From bf655ec7a16b98d75c5090e5446818773dcf6c52 Mon Sep 17 00:00:00 2001
From: Kevin Wang <wy721@qq.com>
Date: Sat, 19 Sep 2026 21:42:40 -0700
Subject: [PATCH] fix(kms): deny on an empty device allowlist in auth-simple

---
 dstack/kms/auth-simple/README.md     |  4 +--
 dstack/kms/auth-simple/index.test.ts | 46 ++++++++++++++++++++++++++++
 dstack/kms/auth-simple/index.ts      |  4 +--
 3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/dstack/kms/auth-simple/README.md b/dstack/kms/auth-simple/README.md
index 6857122d1..efd2efcb5 100644
--- a/dstack/kms/auth-simple/README.md
+++ b/dstack/kms/auth-simple/README.md
@@ -102,10 +102,10 @@ raw NitroTPM evidence by itself.
 | `allowedTcbStatuses` | No | Allowed verifier-derived TCB status strings. Defaults to `["UpToDate"]`; non-up-to-date SNP/TDX statuses remain fail-closed unless explicitly allowlisted for testing. |
 | `allowedAdvisoryIds` | No | Advisory IDs permitted in `advisoryIds`. Defaults to `[]`, which rejects any advisory. |
 | `kms.mrAggregated` | Yes | Allowed KMS early aggregate MR values (boot-mr-done). |
-| `kms.devices` | No | Allowed KMS device IDs |
+| `kms.devices` | No | Allowed KMS device IDs. Empty denies all unless `kms.allowAnyDevice` is true. |
 | `kms.allowAnyDevice` | No | If true, skip device ID check for KMS |
 | `apps.<appId>.composeHashes` | No | Allowed compose hashes for this app |
-| `apps.<appId>.devices` | No | Allowed device IDs for this app |
+| `apps.<appId>.devices` | No | Allowed device IDs for this app. Empty denies all unless `allowAnyDevice` is true. |
 | `apps.<appId>.allowAnyDevice` | No | If true, skip device ID check for this app |
 
 For experimental AMD SEV-SNP dry-run authorization, keep the default fail-closed TCB policy unless you intentionally want the auth webhook to accept non-up-to-date verifier-derived SNP `BootInfo`. To exercise the dry-run path without enabling key release, allowlist the recomputed SNP `mrAggregated`, `osImageHash`, app/compose identity, device/chip identity, and any non-default `allowedTcbStatuses`/`allowedAdvisoryIds` values explicitly. KMS still rejects SNP before returning app keys, KMS keys, or app certificates.
diff --git a/dstack/kms/auth-simple/index.test.ts b/dstack/kms/auth-simple/index.test.ts
index 32ad06772..8d1ca4309 100644
--- a/dstack/kms/auth-simple/index.test.ts
+++ b/dstack/kms/auth-simple/index.test.ts
@@ -240,6 +240,28 @@ describe('auth-simple', () => {
       expect(json.isAllowed).toBe(false);
       expect(json.reason).toContain('MR');
     });
+    it('rejects KMS boot with an empty device allowlist', async () => {
+      writeTestConfig({
+        gatewayAppId: '0xgateway',
+        osImages: ['0x1fbb0cf9cc6cfbf23d6b779776fabad2c5403d643badb9e5e238615e4960a78a'],
+        kms: {
+          mrAggregated: ['0xabc123'],
+          devices: [],
+          allowAnyDevice: false
+        }
+      });
+
+      const res = await app.fetch(new Request('http://localhost/bootAuth/kms', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(baseBootInfo)
+      }));
+      const json = await res.json();
+
+      expect(json.isAllowed).toBe(false);
+      expect(json.reason).toContain('device');
+    });
+
     it('allows KMS boot with allowAnyDevice', async () => {
       writeTestConfig({
         gatewayAppId: '0xgateway',
@@ -352,6 +374,30 @@ describe('auth-simple', () => {
       expect(json.reason).toContain('device');
     });
 
+    it('rejects app boot with an empty device allowlist', async () => {
+      writeTestConfig({
+        gatewayAppId: '0xgateway',
+        osImages: ['0x1fbb0cf9cc6cfbf23d6b779776fabad2c5403d643badb9e5e238615e4960a78a'],
+        apps: {
+          '0xapp123': {
+            composeHashes: ['0xcompose456'],
+            devices: [],
+            allowAnyDevice: false
+          }
+        }
+      });
+
+      const res = await app.fetch(new Request('http://localhost/bootAuth/app', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(baseBootInfo)
+      }));
+      const json = await res.json();
+
+      expect(json.isAllowed).toBe(false);
+      expect(json.reason).toContain('device');
+    });
+
     it('allows app boot with allowAnyDevice', async () => {
       writeTestConfig({
         gatewayAppId: '0xgateway',
diff --git a/dstack/kms/auth-simple/index.ts b/dstack/kms/auth-simple/index.ts
index 4a833d1ec..7f9a7f036 100644
--- a/dstack/kms/auth-simple/index.ts
+++ b/dstack/kms/auth-simple/index.ts
@@ -149,7 +149,7 @@ class ConfigBackend {
     // check device ID
     if (!config.kms.allowAnyDevice) {
       const allowedDevices = config.kms.devices.map(normalizeHex);
-      if (allowedDevices.length > 0 && !allowedDevices.includes(deviceId)) {
+      if (!allowedDevices.includes(deviceId)) {
         return {
           isAllowed: false,
           reason: 'KMS is not allowed to boot on this device',
@@ -195,7 +195,7 @@ class ConfigBackend {
     // check device ID
     if (!appConfig.allowAnyDevice) {
       const allowedDevices = appConfig.devices.map(normalizeHex);
-      if (allowedDevices.length > 0 && !allowedDevices.includes(deviceId)) {
+      if (!allowedDevices.includes(deviceId)) {
         return {
           isAllowed: false,
           reason: 'app is not allowed to boot on this device',