436 lines
11 KiB
C
436 lines
11 KiB
C
/*
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* Access filtering
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*/
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/*
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* (C) 2010-2012 by Holger Hans Peter Freyther <zecke@selfish.org>
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* (C) 2010-2012 by On-Waves
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <openbsc/bsc_nat.h>
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#include <openbsc/bsc_nat_sccp.h>
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#include <openbsc/bsc_msc.h>
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#include <openbsc/gsm_data.h>
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#include <openbsc/debug.h>
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#include <openbsc/ipaccess.h>
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#include <osmocom/core/linuxlist.h>
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#include <osmocom/core/talloc.h>
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#include <osmocom/gsm/gsm0808.h>
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#include <osmocom/gsm/protocol/gsm_08_08.h>
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#include <osmocom/gsm/protocol/gsm_04_11.h>
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#include <osmocom/sccp/sccp.h>
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int bsc_nat_barr_find(struct rb_root *root, const char *imsi, int *cm, int *lu)
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{
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struct bsc_nat_barr_entry *n;
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n = rb_entry(root->rb_node, struct bsc_nat_barr_entry, node);
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while (n) {
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int rc = strcmp(imsi, n->imsi);
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if (rc == 0) {
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*cm = n->cm_reject_cause;
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*lu = n->lu_reject_cause;
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return 1;
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}
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n = rb_entry(
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(rc < 0) ? n->node.rb_left : n->node.rb_right,
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struct bsc_nat_barr_entry, node);
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};
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return 0;
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}
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static int insert_barr_node(struct bsc_nat_barr_entry *entry, struct rb_root *root)
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{
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struct rb_node **new = &root->rb_node, *parent = NULL;
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while (*new) {
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int rc;
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struct bsc_nat_barr_entry *this;
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this = rb_entry(*new, struct bsc_nat_barr_entry, node);
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parent = *new;
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rc = strcmp(entry->imsi, this->imsi);
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if (rc < 0)
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new = &((*new)->rb_left);
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else if (rc > 0)
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new = &((*new)->rb_right);
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else {
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LOGP(DNAT, LOGL_ERROR,
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"Duplicate entry for IMSI(%s)\n", entry->imsi);
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talloc_free(entry);
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return -1;
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}
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}
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rb_link_node(&entry->node, parent, new);
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rb_insert_color(&entry->node, root);
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return 0;
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}
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int bsc_nat_barr_adapt(void *ctx, struct rb_root *root,
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const struct osmo_config_list *list)
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{
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struct osmo_config_entry *cfg_entry;
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int err = 0;
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/* free the old data */
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while (!RB_EMPTY_ROOT(root)) {
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struct rb_node *node = rb_first(root);
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rb_erase(node, root);
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talloc_free(node);
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}
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if (!list)
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return 0;
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/* now adapt the new list */
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llist_for_each_entry(cfg_entry, &list->entry, list) {
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struct bsc_nat_barr_entry *entry;
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entry = talloc_zero(ctx, struct bsc_nat_barr_entry);
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if (!entry) {
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LOGP(DNAT, LOGL_ERROR,
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"Allocation of the barr entry failed.\n");
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continue;
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}
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entry->imsi = talloc_strdup(entry, cfg_entry->mcc);
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entry->cm_reject_cause = atoi(cfg_entry->mnc);
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entry->lu_reject_cause = atoi(cfg_entry->option);
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err |= insert_barr_node(entry, root);
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}
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return err;
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}
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static int lst_check_deny(struct bsc_nat_acc_lst *lst, const char *mi_string)
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{
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struct bsc_nat_acc_lst_entry *entry;
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llist_for_each_entry(entry, &lst->fltr_list, list) {
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if (!entry->imsi_deny)
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continue;
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if (regexec(&entry->imsi_deny_re, mi_string, 0, NULL, 0) == 0)
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return 0;
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}
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return 1;
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}
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/* apply white/black list */
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static int auth_imsi(struct bsc_connection *bsc, const char *imsi,
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struct bsc_nat_reject_cause *cause)
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{
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/*
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* Now apply blacklist/whitelist of the BSC and the NAT.
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* 1.) Check the global IMSI barr list
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* 2.) Allow directly if the IMSI is allowed at the BSC
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* 3.) Reject if the IMSI is not allowed at the BSC
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* 4.) Reject if the IMSI not allowed at the global level.
