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-rw-r--r--src/libfilter/bsc_msg_filter.c398
1 files changed, 398 insertions, 0 deletions
diff --git a/src/libfilter/bsc_msg_filter.c b/src/libfilter/bsc_msg_filter.c
new file mode 100644
index 000000000..115d376cb
--- /dev/null
+++ b/src/libfilter/bsc_msg_filter.c
@@ -0,0 +1,398 @@
+/*
+ * 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);
+}
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