mobile: Add vty option to force rekeying for every new channel

Written-by: Tim Ehlers	<osmocom@ehlers.info>
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

6 files changed, 40 insertions, 3 deletions

diff --git a/src/host/layer23/include/osmocom/bb/mobile/settings.h b/src/host/layer23/include/osmocom/bb/mobile/settings.h
index e09d9084..6d446967 100644
--- a/src/host/layer23/include/osmocom/bb/mobile/settings.h
+++ b/src/host/layer23/include/osmocom/bb/mobile/settings.h
@@ -87,6 +87,7 @@ struct gsm_settings {
 
 	/* radio */
 	uint16_t		dsc_max;
+	uint8_t			force_rekey;
 
 	/* dialing */
 	struct llist_head	abbrev;
diff --git a/src/host/layer23/include/osmocom/bb/mobile/subscriber.h b/src/host/layer23/include/osmocom/bb/mobile/subscriber.h
index 50c305a8..3e50e29d 100644
--- a/src/host/layer23/include/osmocom/bb/mobile/subscriber.h
+++ b/src/host/layer23/include/osmocom/bb/mobile/subscriber.h
@@ -105,6 +105,7 @@ int gsm_subscr_dump_forbidden_plmn(struct osmocom_ms *ms,
 void gsm_subscr_dump(struct gsm_subscriber *subscr,
 			void (*print)(void *, const char *, ...), void *priv);
 char *gsm_check_imsi(const char *imsi);
+int gsm_subscr_get_key_seq(struct osmocom_ms *ms, struct gsm_subscriber *subscr);
 
 #endif /* _SUBSCRIBER_H */
 
diff --git a/src/host/layer23/src/mobile/gsm48_mm.c b/src/host/layer23/src/mobile/gsm48_mm.c
index 76b9c261..a8f699d2 100644
--- a/src/host/layer23/src/mobile/gsm48_mm.c
+++ b/src/host/layer23/src/mobile/gsm48_mm.c
@@ -2344,7 +2344,7 @@ static int gsm48_mm_tx_loc_upd_req(struct osmocom_ms *ms)
 	/* location updating type */
 	nlu->type = mm->lupd_type;
 	/* cipering key */
-	nlu->key_seq = subscr->key_seq;
+	nlu->key_seq = gsm_subscr_get_key_seq(ms, subscr);
 	/* LAI (last SIM stored LAI)
 	 *
 	 * NOTE: The TMSI is only valid within a LAI!
@@ -2806,7 +2806,7 @@ static int gsm48_mm_tx_cm_serv_req(struct osmocom_ms *ms, int rr_prim,
 
 	/* type and key */
 	nsr->cm_service_type = cm_serv;
-	nsr->cipher_key_seq = subscr->key_seq;
+	nsr->cipher_key_seq = gsm_subscr_get_key_seq(ms, subscr);
 	/* classmark 2 */
 	cm2lv[0] = sizeof(struct gsm48_classmark2);
 	gsm48_rr_enc_cm2(ms, (struct gsm48_classmark2 *)(cm2lv + 1),
diff --git a/src/host/layer23/src/mobile/gsm48_rr.c b/src/host/layer23/src/mobile/gsm48_rr.c
index 5000d3ca..b6083afe 100644
--- a/src/host/layer23/src/mobile/gsm48_rr.c
+++ b/src/host/layer23/src/mobile/gsm48_rr.c
@@ -3251,7 +3251,7 @@ static int gsm48_rr_dl_est(struct osmocom_ms *ms)
 		gh->msg_type = GSM48_MT_RR_PAG_RESP;
 		pr = (struct gsm48_pag_rsp *) msgb_put(nmsg, sizeof(*pr));
 		/* key sequence */
-		pr->key_seq = subscr->key_seq;
+		pr->key_seq = gsm_subscr_get_key_seq(ms, subscr);
 		/* classmark 2 */
 		pr->cm2_len = sizeof(pr->cm2);
 		gsm48_rr_enc_cm2(ms, &pr->cm2, rr->cd_now.arfcn);
diff --git a/src/host/layer23/src/mobile/subscriber.c b/src/host/layer23/src/mobile/subscriber.c
index b6dfc2f0..8ebb1738 100644
--- a/src/host/layer23/src/mobile/subscriber.c
+++ b/src/host/layer23/src/mobile/subscriber.c
@@ -1144,6 +1144,14 @@ int gsm_subscr_is_forbidden_plmn(struct gsm_subscriber *subscr, uint16_t mcc,
 	return 0;
 }
 
+int gsm_subscr_get_key_seq(struct osmocom_ms *ms, struct gsm_subscriber *subscr)
+{
+	if (ms->settings.force_rekey)
+		return 7;
+	else
+		return subscr->key_seq;
+}
+
 int gsm_subscr_dump_forbidden_plmn(struct osmocom_ms *ms,
 			void (*print)(void *, const char *, ...), void *priv)
 {
diff --git a/src/host/layer23/src/mobile/vty_interface.c b/src/host/layer23/src/mobile/vty_interface.c
index ca1c5828..dc9e09d9 100644
--- a/src/host/layer23/src/mobile/vty_interface.c
+++ b/src/host/layer23/src/mobile/vty_interface.c
@@ -1300,6 +1300,9 @@ static void config_write_ms(struct vty *vty, struct osmocom_ms *ms)
 	if (!hide_default || set->auto_answer)
 		vty_out(vty, " %sauto-answer%s",
 			(set->auto_answer) ? "" : "no ", VTY_NEWLINE);
+	if (!hide_default || set->force_rekey)
+		vty_out(vty, " %sforce-rekey%s",
+			(set->force_rekey) ? "" : "no ", VTY_NEWLINE);
 	if (!hide_default || set->clip)
 		vty_out(vty, " %sclip%s", (set->clip) ? "" : "no ",
 			VTY_NEWLINE);
@@ -1730,6 +1733,28 @@ DEFUN(cfg_auto_answer, cfg_ms_auto_answer_cmd, "auto-answer",
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_no_force_rekey, cfg_ms_no_force_rekey_cmd, "no force-rekey",
+	NO_STR "Disable key renew forcing after every event")
+{
+	struct osmocom_ms *ms = vty->index;
+	struct gsm_settings *set = &ms->settings;
+
+	set->force_rekey = 0;
+
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_force_rekey, cfg_ms_force_rekey_cmd, "force-rekey",
+	"Enable key renew forcing after every event")
+{
+	struct osmocom_ms *ms = vty->index;
+	struct gsm_settings *set = &ms->settings;
+
+	set->force_rekey = 1;
+
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_clip, cfg_ms_clip_cmd, "clip",
 	"Force caller ID presentation")
 {
@@ -2782,6 +2807,8 @@ int ms_vty_init(void)
 	install_element(MS_NODE, &cfg_ms_no_cw_cmd);
 	install_element(MS_NODE, &cfg_ms_auto_answer_cmd);
 	install_element(MS_NODE, &cfg_ms_no_auto_answer_cmd);
+	install_element(MS_NODE, &cfg_ms_force_rekey_cmd);
+	install_element(MS_NODE, &cfg_ms_no_force_rekey_cmd);
 	install_element(MS_NODE, &cfg_ms_clip_cmd);
 	install_element(MS_NODE, &cfg_ms_clir_cmd);
 	install_element(MS_NODE, &cfg_ms_no_clip_cmd);