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* 5.) Allow directly if the IMSI is allowed at the global level
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*/
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int cm, lu;
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struct bsc_nat_acc_lst *nat_lst = NULL;
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struct bsc_nat_acc_lst *bsc_lst = NULL;
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/* 1. global check for barred imsis */
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if (bsc_nat_barr_find(&bsc->nat->imsi_black_list, imsi, &cm, &lu)) {
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cause->cm_reject_cause = cm;
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cause->lu_reject_cause = lu;
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LOGP(DNAT, LOGL_DEBUG,
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"Blocking subscriber IMSI %s with CM: %d LU: %d\n",
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imsi, cm, lu);
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return -1;
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}
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bsc_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->cfg->acc_lst_name);
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nat_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->nat->acc_lst_name);
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if (bsc_lst) {
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/* 2. BSC allow */
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if (bsc_nat_lst_check_allow(bsc_lst, imsi) == 0)
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return 1;
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/* 3. BSC deny */
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if (lst_check_deny(bsc_lst, imsi) == 0) {
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LOGP(DNAT, LOGL_ERROR,
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"Filtering %s by imsi_deny on bsc nr: %d.\n", imsi, bsc->cfg->nr);
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rate_ctr_inc(&bsc_lst->stats->ctr[ACC_LIST_BSC_FILTER]);
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return -2;
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}
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}
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/* 4. NAT deny */
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if (nat_lst) {
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if (lst_check_deny(nat_lst, imsi) == 0) {
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LOGP(DNAT, LOGL_ERROR,
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"Filtering %s by nat imsi_deny on bsc nr: %d.\n", imsi, bsc->cfg->nr);
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rate_ctr_inc(&nat_lst->stats->ctr[ACC_LIST_NAT_FILTER]);
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return -3;
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}
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}
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return 1;
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}
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static int _cr_check_loc_upd(struct bsc_connection *bsc,
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uint8_t *data, unsigned int length,
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char **imsi)
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{
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uint8_t mi_type;
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struct gsm48_loc_upd_req *lu;
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char mi_string[GSM48_MI_SIZE];
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if (length < sizeof(*lu)) {
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LOGP(DNAT, LOGL_ERROR,
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"LU does not fit. Length is %d \n", length);
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return -1;
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}
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lu = (struct gsm48_loc_upd_req *) data;
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mi_type = lu->mi[0] & GSM_MI_TYPE_MASK;
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/*
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* We can only deal with the IMSI. This will fail for a phone that
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* will send the TMSI of a previous network to us.
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*/
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if (mi_type != GSM_MI_TYPE_IMSI)
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return 0;
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gsm48_mi_to_string(mi_string, sizeof(mi_string), lu->mi, lu->mi_len);
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*imsi = talloc_strdup(bsc, mi_string);
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return 1;
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}
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static int _cr_check_cm_serv_req(struct bsc_connection *bsc,
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uint8_t *data, unsigned int length,
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int *con_type, char **imsi)
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{
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static const uint32_t classmark_offset =
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offsetof(struct gsm48_service_request, classmark);
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char mi_string[GSM48_MI_SIZE];
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uint8_t mi_type;
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int rc;
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struct gsm48_service_request *req;
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/* unfortunately in Phase1 the classmark2 length is variable */
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if (length < sizeof(*req)) {
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LOGP(DNAT, LOGL_ERROR,
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"CM Serv Req does not fit. Length is %d\n", length);
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return -1;
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}
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req = (struct gsm48_service_request *) data;
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if (req->cm_service_type == 0x8)
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*con_type = NAT_CON_TYPE_SSA;
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rc = gsm48_extract_mi((uint8_t *) &req->classmark,
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length - classmark_offset, mi_string, &mi_type);
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if (rc < 0) {
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LOGP(DNAT, LOGL_ERROR, "Failed to parse the classmark2/mi. error: %d\n", rc);
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return -1;
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}
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/* we have to let the TMSI or such pass */
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if (mi_type != GSM_MI_TYPE_IMSI)
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return 0;
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*imsi = talloc_strdup(bsc, mi_string);
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return 1;
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}
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static int _cr_check_pag_resp(struct bsc_connection *bsc,
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uint8_t *data, unsigned int length, char **imsi)
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{
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struct gsm48_pag_resp *resp;
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char mi_string[GSM48_MI_SIZE];
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uint8_t mi_type;
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if (length < sizeof(*resp)) {
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LOGP(DNAT, LOGL_ERROR, "PAG RESP does not fit. Length was %d.\n", length);
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return -1;
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}
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resp = (struct gsm48_pag_resp *) data;
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if (gsm48_paging_extract_mi(resp, length, mi_string, &mi_type) < 0) {
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LOGP(DNAT, LOGL_ERROR, "Failed to extract the MI.\n");
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return -1;
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}
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/* we need to let it pass for now */
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if (mi_type != GSM_MI_TYPE_IMSI)
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return 0;
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*imsi = talloc_strdup(bsc, mi_string);
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return 1;
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}
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static int _dt_check_id_resp(struct bsc_connection *bsc,
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uint8_t *data, unsigned int length,
