openairinterface5g/openair2/LAYER2/PDCP_v10.1.0/pdcp_security.c

/*******************************************************************************

  Eurecom OpenAirInterface
  Copyright(c) 1999 - 2013 Eurecom

  This program is free software; you can redistribute it and/or modify it
  under the terms and conditions of the GNU General Public License,
  version 2, as published by the Free Software Foundation.

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  the file called "COPYING".

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*******************************************************************************/
/*! \file pdcp_security.c
 * \brief PDCP Security Methods
 * \author ROUX Sebastien
 * \date 2013
 */
#include <stdint.h>

#include "assertions.h"

#include "UTIL/LOG/log.h"
#include "UTIL/OSA/osa_defs.h"

#include "LAYER2/MAC/extern.h"

#include "pdcp.h"
#include "pdcp_primitives.h"

#if defined(ENABLE_SECURITY)

static
u32 pdcp_get_next_count_tx(pdcp_t *pdcp_entity, u8 pdcp_header_len, u16 pdcp_sn);
static
u32 pdcp_get_next_count_rx(pdcp_t *pdcp_entity, u8 pdcp_header_len, u16 pdcp_sn);

static
u32 pdcp_get_next_count_tx(pdcp_t *pdcp_entity, u8 pdcp_header_len, u16 pdcp_sn)
{
    u32 count;
    /* For TX COUNT = TX_HFN << length of SN | pdcp SN */
    if (pdcp_header_len == PDCP_CONTROL_PLANE_DATA_PDU_SN_SIZE) {
        /* 5 bits length SN */
        count = (pdcp_entity->tx_hfn << 5)  | (pdcp_sn & 0x001F);
    } else {
        /* 12 bits length SN */
        count = (pdcp_entity->tx_hfn << 12) | (pdcp_sn & 0x0FFF);
    }
//     LOG_D(PDCP, "[OSA] TX COUNT = 0x%08x\n", count);

    return count;
}

static
u32 pdcp_get_next_count_rx(pdcp_t *pdcp_entity, u8 pdcp_header_len, u16 pdcp_sn)
{
    u32 count;
    /* For RX COUNT = RX_HFN << length of SN | pdcp SN of received PDU */
    if (pdcp_header_len == PDCP_CONTROL_PLANE_DATA_PDU_SN_SIZE) {
        /* 5 bits length SN */
        count = (pdcp_entity->rx_hfn << 5)  | (pdcp_sn & 0x001F);
    } else {
        /* 12 bits length SN */
        count = (pdcp_entity->rx_hfn << 12) | (pdcp_sn & 0x0FFF);
    }
//     LOG_D(PDCP, "[OSA] RX COUNT = 0x%08x\n", count);

    return count;
}

int pdcp_apply_security(pdcp_t *pdcp_entity, rb_id_t rb_id,
                        u8 pdcp_header_len, u16 current_sn, u8 *pdcp_pdu_buffer,
                        u16 sdu_buffer_size)
{
    u8 *buffer_encrypted = NULL;
    stream_cipher_t encrypt_params;

    DevAssert(pdcp_entity != NULL);
    DevAssert(pdcp_pdu_buffer != NULL);
    DevCheck(rb_id < NB_RB_MAX && rb_id >= 0, rb_id, NB_RB_MAX, 0);

    encrypt_params.direction  = (pdcp_entity->is_ue == 1) ? SECU_DIRECTION_UPLINK : SECU_DIRECTION_DOWNLINK;
    encrypt_params.bearer     = rb_id;
    encrypt_params.count      = pdcp_get_next_count_tx(pdcp_entity, pdcp_header_len, current_sn);
    encrypt_params.key_length = 16;

    if (rb_id < DTCH) {
        /* SRBs */
        u8 *mac_i;

