol-AmazonElasticFileSystemFullAccess) Amazon EFS added the following: [\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/efs/latest/ug/security-iam-awsmanpol.html) | November 7, 2024 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemServiceRolePolicy](using-service-linked-roles.md#slr-permissions) Amazon EFS added `ReplicationRead` and `ReplicationWrite` to give permission to read and write file system data for replication. | November 7, 2024 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemReadOnlyAccess](#security-iam-awsmanpol-AmazonElasticFileSystemReadOnlyAccess) Amazon EFS added the `ReplicationRead` action to give permission to read file system data for replication. | November 7, 2024 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemReadOnlyAccess](#security-iam-awsmanpol-AmazonElasticFileSystemReadOnlyAccess) Amazon EFS added new permissions that give source and destination accounts access to file systems for cross-account replications. | August 7, 2024 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemFullAccess](#security-iam-awsmanpol-AmazonElasticFileSystemFullAccess)Amazon EFS added a new permission to allow principals to disable and enable protection on a file system. The permissions are required to allow Amazon EFS to replicate to an existing file system. | November 27, 2023 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemServiceRolePolicy](using-service-linked-roles.md#slr-permissions) Amazon EFS added new permissions to allow principals to create, describe, and delete Amazon EFS replications, and to create Amazon EFS file systems. The permissions are required to allow Amazon EFS to manage files system replication configurations on the user's behalf. | January 25, 2022 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemReadOnlyAccess](#security-iam-awsmanpol-AmazonElasticFileSystemReadOnlyAccess) Amazon EFS added a new permission to allow principals to describe Amazon EFS replications. The permissions are required to allow users to view files system replication configurations. | January 25, 2022 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemFullAccess](#security-iam-awsmanpol-AmazonElasticFileSystemFullAccess) Amazon EFS added new permissions to allow principals to create, describe, and delete Amazon EFS replications. The permissions are required to allow users to manage files system replication configurations. | January 25, 2022 |
| Started tracking policy | Policy: [AmazonElasticFileSystemClientReadWriteAccess](#security-iam-awsmanpol-AmazonElasticFileSystemClientReadWriteAccess) Grants read and write privileges on Amazon EFS file systems to NFS clients. | January 3, 2022 |
| Started tracking policy | Policy: [AmazonElasticFileSystemServiceRolePolicy](using-service-linked-roles.md#slr-permissions)The service-linked role permissions for Amazon EFS. | October 8, 2021 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemFullAccess](#security-iam-awsmanpol-AmazonElasticFileSystemFullAccess) Amazon EFS added new permissions to allow principals to modify and describe Amazon EFS account preferences. The permissions are required to allow users to view and set account preferences settings in the Amazon EFS console. | May 7, 2021 |
| Update to an existing policy | Policy: [AmazonElasticFileSystemReadOnlyAccess](#security-iam-awsmanpol-AmazonElasticFileSystemReadOnlyAccess) Amazon EFS added new permissions to allow principals to describe Amazon EFS account preferences. The permissions are required to allow users to view account preferences settings in the Amazon EFS console. | May 7, 2021 |
| Amazon EFS started tracking changes | Amazon EFS started tracking changes for its AWS managed policies. | May 7, 2021 |
# Using tags with Amazon EFS
You can use tags to control access to Amazon EFS resources and to implement attribute-based access control (ABAC). For more information, see:
+ [Tagging EFS resources](manage-fs-tags.md)
+ [Controlling access based on tags on a resource](#resource-tag-control)
+ [What is ABAC for AWS?](https://docs.aws.amazon.com/IAM/latest/UserGuide/introduction_attribute-based-access-control.html) in the *IAM User Guide*
**Note**
Amazon EFS replication does not support using tags for attribute-based access control (ABAC).
To apply tags to Amazon EFS resources during creation, users must have certain AWS Identity and Access Management (IAM) permissions.
## Granting permissions to tag resources during creation
The following tag-on create Amazon EFS API actions allow you to specify tags when you create the resource.
+ `CreateAccessPoint`
+ `CreateFileSystem`
To enable users to tag resources on creation, they must have permissions to use the action that creates the resources, such as `elasticfilesystem:CreateAccessPoint` or `elasticfilesystem:CreateFileSystem`. If tags are specified in the resource-creating action, AWS performs additional authorization on the `elasticfilesystem:TagResource` action to verify if users have permission to create tags. Therefore, users must also have explicit permissions to use the `elasticfilesystem:TagResource` action.
In the IAM policy definition for the `elasticfilesystem:TagResource` action, use the `Condition` element with the `elasticfilesystem:CreateAction` condition key to give tagging permissions to the action that creates the resource.
**Example policy: Allow adding tags to file systems only at the time of creation**
The following example policy allows users to create file systems and apply tags to them only during creation. Users are not permitted to tag any existing resources (they cannot call the `elasticfilesystem:TagResource` action directly).
```
{
"Statement": [
{
"Effect": "Allow",
"Action": [
"elasticfilesystem:CreateFileSystem"
],
"Resource": "arn:aws:elasticfilesystem:region:account-id:file-system/*"
},
{
"Effect": "Allow",
"Action": [
"elasticfilesystem:TagResource"
],
"Resource": "arn:aws:elasticfilesystem:region:account-id:file-system/*",
"Condition": {
"StringEquals": {
"elasticfilesystem:CreateAction": "CreateFileSystem"
}
}
}
]
}
```
## Using tags to control access to your Amazon EFS resources
To control access to Amazon EFS resources and actions, you can use IAM policies based on tags. You can provide this control in two ways:
+ You can control access to Amazon EFS resources based on the tags on those resources.
+ You can control which tags can be passed in an IAM request condition.
For information about how to use tags to control access to AWS resources, see [Controlling access using tags](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_tags.html) in the *IAM User Guide*.
## Controlling access based on tags on a resource
To control which actions a user or role can perform on an Amazon EFS resource, you can use tags on the resource. For example, you might want to allow or deny specific API operations on a file system resource based on the key-value pair of the tag on the resource.
**Example policy: Create a file system only when a specific tag is used**
The following example policy allows the user to create a file system only when they tag it with a specific tag key-value pair, in this example, `key=Department`, `value=Finance`.
```
{
"Effect": "Allow",
"Action": [
"elasticfilesystem:CreateFileSystem",
"elasticfilesystem:TagResource"
],
"Resource": "arn:aws:elasticfilesystem:region:account-id:file-system/*",
"Condition": {
"StringEquals": {
"aws:RequestTag/Department": "Finance"
}
}
}
```
**Example policy: Delete file systems with specific tags**
The following example policy allows a user to delete only file systems that are tagged with `Department=Finance`.
