optee km4.0 VTS: PerInstance/AttestationTest.RsaAttestation/0_default failed
./VtsHalKeymasterV4_0TargetTest --gtest_filter=PerInstance/AttestationTest.RsaAttestation/0_default
异常1：
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:364: Failure
Expected equality of these values:
ErrorCode::OK
Which is: OK
error
Which is: UNKNOWN_ERROR
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:4305: Failure
Value of: verify_attestation_record("challenge", "foo", key_characteristics_.softwareEnforced, key_characteristics_.hardwareEnforced, SecLevel(), cert_chain[0])
Actual: false
Expected: true
[ FAILED ] PerInstance/AttestationTest.RsaAttestation/0_default, where GetParam() = "default" (17408 ms)
[----------] 1 test from PerInstance/AttestationTest (17408 ms total)
[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (17410 ms total)
[ PASSED ] 0 tests.
[ FAILED ] 1 test, listed below:
[ FAILED ] PerInstance/AttestationTest.RsaAttestation/0_default, where GetParam() = "default"
1 FAILED TEST
代码排查：
bool verify_attestation_record(const string& challenge, const string& app_id, AuthorizationSet expected_sw_enforced, AuthorizationSet expected_hw_enforced, SecurityLevel security_level, const hidl_vec<uint8_t>& attestation_cert) { X509_Ptr cert(parse_cert_blob(attestation_cert)); EXPECT_TRUE(!!cert.get()); if (!cert.get()) return false; ASN1_OCTET_STRING* attest_rec = get_attestation_record(cert.get()); EXPECT_TRUE(!!attest_rec); if (!attest_rec) return false; AuthorizationSet att_sw_enforced; AuthorizationSet att_hw_enforced; uint32_t att_attestation_version; uint32_t att_keymaster_version; SecurityLevel att_attestation_security_level; SecurityLevel att_keymaster_security_level; HidlBuf att_challenge; HidlBuf att_unique_id; HidlBuf att_app_id; ALOGD("1. verify_attestation_record ==> parse_attestation_record"); auto error = parse_attestation_record(attest_rec->data, // attest_rec->length, // &att_attestation_version, // &att_attestation_security_level, // &att_keymaster_version, // &att_keymaster_security_level, // &att_challenge, // &att_sw_enforced, // &att_hw_enforced, // &att_unique_id); EXPECT_EQ(ErrorCode::OK, error); if (error != ErrorCode::OK) { ALOGE("parse_attestation_record failed error: %d", error); return false; } EXPECT_GE(att_attestation_version, 3U); //以下省略 }
通过增加log，发现异常点在d2i_KM_KEY_DESCRIPTION，log如下：
13039 02-06 07:15:54.187 3140 3140 D keymaster_hidl_hal_test: 3. RsaAttestation ==> verify_attestation_record
13040 02-06 07:15:54.240 3140 3140 D keymaster_hidl_hal_test: 1. verify_attestation_record ==> parse_attestation_record
13041 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: parse_attestation_record enter
13042 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: ==dump asn1_key_desc start, size = 171
13043 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: dumpData data_len : 171
13044 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [000] 30 81 a8 02 01 02 0a 01 01 02 01 03 0a 01 01 04
13045 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [001] 09 63 68 61 6c 6c 65 6e 67 65 04 00 30 12 bf 85
13046 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [002] 3d 05 02 03 02 28 e2 bf 85 45 05 04 03 66 6f 6f
13047 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [003] 30 79 a1 08 31 06 02 01 02 02 01 03 a2 03 02 01
