Add Session tags and external id support for AWS Secrets #18813

harsimranmaan · 2023-01-24T01:06:52Z

It is now possible to set the AWS session tags and external id when assuming an IAM role via STS AssumeRole.

Here's an example setup

AWS Role - Trust relationship needs the sts:TagSession permission set as described in https://docs.aws.amazon.com/IAM/latest/UserGuide/id_session-tags.html#id_session-tags_permissions-required

vault secrets enable aws
vault write aws/config/root access_key=<key> secret_key=<secret> region=us-west-2
vault write aws/roles/my-role credential_type=assumed_role max_sts_ttl=1h role_arns="arn:aws:iam::000000000000:role/test" session_tags="department=eng" session_tags="project=p1" external_id=123

Read the role definition

vault read  aws/roles/my-role
Key                         Value
---                         -----
credential_type             assumed_role
default_sts_ttl             0s
external_id                 123
iam_groups                  <nil>
iam_tags                    <nil>
max_sts_ttl                 1h
permissions_boundary_arn    n/a
policy_arns                 <nil>
policy_document             n/a
role_arns                   [arn:aws:iam::000000000000:role/test]
session_tags                map[department:eng project:p1]
user_path                   n/a

vault read  aws/sts/my-role
Key               Value
---               -----
access_key        XXXX
arn               arn:aws:sts::000000000000:assumed-role/test/vault-token-my-role-1674516375-mBKZQssrwtP6gl3kbmWq
secret_key        XXX
security_token    XXX
ttl               59m59s

The cloudtrail for AssumeRole looks like

	"userIdentity": {
        "type": "IAMUser",
        "principalId": "XXX",
        "arn": "arn:aws:iam::000000000000:user/vault-user",
        "accountId": "000000000000",
        "accessKeyId": "XXX",
        "userName": "vault-user"
    },
    "eventTime": "2023-01-23T23:31:12Z",
    "eventSource": "sts.amazonaws.com",
    "eventName": "AssumeRole",
    "awsRegion": "us-east-1",
    "sourceIPAddress": "XXX",
    "userAgent": "aws-sdk-go/1.44.128 (go1.19.5; darwin; arm64)",
    "requestParameters": {
        "roleArn": "arn:aws:iam::000000000000:role/test",
        "roleSessionName": "vault-token-my-role-1674516375",
        "durationSeconds": 3600,
        "tags": [
            {
                "key": "department",
                "value": "eng"
            },
            {
                "key": "project",
                "value": "p1"
            }
        ],
        "externalId": "123"
    },
	...

When using the creds are used for accessing an S3 resource with Attribute-based Access Control (ABAC), you can now see that only requests with principalTag project=p1 are allowed while requests to path p2 are denied.

aws s3 cp a.txt s3://session-tags-test/p1/a.txt
upload: ./a.txt to s3://session-tags-test/p1/a.txt
➜  ~ aws s3 cp a.txt s3://session-tags-test/p2/a.txt
upload failed: ./a.txt to s3://session-tags-test/p2/a.txt An error occurred (AccessDenied) when calling the PutObject operation: Access Denied

The IAM policy had the following block in the above case

	{
            "Action": [
                "s3:Describe*",
                "s3:Get*",
                "s3:List*",
                "s3:PutObject*"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:s3:::session-tags-test/${aws:PrincipalTag/project}/*",
                "arn:aws:s3:::session-tags-test/${aws:PrincipalTag/project}"
            ]
        }

Troubleshooting:
Error:

 Error assuming role: AccessDenied: User: arn:aws:iam::000000000000:user/vault-user is not authorized to perform: sts:TagSession on resource: arn:aws:iam::000000000000:role/test
	status code: 403, request id: ba8ab60e-2fdf-4668-81ad-5fe83e9b898e

Remedy: Assign the sts:TagSession permission to the arn:aws:iam::000000000000:role/test. See https://docs.aws.amazon.com/IAM/latest/UserGuide/id_session-tags.html#id_session-tags_permissions-required

Error:

* Error assuming role: AccessDenied: User: arn:aws:iam::000000000000:user/vault-user is not authorized to perform: sts:AssumeRole on resource: arn:aws:iam::000000000000:role/test
	status code: 403, request id: c0117588-9c84-490d-9b36-91135545dec1

Remedy: If the external ID is set, follow https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-user_externalid.html to ensure that external ID matches the ID set on the role. If you have not added the externalID condition on the role, it would not affect the assume role operation when an external ID is set only in Vault.