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"elasticfilesystem:DeleteFileSystem"
],
"Resource": "arn:aws:elasticfilesystem:us-east-1:111122223333:file-system/*",
"Condition": {
"StringEquals": {
"aws:ResourceTag/Department": "Finance"
}
}
}
]
}
```
------
# Using service-linked roles for Amazon EFS
Amazon EFS uses an AWS Identity and Access Management (IAM)[ service-linked role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_terms-and-concepts.html#iam-term-service-linked-role). The Amazon EFS service-linked role is a unique type of IAM role that is linked directly to Amazon EFS. The predefined Amazon EFS service-linked role includes permissions that the service requires to call other AWS services on your behalf.
A service-linked role makes setting up Amazon EFS easier because you don't have to manually add the necessary permissions. Amazon EFS defines the permissions of its service-linked role, and only Amazon EFS can assume its role. The defined permissions include the trust policy and the permissions policy, and that permissions policy can't be attached to any other IAM entity.
You can delete the Amazon EFS service-linked role only after first deleting your Amazon EFS file systems. This protects your Amazon EFS resources because you can't inadvertently remove permission to access the resources.
The service-linked role enables all API calls to be visible through AWS CloudTrail. This helps with monitoring and auditing requirements because you can track all actions that Amazon EFS performs on your behalf. For more information, see [Log entries for EFS service-linked roles](logging-using-cloudtrail.md#efs-service-linked-role-ct).
For more information, see [Service-linked role permissions](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html#service-linked-role-permissions) in the *IAM User Guide*.
## Service-linked role permissions for Amazon EFS
Amazon EFS uses the service-linked role named **AWSServiceRoleForAmazonElasticFileSystem** to allow Amazon EFS to call and manage AWS resources on behalf of your EFS file systems.
The AWSServiceRoleForAmazonElasticFileSystem service-linked role trusts the `elasticfilesystem.amazonaws.com` to assume the role.
The role permissions policy allows Amazon EFS to complete the actions included in the policy definition JSON:
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"backup-storage:MountCapsule",
"ec2:CreateNetworkInterface",
"ec2:DeleteNetworkInterface",
"ec2:DescribeSecurityGroups",
"ec2:DescribeSubnets",
"ec2:DescribeNetworkInterfaceAttribute",
"ec2:ModifyNetworkInterfaceAttribute",
"tag:GetResources"
],
"Resource": "*"
},
{
"Effect": "Allow",
"Action": [
"kms:DescribeKey"
],
"Resource": "arn:aws:kms:*:*:key/*"
},
{
"Effect": "Allow",
"Action": [
"backup:CreateBackupVault",
"backup:PutBackupVaultAccessPolicy"
],
"Resource": [
"arn:aws:backup:*:*:backup-vault:aws/efs/automatic-backup-vault"
]
},
{
"Effect": "Allow",
"Action": [
"backup:CreateBackupPlan",
"backup:CreateBackupSelection"
],
"Resource": [
"arn:aws:backup:*:*:backup-plan:*"
]
},
{
"Effect": "Allow",
"Action": [
"iam:CreateServiceLinkedRole"
],
"Resource": "*",
"Condition": {
"StringEquals": {
"iam:AWSServiceName": [
"backup.amazonaws.com"
]
}
}
},
{
"Effect": "Allow",
"Action": [
"iam:PassRole"
],
"Resource": [
"arn:aws:iam::*:role/aws-service-role/backup.amazonaws.com/AWSServiceRoleForBackup"
],
"Condition": {
"StringLike": {
"iam:PassedToService": "backup.amazonaws.com"
}
}
},
{
"Effect": "Allow",
"Action": [
"elasticfilesystem:DescribeFileSystems",
"elasticfilesystem:CreateReplicationConfiguration",
"elasticfilesystem:DescribeReplicationConfigurations",
"elasticfilesystem:DeleteReplicationConfiguration",
"elasticfilesystem:ReplicationRead",
"elasticfilesystem:ReplicationWrite"
],
"Resource": "*"
}
]
}
```
------
**Note**
You must manually configure IAM permissions for AWS KMS when creating a new EFS file system that is encrypted at rest. To learn more, see [Encrypting data at rest](encryption-at-rest.md).
You must configure permissions to allow an IAM entity (such as a user, group, or role) to create, edit, or delete a service-linked role. For more information, see [ Service-linked role permissions](https://docs.aws.amazon.com/IAM/latest/UserGuide/using-service-linked-roles.html#service-linked-role-permissions) in the *IAM User Guide*.
## Creating a service-linked role for Amazon EFS
In most cases, you don't need to manually create a service-linked role. When you create mount targets or a replication configuration for your EFS file system in the AWS Management Console, the AWS CLI, or the AWS API, Amazon EFS creates the service-linked role for you.
Additionally, if you manually delete this service-linked-role, and then need to create it again, you can use the same process to recreate the role in your account. When you create mount targets or a replication configuration for your EFS file system, Amazon EFS creates the service-linked role for you.
If, however, Amazon EFS does not create the service-linked-role or if you started using Amazon EFS before it supported service-linked roles, then you can manually create the service-linked role. For instructions, see [ Creating a service-linked role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create-service-linked-role.html) in the *IAM User Guide*.
## Editing a service-linked role for Amazon EFS
Amazon EFS doesn't allow you to edit the `AWSServiceRoleForAmazonElasticFileSystem` service-linked role. After you create a service-linked role, you cannot change the name of the role because various entities might reference the role. However, you can edit the description of the role using IAM. For more information, see [Update a service-linked role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_update-service-linked-role.html) in the *IAM User Guide*.
## Deleting a service-linked role for Amazon EFS
If you no longer need to use a feature or service that requires a service-linked role, we recommend that you delete that role. That way you don't have an unused entity that is not actively monitored or maintained. However, you must clean up the resources for your service-linked role before you can manually delete it. For more information, see [Clean up resources and protect your AWS account](getting-started.md#gs-step-five-cleanup).
**Note**
If the Amazon EFS service is using the role when you try to delete the resources, then the deletion might fail. If that happens, wait for a few minutes and try the operation again.
Use the IAM console, the AWS CLI, or the AWS API to delete the AWSServiceRoleForAmazonElasticFileSystem service-linked role. For more information, see [Deleting a service-linked role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_manage_delete.html#id_roles_manage_delete_slr) in the *IAM User Guide*.
## Supported Regions for Amazon EFS service-linked roles
Amazon EFS supports using service-linked roles in all of the AWS Regions where the service is available. For more information, see [AWS service endpoints](https://docs.aws.amazon.com/general/latest/gr/rande.html) in the *AWS General Reference User Guide*.
# Troubleshooting Amazon Elastic File System identity and access
Use the following information to help you diagnose and fix common issues that you might encounter when working with Amazon EFS and IAM.
