KM 4 tests for Root-of-Trust

Add tests for device locked state, verfied boot state and VBMeta digest.

Bug: 255344624
Test: VtsHalKeymasterV4_0TargetTest against default impl of KM 4
Change-Id: I46e62ab9031d3745f99bd214f9e579e80edc9128
Merged-In: I46e62ab9031d3745f99bd214f9e579e80edc9128

keymaster/4.0/vts/functional/Android.bp

@@ -30,13 +30,17 @@ cc_test {
         "keymaster_hidl_hal_test.cpp",
     ],
     srcs: [
+        "BootloaderStateTest.cpp",
         "HmacKeySharingTest.cpp",
         "VerificationTokenTest.cpp",
         "keymaster_hidl_hal_test.cpp",
     ],
     static_libs: [
         "android.hardware.keymaster@4.0",
+        "libavb_user",
+        "libavb",
         "libcrypto_static",
+        "libfs_mgr",
         "libkeymaster4support",
         "libkeymaster4vtstest",
     ],
@@ -64,6 +68,7 @@ cc_test_library {
     ],
     static_libs: [
         "android.hardware.keymaster@4.0",
+        "libcrypto_static",
         "libkeymaster4support",
     ],
 }

keymaster/4.0/vts/functional/BootloaderStateTest.cpp

@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <memory>
+#include <optional>
+#include <string>
+#include <vector>
+
+#include <android-base/properties.h>
+#include <fstab/fstab.h>
+#include <libavb/libavb.h>
+#include <libavb_user/avb_ops_user.h>
+
+#include "KeymasterHidlTest.h"
+
+namespace android::hardware::keymaster::V4_0::test {
+
+using ::std::string;
+using ::std::vector;
+
+// Since this test needs to talk to Keymaster HAL, it can only run as root. Thus,
+// bootloader can not be locked.
+class BootloaderStateTest : public KeymasterHidlTest {
+  public:
+    virtual void SetUp() override {
+        KeymasterHidlTest::SetUp();
+
+        // Generate a key.
+        auto ec = GenerateKey(AuthorizationSetBuilder()
+                                      .Authorization(TAG_NO_AUTH_REQUIRED)
+                                      .EcdsaSigningKey(EcCurve::P_256)
+                                      .Digest(Digest::SHA_2_256));
+        ASSERT_EQ(ec, ErrorCode::OK) << "Failed to generate key.";
+
+        // Generate attestation.
+        hidl_vec<hidl_vec<uint8_t>> cert_chain;
+        ec = AttestKey(AuthorizationSetBuilder()
+                               .Authorization(TAG_ATTESTATION_CHALLENGE, HidlBuf("challenge"))
+                               .Authorization(TAG_ATTESTATION_APPLICATION_ID, HidlBuf("foo")),
+                       &cert_chain);
+        ASSERT_EQ(ec, ErrorCode::OK) << "Failed to generate attestation.";
+
+        X509_Ptr cert(parse_cert_blob(cert_chain[0]));
+        ASSERT_TRUE(cert.get()) << "Failed to parse certificate blob.";
+
+        ASN1_OCTET_STRING* attest_rec = get_attestation_record(cert.get());
+        ASSERT_TRUE(attest_rec) << "Failed to get attestation record.";
+
+        // Parse root of trust.
+        HidlBuf verified_boot_key;
+        keymaster_verified_boot_t verified_boot_state;
+        bool device_locked;
+        HidlBuf verified_boot_hash;
+        auto result =
+                parse_root_of_trust(attest_rec->data, attest_rec->length, &verified_boot_key,
+                                    &verified_boot_state, &device_locked, &verified_boot_hash);
+        ASSERT_EQ(result, ErrorCode::OK) << "Failed to parse root of trust.";
+    }
+
+    hidl_vec<uint8_t> attestedVbKey_;
+    keymaster_verified_boot_t attestedVbState_;
+    bool attestedBootloaderState_;
+    hidl_vec<uint8_t> attestedVbmetaDigest_;
+};
+
