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import oap_client into libosmogsm 

This imports the code from osmo-msc 6afef893e17bce67e4d4119acd34d480ed03ba77
with minimal changes to make it compile.  Symbol renaming to osmo_
prefix is done separately in a follow-up patch to have a as-clean-as-possible
import first.

Change-Id: I9bc38102318da02d1fe46ef516df3cfd6bf8e3da
This commit is contained in:
Harald Welte 2018-07-30 12:04:21 +02:00
parent baed91709c
commit fdd366ed1b
5 changed files with 369 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/Makefile.am
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@ -100,6 +100,7 @@ nobase_include_HEADERS = \
osmocom/gsm/prim.h \
osmocom/gsm/l1sap.h \
osmocom/gsm/oap.h \
osmocom/gsm/oap_client.h \
osmocom/gsm/protocol/gsm_03_40.h \
osmocom/gsm/protocol/gsm_03_41.h \
osmocom/gsm/protocol/gsm_04_08.h \

82
include/osmocom/gsm/oap_client.h Normal file
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@ -0,0 +1,82 @@
/* 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 osmo_oap_message;
/* This is the config part for vty. It is essentially copied in
* oap_client_state, where values are copied over once the config is
* considered valid. */
struct oap_client_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_client_config, so that a separate validation of the
* config data is possible, and so that only a struct oap_client_state* is
* passed around. */
struct oap_client_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_client_init(struct oap_client_config *config,
struct oap_client_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_client_register(struct oap_client_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_client_handle(struct oap_client_state *state,
const struct msgb *msg_rx, struct msgb **msg_tx);
/* Allocate a msgb and in it, return the encoded oap_client_msg. Return
* NULL on error. (Like oap_client_encode(), but also allocates a msgb.)
* About the name: the idea is do_something(oap_client_encoded(my_struct))
*/
struct msgb *oap_client_encoded(const struct osmo_oap_message *oap_client_msg);

2
src/gsm/Makefile.am
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@ -30,7 +30,7 @@ libgsmint_la_SOURCES = a5.c rxlev_stat.c tlv_parser.c comp128.c comp128v23.c \
milenage/aes-internal.c milenage/aes-internal-enc.c \
milenage/milenage.c gan.c ipa.c gsm0341.c apn.c \
gsup.c gprs_gea.c gsm0503_conv.c oap.c gsm0808_utils.c \
gsm23003.c mncc.c bts_features.c
gsm23003.c mncc.c bts_features.c oap_client.c
libgsmint_la_LDFLAGS = -no-undefined
libgsmint_la_LIBADD = $(top_builddir)/src/libosmocore.la

5
src/gsm/libosmogsm.map
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@ -493,5 +493,10 @@ osmo_mncc_stringify;
osmo_mncc_names;
_osmo_mncc_log;
oap_client_encoded;
oap_client_handle;
oap_client_init;
oap_client_register;
local: *;
};

