feat: add Kubernetes multiplayer security baseline

deploy/k8s/base/control-plane-deployment.yaml

@@ -0,0 +1,59 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: control-plane
+  labels:
+    app.kubernetes.io/name: control-plane
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: control-plane
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: control-plane
+    spec:
+      serviceAccountName: control-plane
+      automountServiceAccountToken: false
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 10001
+        runAsGroup: 10001
+        seccompProfile:
+          type: RuntimeDefault
+      containers:
+        - name: control-plane
+          image: ghcr.io/cosmic-clash/control-plane@sha256:0000000000000000000000000000000000000000000000000000000000000000
+          ports:
+            - name: http
+              containerPort: 8080
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop: [ALL]
+          resources:
+            requests:
+              cpu: 100m
+              memory: 128Mi
+            limits:
+              cpu: 1
+              memory: 512Mi
+          env:
+            - name: DATABASE_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: cosmic-clash-database
+                  key: password
+            - name: REDIS_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: cosmic-clash-redis
+                  key: password
+            - name: STEAM_PUBLISHER_KEY
+              valueFrom:
+                secretKeyRef:
+                  name: cosmic-clash-steam
+                  key: publisher-key
+

deploy/k8s/base/kustomization.yaml

@@ -0,0 +1,10 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+namespace: cosmic-clash
+resources:
+  - namespace.yaml
+  - service-accounts.yaml
+  - rbac.yaml
+  - network-policies.yaml
+  - control-plane-deployment.yaml
+

deploy/k8s/base/namespace.yaml

@@ -0,0 +1,9 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: cosmic-clash
+  labels:
+    pod-security.kubernetes.io/enforce: restricted
+    pod-security.kubernetes.io/audit: restricted
+    pod-security.kubernetes.io/warn: restricted
+

deploy/k8s/base/network-policies.yaml

@@ -0,0 +1,67 @@
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: default-deny-ingress-egress
+spec:
+  podSelector: {}
+  policyTypes: [Ingress, Egress]
+---
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: control-plane-allowed-flows
+spec:
+  podSelector:
+    matchLabels:
+      app.kubernetes.io/name: control-plane
+  policyTypes: [Ingress, Egress]
+  ingress:
+    - from:
+        - namespaceSelector: {}
+          podSelector:
+            matchLabels:
+              app.kubernetes.io/name: edge-gateway
+      ports:
+        - protocol: TCP
+          port: 8080
+  egress:
+    - to:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: data
+          podSelector:
+            matchLabels:
+              app.kubernetes.io/name: postgres
+      ports:
+        - protocol: TCP
+          port: 5432
+    - to:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: data
+          podSelector:
+            matchLabels:
+              app.kubernetes.io/name: redis
+      ports:
+        - protocol: TCP
+          port: 6379
+    - to:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: agones-system
+      ports:
+        - protocol: TCP
+          port: 443
+    - ports:
+        - protocol: UDP
+          port: 53
+        - protocol: TCP
+          port: 53
+      to:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: kube-system
+          podSelector:
+            matchLabels:
+              k8s-app: kube-dns
+

deploy/k8s/base/rbac.yaml

@@ -0,0 +1,24 @@
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: control-plane-agones-allocator
+  namespace: agones-system
+rules:
+  - apiGroups: ["allocation.agones.dev"]
+    resources: ["gameserverallocations"]
+    verbs: ["create"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: cosmic-clash-control-plane-agones-allocator
+  namespace: agones-system
+subjects:
+  - kind: ServiceAccount
+    name: control-plane
+    namespace: cosmic-clash
+roleRef:
+  kind: Role
+  name: control-plane-agones-allocator
+  apiGroup: rbac.authorization.k8s.io
+

deploy/k8s/base/service-accounts.yaml

@@ -0,0 +1,14 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: control-plane
+  namespace: cosmic-clash
+automountServiceAccountToken: false
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: match-server
+  namespace: cosmic-clash
+automountServiceAccountToken: false
+

multiplayer-next.md

@@ -57,9 +57,11 @@ product policy are in [`docs/MATCHMAKING.md`](docs/MATCHMAKING.md).
 - [x] Complete the threat model for forgery, replay, queue/flood/bot abuse,
   workload/insider compromise, DDoS, supply chain and denial-of-wallet
   ([THREAT-MODEL.md](docs/THREAT-MODEL.md)).
-- [ ] Enforce restricted workloads/RBAC/networks/private stores/backups/secrets;
+- [ ] **IN PROGRESS:** Enforce restricted workloads/RBAC/networks/private
-  isolate SDR signing behind an audited non-exportable signer and add
+  stores/backups/secrets; isolate SDR signing behind an audited non-exportable
-  volumetric edge defense, WebSocket limits and overload shedding.
+  signer and add volumetric edge defense, WebSocket limits and overload
+  shedding. A provider-neutral restricted Kubernetes baseline and structural
+  policy tests now exist; live edge/data-plane controls remain.
 - [ ] Pin, scan, SBOM and sign artifacts; verify signatures at admission and
   document the critical vulnerability SLA.
 

