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Implement alternate SE RoT provisioning

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Bug: 219076736
Test: VtsAidlKeyMintTargetTest
Change-Id: Ia696d7765f316d35eba1b4e65acae6c1072987b1
This commit is contained in:
Shawn Willden 2022-03-20 12:49:46 -06:00
parent 7fc26b99d3
commit 4315e135c6
4 changed files with 147 additions and 68 deletions
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4
security/keymint/aidl/android/hardware/security/keymint/IKeyMintDevice.aidl
View file

@ -873,7 +873,7 @@ interface IKeyMintDevice {
* The returned data is an encoded COSE_Mac0 structure, denoted MacedRootOfTrust in the
* following CDDL schema. Note that K_mac is the shared HMAC key used for auth tokens, etc.:
*
* MacedRootOfTrust = [ ; COSE_Mac0 (untagged)
* MacedRootOfTrust = #6.17 [ ; COSE_Mac0 (tagged)
* protected: bstr .cbor {
* 1 : 5, ; Algorithm : HMAC-256
* },
@ -891,7 +891,7 @@ interface IKeyMintDevice {
* payload : bstr .cbor RootOfTrust,
* ]
*
* RootOfTrust = [
* RootOfTrust = #6.40001 [ ; Tag 40001 indicates RoT v1.
* verifiedBootKey : bstr .size 32,
* deviceLocked : bool,
* verifiedBootState : &VerifiedBootState,

106
security/keymint/aidl/vts/functional/KeyMintAidlTestBase.cpp
View file

@ -31,7 +31,6 @@
#include <remote_prov/remote_prov_utils.h>
#include <keymaster/cppcose/cppcose.h>
#include <keymint_support/attestation_record.h>
#include <keymint_support/key_param_output.h>
#include <keymint_support/keymint_utils.h>
#include <keymint_support/openssl_utils.h>
@ -1497,6 +1496,60 @@ void verify_subject_and_serial(const Certificate& certificate, //
verify_subject(cert.get(), subject, self_signed);
}
void verify_root_of_trust(const vector<uint8_t>& verified_boot_key, bool device_locked,
VerifiedBoot verified_boot_state,
const vector<uint8_t>& verified_boot_hash) {
char property_value[PROPERTY_VALUE_MAX] = {};
if (avb_verification_enabled()) {
EXPECT_NE(property_get("ro.boot.vbmeta.digest", property_value, ""), 0);
string prop_string(property_value);
EXPECT_EQ(prop_string.size(), 64);
EXPECT_EQ(prop_string, bin2hex(verified_boot_hash));
EXPECT_NE(property_get("ro.boot.vbmeta.device_state", property_value, ""), 0);
if (!strcmp(property_value, "unlocked")) {
EXPECT_FALSE(device_locked);
} else {
EXPECT_TRUE(device_locked);
}
// Check that the device is locked if not debuggable, e.g., user build
// images in CTS. For VTS, debuggable images are used to allow adb root
// and the device is unlocked.
if (!property_get_bool("ro.debuggable", false)) {
EXPECT_TRUE(device_locked);
} else {
EXPECT_FALSE(device_locked);
}
}
// Verified boot key should be all 0's if the boot state is not verified or self signed
std::string empty_boot_key(32, '\0');
std::string verified_boot_key_str((const char*)verified_boot_key.data(),
verified_boot_key.size());
EXPECT_NE(property_get("ro.boot.verifiedbootstate", property_value, ""), 0);
if (!strcmp(property_value, "green")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::VERIFIED);
EXPECT_NE(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
} else if (!strcmp(property_value, "yellow")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::SELF_SIGNED);
EXPECT_NE(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
} else if (!strcmp(property_value, "orange")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::UNVERIFIED);
EXPECT_EQ(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
} else if (!strcmp(property_value, "red")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::FAILED);
} else {
EXPECT_EQ(verified_boot_state, VerifiedBoot::UNVERIFIED);
EXPECT_EQ(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
}
}
bool verify_attestation_record(int32_t aidl_version, //
const string& challenge, //
const string& app_id, //
@ -1551,8 +1604,6 @@ bool verify_attestation_record(int32_t aidl_version, //
EXPECT_EQ(security_level, att_keymint_security_level);
EXPECT_EQ(security_level, att_attestation_security_level);
char property_value[PROPERTY_VALUE_MAX] = {};
// TODO(b/136282179): When running under VTS-on-GSI the TEE-backed
// keymint implementation will report YYYYMM dates instead of YYYYMMDD
// for the BOOT_PATCH_LEVEL.
@ -1612,54 +1663,7 @@ bool verify_attestation_record(int32_t aidl_version, //
error = parse_root_of_trust(attest_rec->data, attest_rec->length, &verified_boot_key,
&verified_boot_state, &device_locked, &verified_boot_hash);
EXPECT_EQ(ErrorCode::OK, error);
if (avb_verification_enabled()) {
EXPECT_NE(property_get("ro.boot.vbmeta.digest", property_value, ""), 0);
string prop_string(property_value);
EXPECT_EQ(prop_string.size(), 64);
EXPECT_EQ(prop_string, bin2hex(verified_boot_hash));
EXPECT_NE(property_get("ro.boot.vbmeta.device_state", property_value, ""), 0);
if (!strcmp(property_value, "unlocked")) {
EXPECT_FALSE(device_locked);
} else {
EXPECT_TRUE(device_locked);
}
// Check that the device is locked if not debuggable, e.g., user build
// images in CTS. For VTS, debuggable images are used to allow adb root
// and the device is unlocked.
if (!property_get_bool("ro.debuggable", false)) {
EXPECT_TRUE(device_locked);
} else {
EXPECT_FALSE(device_locked);
}
}
// Verified boot key should be all 0's if the boot state is not verified or self signed
std::string empty_boot_key(32, '\0');
std::string verified_boot_key_str((const char*)verified_boot_key.data(),
verified_boot_key.size());
EXPECT_NE(property_get("ro.boot.verifiedbootstate", property_value, ""), 0);
if (!strcmp(property_value, "green")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::VERIFIED);
EXPECT_NE(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
} else if (!strcmp(property_value, "yellow")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::SELF_SIGNED);
EXPECT_NE(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
} else if (!strcmp(property_value, "orange")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::UNVERIFIED);
EXPECT_EQ(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
} else if (!strcmp(property_value, "red")) {
EXPECT_EQ(verified_boot_state, VerifiedBoot::FAILED);
} else {
EXPECT_EQ(verified_boot_state, VerifiedBoot::UNVERIFIED);
EXPECT_EQ(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
}
verify_root_of_trust(verified_boot_key, device_locked, verified_boot_state, verified_boot_hash);
att_sw_enforced.Sort();
expected_sw_enforced.Sort();

