unit-test/keystore: simplify by removing granular mocking

cmocka mocking is a big pain. If you modify unit tests, it is very
hard to track down where and how the mocking has to be modified. The
unit test nearly becomes the implementation itself.

We can simplify and not mock all of this. The quality of the unit
tests is not impacted, as the mock_securechip.c already does KDF on
mock slot values and the resulting seed is checked, so if the
keystore.c implementation changes (e.g. using different KDF slots or
number of rounds or different hmac keys/values), the unit test will
fail.

Author: benma

test/unit-test/CMakeLists.txt

@@ -210,7 +210,7 @@ set(TEST_LIST
    cleanup
    "-Wl,--wrap=util_cleanup_32"
    keystore
-   "-Wl,--wrap=secp256k1_anti_exfil_sign,--wrap=memory_is_initialized,--wrap=memory_is_seeded,--wrap=memory_get_failed_unlock_attempts,--wrap=memory_reset_failed_unlock_attempts,--wrap=memory_increment_failed_unlock_attempts,--wrap=memory_set_encrypted_seed_and_hmac,--wrap=memory_get_encrypted_seed_and_hmac,--wrap=memory_get_salt_root,--wrap=reset_reset,--wrap=salt_hash_data,--wrap=cipher_aes_hmac_encrypt,--wrap=random_32_bytes,--wrap=securechip_kdf"
+   "-Wl,--wrap=secp256k1_anti_exfil_sign,--wrap=memory_is_initialized,--wrap=memory_is_seeded,--wrap=memory_get_failed_unlock_attempts,--wrap=memory_reset_failed_unlock_attempts,--wrap=memory_increment_failed_unlock_attempts,--wrap=memory_set_encrypted_seed_and_hmac,--wrap=memory_get_encrypted_seed_and_hmac,--wrap=memory_get_salt_root,--wrap=reset_reset,--wrap=random_32_bytes"
    keystore_antiklepto
    ""
    keystore_functional

test/unit-test/test_keystore.c

@@ -35,13 +35,6 @@
 
 #define PASSWORD ("password")
 
-int __real_securechip_kdf(securechip_slot_t slot, const uint8_t* msg, size_t len, uint8_t* kdf_out);
-int __wrap_securechip_kdf(securechip_slot_t slot, const uint8_t* msg, size_t len, uint8_t* kdf_out)
-{
-    check_expected(slot);
-    return __real_securechip_kdf(slot, msg, len, kdf_out);
-}
-
 static uint8_t _salt_root[KEYSTORE_MAX_SEED_LENGTH] = {
     0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x33, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44,
     0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22,
@@ -112,41 +105,6 @@ int __wrap_secp256k1_anti_exfil_sign(
     return __real_secp256k1_anti_exfil_sign(ctx, sig, msg32, seckey, host_data32, recid);
 }
 
-bool __real_salt_hash_data(
-    const uint8_t* data,
-    size_t data_len,
-    const char* purpose,
-    uint8_t* hash_out);
-bool __wrap_salt_hash_data(
-    const uint8_t* data,
-    size_t data_len,
-    const char* purpose,
-    uint8_t* hash_out)
-{
-    check_expected(data);
-    check_expected(data_len);
-    check_expected(purpose);
-    return __real_salt_hash_data(data, data_len, purpose, hash_out);
-}
-
-bool __real_cipher_aes_hmac_encrypt(
-    const unsigned char* in,
-    int in_len,
-    uint8_t* out,
-    int* out_len,
-    const uint8_t* secret);
-
-bool __wrap_cipher_aes_hmac_encrypt(
-    const unsigned char* in,
-    int in_len,
-    uint8_t* out,
-    int* out_len,
-    const uint8_t* secret)
-{
-    check_expected(secret);
-    return __real_cipher_aes_hmac_encrypt(in, in_len, out, out_len, secret);
-}
-
 /** Reset the SmartEEPROM configuration. */
 static void _smarteeprom_reset(void)
 {
@@ -298,35 +256,10 @@ static void _test_keystore_secp256k1_sign(void** state)
         assert_true(_pubkeys_equal(ctx, &recovered_pubkey, &expected_pubkey));
     }
 }
-
-static void _expect_stretch(const char* password)
-{
-    expect_memory(__wrap_salt_hash_data, data, password, strlen(password));
-    expect_value(__wrap_salt_hash_data, data_len, strlen(password));
-    expect_string(__wrap_salt_hash_data, purpose, "keystore_seed_access_in");
-
-    // KDF 1
-    expect_value(__wrap_securechip_kdf, slot, SECURECHIP_SLOT_ROLLKEY);
-
-    // KDF 2
-    expect_value(__wrap_securechip_kdf, slot, SECURECHIP_SLOT_KDF);
-
-    // KDF 3
-    expect_value(__wrap_securechip_kdf, slot, SECURECHIP_SLOT_KDF);
-
-    expect_memory(__wrap_salt_hash_data, data, password, strlen(password));
-    expect_value(__wrap_salt_hash_data, data_len, strlen(password));
-    expect_string(__wrap_salt_hash_data, purpose, "keystore_seed_access_out");
-}
-
 static void _expect_encrypt_and_store_seed(void)
 {
     will_return(__wrap_memory_is_initialized, false);
 