13048 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [004] 01 a3 04 02 02 08 00 a5 05 31 03 02 01 04 a6 05
13049 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [005] 31 03 02 01 05 bf 81 48 05 02 03 01 00 01 bf 83
13050 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [006] 77 02 05 00 bf 85 3e 03 02 01 00 bf 85 40 2a 30
13051 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [007] 28 04 20 c2 94 47 2a b9 ee f2 c2 bc 4c 85 33 a3
13052 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [008] 20 d6 21 11 af d4 44 57 f0 af 96 0f eb a8 92 86
13053 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [009] f3 9d e4 01 01 ff 0a 01 00 bf 85 41 05 02 03 01
13054 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: [00a] ad b0 bf 85 42 05 02 03 03 15 de
13055 02-06 07:15:54.240 3140 3140 D keymaster_4_attestation_record_cpp: ==dump asn1_key_desc end, size = 171
13056 02-06 07:15:54.260 3140 3140 E keymaster_4_attestation_record_cpp: d2i_KM_KEY_DESCRIPTION failed, return -1000
13057 02-06 07:15:54.261 3140 3140 E keymaster_hidl_hal_test: parse_attestation_record failed error: -1000
相关代码：
ErrorCode parse_attestation_record(const uint8_t* asn1_key_desc, size_t asn1_key_desc_len,
uint32_t* attestation_version, //
SecurityLevel* attestation_security_level,
uint32_t* keymaster_version,
SecurityLevel* keymaster_security_level,
hidl_vec<uint8_t>* attestation_challenge,
AuthorizationSet* software_enforced,
AuthorizationSet* tee_enforced, //
hidl_vec<uint8_t>* unique_id) {
ALOGD("parse_attestation_record enter");
ALOGD("==dump asn1_key_desc start, size = %zu", asn1_key_desc_len);
atts_dump((uint8_t*)asn1_key_desc, (uint32_t)asn1_key_desc_len);
ALOGD("==dump asn1_key_desc end, size = %zu", asn1_key_desc_len);
const uint8_t* p = asn1_key_desc;
KM_KEY_DESCRIPTION_Ptr record(d2i_KM_KEY_DESCRIPTION(nullptr, &p, asn1_key_desc_len));
if (!record.get()) {
ALOGE("d2i_KM_KEY_DESCRIPTION failed, return -1000");
return ErrorCode::UNKNOWN_ERROR;
}
//省略若干
return extract_auth_list(record->tee_enforced, tee_enforced);
}
从log中可以看到，我们已经打印出asn1_key_desc的值，将该值在http://lapo.it/asn1js/ 中进行ASN.1的解析，同时在boringssl中增加log打印（printf打印，编译出来的VTS程序在执行时，相关打印会在console中输出）。
结合IKeymasterDevice.hal中KeyDescription的定义，再将以上解析和log进行对比，能看出key description的异常在RootOfTrust中：
数据：
30 81 a8 02 01 02 0a 01 01 02 01 03 0a 01 01 04 09 63 68 61 6c 6c 65 6e 67 65 04 00 30 12 bf 85 3d 05 02 03 10 5e 37 bf 85 45 05 04 03 66 6f 6f 30 79 a1 08 31 06 02 01 02 02 01 03 a2 03 02 01 01 a3 04 02 02 08 00 a5 05 31 03 02 01 04 a6 05 31 03 02 01 05 bf 81 48 05 02 03 01 00 01 bf 83 77 02 05 00 bf 85 3e 03 02 01 00 bf 85 40 2a 30 28 04 20 c9 a1 7d 3a a3 7b 40 ba 46 ba 86 31 f9 3b 8d 87 ce 05 4c f7 74 91 1b b0 ca 3c bd 77 ae da 27 fc 01 01 ff 0a 01 00 bf 85 41 05 02 03 01 ad b0 bf 85 42 05 02 03 03 15 de
解析异常点：
* RootOfTrust ::= SEQUENCE {
* verifiedBootKey OCTET_STRING,
* deviceLocked BOOLEAN,
* verifiedBootState VerifiedBootState,
* # verifiedBootHash must contain 32-byte value that represents the state of all binaries
* # or other components validated by verified boot. Updating any verified binary or
* # component must cause this value to change.
* verifiedBootHash OCTET_STRING,
* }
可见ROT中存在4个分量，但实际解析出来的只有3个，缺了一个OCTET_STRING。
封装ROT信息部分在TA中实现如下：
/**
* \brief Writes RootOfTrust to a buffer
*
* \note This function works backwards in data buffer.