6
security/keymint/aidl/vts/functional/KeyMintAidlTestBase.h
View file

@ -31,6 +31,7 @@
#include <aidl/android/hardware/security/keymint/IKeyMintDevice.h>
#include <aidl/android/hardware/security/keymint/MacedPublicKey.h>
#include <keymint_support/attestation_record.h>
#include <keymint_support/authorization_set.h>
#include <keymint_support/openssl_utils.h>
@ -363,7 +364,10 @@ void verify_serial(X509* cert, const uint64_t expected_serial);
void verify_subject_and_serial(const Certificate& certificate, //
const uint64_t expected_serial, //
const string& subject, bool self_signed);
void verify_root_of_trust(const vector<uint8_t>& verified_boot_key, //
bool device_locked, //
VerifiedBoot verified_boot_state, //
const vector<uint8_t>& verified_boot_hash);
bool verify_attestation_record(int aidl_version, //
const string& challenge, //
const string& app_id, //

99
security/keymint/aidl/vts/functional/SecureElementProvisioningTest.cpp
View file

@ -36,6 +36,8 @@ using std::map;
using std::shared_ptr;
using std::vector;
constexpr int kRoTVersion1 = 40001;
class SecureElementProvisioningTest : public testing::Test {
protected:
static void SetUpTestSuite() {
@ -57,6 +59,83 @@ class SecureElementProvisioningTest : public testing::Test {
}
}
void validateMacedRootOfTrust(const vector<uint8_t>& rootOfTrust) {
SCOPED_TRACE(testing::Message() << "RoT: " << bin2hex(rootOfTrust));
const auto [macItem, macEndPos, macErrMsg] = cppbor::parse(rootOfTrust);
ASSERT_TRUE(macItem) << "Root of trust parsing failed: " << macErrMsg;
ASSERT_EQ(macItem->semanticTagCount(), 1);
ASSERT_EQ(macItem->semanticTag(0), cppcose::kCoseMac0SemanticTag);
ASSERT_TRUE(macItem->asArray());
ASSERT_EQ(macItem->asArray()->size(), cppcose::kCoseMac0EntryCount);
const auto& protectedItem = macItem->asArray()->get(cppcose::kCoseMac0ProtectedParams);
ASSERT_TRUE(protectedItem);
ASSERT_TRUE(protectedItem->asBstr());
const auto [protMap, protEndPos, protErrMsg] = cppbor::parse(protectedItem->asBstr());
ASSERT_TRUE(protMap);
ASSERT_TRUE(protMap->asMap());
ASSERT_EQ(protMap->asMap()->size(), 1);
const auto& algorithm = protMap->asMap()->get(cppcose::ALGORITHM);
ASSERT_TRUE(algorithm);
ASSERT_TRUE(algorithm->asInt());
ASSERT_EQ(algorithm->asInt()->value(), cppcose::HMAC_256);
const auto& unprotItem = macItem->asArray()->get(cppcose::kCoseMac0UnprotectedParams);
ASSERT_TRUE(unprotItem);
ASSERT_TRUE(unprotItem->asMap());
ASSERT_EQ(unprotItem->asMap()->size(), 0);
const auto& payload = macItem->asArray()->get(cppcose::kCoseMac0Payload);
ASSERT_TRUE(payload);
ASSERT_TRUE(payload->asBstr());
validateRootOfTrust(payload->asBstr()->value());
const auto& tag = macItem->asArray()->get(cppcose::kCoseMac0Tag);
ASSERT_TRUE(tag);
ASSERT_TRUE(tag->asBstr());
ASSERT_EQ(tag->asBstr()->value().size(), 32);
// Cannot validate tag correctness. Only the secure side has the necessary key.
}
void validateRootOfTrust(const vector<uint8_t>& payload) {
