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oap: implement initial OAP API. 

Add oap.[hc] and oap_messages.[hc].

Sponsored-by: On-Waves ehf
This commit is contained in:
Neels Hofmeyr 2015-10-12 11:57:34 +02:00 committed by Holger Hans Peter Freyther
parent d48f057328
commit d739f092be
6 changed files with 586 additions and 2 deletions
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3
openbsc/include/openbsc/Makefile.am
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@ -16,7 +16,8 @@ noinst_HEADERS = abis_nm.h abis_rsl.h db.h gsm_04_08.h gsm_data.h \
arfcn_range_encode.h nat_rewrite_trie.h bsc_nat_callstats.h \
osmux.h mgcp_transcode.h gprs_utils.h utils.h \
gprs_gb_parse.h smpp.h meas_feed.h gprs_gsup_messages.h \
gprs_gsup_client.h bsc_msg_filter.h
gprs_gsup_client.h bsc_msg_filter.h \
oap.h oap_messages.h
openbsc_HEADERS = gsm_04_08.h meas_rep.h bsc_api.h
openbscdir = $(includedir)/openbsc

78
openbsc/include/openbsc/oap.h Normal file
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@ -0,0 +1,78 @@
/* Osmocom Authentication Protocol API */
/* (C) 2015 by Sysmocom s.f.m.c. GmbH
* All Rights Reserved
*
* Author: Neels Hofmeyr
*
* 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/>.
*
*/
#pragma once
#include <stdint.h>
struct msgb;
struct oap_message;
/* This is the config part for vty. It is essentially copied in oap_state,
* where values are copied over once the config is considered valid. */
struct oap_config {
uint16_t client_id;
int secret_k_present;
uint8_t secret_k[16];
int secret_opc_present;
uint8_t secret_opc[16];
};
/* The runtime state of the OAP client. client_id and the secrets are in fact
* duplicated from oap_config, so that a separate validation of the config data
* is possible, and so that only a struct oap_state* is passed around. */
struct oap_state {
enum {
OAP_UNINITIALIZED = 0, /* just allocated. */
OAP_DISABLED, /* disabled by config. */
OAP_INITIALIZED, /* enabled, config is valid. */
OAP_REQUESTED_CHALLENGE,
OAP_SENT_CHALLENGE_RESULT,
OAP_REGISTERED
} state;
uint16_t client_id;
uint8_t secret_k[16];
uint8_t secret_opc[16];
int registration_failures;
};
/* From config, initialize state. Return 0 on success. */
int oap_init(struct oap_config *config, struct oap_state *state);
/* Construct an OAP registration message and return in *msg_tx. Use
* state->client_id and update state->state.
* Return 0 on success, or a negative value on error.
* If an error is returned, *msg_tx is guaranteed to be NULL. */
int oap_register(struct oap_state *state, struct msgb **msg_tx);
/* Decode and act on a received OAP message msg_rx. Update state->state. If a
* non-NULL pointer is returned in *msg_tx, that msgb should be sent to the OAP
* server (and freed) by the caller. The received msg_rx is not freed.
* Return 0 on success, or a negative value on error.
* If an error is returned, *msg_tx is guaranteed to be NULL. */
int oap_handle(struct oap_state *state, const struct msgb *msg_rx, struct msgb **msg_tx);
/* Allocate a msgb and in it, return the encoded oap_msg. Return NULL on
* error. (Like oap_encode(), but also allocates a msgb.)
* About the name: the idea is do_something(oap_encoded(my_struct)) */
struct msgb *oap_encoded(const struct oap_message *oap_msg);

70
openbsc/include/openbsc/oap_messages.h Normal file
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@ -0,0 +1,70 @@
/* Osmocom Authentication Protocol message encoder/decoder */
/* (C) 2015 by Sysmocom s.f.m.c. GmbH
* All Rights Reserved
*
* Author: Neels Hofmeyr
*
* 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/>.
*
*/
#pragma once
#include <stdint.h>
#include <openbsc/gsm_04_08_gprs.h>
#include <openbsc/gsm_data.h>
/* Some numbers are out of sequence because (so far) they match gprs_gsup_iei.
