pespin submitted this change.
5gc: Fix NG NAS ul_count not incremented
Since open5gs.git b9823196b5de3394b7a144569f186d7d62fad6f9, open5gs
properly validates received seq_nr (ul_count) of integrity protected
NG-NAS message to make sure it increases with each new UL message, in
order to protect against accepting replayed messages.
This made the 5gc testsuite fail since our NGAP/NG-NAS emulation was not
properly increasing ul_count when sending new messages, but always using
ul_count=0.
Change-Id: I7ea4460c902a5f612243e155a484acc89acd447f
---
M library/NG_CryptoFunctions.ttcn
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/library/NG_CryptoFunctions.ttcn b/library/NG_CryptoFunctions.ttcn
index b16029e..840ed91 100644
--- a/library/NG_CryptoFunctions.ttcn
+++ b/library/NG_CryptoFunctions.ttcn
@@ -307,13 +307,16 @@
var BIT4 sec_hdr_t;
var OCT4 mac;
var NG_NAS_UL_Message_Type nas_out;
-
- if (nus.use_enc == false and nus.use_int == false) {
- return nas_in;
- }
+ var OCT1 seq_nr;
if (nus.new_ctx) {
nus.tx_count := 0;
+ } else {
+ nus.tx_count := nus.tx_count + 1;
+ }
+
+ if (nus.use_enc == false and nus.use_int == false) {
+ return nas_in;
}
var octetstring nas_enc := enc_NG_NAS_UL_Message_Type(nas_in)
@@ -327,14 +330,15 @@
Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, "Not supported");
}
+ seq_nr := int2oct(nus.tx_count mod 256, 1);
sec_hdr_t := f_NG_NAS_determine_sec_hdr_t(nus.use_enc, nus.use_int, nus.new_ctx);
mac := f_NG_NAS_mac_calc(nus.alg_int, nus.k_nas_int, nus.tx_count,
bit2int(tsc_NG_RegResult_3GPP),
- f_tx_is_downlink(nus), '00'O & nas_enc);
+ f_tx_is_downlink(nus), seq_nr & nas_enc);
nas_out := valueof(cs_NG_SECURITY_PROTECTED_NAS_MESSAGE(tsc_EPD_GMM,
sec_hdr_t,
mac,
- int2oct(nus.tx_count, 1),
+ seq_nr,
nas_enc));
return nas_out;
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