Allow attest to device properties
Attesting (only) to device properties is allowed without special
permission (android.permission.READ_PRIVILEGED_PHONE_STATE) since
base device properties should be accessible to everyone. For
unique identifying IDs attestation the permission is still needed.
Test: atest CtsKeystoreTestCases
Bug: 152945378
Change-Id: I8395e0c18cfc91916a172d20dd6049c7c027e8d9
diff --git a/keystore/key_store_service.cpp b/keystore/key_store_service.cpp
index 666b48a..e766182 100644
--- a/keystore/key_store_service.cpp
+++ b/keystore/key_store_service.cpp
@@ -961,21 +961,102 @@
return Status::ok();
}
+bool isDeviceIdAttestationTag(Tag tag) {
+ switch (tag) {
+ case Tag::ATTESTATION_ID_BRAND:
+ case Tag::ATTESTATION_ID_DEVICE:
+ case Tag::ATTESTATION_ID_MANUFACTURER:
+ case Tag::ATTESTATION_ID_MODEL:
+ case Tag::ATTESTATION_ID_PRODUCT:
+ case Tag::ATTESTATION_ID_IMEI:
+ case Tag::ATTESTATION_ID_MEID:
+ case Tag::ATTESTATION_ID_SERIAL:
+ return true;
+ case Tag::INVALID:
+ case Tag::PURPOSE:
+ case Tag::ALGORITHM:
+ case Tag::KEY_SIZE:
+ case Tag::BLOCK_MODE:
+ case Tag::DIGEST:
+ case Tag::PADDING:
+ case Tag::CALLER_NONCE:
+ case Tag::MIN_MAC_LENGTH:
+ case Tag::EC_CURVE:
+ case Tag::RSA_PUBLIC_EXPONENT:
+ case Tag::INCLUDE_UNIQUE_ID:
+ case Tag::BLOB_USAGE_REQUIREMENTS:
+ case Tag::BOOTLOADER_ONLY:
+ case Tag::ROLLBACK_RESISTANCE:
+ case Tag::HARDWARE_TYPE:
+ case Tag::ACTIVE_DATETIME:
+ case Tag::ORIGINATION_EXPIRE_DATETIME:
+ case Tag::USAGE_EXPIRE_DATETIME:
+ case Tag::MIN_SECONDS_BETWEEN_OPS:
+ case Tag::MAX_USES_PER_BOOT:
+ case Tag::USER_ID:
+ case Tag::USER_SECURE_ID:
+ case Tag::NO_AUTH_REQUIRED:
+ case Tag::USER_AUTH_TYPE:
+ case Tag::AUTH_TIMEOUT:
+ case Tag::ALLOW_WHILE_ON_BODY:
+ case Tag::TRUSTED_USER_PRESENCE_REQUIRED:
+ case Tag::TRUSTED_CONFIRMATION_REQUIRED:
+ case Tag::UNLOCKED_DEVICE_REQUIRED:
+ case Tag::APPLICATION_ID:
+ case Tag::APPLICATION_DATA:
+ case Tag::CREATION_DATETIME:
+ case Tag::ORIGIN:
+ case Tag::ROOT_OF_TRUST:
+ case Tag::OS_VERSION:
+ case Tag::OS_PATCHLEVEL:
+ case Tag::UNIQUE_ID:
+ case Tag::ATTESTATION_CHALLENGE:
+ case Tag::ATTESTATION_APPLICATION_ID:
+ case Tag::VENDOR_PATCHLEVEL:
+ case Tag::BOOT_PATCHLEVEL:
+ case Tag::ASSOCIATED_DATA:
+ case Tag::NONCE:
+ case Tag::MAC_LENGTH:
+ case Tag::RESET_SINCE_ID_ROTATION:
+ case Tag::CONFIRMATION_TOKEN:
+ return false;
+ // no default, all values must be present in the switch, in this way the compiler ensures
+ // that new values added in the Tag enum are also added here.
+ }
+}
+
+// These are attestation id tags that are not unique per device and don't require special permission
+// to be attested. Any addition to this list needs privacy review and approval (PWG).
+bool isDevicePropertyAttestationTag(Tag tag) {
+ switch (tag) {
+ case Tag::ATTESTATION_ID_BRAND:
+ case Tag::ATTESTATION_ID_DEVICE:
+ case Tag::ATTESTATION_ID_MANUFACTURER:
+ case Tag::ATTESTATION_ID_MODEL:
+ case Tag::ATTESTATION_ID_PRODUCT:
+ return true;
+ default:
+ return false;
+ }
+}
+
bool isDeviceIdAttestationRequested(const KeymasterArguments& params) {
const hardware::hidl_vec<KeyParameter>& paramsVec = params.getParameters();
for (size_t i = 0; i < paramsVec.size(); ++i) {
- switch (paramsVec[i].tag) {
- case Tag::ATTESTATION_ID_BRAND:
- case Tag::ATTESTATION_ID_DEVICE:
- case Tag::ATTESTATION_ID_MANUFACTURER:
- case Tag::ATTESTATION_ID_MODEL:
- case Tag::ATTESTATION_ID_PRODUCT:
- case Tag::ATTESTATION_ID_IMEI:
- case Tag::ATTESTATION_ID_MEID:
- case Tag::ATTESTATION_ID_SERIAL:
+ if (isDeviceIdAttestationTag(paramsVec[i].tag)) {
return true;
- default:
- continue;
+ }
+ }
+ return false;
+}
+
+// Device properties can be attested safely without special permission
+bool needsPermissionToAttestDeviceIds(const KeymasterArguments& params) {
+ const hardware::hidl_vec<KeyParameter>& paramsVec = params.getParameters();
+ for (size_t i = 0; i < paramsVec.size(); ++i) {
+ if (isDeviceIdAttestationTag(paramsVec[i].tag) &&
+ !isDevicePropertyAttestationTag(paramsVec[i].tag)) {
+ return true;
}
}
return false;
@@ -1055,14 +1136,19 @@
}
uid_t callingUid = IPCThreadState::self()->getCallingUid();
- sp<IBinder> binder = defaultServiceManager()->getService(String16("permission"));
- if (binder == nullptr) {
- return AIDL_RETURN(ErrorCode::CANNOT_ATTEST_IDS);
- }
- if (!interface_cast<IPermissionController>(binder)->checkPermission(
- String16("android.permission.READ_PRIVILEGED_PHONE_STATE"),
- IPCThreadState::self()->getCallingPid(), callingUid)) {
- return AIDL_RETURN(ErrorCode::CANNOT_ATTEST_IDS);
+
+ // Request special permission only for unique ids
+ if (needsPermissionToAttestDeviceIds(params)) {
+ sp<IBinder> binder = defaultServiceManager()->getService(String16("permission"));
+ if (binder == nullptr) {
+ return AIDL_RETURN(ErrorCode::CANNOT_ATTEST_IDS);
+ }
+
+ if (!interface_cast<IPermissionController>(binder)->checkPermission(
+ String16("android.permission.READ_PRIVILEGED_PHONE_STATE"),
+ IPCThreadState::self()->getCallingPid(), callingUid)) {
+ return AIDL_RETURN(ErrorCode::CANNOT_ATTEST_IDS);
+ }
}
AuthorizationSet mutableParams = params.getParameters();