+// Check that attested bootloader state is set to unlocked.
+TEST_P(BootloaderStateTest, BootloaderIsUnlocked) {
+    ASSERT_FALSE(attestedBootloaderState_)
+            << "This test runs as root. Bootloader must be unlocked.";
+}
+
+// Check that verified boot state is set to "unverified", i.e. "orange".
+TEST_P(BootloaderStateTest, VbStateIsUnverified) {
+    // Unlocked bootloader implies that verified boot state must be "unverified".
+    ASSERT_EQ(attestedVbState_, KM_VERIFIED_BOOT_UNVERIFIED)
+            << "Verified boot state must be \"UNVERIFIED\" aka \"orange\".";
+
+    // AVB spec stipulates that bootloader must set "androidboot.verifiedbootstate" parameter
+    // on the kernel command-line. This parameter is exposed to userspace as
+    // "ro.boot.verifiedbootstate" property.
+    auto vbStateProp = ::android::base::GetProperty("ro.boot.verifiedbootstate", "");
+    ASSERT_EQ(vbStateProp, "orange")
+            << "Verified boot state must be \"UNVERIFIED\" aka \"orange\".";
+}
+
+// Following error codes from avb_slot_data() mean that slot data was loaded
+// (even if verification failed).
+static inline bool avb_slot_data_loaded(AvbSlotVerifyResult result) {
+    switch (result) {
+        case AVB_SLOT_VERIFY_RESULT_OK:
+        case AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION:
+        case AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX:
+        case AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED:
+            return true;
+        default:
+            return false;
+    }
+}
+
+// Check that attested vbmeta digest is correct.
+TEST_P(BootloaderStateTest, VbmetaDigest) {
+    AvbSlotVerifyData* avbSlotData;
+    auto suffix = fs_mgr_get_slot_suffix();
+    const char* partitions[] = {nullptr};
+    auto avbOps = avb_ops_user_new();
+
+    // For VTS, devices run with vendor_boot-debug.img, which is not release key
+    // signed. Use AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR to bypass avb
+    // verification errors. This is OK since we only care about the digest for
+    // this test case.
+    auto result = avb_slot_verify(avbOps, partitions, suffix.c_str(),
+                                  AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR,
+                                  AVB_HASHTREE_ERROR_MODE_EIO, &avbSlotData);
+    ASSERT_TRUE(avb_slot_data_loaded(result)) << "Failed to load avb slot data";
+
+    // Unfortunately, bootloader is not required to report the algorithm used
+    // to calculate the digest. There are only two supported options though,
+    // SHA256 and SHA512. Attested VBMeta digest must match one of these.
+    vector<uint8_t> digest256(AVB_SHA256_DIGEST_SIZE);
+    vector<uint8_t> digest512(AVB_SHA512_DIGEST_SIZE);
+
+    avb_slot_verify_data_calculate_vbmeta_digest(avbSlotData, AVB_DIGEST_TYPE_SHA256,
+                                                 digest256.data());
+    avb_slot_verify_data_calculate_vbmeta_digest(avbSlotData, AVB_DIGEST_TYPE_SHA512,
+                                                 digest512.data());
+
+    ASSERT_TRUE((attestedVbmetaDigest_ == digest256) || (attestedVbmetaDigest_ == digest512))
+            << "Attested digest does not match computed digest.";
+}
+
+INSTANTIATE_KEYMASTER_HIDL_TEST(BootloaderStateTest);
+
+}  // namespace android::hardware::keymaster::V4_0::test

keymaster/4.0/vts/functional/KeymasterHidlTest.cpp

@@ -841,6 +841,30 @@ std::vector<Digest> KeymasterHidlTest::InvalidDigests() {
     return {};
 }
 