This change does not add support for transitive keys but it should be simple to add it in the future.

Closes #3790 #7960

harsimranmaan · 2023-01-31T00:52:34Z

Hi @hsimon-hashicorp, any chance this could be reviewed by the team? Would like this to make the cut for 1.13

snakebyte91 · 2023-07-20T12:04:44Z

Would be very good if you could pass the external id to the aws/sts endpoint:

vault write aws/sts/my-role ttl=10m external-id=<external-id>

So even a Vault admin could not assume the IAM role without the external id.

harsimranmaan · 2023-08-03T04:40:42Z

Would be very good if you could pass the external id to the aws/sts endpoint:
vault write aws/sts/my-role ttl=10m external-id=<external-id>
So even a Vault admin could not assume the IAM role without the external id.

That could be done as an extension to this but if you are a Vault admin, you can always decide to non-hmac the request keys and see what ext-id is being used.

It is now possible to set the AWS session tags and external id when assuming an IAM role via STS AssumeRole. Here's an example setup AWS Role - Trust relationship needs the `sts:TagSession` permission set as described in https://docs.aws.amazon.com/IAM/latest/UserGuide/id_session-tags.html#id_session-tags_permissions-required ```bash vault secrets enable aws vault write aws/config/root access_key=<key> secret_key=<secret> region=us-west-2 vault write aws/roles/my-role credential_type=assumed_role max_sts_ttl=1h role_arns="arn:aws:iam::000000000000:role/test" session_tags="department=eng" session_tags="project=p1" external_id=123 ``` Read the role definition ``` vault read aws/roles/my-role Key Value --- ----- credential_type assumed_role default_sts_ttl 0s external_id 123 iam_groups <nil> iam_tags <nil> max_sts_ttl 1h permissions_boundary_arn n/a policy_arns <nil> policy_document n/a role_arns [arn:aws:iam::000000000000:role/test] session_tags map[department:eng project:p1] user_path n/a ``` ```bash vault read aws/sts/my-role Key Value --- ----- access_key XXXX arn arn:aws:sts::000000000000:assumed-role/test/vault-token-my-role-1674516375-mBKZQssrwtP6gl3kbmWq secret_key XXX security_token XXX ttl 59m59s ``` The cloudtrail for AssumeRole looks like ``` "userIdentity": { "type": "IAMUser", "principalId": "XXX", "arn": "arn:aws:iam::000000000000:user/vault-user", "accountId": "000000000000", "accessKeyId": "XXX", "userName": "vault-user" }, "eventTime": "2023-01-23T23:31:12Z", "eventSource": "sts.amazonaws.com", "eventName": "AssumeRole", "awsRegion": "us-east-1", "sourceIPAddress": "XXX", "userAgent": "aws-sdk-go/1.44.128 (go1.19.5; darwin; arm64)", "requestParameters": { "roleArn": "arn:aws:iam::000000000000:role/test", "roleSessionName": "vault-token-my-role-1674516375", "durationSeconds": 3600, "tags": [ { "key": "department", "value": "eng" }, { "key": "project", "value": "p1" } ], "externalId": "123" }, ... ``` When using the creds are used for accessing an S3 resource with Attribute-based Access Control (ABAC), you can now see that only requests with principalTag project=p1 are allowed while requests to path p2 are denied. ``` aws s3 cp a.txt s3://session-tags-test/p1/a.txt upload: ./a.txt to s3://session-tags-test/p1/a.txt ➜ ~ aws s3 cp a.txt s3://session-tags-test/p2/a.txt upload failed: ./a.txt to s3://session-tags-test/p2/a.txt An error occurred (AccessDenied) when calling the PutObject operation: Access Denied ``` The IAM policy had the following block in the above case ``` { "Action": [ "s3:Describe*", "s3:Get*", "s3:List*", "s3:PutObject*" ], "Effect": "Allow", "Resource": [ "arn:aws:s3:::session-tags-test/${aws:PrincipalTag/project}/*", "arn:aws:s3:::session-tags-test/${aws:PrincipalTag/project}" ] } ``` Troubleshooting: Error: ``` Error assuming role: AccessDenied: User: arn:aws:iam::000000000000:user/vault-user is not authorized to perform: sts:TagSession on resource: arn:aws:iam::000000000000:role/test status code: 403, request id: ba8ab60e-2fdf-4668-81ad-5fe83e9b898e ``` Remedy: Assign the `sts:TagSession` permission to the `arn:aws:iam::000000000000:role/test`. See https://docs.aws.amazon.com/IAM/latest/UserGuide/id_session-tags.html#id_session-tags_permissions-required Error: ``` * Error assuming role: AccessDenied: User: arn:aws:iam::000000000000:user/vault-user is not authorized to perform: sts:AssumeRole on resource: arn:aws:iam::000000000000:role/test status code: 403, request id: c0117588-9c84-490d-9b36-91135545dec1 ``` Remedy: If the external ID is set, follow https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-user_externalid.html to ensure that external ID matches the ID set on the role. If you have not added the externalID condition on the role, it would not affect the assume role operation when an external ID is set only in Vault. This change does not add support for transitive keys but it should be simple to add it in the future. Closes hashicorp#3790 hashicorp#7960

