example-bucket-policies

Bucket Policy Examples

This section presents a few examples of typical use cases for bucket policies. The policies use bucket and examplebucket strings in the resource value. To test these policies, replace these strings with your bucket name. For information about access policy language, see Access Policy Language Overview.

Note
Bucket policies are limited to 20 KB in size.

You can use the AWS Policy Generator to create a bucket policy for your Amazon S3 bucket. You can then use the generated document to set your bucket policy by using the Amazon S3 console, through several third-party tools, or via your application.

Important
When testing permissions using the Amazon S3 console, you will need to grant additional permissions that the console requires—s3:ListAllMyBuckets, s3:GetBucketLocation, and s3:ListBucket permissions. For an example walkthrough that grants permissions to users and tests them using the console, see Walkthrough: Controlling Access to a Bucket with User Policies.

Topics

Granting Permissions to Multiple Accounts with Added Conditions

The following example policy grants the s3:PutObject and s3:PutObjectAcl permissions to multiple AWS accounts and requires that any request for these operations include the public-read canned access control list (ACL). For more information, see Specifying Permissions in a Policy and Specifying Conditions in a Policy.

1. {
2. "Version":"2012-10-17",
3. "Statement":[
4. {
5. "Sid":"AddCannedAcl",
6. "Effect":"Allow",
7. "Principal": {"AWS": ["arn:aws:iam::111122223333:root","arn:aws:iam::444455556666:root"]},
8. "Action":["s3:PutObject","s3:PutObjectAcl"],
9. "Resource":["arn:aws:s3:::examplebucket/*"],
10. "Condition":{"StringEquals":{"s3:x-amz-acl":["public-read"]}}
11. }
12. ]
13. }

Granting Read-Only Permission to an Anonymous User

The following example policy grants the s3:GetObject permission to any public anonymous users. (For a list of permissions and the operations that they allow, see Specifying Permissions in a Policy.) This permission allows anyone to read the object data, which is useful for when you configure your bucket as a website and want everyone to be able to read objects in the bucket. Before you use a bucket policy to grant read-only permission to an anonymous user, you must disable block public access settings for your bucket. For more information, see Permissions Required for Website Access.

1. {
2. "Version":"2012-10-17",
3. "Statement":[
4. {
5. "Sid":"PublicRead",
6. "Effect":"Allow",
7. "Principal": "*",
8. "Action":["s3:GetObject"],
9. "Resource":["arn:aws:s3:::examplebucket/*"]
10. }
11. ]
12. }

Warning
Use caution when granting anonymous access to your Amazon S3 bucket or disabling block public access settings. When you grant anonymous access, anyone in the world can access your bucket. We recommend that you never grant anonymous access to your Amazon S3 bucket unless you specifically need to, such as with static website hosting.

Restricting Access to Specific IP Addresses

The following example denies permissions to any user to perform any Amazon S3 operations on objects in the specified S3 bucket. However, the request must not originate from the range of IP addresses specified in the condition.

The condition in this statement identifies the 54.240.143.* as the range of allowed Internet Protocol version 4 (IPv4) IP addresses.

The Condition block uses the NotIpAddress condition and the aws:SourceIp condition key, which is an AWS-wide condition key. For more information about these condition keys, see Specifying Conditions in a Policy. The aws:SourceIp IPv4 values use the standard CIDR notation. For more information, see IAM JSON Policy Elements Reference in the IAM User Guide.

1. {
2. "Version": "2012-10-17",
3. "Id": "S3PolicyId1",
4.
5. "Statement": [
6.
7. {
8. "Sid": "IPAllow",
9. "Effect": "Deny",
10. "Principal": "*",
11. "Action": "s3:*",
12. "Resource": "arn:aws:s3:::examplebucket/*",
13. "Condition": {
14. "NotIpAddress": {"aws:SourceIp": "54.240.143.0/24"}
15.
16. }
17. }
18. ]
19. }

Allowing IPv4 and IPv6 Addresses

When you start using IPv6 addresses, we recommend that you update all of your organization's policies with your IPv6 address ranges in addition to your existing IPv4 ranges to ensure that the policies continue to work as you make the transition to IPv6.