*/
enum oap_iei {
OAP_CAUSE_IE = 0x02,
OAP_RAND_IE = 0x20,
OAP_AUTN_IE = 0x23,
OAP_XRES_IE = 0x24,
OAP_AUTS_IE = 0x25,
OAP_CLIENT_ID_IE = 0x30,
};
enum oap_message_type {
OAP_MSGT_REGISTER_REQUEST = 0b00000100,
OAP_MSGT_REGISTER_ERROR = 0b00000101,
OAP_MSGT_REGISTER_RESULT = 0b00000110,
OAP_MSGT_CHALLENGE_REQUEST = 0b00001000,
OAP_MSGT_CHALLENGE_ERROR = 0b00001001,
OAP_MSGT_CHALLENGE_RESULT = 0b00001010,
OAP_MSGT_SYNC_REQUEST = 0b00001100,
OAP_MSGT_SYNC_ERROR = 0b00001101,
OAP_MSGT_SYNC_RESULT = 0b00001110,
};
struct oap_message {
enum oap_message_type message_type;
enum gsm48_gmm_cause cause;
uint16_t client_id;
int rand_present;
uint8_t rand[16];
int autn_present;
uint8_t autn[16];
int xres_present;
uint8_t xres[8];
int auts_present;
uint8_t auts[16];
};
int oap_decode(const uint8_t *data, size_t data_len,
struct oap_message *oap_msg);
void oap_encode(struct msgb *msg, const struct oap_message *oap_msg);

3
openbsc/src/gprs/Makefile.am
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@ -27,7 +27,8 @@ osmo_sgsn_SOURCES = gprs_gmm.c gprs_sgsn.c gprs_sndcp.c gprs_sndcp_vty.c \
gprs_llc.c gprs_llc_parse.c gprs_llc_vty.c crc24.c \
sgsn_ctrl.c sgsn_auth.c gprs_subscriber.c \
gprs_gsup_messages.c gprs_utils.c gprs_gsup_client.c \
gsm_04_08_gprs.c sgsn_cdr.c sgsn_ares.c
gsm_04_08_gprs.c sgsn_cdr.c sgsn_ares.c \
oap.c oap_messages.c
osmo_sgsn_LDADD = \
$(top_builddir)/src/libcommon/libcommon.a \
-lgtp $(OSMO_LIBS) $(LIBOSMOABIS_LIBS) $(LIBCARES_LIBS) \

256
openbsc/src/gprs/oap.c Normal file
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@ -0,0 +1,256 @@
/* Osmocom Authentication Protocol API */
/* (C) 2015 by Sysmocom s.f.m.c. GmbH
* All Rights Reserved
*
* Author: Neels Hofmeyr
*
* 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 <osmocom/crypt/auth.h>
#include <openbsc/oap.h>
#include <openbsc/utils.h>
#include <openbsc/debug.h>
#include <openbsc/oap_messages.h>
int oap_init(struct oap_config *config, struct oap_state *state)
{
OSMO_ASSERT(state->state == OAP_UNINITIALIZED);
if (config->client_id == 0)
goto disable;
if (config->secret_k_present == 0) {
LOGP(DGPRS, LOGL_NOTICE, "OAP: client ID set, but secret K missing.\n");
goto disable;
}
if (config->secret_opc_present == 0) {
LOGP(DGPRS, LOGL_NOTICE, "OAP: client ID set, but secret OPC missing.\n");
goto disable;
}
state->client_id = config->client_id;
memcpy(state->secret_k, config->secret_k, sizeof(state->secret_k));
memcpy(state->secret_opc, config->secret_opc, sizeof(state->secret_opc));
state->state = OAP_INITIALIZED;
return 0;
disable:
state->state = OAP_DISABLED;
return 0;
}
/* From the given state and received RAND and AUTN octets, validate the
* server's authenticity and formulate the matching milenage reply octets in
* *tx_xres. The state is not modified.