*
* \param p Pointer to the array to be populated. If no memory allocated
* - allocation will be processed inside this routine.
* \param len Length of resulting array.
*
* \return 0 on success, -1 on failure.
*/
static int asn1_write_rot (uint8_t verified_boot, unsigned char **p,
size_t *len) {
int len_ret = 0, ret;
unsigned char buf[ASN1_BUF_LEN_DEFAULT];
unsigned char *ptr = buf + sizeof(buf);
unsigned char *start = buf;
TEE_Result res = TEE_SUCCESS;
//get root of device data from libhandlerot library
root_of_trust_info_t device_rot;
memset(&device_rot, 0, sizeof(root_of_trust_info_t));
res = get_device_rot(&device_rot);
DMSG("get_device_rot result:%d \n", res);
int lock_state = device_rot.devcelock_state;
MBEDTLS_ASN1_CHK_ADD(len_ret, mbedtls_asn1_write_enum(&ptr, start,
verified_boot));
MBEDTLS_ASN1_CHK_ADD(len_ret, mbedtls_asn1_write_bool(&ptr, start,
lock_state));
MBEDTLS_ASN1_CHK_ADD(len_ret, mbedtls_asn1_write_octet_string(&ptr, start,
device_rot.vbmeta_digest,
sizeof(device_rot.vbmeta_digest)));
MBEDTLS_ASN1_CHK_ADD(len_ret, mbedtls_asn1_write_len(&ptr, start,
(size_t)len_ret));
MBEDTLS_ASN1_CHK_ADD(len_ret,
mbedtls_asn1_write_tag(&ptr, start,
MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE));
if (!*p) {
*p = TEE_Malloc((uint32_t)len_ret, TEE_MALLOC_FILL_ZERO);
}
if (!*p) {
EMSG ("Can not populate non-allocated buffer");
return -1;
}
TEE_MemMove(*p, ptr, (uint32_t)len_ret);
*len = (size_t)len_ret;
return 0;
}
从代码看，确实只封装了3个分量，分别是verified boot状态，lock state状态和digest数组。
根据IKeymasterDevice.hal中的定义，调整ROT的封装，先封装digest数组，接着是verified boot状态，lock状态，最后是key数组。
修改后的TA更新之后，测试结果如下：
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:454: Failure
Value of: device_locked
Actual: true
Expected: false
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:465: Failure
Value of: device_locked
Actual: true
Expected: false
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:483: Failure
Expected equality of these values:
verified_boot_state
Which is: 0
KM_VERIFIED_BOOT_UNVERIFIED
Which is: 2
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:485: Failure
Expected equality of these values:
0
memcmp(verified_boot_key.data(), empty_boot_key.data(), verified_boot_key.size())
Which is: 1
[ FAILED ] PerInstance/AttestationTest.RsaAttestation/0_default, where GetParam() = "default" (18936 ms)
[----------] 1 test from PerInstance/AttestationTest (18936 ms total)
[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (18937 ms total)
[ PASSED ] 0 tests.