**Topics**
+ [I am not authorized to perform an action in Amazon EFS](#security_iam_troubleshoot-no-permissions)
+ [I am not authorized to perform iam:PassRole](#security_iam_troubleshoot-passrole)
+ [I want to allow people outside of my AWS account to access my Amazon EFS resources](#security_iam_troubleshoot-cross-account-access)
## I am not authorized to perform an action in Amazon EFS
If you receive an error that you're not authorized to perform an action, your policies must be updated to allow you to perform the action.
The following example error occurs when the `mateojackson` IAM user tries to use the console to view details about a fictional `my-example-widget` resource but doesn't have the fictional `elasticfilesystem:GetWidget` permissions.
```
User: arn:aws:iam::123456789012:user/mateojackson is not authorized to perform: elasticfilesystem:GetWidget on resource: my-example-widget
```
In this case, the policy for the `mateojackson` user must be updated to allow access to the `my-example-widget` resource by using the `elasticfilesystem:GetWidget` action.
If you need help, contact your AWS administrator. Your administrator is the person who provided you with your sign-in credentials.
## I am not authorized to perform iam:PassRole
If you receive an error that you're not authorized to perform the `iam:PassRole` action, your policies must be updated to allow you to pass a role to Amazon EFS.
Some AWS services allow you to pass an existing role to that service instead of creating a new service role or service-linked role. To do this, you must have permissions to pass the role to the service.
The following example error occurs when an IAM user named `marymajor` tries to use the console to perform an action in Amazon EFS. However, the action requires the service to have permissions that are granted by a service role. Mary does not have permissions to pass the role to the service.
```
User: arn:aws:iam::123456789012:user/marymajor is not authorized to perform: iam:PassRole
```
In this case, Mary's policies must be updated to allow her to perform the `iam:PassRole` action.
If you need help, contact your AWS administrator. Your administrator is the person who provided you with your sign-in credentials.
## I want to allow people outside of my AWS account to access my Amazon EFS resources
You can create a role that users in other accounts or people outside of your organization can use to access your resources. You can specify who is trusted to assume the role. For services that support resource-based policies or access control lists (ACLs), you can use those policies to grant people access to your resources.
To learn more, consult the following:
+ To learn whether Amazon EFS supports these features, see [How Amazon Elastic File System works with IAM](security_iam_service-with-iam.md).
+ To learn how to provide access to your resources across AWS accounts that you own, see [Providing access to an IAM user in another AWS account that you own](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_common-scenarios_aws-accounts.html) in the *IAM User Guide*.
+ To learn how to provide access to your resources to third-party AWS accounts, see [Providing access to AWS accounts owned by third parties](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_common-scenarios_third-party.html) in the *IAM User Guide*.
+ To learn how to provide access through identity federation, see [Providing access to externally authenticated users (identity federation)](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_common-scenarios_federated-users.html) in the *IAM User Guide*.
+ To learn the difference between using roles and resource-based policies for cross-account access, see [Cross account resource access in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies-cross-account-resource-access.html) in the *IAM User Guide*.
# Using IAM to control access to file systems
You can use both IAM identity policies and resource policies to control client access to Amazon EFS resources in a way that is scalable and optimized for cloud environments. Using IAM, you can permit clients to perform specific actions on a file system, including read-only, write, and root access. An "allow" permission on an action in *either* an IAM identity policy *or* a file system resource policy allows access for that action. The permission does not need to be granted in *both* an identity *and* a resource policy.
NFS clients can identify themselves using an IAM role when connecting to an EFS file system. When a client connects to a file system, Amazon EFS evaluates the file system’s IAM resource policy, which is called a file system policy, along with any identity-based IAM policies to determine the appropriate file system access permissions to grant.
When you use IAM authorization for NFS clients, client connections and IAM authorization decisions are logged to AWS CloudTrail. For more information about how to log Amazon EFS API calls with CloudTrail, see [Logging Amazon EFS API calls with AWS CloudTrail](logging-using-cloudtrail.md).
**Important**
You must use the EFS mount helper to mount your EFS file systems in order to use IAM authorization to control client access. For more information, see [Mounting with IAM authorization](mounting-IAM-option.md).
## Default EFS file system policy
The default EFS file system policy does not use IAM to authenticate, and grants full access to any anonymous client that can connect to the file system using a mount target. The default policy is in effect whenever a user-configured file system policy is not in effect, including at file system creation. Whenever the default file system policy is in effect, a `DescribeFileSystemPolicy` API operation returns a `PolicyNotFound` response.
## EFS actions for clients
You can specify the following actions for clients accessing a file system using a file system policy.
| Action | Description |
| --- | --- |
| `elasticfilesystem:ClientMount` | Provides read-only access to a file system. |
| `elasticfilesystem:ClientWrite` | Provides write permissions on a file system. |
| `elasticfilesystem:ClientRootAccess` | Provides use of the root user when accessing a file system. |
## EFS condition keys for clients
To express conditions, you use predefined condition keys. Amazon EFS has the following predefined condition keys for NFS clients. Any other condition keys are not enforced when using IAM controls to secure access to EFS file systems.
| EFS Condition Key | Description | Operator |
| --- | --- | --- |
| aws:SecureTransport | Use this key to require clients to use TLS when connecting to an EFS file system. | Boolean |
| aws:SourceIp | Use this key to compare the requester's IP address with the IP address that you specify in the policy. The aws:SourceIp condition key can only be used for public IP address ranges. | String |
| elasticfilesystem:AccessPointArn | ARN of the EFS access point to which the client is connecting. | String |
| elasticfilesystem:AccessedViaMountTarget | Use this key to prevent access to an EFS file system by clients that are not using file system mount targets. | Boolean |
## File system policy examples
To view examples of Amazon EFS file system policies, see [Resource-based policy examples for Amazon EFS](security_iam_resource-based-policy-examples.md).
# Compliance validation for Amazon EFS
To learn whether an AWS service is within the scope of specific compliance programs, see [AWS services in Scope by Compliance Program](https://aws.amazon.com/compliance/services-in-scope/) and choose the compliance program that you are interested in. For general information, see [AWS Compliance Programs](https://aws.amazon.com/compliance/programs/).
You can download third-party audit reports using AWS Artifact. For more information, see [Downloading Reports in AWS Artifact](https://docs.aws.amazon.com/artifact/latest/ug/downloading-documents.html).
Your compliance responsibility when using AWS services is determined by the sensitivity of your data, your company's compliance objectives, and applicable laws and regulations. For more information about your compliance responsibility when using AWS services, see [AWS Security Documentation](https://docs.aws.amazon.com/security/).