        LOG_D(PDCP, "[OSA][RB %d] %s Applying control-plane security\n",
              rb_id, (pdcp_entity->is_ue != 0) ? "UE -> eNB" : "eNB -> UE");

        encrypt_params.message    = pdcp_pdu_buffer;
        encrypt_params.blength    = (pdcp_header_len + sdu_buffer_size) << 3;
        encrypt_params.key        = pdcp_entity->kRRCint;

        mac_i = &pdcp_pdu_buffer[pdcp_header_len + sdu_buffer_size];

        /* Both header and data parts are integrity protected for
         * control-plane PDUs */
        stream_compute_integrity(pdcp_entity->integrityProtAlgorithm, &encrypt_params,
                                 mac_i);

        encrypt_params.key = pdcp_entity->kRRCenc;
    } else {
        LOG_D(PDCP, "[OSA][RB %d] %s Applying user-plane security\n",
              rb_id, (pdcp_entity->is_ue != 0) ? "UE -> eNB" : "eNB -> UE");

        encrypt_params.key = pdcp_entity->kUPenc;
    }

    encrypt_params.message    = &pdcp_pdu_buffer[pdcp_header_len];
    encrypt_params.blength    = sdu_buffer_size << 3;

    buffer_encrypted = &pdcp_pdu_buffer[pdcp_header_len];

    /* Apply ciphering if any requested */
    stream_encrypt(pdcp_entity->cipheringAlgorithm, &encrypt_params,
                   &buffer_encrypted);

    return 0;
}

int pdcp_validate_security(pdcp_t *pdcp_entity, rb_id_t rb_id,
                           u8 pdcp_header_len, u16 current_sn, u8 *pdcp_pdu_buffer,
                           u16 sdu_buffer_size)
{
    u8 *buffer_decrypted = NULL;
    stream_cipher_t decrypt_params;

    DevAssert(pdcp_entity != NULL);

    DevAssert(pdcp_pdu_buffer != NULL);
    DevCheck(rb_id < NB_RB_MAX && rb_id >= 0, rb_id, NB_RB_MAX, 0);

    buffer_decrypted = (u8*)&pdcp_pdu_buffer[pdcp_header_len];

    decrypt_params.direction  = (pdcp_entity->is_ue == 1) ? SECU_DIRECTION_DOWNLINK : SECU_DIRECTION_UPLINK ;
    decrypt_params.bearer     = rb_id;
    decrypt_params.count      = pdcp_get_next_count_rx(pdcp_entity, pdcp_header_len, current_sn);
    decrypt_params.message    = &pdcp_pdu_buffer[pdcp_header_len];
    decrypt_params.blength    = (sdu_buffer_size - pdcp_header_len) << 3;
    decrypt_params.key_length = 16;

    if (rb_id < DTCH) {
        LOG_D(PDCP, "[OSA][RB %d] %s Validating control-plane security\n",
              rb_id, (pdcp_entity->is_ue != 0) ? "eNB -> UE" : "UE -> eNB");
        decrypt_params.key = pdcp_entity->kRRCenc;
    } else {
        LOG_D(PDCP, "[OSA][RB %d] %s Validating user-plane security\n",
              rb_id, (pdcp_entity->is_ue != 0) ? "eNB -> UE" : "UE -> eNB");
        decrypt_params.key = pdcp_entity->kUPenc;
    }

    /* Uncipher the block */
    stream_decrypt(pdcp_entity->cipheringAlgorithm, &decrypt_params, &buffer_decrypted);

    if (rb_id < DTCH) {
        /* Now check the integrity of the complete PDU */
        decrypt_params.message    = pdcp_pdu_buffer;
        decrypt_params.blength    = sdu_buffer_size << 3;
        decrypt_params.key        = pdcp_entity->kRRCint;

        if (stream_check_integrity(pdcp_entity->integrityProtAlgorithm,
            &decrypt_params, &pdcp_pdu_buffer[sdu_buffer_size]) != 0) {
            LOG_E(PDCP, "[OSA] failed to validate MAC-I of incoming PDU\n");
            return -1;
        }
    }
    return 0;
}

#endif /* ENABLE_SECURITY */