+X509* parse_cert_blob(const hidl_vec<uint8_t>& blob) {
+    const uint8_t* p = blob.data();
+    return d2i_X509(nullptr, &p, blob.size());
+}
+
+ASN1_OCTET_STRING* get_attestation_record(X509* certificate) {
+    ASN1_OBJECT_Ptr oid(OBJ_txt2obj(kAttestionRecordOid, 1 /* dotted string format */));
+    EXPECT_TRUE(!!oid.get());
+    if (!oid.get()) return nullptr;
+
+    int location = X509_get_ext_by_OBJ(certificate, oid.get(), -1 /* search from beginning */);
+    EXPECT_NE(-1, location) << "Attestation extension not found in certificate";
+    if (location == -1) return nullptr;
+
+    X509_EXTENSION* attest_rec_ext = X509_get_ext(certificate, location);
+    EXPECT_TRUE(!!attest_rec_ext)
+            << "Found attestation extension but couldn't retrieve it?  Probably a BoringSSL bug.";
+    if (!attest_rec_ext) return nullptr;
+
+    ASN1_OCTET_STRING* attest_rec = X509_EXTENSION_get_data(attest_rec_ext);
+    EXPECT_TRUE(!!attest_rec) << "Attestation extension contained no data";
+    return attest_rec;
+}
+
 }  // namespace test
 }  // namespace V4_0
 }  // namespace keymaster

keymaster/4.0/vts/functional/KeymasterHidlTest.h

@@ -22,7 +22,9 @@
 #include <hidl/GtestPrinter.h>
 #include <hidl/ServiceManagement.h>
 
+#include <keymasterV4_0/attestation_record.h>
 #include <keymasterV4_0/authorization_set.h>
+#include <keymasterV4_0/openssl_utils.h>
 
 namespace android {
 namespace hardware {
@@ -241,6 +243,11 @@ class KeymasterHidlTest : public ::testing::TestWithParam<std::string> {
                              testing::ValuesIn(KeymasterHidlTest::build_params()), \
                              android::hardware::PrintInstanceNameToString)
 
+X509* parse_cert_blob(const hidl_vec<uint8_t>& blob);
+// Extract attestation record from cert. Returned object is still part of cert; don't free it
+// separately.
+ASN1_OCTET_STRING* get_attestation_record(X509* certificate);
+
 }  // namespace test
 }  // namespace V4_0
 }  // namespace keymaster

keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp

@@ -263,11 +263,6 @@ struct RSA_Delete {
     void operator()(RSA* p) { RSA_free(p); }
 };
 
-X509* parse_cert_blob(const hidl_vec<uint8_t>& blob) {
-    const uint8_t* p = blob.data();
-    return d2i_X509(nullptr, &p, blob.size());
-}
-
 bool verify_chain(const hidl_vec<hidl_vec<uint8_t>>& chain, const std::string& msg,
                   const std::string& signature) {
     {
@@ -337,27 +332,6 @@ bool verify_chain(const hidl_vec<hidl_vec<uint8_t>>& chain, const std::string& m
     return true;
 }
 
-// Extract attestation record from cert. Returned object is still part of cert; don't free it
-// separately.
-ASN1_OCTET_STRING* get_attestation_record(X509* certificate) {
-    ASN1_OBJECT_Ptr oid(OBJ_txt2obj(kAttestionRecordOid, 1 /* dotted string format */));
-    EXPECT_TRUE(!!oid.get());
-    if (!oid.get()) return nullptr;
-
-    int location = X509_get_ext_by_OBJ(certificate, oid.get(), -1 /* search from beginning */);
-    EXPECT_NE(-1, location) << "Attestation extension not found in certificate";
-    if (location == -1) return nullptr;
-
-    X509_EXTENSION* attest_rec_ext = X509_get_ext(certificate, location);
-    EXPECT_TRUE(!!attest_rec_ext)
-        << "Found attestation extension but couldn't retrieve it?  Probably a BoringSSL bug.";
-    if (!attest_rec_ext) return nullptr;
-
-    ASN1_OCTET_STRING* attest_rec = X509_EXTENSION_get_data(attest_rec_ext);
-    EXPECT_TRUE(!!attest_rec) << "Attestation extension contained no data";
-    return attest_rec;
-}
-
 bool tag_in_list(const KeyParameter& entry) {
     // Attestations don't contain everything in key authorization lists, so we need to filter
     // the key lists to produce the lists that we expect to match the attestations.