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authorVadim Yanitskiy <vyanitskiy@sysmocom.de>2020-08-31 19:10:39 +0700
committerlaforge <laforge@osmocom.org>2020-09-18 08:41:57 +0000
commitecaf5faa7994379319980313b5ce15d3c12db86e (patch)
tree35545ad24ceff1fc7a84a1be29124819a526c315
parent7da6ace594cf24ee0015b0c0ec5404ccdbe59b6c (diff)
gsm0808: fix: do not encode invalid encryption algorithmHEADmaster
According to 3GPP TS 48.008, section 3.2.2.44, the Chosen Encryption Algorithm IE, which may be included in the following messages: - 3.2.1.2 ASSIGNMENT COMPLETE - 3.2.1.8 HANDOVER REQUEST - 3.2.1.10 HANDOVER REQUEST ACKNOWLEDGE - 3.2.1.12 HANDOVER COMPLETE - 3.2.1.25 HANDOVER PERFORMED - 3.2.1.31 CIPHER MODE COMPLETE is coded as follows: 0000 0001 No encryption used 0000 0010 GSM A5/1 0000 0011 GSM A5/2 0000 0100 GSM A5/3 0000 0101 GSM A5/4 0000 0110 GSM A5/5 0000 0111 GSM A5/6 0000 1000 GSM A5/7 basically A5/X => X + 1. All other values are Reserved for future international use. As can be seen, value 0x00 is RFU. Passing this value to some encoding functions would result in a PDU with this IE omitted. Although, some functions would still encode Chosen Encryption Algorithm IE with this RFU value. Let's ensure that all functions behave consistently. Change-Id: If10e433a8174eabe6aa6d2c2937bf9cf5d14d7c9
-rw-r--r--src/gsm/gsm0808.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/src/gsm/gsm0808.c b/src/gsm/gsm0808.c
index 85f5cfc9..53220617 100644
--- a/src/gsm/gsm0808.c
+++ b/src/gsm/gsm0808.c
@@ -283,8 +283,9 @@ struct msgb *gsm0808_create_cipher_complete(struct msgb *layer3, uint8_t alg_id)
msgb_l3len(layer3), layer3->l3h);
}
- /* and the optional BSS message */
- msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, alg_id);
+ /* Optional Chosen Encryption Algorithm IE */
+ if (alg_id > 0)
+ msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, alg_id);
/* pre-pend the header */
msg->l3h = msgb_tv_push(msg, BSSAP_MSG_BSS_MANAGEMENT, msgb_length(msg));
@@ -603,7 +604,8 @@ struct msgb *gsm0808_create_ass_compl2(uint8_t rr_cause, uint8_t chosen_channel,
msgb_tv_put(msg, GSM0808_IE_CHOSEN_CHANNEL, chosen_channel);
/* write chosen encryption algorithm 3.2.2.44 */
- msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, encr_alg_id);
+ if (encr_alg_id > 0)
+ msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, encr_alg_id);
/* write circuit pool 3.2.2.45 */
/* write speech version chosen: 3.2.2.51 when BTS picked it */
@@ -964,7 +966,7 @@ struct msgb *gsm0808_create_handover_request(const struct gsm0808_handover_reque
}
/* Chosen Encryption Algorithm (Serving) 3.2.2.44 */
- if (params->chosen_encryption_algorithm_serving)
+ if (params->chosen_encryption_algorithm_serving > 0)
msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, params->chosen_encryption_algorithm_serving);
/* Old BSS to New BSS Information 3.2.2.58 */
@@ -1027,7 +1029,7 @@ struct msgb *gsm0808_create_handover_request_ack2(const struct gsm0808_handover_
if (params->chosen_channel_present)
msgb_tv_put(msg, GSM0808_IE_CHOSEN_CHANNEL, params->chosen_channel);
- if (params->chosen_encr_alg)
+ if (params->chosen_encr_alg > 0)
msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, params->chosen_encr_alg);
if (params->chosen_speech_version != 0)
@@ -1157,7 +1159,7 @@ struct msgb *gsm0808_create_handover_complete(const struct gsm0808_handover_comp
gsm0808_enc_speech_codec_list(msg, &params->codec_list_bss_supported);
/* Chosen Encryption Algorithm 3.2.2.44 */
- if (params->chosen_encr_alg_present)
+ if (params->chosen_encr_alg_present && params->chosen_encr_alg > 0)
msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, params->chosen_encr_alg);
/* LCLS-BSS-Status 3.2.2.119 */
@@ -1225,7 +1227,7 @@ struct msgb *gsm0808_create_handover_performed(const struct gsm0808_handover_per
msgb_tv_put(msg, GSM0808_IE_CHOSEN_CHANNEL, params->chosen_channel);
/* Chosen Encryption Algorithm 3.2.2.44 */
- if (params->chosen_encr_alg_present)
+ if (params->chosen_encr_alg_present && params->chosen_encr_alg > 0)
msgb_tv_put(msg, GSM0808_IE_CHOSEN_ENCR_ALG, params->chosen_encr_alg);
/* Speech Version (chosen) 3.2.2.51 */