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srsLTE
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srsLTE/srsue/src/stack/upper/nas_base.cc

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/**
* Copyright 2013-2022 Software Radio Systems Limited
*
* This file is part of srsRAN.
*
* srsRAN is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of
* the License, or (at your option) any later version.
*
* srsRAN is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* A copy of the GNU Affero General Public License can be found in
* the LICENSE file in the top-level directory of this distribution
* and at http://www.gnu.org/licenses/.
*
*/
#include "srsue/hdr/stack/upper/nas_base.h"
using namespace srsran;
namespace srsue {
nas_base::nas_base(srslog::basic_logger& logger_, uint32_t mac_offset_, uint32_t seq_offset_, uint32_t bearer_id_) :
logger(logger_), mac_offset(mac_offset_), seq_offset(seq_offset_), bearer_id(bearer_id_)
{}
int nas_base::parse_security_algorithm_list(std::string algorithm_string, bool* algorithm_caps)
{
// parse and sanity check security algorithm list
std::vector<uint8_t> cap_list;
srsran::string_parse_list(algorithm_string, ',', cap_list);
if (cap_list.empty()) {
logger.error("Empty security list. Select at least one security algorithm.");
return SRSRAN_ERROR;
}
for (std::vector<uint8_t>::const_iterator it = cap_list.begin(); it != cap_list.end(); ++it) {
if (*it < 4) {
algorithm_caps[*it] = true;
} else {
logger.error("EEA/EIA/5G-EA/5G-IA %d is not a valid algorithm.", *it);
return SRSRAN_ERROR;
}
}
return SRSRAN_SUCCESS;
}
/*******************************************************************************
* Security
******************************************************************************/
void nas_base::integrity_generate(uint8_t* key_128,
uint32_t count,
uint8_t direction,
uint8_t* msg,
uint32_t msg_len,
uint8_t* mac)
{
switch (ctxt_base.integ_algo) {
case INTEGRITY_ALGORITHM_ID_EIA0:
break;
case INTEGRITY_ALGORITHM_ID_128_EIA1:
security_128_eia1(key_128, count, bearer_id, direction, msg, msg_len, mac);
break;
case INTEGRITY_ALGORITHM_ID_128_EIA2:
security_128_eia2(key_128, count, bearer_id, direction, msg, msg_len, mac);
break;
case INTEGRITY_ALGORITHM_ID_128_EIA3:
security_128_eia3(key_128, count, bearer_id, direction, msg, msg_len, mac);
break;
default:
break;
}
}
// This function depends to a valid k_nas_int.
// This key is generated in the security mode command.
bool nas_base::integrity_check(byte_buffer_t* pdu)
{
if (pdu == nullptr) {
logger.error("Invalid PDU");
return false;
}
if (pdu->N_bytes > seq_offset) {
uint8_t exp_mac[4] = {0};
uint8_t* mac = &pdu->msg[mac_offset];
// generate expected MAC
uint32_t count_est = (ctxt_base.rx_count & 0x00FFFF00u) | pdu->msg[seq_offset];
integrity_generate(&ctxt_base.k_nas_int[16],
count_est,
SECURITY_DIRECTION_DOWNLINK,
&pdu->msg[seq_offset],
pdu->N_bytes - seq_offset,
&exp_mac[0]);
// Check if expected mac equals the sent mac
for (int i = 0; i < 4; i++) {
if (exp_mac[i] != mac[i]) {
logger.warning("Integrity check failure. Local: count=%d, [%02x %02x %02x %02x], "
"Received: count=%d, [%02x %02x %02x %02x]",
count_est,
exp_mac[0],
exp_mac[1],
exp_mac[2],
exp_mac[3],
pdu->msg[seq_offset],
mac[0],
mac[1],
mac[2],
mac[3]);
return false;
}
}
logger.info("Integrity check ok. Local: count=%d, Received: count=%d [%02x %02x %02x %02x]",
