| /* |
| * Access filtering |
| */ |
| /* |
| * (C) 2010-2015 by Holger Hans Peter Freyther <zecke@selfish.org> |
| * (C) 2010-2012 by On-Waves |
| * All Rights Reserved |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU Affero General Public License as published by |
| * the Free Software Foundation; either version 3 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Affero General Public License for more details. |
| * |
| * You should have received a copy of the GNU Affero General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| * |
| */ |
| |
| #include <openbsc/bsc_msg_filter.h> |
| |
| #include <openbsc/bsc_nat.h> |
| #include <openbsc/bsc_msc.h> |
| #include <openbsc/gsm_data.h> |
| #include <openbsc/debug.h> |
| #include <openbsc/ipaccess.h> |
| |
| #include <osmocom/core/talloc.h> |
| #include <osmocom/gsm/gsm0808.h> |
| |
| #include <osmocom/gsm/protocol/gsm_08_08.h> |
| #include <osmocom/gsm/protocol/gsm_04_11.h> |
| |
| int bsc_filter_barr_find(struct rb_root *root, const char *imsi, int *cm, int *lu) |
| { |
| struct bsc_filter_barr_entry *n; |
| n = rb_entry(root->rb_node, struct bsc_filter_barr_entry, node); |
| |
| while (n) { |
| int rc = strcmp(imsi, n->imsi); |
| if (rc == 0) { |
| *cm = n->cm_reject_cause; |
| *lu = n->lu_reject_cause; |
| return 1; |
| } |
| |
| n = rb_entry( |
| (rc < 0) ? n->node.rb_left : n->node.rb_right, |
| struct bsc_filter_barr_entry, node); |
| }; |
| |
| return 0; |
| } |
| |
| static int insert_barr_node(struct bsc_filter_barr_entry *entry, struct rb_root *root) |
| { |
| struct rb_node **new = &root->rb_node, *parent = NULL; |
| |
| while (*new) { |
| int rc; |
| struct bsc_filter_barr_entry *this; |
| this = rb_entry(*new, struct bsc_filter_barr_entry, node); |
| parent = *new; |
| |
| rc = strcmp(entry->imsi, this->imsi); |
| if (rc < 0) |
| new = &((*new)->rb_left); |
| else if (rc > 0) |
| new = &((*new)->rb_right); |
| else { |
| LOGP(DFILTER, LOGL_ERROR, |
| "Duplicate entry for IMSI(%s)\n", entry->imsi); |
| talloc_free(entry); |
| return -1; |
| } |
| } |
| |
| rb_link_node(&entry->node, parent, new); |
| rb_insert_color(&entry->node, root); |
| return 0; |
| } |
| |
| int bsc_filter_barr_adapt(void *ctx, struct rb_root *root, |
| const struct osmo_config_list *list) |
| { |
| struct osmo_config_entry *cfg_entry; |
| int err = 0; |
| |
| /* free the old data */ |
| while (!RB_EMPTY_ROOT(root)) { |
| struct rb_node *node = rb_first(root); |
| rb_erase(node, root); |
| talloc_free(node); |
| } |
| |
| if (!list) |
| return 0; |
| |
| /* now adapt the new list */ |
| llist_for_each_entry(cfg_entry, &list->entry, list) { |
| struct bsc_filter_barr_entry *entry; |
| entry = talloc_zero(ctx, struct bsc_filter_barr_entry); |
| if (!entry) { |
| LOGP(DFILTER, LOGL_ERROR, |
| "Allocation of the barr entry failed.\n"); |
| continue; |
| } |
| |
| entry->imsi = talloc_strdup(entry, cfg_entry->mcc); |
| entry->cm_reject_cause = atoi(cfg_entry->mnc); |
| entry->lu_reject_cause = atoi(cfg_entry->option); |
| err |= insert_barr_node(entry, root); |
| } |
| |
| return err; |
| } |
| |
| |
| static int lst_check_deny(struct bsc_msg_acc_lst *lst, const char *mi_string, |
| int *cm_cause, int *lu_cause) |
| { |
| struct bsc_msg_acc_lst_entry *entry; |
| |
| llist_for_each_entry(entry, &lst->fltr_list, list) { |
| if (!entry->imsi_deny) |
| continue; |
| if (regexec(&entry->imsi_deny_re, mi_string, 0, NULL, 0) == 0) { |
| *cm_cause = entry->cm_reject_cause; |
| *lu_cause = entry->lu_reject_cause; |
| return 0; |
| } |
| } |
| |
| return 1; |
| } |
| |
| /* apply white/black list */ |
| static int auth_imsi(struct bsc_filter_request *req, |
| const char *imsi, |