# Resilience in Amazon EFS
The AWS global infrastructure is built around AWS Regions and Availability Zones (AZs). AWS Regions provide multiple physically separated and isolated AZs, which are connected with low-latency, high-throughput, and highly redundant networking. With AZs, you can design and operate applications and databases that automatically fail over between zones without interruption. AZs are more highly available, fault tolerant, and scalable than traditional single or multiple data center infrastructures.
Amazon EFS file systems are resilient to one or more Availability Zone failures within an AWS Region. Mount targets themselves are designed to be highly available. As you design for high availability and failover to other AZs, keep in mind that while the IP addresses and DNS for your mount targets in each AZ are static, they are redundant components backed by multiple resources. For more information, see [How Amazon EFS works with Amazon EC2](how-it-works.md#how-it-works-ec2).
For more information about AWS Regions and Availability Zones, see [AWS Global Infrastructure](https://aws.amazon.com/about-aws/global-infrastructure/).
# Controlling network access to EFS file systems for NFS clients
You can control access by NFS clients to Amazon EFS file systems using network layer security and EFS file system policies. You can use the network layer security mechanisms available with Amazon EC2, such as VPC security group rules and network ACLs. You can also use AWS IAM to control NFS access with an EFS file system policy and identity-based policies.
**Topics**
+ [Using VPC security groups](network-access.md)
+ [Working with interface VPC endpoints in Amazon EFS](efs-vpc-endpoints.md)
# Using VPC security groups
When using Amazon EFS, you specify VPC security groups for your EC2 instances and security groups for the EFS mount targets associated with the file system. A security group acts as a firewall, and the rules that you add define the traffic flow. In the [Getting started exercise](getting-started.md), you created one security group when you launched the EFS instance. You then associated another with the EFS mount target (that is, the default security group for your default VPC). That approach works for the Getting started exercise. However, for a production system, you should set up security groups with minimal permissions for use with Amazon EFS.
You can authorize inbound and outbound access to your EFS file system. To do so, you add rules that allow EFS instances to connect to your EFS file system through the mount target using the Network File System (NFS) port.
+ Each EC2 instance that mounts the file system must have a security group with a rule that allows outbound access to the mount target on **NFS port 2049**.
+ The EFS mount target needs to have a security group with a rule that allows inbound access on NFS port 2049 from each EC2 instance on which you want to mount the file system.
The following table shows the specific security group rules required:
| Security Group | Rule Type | Protocol | Port | Source/Destination |
| --- | --- | --- | --- | --- |
| EC2 Instance | Outbound | TCP | 2049 | Mount target security group |
| Mount Target | Inbound | TCP | 2049 | EC2 instance security group |
## Source ports for working with Amazon EFS
To support a broad set of NFS clients, Amazon EFS allows connections from any source port. If you require that only privileged users can access Amazon EFS, we recommend using the following client firewall rule. Connect to your file system using SSH and run the following command:
```
iptables -I OUTPUT 1 -m owner --uid-owner 1-4294967294 -m tcp -p tcp --dport 2049 -j DROP
```
This command inserts a new rule at the start of the OUTPUT chain (`-I OUTPUT 1`). The rule prevents any unprivileged, nonkernel process (`-m owner --uid-owner 1-4294967294`) from opening a connection to NFS port 2049 (`-m tcp -p tcp –dport 2049`).
## Security considerations for network access
An NFS version 4.1 (NFSv4.1) client can only mount a file system if it can make a network connection to the NFS port (TCP port 2049) of one of the file system's mount targets. Similarly, an NFSv4.1 client can only assert a user and group ID when accessing a file system if it can make this network connection.
Whether you can make this network connection is governed by a combination of the following:
+ **Network isolation provided by the mount targets' VPC** – File system mount targets can't have public IP addresses associated with them. The only targets that can mount file systems are the following:
+ Amazon EC2 instances in the local Amazon VPC
+ EC2 instances in connected VPCs
+ On-premises servers connected to an Amazon VPC by using AWS Direct Connect and an AWS Virtual Private Network (VPN)
+ **Network access control lists (ACLs) for the VPC subnets of the client and mount targets, for access from outside the mount target's subnets** – To mount a file system, the client must be able to make a TCP connection to NFS port 2049 of a mount target and receive return traffic.
+ **Rules of the client's and mount targets' VPC security groups, for all access** – For an EC2 instance to mount a file system, the following security group rules must be in effect:
+ The file system must have a mount target whose network interface has a security group with a rule that enables inbound connections on NFS port 2049 from the instance. You can enable inbound connections either by IP address (CIDR range) or security group. The source of the security group rules for the inbound NFS port on mount target network interfaces is a key element of file system access control. Inbound rules other than the one for NFS port 2049, and any outbound rules, aren't used by network interfaces for file system mount targets.
+ The mounting instance must have a network interface with a security group rule that enables outbound connections to NFS port 2049 on one of the file system's mount targets. You can enable outbound connections either by IP address (CIDR range) or security group.
For more information, see [Managing mount targets](accessing-fs.md).
## Creating security groups
**To create security groups for EC2 instances and EFS mount targets**
The following are the general steps that you'll perform when creating the security groups for Amazon EFS. For instructions on creating the security groups, see [Create a security group](https://docs.aws.amazon.com/vpc/latest/userguide/creating-security-groups.html) in the *Amazon VPC User Guide*.
1. For your EC2 instances, create a security group with the following rules:
+ An inbound rule that allows inbound access using Secure Shell (SSH) on **port 22** from your IP address or network. Optionally, restrict the **Source** address for security.
+ An outbound rule that allows outbound access on NFS port 2049 to the mount target security group. Identify the mount target security group as the destination.
1. For your EFS mount target, create a security group with the following rules:
+ An inbound rule that allows access on NFS port 2049 from the EC2 security group. Identify the EC2 security group as the source.
**Note**
You don't need to add an outbound rule because the default outbound rule allows all outbound traffic.
# Working with interface VPC endpoints in Amazon EFS
To establish a private connection between your virtual private cloud (VPC) and the Amazon EFS API, you can create an interface VPC endpoint. The endpoint provides secure connectivity to the Amazon EFS API without requiring an internet gateway, NAT instance, or virtual private network (VPN) connection. For more information, see [Access an AWS service using an interface VPC endpoint](https://docs.aws.amazon.com/vpc/latest/privatelink/create-interface-endpoint.html) in the *Amazon VPC User Guide*.
Interface VPC endpoints are powered by AWS PrivateLink, a feature that enables private communication between AWS services using private IP addresses. To use AWS PrivateLink, create an interface VPC endpoint for Amazon EFS in your VPC using the Amazon VPC console, API, or CLI. Doing this creates an elastic network interface in your subnet with a private IP address that serves Amazon EFS API requests. You can also access a VPC endpoint from on-premises environments or from other VPCs using Site-to-Site VPN, Direct Connect, or VPC peering. To learn more, see [Connect your VPC to services using AWS PrivateLink](https://docs.aws.amazon.com/vpc/latest/userguide/endpoint-services-overview.html) in the *Amazon VPC User Guide*.