count_est,
pdu->msg[seq_offset],
mac[0],
mac[1],
mac[2],
mac[3]);
// Updated local count (according to TS 24.301 Sec. 4.4.3.3)
if (count_est != ctxt_base.rx_count) {
logger.info("Update local count to estimated count %d", count_est);
ctxt_base.rx_count = count_est;
}
return true;
} else {
logger.error("Invalid integrity check PDU size (%d)", pdu->N_bytes);
return false;
}
}
void nas_base::cipher_encrypt(byte_buffer_t* pdu)
{
byte_buffer_t pdu_tmp;
if (ctxt_base.cipher_algo != CIPHERING_ALGORITHM_ID_EEA0) {
logger.debug("Encrypting PDU. count=%d", ctxt_base.tx_count);
}
switch (ctxt_base.cipher_algo) {
case CIPHERING_ALGORITHM_ID_EEA0:
break;
case CIPHERING_ALGORITHM_ID_128_EEA1:
security_128_eea1(&ctxt_base.k_nas_enc[16],
ctxt_base.tx_count,
bearer_id,
SECURITY_DIRECTION_UPLINK,
&pdu->msg[seq_offset + 1],
pdu->N_bytes - seq_offset + 1,
&pdu_tmp.msg[seq_offset + 1]);
memcpy(&pdu->msg[seq_offset + 1], &pdu_tmp.msg[seq_offset + 1], pdu->N_bytes - seq_offset + 1);
break;
case CIPHERING_ALGORITHM_ID_128_EEA2:
security_128_eea2(&ctxt_base.k_nas_enc[16],
ctxt_base.tx_count,
bearer_id,
SECURITY_DIRECTION_UPLINK,
&pdu->msg[seq_offset + 1],
pdu->N_bytes - seq_offset + 1,
&pdu_tmp.msg[seq_offset + 1]);
memcpy(&pdu->msg[seq_offset + 1], &pdu_tmp.msg[seq_offset + 1], pdu->N_bytes - seq_offset + 1);
break;
case CIPHERING_ALGORITHM_ID_128_EEA3:
security_128_eea3(&ctxt_base.k_nas_enc[16],
ctxt_base.tx_count,
bearer_id,
SECURITY_DIRECTION_UPLINK,
&pdu->msg[seq_offset + 1],
pdu->N_bytes - seq_offset + 1,
&pdu_tmp.msg[seq_offset + 1]);
memcpy(&pdu->msg[seq_offset + 1], &pdu_tmp.msg[seq_offset + 1], pdu->N_bytes - seq_offset + 1);
break;
default:
logger.error("Ciphering algorithm not known");
break;
}
}
void nas_base::cipher_decrypt(byte_buffer_t* pdu)
{
byte_buffer_t tmp_pdu;
uint32_t count_est = (ctxt_base.rx_count & 0x00FFFF00u) | pdu->msg[5];
if (ctxt_base.cipher_algo != CIPHERING_ALGORITHM_ID_EEA0) {
logger.debug("Decrypting PDU. Local: count=%d, Received: count=%d", ctxt_base.rx_count, count_est);
}
switch (ctxt_base.cipher_algo) {
case CIPHERING_ALGORITHM_ID_EEA0:
break;
case CIPHERING_ALGORITHM_ID_128_EEA1:
security_128_eea1(&ctxt_base.k_nas_enc[16],
count_est,
bearer_id,
SECURITY_DIRECTION_DOWNLINK,
&pdu->msg[seq_offset + 1],
pdu->N_bytes - seq_offset + 1,
&tmp_pdu.msg[seq_offset + 1]);
memcpy(&pdu->msg[seq_offset + 1], &tmp_pdu.msg[seq_offset + 1], pdu->N_bytes - seq_offset + 1);
break;
case CIPHERING_ALGORITHM_ID_128_EEA2:
security_128_eea2(&ctxt_base.k_nas_enc[16],
count_est,
bearer_id,
SECURITY_DIRECTION_DOWNLINK,
&pdu->msg[seq_offset + 1],
pdu->N_bytes - seq_offset + 1,
&tmp_pdu.msg[seq_offset + 1]);
logger.debug(tmp_pdu.msg, pdu->N_bytes, "Decrypted");
memcpy(&pdu->msg[seq_offset + 1], &tmp_pdu.msg[seq_offset + 1], pdu->N_bytes - seq_offset + 1);
break;
case CIPHERING_ALGORITHM_ID_128_EEA3:
security_128_eea3(&ctxt_base.k_nas_enc[16],
count_est,
bearer_id,
SECURITY_DIRECTION_DOWNLINK,
&pdu->msg[seq_offset + 1],
pdu->N_bytes - seq_offset + 1,
&tmp_pdu.msg[seq_offset + 1]);
logger.debug(tmp_pdu.msg, pdu->N_bytes, "Decrypted");
memcpy(&pdu->msg[seq_offset + 1], &tmp_pdu.msg[seq_offset + 1], pdu->N_bytes - seq_offset + 1);
break;
default:
logger.error("Ciphering algorithms not known");
break;
}
}
} // namespace srsue
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