gsm_04_08: Add a operation to enable ciphering on a lchan
This will take care of the auth/check/enable cipher sequence
and call a callback function when done.
Currently the negotiated Kc is saved but not re-used, so
there is an authentication each time ...
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/openbsc/src/auth.c b/openbsc/src/auth.c
new file mode 100644
index 0000000..5a54da0
--- /dev/null
+++ b/openbsc/src/auth.c
@@ -0,0 +1,103 @@
+/* Authentication related functions */
+
+/*
+ * (C) 2010 by Sylvain Munaut <tnt@246tNt.com>
+ *
+ * All Rights Reserved
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <openbsc/db.h>
+#include <openbsc/debug.h>
+#include <openbsc/gsm_data.h>
+
+#include <osmocore/comp128.h>
+
+#include <stdlib.h>
+
+
+static int
+_use_comp128_v1(struct gsm_auth_info *ainfo, struct gsm_auth_tuple *atuple)
+{
+ if (ainfo->a3a8_ki_len != A38_COMP128_KEY_LEN) {
+ DEBUGP(DMM, "Invalid COMP128v1 key (len=%d) %s",
+ ainfo->a3a8_ki_len,
+ hexdump(ainfo->a3a8_ki, ainfo->a3a8_ki_len));
+ return -1;
+ }
+
+ comp128(ainfo->a3a8_ki, atuple->rand, atuple->sres, atuple->kc);
+
+ return 0;
+}
+
+/* Return values
+ * -1 -> Internal error
+ * 0 -> Not available
+ * 1 -> Tuple returned, need to do auth, then enable cipher
+ * 2 -> Tuple returned, need to enable cipher
+ */
+int auth_get_tuple_for_subscr(struct gsm_auth_tuple *atuple,
+ struct gsm_subscriber *subscr, int key_seq)
+{
+ struct gsm_auth_info ainfo;
+ int i, rc;
+
+ /* Get subscriber info (if any) */
+ rc = db_get_authinfo_for_subscr(&ainfo, subscr);
+ if (rc < 0) {
+ DEBUGP(DMM, "No retrievable Ki for subscriber, skipping auth");
+ return rc == -ENOENT ? 0 : -1;
+ }
+
+ /* If possible, re-use the last tuple and skip auth */
+ rc = db_get_lastauthtuple_for_subscr(atuple, subscr);
+ if ((rc == 0) &&
+ (atuple->key_seq != GSM_KEY_SEQ_INVAL) &&
+ (atuple->use_count < 3))
+ {
+ atuple->use_count++;
+ db_sync_lastauthtuple_for_subscr(atuple, subscr);
+ return 2;
+ }
+
+ /* Generate a new one */
+ atuple->use_count = 1;
+ atuple->key_seq = (atuple->key_seq + 1) % 7;
+ for (i=0; i<sizeof(atuple->rand); i++)
+ atuple->rand[i] = random() & 0xff;
+
+ switch (ainfo.auth_algo) {
+ case AUTH_ALGO_NONE:
+ return 0;
+
+ case AUTH_ALGO_COMP128v1:
+ if (_use_comp128_v1(&ainfo, atuple))
+ return 0;
+ break;
+
+ default:
+ DEBUGP(DMM, "Unsupported auth type algo_id=%d\n",
+ ainfo.auth_algo);
+ return 0;
+ }
+
+ db_sync_lastauthtuple_for_subscr(atuple, subscr);
+
+ return 1;
+}
+