| struct bsc_filter_reject_cause *cause) |
| { |
| /* |
| * Now apply blacklist/whitelist of the BSC and the NAT. |
| * 1.) Check the global IMSI barr list |
| * 2.) Allow directly if the IMSI is allowed at the BSC |
| * 3.) Reject if the IMSI is not allowed at the BSC |
| * 4.) Reject if the IMSI not allowed at the global level. |
| * 5.) Allow directly if the IMSI is allowed at the global level |
| */ |
| int cm, lu; |
| struct bsc_msg_acc_lst *nat_lst = NULL; |
| struct bsc_msg_acc_lst *bsc_lst = NULL; |
| |
| /* 1. global check for barred imsis */ |
| if (req->black_list && bsc_filter_barr_find(req->black_list, imsi, &cm, &lu)) { |
| cause->cm_reject_cause = cm; |
| cause->lu_reject_cause = lu; |
| LOGP(DFILTER, LOGL_DEBUG, |
| "Blocking subscriber IMSI %s with CM: %d LU: %d\n", |
| imsi, cm, lu); |
| return -4; |
| } |
| |
| |
| bsc_lst = bsc_msg_acc_lst_find(req->access_lists, req->local_lst_name); |
| nat_lst = bsc_msg_acc_lst_find(req->access_lists, req->global_lst_name); |
| |
| |
| if (bsc_lst) { |
| /* 2. BSC allow */ |
| if (bsc_msg_acc_lst_check_allow(bsc_lst, imsi) == 0) |
| return 1; |
| |
| /* 3. BSC deny */ |
| if (lst_check_deny(bsc_lst, imsi, &cm, &lu) == 0) { |
| LOGP(DFILTER, LOGL_ERROR, |
| "Filtering %s by imsi_deny on config nr: %d.\n", imsi, req->bsc_nr); |
| rate_ctr_inc(&bsc_lst->stats->ctr[ACC_LIST_LOCAL_FILTER]); |
| cause->cm_reject_cause = cm; |
| cause->lu_reject_cause = lu; |
| return -2; |
| } |
| |
| } |
| |
| /* 4. NAT deny */ |
| if (nat_lst) { |
| if (lst_check_deny(nat_lst, imsi, &cm, &lu) == 0) { |
| LOGP(DFILTER, LOGL_ERROR, |
| "Filtering %s global imsi_deny on bsc nr: %d.\n", imsi, req->bsc_nr); |
| rate_ctr_inc(&nat_lst->stats->ctr[ACC_LIST_GLOBAL_FILTER]); |
| cause->cm_reject_cause = cm; |
| cause->lu_reject_cause = lu; |
| return -3; |
| } |
| } |
| |
| return 1; |
| } |
| |
| static int _cr_check_loc_upd(void *ctx, |
| uint8_t *data, unsigned int length, |
| char **imsi) |
| { |
| uint8_t mi_type; |
| struct gsm48_loc_upd_req *lu; |
| char mi_string[GSM48_MI_SIZE]; |
| |
| if (length < sizeof(*lu)) { |
| LOGP(DFILTER, LOGL_ERROR, |
| "LU does not fit. Length is %d \n", length); |
| return -1; |
| } |
| |
| lu = (struct gsm48_loc_upd_req *) data; |
| mi_type = lu->mi[0] & GSM_MI_TYPE_MASK; |
| |
| /* |
| * We can only deal with the IMSI. This will fail for a phone that |
| * will send the TMSI of a previous network to us. |
| */ |
| if (mi_type != GSM_MI_TYPE_IMSI) |
| return 0; |
| |
| gsm48_mi_to_string(mi_string, sizeof(mi_string), lu->mi, lu->mi_len); |
| *imsi = talloc_strdup(ctx, mi_string); |
| return 1; |
| } |
| |
| static int _cr_check_cm_serv_req(void *ctx, |
| uint8_t *data, unsigned int length, |
| int *con_type, char **imsi) |
| { |
| static const uint32_t classmark_offset = |
| offsetof(struct gsm48_service_request, classmark); |
| |
| char mi_string[GSM48_MI_SIZE]; |
| uint8_t mi_type; |
| int rc; |
| struct gsm48_service_request *req; |
| |
| /* unfortunately in Phase1 the classmark2 length is variable */ |
| |
| if (length < sizeof(*req)) { |
| LOGP(DFILTER, LOGL_ERROR, |
| "CM Serv Req does not fit. Length is %d\n", length); |
| return -1; |
| } |
| |
| req = (struct gsm48_service_request *) data; |
| if (req->cm_service_type == 0x8) |
| *con_type = FLT_CON_TYPE_SSA; |
| rc = gsm48_extract_mi((uint8_t *) &req->classmark, |
| length - classmark_offset, mi_string, &mi_type); |
| if (rc < 0) { |
| LOGP(DFILTER, LOGL_ERROR, "Failed to parse the classmark2/mi. error: %d\n", rc); |
| return -1; |
| } |
| |
| /* we have to let the TMSI or such pass */ |
| if (mi_type != GSM_MI_TYPE_IMSI) |
| return 0; |
| |
| *imsi = talloc_strdup(ctx, mi_string); |
| return 1; |
| } |
| |
