mirror of https://gerrit.osmocom.org/libosmocore
128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/* GPRS LLC cipher core infrastructure */
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/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <errno.h>
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#include <stdint.h>
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#include <osmocom/core/utils.h>
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#include <osmocom/core/linuxlist.h>
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#include <osmocom/core/plugin.h>
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#include <osmocom/crypt/gprs_cipher.h>
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static LLIST_HEAD(gprs_ciphers);
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static struct gprs_cipher_impl *selected_ciphers[_GPRS_ALGO_NUM];
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const struct value_string gprs_cipher_names[] = {
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{ GPRS_ALGO_GEA0, "GEA0" },
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{ GPRS_ALGO_GEA1, "GEA1" },
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{ GPRS_ALGO_GEA2, "GEA2" },
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{ GPRS_ALGO_GEA3, "GEA3" },
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{ GPRS_ALGO_GEA4, "GEA4" },
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{ 0, NULL },
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};
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/* register a cipher with the core */
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int gprs_cipher_register(struct gprs_cipher_impl *ciph)
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{
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if (ciph->algo >= ARRAY_SIZE(selected_ciphers))
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return -ERANGE;
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llist_add_tail(&ciph->list, &gprs_ciphers);
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/* check if we want to select this implementation over others */
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if (!selected_ciphers[ciph->algo] ||
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(selected_ciphers[ciph->algo]->priority > ciph->priority))
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selected_ciphers[ciph->algo] = ciph;
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return 0;
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}
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/* load all available GPRS cipher plugins */
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int gprs_cipher_load(const char *path)
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{
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/* load all plugins available from path */
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if (path)
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return osmo_plugin_load_all(path);
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return 0;
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}
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/* function to be called by core code */
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int gprs_cipher_run(uint8_t *out, uint16_t len, enum gprs_ciph_algo algo,
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uint8_t *kc, uint32_t iv, enum gprs_cipher_direction dir)
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{
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if (algo >= ARRAY_SIZE(selected_ciphers))
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return -ERANGE;
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if (!selected_ciphers[algo])
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return -EINVAL;
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if (len > GSM0464_CIPH_MAX_BLOCK)
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return -ERANGE;
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/* run the actual cipher from the plugin */
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return selected_ciphers[algo]->run(out, len, kc, iv, dir);
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}
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/*! \brief Obtain key lenght for given GPRS cipher
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* \param[in] algo Enum representive GPRS cipher
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* \returns unsigned integer key length for supported algorithms,
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* for GEA0 and unknown ciphers will return 0
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*/
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unsigned gprs_cipher_key_length(enum gprs_ciph_algo algo)
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{
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switch (algo) {
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case GPRS_ALGO_GEA0: return 0;
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case GPRS_ALGO_GEA1:
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case GPRS_ALGO_GEA2:
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case GPRS_ALGO_GEA3: return 8;
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case GPRS_ALGO_GEA4: return 16;
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default: return 0;
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}
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}
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int gprs_cipher_supported(enum gprs_ciph_algo algo)
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{
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if (algo >= ARRAY_SIZE(selected_ciphers))
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return -ERANGE;
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if (selected_ciphers[algo])
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return 1;
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return 0;
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}
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/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
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uint32_t gprs_cipher_gen_input_ui(uint32_t iov_ui, uint8_t sapi, uint32_t lfn, uint32_t oc)
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{
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uint32_t sx = ((1<<27) * sapi) + ((uint32_t ) 1<<31);
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return (iov_ui ^ sx) + lfn + oc;
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}
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/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
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uint32_t gprs_cipher_gen_input_i(uint32_t iov_i, uint32_t lfn, uint32_t oc)
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{
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return iov_i + lfn + oc;
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}
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