Make UTRAN encryption algorithms configurable

Allow the user fine-grained control over which UMTS encryption
algorithms are permitted, rather than always permitting UEA1 and UEA2
or neither.

This brings the handling of UEA in line with the handling of A5 for
GERAN.

Change-Id: I91f9e50f9c1439aa19528f887b83ae9de628fcfd
Closes: OS#4144
Depends: osmo-iuh.git I6d2d033b0427bdc84fee61e0f3cb7b29935214bf

5 files changed, 24 insertions, 37 deletions

diff --git a/src/libmsc/gsm_04_08.c b/src/libmsc/gsm_04_08.c
index 565e7adb7..fc1b2e204 100644
--- a/src/libmsc/gsm_04_08.c
+++ b/src/libmsc/gsm_04_08.c
@@ -414,7 +414,7 @@ static int mm_rx_loc_upd_req(struct msc_a *msc_a, struct msgb *msg)
 				net->vlr, msc_a, vlr_lu_type, tmsi, imsi,
 				&old_lai, &msc_a->via_cell.lai,
 				is_utran || net->authentication_required,
-				is_utran ? net->uea_encryption : net->a5_encryption_mask > 0x01,
+				is_utran ? net->uea_encryption_mask > 0x01 : net->a5_encryption_mask > 0x01,
 				lu->key_seq,
 				osmo_gsm48_classmark1_is_r99(&lu->classmark1),
 				is_utran,
@@ -805,7 +805,7 @@ int gsm48_rx_mm_serv_req(struct msc_a *msc_a, struct msgb *msg)
 			 req->cm_service_type,
 			 &mi, &msc_a->via_cell.lai,
 			 is_utran || net->authentication_required,
-			 is_utran ? net->uea_encryption : net->a5_encryption_mask > 0x01,
+			 is_utran ? net->uea_encryption_mask > 0x01 : net->a5_encryption_mask > 0x01,
 			 req->cipher_key_seq,
 			 osmo_gsm48_classmark2_is_r99(cm2, cm2_len),
 			 is_utran);
@@ -931,7 +931,7 @@ static int gsm48_rx_cm_reest_req(struct msc_a *msc_a, struct msgb *msg)
 			 VLR_PR_ARQ_T_CM_RE_ESTABLISH_REQ, 0,
 			 &mi, &msc_a->via_cell.lai,
 			 is_utran || net->authentication_required,
-			 is_utran ? net->uea_encryption : net->a5_encryption_mask > 0x01,
+			 is_utran ? net->uea_encryption_mask > 0x01 : net->a5_encryption_mask > 0x01,
 			 req->cipher_key_seq,
 			 osmo_gsm48_classmark2_is_r99(cm2, cm2_len),
 			 is_utran);
@@ -1293,7 +1293,7 @@ static int gsm48_rx_rr_pag_resp(struct msc_a *msc_a, struct msgb *msg)
 			 net->vlr, msc_a,
 			 VLR_PR_ARQ_T_PAGING_RESP, 0, &mi, &msc_a->via_cell.lai,
 			 is_utran || net->authentication_required,
-			 is_utran ? net->uea_encryption : net->a5_encryption_mask > 0x01,
+			 is_utran ? net->uea_encryption_mask > 0x01 : net->a5_encryption_mask > 0x01,
 			 pr->key_seq,
 			 osmo_gsm48_classmark2_is_r99(cm2, classmark2_len),
 			 is_utran);
diff --git a/src/libmsc/msc_a.c b/src/libmsc/msc_a.c
index fe3af14e4..a79cf6aa9 100644
--- a/src/libmsc/msc_a.c
+++ b/src/libmsc/msc_a.c
@@ -349,8 +349,8 @@ static int msc_a_ran_enc_ciphering(struct msc_a *msc_a, bool umts_aka, bool retr
 				.chosen_key = &msc_a->geran_encr,
 			},
 			.utran = {
-				.uea_encryption = net->uea_encryption
-			}
+				.uea_encryption_mask = net->uea_encryption_mask,
+			},
 		},
 	};
 
diff --git a/src/libmsc/msc_net_init.c b/src/libmsc/msc_net_init.c
index 9e3e8b34f..d53156b8a 100644
--- a/src/libmsc/msc_net_init.c
+++ b/src/libmsc/msc_net_init.c
@@ -67,7 +67,8 @@ struct gsm_network *gsm_network_init(void *ctx, mncc_recv_cb_t mncc_recv)
 
 	/* Permit a compile-time default of A5/3 and A5/1 */
 	net->a5_encryption_mask = (1 << 3) | (1 << 1);
-	net->uea_encryption = true;
+	/* Permit a compile-time default of UEA2 and UEA1 */
+	net->uea_encryption_mask = (1 << 2) | (1 << 1);
 
 	net->mncc_guard_timeout = 180;
 	net->ncss_guard_timeout = 30;
diff --git a/src/libmsc/msc_vty.c b/src/libmsc/msc_vty.c
index e4e093741..6be09d8ed 100644
--- a/src/libmsc/msc_vty.c
+++ b/src/libmsc/msc_vty.c
@@ -169,41 +169,21 @@ DEFUN(cfg_net_encryption,
 	return CMD_SUCCESS;
 }
 