The following example bucket policy shows how to mix IPv4 and IPv6 address ranges to cover all of your organization's valid IP addresses. The example policy would allow access to the example IP addresses 54.240.143.1 and 2001:DB8:1234:5678::1 and would deny access to the addresses 54.240.143.129 and 2001:DB8:1234:5678:ABCD::1.

The IPv6 values for aws:SourceIp must be in standard CIDR format. For IPv6, we support using :: to represent a range of 0s (for example, 2032001:DB8:1234:5678::/64). For more information, see IP Address Condition Operators in the IAM User Guide.

1. {
2. "Id":"PolicyId2",
3. "Version":"2012-10-17",
4. "Statement":[
5. {
6. "Sid":"AllowIPmix",
7. "Effect":"Allow",
8. "Principal":"*",
9. "Action":"s3:*",
10. "Resource":"arn:aws:s3:::examplebucket/*",
11. "Condition": {
12. "IpAddress": {
13. "aws:SourceIp": [
14. "54.240.143.0/24",
15. "2001:DB8:1234:5678::/64"
16. ]
17. },
18. "NotIpAddress": {
19. "aws:SourceIp": [
20. "54.240.143.128/30",
21. "2001:DB8:1234:5678:ABCD::/80"
22. ]
23. }
24. }
25. }
26. ]
27. }

Restricting Access to a Specific HTTP Referer

Suppose that you have a website with a domain name (www.example.com or example.com) with links to photos and videos stored in your Amazon S3 bucket, examplebucket. By default, all the Amazon S3 resources are private, so only the AWS account that created the resources can access them. To allow read access to these objects from your website, you can add a bucket policy that allows s3:GetObject permission with a condition, using the aws:Referer key, that the get request must originate from specific webpages. The following policy specifies the StringLike condition with the aws:Referer condition key.

1. {
2. "Version":"2012-10-17",
3. "Id":"http referer policy example",
4. "Statement":[
5. {
6. "Sid":"Allow get requests originating from www.example.com and example.com.",
7. "Effect":"Allow",
8. "Principal":"*",
9. "Action":"s3:GetObject",
10. "Resource":"arn:aws:s3:::examplebucket/*",
11. "Condition":{
12. "StringLike":{"aws:Referer":["http://www.example.com/*","http://example.com/*"]}
13. }
14. }
15. ]
16. }

Make sure the browsers you use include the HTTP referer header in the request.

You can further secure access to objects in the examplebucket bucket by adding explicit deny to the bucket policy as shown in the following example. Explicit deny supersedes any permission you might grant to objects in the examplebucket bucket using other means such as ACLs or user policies.

Important
This example prevents all users (including the root user) from performing all Amazon S3 actions, including managing bucket policies. Consider adding a third Sid that grants the root user s3:* actions.

1. {
2. "Version": "2012-10-17",
3. "Id": "http referer policy example",
4. "Statement": [
5. {
6. "Sid": "Allow get requests referred by www.example.com and example.com.",
7. "Effect": "Allow",
8. "Principal": "*",
9. "Action": "s3:GetObject",
10. "Resource": "arn:aws:s3:::examplebucket/*",
11. "Condition": {
12. "StringLike": {"aws:Referer": ["http://www.example.com/*","http://example.com/*"]}
13. }
14. },
15. {
16. "Sid": "Explicit deny to ensure requests are allowed only from specific referer.",
17. "Effect": "Deny",
18. "Principal": "*",
19. "Action": "s3:*",
20. "Resource": "arn:aws:s3:::examplebucket/*",
21. "Condition": {
22. "StringNotLike": {"aws:Referer": ["http://www.example.com/*","http://example.com/*"]}
23. }
24. }
25. ]
26. }

Granting Permission to an Amazon CloudFront Origin Identity

The following example bucket policy grants a CloudFront Origin Identity permission to get (list) all objects in your Amazon S3 bucket. The CloudFront Origin Identity is used to enable the CloudFront private content feature. The policy uses the CanonicalUser prefix, instead of AWS, to specify a Canonical User ID. To learn more about CloudFront support for serving private content, see Serving Private Content with Signed URLs and Signed Cookies in the Amazon CloudFront Developer Guide. You must specify the canonical user ID for your CloudFront distribution's origin access identity. For instructions about finding the canonical user ID, see Specifying a Principal in a Policy.

