diff options
Diffstat (limited to 'src/osmo-bts-sysmo/l1_if.c')
| -rw-r--r-- | src/osmo-bts-sysmo/l1_if.c | 52 |
1 files changed, 47 insertions, 5 deletions
diff --git a/src/osmo-bts-sysmo/l1_if.c b/src/osmo-bts-sysmo/l1_if.c index 1c46ecfa..02d930e9 100644 --- a/src/osmo-bts-sysmo/l1_if.c +++ b/src/osmo-bts-sysmo/l1_if.c @@ -301,6 +301,37 @@ get_lapdm_chan_by_hl2(struct gsm_bts_trx *trx, uint32_t hLayer2) return &lchan->lapdm_ch; } +enum lchan_ciph_state { + LCHAN_CIPH_NONE, + LCHAN_CIPH_RX_REQ, + LCHAN_CIPH_RX_CONF, + LCHAN_CIPH_TXRX_REQ, + LCHAN_CIPH_TXRX_CONF, +}; + +/* check if the message is a GSM48_MT_RR_CIPH_M_CMD, and if yes, enable + * uni-directional de-cryption on the uplink. We need this ugly layering + * violation as we have no way of passing down L3 metadata (RSL CIPHERING CMD) + * to this point in L1 */ +static int check_for_ciph_cmd(struct femtol1_hdl *fl1h, + struct msgb *msg, struct gsm_lchan *lchan) +{ + /* First byte (Address Field) of LAPDm header) */ + if (msg->data[0] != 0x03) + return 0; + /* First byte (protocol discriminator) of RR */ + if ((msg->data[3] & 0xF) != GSM48_PDISC_RR) + return 0; + /* 2nd byte (msg type) of RR */ + if ((msg->data[4] & 0x3F) != GSM48_MT_RR_CIPH_M_CMD) + return 0; + + lchan->ciph_state = LCHAN_CIPH_RX_REQ; + l1if_enable_ciphering(fl1h, lchan, 0); + + return 1; +} + static const uint8_t fill_frame[GSM_MACBLOCK_LEN] = { 0x01, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, @@ -316,7 +347,6 @@ static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1, struct msgb *resp_msg; GsmL1_PhDataReq_t *data_req; GsmL1_MsgUnitParam_t *msu_param; - struct lapdm_channel *lc; struct lapdm_entity *le; struct gsm_lchan *lchan; struct gsm_time g_time; @@ -424,13 +454,15 @@ static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1, break; case GsmL1_Sapi_Sdcch: /* resolve the L2 entity using rts_ind->hLayer2 */ - lc = get_lapdm_chan_by_hl2(trx, rts_ind->hLayer2); - le = &lc->lapdm_dcch; + lchan = l1if_hLayer2_to_lchan(trx, rts_ind->hLayer2); + le = &lchan->lapdm_ch.lapdm_dcch; rc = lapdm_phsap_dequeue_prim(le, &pp); if (rc < 0) memcpy(msu_param->u8Buffer, fill_frame, GSM_MACBLOCK_LEN); else { memcpy(msu_param->u8Buffer, pp.oph.msg->data, GSM_MACBLOCK_LEN); + /* check if it is a RR CIPH MODE CMD. if yes, enable RX ciphering */ + check_for_ciph_cmd(fl1, pp.oph.msg, lchan); msgb_free(pp.oph.msg); } break; @@ -458,13 +490,15 @@ static int handle_ph_readytosend_ind(struct femtol1_hdl *fl1, case GsmL1_Sapi_FacchF: case GsmL1_Sapi_FacchH: /* resolve the L2 entity using rts_ind->hLayer2 */ - lc = get_lapdm_chan_by_hl2(trx, rts_ind->hLayer2); - le = &lc->lapdm_dcch; + lchan = l1if_hLayer2_to_lchan(trx, rts_ind->hLayer2); + le = &lchan->lapdm_ch.lapdm_dcch; rc = lapdm_phsap_dequeue_prim(le, &pp); if (rc < 0) goto empty_frame; else { memcpy(msu_param->u8Buffer, pp.oph.msg->data, GSM_MACBLOCK_LEN); + /* check if it is a RR CIPH MODE CMD. if yes, enable RX ciphering */ + check_for_ciph_cmd(fl1, pp.oph.msg, lchan); msgb_free(pp.oph.msg); } break; @@ -585,6 +619,14 @@ static int handle_ph_data_ind(struct femtol1_hdl *fl1, GsmL1_PhDataInd_t *data_i case GsmL1_Sapi_Sdcch: case GsmL1_Sapi_FacchF: case GsmL1_Sapi_FacchH: + /* if this is the first valid message after enabling Rx + * decryption, we have to enable Tx encryption */ + if (lchan->ciph_state == LCHAN_CIPH_RX_REQ || + lchan->ciph_state == LCHAN_CIPH_RX_CONF) { + l1if_enable_ciphering(fl1, lchan, 1); + lchan->ciph_state = LCHAN_CIPH_TXRX_REQ; + } + /* SDCCH, SACCH and FACCH all go to LAPDm */ le = le_by_l1_sapi(&lchan->lapdm_ch, data_ind->sapi); /* allocate and fill LAPDm primitive */ |