diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/osmo-bsc/osmo_bsc_bssap.c | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/src/osmo-bsc/osmo_bsc_bssap.c b/src/osmo-bsc/osmo_bsc_bssap.c index 051b74e60..4fd43aa9a 100644 --- a/src/osmo-bsc/osmo_bsc_bssap.c +++ b/src/osmo-bsc/osmo_bsc_bssap.c @@ -397,6 +397,10 @@ static int bssmap_handle_cipher_mode(struct osmo_bsc_sccp_con *conn, struct msgb *resp; int reject_cause = -1; int include_imeisv = 1; + uint8_t *enc_key; + uint16_t enc_key_len; + uint8_t enc_bits_bsc; + uint8_t enc_bits_msc; if (!conn->conn) { LOGP(DMSC, LOGL_ERROR, "No lchan/msc_data in cipher mode command.\n"); @@ -430,19 +434,38 @@ static int bssmap_handle_cipher_mode(struct osmo_bsc_sccp_con *conn, network = conn->conn->bts->network; data = TLVP_VAL(&tp, GSM0808_IE_ENCRYPTION_INFORMATION); + enc_bits_msc = data[0]; + enc_key = &data[1]; + enc_key_len = len - 1; if (TLVP_PRESENT(&tp, GSM0808_IE_CIPHER_RESPONSE_MODE)) include_imeisv = TLVP_VAL(&tp, GSM0808_IE_CIPHER_RESPONSE_MODE)[0] & 0x1; - if (network->a5_encryption == 0 && (data[0] & 0x1) == 0x1) { - gsm0808_cipher_mode(conn->conn, 0, NULL, 0, include_imeisv); - } else if (network->a5_encryption != 0 && (data[0] & 0x2) == 0x2) { - gsm0808_cipher_mode(conn->conn, 1, &data[1], len - 1, include_imeisv); - } else { - LOGP(DMSC, LOGL_ERROR, "Can not select encryption...\n"); + /* FIXME: match up the list of permitted ciphering algorithms received from the MSC with a list + * of ciphering algorithms configured for this BSC (the config of more than one is TODO). Finally + * pick one of the remaining options. */ + + /* Identical to the GSM0808_IE_ENCRYPTION_INFORMATION above: + * a5_encryption == 0 --> 0x01 + * a5_encryption == 1 --> 0x02 + * a5_encryption == 2 --> 0x04 ... */ + enc_bits_bsc = 1 << network->a5_encryption; + enc_bits_msc = data[0]; + + if (!(enc_bits_msc & enc_bits_bsc)) { + LOGP(DMSC, LOGL_ERROR, "MSC does not permit A5/%d (permitted algorithms mask: 0x%x)\n", + network->a5_encryption, enc_bits_msc); + reject_cause = GSM0808_CAUSE_CIPHERING_ALGORITHM_NOT_SUPPORTED; goto reject; } + /* To complete the confusion, gsm0808_cipher_mode again expects the encryption as a number + * from 0 to 7. */ + if (gsm0808_cipher_mode(conn->conn, network->a5_encryption, enc_key, enc_key_len, + include_imeisv)) { + reject_cause = GSM0808_CAUSE_PROTOCOL_ERROR_BETWEEN_BSS_AND_MSC; + goto reject; + } return 0; reject: |