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113 lines
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113 lines
4.3 KiB
Plaintext
---
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layout: docs
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page_title: AliCloud - Auth Methods
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description: The AliCloud auth method allows automated authentication of AliCloud entities.
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---
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# AliCloud Auth Method
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The `alicloud` auth method provides an automated mechanism to retrieve
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a Vault token for AliCloud entities. Unlike most Vault auth methods, this
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method does not require manual first-deploying, or provisioning
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security-sensitive credentials (tokens, username/password, client certificates,
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etc), by operators. It treats AliCloud as a Trusted Third Party and uses a
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special AliCloud request signed with private credentials. A variety of credentials
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can be used to construct the request, but AliCloud offers
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[instance metadata](https://www.alibabacloud.com/help/faq-detail/49122.htm)
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that's ideally suited for the purpose. By launching an instance with a role,
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the role's STS credentials under instance metadata can be used to securely
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build the request.
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## Authentication Workflow
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The AliCloud STS API includes a method,
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[`sts:GetCallerIdentity`](https://www.alibabacloud.com/help/doc-detail/43767.htm),
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which allows you to validate the identity of a client. The client signs
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a `GetCallerIdentity` query using the [AliCloud signature
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algorithm](https://www.alibabacloud.com/help/doc-detail/67332.htm). It then
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submits 2 pieces of information to the Vault server to recreate a valid signed
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request: the request URL, and the request headers. The Vault server then
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reconstructs the query and forwards it on to the AliCloud STS service and validates
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the result back.
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Importantly, the credentials used to sign the GetCallerIdentity request can come
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from the ECS instance metadata service for an ECS instance, which obviates the
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need for an operator to manually provision some sort of identity material first.
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However, the credentials can, in principle, come from anywhere, not just from
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the locations AliCloud has provided for you.
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Each signed AliCloud request includes the current timestamp and a nonce to mitigate
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the risk of replay attacks.
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It's also important to note that AliCloud does NOT include any sort
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of authorization around calls to `GetCallerIdentity`. For example, if you have
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a RAM policy on your credential that requires all access to be MFA authenticated,
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non-MFA authenticated credentials will still be able to authenticate to Vault
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using this method. It does not appear possible to enforce a RAM principal to be
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MFA authenticated while authenticating to Vault.
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## Authorization Workflow
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The basic mechanism of operation is per-role.
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Roles are associated with a role ARN that has been pre-created in AliCloud.
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AliCloud's console displays each role's ARN. A role in Vault has a 1:1 relationship
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with a role in AliCloud, and must bear the same name.
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When a client assumes that role and sends its `GetCallerIdentity` request to Vault,
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Vault matches the arn of its assumed role with that of a pre-created role in Vault.
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It then checks what policies have been associated with the role, and grants a
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token accordingly.
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## Authentication
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### Via the CLI
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#### Enable AliCloud authentication in Vault.
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```shell-session
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$ vault auth enable alicloud
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```
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#### Configure the policies on the role.
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```shell-session
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$ vault write auth/alicloud/role/dev-role arn='acs:ram::5138828231865461:role/dev-role'
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```
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#### Perform the login operation
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```shell-session
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$ vault write auth/alicloud/login \
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role=dev-role \
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identity_request_url=$IDENTITY_REQUEST_URL_BASE_64 \
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identity_request_headers=$IDENTITY_REQUEST_HEADERS_BASE_64
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```
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For the RAM auth method, generating the signed request is a non-standard
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operation. The Vault CLI supports generating this for you:
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```shell-session
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$ vault login -method=alicloud access_key=... secret_key=... security_token=... region=...
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```
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This assumes you have the AliCloud credentials you would find on an ECS instance using the
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following call:
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```
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curl 'http://100.100.100.200/latest/meta-data/ram/security-credentials/$ROLE_NAME'
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```
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Please note the `$ROLE_NAME` above is case-sensitive and must be consistent with how it's reflected
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on the instance.
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An example of how to generate the required request values for the `login` method
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can be found found in the
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[Vault CLI source code](https://github.com/hashicorp/vault-plugin-auth-alicloud/blob/master/tools/tools.go).
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## API
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The AliCloud auth method has a full HTTP API. Please see the
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[AliCloud Auth API](/api/auth/alicloud) for more
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details.
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