Change in osmo-msc[master]: ran_msg_iu: do not pass UEA0 to ranap_new_msg_sec_mod_cmd2()

[fixeria]

fixeria has submitted this change. ( https://gerrit.osmocom.org/c/osmo-msc/+/26391 )

Change subject: ran_msg_iu: do not pass UEA0 to ranap_new_msg_sec_mod_cmd2()
......................................................................

ran_msg_iu: do not pass UEA0 to ranap_new_msg_sec_mod_cmd2()

On the protocol level, it's impossible to indicate UEA0 together
with the other algorithms.  The encryption is either a) disabled,
so the Encryption Information IE is not present, or b) enabled,
so the Encryption Information IE indicates UEA1 and/or UEA2.

Because of that, the ranap_new_msg_sec_mod_cmd2() would fail to
generate the RANAP PDU if the given bitmask has the UEA0 bit set.

Fixes: 505a94a610fc ("Make UTRAN encryption algorithms configurable")
Change-Id: I3271d27c09fc8d70a912bce998ceffbce64dd95e
---
M src/libmsc/ran_msg_iu.c
1 file changed, 3 insertions(+), 2 deletions(-)

Approvals:
  laforge: Looks good to me, but someone else must approve
  fixeria: Looks good to me, approved
  pespin: Looks good to me, but someone else must approve
  Jenkins Builder: Verified



diff --git a/src/libmsc/ran_msg_iu.c b/src/libmsc/ran_msg_iu.c
index cf57d35..b894df2 100644
--- a/src/libmsc/ran_msg_iu.c
+++ b/src/libmsc/ran_msg_iu.c
@@ -377,7 +377,8 @@
 {
 	/* TODO: make the choice of available UIA algorithms configurable */
 	const uint8_t uia_mask = (1 << OSMO_UTRAN_UIA1) | (1 << OSMO_UTRAN_UIA2);
-	bool use_encryption = cm->utran.uea_encryption_mask > (1 << OSMO_UTRAN_UEA0);
+	const uint8_t uea_mask = cm->utran.uea_encryption_mask & ~(1 << OSMO_UTRAN_UEA0);
+	bool use_encryption = uea_mask != 0x00;
 
 	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),
@@ -388,7 +389,7 @@
 					  use_encryption ? cm->vec->ck : NULL,
 					  RANAP_KeyStatus_new,
 					  (uia_mask << 1), /* API treats LSB as UIA0 */
-					  cm->utran.uea_encryption_mask);
+					  uea_mask);
 }
 
 

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Gerrit-Project: osmo-msc
Gerrit-Branch: master
Gerrit-Change-Id: I3271d27c09fc8d70a912bce998ceffbce64dd95e
Gerrit-Change-Number: 26391
Gerrit-PatchSet: 5
Gerrit-Owner: lynxis lazus <lynxis at fe80.eu>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria <vyanitskiy at sysmocom.de>
Gerrit-Reviewer: laforge <laforge at osmocom.org>
Gerrit-Reviewer: neels <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: pespin <pespin at sysmocom.de>
Gerrit-MessageType: merged
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