## Creating an interface endpoint for Amazon EFS
To create an interface VPC endpoint for Amazon EFS, use one of the following:
+ `com.amazonaws.region.elasticfilesystem` – Creates an endpoint for Amazon EFS API operations.
+ **`com.amazonaws.region.elasticfilesystem-fips`** – Creates an endpoint for the Amazon EFS API that complies with [Federal Information Processing Standard (FIPS) 140-2](https://aws.amazon.com/compliance/fips/).
For a complete list of Amazon EFS endpoints, see [Amazon Elastic File System endpoints and quotas](https://docs.aws.amazon.com/general/latest/gr/elasticfilesystem.html) in the *Amazon Web Services General Reference*.
For more information about how to create an interface endpoint, see [Access an AWS service using an interface VPC endpoint](https://docs.aws.amazon.com/vpc/latest/privatelink/create-interface-endpoint.html) in the *Amazon VPC User Guide*.
## Creating a VPC endpoint policy for Amazon EFS
To control access to the Amazon EFS API, you can attach an AWS Identity and Access Management (IAM) policy to your VPC endpoint. The policy specifies the following:
+ The principal that can perform actions.
+ The actions that can be performed.
+ The resources on which actions can be performed.
For more information, see [Control access to VPC endpoints using endpoint policies](https://docs.aws.amazon.com/vpc/latest/privatelink/vpc-endpoints-access.html) in the *Amazon VPC User Guide*.
The following example shows a VPC endpoint policy that denies everyone permission to create an EFS file system through the endpoint. The example policy also grants everyone permission to perform all other actions.
```
{
"Statement": [
{
"Action": "*",
"Effect": "Allow",
"Resource": "*",
"Principal": "*"
},
{
"Action": "elasticfilesystem:CreateFileSystem",
"Effect": "Deny",
"Resource": "*",
"Principal": "*"
}
]
}
```
# Network File System (NFS) level users, groups, and permissions
After creating a file system, by default only the root user (UID 0) has read, write, and execute permissions. For other users to modify the file system, the root user must explicitly grant them access. You can use access points to automate the creation of directories that a nonroot user can write from. For more information, see [Working with access points](efs-access-points.md).
EFS file system objects have a Unix-style mode associated with them. This mode value defines the permissions for performing actions on that object. Users familiar with Unix-style systems can easily understand how Amazon EFS behaves with respect to these permissions.
Additionally, on Unix-style systems, users and groups are mapped to numeric identifiers, which Amazon EFS uses to represent file ownership. For Amazon EFS, file system objects (that is, files, directories, and so on) are owned by a single owner and a single group. Amazon EFS uses the mapped numeric IDs to check permissions when a user attempts to access a file system object.
**Note**
The NFS protocol supports a maximum of 16 group IDs (GIDs) per user and any additional GIDs are truncated from NFS client requests. For more information, see [Access denied to allowed files on NFS file system](troubleshooting-efs-general.md#nfs-16-group-limit).
Following, you can find examples of permissions and a discussion about NFS permissions considerations for Amazon EFS.
**Topics**
+ [File and directory permissions](user-and-group-permissions.md)
+ [Example EFS file system use cases and permissions](#accessing-fs-nfs-permissions-ex-scenarios)
+ [User and group ID permissions for files and directories within a file system](#accessing-fs-nfs-permissions-uid-gid)
+ [No root squashing](#accessing-fs-nfs-permissions-root-user)
+ [Permissions caching](#accessing-fs-nfs-permissions-caching)
+ [Changing file system object ownership](#accessing-fs-nfs-permissions-chown-restricted)
+ [EFS access points](#accessing-fs-nfs-permissions-access-points)
# File and directory permissions
Files and directories in an EFS file system support standard Unix-style read, write, and execute permissions based on the user and group ID asserted by the mounting NFSv4.1 client, unless overridden by an EFS access point. For more information, see [Network File System (NFS) level users, groups, and permissions](accessing-fs-nfs-permissions.md).
**Note**
By default, this layer of access control depends on trusting the NFSv4.1 client in its assertion of the user and group ID. You can use AWS Identity and Access Management (IAM) resource-based policies and identity policies to authorize NFS clients and provide read-only, write, and root access permissions. You can use EFS access points to override the operating system user and group identity information provided by the NFS client. For more information, see [Using IAM to control access to file systems](iam-access-control-nfs-efs.md) and [Creating access points](create-access-point.md).
As an example of read, write, and execute permissions for files and directories, Alice might have permissions to read and write to any files that she wants to in her personal directory on a file system, `/alice`. However, in this example Alice is not allowed to read or write to any files in Mark's personal directory on the same file system, `/mark`. Both Alice and Mark are allowed to read but not write files in the shared directory `/share`.
## Example EFS file system use cases and permissions
After you create an EFS file system and mount targets for the file system in your VPC, you can mount the remote file system locally on your Amazon EC2 instance. The `mount` command can mount any directory in the file system. However, when you first create the file system, there is only one root directory at `/`. The root user and root group own the mounted directory.
The following `mount` command mounts the root directory of an Amazon EFS file system, identified by the file system DNS name, on the `/efs-mount-point` local directory.
```
sudo mount -t nfs -o nfsvers=4.1,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,noresvport file-system-id.efs.aws-region.amazonaws.com:/ efs-mount-point
```
The initial permissions mode allows:
+ `read-write-execute` permissions to the owner *root*
+ `read-execute` permissions to the group *root*
+ `read-execute` permissions to others
Only the root user can modify this directory. The root user can also grant other users permissions to write to this directory, for example:
+ Create writable per-user subdirectories. For step-by-step instructions, see [Tutorial: Creating writable per-user subdirectories](accessing-fs-nfs-permissions-per-user-subdirs.md).
+ Allow users to write to the EFS file system root. A user with root privileges can grant other users access to the file system.
+ To change the EFS file system ownership to a non-*root* user and group, use the following:
```
$ sudo chown user:group /EFSroot
```
+ To change permissions of the file system to something more permissive, use the following:
```
$ sudo chmod 777 /EFSroot
```
This command grants read-write-execute privileges to all users on all EC2 instances that have the file system mounted.