1. {
2. "Version":"2012-10-17",
3. "Id":"PolicyForCloudFrontPrivateContent",
4. "Statement":[
5. {
6. "Sid":" Grant a CloudFront Origin Identity access to support private content",
7. "Effect":"Allow",
8. "Principal":{ "AWS":"arn:aws:iam::cloudfront:user/CloudFront Origin Access Identity ID"},
9. "Action":"s3:GetObject",
10. "Resource":"arn:aws:s3:::examplebucket/*"
11. }
12. ]
13. }

Adding a Bucket Policy to Require MFA

Amazon S3 supports MFA-protected API access, a feature that can enforce multi-factor authentication (MFA) for access to your Amazon S3 resources. Multi-factor authentication provides an extra level of security that you can apply to your AWS environment. It is a security feature that requires users to prove physical possession of an MFA device by providing a valid MFA code. For more information, see AWS Multi-Factor Authentication. You can require MFA for any requests to access your Amazon S3 resources.

You can enforce the MFA requirement using the aws:MultiFactorAuthAge key in a bucket policy. AWS Identity and Access Management (IAM) users can access Amazon S3 resources by using temporary credentials issued by the AWS Security Token Service (AWS STS). You provide the MFA code at the time of the AWS STS request.

When Amazon S3 receives a request with multi-factor authentication, the aws:MultiFactorAuthAge key provides a numeric value indicating how long ago (in seconds) the temporary credential was created. If the temporary credential provided in the request was not created using an MFA device, this key value is null (absent). In a bucket policy, you can add a condition to check this value, as shown in the following example bucket policy. The policy denies any Amazon S3 operation on the /taxdocuments folder in the examplebucket bucket if the request is not authenticated using MFA. To learn more about MFA, see Using Multi-Factor Authentication (MFA) in AWS in the IAM User Guide.

1. {
2. "Version": "2012-10-17",
3. "Id": "123",
4. "Statement": [
5. {
6. "Sid": "",
7. "Effect": "Deny",
8. "Principal": "*",
9. "Action": "s3:*",
10. "Resource": "arn:aws:s3:::examplebucket/taxdocuments/*",
11. "Condition": { "Null": { "aws:MultiFactorAuthAge": true }}
12. }
13. ]
14. }

The Null condition in the Condition block evaluates to true if the aws:MultiFactorAuthAge key value is null, indicating that the temporary security credentials in the request were created without the MFA key.

The following bucket policy is an extension of the preceding bucket policy. It includes two policy statements. One statement allows the s3:GetObject permission on a bucket (examplebucket) to everyone. Another statement further restricts access to the examplebucket/taxdocuments folder in the bucket by requiring MFA.

1. {
2. "Version": "2012-10-17",
3. "Id": "123",
4. "Statement": [
5. {
6. "Sid": "",
7. "Effect": "Deny",
8. "Principal": "*",
9. "Action": "s3:*",
10. "Resource": "arn:aws:s3:::examplebucket/taxdocuments/*",
11. "Condition": { "Null": { "aws:MultiFactorAuthAge": true } }
12. },
13. {
14. "Sid": "",
15. "Effect": "Allow",
16. "Principal": "*",
17. "Action": ["s3:GetObject"],
18. "Resource": "arn:aws:s3:::examplebucket/*"
19. }
20. ]
21. }

You can optionally use a numeric condition to limit the duration for which the aws:MultiFactorAuthAge key is valid, independent of the lifetime of the temporary security credential used in authenticating the request. For example, the following bucket policy, in addition to requiring MFA authentication, also checks how long ago the temporary session was created. The policy denies any operation if the aws:MultiFactorAuthAge key value indicates that the temporary session was created more than an hour ago (3,600 seconds).

