nat: Move the IMSI/TMSI filtering to a new and dedicated file

Move all routines related to filtering to a separate file.
This commit is contained in:
Holger Hans Peter Freyther 2012-12-17 13:32:53 +01:00
parent 6fbd864a65
commit adc2e87372
4 changed files with 323 additions and 282 deletions

View File

@ -6,7 +6,8 @@ bin_PROGRAMS = osmo-bsc_nat
osmo_bsc_nat_SOURCES = bsc_filter.c bsc_mgcp_utils.c bsc_nat.c bsc_nat_utils.c \
bsc_nat_vty.c bsc_sccp.c bsc_ussd.c bsc_nat_ctrl.c bsc_nat_rewrite.c
bsc_nat_vty.c bsc_sccp.c bsc_ussd.c bsc_nat_ctrl.c \
bsc_nat_rewrite.c bsc_nat_filter.c
osmo_bsc_nat_LDADD = $(top_builddir)/src/libcommon/libcommon.a \
$(top_builddir)/src/libmgcp/libmgcp.a \
$(top_builddir)/src/libbsc/libbsc.a \

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@ -0,0 +1,320 @@
/*
* Access filtering
*/
/*
* (C) 2010-2011 by Holger Hans Peter Freyther <zecke@selfish.org>
* (C) 2010-2011 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_nat.h>
#include <openbsc/bsc_nat_sccp.h>
#include <openbsc/bsc_msc.h>
#include <openbsc/gsm_data.h>
#include <openbsc/debug.h>
#include <openbsc/ipaccess.h>
#include <osmocom/core/linuxlist.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>
#include <osmocom/sccp/sccp.h>
static int lst_check_deny(struct bsc_nat_acc_lst *lst, const char *mi_string)
{
struct bsc_nat_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)
return 0;
}
return 1;
}
/* apply white/black list */
static int auth_imsi(struct bsc_connection *bsc, const char *mi_string)
{
/*
* Now apply blacklist/whitelist of the BSC and the NAT.
* 1.) Allow directly if the IMSI is allowed at the BSC
* 2.) Reject if the IMSI is not allowed at the BSC
* 3.) Reject if the IMSI not allowed at the global level.
* 4.) Allow directly if the IMSI is allowed at the global level
*/
struct bsc_nat_acc_lst *nat_lst = NULL;
struct bsc_nat_acc_lst *bsc_lst = NULL;
bsc_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->cfg->acc_lst_name);
nat_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->nat->acc_lst_name);
if (bsc_lst) {
/* 1. BSC allow */
if (bsc_nat_lst_check_allow(bsc_lst, mi_string) == 0)
return 1;
/* 2. BSC deny */
if (lst_check_deny(bsc_lst, mi_string) == 0) {
LOGP(DNAT, LOGL_ERROR,
"Filtering %s by imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
rate_ctr_inc(&bsc_lst->stats->ctr[ACC_LIST_BSC_FILTER]);
return -2;
}
}
/* 3. NAT deny */
if (nat_lst) {
if (lst_check_deny(nat_lst, mi_string) == 0) {
LOGP(DNAT, LOGL_ERROR,
"Filtering %s by nat imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
rate_ctr_inc(&nat_lst->stats->ctr[ACC_LIST_NAT_FILTER]);
return -3;
}
}
return 1;
}
static int _cr_check_loc_upd(struct bsc_connection *bsc,
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(DNAT, 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(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _cr_check_cm_serv_req(struct bsc_connection *bsc,
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(DNAT, 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 = NAT_CON_TYPE_SSA;
rc = gsm48_extract_mi((uint8_t *) &req->classmark,
length - classmark_offset, mi_string, &mi_type);
if (rc < 0) {
