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/*! \file gprs_cipher_core.c
* GPRS LLC cipher core infrastructure */
/*
* (C) 2010 by Harald Welte <laforge@gnumonks.org>
*
* All Rights Reserved
*
* SPDX-License-Identifier: GPL-2.0+
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
*/
#include "config.h"
#include <errno.h>
#include <stdint.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/plugin.h>
#include <osmocom/crypt/gprs_cipher.h>
/*! \addtogroup crypto
* @{
*/
static LLIST_HEAD(gprs_ciphers);
static struct gprs_cipher_impl *selected_ciphers[_GPRS_ALGO_NUM];
const struct value_string gprs_cipher_names[] = {
{ GPRS_ALGO_GEA0, "GEA0" },
{ GPRS_ALGO_GEA1, "GEA1" },
{ GPRS_ALGO_GEA2, "GEA2" },
{ GPRS_ALGO_GEA3, "GEA3" },
{ GPRS_ALGO_GEA4, "GEA4" },
{ 0, NULL },
};
/* register a cipher with the core */
int gprs_cipher_register(struct gprs_cipher_impl *ciph)
{
if (ciph->algo >= ARRAY_SIZE(selected_ciphers))
return -ERANGE;
llist_add_tail(&ciph->list, &gprs_ciphers);
/* check if we want to select this implementation over others */
if (!selected_ciphers[ciph->algo] ||
(selected_ciphers[ciph->algo]->priority > ciph->priority))
selected_ciphers[ciph->algo] = ciph;
return 0;
}
/* load all available GPRS cipher plugins */
int gprs_cipher_load(const char *path)
{
#if !defined(EMBEDDED)
/* load all plugins available from path */
if (path)
return osmo_plugin_load_all(path);
#endif
return 0;
}
/* function to be called by core code */
int gprs_cipher_run(uint8_t *out, uint16_t len, enum gprs_ciph_algo algo,
uint8_t *kc, uint32_t iv, enum gprs_cipher_direction dir)
{
if (algo >= ARRAY_SIZE(selected_ciphers))
return -ERANGE;
if (!selected_ciphers[algo])
return -EINVAL;
if (len > GSM0464_CIPH_MAX_BLOCK)
return -ERANGE;
/* run the actual cipher from the plugin */
return selected_ciphers[algo]->run(out, len, kc, iv, dir);
}
/*! Obtain key lenght for given GPRS cipher
* \param[in] algo Enum representive GPRS cipher
* \returns unsigned integer key length for supported algorithms,
* for GEA0 and unknown ciphers will return 0
*/
unsigned gprs_cipher_key_length(enum gprs_ciph_algo algo)
{
switch (algo) {
case GPRS_ALGO_GEA0: return 0;
case GPRS_ALGO_GEA1:
case GPRS_ALGO_GEA2:
case GPRS_ALGO_GEA3: return 8;
case GPRS_ALGO_GEA4: return 16;
default: return 0;
}
}
int gprs_cipher_supported(enum gprs_ciph_algo algo)
{
if (algo >= ARRAY_SIZE(selected_ciphers))
return -ERANGE;
if (selected_ciphers[algo])
return 1;
return 0;
}
/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
uint32_t gprs_cipher_gen_input_ui(uint32_t iov_ui, uint8_t sapi, uint32_t lfn, uint32_t oc)
{
uint32_t sx = ((1<<27) * sapi) + ((uint32_t ) 1<<31);
return (iov_ui ^ sx) + lfn + oc;
}
/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
uint32_t gprs_cipher_gen_input_i(uint32_t iov_i, uint32_t lfn, uint32_t oc)
{
return iov_i + lfn + oc;
}
/*! @} */
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