harsimranmaan · 2023-08-03T04:55:39Z

rebased and resolved merge conflicts.

catrielg · 2024-03-06T15:36:59Z

This feature is super useful and needed. Is there any ETA on when it will be available and documented?

catrielg · 2024-05-05T10:55:39Z

bump @hsimon-hashicorp + @harsimranmaan - any chance this can be implemented soon?

edenzv · 2024-06-19T13:46:26Z

I'm join to @catrielg that this feature is needed. @hsimon-hashicorp any chance this can be implemented soon?

asvinours · 2024-06-19T15:51:23Z

This was released in 1.17.0, I think it covers part of this request?

Add ExternalID support to AWS Auth STS configuration Add ExternalID support to AWS Auth STS configuration #26628

leirtac12 · 2024-06-20T07:02:50Z

@asvinours You're correct, this does indeed cover part of this request. Unfortunately the feature that is most useful to me is the session tags part as we rely on them for ABAC.

robmonte · 2024-06-21T21:26:24Z

Hi @harsimranmaan
Thank you for the contribution!

Would you be interested in updating this PR once again to account for recent changes causing merge conflicts? My initial look seems good but I'd like to give it a more thorough test after the conflicts get resolved.

Prefer to let the AWS API enforce its own constraints. If the max number of tags is exceeded AWS will return an error. In addition, the check was never being enforced since it as conditional on an invalid config error.

robmonte

Looks good to me! Seems like builtin/logical/aws/backend_test.go needs to be updated but only to account for the two new fields in the expected output then it's good to go!

benashz · 2024-06-26T21:08:18Z

Hi @harsimranmaan,

Since adding this feature requires more extensive testing, we are going to be taking over the work needed to land it. Thanks again for your contribution to HashiCorp!

-ben

harsimranmaan requested a review from a team January 24, 2023 01:06

heatherezell added ecosystem secret/aws labels Jan 24, 2023

harsimranmaan force-pushed the session_tags branch from 57e0fe2 to 5f48fde Compare January 24, 2023 01:24

harsimranmaan mentioned this pull request Mar 1, 2023

AWS Secrets Engine templated session tags #19412

Open

fairclothjm mentioned this pull request Aug 1, 2023

Add support for AWS STS external ID #5033

Closed

harsimranmaan force-pushed the session_tags branch from 5f48fde to 8470de9 Compare August 3, 2023 04:55

benashz added 2 commits June 26, 2024 09:51

Merge branch 'main' into session_tags

03583e9

Remove max tags check

90769d2

Prefer to let the AWS API enforce its own constraints. If the max number of tags is exceeded AWS will return an error. In addition, the check was never being enforced since it as conditional on an invalid config error.

benashz requested a review from a team as a code owner June 26, 2024 13:58

benashz added 2 commits June 26, 2024 10:01

Fix external_id description

a39aa8a

Add validation tests

6dfb22a

benashz modified the milestone: 1.17.1 Jun 26, 2024

Add changelog

017d562

benashz force-pushed the session_tags branch from d39164b to 017d562 Compare June 26, 2024 16:46

robmonte approved these changes Jun 26, 2024

View reviewed changes

Update API docs

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benashz requested a review from a team as a code owner June 26, 2024 17:19

benashz self-requested a review June 26, 2024 17:20

benashz closed this Jun 26, 2024

benashz mentioned this pull request Jun 26, 2024

AWS secrets: add support for STS session tags #27620

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hc-github-team-secure-vault-core mentioned this pull request Jul 2, 2024

Backport of AWS secrets: add support for STS session tags into release/1.17.x #27662

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Add Session tags and external id support for AWS Secrets #18813

Add Session tags and external id support for AWS Secrets #18813

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Add Session tags and external id support for AWS Secrets #18813

Add Session tags and external id support for AWS Secrets #18813

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