280
src/gsm/oap_client.c Normal file
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@ -0,0 +1,280 @@
/* 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 <string.h>
#include <errno.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/logging.h>
#include <osmocom/crypt/auth.h>
#include <osmocom/gsm/oap.h>
#include <osmocom/gsm/oap_client.h>
int oap_client_init(struct oap_client_config *config,
struct oap_client_state *state)
{
OSMO_ASSERT(state->state == OAP_UNINITIALIZED);
if (!config)
goto disable;
if (config->client_id == 0)
goto disable;
if (config->secret_k_present == 0) {
LOGP(DLOAP, LOGL_NOTICE, "OAP: client ID set, but secret K missing.\n");
goto disable;
}
if (config->secret_opc_present == 0) {
LOGP(DLOAP, 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_client_state *state,
const uint8_t *rx_random,
const uint8_t *rx_autn,
uint8_t *tx_xres)
{
struct osmo_auth_vector vec;
struct osmo_sub_auth_data auth = {
.type = OSMO_AUTH_TYPE_UMTS,
.algo = OSMO_AUTH_ALG_MILENAGE,
};
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;
}
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 = 41; /* TODO use incrementing sequence nr */
memset(&vec, 0, sizeof(vec));
osmo_auth_gen_vec(&vec, &auth, rx_random);
if (vec.res_len != 8) {
LOGP(DLOAP, LOGL_ERROR, "OAP: Expected XRES to be 8 octets, got %d\n",
vec.res_len);
return -3;
}
if (osmo_constant_time_cmp(vec.autn, rx_autn, sizeof(vec.autn)) != 0) {
LOGP(DLOAP, LOGL_ERROR, "OAP: AUTN mismatch!\n");
LOGP(DLOAP, LOGL_INFO, "OAP: AUTN from server: %s\n",
osmo_hexdump_nospc(rx_autn, sizeof(vec.autn)));
LOGP(DLOAP, 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_client_encoded(const struct osmo_oap_message *oap_msg)
{
struct msgb *msg = msgb_alloc_headroom(1000, 64, __func__);
OSMO_ASSERT(msg);
osmo_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)
{
struct osmo_oap_message oap_msg = {0};
if (client_id < 1) {
LOGP(DLOAP, LOGL_ERROR, "OAP: Invalid client ID: %d\n", client_id);
return NULL;
}
oap_msg.message_type = OAP_MSGT_REGISTER_REQUEST;
oap_msg.client_id = client_id;
return oap_client_encoded(&oap_msg);
}
int oap_client_register(struct oap_client_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 osmo_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_client_encoded(&oap_reply);
}
static int handle_challenge(struct oap_client_state *state,
struct osmo_oap_message *oap_rx,
struct msgb **msg_tx)
{
int rc;
uint8_t xres[8];
if (!(oap_rx->rand_present && oap_rx->autn_present)) {
LOGP(DLOAP, LOGL_ERROR,
"OAP challenge incomplete (rand_present: %d, autn_present: %d)\n",
oap_rx->rand_present, oap_rx->autn_present);
rc = -2;
goto failure;
}
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_client_handle(struct oap_client_state *state,
const struct msgb *msg_rx, struct msgb **msg_tx)
{
uint8_t *data = msgb_l2(msg_rx);
size_t data_len = msgb_l2len(msg_rx);
struct osmo_oap_message oap_msg = {0};
int rc = 0;
*msg_tx = NULL;
OSMO_ASSERT(data);
rc = osmo_oap_decode(&oap_msg, data, data_len);
if (rc < 0) {
LOGP(DLOAP, LOGL_ERROR,
"Decoding OAP message failed with error '%s' (%d)\n",
get_value_string(gsm48_gmm_cause_names, -rc), -rc);
return -10;
}
switch (state->state) {
case OAP_UNINITIALIZED:
LOGP(DLOAP, LOGL_ERROR,
"Received OAP message %d, but the OAP client is"
" not initialized\n", oap_msg.message_type);
return -ENOTCONN;
case OAP_DISABLED:
LOGP(DLOAP, LOGL_ERROR,
"Received OAP message %d, but the OAP client is"
" disabled\n", oap_msg.message_type);
return -ENOTCONN;
default:
break;
}
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(DLOAP, LOGL_ERROR,
"OAP registration failed\n");
state->state = OAP_INITIALIZED;
if (state->registration_failures < 3) {
state->registration_failures++;
return oap_client_register(state, msg_tx);
}
return -11;
case OAP_MSGT_REGISTER_REQUEST:
case OAP_MSGT_CHALLENGE_RESULT:
LOGP(DLOAP, LOGL_ERROR,
"Received invalid OAP message type for OAP client side: %d\n",
(int)oap_msg.message_type);
return -12;
default:
LOGP(DLOAP, LOGL_ERROR,
"Unknown OAP message type: %d\n",
(int)oap_msg.message_type);
return -13;
}
return 0;
}