[ FAILED ] 1 test, listed below:
[ FAILED ] PerInstance/AttestationTest.RsaAttestation/0_default, where GetParam() = "default"
1 FAILED TEST
异常2：
从上述测试结果来看，device_locked状态和verified_boot_state不对，对应测试代码如下
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);
}
if (!property_get_bool("ro.debuggable", false)) {
EXPECT_TRUE(device_locked);
} else {
EXPECT_FALSE(device_locked);
}
EXPECT_NE(property_get("ro.boot.verifiedbootstate", property_value, ""), 0);
if (!strcmp(property_value, "green")) {
EXPECT_EQ(verified_boot_state, KM_VERIFIED_BOOT_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, KM_VERIFIED_BOOT_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, KM_VERIFIED_BOOT_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, KM_VERIFIED_BOOT_FAILED);
} else {
EXPECT_EQ(verified_boot_state, KM_VERIFIED_BOOT_UNVERIFIED);
EXPECT_NE(0, memcmp(verified_boot_key.data(), empty_boot_key.data(),
verified_boot_key.size()));
}
设备属性值如下：
[ro.boot.vbmeta.device_state]: [unlocked]
[ro.debuggable]: [1]
[ro.boot.verifiedbootstate]: [orange]
TA中增加的log打印如下：
0818 D/TA: asn1_write_rot:1569 device_locked = 1
0823 D/TA: asn1_write_rot:1583 input verified_boot = 0, rot verified boot state = 2
TA中log说明lock值为1，封装到ROT中的verified boot值为0。这个与系统属性匹配不上，系统属性显示设备状态为unlocked，verified boot state为orange。
也就是说TA中封装错误了。
核查后，修改TA中封装的逻辑，更新TA后测试仍旧有异常。
异常3：
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:485: Failure
Expected equality of these values:
0
memcmp(verified_boot_key.data(), empty_boot_key.data(), verified_boot_key.size())
Which is: 1
[ FAILED ] PerInstance/AttestationTest.RsaAttestation/0_default, where GetParam() = "default" (18823 ms)
[----------] 1 test from PerInstance/AttestationTest (18823 ms total)
[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (18824 ms total)
[ PASSED ] 0 tests.
[ FAILED ] 1 test, listed below:
[ FAILED ] PerInstance/AttestationTest.RsaAttestation/0_default, where GetParam() = "default"
1 FAILED TEST
对应VTS代码：
else if (!strcmp(property_value, "orange")) { EXPECT_EQ(verified_boot_state, KM_VERIFIED_BOOT_UNVERIFIED); EXPECT_EQ(0, memcmp(verified_boot_key.data(), empty_boot_key.data(), verified_boot_key.size())); }
其中std::string empty_boot_key(32, '\0');
也就是说，当verified boot状态为orange时，预期verified boot key需要封装一个空串进来。
根据该判定逻辑，修改TA中对应封装代码。
更新TA后，出现如下测试异常。
异常4：
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:370: Failure
Expected: (att_attestation_version) >= (3U), actual: 2 vs 3
hardware/interfaces/keymaster/4.0/vts/functional/keymaster_hidl_hal_test.cpp:374: Failure
Expected: (att_keymaster_version) >= (4U), actual: 3 vs 4
这两行异常对应VTS代码为：
EXPECT_GE(att_attestation_version, 3U); expected_sw_enforced.push_back(TAG_ATTESTATION_APPLICATION_ID, HidlBuf(app_id)); EXPECT_GE(att_keymaster_version, 4U);
IKeymasterDevice.hal中定义：
* KeyDescription ::= SEQUENCE {
* attestationVersion INTEGER, # Value 3
* attestationSecurityLevel SecurityLevel, # See below
* keymasterVersion INTEGER, # Value 4
* keymasterSecurityLevel SecurityLevel, # See below
* attestationChallenge OCTET_STRING, # Tag::ATTESTATION_CHALLENGE from attestParams
* uniqueId OCTET_STRING, # Empty unless key has Tag::INCLUDE_UNIQUE_ID
* softwareEnforced AuthorizationList, # See below
* hardwareEnforced AuthorizationList, # See below
* }
TA中定义：
keymaster\ta\mbedtls_proxy.c
#define KEYMASTER_VERSION 3 #define ATTESTATION_VERSION 2
修改TA中定义后，测试PASS.
[ OK ] PerInstance/AttestationTest.RsaAttestation/0_default (16978 ms)
[----------] 1 test from PerInstance/AttestationTest (16978 ms total)
[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (16979 ms total)
[ PASSED ] 1 test.
总结：
耗时最久的是异常1的分析，因为boringssl中的log输出，还要分析数据具体的解析，其次获取设备rot信息，因为这部分代码是另外一个同事写的，smc调用最终在BL31中实现的，还跑去看了这部分的代码，才发现底层的实现和android这边的定义有差异。所以设备状态才反了。
