fix(distribution): permit fixed secret read during init

Plan: .omo/plans/baota-ai-ops-control-plane.md

Author: cat9999aaa

apps/daemon/src/runtime/__test__/docker-runtime-security.test.ts

@@ -114,10 +114,10 @@ describe("Docker runtime security", () => {
     });
     const callerPathInvoked = existsSync(tracePath);
     await rm(fixtureDirectory, { recursive: true });
-    const capAddBlock = /^\s{4}cap_add:\n((?:\s{6}-\s+"[A-Z]+"\n)+)/mu.exec(
+    const capAddBlock = /^\s{4}cap_add:\n((?:\s{6}-\s+"[A-Z_]+"\n)+)/mu.exec(
       compose,
     );
-    const startupCapabilities = capAddBlock?.[1]?.match(/[A-Z]+/gu) ?? [];
+    const startupCapabilities = capAddBlock?.[1]?.match(/[A-Z_]+/gu) ?? [];
     const dockerMarkers = [
       "COPY scripts/container-entrypoint.sh /usr/local/bin/container-entrypoint.sh",
       "chmod 0755 /usr/local/bin/container-entrypoint.sh",
@@ -148,9 +148,15 @@ describe("Docker runtime security", () => {
       [...bootstrapMarkers].sort((left, right) => left - right),
     );
 
-    // Linux clears permitted/effective capabilities on uid 0 -> 1000;
+    // DAC_OVERRIDE is consumed only to read Docker's root-owned file secret.
+    // Linux then clears permitted/effective capabilities on uid 0 -> 1000;
     // no-new-privileges and the absence of file capabilities prevent reacquisition.
-    expect(startupCapabilities).toEqual(["CHOWN", "SETUID", "SETGID"]);
+    expect(startupCapabilities).toEqual([
+      "CHOWN",
+      "SETUID",
+      "SETGID",
+      "DAC_OVERRIDE",
+    ]);
     expect(compose).toMatch(/^\s{4}cap_drop:\n\s{6}- "ALL"$/mu);
     expect(compose).toMatch(
       /^\s{4}security_opt:\n\s{6}- "no-new-privileges:true"$/mu,

compose.yaml

@@ -6,12 +6,14 @@ services:
     read_only: true
     cap_drop:
       - "ALL"
-    # The fixed entrypoint consumes these only for its data-mount chown and
-    # uid/gid transition before exec; the daemon starts with no capabilities.
+    # The fixed entrypoint consumes DAC_OVERRIDE only to read Docker's
+    # root-owned file secret, CHOWN for the fixed data mount, and SETUID/SETGID
+    # for its uid/gid transition; the daemon starts with no capabilities.
     cap_add:
       - "CHOWN"
       - "SETUID"
       - "SETGID"
+      - "DAC_OVERRIDE"
     security_opt:
       - "no-new-privileges:true"
     pids_limit: 256