## User and group ID permissions for files and directories within a file system
Files and directories in an EFS file system support standard Unix-style read, write, and execute permissions based on the user ID and group IDs. When an NFS client mounts an EFS file system without using an access point, the user ID and group ID provided by the client is trusted. You can use EFS access points to override user ID and group IDs used by the NFS client. When users attempt to access files and directories, Amazon EFS checks their user IDs and group IDs to verify that each user has permission to access the objects. Amazon EFS also uses these IDs to indicate the owner and group owner for new files and directories that the user creates. Amazon EFS doesn't examine user or group names—it only uses the numeric identifiers.
**Note**
When you create a user on an EC2 instance, you can assign any numeric user ID (UID) and group ID (GID) to the user. The numeric user IDs are set in the `/etc/passwd` file on Linux systems. The numeric group IDs are in the `/etc/group` file. These files define the mappings between names and IDs. Outside of the EC2 instance, Amazon EFS doesn't perform any authentication of these IDs, including the root ID of 0.
If a user accesses an EFS file system from two different EC2 instances, depending on whether the UID for the user is the same or different on those instances you see different behavior, as follows:
+ If the user IDs are the same on both EC2 instances, Amazon EFS considers them to indicate the same user, regardless of the EC2 instance used. The user experience when accessing the file system is the same from both EC2 instances.
+ If the user IDs aren't the same on both EC2 instances, Amazon EFS considers the users to be different users. The user experience isn't the same when accessing the EFS file system from the two different EC2 instances.
+ If two different users on different EC2 instances share an ID, Amazon EFS considers them to be the same user.
You might consider managing user ID mappings across EC2 instances consistently. Users can check their numeric ID using the `id` command.
```
$ id
uid=502(joe) gid=502(joe) groups=502(joe)
```
### Turn Off the ID Mapper
The NFS utilities in the operating system include a daemon called an ID Mapper that manages mapping between user names and IDs. In Amazon Linux, the daemon is called `rpc.idmapd` and on Ubuntu is called `idmapd`. It translates user and group IDs into names, and vice versa. However, Amazon EFS deals only with numeric IDs. We recommend that you turn this process off on your EC2 instances. On Amazon Linux, the ID mapper is usually disabled, and if it is don't enable it. To turn off the ID mapper, use the commands shown following.
```
$ service rpcidmapd status
$ sudo service rpcidmapd stop
```
## No root squashing
By default, root squashing is disabled on EFS file systems. Amazon EFS behaves like a Linux NFS server with `no_root_squash`. If a user or group ID is 0, Amazon EFS treats that user as the `root` user, and bypasses permissions checks (allowing access and modification to all file system objects). Root squashing can be enabled on a client connection when the AWS Identity and Access Management (AWS IAM) identity or resource policy does not allow access to the `ClientRootAccess` action. When root squashing is enabled, the root user is converted to a user with limited permissions on the NFS server.
For more information, see [Using IAM to control access to file systems](iam-access-control-nfs-efs.md).
### Enable root squashing using IAM authorization for NFS clients
You can configure Amazon EFS to prevent root access to your EFS file system for all AWS principals except for a single management workstation. You do this by configuring AWS Identity and Access Management (IAM) authorization for Network File System (NFS) clients.
To do this requires configuring two IAM permissions policies, as follows:
+ Create an EFS file system policy that explicitly allows read and write access to the file system, and implicitly denies root access.
+ Assign an IAM identity to the Amazon EC2 management workstation that requires root access to the file system by using an EC2 instance profile. For more information about Amazon EC2 instance profiles, see [Use instance profiles](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_use_switch-role-ec2_instance-profiles.html) in the *AWS Identity and Access Management User Guide*.
+ Assign the `AmazonElasticFileSystemClientFullAccess` AWS managed policy to the IAM role of the management workstation. For more information about AWS managed policies for Amazon EFS, see [Identity and access management for Amazon EFS](security-iam.md).
To enable root squashing using IAM authorization for NFS clients, use the following procedures.
**To prevent root access to the file system**
1. Open the Amazon Elastic File System console at [https://console.aws.amazon.com/efs/](https://console.aws.amazon.com/efs/).
1. Choose **File systems**.
1. Choose the file system that you want to enable root squashing on.
1. On the file system details page, choose **File system policy**, and then choose **Edit**. The **File system policy** page appears.
1. Choose **Prevent root access by default\$1** under **Policy options**. The policy JSON object appears in the **Policy editor**.
1. Choose **Save** to save the file system policy.
Clients that aren't anonymous can get root access to the file system through an identity-based policy. When you attach the `AmazonElasticFileSystemClientFullAccess` managed policy to the workstation's role, IAM grants root access to the workstation based on its identity policy.
**To enable root access from the management workstation**
1. Open the IAM console at [https://console.aws.amazon.com/iam/](https://console.aws.amazon.com/iam/).
1. Create a role for Amazon EC2 called `EFS-client-root-access`. IAM creates an instance profile with the same name as the EC2 role you created.
1. Assign the AWS managed policy `AmazonElasticFileSystemClientFullAccess` to the EC2 role you created. The contents of this policy is shown following.
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"elasticfilesystem:ClientMount",
"elasticfilesystem:ClientRootAccess",
"elasticfilesystem:ClientWrite",
"elasticfilesystem:DescribeMountTargets"
],
"Resource": "*"
}
]
}
```
------
1. Attach the instance profile to the EC2 instance that you are using as the management workstation, as described following. For more information, see [Attaching an IAM Role to an Instance](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html#attach-iam-role) in the *Amazon EC2 User Guide for Linux Instances*.
1. Open the Amazon EC2 console at [https://console.aws.amazon.com/ec2/](https://console.aws.amazon.com/ec2/).
1. In the navigation pane, choose **Instances**.
1. Choose the instance. For **Actions**, choose **Instance Settings**, and then choose **Attach/Replace IAM role**.
1. Choose the IAM role that you created in the first step, `EFS-client-root-access`, and choose **Apply**.
1. Install the EFS mount helper on the management workstation. For more information about the EFS mount helper mount helper and the amazon-efs-utils package, see [Installing the Amazon EFS client](using-amazon-efs-utils.md).
1. Mount the EFS file system on the management workstation by using the following command with the `iam` mount option.
```
$ sudo mount -t efs -o tls,iam file-system-id:/ efs-mount-point
```
You can configure the Amazon EC2 instance to automatically mount the file system with IAM authorization. For more information about mounting an EFS file system with IAM authorization, see [Mounting with IAM authorization](mounting-IAM-option.md).
## Permissions caching
Amazon EFS caches file permissions for a small time period. As a result, there might be a brief window where a user whose access was revoked recently can still access that object.
## Changing file system object ownership
Amazon EFS enforces the POSIX `chown_restricted` attribute. This means only the root user can change the owner of a file system object. The root or the owner user can change the owner group of a file system object. However, unless the user is root, the group can only be changed to one that the owner user is a member of.
