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/gsm_04_08.c b/openbsc/src/gsm_04_08.c
index ed2b4e5..2563158 100644
--- a/openbsc/src/gsm_04_08.c
+++ b/openbsc/src/gsm_04_08.c
@@ -30,6 +30,7 @@
#include <time.h>
#include <netinet/in.h>
+#include <openbsc/auth.h>
#include <openbsc/db.h>
#include <osmocore/msgb.h>
#include <osmocore/bitvec.h>
@@ -54,6 +55,7 @@
#include <openbsc/silent_call.h>
void *tall_locop_ctx;
+void *tall_authciphop_ctx;
int gsm0408_loc_upd_acc(struct gsm_lchan *lchan, u_int32_t tmsi);
static int gsm48_tx_simple(struct gsm_lchan *lchan,
@@ -68,6 +70,91 @@
static u_int32_t new_callref = 0x80000001;
+
+static void release_security_operation(struct gsm_subscriber_connection *conn)
+{
+ if (!conn->sec_operation)
+ return;
+
+ talloc_free(conn->sec_operation);
+ conn->sec_operation = NULL;
+ put_subscr_con(conn);
+}
+
+static void allocate_security_operation(struct gsm_subscriber_connection *conn)
+{
+ use_subscr_con(conn)
+
+ conn->sec_operation = talloc_zero(tall_authciphop_ctx,
+ struct gsm_security_operation);
+}
+
+int gsm48_secure_channel(struct gsm_lchan *lchan, int key_seq,
+ gsm_cbfn *cb, void *cb_data)
+{
+ struct gsm_network *net = lchan->ts->trx->bts->network;
+ struct gsm_subscriber *subscr = lchan->conn.subscr;
+ struct gsm_security_operation *op;
+ struct gsm_auth_tuple atuple;
+ int status = -1, rc;
+
+ /* Check if we _can_ enable encryption. Cases where we can't:
+ * - Encryption disabled in config
+ * - Channel already secured (nothing to do)
+ * - Subscriber equipment doesn't support configured encryption
+ */
+ if (!net->a5_encryption) {
+ status = GSM_SECURITY_NOAVAIL;
+ } else if (lchan->encr.alg_id > RSL_ENC_ALG_A5(0)) {
+ DEBUGP(DMM, "Requesting to secure an already secure channel");
+ status = GSM_SECURITY_SUCCEEDED;
+ } else if (!ms_cm2_a5n_support(subscr->equipment.classmark2,
+ net->a5_encryption)) {
+ DEBUGP(DMM, "Subscriber equipment doesn't support requested encryption");
+ status = GSM_SECURITY_NOAVAIL;
+ }
+
+ /* If not done yet, try to get info for this user */
+ if (status < 0) {
+ rc = auth_get_tuple_for_subscr(&atuple, subscr, key_seq);
+ if (rc <= 0)
+ status = GSM_SECURITY_NOAVAIL;
+ }
+
+ /* Are we done yet ? */
+ if (status >= 0)
+ return cb ?
+ cb(GSM_HOOK_RR_SECURITY, status, NULL, lchan, cb_data) :
+ 0;
+
+ /* Start an operation (can't have more than one pending !!!) */
+ if (lchan->conn.sec_operation)
+ return -EBUSY;
+
+ allocate_security_operation(&lchan->conn);
+ op = lchan->conn.sec_operation;
+ op->cb = cb;
+ op->cb_data = cb_data;
+ memcpy(&op->atuple, &atuple, sizeof(struct gsm_auth_tuple));
+
+ /* FIXME: Should start a timer for completion ... */
+
+ /* Then do whatever is needed ... */
+ if (rc == 1) {
+ /* Start authentication */
+ return gsm48_tx_mm_auth_req(lchan, op->atuple.rand, op->atuple.key_seq);
+ } else if (rc == 2) {
+ /* Start ciphering directly */
+ lchan->encr.alg_id = RSL_ENC_ALG_A5(net->a5_encryption);
+ lchan->encr.key_len = 8;
+ memcpy(lchan->encr.key, op->atuple.kc, 8);
+
+ return gsm48_send_rr_ciph_mode(lchan, 0);
+ }
+
+ return -EINVAL; /* not reached */
+}
+
