147 lines
3.8 KiB
C
147 lines
3.8 KiB
C
/* Authentication related functions */
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/*
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* (C) 2010 by Sylvain Munaut <tnt@246tNt.com>
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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 Affero General Public License as published by
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* the Free Software Foundation; either version 3 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 Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <openbsc/db.h>
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#include <openbsc/debug.h>
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#include <openbsc/auth.h>
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#include <openbsc/gsm_data.h>
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#include <osmocom/gsm/comp128.h>
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#include <openssl/rand.h>
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#include <stdlib.h>
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const struct value_string auth_action_names[] = {
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#define AUTH_ACTION_STR(X) { X, #X }
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{ -1, "(internal error)" }, /* soon to be fixed with an enum val */
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AUTH_ACTION_STR(AUTH_NOT_AVAIL),
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AUTH_ACTION_STR(AUTH_DO_AUTH_THEN_CIPH),
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AUTH_ACTION_STR(AUTH_DO_CIPH),
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AUTH_ACTION_STR(AUTH_DO_AUTH),
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#undef AUTH_ACTION_STR
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};
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static int
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_use_xor(struct gsm_auth_info *ainfo, struct gsm_auth_tuple *atuple)
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{
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int i, l = ainfo->a3a8_ki_len;
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if ((l > A38_XOR_MAX_KEY_LEN) || (l < A38_XOR_MIN_KEY_LEN)) {
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LOGP(DMM, LOGL_ERROR, "Invalid XOR key (len=%d) %s\n",
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ainfo->a3a8_ki_len,
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osmo_hexdump(ainfo->a3a8_ki, ainfo->a3a8_ki_len));
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return -1;
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}
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for (i=0; i<4; i++)
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atuple->sres[i] = atuple->rand[i] ^ ainfo->a3a8_ki[i];
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for (i=4; i<12; i++)
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atuple->kc[i-4] = atuple->rand[i] ^ ainfo->a3a8_ki[i];
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return 0;
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}
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static int
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_use_comp128_v1(struct gsm_auth_info *ainfo, struct gsm_auth_tuple *atuple)
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{
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if (ainfo->a3a8_ki_len != A38_COMP128_KEY_LEN) {
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LOGP(DMM, LOGL_ERROR, "Invalid COMP128v1 key (len=%d) %s\n",
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ainfo->a3a8_ki_len,
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osmo_hexdump(ainfo->a3a8_ki, ainfo->a3a8_ki_len));
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return -1;
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}
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comp128(ainfo->a3a8_ki, atuple->rand, atuple->sres, atuple->kc);
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return 0;
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}
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/* Return values
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* -1 -> Internal error
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* 0 -> Not available
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* 1 -> Tuple returned, need to do auth, then enable cipher
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* 2 -> Tuple returned, need to enable cipher
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*/
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int auth_get_tuple_for_subscr(struct gsm_auth_tuple *atuple,
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struct gsm_subscriber *subscr, int key_seq)
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{
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struct gsm_auth_info ainfo;
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int rc;
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/* Get subscriber info (if any) */
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rc = db_get_authinfo_for_subscr(&ainfo, subscr);
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if (rc < 0) {
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LOGP(DMM, LOGL_NOTICE,
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"No retrievable Ki for subscriber, skipping auth\n");
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return rc == -ENOENT ? AUTH_NOT_AVAIL : -1;
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}
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/* If possible, re-use the last tuple and skip auth */
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rc = db_get_lastauthtuple_for_subscr(atuple, subscr);
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if ((rc == 0) &&
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(key_seq != GSM_KEY_SEQ_INVAL) &&
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(atuple->use_count < 3))
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{
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atuple->use_count++;
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db_sync_lastauthtuple_for_subscr(atuple, subscr);
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DEBUGP(DMM, "Auth tuple use < 3, just doing ciphering\n");
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return AUTH_DO_CIPH;
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}
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/* Generate a new one */
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atuple->use_count = 1;
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atuple->key_seq = (atuple->key_seq + 1) % 7;
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if (RAND_bytes(atuple->rand, sizeof(atuple->rand)) != 1) {
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LOGP(DMM, LOGL_NOTICE, "RAND_bytes failed, can't generate new auth tuple\n");
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return -1;
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}
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switch (ainfo.auth_algo) {
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case AUTH_ALGO_NONE:
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DEBUGP(DMM, "No authentication for subscriber\n");
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return 0;
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case AUTH_ALGO_XOR:
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if (_use_xor(&ainfo, atuple))
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return 0;
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break;
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case AUTH_ALGO_COMP128v1:
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if (_use_comp128_v1(&ainfo, atuple))
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return 0;
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break;
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default:
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DEBUGP(DMM, "Unsupported auth type algo_id=%d\n",
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ainfo.auth_algo);
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return 0;
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}
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db_sync_lastauthtuple_for_subscr(atuple, subscr);
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DEBUGP(DMM, "Need to do authentication and ciphering\n");
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return AUTH_DO_AUTH_THEN_CIPH;
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}
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