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neels gerrit-no-reply at lists.osmocom.orgneels has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/24758 )
Change subject: msc: cipher mode: move cipher expect to new function
......................................................................
msc: cipher mode: move cipher expect to new function
Move the ciphering calculations from f_mm_common() to new function
f_get_expected_encryption(), so that it can be re-used for ciphering in
inter-BSC handover (upcoming patch).
Add tr_BSSMAP_CipherModeCmd2() to conveniently use the values returned
by f_get_expected_encryption().
To verify the Ciphering Mode Command in f_mm_common(), use the new
tr_BSSMAP_CipherModeCmd2(), and rely on template matching instead of
checking each IE individually.
Related: SYS#5324
Change-Id: I1f775889fb801d441ea6c8b0f0c34718b814c09e
---
M library/BSSMAP_Templates.ttcn
M msc/BSC_ConnectionHandler.ttcn
2 files changed, 56 insertions(+), 29 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-ttcn3-hacks refs/changes/58/24758/1
diff --git a/library/BSSMAP_Templates.ttcn b/library/BSSMAP_Templates.ttcn
index 1dcbef1..cde0fb0 100644
--- a/library/BSSMAP_Templates.ttcn
+++ b/library/BSSMAP_Templates.ttcn
@@ -546,6 +546,11 @@
}
}
+template BSSMAP_IE_KC128 tr_BSSMAP_IE_Kc128(template OCT16 kc128) := {
+ elementIdentifier := '83'O,
+ kC128_Value := kc128
+}
+
template (value) BSSMAP_IE_KC128 ts_BSSMAP_IE_Kc128(OCT16 kc128) := {
elementIdentifier := '83'O,
kC128_Value := kc128
@@ -1398,21 +1403,25 @@
}
}
-template PDU_BSSAP tr_BSSMAP_CipherModeCmd(template OCT1 alg, template OCT8 key)
+template PDU_BSSAP tr_BSSMAP_CipherModeCmd2(template BSSMAP_IE_EncryptionInformation encryptionInformation := *,
+ template BSSMAP_IE_KC128 kC128 := *)
modifies tr_BSSAP_BSSMAP := {
pdu := {
bssmap := {
cipherModeCommand := {
messageType := '53'O,
layer3HeaderInfo := *,
- encryptionInformation := tr_BSSMAP_IE_EncrInfo(key, alg),
+ encryptionInformation := encryptionInformation,
cipherResponseMode := *,
- kC128 := *
+ kC128 := kC128
}
}
}
}
+template PDU_BSSAP tr_BSSMAP_CipherModeCmd(template OCT1 alg, template OCT8 key, template BSSMAP_IE_KC128 kC128 := omit)
+ := tr_BSSMAP_CipherModeCmd2(tr_BSSMAP_IE_EncrInfo(key, alg), kC128);
+
template PDU_BSSAP ts_BSSMAP_CipherModeCompl(OCT1 alg)
modifies ts_BSSAP_BSSMAP := {
pdu := {
diff --git a/msc/BSC_ConnectionHandler.ttcn b/msc/BSC_ConnectionHandler.ttcn
index 01db3d0..be72399 100644
--- a/msc/BSC_ConnectionHandler.ttcn
+++ b/msc/BSC_ConnectionHandler.ttcn
@@ -560,44 +560,62 @@
return res;
}
+function f_get_expected_encryption(
+ out template BSSMAP_IE_EncryptionInformation encryptionInformation,
+ out template BSSMAP_IE_ChosenEncryptionAlgorithm chosenEncryptionAlgorithm,
+ out template BSSMAP_IE_KC128 kC128,
+ out OCT1 a5_perm_alg)
+ runs on BSC_ConnHdlr
+{
+ var OCT1 a5_ms := f_alg_mask_from_cm(g_pars.cm2, g_pars.cm3);
+ a5_perm_alg := g_pars.net.kc_support and4b a5_ms;
+
+ if (not g_pars.net.expect_ciph) {
+ encryptionInformation := *;
+ chosenEncryptionAlgorithm := *;
+ kC128 := *;
+ return;
+ }
+
+ encryptionInformation := tr_BSSMAP_IE_EncrInfo(g_pars.vec.kc, a5_perm_alg);