## EFS access points
An *access point *applies an operating system user, group, and file system path to any file system request made using the access point. The access point's operating system user and group override any identity information provided by the NFS client. The file system path is exposed to the client as the access point's root directory. This approach ensures that each application always uses the correct operating system identity and the correct directory when accessing shared file-based datasets. Applications using the access point can only access data in its own directory and below. For more information about access points, see [Working with access points](efs-access-points.md).
# Working with access points
EFS *access points *are application-specific entry points into an EFS file system that make it easier to manage application access to shared datasets. Access points can enforce a user identity, including the user's POSIX groups, for all file system requests that are made through the access point. Access points can also enforce a different root directory for the file system so that clients can only access data in the specified directory or its subdirectories.
You can use AWS Identity and Access Management (IAM) policies to enforce that specific applications use a specific access point. By combining IAM policies with access points, you can easily provide secure access to specific datasets for your applications.
You can create access points for an existing EFS file system using the AWS Management Console, the AWS Command Line Interface (AWS CLI), and the Amazon EFS API. For step-by-step procedures to create an access point, see [Creating access points](create-access-point.md).
## Access points work with mount targets
You must create at least one mount target in your VPC before using access points. Mount targets provide the network connectivity to your EFS file system while access points provide the access control and application-specific entry points.
Access points inherit the mount target's Availability Zone placement.
+ Security groups are applied at the mount target level, not the access point level.
+ Access points are available in all Availability Zones where you have mount targets.
+ The IAM condition key `elasticfilesystem:AccessedViaMountTarget` ensures file system access only occurs through mount targets, which applies to both direct mounts and access point mounts.
You use the EFS mount helper when mounting a file system using an access point. In the mount command, include file system ID, the access point ID, and the `tls` mount option, as shown in the following example.
```
$ mount -t efs -o tls,iam,accesspoint=fsap-abcdef0123456789a fs-abc0123def456789a: /localmountpoint
```
For more information on mounting file systems using an access point, see [Mounting with EFS access points](mounting-access-points.md).
**Topics**
+ [Access points work with mount targets](#accesspoints-and-mount-targets)
+ [Enforcing a user identity using an access point](enforce-identity-access-points.md)
+ [Enforcing a root directory with an access point](enforce-root-directory-access-point.md)
+ [Using access points in IAM policies](access-points-iam-policy.md)
# Enforcing a user identity using an access point
You can use an access point to enforce user and group information for all file system requests made through the access point. To enable this feature, you need to specify the operating system identity to enforce when you create the access point.
As part of this, you provide the following:
+ User ID – The numeric POSIX user ID for the user.
+ Group ID – The numeric POSIX group ID for the user.
+ Secondary group IDs – An optional list of secondary group IDs.
When user enforcement is enabled, Amazon EFS replaces the NFS client's user and group IDs with the identity configured on the access point for all file system operations. User enforcement also does the following:
+ The owner and group for new files and directories are set to the user ID and group ID of the access point.
+ EFS considers the user ID, group ID, and secondary group IDs of the access point when evaluating file system permissions. EFS ignores the NFS client's IDs.
**Important**
Enforcing a user identity is subject to the `ClientRootAccess` IAM permission.
For example, in some cases you might configure the access point user ID, group ID, or both to be root (that is, setting the UID, GID, or both to 0). In such cases, you must grant the `ClientRootAccess` IAM permission to the NFS client.
# Enforcing a root directory with an access point
You can use an access point to override the root directory for a file system. When you enforce a root directory, the NFS client using the access point uses the root directory configured on the access point instead of the file system's root directory.
You enable this feature by setting the access point `Path` attribute when creating an access point. The `Path` attribute is the full path of the root directory of the file system for all file system requests made through this access point. The full path can't exceed 100 characters in length. It can include up to four subdirectories.
When you specify a root directory on an access point, it becomes the root directory of the file system for the NFS client mounting the access point. For example, suppose that the root directory of your access point is `/data`. In this case, mounting `fs-12345678:/` using the access point has the same effect as mounting `fs-12345678:/data` without using the access point.
When specifying a root directory in your access point, ensure that the directory permissions are configured to allow the user of the access point to successfully mount the file system. Specifically, make sure that the execute bit is set for the access point user or group, or for everyone. For example, a directory permission value of 755 allows the directory user owner to list files, create files, and mount, and all other users to list files and mount.
## Creating the root directory for an access point
If a root directory path for an access point doesn't exist on the file system, Amazon EFS automatically creates that root directory with the ownership and permissions specified. Amazon EFS will not create the root directory if you do not specify the directory ownership and permissions at creation. This approach makes it possible to provision file system access for a specific user or application without mounting your file system from a Linux host. To create a root directory, you have to configure the root directory ownership and permission by using the following attributes when creating an access point:
+ `OwnerUid` – The numeric POSIX user ID to use as the root directory owner.
+ `OwnerGiD` – The numeric POSIX group ID to use as the root directory owner group.
+ Permissions – The Unix mode of the directory. A common configuration is 755. Ensure that the execute bit is set for the access point user so they are able to mount. This configuration gives the directory owner permission to enter, list, and write new files in the directory. It gives all other users permission to enter and list files. For more information on working with Unix file and directory modes, see [Network File System (NFS) level users, groups, and permissions](accessing-fs-nfs-permissions.md).
Amazon EFS creates an access point root directory only if the OwnUid, OwnGID, and permissions are specified for the directory. If you do not provide this information, Amazon EFS does not create the root directory. If the root directory does not exist, attempts to mount using the access point will fail.
When you mount a file system with an access point, the root directory for the access point is created if the directory doesn't already exist, provided that the root directory's OwnerUid and Permissions were specified when the access point was created. If the access point's root directory already exists before mount time, the existing permissions aren't overwritten by the access point. If you delete the root directory, EFS recreates it the next time that the file system is mounted using the access point.
**Note**
If you do not specify the ownership and permissions for an access point root directory, Amazon EFS will not create the root directory. All attempts to mount the access point will fail.
## Security model for access point root directories
When a root directory override is in effect, Amazon EFS behaves like a Linux NFS server with the `no_subtree_check` option enabled.
In the NFS protocol, servers generate file handles that are used by clients as unique references when accessing files. EFS securely generates file handles that are unpredictable and specific to an EFS file system. When a root directory override is in place, Amazon EFS doesn't disclose file handles for files outside the specified root directory. However, in some cases a user might get a file handle for a file outside of their access point by using an out-of-band mechanism. For example, they might do so if they have access to a second access point. If they do this, they can perform read and write operations on the file.
File ownership and access permissions are always enforced, for access to files within and outside of a user's access point root directory.
