SGSN: add preliminary support for GPRS encryption
It is already functional enough to allow testing with real
phones. However, note - there are several limitations in the current
implementation:
* only default value for IOV-UI is supported at the moment
* AUTN-based key material is not supported
Related: OS#1582
Change-Id: I8900b906693496e4e6b35be5a86937c58039ed9e
diff --git a/openbsc/src/gprs/gprs_llc.c b/openbsc/src/gprs/gprs_llc.c
index b271e21..bc856e9 100644
--- a/openbsc/src/gprs/gprs_llc.c
+++ b/openbsc/src/gprs/gprs_llc.c
@@ -22,6 +22,8 @@
#include <errno.h>
#include <stdint.h>
+#include <openssl/rand.h>
+
#include <osmocom/core/msgb.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/timer.h>
@@ -598,7 +600,8 @@
case GPRS_SAPI_SNDCP9:
case GPRS_SAPI_SNDCP11:
/* Ask an upper layer for help. */
- return sgsn_force_reattach_oldmsg(msg);
+ return gsm0408_gprs_force_reattach_oldmsg(msg,
+ lle->llme);
default:
break;
}
@@ -769,13 +772,18 @@
int gprs_llgmm_reset(struct gprs_llc_llme *llme)
{
struct msgb *msg = msgb_alloc_headroom(4096, 1024, "LLC_XID");
- int random = rand();
struct gprs_llc_lle *lle = &llme->lle[1];
+ if (RAND_bytes((uint8_t *) &llme->iov_ui, 4) != 1) {
+ LOGP(DLLC, LOGL_NOTICE, "RAND_bytes failed for LLC XID reset, "
+ "falling back to rand()\n");
+ llme->iov_ui = rand();
+ }
+
/* First XID component must be RESET */
msgb_put_xid_par(msg, GPRS_LLC_XID_T_RESET, 0, NULL);
/* randomly select new IOV-UI */
- msgb_put_xid_par(msg, GPRS_LLC_XID_T_IOV_UI, 4, (uint8_t *) &random);
+ msgb_put_xid_par(msg, GPRS_LLC_XID_T_IOV_UI, 4, (uint8_t *) &llme->iov_ui);
/* Reset some of the LLC parameters. See GSM 04.64, 8.5.3.1 */
lle->vu_recv = 0;
@@ -787,15 +795,21 @@
return gprs_llc_tx_xid(lle, msg, 1);
}
-int gprs_llgmm_reset_oldmsg(struct msgb* oldmsg, uint8_t sapi)
+int gprs_llgmm_reset_oldmsg(struct msgb* oldmsg, uint8_t sapi,
+ struct gprs_llc_llme *llme)
{
struct msgb *msg = msgb_alloc_headroom(4096, 1024, "LLC_XID");
- int random = rand();
+
+ if (RAND_bytes((uint8_t *) &llme->iov_ui, 4) != 1) {
+ LOGP(DLLC, LOGL_NOTICE, "RAND_bytes failed for LLC XID reset, "
+ "falling back to rand()\n");
+ llme->iov_ui = rand();
+ }
/* First XID component must be RESET */
msgb_put_xid_par(msg, GPRS_LLC_XID_T_RESET, 0, NULL);
/* randomly select new IOV-UI */
- msgb_put_xid_par(msg, GPRS_LLC_XID_T_IOV_UI, 4, (uint8_t *) &random);
+ msgb_put_xid_par(msg, GPRS_LLC_XID_T_IOV_UI, 4, (uint8_t *) &llme->iov_ui);
/* FIXME: Start T200, wait for XID response */