LOGP(DNAT, 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(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _cr_check_pag_resp(struct bsc_connection *bsc,
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(DNAT, 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(DNAT, 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(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _dt_check_id_resp(struct bsc_connection *bsc,
uint8_t *data, unsigned int length,
struct sccp_connections *con)
{
char mi_string[GSM48_MI_SIZE];
uint8_t mi_type;
int ret;
if (length < 2) {
LOGP(DNAT, LOGL_ERROR, "mi does not fit.\n");
return -1;
}
if (data[0] < length - 1) {
LOGP(DNAT, 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;
ret = auth_imsi(bsc, mi_string);
con->imsi_checked = 1;
con->imsi = talloc_strdup(con, mi_string);
return ret;
}
/* Filter out CR data... */
int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
struct bsc_nat_parsed *parsed, int *con_type,
char **imsi)
{
struct tlv_parsed tp;
struct gsm48_hdr *hdr48;
int hdr48_len;
int len;
uint8_t msg_type, proto;
*con_type = NAT_CON_TYPE_NONE;
*imsi = NULL;
if (parsed->gsm_type != BSS_MAP_MSG_COMPLETE_LAYER_3) {
LOGP(DNAT, LOGL_ERROR,
"Rejecting CR message due wrong GSM Type %d\n", parsed->gsm_type);
return -1;
}
/* the parsed has had some basic l3 length check */
len = msg->l3h[1];
if (msgb_l3len(msg) - 3 < len) {
LOGP(DNAT, LOGL_ERROR,
"The CR Data has not enough space...\n");
return -1;
}
msg->l4h = &msg->l3h[3];
len -= 1;
tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h, len, 0, 0);
if (!TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_INFORMATION)) {
LOGP(DNAT, LOGL_ERROR, "CR Data does not contain layer3 information.\n");
return -1;
}
hdr48_len = TLVP_LEN(&tp, GSM0808_IE_LAYER_3_INFORMATION);
if (hdr48_len < sizeof(*hdr48)) {
LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
return -1;
}
hdr48 = (struct gsm48_hdr *) TLVP_VAL(&tp, GSM0808_IE_LAYER_3_INFORMATION);
proto = hdr48->proto_discr & 0x0f;
msg_type = hdr48->msg_type & 0xbf;
if (proto == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_LOC_UPD_REQUEST) {
*con_type = NAT_CON_TYPE_LU;
return _cr_check_loc_upd(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
} else if (proto == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_CM_SERV_REQ) {
*con_type = NAT_CON_TYPE_CM_SERV_REQ;
return _cr_check_cm_serv_req(bsc, &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 = NAT_CON_TYPE_PAG_RESP;
return _cr_check_pag_resp(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
} else {
/* We only want to filter the above, let other things pass */
*con_type = NAT_CON_TYPE_OTHER;
return 0;
}
}
int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
struct sccp_connections *con, struct bsc_nat_parsed *parsed)
{
uint32_t len;
uint8_t msg_type, proto;
struct gsm48_hdr *hdr48;
if (con->imsi_checked)
return 0;
/* only care about DTAP messages */
if (parsed->bssap != BSSAP_MSG_DTAP)
return 0;
hdr48 = bsc_unpack_dtap(parsed, msg, &len);
if (!hdr48)
return -1;
proto = hdr48->proto_discr & 0x0f;
msg_type = hdr48->msg_type & 0xbf;
if (proto == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_ID_RESP) {
return _dt_check_id_resp(bsc, &hdr48->data[0], len - sizeof(*hdr48), con);
} else {
return 0;
}
}

