docs: add no privilege escalation to the restricted hardening posture

docs/adr/model/0020-hardening-is-one-platform-posture.md

@@ -29,10 +29,11 @@ listed in [chapter 10](../../../spec/v1/10-project-intent.md#hardening).
 
 ## Rests on
 
-Kubernetes applies the four controls (non-root, an immutable root filesystem, no
-capabilities, the default syscall filter) per pod and per container
+Kubernetes applies the five controls (non-root, an immutable root filesystem, no
+capabilities, no privilege escalation, the default syscall filter) per pod and
+per container
 ([0002](0002-kubernetes-is-the-substrate-for-one-applier.md)), so the render can
-state all four on every container with no author involved. Ephemeral disk is
+state all five on every container with no author involved. Ephemeral disk is
 contended, so its size is platform-assigned
 ([0004](0004-contention-decides-authority.md)). The lock is a pinned input
 ([0006](0006-pinned-inputs.md)), so a user read from it is a derivation, not a
@@ -42,7 +43,7 @@ registry read at render time.
 exception to render, a Process's writable set cannot be enumerated ahead of
 time, or an image the estate depends on has no numeric user and cannot be
 replaced. **Settled by:** the committed trees under
-`spec/v1/examples/{auth,data,knowledge,minimal}/rendered/` carrying the four
+`spec/v1/examples/{auth,data,knowledge,minimal}/rendered/` carrying the five
 controls on every container, the `postgres-exporter` sidecar included, with no
 project file carrying a hardening field (a test asserting both is to be
 written, owned by joris); and `platform-postgres` running `initdb` on a freshly
@@ -71,6 +72,13 @@ A fresh `local-path` directory is root-owned, so a non-root pod with no
 to resolve a digest, so it reads the user too. An init container that chowns the
 volume would need root on every stateful Process.
 
+**Privilege escalation is closed, not implied.** Non-root with every capability
+dropped still lets a setuid binary in the image raise its process to uid 0;
+`allowPrivilegeEscalation: false` sets `no_new_privs` and closes that. It is
+also one of the controls Kubernetes' own `restricted` Pod Security Standard
+requires, so a posture under that name without it would be refused by a
+namespace enforcing the standard.
+
 **A low port is refused.** `auth-ui` declared port 80 under `restricted` and
 rendered a pod that could not bind it. Deriving `NET_BIND_SERVICE` would re-add a
 dropped capability silently. A route names a surface, not a number

spec/v1/10-project-intent.md

@@ -1149,14 +1149,15 @@ The posture itself is **not authored per Process**. It is one estate-wide value,
 it thirty times would be restating the only value there is, and a field with one
 legal value carries no information ([0022](../../docs/adr/model/0022-a-derived-value-has-one-declaring-site.md)
 deleted `minAvailable` for the same reason). What a Process authors is the
-paths it must write, and nothing else. `restricted` is four controls, applied
+paths it must write, and nothing else. `restricted` is five controls, applied
 together:
 
 | control | rendered as |
 |---|---|
 | non-root | `runAsNonRoot: true`, with the numeric UID the images lock resolved ([0020](../../docs/adr/model/0020-hardening-is-one-platform-posture.md)) |
 | immutable root filesystem | `readOnlyRootFilesystem: true` |
 | no capabilities | `capabilities.drop: [ALL]` |
+| no privilege escalation | `allowPrivilegeEscalation: false` |
 | default syscall filter | `seccompProfile.type: RuntimeDefault` |
 
 ### Writable paths are declared, not exempted

spec/v1/20-resolved-deployment.md

@@ -657,8 +657,8 @@ Five rules carry most of the weight:
   with different volumes, which is the property that makes a restore rehearsal
   meaningful ([0018](../../docs/adr/model/0018-durability-class-derives-a-backup.md)).
 - **Hardening is one platform posture, and nothing else.** `restricted` (
-  `runAsNonRoot`, `readOnlyRootFilesystem`, all capabilities dropped, seccomp
-  `RuntimeDefault`) is declared once in the Platform document and authored by no
+  `runAsNonRoot`, `readOnlyRootFilesystem`, all capabilities dropped, no
+  privilege escalation, seccomp `RuntimeDefault`) is declared once in the Platform document and authored by no
   Process. There is no per-control relaxation and no exception vocabulary: a
   Process declares the paths it must write, and an image that cannot meet the
   class is `E_HARDENING_UNMET`

spec/v1/30-deliverables.md

@@ -330,7 +330,7 @@ spells only what the projection holds:
 | the `secretStore` endpoint | `vso` | a `VaultConnection` named `secret-store` in the project's namespace, at that address, `skipTLSVerify: false` |
 | a grant delivered `env` or `file` | `vso` | a `VaultAuth` per holding identity, its `ServiceAccount` that identity and its role `<namespace>-<identity>`, over the `secret-store` connection; a `VaultStaticSecret` named for the `destination`, `kv-v2` on the `secret` mount at the path below `secret/data/`, `refreshAfter: 1h`, its destination created and `flagger.app/config-tracking: disabled`, each restart target a `Deployment`, a `blue-green` Process's `-primary` |
 | a `read` grant | `vault-policy` | `read` on its path and on the same document's `secret/metadata/` path |
-| `hardening: restricted` | `kubernetes` | `runAsNonRoot`, the images lock's `uid` and `gid`, seccomp `RuntimeDefault`, a read-only root filesystem, every capability dropped |
+| `hardening: restricted` | `kubernetes` | `runAsNonRoot`, the images lock's `uid` and `gid`, seccomp `RuntimeDefault`, a read-only root filesystem, every capability dropped, `allowPrivilegeEscalation: false` |
 | a probe's `period`, `timeout`, `failures` | `kubernetes` | `periodSeconds`, `timeoutSeconds`, `failureThreshold`; `initialDelaySeconds: 0` on readiness and liveness only |
 | `ingress`, `egress`, an edge's `peers` | `networking` | one rule per peer, from or to its namespace (by `kubernetes.io/metadata.name`) and, where the peer is a Process, its `instance`, on TCP; the `cluster-dns` peer on UDP and TCP both |
 | a held `api`'s `server` | `networking` | one egress rule per range in the Process's own policy, after its peers, to an `ipBlock` of its `cidr` on its port over TCP |