Initial generic stock OS device support

GrapheneOS · Aug 8, 2023 · e2c025e · e2c025e
1 parent d8143cc
commit e2c025e
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Showing 2 changed files with 22 additions and 5 deletions.
diff --git a/app/src/main/java/app/attestation/auditor/AttestationProtocol.java b/app/src/main/java/app/attestation/auditor/AttestationProtocol.java
@@ -262,6 +262,11 @@ private static class DeviceInfo {
             this.enforceStrongBox = enforceStrongBox;
             this.osName = osName;
         }
+
+        // Generic device info always have false rollback resistance, and skips boot and vendor patch level checks.
+        boolean isGeneric() {
+            return GENERIC_DEVICE_STOCK.equals(this) || GENERIC_DEVICE_STRONGBOX_STOCK.equals(this);
+        }
     }
 
     private static final boolean isStrongBoxSupported = ImmutableSet.of(
@@ -561,6 +566,13 @@ private static class DeviceInfo {
                     new DeviceInfo(R.string.device_sm_n975u, 3, 4, false, true, R.string.os_stock))
             .build();
 
+    // Some Android 10 devices, including past supported devices above, has attestationVersion, keymasterVersion of 1.
+    // TODO: Remove non-generic device support past EoL with latest Android version lower than Android 10.
+    private static final DeviceInfo GENERIC_DEVICE_STOCK =
+            new DeviceInfo(R.string.generic_device_name_unknown, 1, 1, false, false, R.string.generic_device_os_stock);
+    private static final DeviceInfo GENERIC_DEVICE_STRONGBOX_STOCK =
+            new DeviceInfo(R.string.generic_device_name_unknown, 1, 1, false, true, R.string.generic_device_os_stock);
+
     private static byte[] getChallengeIndex(final Context context) {
         final SharedPreferences global = PreferenceManager.getDefaultSharedPreferences(context);
         final String challengeIndexSerialized = global.getString(KEY_CHALLENGE_INDEX, null);
@@ -733,16 +745,16 @@ private static Verified verifyStateless(final Certificate[] certificates,
             }
         } else if (verifiedBootState == RootOfTrust.VerifiedBootState.VERIFIED) {
             if (attestationSecurityLevelEnum == ParsedAttestationRecord.SecurityLevel.STRONG_BOX) {
-                device = fingerprintsStrongBoxStock.get(verifiedBootKey);
+                device = fingerprintsStrongBoxStock.getOrDefault(verifiedBootKey, GENERIC_DEVICE_STRONGBOX_STOCK);
             } else {
-                device = fingerprintsStock.get(verifiedBootKey);
+                device = fingerprintsStock.getOrDefault(verifiedBootKey, GENERIC_DEVICE_STOCK);
             }
         } else {
             throw new GeneralSecurityException("verified boot state is not verified or self signed");
         }
 
         if (device == null) {
-            throw new GeneralSecurityException("invalid verified boot key fingerprint: " + verifiedBootKey);
+            throw new GeneralSecurityException("invalid self-signed verified boot key fingerprint: " + verifiedBootKey);
         }
 
         // enforce StrongBox for new pairings with devices supporting it
@@ -761,11 +773,13 @@ private static Verified verifyStateless(final Certificate[] certificates,
             throw new GeneralSecurityException("OS patch level too old: " + osPatchLevel);
         }
         final int vendorPatchLevel = teeEnforced.vendorPatchLevel.orElse(0);
-        if (vendorPatchLevel < VENDOR_PATCH_LEVEL_MINIMUM && !extraPatchLevelMissing.contains(device.name)) {
+        if (vendorPatchLevel < VENDOR_PATCH_LEVEL_MINIMUM && !extraPatchLevelMissing.contains(device.name)
+                && !device.isGeneric()) {
             throw new GeneralSecurityException("Vendor patch level too old: " + vendorPatchLevel);
         }
         final int bootPatchLevel = teeEnforced.bootPatchLevel.orElse(0);
-        if (bootPatchLevel < BOOT_PATCH_LEVEL_MINIMUM && !extraPatchLevelMissing.contains(device.name)) {
+        if (bootPatchLevel < BOOT_PATCH_LEVEL_MINIMUM && !extraPatchLevelMissing.contains(device.name)
+                && !device.isGeneric()) {
             throw new GeneralSecurityException("Boot patch level too old: " + bootPatchLevel);
         }
 

diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
@@ -174,4 +174,7 @@
 
     <string name="os_stock">Stock</string>
     <string name="os_graphene">GrapheneOS</string>
+
+    <string name="generic_device_name_unknown">Unknown non-Pixel device</string>
+    <string name="generic_device_os_stock">Stock (Generic)</string>
 </resources>