View File

@ -374,259 +374,6 @@ int bsc_nat_lst_check_allow(struct bsc_nat_acc_lst *lst, const char *mi_string)
return 1;
}
static int lst_check_deny(struct bsc_nat_acc_lst *lst, const char *mi_string)
{
struct bsc_nat_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)
return 0;
}
return 1;
}
/* apply white/black list */
static int auth_imsi(struct bsc_connection *bsc, const char *mi_string)
{
/*
* Now apply blacklist/whitelist of the BSC and the NAT.
* 1.) Allow directly if the IMSI is allowed at the BSC
* 2.) Reject if the IMSI is not allowed at the BSC
* 3.) Reject if the IMSI not allowed at the global level.
* 4.) Allow directly if the IMSI is allowed at the global level
*/
struct bsc_nat_acc_lst *nat_lst = NULL;
struct bsc_nat_acc_lst *bsc_lst = NULL;
bsc_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->cfg->acc_lst_name);
nat_lst = bsc_nat_acc_lst_find(bsc->nat, bsc->nat->acc_lst_name);
if (bsc_lst) {
/* 1. BSC allow */
if (bsc_nat_lst_check_allow(bsc_lst, mi_string) == 0)
return 1;
/* 2. BSC deny */
if (lst_check_deny(bsc_lst, mi_string) == 0) {
LOGP(DNAT, LOGL_ERROR,
"Filtering %s by imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
rate_ctr_inc(&bsc_lst->stats->ctr[ACC_LIST_BSC_FILTER]);
return -2;
}
}
/* 3. NAT deny */
if (nat_lst) {
if (lst_check_deny(nat_lst, mi_string) == 0) {
LOGP(DNAT, LOGL_ERROR,
"Filtering %s by nat imsi_deny on bsc nr: %d.\n", mi_string, bsc->cfg->nr);
rate_ctr_inc(&nat_lst->stats->ctr[ACC_LIST_NAT_FILTER]);
return -3;
}
}
return 1;
}
static int _cr_check_loc_upd(struct bsc_connection *bsc,
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(DNAT, 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(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _cr_check_cm_serv_req(struct bsc_connection *bsc,
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(DNAT, 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 = NAT_CON_TYPE_SSA;
rc = gsm48_extract_mi((uint8_t *) &req->classmark,
length - classmark_offset, mi_string, &mi_type);
if (rc < 0) {
LOGP(DNAT, 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(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _cr_check_pag_resp(struct bsc_connection *bsc,
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(DNAT, 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(DNAT, 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(bsc, mi_string);
return auth_imsi(bsc, mi_string);
}
static int _dt_check_id_resp(struct bsc_connection *bsc,
uint8_t *data, unsigned int length,
struct sccp_connections *con)
{
char mi_string[GSM48_MI_SIZE];
uint8_t mi_type;
int ret;
if (length < 2) {
LOGP(DNAT, LOGL_ERROR, "mi does not fit.\n");
return -1;
}
if (data[0] < length - 1) {
LOGP(DNAT, 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;
ret = auth_imsi(bsc, mi_string);
con->imsi_checked = 1;
con->imsi = talloc_strdup(con, mi_string);
return ret;
}
/* Filter out CR data... */
int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
struct bsc_nat_parsed *parsed, int *con_type,
char **imsi)
{
struct tlv_parsed tp;
struct gsm48_hdr *hdr48;
int hdr48_len;
int len;
uint8_t msg_type, proto;
*con_type = NAT_CON_TYPE_NONE;
*imsi = NULL;
if (parsed->gsm_type != BSS_MAP_MSG_COMPLETE_LAYER_3) {
LOGP(DNAT, LOGL_ERROR,
"Rejecting CR message due wrong GSM Type %d\n", parsed->gsm_type);
return -1;
}
/* the parsed has had some basic l3 length check */
len = msg->l3h[1];
if (msgb_l3len(msg) - 3 < len) {
LOGP(DNAT, LOGL_ERROR,
"The CR Data has not enough space...\n");
return -1;
}
msg->l4h = &msg->l3h[3];
len -= 1;
tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h, len, 0, 0);
if (!TLVP_PRESENT(&tp, GSM0808_IE_LAYER_3_INFORMATION)) {
LOGP(DNAT, LOGL_ERROR, "CR Data does not contain layer3 information.\n");
return -1;
}
hdr48_len = TLVP_LEN(&tp, GSM0808_IE_LAYER_3_INFORMATION);
if (hdr48_len < sizeof(*hdr48)) {
LOGP(DNAT, LOGL_ERROR, "GSM48 header does not fit.\n");
return -1;
}
hdr48 = (struct gsm48_hdr *) TLVP_VAL(&tp, GSM0808_IE_LAYER_3_INFORMATION);
proto = hdr48->proto_discr & 0x0f;
msg_type = hdr48->msg_type & 0xbf;
if (proto == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_LOC_UPD_REQUEST) {
*con_type = NAT_CON_TYPE_LU;
return _cr_check_loc_upd(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
} else if (proto == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_CM_SERV_REQ) {
*con_type = NAT_CON_TYPE_CM_SERV_REQ;
return _cr_check_cm_serv_req(bsc, &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 = NAT_CON_TYPE_PAG_RESP;
return _cr_check_pag_resp(bsc, &hdr48->data[0], hdr48_len - sizeof(*hdr48), imsi);
} else {
/* We only want to filter the above, let other things pass */
*con_type = NAT_CON_TYPE_OTHER;
return 0;
}
}
struct gsm48_hdr *bsc_unpack_dtap(struct bsc_nat_parsed *parsed,
struct msgb *msg, uint32_t *len)
{
@ -648,34 +395,6 @@ struct gsm48_hdr *bsc_unpack_dtap(struct bsc_nat_parsed *parsed,
return (struct gsm48_hdr *) msg->l4h;
}
int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
struct sccp_connections *con, struct bsc_nat_parsed *parsed)
{
uint32_t len;
uint8_t msg_type, proto;
struct gsm48_hdr *hdr48;
if (con->imsi_checked)
return 0;
/* only care about DTAP messages */
if (parsed->bssap != BSSAP_MSG_DTAP)
return 0;
hdr48 = bsc_unpack_dtap(parsed, msg, &len);
if (!hdr48)
return -1;
proto = hdr48->proto_discr & 0x0f;
msg_type = hdr48->msg_type & 0xbf;
if (proto == GSM48_PDISC_MM &&
msg_type == GSM48_MT_MM_ID_RESP) {
return _dt_check_id_resp(bsc, &hdr48->data[0], len - sizeof(*hdr48), con);
} else {
return 0;
}
}
static const char *con_types [] = {
[NAT_CON_TYPE_NONE] = "n/a",
[NAT_CON_TYPE_LU] = "Location Update",

View File

@ -10,6 +10,7 @@ bsc_nat_test_SOURCES = bsc_nat_test.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_filter.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_sccp.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_utils.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_filter.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_rewrite.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_mgcp_utils.c
bsc_nat_test_LDADD = $(top_builddir)/src/libbsc/libbsc.a \