From c6b15efba5ac098c711af81c0b4e3f6e6ab07a9e Mon Sep 17 00:00:00 2001
From: m3adow <1872304+m3adow@users.noreply.github.com>
Date: Tue, 26 Nov 2024 11:33:14 +0100
Subject: [PATCH] Add rule for `container.defaultNodeServiceAccount` permission
 check

---
 ...24_003_default_node_serviceaccount_perm.py | 54 +++++++++++++++++++
 website/content/en/rules/gke/ERR/2024_003.md  | 30 +++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 gcpdiag/lint/gke/err_2024_003_default_node_serviceaccount_perm.py
 create mode 100644 website/content/en/rules/gke/ERR/2024_003.md

diff --git a/gcpdiag/lint/gke/err_2024_003_default_node_serviceaccount_perm.py b/gcpdiag/lint/gke/err_2024_003_default_node_serviceaccount_perm.py
new file mode 100644
index 000000000..1ab601d11
--- /dev/null
+++ b/gcpdiag/lint/gke/err_2024_003_default_node_serviceaccount_perm.py
@@ -0,0 +1,54 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""GKE nodes service account permissions fit container.defaultNodeServiceAccount role
+
+The service account used by GKE nodes should posess the permissions of the
+container.defaultNodeServiceAccount role, otherwise ingestion of logs or metrics
+won't work.
+"""
+
+from gcpdiag import lint, models
+from gcpdiag.queries import gke, iam
+
+ROLE = 'roles/container.defaultNodeServiceAccount'
+
+
+def prefetch_rule(context: models.Context):
+  # Make sure that we have the IAM policy in cache.
+  project_ids = {c.project_id for c in gke.get_clusters(context).values()}
+  for pid in project_ids:
+    iam.get_project_policy(pid)
+
+
+def run_rule(context: models.Context, report: lint.LintReportRuleInterface):
+  # Find all clusters with logging and metrics enabled.
+  clusters = gke.get_clusters(context)
+  iam_policy = iam.get_project_policy(context.project_id)
+  if not clusters:
+    report.add_skipped(None, 'no clusters found')
+  for _, c in sorted(clusters.items()):
+    if not c.has_logging_enabled():
+      report.add_skipped(c, 'logging disabled')
+    elif not c.has_monitoring_enabled():
+      report.add_skipped(c, 'monitoring disabled')
+    else:
+      # Verify service-account permissions for every nodepool.
+      for np in c.nodepools:
+        sa = np.service_account
+        if not iam.is_service_account_enabled(sa, context.project_id):
+          report.add_failed(np, f'service account disabled or deleted: {sa}')
+        elif not iam_policy.has_role_permissions(f'serviceAccount:{sa}', ROLE):
+          report.add_failed(np, f'service account: {sa}\nmissing role: {ROLE}')
+        else:
+          report.add_ok(np)
diff --git a/website/content/en/rules/gke/ERR/2024_003.md b/website/content/en/rules/gke/ERR/2024_003.md
new file mode 100644
index 000000000..5ac0d8819
--- /dev/null
+++ b/website/content/en/rules/gke/ERR/2024_003.md
@@ -0,0 +1,30 @@
+---
+title: "gke/ERR/2024_003"
+linkTitle: "ERR/2024_003"
+weight: 1
+type: docs
+description: >
+  GKE nodes service account permissions fit container.defaultNodeServiceAccount role :-)
+---
+
+**Product**: [Google Kubernetes Engine](https://cloud.google.com/kubernetes-engine)\
+**Rule class**: Something that is very likely to be wrong
+
+### Description
+
+The service account used by GKE nodes should posess the permissions of the container.defaultNodeServiceAccount role,
+otherwise ingestion of logs or metrics won't work.
+
+### Remediation
+
+Make sure your GKE node pool service accounts have the following role binding in the IAM policy
+
+- Principal: GKE node pool service account
+- Role: `container.defaultNodeServiceAccount`
+
+or use a custom role which
+contains [those permissions](https://cloud.google.com/iam/docs/understanding-roles#container.defaultNodeServiceAccount)
+
+### Further information
+
+- [Hardening your cluster - Use least privilege IAM service Accounts](https://cloud.google.com/linhttps://cloud.google.com/kubernetes-engine/docs/how-to/hardening-your-cluster#use_least_privilege_sa)