# Using access points in IAM policies
You can use an IAM policy to enforce that a specific NFS client, identified by its IAM role, can only access a specific access point. To do this, you use the `elasticfilesystem:AccessPointArn` IAM condition key. The `AccessPointArn` is the Amazon Resource Name (ARN) of the access point that the file system is mounted with.
Following is an example of a file system policy that allows the IAM role `app1` to access the file system using access point `fsap-01234567`. The policy also allows `app2` to use the file system using access point `fsap-89abcdef`.
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Id": "MyFileSystemPolicy",
"Statement": [
{
"Sid": "App1Access",
"Effect": "Allow",
"Principal": { "AWS": "arn:aws:iam::111122223333:role/app1" },
"Action": [
"elasticfilesystem:ClientMount",
"elasticfilesystem:ClientWrite"
],
"Resource": "arn:aws:elasticfilesystem:us-east-1:111122223333:file-system/*",
"Condition": {
"StringEquals": {
"elasticfilesystem:AccessPointArn" : "arn:aws:elasticfilesystem:us-east-1:222233334444:access-point/fsap-01234567"
}
}
},
{
"Sid": "App2Access",
"Effect": "Allow",
"Principal": { "AWS": "arn:aws:iam::111122223333:role/app2" },
"Action": [
"elasticfilesystem:ClientMount",
"elasticfilesystem:ClientWrite"
],
"Resource": "arn:aws:elasticfilesystem:us-east-1:111122223333:file-system/*",
"Condition": {
"StringEquals": {
"elasticfilesystem:AccessPointArn" : "arn:aws:elasticfilesystem:us-east-1:222233334444:access-point/fsap-89abcdef"
}
}
}
]
}
```
------
# Blocking public access to EFS file systems
The Amazon EFS block public access feature provides settings to help you manage public access to EFS file systems. By default, new EFS file systems don't allow public access. However, you can modify file system policies to allow public access.
**Important**
Enabling Block Public Access access helps protect your resources by preventing public access from being granted through the resource policies that are directly attached to the file system. In addition to enabling Block Public Access, carefully inspect the following policies to confirm that they do not grant public access:
Identity-based policies attached to associated AWS principals (for example, IAM roles)
Resource-based policies attached to associated AWS resources (for example,AWS Key Management Service (KMS) keys)
**Topics**
+ [Blocking public access with AWS Transfer Family](#block-efs-public-access-with-transferfamily)
+ [The meaning of "public"](#what-is-a-public-policy)
## Blocking public access with AWS Transfer Family
When you use Amazon EFS with AWS Transfer Family, file system access requests received from a Transfer Family server that is owned by a different account than the file system are blocked if the file system allows public access. Amazon EFS evaluates the file system's IAM policies, and if the policy is public, it blocks the request. To permit AWS Transfer Family access to your file system, update your file system policy so that it is not considered public.
**Note**
Using Transfer Family with Amazon EFS is disabled by default for AWS accounts that have EFS file systems with policies that allow public access that were created before January 6, 2021. To enable using Transfer Family to access your file system, contact AWS Support.
## The meaning of "public"
When evaluating whether a file system allows public access, Amazon EFS assumes that the file system policy is public. It then evaluates the file system policy to determine if it qualifies as non-public. To be considered non-public, a file system policy must grant access only to fixed values (values that don't contain a wild card) of one or more of the following:
+ An AWS principal, user, role, or service principal (for example, `aws:PrincipalOrgID`)
+ `aws:SourceArn`
+ `aws:SourceVpc`
+ `aws:SourceVpce`
+ `aws:SourceOwner`
+ `aws:SourceAccount`
+ `elasticfilesystem:AccessedViaMountTarget`
+ `aws:userid, outside the pattern "AROLEID:*"`
Under these rules, the following example policy is considered public.
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Id": "efs-policy-wizard-15ad9567-2546-4bbb-8168-5541b6fc0e55",
"Statement": [
{
"Sid": "efs-statement-14a7191c-9401-40e7-a388-6af6cfb7dd9c",
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": [
"elasticfilesystem:ClientMount",
"elasticfilesystem:ClientWrite",
"elasticfilesystem:ClientRootAccess"
],
"Resource": "arn:aws:elasticfilesystem:us-east-1:111122223333:file-system/*"
}
]
}
```
------
You can make this file system policy non-public by using the EFS condition key `elasticfilesystem:AccessedViaMountTarget` set to true. You can use `elasticfilesystem:AccessedViaMountTarget` to allow the specified EFS actions to clients accessing the EFS file system using a file system mount target. The following non-public policy uses the `elasticfilesystem:AccessedViaMountTarget` condition key set to true.
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Id": "efs-policy-wizard-15ad9567-2546-4bbb-8168-5541b6fc0e55",
"Statement": [
{
"Sid": "efs-statement-14a7191c-9401-40e7-a388-6af6cfb7dd9c",
"Effect": "Allow",
"Principal": {
"AWS": "*"
},
"Action": [
"elasticfilesystem:ClientMount",
"elasticfilesystem:ClientWrite",
"elasticfilesystem:ClientRootAccess"
],
"Resource": "arn:aws:elasticfilesystem:us-east-1:111122223333:file-system/*",
"Condition": {
"Bool": {
"elasticfilesystem:AccessedViaMountTarget": "true"
}
}
}
]
}
```
------
For more information about Amazon EFS condition keys, see [EFS condition keys for clients](iam-access-control-nfs-efs.md#efs-condition-keys-for-nfs). For more information about creating file system policies, see [Creating file system policies](create-file-system-policy.md).
# Network isolation for Amazon EFS
As a managed service, Amazon Elastic File System is protected by AWS global network security. For information about AWS security services and how AWS protects infrastructure, see [AWS Cloud Security](https://aws.amazon.com/security/). To design your AWS environment using the best practices for infrastructure security, see [Infrastructure Protection](https://docs.aws.amazon.com/wellarchitected/latest/security-pillar/infrastructure-protection.html) in *Security Pillar AWS Well‐Architected Framework*.
You use AWS published API calls to access Amazon EFS through the network. Clients must support the following:
+ Transport Layer Security (TLS). We require TLS 1.2 and recommend TLS 1.3.
+ Cipher suites with perfect forward secrecy (PFS) such as DHE (Ephemeral Diffie-Hellman) or ECDHE (Elliptic Curve Ephemeral Diffie-Hellman). Most modern systems such as Java 7 and later support these modes.
These APIs are callable from any network location, but Amazon EFS does support resource-based access policies which can include restrictions based on the source IP address. You can also use Amazon EFS policies to control access from specific Amazon Virtual Private Cloud (Amazon VPC) endpoints, or specific VPCs. Effectively, this isolates network access to a given Amazon EFS resource from only the specific VPC within the AWS network.