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struct sccp_connections *con,
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struct bsc_nat_reject_cause *cause)
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{
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char mi_string[GSM48_MI_SIZE];
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uint8_t mi_type;
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if (length < 2) {
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LOGP(DNAT, LOGL_ERROR, "mi does not fit.\n");
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return -1;
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}
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if (data[0] < length - 1) {
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LOGP(DNAT, LOGL_ERROR, "mi length too big.\n");
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return -2;
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}
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mi_type = data[1] & GSM_MI_TYPE_MASK;
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gsm48_mi_to_string(mi_string, sizeof(mi_string), &data[1], data[0]);
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if (mi_type != GSM_MI_TYPE_IMSI)
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return 0;
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con->imsi_checked = 1;
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con->imsi = talloc_strdup(con, mi_string);
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return auth_imsi(bsc, mi_string, cause);
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}
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/* Filter out CR data... */
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int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
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struct bsc_nat_parsed *parsed, int *con_type,
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char **imsi, struct bsc_nat_reject_cause *cause)
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{
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struct tlv_parsed tp;
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struct gsm48_hdr *hdr48;
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int hdr48_len;
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int len, ret = 0;
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uint8_t msg_type, proto;
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*con_type = NAT_CON_TYPE_NONE;
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cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
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cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
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*imsi = NULL;
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if (parsed->gsm_type != BSS_MAP_MSG_COMPLETE_LAYER_3) {
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LOGP(DNAT, LOGL_ERROR,
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"Rejecting CR message due wrong GSM Type %d\n", parsed->gsm_type);
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return -1;
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}
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/* the parsed has had some basic l3 length check */
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len = msg->l3h[1];
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if (msgb_l3len(msg) - 3 < len) {
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LOGP(DNAT, LOGL_ERROR,
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"The CR Data has not enough space...\n");
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return -1;
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}
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msg->l4h = &msg->l3h[3];
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len -= 1;
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tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h, len, 0, 0);
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if (!TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_INFORMATION)) {
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LOGP(DNAT, LOGL_ERROR, "CR Data does not contain layer3 information.\n");
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return -1;
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}
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hdr48_len = TLVP_LEN(&tp, GSM0808_IE_LAYER_3_INFORMATION);
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if (hdr48_len < sizeof(*hdr48)) {
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LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
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return -1;
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}
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hdr48 = (struct gsm48_hdr *) TLVP_VAL(&tp, GSM0808_IE_LAYER_3_INFORMATION);
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proto = hdr48->proto_discr & 0x0f;
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msg_type = hdr48->msg_type & 0xbf;
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if (proto == GSM48_PDISC_MM &&
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msg_type == GSM48_MT_MM_LOC_UPD_REQUEST) {
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*con_type = NAT_CON_TYPE_LU;
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ret = _cr_check_loc_upd(bsc, &hdr48->data[0],
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hdr48_len - sizeof(*hdr48), imsi);
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} else if (proto == GSM48_PDISC_MM &&
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msg_type == GSM48_MT_MM_CM_SERV_REQ) {
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*con_type = NAT_CON_TYPE_CM_SERV_REQ;
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ret = _cr_check_cm_serv_req(bsc, &hdr48->data[0],
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hdr48_len - sizeof(*hdr48),
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con_type, imsi);
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} else if (proto == GSM48_PDISC_RR &&
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msg_type == GSM48_MT_RR_PAG_RESP) {
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*con_type = NAT_CON_TYPE_PAG_RESP;
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ret = _cr_check_pag_resp(bsc, &hdr48->data[0],
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hdr48_len - sizeof(*hdr48), imsi);
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} else {
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/* We only want to filter the above, let other things pass */
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*con_type = NAT_CON_TYPE_OTHER;
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return 0;
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}
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/* check if we are done */
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if (ret != 1)
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return ret;
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/* the memory allocation failed */
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if (!*imsi)
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return -1;
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/* now check the imsi */
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return auth_imsi(bsc, *imsi, cause);
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}
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int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
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struct sccp_connections *con, struct bsc_nat_parsed *parsed,
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struct bsc_nat_reject_cause *cause)
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{
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uint32_t len;
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uint8_t msg_type, proto;
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struct gsm48_hdr *hdr48;
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cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
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cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
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if (con->imsi_checked)
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return 0;
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/* only care about DTAP messages */
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if (parsed->bssap != BSSAP_MSG_DTAP)
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return 0;
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hdr48 = bsc_unpack_dtap(parsed, msg, &len);
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if (!hdr48)
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return -1;
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proto = hdr48->proto_discr & 0x0f;
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msg_type = hdr48->msg_type & 0xbf;
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if (proto != GSM48_PDISC_MM || msg_type != GSM48_MT_MM_ID_RESP)
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return 0;
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return _dt_check_id_resp(bsc, &hdr48->data[0],
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len - sizeof(*hdr48), con, cause);
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}
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