* On success, and if tx_res is not NULL, exactly 8 octets will be written to
* *tx_res. If not NULL, tx_res must point at allocated memory of at least 8
* octets. The caller will want to send XRES back to the server in a challenge
* response message and update the state.
* Return 0 on success; -1 if OAP is disabled; -2 if rx_random and rx_autn fail
* the authentication check; -3 for any other errors. */
static int oap_evaluate_challenge(const struct oap_state *state,
const uint8_t *rx_random,
const uint8_t *rx_autn,
uint8_t *tx_xres)
{
osmo_static_assert(sizeof(((struct osmo_sub_auth_data*)0)->u.umts.k)
== sizeof(state->secret_k), _secret_k_size_match);
osmo_static_assert(sizeof(((struct osmo_sub_auth_data*)0)->u.umts.opc)
== sizeof(state->secret_opc), _secret_opc_size_match);
switch(state->state) {
case OAP_UNINITIALIZED:
case OAP_DISABLED:
return -1;
default:
break;
}
struct osmo_auth_vector vec;
struct osmo_sub_auth_data auth = {
.type = OSMO_AUTH_TYPE_UMTS,
.algo = OSMO_AUTH_ALG_MILENAGE,
};
memcpy(auth.u.umts.k, state->secret_k, sizeof(auth.u.umts.k));
memcpy(auth.u.umts.opc, state->secret_opc, sizeof(auth.u.umts.opc));
memset(auth.u.umts.amf, '\0', sizeof(auth.u.umts.amf));
auth.u.umts.sqn = 42; /* TODO use incrementing sequence nr */
memset(&vec, 0, sizeof(vec));
osmo_auth_gen_vec(&vec, &auth, rx_random);
if (vec.res_len != 8) {
LOGP(DGPRS, LOGL_ERROR, "OAP: Expected XRES to be 8 octets, got %d\n",
vec.res_len);
return -3;
}
if (constant_time_cmp(vec.autn, rx_autn, sizeof(vec.autn)) != 0) {
LOGP(DGPRS, LOGL_ERROR, "OAP: AUTN mismatch!\n");
LOGP(DGPRS, LOGL_INFO, "OAP: AUTN from server: %s\n",
osmo_hexdump_nospc(rx_autn, sizeof(vec.autn)));
LOGP(DGPRS, LOGL_INFO, "OAP: AUTN expected: %s\n",
osmo_hexdump_nospc(vec.autn, sizeof(vec.autn)));
return -2;
}
if (tx_xres != NULL)
memcpy(tx_xres, vec.res, 8);
return 0;
}
struct msgb *oap_encoded(const struct oap_message *oap_msg)
{
struct msgb *msg = msgb_alloc_headroom(1000, 64, __func__);
OSMO_ASSERT(msg);
oap_encode(msg, oap_msg);
return msg;
}
/* Create a new msgb containing an OAP registration message.
* On error, return NULL. */
static struct msgb* oap_msg_register(uint16_t client_id)
{
if (client_id < 1) {
LOGP(DGPRS, LOGL_ERROR, "OAP: Invalid client ID: %d\n", client_id);
return NULL;
}
struct oap_message oap_msg = {0};
oap_msg.message_type = OAP_MSGT_REGISTER_REQUEST;
oap_msg.client_id = client_id;
return oap_encoded(&oap_msg);
}
int oap_register(struct oap_state *state, struct msgb **msg_tx)
{
*msg_tx = oap_msg_register(state->client_id);
if (!(*msg_tx))
return -1;
state->state = OAP_REQUESTED_CHALLENGE;
return 0;
}
/* Create a new msgb containing an OAP challenge response message.
* xres must point at 8 octets to return as challenge response.