SCOPED_TRACE(testing::Message() << "RoT payload: " << bin2hex(payload));
const auto [rot, rotPos, rotErrMsg] = cppbor::parse(payload);
ASSERT_TRUE(rot);
ASSERT_EQ(rot->semanticTagCount(), 1);
ASSERT_EQ(rot->semanticTag(), kRoTVersion1);
ASSERT_TRUE(rot->asArray());
ASSERT_EQ(rot->asArray()->size(), 5);
size_t pos = 0;
const auto& vbKey = rot->asArray()->get(pos++);
ASSERT_TRUE(vbKey);
ASSERT_TRUE(vbKey->asBstr());
const auto& deviceLocked = rot->asArray()->get(pos++);
ASSERT_TRUE(deviceLocked);
ASSERT_TRUE(deviceLocked->asBool());
const auto& verifiedBootState = rot->asArray()->get(pos++);
ASSERT_TRUE(verifiedBootState);
ASSERT_TRUE(verifiedBootState->asInt());
const auto& verifiedBootHash = rot->asArray()->get(pos++);
ASSERT_TRUE(verifiedBootHash);
ASSERT_TRUE(verifiedBootHash->asBstr());
const auto& bootPatchLevel = rot->asArray()->get(pos++);
ASSERT_TRUE(bootPatchLevel);
ASSERT_TRUE(bootPatchLevel->asInt());
verify_root_of_trust(vbKey->asBstr()->value(), deviceLocked->asBool()->value(),
static_cast<VerifiedBoot>(verifiedBootState->asInt()->value()),
verifiedBootHash->asBstr()->value());
}
int32_t AidlVersion(shared_ptr<IKeyMintDevice> keymint) {
int32_t version = 0;
auto status = keymint->getInterfaceVersion(&version);
@ -96,29 +175,19 @@ TEST_F(SecureElementProvisioningTest, TeeOnly) {
vector<uint8_t> rootOfTrust1;
Status result = tee->getRootOfTrust(challenge1, &rootOfTrust1);
// TODO: Remove the next line to require TEEs to succeed.
if (!result.isOk()) return;
ASSERT_TRUE(result.isOk());
// TODO: Parse and validate rootOfTrust1 here
ASSERT_TRUE(result.isOk()) << "getRootOfTrust returned " << result.getServiceSpecificError();
validateMacedRootOfTrust(rootOfTrust1);
vector<uint8_t> rootOfTrust2;
result = tee->getRootOfTrust(challenge2, &rootOfTrust2);
ASSERT_TRUE(result.isOk());
// TODO: Parse and validate rootOfTrust2 here
validateMacedRootOfTrust(rootOfTrust2);
ASSERT_NE(rootOfTrust1, rootOfTrust2);
vector<uint8_t> rootOfTrust3;
result = tee->getRootOfTrust(challenge1, &rootOfTrust3);
ASSERT_TRUE(result.isOk());
ASSERT_EQ(rootOfTrust1, rootOfTrust3);
// TODO: Parse and validate rootOfTrust3 here
}
TEST_F(SecureElementProvisioningTest, TeeDoesNotImplementStrongBoxMethods) {
@ -252,7 +321,7 @@ TEST_F(SecureElementProvisioningTest, ProvisioningTest) {
result = tee->getRootOfTrust(challenge, &rootOfTrust);
ASSERT_TRUE(result.isOk());
// TODO: Verify COSE_Mac0 structure and content here.
validateMacedRootOfTrust(rootOfTrust);
result = sb->sendRootOfTrust(rootOfTrust);
ASSERT_TRUE(result.isOk());
@ -296,6 +365,8 @@ TEST_F(SecureElementProvisioningTest, InvalidProvisioningTest) {
result = tee->getRootOfTrust(challenge, &rootOfTrust);
ASSERT_TRUE(result.isOk());
validateMacedRootOfTrust(rootOfTrust);
vector<uint8_t> corruptedRootOfTrust = rootOfTrust;
corruptedRootOfTrust[corruptedRootOfTrust.size() / 2]++;
result = sb->sendRootOfTrust(corruptedRootOfTrust);