multiplayer-todo.md

@@ -1184,7 +1184,7 @@ the local/CI/community transport, not a silent production fallback.
 | 8.9 `[D:8.4,8.7]` | **IN PROGRESS.** Pure Go join policy binds SteamID/player/match/server/team/slot/protocol/expiry, rejects duplicate roster slots, permits same-identity reclaim through backend loss and fences prior server-owned generations | `server/domain/reconnect.go` covers SteamID/server/slot binding, expiry, repeated reclaim, grace boundary and old-generation fencing; signed token issuance/verification, persistent leases, Godot `hello` transport and production integration remain |
 | 8.10 `[D:8.5,8.31]` | **IN PROGRESS.** Dependency-free workload credential policy validates an adapter-verified signature, issuer/audience/time bounds, namespace/service account, pod UID, GameServer UID, allocation ID, match ID and server ID before result submission | `server/domain/workload.go` and adversarial tests reject every binding mutation, missing/unverified signature and time boundary; `server/testkit/pipeline_test.go` carries allocation identity through the offline result path; projected-token/JWT adapter, trusted-cluster verification and live duplicate/conflict alerting remain |
 | 8.11 `[D:8.1]` | **DONE.** Write the threat model: forged clients/replay/queues/results, floods/bots, pod/insider compromise, gameplay and API DDoS, SDR signing-key theft, dependencies and denial-of-wallet | [`docs/THREAT-MODEL.md`](docs/THREAT-MODEL.md) records prevention, detection/response, owner and residual risk for every threat; it separates offline CA/online signer, client/game-server/PostgreSQL/Redis trust boundaries and recovery behavior |
-| 8.12 `[D:8.11]` | Harden workloads and edge: restricted containers, least RBAC, private DB/Redis, default-deny networks, backups/secrets, volumetric DDoS/WAF/origin shielding, WebSocket limits and overload shedding | Policy/network tests enforce declared flows; edge load test preserves result ingress/live matches while rejecting new work; no credential appears in Git/images/args/telemetry |
+| 8.12 `[D:8.11]` | **IN PROGRESS.** Provider-neutral Kubernetes baseline enforces restricted namespace admission, non-root/read-only/no-capability workloads, separate service accounts, allocator-only RBAC, default-deny networking and explicit edge/data/DNS/Agones flows; application manifests consume externally populated Secret objects | `deploy/k8s/base/` plus `server/security/test_kubernetes_policies.py` cover the static hardening and secret-reference invariants; private-store provisioning, edge DDoS/WAF/origin shielding, WebSocket limits, overload shedding, encrypted backups and live policy/load tests remain |
 | 8.13 `[D:8.12]` | Pin images by digest; generate SBOMs, scan dependencies/images, sign artifacts, verify signatures at admission and document a critical-fix SLA | CI blocks a vulnerable/disallowed or unsigned release artifact and records the exact provenance deployed |
 
 #### 8C — Queueing, matchmaking, playlists and rating

server/security/test_kubernetes_policies.py

@@ -0,0 +1,47 @@
+from pathlib import Path
+import re
+import unittest
+
+
+BASE = Path(__file__).parents[2] / "deploy" / "k8s" / "base"
+
+
+class KubernetesPolicyTest(unittest.TestCase):
+    def read(self, name):
+        return (BASE / name).read_text()
+
+    def test_namespace_enforces_restricted_pod_security(self):
+        namespace = self.read("namespace.yaml")
+        for key in ("enforce", "audit", "warn"):
+            self.assertIn(f"pod-security.kubernetes.io/{key}: restricted", namespace)
+
+    def test_workload_is_non_root_immutable_and_unprivileged(self):
+        deployment = self.read("control-plane-deployment.yaml")
+        for required in (
+            "runAsNonRoot: true", "type: RuntimeDefault", "allowPrivilegeEscalation: false",
+            "readOnlyRootFilesystem: true", "drop: [ALL]", "resources:",
+            "image: ghcr.io/cosmic-clash/control-plane@sha256:",
+        ):
+            self.assertIn(required, deployment)
+        self.assertNotRegex(deployment, r"(?im)^\s*(password|token|private.?key):\s*[^\n]+$")
+        self.assertIn("secretKeyRef:", deployment)
+
+    def test_rbac_is_scoped_to_allocator_create(self):
+        rbac = self.read("rbac.yaml")
+        self.assertIn("namespace: agones-system", rbac)
+        self.assertIn('resources: ["gameserverallocations"]', rbac)
+        self.assertIn('verbs: ["create"]', rbac)
+        self.assertNotRegex(rbac, r"verbs:.*\b(get|list|watch|update|patch|delete|\*)\b")
+        self.assertNotIn('resources: ["*"]', rbac)
+
+    def test_default_deny_and_only_declared_data_dns_edge_flows_exist(self):
+        policies = self.read("network-policies.yaml")
+        self.assertIn("name: default-deny-ingress-egress", policies)
+        self.assertIn("policyTypes: [Ingress, Egress]", policies)
+        for port in ("port: 8080", "port: 5432", "port: 6379", "port: 443", "port: 53"):
+            self.assertIn(port, policies)
+        self.assertNotIn("ipBlock:", policies)
+
+
+if __name__ == "__main__":
+    unittest.main()