static int authorize_subscriber(struct gsm_loc_updating_operation *loc,
struct gsm_subscriber *subscriber)
{
@@ -160,6 +247,7 @@
return 0;
release_loc_updating_req(&lchan->conn);
+ release_security_operation(&lchan->conn);
/* Free all transactions that are associated with the released lchan */
/* FIXME: this is not neccessarily the right thing to do, we should
@@ -735,6 +823,43 @@
return 0;
}
+/* Chapter 9.2.3: Authentication Response */
+static int gsm48_rx_mm_auth_resp(struct msgb *msg)
+{
+ struct gsm48_hdr *gh = msgb_l3(msg);
+ struct gsm48_auth_resp *ar = (struct gsm48_auth_resp*) gh->data;
+ struct gsm_lchan *lchan = msg->lchan;
+ struct gsm_subscriber_connection *conn = &msg->lchan->conn;
+ struct gsm_network *net = lchan->ts->trx->bts->network;
+
+ DEBUGP(DMM, "MM AUTHENTICATION RESPONSE (sres = %s)\n",
+ hexdump(ar->sres, 4));
+
+ /* Safety check */
+ if (!conn->sec_operation) {
+ DEBUGP(DMM, "No authentication/cipher operation in progress !!!\n");
+ return -EIO;
+ }
+
+ /* Validate SRES */
+ if (memcmp(conn->sec_operation->atuple.sres, ar->sres,4)) {
+ gsm_cbfn *cb = conn->sec_operation->cb;
+ if (cb)
+ cb(GSM_HOOK_RR_SECURITY, GSM_SECURITY_AUTH_FAILED,
+ NULL, lchan, conn->sec_operation->cb_data);
+
+ release_security_operation(conn);
+ return gsm48_tx_mm_auth_rej(lchan);
+ }
+
+ /* Start ciphering */
+ lchan->encr.alg_id = RSL_ENC_ALG_A5(net->a5_encryption);
+ lchan->encr.key_len = 8;
+ memcpy(msg->lchan->encr.key, conn->sec_operation->atuple.kc, 8);
+
+ return gsm48_send_rr_ciph_mode(msg->lchan, 0);
+}
+
/* Receive a GSM 04.08 Mobility Management (MM) message */
static int gsm0408_rcv_mm(struct msgb *msg)
{
@@ -768,7 +893,7 @@
DEBUGP(DMM, "CM REESTABLISH REQUEST: Not implemented\n");
break;
case GSM48_MT_MM_AUTH_RESP:
- DEBUGP(DMM, "AUTHENTICATION RESPONSE: Not implemented\n");
+ rc = gsm48_rx_mm_auth_resp(msg);
break;
default:
LOGP(DMM, LOGL_NOTICE, "Unknown GSM 04.08 MM msg type 0x%02x\n",
@@ -910,6 +1035,37 @@
return db_apdu_blob_store(msg->lchan->conn.subscr, apdu_id_flags, apdu_len, apdu_data);
}
+/* Chapter 9.1.10 Ciphering Mode Complete */
+static int gsm48_rx_rr_ciph_m_compl(struct msgb *msg)
+{
+ struct gsm_lchan *lchan = msg->lchan;
+ struct gsm_subscriber_connection *conn = &lchan->conn;
+ gsm_cbfn *cb;
+ int rc = 0;
+
+ DEBUGP(DRR, "CIPHERING MODE COMPLETE\n");
+
+ /* Safety check */
+ if (!conn->sec_operation) {
+ DEBUGP(DRR, "No authentication/cipher operation in progress !!!\n");
+ return -EIO;
+ }
+
+ /* FIXME: check for MI (if any) */
+
+ /* Call back whatever was in progress (if anything) ... */
+ cb = conn->sec_operation->cb;
+ if (cb) {
+ rc = cb(GSM_HOOK_RR_SECURITY, GSM_SECURITY_SUCCEEDED,
+ NULL, lchan, conn->sec_operation->cb_data);
+ }
+
+ /* Complete the operation */
+ release_security_operation(conn);
+
+ return rc;
+}
+
/* Chapter 9.1.16 Handover complete */
static int gsm48_rx_rr_ho_compl(struct msgb *msg)
{
@@ -967,8 +1123,7 @@
rc = gsm48_rx_rr_app_info(msg);
break;
case GSM48_MT_RR_CIPH_M_COMPL:
- DEBUGP(DRR, "CIPHERING MODE COMPLETE\n");
- /* FIXME: check for MI (if any) */
+ rc = gsm48_rx_rr_ciph_m_compl(msg);
break;
case GSM48_MT_RR_HANDO_COMPL:
rc = gsm48_rx_rr_ho_compl(msg);