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EAP-SIM/AKA server: IMSI privacy

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Add support for IMSI privacy in the EAP-SIM/AKA server implementation.
If the new hostapd configuration parameter imsi_privacy_key is used to
specify an RSA private key, that key will be used to decrypt encrypted
permanent identity.

Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>
This commit is contained in:
Jouni Malinen 2022-04-30 16:56:10 +03:00 • committed by Jouni Malinen
parent 36b11bbcff
commit 21098e39fe
9 changed files with 181 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

1
src/ap/ap_config.c
View file

@ -809,6 +809,7 @@ void hostapd_config_free_bss(struct hostapd_bss_config *conf)
os_free(conf->eap_fast_a_id);
os_free(conf->eap_fast_a_id_info);
os_free(conf->eap_sim_db);
os_free(conf->imsi_privacy_key);
os_free(conf->radius_server_clients);
os_free(conf->radius);
os_free(conf->radius_das_shared_secret);

1
src/ap/ap_config.h
View file

@ -443,6 +443,7 @@ struct hostapd_bss_config {
int eap_teap_id;
int eap_sim_aka_result_ind;
int eap_sim_id;
char *imsi_privacy_key;
int tnc;
int fragment_size;
u16 pwd_group;

23
src/ap/authsrv.c
View file

@ -9,6 +9,7 @@
#include "utils/includes.h"
#include "utils/common.h"
#include "crypto/crypto.h"
#include "crypto/tls.h"
#include "eap_server/eap.h"
#include "eap_server/eap_sim_db.h"
@ -209,6 +210,7 @@ static struct eap_config * authsrv_eap_config(struct hostapd_data *hapd)
cfg->eap_teap_id = hapd->conf->eap_teap_id;
cfg->eap_sim_aka_result_ind = hapd->conf->eap_sim_aka_result_ind;
cfg->eap_sim_id = hapd->conf->eap_sim_id;
cfg->imsi_privacy_key = hapd->imsi_privacy_key;
cfg->tnc = hapd->conf->tnc;
cfg->wps = hapd->wps;
cfg->fragment_size = hapd->conf->fragment_size;
@ -295,6 +297,22 @@ int authsrv_init(struct hostapd_data *hapd)
}
#endif /* EAP_TLS_FUNCS */
#ifdef CRYPTO_RSA_OAEP_SHA256
crypto_rsa_key_free(hapd->imsi_privacy_key);
hapd->imsi_privacy_key = NULL;
if (hapd->conf->imsi_privacy_key) {
hapd->imsi_privacy_key = crypto_rsa_key_read(
hapd->conf->imsi_privacy_key, true);
if (!hapd->imsi_privacy_key) {
wpa_printf(MSG_ERROR,
"Failed to read/parse IMSI privacy key %s",
hapd->conf->imsi_privacy_key);
authsrv_deinit(hapd);
return -1;
}
}
#endif /* CRYPTO_RSA_OAEP_SHA256 */
#ifdef EAP_SIM_DB
if (hapd->conf->eap_sim_db) {
hapd->eap_sim_db_priv =
@ -335,6 +353,11 @@ void authsrv_deinit(struct hostapd_data *hapd)
hapd->radius_srv = NULL;
#endif /* RADIUS_SERVER */
#ifdef CRYPTO_RSA_OAEP_SHA256
crypto_rsa_key_free(hapd->imsi_privacy_key);
hapd->imsi_privacy_key = NULL;
#endif /* CRYPTO_RSA_OAEP_SHA256 */
#ifdef EAP_TLS_FUNCS
if (hapd->ssl_ctx) {
tls_deinit(hapd->ssl_ctx);

1
src/ap/hostapd.h
View file

@ -208,6 +208,7 @@ struct hostapd_data {
void *ssl_ctx;
void *eap_sim_db_priv;
struct crypto_rsa_key *imsi_privacy_key;
struct radius_server_data *radius_srv;
struct dl_list erp_keys; /* struct eap_server_erp_key */

3
src/eap_server/eap.h
View file

@ -124,6 +124,9 @@ struct eap_config {
* callback context.
*/
void *eap_sim_db_priv;
struct crypto_rsa_key *imsi_privacy_key;
bool backend_auth;
int eap_server;