+
+ var OCT1 chosen_alg := int2oct(f_alg_from_mask(f_best_alg_from_mask(a5_perm_alg)) + 1, 1);
+ chosenEncryptionAlgorithm := tr_BSSMAP_IE_ChosenEncryptionAlgorithm(chosen_alg);
+
+ if (g_pars.use_umts_aka and f_alg_supported_by_mask(a5_perm_alg, 4)) {
+ /* A5/4 is permitted, expecting kc128 to be present */
+ var OCT32 full_sha256 := f_calculate_HMAC_SHA256(g_pars.vec.ck & g_pars.vec.ik, '32'O, 32);
+ var OCT16 expect_kc128 := substr(full_sha256, 0, 16);
+ kC128 := tr_BSSMAP_IE_Kc128(expect_kc128);
+ } else {
+ kC128 := omit
+ }
+}
+
function f_mm_common() runs on BSC_ConnHdlr
{
f_mm_auth();
if (g_pars.ran_is_geran) {
if (g_pars.net.expect_ciph) {
- var OCT1 a5_net := f_alg_mask_from_cm(g_pars.cm2, g_pars.cm3);
- var OCT1 a5_intersect := g_pars.net.kc_support and4b a5_net;
- var boolean has_a54 := f_alg_supported_by_mask(a5_intersect, 4);
+ var template BSSMAP_IE_EncryptionInformation encryptionInformation;
+ var template BSSMAP_IE_ChosenEncryptionAlgorithm chosenEncryptionAlgorithm;
+ var template BSSMAP_IE_KC128 kC128;
+ var OCT1 a5_perm_alg;
+ f_get_expected_encryption(encryptionInformation, chosenEncryptionAlgorithm, kC128, a5_perm_alg);
var PDU_BSSAP pdu;
+ var template PDU_BSSAP expect_ciph_mode_cmd := tr_BSSMAP_CipherModeCmd2(encryptionInformation, kC128);
alt {
- [] BSSAP.receive(tr_BSSMAP_CipherModeCmd(a5_intersect, g_pars.vec.kc)) -> value pdu {
- var PDU_BSSMAP_CipherModeCommand ciphmodcmd := pdu.pdu.bssmap.cipherModeCommand;
- if (g_pars.use_umts_aka and has_a54) {
- var OCT32 fulloutput := f_calculate_HMAC_SHA256(g_pars.vec.ck & g_pars.vec.ik, '32'O, 32);
- var OCT16 kc128 := substr(fulloutput, 0, 16);
- if (not ispresent(ciphmodcmd.kC128)) {
- setverdict(fail, "kc128 missing in CiphModCmd");
- mtc.stop;
- }
- if (ciphmodcmd.kC128.kC128_Value != kc128) {
- setverdict(fail, "kc128 wrong in CiphModCmd?!", kc128);
- mtc.stop;
- }
- } else {
- if (ispresent(ciphmodcmd.kC128)) {
- setverdict(fail, "kc128 present in CiphModCmd, but should not exist!");
- mtc.stop;
- }
- }
-
- var OCT1 a5_chosen := f_best_alg_from_mask(a5_intersect);
+ [] BSSAP.receive(expect_ciph_mode_cmd) -> value pdu {
+ var OCT1 a5_chosen := f_best_alg_from_mask(a5_perm_alg);
var integer a5_nr := f_alg_from_mask(a5_chosen);
BSSAP.send(ts_BSSMAP_CipherModeCompl(int2oct(a5_nr+1, 1)));
}
- [] BSSAP.receive(tr_BSSMAP_CipherModeCmd(?, g_pars.vec.kc)) {
- setverdict(fail, "Wrong ciphering algorithm mask in CiphModCmd");
+ [] BSSAP.receive(tr_BSSMAP_CipherModeCmd2) -> value pdu {
+ log("Error: Ciphering Mode Command with unexpected content. Expected: ",
+ expect_ciph_mode_cmd, " got: ", pdu);
+ setverdict(fail, "Ciphering Mode Command with unexpected content.");
mtc.stop;
}
[] BSSAP.receive(tr_BSSMAP_ClassmarkRequest) {
--
To view, visit https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/24758
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Gerrit-Project: osmo-ttcn3-hacks
Gerrit-Branch: master
Gerrit-Change-Id: I1f775889fb801d441ea6c8b0f0c34718b814c09e
Gerrit-Change-Number: 24758
Gerrit-PatchSet: 1
Gerrit-Owner: neels <nhofmeyr at sysmocom.de>
Gerrit-MessageType: newchange
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