1. {
2. "Version": "2012-10-17",
3. "Id": "123",
4. "Statement": [
5. {
6. "Sid": "",
7. "Effect": "Deny",
8. "Principal": "*",
9. "Action": "s3:*",
10. "Resource": "arn:aws:s3:::examplebucket/taxdocuments/*",
11. "Condition": {"Null": {"aws:MultiFactorAuthAge": true }}
12. },
13. {
14. "Sid": "",
15. "Effect": "Deny",
16. "Principal": "*",
17. "Action": "s3:*",
18. "Resource": "arn:aws:s3:::examplebucket/taxdocuments/*",
19. "Condition": {"NumericGreaterThan": {"aws:MultiFactorAuthAge": 3600 }}
20. },
21. {
22. "Sid": "",
23. "Effect": "Allow",
24. "Principal": "*",
25. "Action": ["s3:GetObject"],
26. "Resource": "arn:aws:s3:::examplebucket/*"
27. }
28. ]
29. }

Granting Cross-Account Permissions to Upload Objects While Ensuring the Bucket Owner Has Full Control

You can allow another AWS account to upload objects to your bucket. However, you might decide that as a bucket owner you must have full control of the objects uploaded to your bucket. The following policy enforces that a specific AWS account (111111111111) be denied the ability to upload objects unless that account grants full-control access to the bucket owner identified by the email address (xyz@amazon.com). The StringNotEquals condition in the policy specifies the s3:x-amz-grant-full-control condition key to express the requirement (see Specifying Conditions in a Policy).

1. {
2. "Version":"2012-10-17",
3. "Statement":[
4. {
5. "Sid":"111",
6. "Effect":"Allow",
7. "Principal":{"AWS":"1111111111"},
8. "Action":"s3:PutObject",
9. "Resource":"arn:aws:s3:::examplebucket/*"
10. },
11. {
12. "Sid":"112",
13. "Effect":"Deny",
14. "Principal":{"AWS":"1111111111" },
15. "Action":"s3:PutObject",
16. "Resource":"arn:aws:s3:::examplebucket/*",
17. "Condition": {
18. "StringNotEquals": {"s3:x-amz-grant-full-control":["emailAddress=xyz@amazon.com"]}
19. }
20. }
21. ]
22. }

Granting Permissions for Amazon S3 Inventory and Amazon S3 Analytics

Amazon S3 inventory creates lists of the objects in an Amazon S3 bucket, and Amazon S3 analytics export creates output files of the data used in the analysis. The bucket that the inventory lists the objects for is called the source bucket. The bucket where the inventory file is written and the bucket where the analytics export file is written is called a destination bucket. You must create a bucket policy for the destination bucket when setting up inventory for an Amazon S3 bucket and when setting up the analytics export. For more information, see Amazon S3 Inventory and Amazon S3 Analytics – Storage Class Analysis.

The following example bucket policy grants Amazon S3 permission to write objects (PUTs) from the account for the source bucket to the destination bucket. You use a bucket policy like this on the destination bucket when setting up Amazon S3 inventory and Amazon S3 analytics export.

1. {
2. "Version":"2012-10-17",
3. "Statement":[
4. {
5. "Sid":"InventoryAndAnalyticsExamplePolicy",
6. "Effect":"Allow",
7. "Principal": {"Service": "s3.amazonaws.com"},
8. "Action":["s3:PutObject"],
9. "Resource":["arn:aws:s3:::destination-bucket/*"],
10. "Condition": {
11. "ArnLike": {
12. "aws:SourceArn": "arn:aws:s3:::source-bucket"
13. },
14. "StringEquals": {
15. "aws:SourceAccount": "1234567890",
16. "s3:x-amz-acl": "bucket-owner-full-control"
17. }
18. }
19. }
20. ]
21. }
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