RC-9-A: Bugfix

TESTING.md

@@ -473,3 +473,10 @@ without the application's external Go dependencies:
 ```bash
 go test ./internal/customer/docker.go ./internal/customer/docker_test.go
 ```
+
+## V4.2.5 worker identity-volume migration check
+
+After publishing the new worker image, start a hosted worker that already owns
+an identity volume from an older release. It must start without `permission
+denied`, keep the same client identity, and remain writable at
+`/identity/identity.json`. Do not delete the named volume for this test.

V4.2.5_WORKER_IDENTITY_PERMISSION_FIX.md

@@ -0,0 +1,24 @@
+# V4.2.5 – Worker identity volume permission fix
+
+Managed workers persist `/identity/identity.json` in a Docker named volume. A
+new named volume is normally root-owned, while identities from older releases
+may already be mode `0600` and owned by a different UID. With the hardened
+worker capability set this could make the client fail immediately with:
+
+```
+open /identity/identity.json: permission denied
+```
+
+V4.2.5 makes the worker image normalize only `/identity` and the fixed
+`/identity/identity.json` path before startup. The entrypoint starts as root,
+fixes ownership, and immediately executes `/app/neuralhunt-client` as the
+unprivileged `app` user via `su-exec`.
+
+Customer Service still drops all Linux capabilities and adds back only the four
+bootstrap capabilities needed by that entrypoint: `CHOWN`, `DAC_OVERRIDE`,
+`SETUID`, and `SETGID`. Workers still receive no Docker socket and retain a
+read-only root filesystem.
+
+Existing worker identity volumes are intentionally kept. Rebuilding/pulling the
+worker image and restarting an affected worker is sufficient; deleting the
+worker/volume would destroy its identity and is not required.

docker/worker-entrypoint.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+set -eu
+
+# Docker named volumes are normally created as root:root. Older Neural Hunt
+# worker versions could also leave identity.json owned by a different UID.
+# Normalize only the dedicated identity mount and the fixed identity file, then
+# permanently drop to the unprivileged app user before the Go client starts.
+if [ "$(id -u)" = "0" ]; then
+    if [ -L /identity/identity.json ]; then
+        echo "refusing symlink at /identity/identity.json" >&2
+        exit 1
+    fi
+
+    chown app:app /identity
+    if [ -e /identity/identity.json ]; then
+        chown app:app /identity/identity.json
+    fi
+
+    exec su-exec app:app /app/neuralhunt-client "$@"
+fi
+
+exec /app/neuralhunt-client "$@"

internal/customer/docker.go

@@ -210,10 +210,10 @@ func (d *DockerClient) CreateWorker(ctx context.Context, c WorkerContainerConfig
 	name := url.QueryEscape(c.Name)
 	body := map[string]any{
 		"Image": c.Image,
-		// Named Docker volumes are root-owned when first mounted. Managed workers
-		// therefore run uid 0 only inside their own locked-down container so they
-		// can create the 0600 identity file. They receive no Docker socket, all
-		// Linux capabilities are dropped and the image root filesystem is read-only.
+		// Named Docker volumes are root-owned when first mounted, and identities
+		// created by older releases may be owned by a different UID. The dedicated
+		// worker image starts as uid 0 only for its tiny ownership-normalization
+		// entrypoint and immediately drops to the unprivileged app user.
 		"User": "0:0",
 		"Cmd":  []string{"-url", c.GameURL, "-identity", "/identity/identity.json", "-non-interactive", "-quiet", "-task", c.TaskID, "-beacon-path", c.BeaconPath},
 		"Env": []string{
@@ -228,10 +228,13 @@ func (d *DockerClient) CreateWorker(ctx context.Context, c WorkerContainerConfig
 			"NetworkMode":    c.Network,
 			"ReadonlyRootfs": true,
 			"CapDrop":        []string{"ALL"},
-			"SecurityOpt":    []string{"no-new-privileges"},
-			"PidsLimit":      128,
-			"Memory":         256 * 1024 * 1024,
-			"NanoCpus":       int64(1_000_000_000),
+			// Bootstrap-only capabilities: the image entrypoint fixes ownership of
+			// /identity and then su-exec permanently switches to uid/gid app.
+			"CapAdd":      []string{"CHOWN", "DAC_OVERRIDE", "SETUID", "SETGID"},
+			"SecurityOpt": []string{"no-new-privileges"},
+			"PidsLimit":   128,
+			"Memory":      256 * 1024 * 1024,
+			"NanoCpus":    int64(1_000_000_000),
 		},
 	}
 	// A dedicated worker image already declares /app/neuralhunt-client as its