| static int _cr_check_pag_resp(void *ctx, |
| uint8_t *data, unsigned int length, char **imsi) |
| { |
| struct gsm48_pag_resp *resp; |
| char mi_string[GSM48_MI_SIZE]; |
| uint8_t mi_type; |
| |
| if (length < sizeof(*resp)) { |
| LOGP(DFILTER, LOGL_ERROR, "PAG RESP does not fit. Length was %d.\n", length); |
| return -1; |
| } |
| |
| resp = (struct gsm48_pag_resp *) data; |
| if (gsm48_paging_extract_mi(resp, length, mi_string, &mi_type) < 0) { |
| LOGP(DFILTER, LOGL_ERROR, "Failed to extract the MI.\n"); |
| return -1; |
| } |
| |
| /* we need to let it pass for now */ |
| if (mi_type != GSM_MI_TYPE_IMSI) |
| return 0; |
| |
| *imsi = talloc_strdup(ctx, mi_string); |
| return 1; |
| } |
| |
| static int _dt_check_id_resp(struct bsc_filter_request *req, |
| uint8_t *data, unsigned int length, |
| struct bsc_filter_state *state, |
| struct bsc_filter_reject_cause *cause) |
| { |
| char mi_string[GSM48_MI_SIZE]; |
| uint8_t mi_type; |
| |
| if (length < 2) { |
| LOGP(DFILTER, LOGL_ERROR, "mi does not fit.\n"); |
| return -1; |
| } |
| |
| if (data[0] < length - 1) { |
| LOGP(DFILTER, LOGL_ERROR, "mi length too big.\n"); |
| return -2; |
| } |
| |
| mi_type = data[1] & GSM_MI_TYPE_MASK; |
| gsm48_mi_to_string(mi_string, sizeof(mi_string), &data[1], data[0]); |
| |
| if (mi_type != GSM_MI_TYPE_IMSI) |
| return 0; |
| |
| state->imsi_checked = 1; |
| state->imsi = talloc_strdup(req->ctx, mi_string); |
| return auth_imsi(req, mi_string, cause); |
| } |
| |
| |
| /* Filter out CR data... */ |
| int bsc_msg_filter_initial(struct gsm48_hdr *hdr48, size_t hdr48_len, |
| struct bsc_filter_request *req, |
| int *con_type, |
| char **imsi, struct bsc_filter_reject_cause *cause) |
| { |
| int ret = 0; |
| uint8_t msg_type, proto; |
| |
| *con_type = FLT_CON_TYPE_NONE; |
| cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED; |
| cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED; |
| *imsi = NULL; |
| |
| proto = gsm48_hdr_pdisc(hdr48); |
| msg_type = gsm48_hdr_msg_type(hdr48); |
| if (proto == GSM48_PDISC_MM && |
| msg_type == GSM48_MT_MM_LOC_UPD_REQUEST) { |
| *con_type = FLT_CON_TYPE_LU; |
| ret = _cr_check_loc_upd(req->ctx, &hdr48->data[0], |
| hdr48_len - sizeof(*hdr48), imsi); |
| } else if (proto == GSM48_PDISC_MM && |
| msg_type == GSM48_MT_MM_CM_SERV_REQ) { |
| *con_type = FLT_CON_TYPE_CM_SERV_REQ; |
| ret = _cr_check_cm_serv_req(req->ctx, &hdr48->data[0], |
| hdr48_len - sizeof(*hdr48), |
| con_type, imsi); |
| } else if (proto == GSM48_PDISC_RR && |
| msg_type == GSM48_MT_RR_PAG_RESP) { |
| *con_type = FLT_CON_TYPE_PAG_RESP; |
| ret = _cr_check_pag_resp(req->ctx, &hdr48->data[0], |
| hdr48_len - sizeof(*hdr48), imsi); |
| } else { |
| /* We only want to filter the above, let other things pass */ |
| *con_type = FLT_CON_TYPE_OTHER; |
| return 0; |
| } |
| |
| /* check if we are done */ |
| if (ret != 1) |
| return ret; |
| |
| /* the memory allocation failed */ |
| if (!*imsi) |
| return -1; |
| |
| /* now check the imsi */ |
| return auth_imsi(req, *imsi, cause); |
| } |
| |
| int bsc_msg_filter_data(struct gsm48_hdr *hdr48, size_t len, |
| struct bsc_filter_request *req, |
| struct bsc_filter_state *state, |
| struct bsc_filter_reject_cause *cause) |
| { |
| uint8_t msg_type, proto; |
| |
| cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED; |
| cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED; |
| |
| if (state->imsi_checked) |
| return 0; |
| |
| proto = gsm48_hdr_pdisc(hdr48); |
| msg_type = gsm48_hdr_msg_type(hdr48); |
| if (proto != GSM48_PDISC_MM || msg_type != GSM48_MT_MM_ID_RESP) |
| return 0; |
| |
| return _dt_check_id_resp(req, &hdr48->data[0], |
| len - sizeof(*hdr48), state, cause); |
| } |