* On error, return NULL. */
static struct msgb* oap_msg_challenge_response(uint8_t *xres)
{
struct oap_message oap_reply = {0};
oap_reply.message_type = OAP_MSGT_CHALLENGE_RESULT;
memcpy(oap_reply.xres, xres, sizeof(oap_reply.xres));
oap_reply.xres_present = 1;
return oap_encoded(&oap_reply);
}
static int handle_challenge(struct oap_state *state,
struct oap_message *oap_rx,
struct msgb **msg_tx)
{
int rc;
if (!(oap_rx->rand_present && oap_rx->autn_present)) {
LOGP(DGPRS, LOGL_ERROR,
"OAP challenge incomplete (rand_present: %d, autn_present: %d)\n",
oap_rx->rand_present, oap_rx->autn_present);
rc = -2;
goto failure;
}
uint8_t xres[8];
rc = oap_evaluate_challenge(state,
oap_rx->rand,
oap_rx->autn,
xres);
if (rc < 0)
goto failure;
*msg_tx = oap_msg_challenge_response(xres);
if ((*msg_tx) == NULL) {
rc = -1;
goto failure;
}
state->state = OAP_SENT_CHALLENGE_RESULT;
return 0;
failure:
OSMO_ASSERT(rc < 0);
state->state = OAP_INITIALIZED;
return rc;
}
int oap_handle(struct oap_state *state, const struct msgb *msg_rx, struct msgb **msg_tx)
{
*msg_tx = NULL;
uint8_t *data = msgb_l2(msg_rx);
size_t data_len = msgb_l2len(msg_rx);
int rc = 0;
struct oap_message oap_msg = {0};
OSMO_ASSERT(data);
rc = oap_decode(data, data_len, &oap_msg);
if (rc < 0) {
LOGP(DGPRS, LOGL_ERROR,
"Decoding OAP message failed with error '%s' (%d)\n",
get_value_string(gsm48_gmm_cause_names, -rc), -rc);
return -10;
}
switch (oap_msg.message_type) {
case OAP_MSGT_CHALLENGE_REQUEST:
return handle_challenge(state, &oap_msg, msg_tx);
case OAP_MSGT_REGISTER_RESULT:
/* successfully registered */
state->state = OAP_REGISTERED;
break;
case OAP_MSGT_REGISTER_ERROR:
LOGP(DGPRS, LOGL_ERROR,
"OAP registration failed\n");
state->state = OAP_INITIALIZED;
if (state->registration_failures < 3) {
state->registration_failures ++;
return oap_register(state, msg_tx);
}
return -11;
case OAP_MSGT_REGISTER_REQUEST:
case OAP_MSGT_CHALLENGE_RESULT:
LOGP(DGPRS, LOGL_ERROR,
"Received invalid OAP message type for OAP client side: %d\n",
(int)oap_msg.message_type);
return -12;
default:
LOGP(DGPRS, LOGL_ERROR,
"Unknown OAP message type: %d\n",
(int)oap_msg.message_type);
return -13;
}
return 0;
}

178
openbsc/src/gprs/oap_messages.c Normal file
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@ -0,0 +1,178 @@
/* Osmocom Authentication Protocol message encoder/decoder */
/* (C) 2015 by Sysmocom s.f.m.c. GmbH
* All Rights Reserved
*
* Author: Neels Hofmeyr
*
* 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/oap_messages.h>
#include <openbsc/debug.h>
#include <openbsc/gprs_utils.h>
#include <openbsc/utils.h>
#include <osmocom/gsm/tlv.h>
#include <osmocom/core/msgb.h>
#include <stdint.h>
int oap_decode(const uint8_t *const_data, size_t data_len,
struct oap_message *oap_msg)
{
int rc;
uint8_t tag;
/* the shift/match functions expect non-const pointers, but we'll
* either copy the data or cast pointers back to const before returning
* them
*/
uint8_t *data = (uint8_t *)const_data;
uint8_t *value;
size_t value_len;
memset(oap_msg, 0, sizeof(*oap_msg));
/* message type */
rc = gprs_shift_v_fixed(&data, &data_len, 1, &value);
if (rc < 0)
return -GMM_CAUSE_INV_MAND_INFO;
oap_msg->message_type = decode_big_endian(value, 1);
