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filter: Separate SCCP/BSSAP extraction and gsm48 code 

For the BSC we will have the gsm48_hdr and don't need to
find data within SCCP. For legacy reasons we need to
initialize con_type, imsi, reject causes early on and
need to do the same in the filter method.
This commit is contained in:
Holger Hans Peter Freyther 2015-04-05 18:07:45 +02:00
parent c36a6d5705
commit 4ba947bf4b
6 changed files with 130 additions and 57 deletions
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11
openbsc/include/openbsc/bsc_msg_filter.h
View File

@ -8,6 +8,7 @@
#include <regex.h>
struct vty;
struct gsm48_hdr;
/* TODO: remove */
struct bsc_nat_parsed;
@ -64,11 +65,13 @@ int bsc_filter_barr_find(struct rb_root *root, const char *imsi, int *cm, int *l
/**
* Content filtering.
*/
int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
struct bsc_nat_parsed *, int *con_type, char **imsi,
int bsc_msg_filter_initial(struct gsm48_hdr *hdr, size_t size,
struct bsc_connection *bsc,
int *con_type, char **imsi,
struct bsc_filter_reject_cause *cause);
int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
struct nat_sccp_connection *con, struct bsc_nat_parsed *parsed,
int bsc_msg_filter_data(struct gsm48_hdr *hdr, size_t size,
struct bsc_connection *bsc,
struct nat_sccp_connection *con,
struct bsc_filter_reject_cause *cause);
/* IMSI allow/deny handling */

8
openbsc/include/openbsc/bsc_nat.h
View File

@ -22,6 +22,7 @@
#define BSC_NAT_H
#include "mgcp.h"
#include "bsc_msg_filter.h"
#include <osmocom/core/select.h>
@ -435,6 +436,13 @@ int bsc_nat_handle_ctrlif_msg(struct bsc_connection *bsc, struct msgb *msg);
int bsc_nat_extract_lac(struct bsc_connection *bsc, struct nat_sccp_connection *con,
struct bsc_nat_parsed *parsed, struct msgb *msg);
int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
struct bsc_nat_parsed *, int *con_type, char **imsi,
struct bsc_filter_reject_cause *cause);
int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
struct nat_sccp_connection *con, struct bsc_nat_parsed *parsed,
struct bsc_filter_reject_cause *cause);
/**
* CTRL interface helper
*/

58
openbsc/src/libfilter/bsc_msg_filter.c
View File

@ -328,14 +328,12 @@ static int _dt_check_id_resp(struct bsc_connection *bsc,
/* 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,
int bsc_msg_filter_initial(struct gsm48_hdr *hdr48, size_t hdr48_len,
struct bsc_connection *bsc,
int *con_type,
char **imsi, struct bsc_filter_reject_cause *cause)
{
struct tlv_parsed tp;
struct gsm48_hdr *hdr48;
int hdr48_len;
int len, ret = 0;
int ret = 0;
uint8_t msg_type, proto;
*con_type = NAT_CON_TYPE_NONE;
@ -343,39 +341,6 @@ int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
*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 &&
@ -412,13 +377,12 @@ int bsc_nat_filter_sccp_cr(struct bsc_connection *bsc, struct msgb *msg,
return auth_imsi(bsc, *imsi, cause);
}
int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
struct nat_sccp_connection *con, struct bsc_nat_parsed *parsed,
int bsc_msg_filter_data(struct gsm48_hdr *hdr48, size_t len,
struct bsc_connection *bsc,
struct nat_sccp_connection *con,
struct bsc_filter_reject_cause *cause)
{
uint32_t len;
uint8_t msg_type, proto;
struct gsm48_hdr *hdr48;
cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
@ -426,14 +390,6 @@ int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
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)

2
openbsc/src/osmo-bsc_nat/Makefile.am
View File

@ -7,7 +7,7 @@ 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_rewrite_trie.c
bsc_nat_rewrite.c bsc_nat_rewrite_trie.c bsc_nat_filter.c
osmo_bsc_nat_LDADD = \
$(top_builddir)/src/libmgcp/libmgcp.a \
$(top_builddir)/src/libbsc/libbsc.a \

105
openbsc/src/osmo-bsc_nat/bsc_nat_filter.c Normal file
View File

@ -0,0 +1,105 @@
/*
* (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_nat.h>
#include <openbsc/bsc_nat_sccp.h>
#include <openbsc/bsc_msg_filter.h>
#include <openbsc/debug.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>
/* 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 bsc_filter_reject_cause *cause)
{
struct tlv_parsed tp;
struct gsm48_hdr *hdr48;
int hdr48_len;
int len;
*con_type = NAT_CON_TYPE_NONE;
cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
*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);
return bsc_msg_filter_initial(hdr48, hdr48_len, bsc, con_type, imsi, cause);
}
int bsc_nat_filter_dt(struct bsc_connection *bsc, struct msgb *msg,
struct nat_sccp_connection *con, struct bsc_nat_parsed *parsed,
struct bsc_filter_reject_cause *cause)
{
uint32_t len;
struct gsm48_hdr *hdr48;
cause->cm_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
cause->lu_reject_cause = GSM48_REJECT_PLMN_NOT_ALLOWED;
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;
return bsc_msg_filter_data(hdr48, len, bsc, con, cause);
}

3
openbsc/tests/bsc-nat/Makefile.am
View File

@ -12,7 +12,8 @@ bsc_nat_test_SOURCES = bsc_nat_test.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_utils.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_rewrite.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_rewrite_trie.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_mgcp_utils.c
$(top_srcdir)/src/osmo-bsc_nat/bsc_mgcp_utils.c \
$(top_srcdir)/src/osmo-bsc_nat/bsc_nat_filter.c
bsc_nat_test_LDADD = \
$(top_builddir)/src/libfilter/libfilter.a \
$(top_builddir)/src/libbsc/libbsc.a \