83
src/eap_server/eap_server_aka.c
View file

@ -9,6 +9,7 @@
#include "includes.h"
#include "common.h"
#include "utils/base64.h"
#include "crypto/sha256.h"
#include "crypto/crypto.h"
#include "crypto/random.h"
@ -737,11 +738,8 @@ static void eap_aka_determine_identity(struct eap_sm *sm,
sm->identity, sm->identity_len);
username = sim_get_username(sm->identity, sm->identity_len);
if (username == NULL) {
data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
eap_aka_state(data, NOTIFICATION);
return;
}
if (!username)
goto fail;
if (eap_aka_check_identity_reauth(sm, data, username) > 0) {
os_free(username);
@ -785,16 +783,87 @@ static void eap_aka_determine_identity(struct eap_sm *sm,
username);
os_strlcpy(data->permanent, username, sizeof(data->permanent));
os_free(username);
#ifdef CRYPTO_RSA_OAEP_SHA256
} else if (sm->identity_len > 1 && sm->identity[0] == '\0') {
char *enc_id, *pos, *end;
size_t enc_id_len;
u8 *decoded_id;
size_t decoded_id_len;
struct wpabuf *enc, *dec;
u8 *new_id;
os_free(username);
if (!sm->cfg->imsi_privacy_key) {
wpa_printf(MSG_DEBUG,
"EAP-AKA: Received encrypted identity, but no IMSI privacy key configured to decrypt it");
goto fail;
}
enc_id = (char *) &sm->identity[1];
end = (char *) &sm->identity[sm->identity_len];
for (pos = enc_id; pos < end; pos++) {
if (*pos == ',')
break;
}
enc_id_len = pos - enc_id;
wpa_hexdump_ascii(MSG_DEBUG,
"EAP-AKA: Encrypted permanent identity",
enc_id, enc_id_len);
decoded_id = base64_decode(enc_id, enc_id_len, &decoded_id_len);
if (!decoded_id) {
wpa_printf(MSG_DEBUG,
"EAP-AKA: Could not base64 decode encrypted identity");
goto fail;
}
wpa_hexdump(MSG_DEBUG,
"EAP-AKA: Decoded encrypted permanent identity",
decoded_id, decoded_id_len);
enc = wpabuf_alloc_copy(decoded_id, decoded_id_len);
os_free(decoded_id);
if (!enc)
goto fail;
dec = crypto_rsa_oaep_sha256_decrypt(sm->cfg->imsi_privacy_key,
enc);
wpabuf_free(enc);
if (!dec) {
wpa_printf(MSG_DEBUG,
"EAP-AKA: Failed to decrypt encrypted identity");
goto fail;
}
wpa_hexdump_ascii(MSG_DEBUG, "EAP-AKA: Decrypted permanent identity",
wpabuf_head(dec), wpabuf_len(dec));
username = sim_get_username(wpabuf_head(dec), wpabuf_len(dec));
if (!username) {
wpabuf_free(dec);
goto fail;
}
new_id = os_memdup(wpabuf_head(dec), wpabuf_len(dec));
if (!new_id) {
wpabuf_free(dec);
goto fail;
}
os_free(sm->identity);
sm->identity = new_id;
sm->identity_len = wpabuf_len(dec);
wpabuf_free(dec);
os_strlcpy(data->permanent, username, sizeof(data->permanent));
os_free(username);
#endif /* CRYPTO_RSA_OAEP_SHA256 */
} else {
wpa_printf(MSG_DEBUG, "EAP-AKA: Unrecognized username '%s'",
username);
os_free(username);
data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
eap_aka_state(data, NOTIFICATION);
goto fail;
return;
}
eap_aka_fullauth(sm, data);
return;
fail:
data->notification = EAP_SIM_GENERAL_FAILURE_BEFORE_AUTH;
eap_aka_state(data, NOTIFICATION);
}

69
src/eap_server/eap_server_sim.c
View file

@ -9,6 +9,8 @@
#include "includes.h"
#include "common.h"
#include "utils/base64.h"
#include "crypto/crypto.h"
#include "crypto/random.h"
#include "eap_server/eap_i.h"
#include "eap_common/eap_sim_common.h"
@ -512,6 +514,73 @@ static void eap_sim_process_start(struct eap_sm *sm,
username);
os_strlcpy(data->permanent, username, sizeof(data->permanent));
os_free(username);
#ifdef CRYPTO_RSA_OAEP_SHA256
} else if (sm->identity_len > 1 && sm->identity[0] == '\0') {
char *enc_id, *pos, *end;
size_t enc_id_len;
u8 *decoded_id;
size_t decoded_id_len;
struct wpabuf *enc, *dec;
u8 *new_id;
os_free(username);
if (!sm->cfg->imsi_privacy_key) {
wpa_printf(MSG_DEBUG,
"EAP-SIM: Received encrypted identity, but no IMSI privacy key configured to decrypt it");
goto failed;
}
enc_id = (char *) &sm->identity[1];
end = (char *) &sm->identity[sm->identity_len];
for (pos = enc_id; pos < end; pos++) {
if (*pos == ',')
break;
}
enc_id_len = pos - enc_id;
wpa_hexdump_ascii(MSG_DEBUG,
"EAP-SIM: Encrypted permanent identity",
enc_id, enc_id_len);
decoded_id = base64_decode(enc_id, enc_id_len, &decoded_id_len);
if (!decoded_id) {
wpa_printf(MSG_DEBUG,
"EAP-SIM: Could not base64 decode encrypted identity");
goto failed;
}
wpa_hexdump(MSG_DEBUG,
"EAP-SIM: Decoded encrypted permanent identity",
decoded_id, decoded_id_len);
enc = wpabuf_alloc_copy(decoded_id, decoded_id_len);
os_free(decoded_id);
if (!enc)
goto failed;
dec = crypto_rsa_oaep_sha256_decrypt(sm->cfg->imsi_privacy_key,
enc);
wpabuf_free(enc);
if (!dec) {
wpa_printf(MSG_DEBUG,
"EAP-SIM: Failed to decrypt encrypted identity");
goto failed;
}
wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM: Decrypted permanent identity",
wpabuf_head(dec), wpabuf_len(dec));
username = sim_get_username(wpabuf_head(dec), wpabuf_len(dec));
if (!username) {
wpabuf_free(dec);
goto failed;
}
new_id = os_memdup(wpabuf_head(dec), wpabuf_len(dec));
if (!new_id) {
wpabuf_free(dec);
goto failed;
}
os_free(sm->identity);
sm->identity = new_id;
sm->identity_len = wpabuf_len(dec);
wpabuf_free(dec);
os_strlcpy(data->permanent, username, sizeof(data->permanent));
os_free(username);
#endif /* CRYPTO_RSA_OAEP_SHA256 */
} else {
wpa_printf(MSG_DEBUG, "EAP-SIM: Unrecognized username '%s'",
username);