/* specific parts */
while (data_len > 0) {
enum oap_iei iei;
rc = gprs_shift_tlv(&data, &data_len, &tag, &value, &value_len);
if (rc < 0)
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
iei = tag;
switch (iei) {
case OAP_CLIENT_ID_IE:
if (value_len != 2) {
LOGP(DGPRS, LOGL_NOTICE,
"OAP IE type client ID (%d) should be 2 octets, but has %d\n",
(int)iei, (int)value_len);
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
}
oap_msg->client_id = decode_big_endian(value, value_len);
if (oap_msg->client_id == 0) {
LOGP(DGPRS, LOGL_NOTICE,
"OAP IE type client ID (%d): client ID must be nonzero.\n",
(int)iei);
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
}
break;
case OAP_AUTN_IE:
if (value_len != sizeof(oap_msg->autn)) {
LOGP(DGPRS, LOGL_NOTICE,
"OAP IE type AUTN (%d) should be %d octets, but has %d\n",
(int)iei, (int)sizeof(oap_msg->autn), (int)value_len);
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
}
memcpy(oap_msg->autn, value, value_len);
oap_msg->autn_present = value_len;
break;
case OAP_RAND_IE:
if (value_len != sizeof(oap_msg->rand)) {
LOGP(DGPRS, LOGL_NOTICE,
"OAP IE type RAND (%d) should be %d octets, but has %d\n",
(int)iei, (int)sizeof(oap_msg->rand), (int)value_len);
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
}
memcpy(oap_msg->rand, value, value_len);
oap_msg->rand_present = value_len;
break;
case OAP_XRES_IE:
if (value_len != sizeof(oap_msg->xres)) {
LOGP(DGPRS, LOGL_NOTICE,
"OAP IE type XRES (%d) should be %d octets, but has %d\n",
(int)iei, (int)sizeof(oap_msg->xres), (int)value_len);
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
}
memcpy(oap_msg->xres, value, value_len);
oap_msg->xres_present = value_len;
break;
case OAP_AUTS_IE:
if (value_len != sizeof(oap_msg->auts)) {
LOGP(DGPRS, LOGL_NOTICE,
"OAP IE type AUTS (%d) should be %d octets, but has %d\n",
(int)iei, (int)sizeof(oap_msg->auts), (int)value_len);
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
}
memcpy(oap_msg->auts, value, value_len);
oap_msg->auts_present = value_len;
break;
case OAP_CAUSE_IE:
if (value_len > 1) {
LOGP(DGPRS, LOGL_ERROR,
"OAP cause may not exceed one octet, is %d", (int)value_len);
return -GMM_CAUSE_PROTO_ERR_UNSPEC;
}
oap_msg->cause = *value;
break;
default:
LOGP(DGPRS, LOGL_NOTICE,
"OAP IE type %d unknown\n", iei);
continue;
}
}
return 0;
}
void oap_encode(struct msgb *msg, const struct oap_message *oap_msg)
{
uint8_t u8;
/* generic part */
OSMO_ASSERT(oap_msg->message_type);
msgb_v_put(msg, (uint8_t)oap_msg->message_type);
/* specific parts */
if ((u8 = oap_msg->cause))
msgb_tlv_put(msg, OAP_CAUSE_IE, sizeof(u8), &u8);
if (oap_msg->client_id > 0)
msgb_tlv_put(msg, OAP_CLIENT_ID_IE, sizeof(oap_msg->client_id),
encode_big_endian(oap_msg->client_id, sizeof(oap_msg->client_id)));
if (oap_msg->rand_present)
msgb_tlv_put(msg, OAP_RAND_IE, sizeof(oap_msg->rand), oap_msg->rand);
if (oap_msg->autn_present)
msgb_tlv_put(msg, OAP_AUTN_IE, sizeof(oap_msg->autn), oap_msg->autn);
if (oap_msg->auts_present)
msgb_tlv_put(msg, OAP_AUTS_IE, sizeof(oap_msg->auts), oap_msg->auts);
if (oap_msg->xres_present)
msgb_tlv_put(msg, OAP_XRES_IE, sizeof(oap_msg->xres), oap_msg->xres);
msg->l2h = msg->data;
}