-    _expect_stretch(PASSWORD); // first stretch to encrypt
-    _expect_stretch(PASSWORD); // second stretch to verify
-
-    expect_memory(__wrap_cipher_aes_hmac_encrypt, secret, _expected_secret, 32);
     // For the AES IV:
     will_return(__wrap_random_32_bytes, _aes_iv);
 }
@@ -349,15 +282,13 @@ static void _test_keystore_create_and_unlock_twice(void** state)
     _smarteeprom_reset();
 
     will_return(__wrap_memory_is_seeded, true);
-    _expect_stretch(PASSWORD);
     assert_int_equal(KEYSTORE_OK, keystore_unlock(PASSWORD, &remaining_attempts, NULL));
 
     // Create new (different) seed.
     _expect_encrypt_and_store_seed();
     assert_int_equal(keystore_encrypt_and_store_seed(_mock_seed_2, 32, PASSWORD), KEYSTORE_OK);
 
     will_return(__wrap_memory_is_seeded, true);
-    _expect_stretch(PASSWORD);
     assert_int_equal(KEYSTORE_OK, keystore_unlock(PASSWORD, &remaining_attempts, NULL));
 }
 
@@ -375,7 +306,6 @@ static void _perform_some_unlocks(void)
     for (int i = 0; i < 3; i++) {
         _reset_reset_called = false;
         will_return(__wrap_memory_is_seeded, true);
-        _expect_stretch(PASSWORD);
         assert_int_equal(KEYSTORE_OK, keystore_unlock(PASSWORD, &remaining_attempts, NULL));
         assert_int_equal(remaining_attempts, MAX_UNLOCK_ATTEMPTS);
         assert_false(_reset_reset_called);
@@ -402,7 +332,6 @@ static void _test_keystore_unlock(void** state)
     for (int i = 1; i <= MAX_UNLOCK_ATTEMPTS; i++) {
         _reset_reset_called = false;
         will_return(__wrap_memory_is_seeded, true);
-        _expect_stretch("invalid password");
         assert_int_equal(
             i >= MAX_UNLOCK_ATTEMPTS ? KEYSTORE_ERR_MAX_ATTEMPTS_EXCEEDED
                                      : KEYSTORE_ERR_INCORRECT_PASSWORD,
@@ -483,9 +412,6 @@ static void _test_keystore_create_and_store_seed(void** state)
         size_t seed_len = test_sizes[i];
         // Seed random is xored with host entropy and the salted/hashed user password.
         will_return(__wrap_random_32_bytes, seed_random);
-        expect_memory(__wrap_salt_hash_data, data, PASSWORD, strlen(PASSWORD));
-        expect_value(__wrap_salt_hash_data, data_len, strlen(PASSWORD));
-        expect_string(__wrap_salt_hash_data, purpose, "keystore_seed_generation");
         _expect_encrypt_and_store_seed();
         assert_int_equal(
             keystore_create_and_store_seed(PASSWORD, host_entropy, seed_len), KEYSTORE_OK);