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sm: validate OOB data before sending random nonce

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This commit is contained in:
Matthias Ringwald 2024-10-30 12:19:34 +01:00
parent 25d5427a34
commit 2419120a64
1 changed files with 38 additions and 15 deletions
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53
src/ble/sm.c
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@ -1634,6 +1634,7 @@ static inline void sm_pdu_received_in_wrong_state(sm_connection_t * sm_conn){
static void sm_sc_prepare_dhkey_check(sm_connection_t * sm_conn);
static bool sm_passkey_used(stk_generation_method_t method);
static bool sm_just_works_or_numeric_comparison(stk_generation_method_t method);
static void sm_sc_generate_nx_for_send_random(sm_connection_t * sm_conn);
static void sm_sc_start_calculating_local_confirm(sm_connection_t * sm_conn){
if (setup->sm_stk_generation_method == OOB){
@ -1647,9 +1648,7 @@ static void sm_sc_state_after_receiving_random(sm_connection_t * sm_conn){
if (IS_RESPONDER(sm_conn->sm_role)){
// Responder
if (setup->sm_stk_generation_method == OOB){
// generate Nb
log_info("Generate Nb");
btstack_crypto_random_generate(&sm_crypto_random_request, setup->sm_local_nonce, 16, &sm_handle_random_result_sc_next_send_pairing_random, (void *)(uintptr_t) sm_conn->sm_handle);
sm_sc_generate_nx_for_send_random(sm_conn);
} else {
sm_conn->sm_engine_state = SM_SC_SEND_PAIRING_RANDOM;
}
@ -1709,7 +1708,12 @@ static void sm_sc_cmac_done(uint8_t * hash){
sm_pairing_error(sm_conn, SM_REASON_CONFIRM_VALUE_FAILED);
break;
}
sm_sc_state_after_receiving_random(sm_conn);
// for OOB, C is verified before generating and sending random Nonce
if (setup->sm_stk_generation_method == OOB){
sm_sc_generate_nx_for_send_random(sm_conn);
} else {
sm_sc_state_after_receiving_random(sm_conn);
}
break;
case SM_SC_W4_CALCULATE_G2: {
uint32_t vab = big_endian_read_32(hash, 12) % 1000000;
@ -2046,6 +2050,12 @@ static void sm_sc_calculate_f6_to_verify_dhkey_check(sm_connection_t * sm_conn){
}
}
static void sm_sc_generate_nx_for_send_random(sm_connection_t * sm_conn){
// generate Nx
log_info("Generate N%c", IS_RESPONDER(sm_conn->sm_role) ? 'b' : 'a');
btstack_crypto_random_generate(&sm_crypto_random_request, setup->sm_local_nonce, 16, &sm_handle_random_result_sc_next_send_pairing_random, (void*)(uintptr_t) sm_conn->sm_handle);
}
#ifdef ENABLE_CROSS_TRANSPORT_KEY_DERIVATION
//
@ -4614,9 +4624,13 @@ static void sm_pdu_handler(sm_connection_t *sm_conn, uint8_t sm_pdu_code, const
sm_sc_start_calculating_local_confirm(sm_conn);
break;
case OOB:
// generate Nx
log_info("Generate Na");
btstack_crypto_random_generate(&sm_crypto_random_request, setup->sm_local_nonce, 16, &sm_handle_random_result_sc_next_send_pairing_random, (void*)(uintptr_t) sm_conn->sm_handle);
if (setup->sm_have_oob_data){
// if we have received rb & cb, verify Cb = f4(PKb, PKb, rb, 0)
sm_conn->sm_engine_state = SM_SC_W2_CMAC_FOR_CHECK_CONFIRMATION;
} else {
// otherwise, generate our nonce
sm_sc_generate_nx_for_send_random(sm_conn);
}
break;
default:
btstack_assert(false);
@ -4684,16 +4698,16 @@ static void sm_pdu_handler(sm_connection_t *sm_conn, uint8_t sm_pdu_code, const
// setup local random, set to zero if remote did not receive our data
log_info("Received nonce, setup local random ra/rb for dhkey check");
if (IS_RESPONDER(sm_conn->sm_role)){
if (sm_pairing_packet_get_oob_data_flag(setup->sm_m_preq) == 0u){
if (IS_RESPONDER(sm_conn->sm_role)) {
if (sm_pairing_packet_get_oob_data_flag(setup->sm_m_preq) == 0u) {
log_info("Reset rb as A does not have OOB data");
memset(setup->sm_rb, 0, 16);
} else {
(void)memcpy(setup->sm_rb, sm_sc_oob_random, 16);
(void) memcpy(setup->sm_rb, sm_sc_oob_random, 16);
log_info("Use stored rb");
log_info_hexdump(setup->sm_rb, 16);
}
} else {
} else {
if (sm_pairing_packet_get_oob_data_flag(setup->sm_s_pres) == 0u){
log_info("Reset ra as B does not have OOB data");
memset(setup->sm_ra, 0, 16);
@ -4704,11 +4718,20 @@ static void sm_pdu_handler(sm_connection_t *sm_conn, uint8_t sm_pdu_code, const
}
}
// validate confirm value if Cb = f4(PKb, Pkb, rb, 0) for OOB if data received
if (setup->sm_have_oob_data){
sm_conn->sm_engine_state = SM_SC_W2_CMAC_FOR_CHECK_CONFIRMATION;
break;
if (IS_RESPONDER(sm_conn->sm_role)){
if (setup->sm_have_oob_data){
// if we have received ra & ca, verify Ca = f4(PKa, PKa, ra, 0)
sm_conn->sm_engine_state = SM_SC_W2_CMAC_FOR_CHECK_CONFIRMATION;
} else {
// otherwise, generate our nonce
sm_sc_generate_nx_for_send_random(sm_conn);
}
} else {
// Confirm value already validated if received before,
// move on to DHKey check
sm_sc_prepare_dhkey_check(sm_conn);
}
break;
}
// TODO: we only get here for Responder role with JW/NC