-/* So far just a boolean switch, a future patch might add individual config for UEA1 and UEA2, see OS#4143 */
 DEFUN(cfg_net_encryption_uea,
       cfg_net_encryption_uea_cmd,
       "encryption uea <0-2> [<0-2>] [<0-2>]",
       ENCRYPTION_STR
-      "UTRAN (3G) encryption algorithms to allow: 0 = UEA0 (no encryption), 1 = UEA1, 2 = UEA2."
-        " NOTE: the current implementation does not allow free choice of combining encryption algorithms yet."
-	" The only valid settings are either 'encryption uea 0' or 'encryption uea 1 2'.\n"
+      "UTRAN (3G) encryption algorithms to allow: 0 = UEA0 (no encryption), 1 = UEA1, 2 = UEA2.\n"
       "UEAn Algorithm Number\n"
       "UEAn Algorithm Number\n"
       "UEAn Algorithm Number\n"
      )
 {
 	unsigned int i;
-	uint8_t mask = 0;
 
+	gsmnet->uea_encryption_mask = 0;
 	for (i = 0; i < argc; i++)
-		mask |= (1 << atoi(argv[i]));
-
-	if (mask == (1 << 0)) {
-		/* UEA0. Disable encryption. */
-		gsmnet->uea_encryption = false;
-	} else if (mask == ((1 << 1) | (1 << 2))) {
-		/* UEA1 and UEA2. Enable encryption. */
-		gsmnet->uea_encryption = true;
-	} else {
-		vty_out(vty,
-			"%% Error: the current implementation does not allow free choice of combining%s"
-			"%% encryption algorithms yet. The only valid settings are either%s"
-			"%%   encryption uea 0%s"
-			"%% or%s"
-			"%%   encryption uea 1 2%s",
-			VTY_NEWLINE, VTY_NEWLINE, VTY_NEWLINE, VTY_NEWLINE, VTY_NEWLINE);
-		return CMD_WARNING;
-	}
+		gsmnet->uea_encryption_mask |= (1 << atoi(argv[i]));
 
 	return CMD_SUCCESS;
 }
@@ -386,10 +366,12 @@ static int config_write_net(struct vty *vty)
 	}
 	vty_out(vty, "%s", VTY_NEWLINE);
 
-	if (!gsmnet->uea_encryption)
-		vty_out(vty, " encryption uea 0%s", VTY_NEWLINE);
-	else
-		vty_out(vty, " encryption uea 1 2%s", VTY_NEWLINE);
+	vty_out(vty, " encryption uea");
+	for (i = 0; i < 8; i++) {
+		if (gsmnet->uea_encryption_mask & (1 << i))
+			vty_out(vty, " %u", i);
+	}
+	vty_out(vty, "%s", VTY_NEWLINE);
 	vty_out(vty, " authentication %s%s",
 		gsmnet->authentication_required ? "required" : "optional", VTY_NEWLINE);
 	vty_out(vty, " rrlp mode %s%s", msc_rrlp_mode_name(gsmnet->rrlp.mode),
diff --git a/src/libmsc/ran_msg_iu.c b/src/libmsc/ran_msg_iu.c
index 6120918d9..7b3dd1c01 100644
--- a/src/libmsc/ran_msg_iu.c
+++ b/src/libmsc/ran_msg_iu.c
@@ -367,9 +367,13 @@ static struct msgb *ran_iu_make_security_mode_command(struct osmo_fsm_inst *call
 						      const struct ran_cipher_mode_command *cm)
 {
 
-	LOG_RAN_IU_ENC(caller_fi, LOGL_DEBUG, "Tx RANAP SECURITY MODE COMMAND to RNC, ik %s\n",
-			osmo_hexdump_nospc(cm->vec->ik, 16));
-	return ranap_new_msg_sec_mod_cmd(cm->vec->ik, cm->utran.uea_encryption ? cm->vec->ck : NULL, RANAP_KeyStatus_new);
+	LOG_RAN_IU_ENC(caller_fi, LOGL_DEBUG, "Tx RANAP SECURITY MODE COMMAND to RNC, IK=%s, CK=%s\n",
+			osmo_hexdump_nospc(cm->vec->ik, 16),
+			cm->utran.uea_encryption_mask > 0x01 ? osmo_hexdump_nospc(cm->vec->ck, 16) : "NONE");
+	/* TODO: Do we need to check if the UE supports all of the algorithms and build an intersection like
+	 * in the case of A5? */
+	return ranap_new_msg_sec_mod_cmd2(cm->vec->ik, cm->utran.uea_encryption_mask > 0x01 ? cm->vec->ck : NULL,
+					  RANAP_KeyStatus_new, 0x06, cm->utran.uea_encryption_mask);
 }