EAP-SIM/AKA peer: IMSI privacy attribute

Extend IMSI privacy functionality to allow an attribute (in name=value
format) to be added using the new imsi_privacy_attr parameter.

Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>

src/eap_peer/eap_aka.c

@@ -644,11 +644,12 @@ static struct wpabuf * eap_aka_synchronization_failure(
 #ifdef CRYPTO_RSA_OAEP_SHA256
 static struct wpabuf *
 eap_aka_encrypt_identity(struct crypto_rsa_key *imsi_privacy_key,
-			 const u8 *identity, size_t identity_len)
+			 const u8 *identity, size_t identity_len,
+			 const char *attr)
 {
 	struct wpabuf *imsi_buf, *enc;
 	char *b64;
-	size_t b64_len;
+	size_t b64_len, len;
 
 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-AKA: Encrypt permanent identity",
 			  identity, identity_len);
@@ -666,7 +667,10 @@ eap_aka_encrypt_identity(struct crypto_rsa_key *imsi_privacy_key,
 	if (!b64)
 		return NULL;
 
-	enc = wpabuf_alloc(1 + b64_len);
+	len = 1 + b64_len;
+	if (attr)
+		len += 1 + os_strlen(attr);
+	enc = wpabuf_alloc(len);
 	if (!enc) {
 		os_free(b64);
 		return NULL;
@@ -674,6 +678,10 @@ eap_aka_encrypt_identity(struct crypto_rsa_key *imsi_privacy_key,
 	wpabuf_put_u8(enc, '\0');
 	wpabuf_put_data(enc, b64, b64_len);
 	os_free(b64);
+	if (attr) {
+		wpabuf_put_u8(enc, ',');
+		wpabuf_put_str(enc, attr);
+	}
 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-AKA: Encrypted permanent identity",
 			  wpabuf_head(enc), wpabuf_len(enc));
 
@@ -717,9 +725,15 @@ static struct wpabuf * eap_aka_response_identity(struct eap_sm *sm,
 		}
 #ifdef CRYPTO_RSA_OAEP_SHA256
 		if (identity && data->imsi_privacy_key) {
+			struct eap_peer_config *config;
+			const char *attr = NULL;
+
+			config = eap_get_config(sm);
+			if (config)
+				attr = config->imsi_privacy_attr;
 			enc_identity = eap_aka_encrypt_identity(
 				data->imsi_privacy_key,
-				identity, identity_len);
+				identity, identity_len, attr);
 			if (!enc_identity) {
 				wpa_printf(MSG_INFO,
 					   "EAP-AKA: Failed to encrypt permanent identity");

src/eap_peer/eap_config.h

@@ -327,6 +327,16 @@ struct eap_peer_config {
 	 */
 	char *imsi_privacy_cert;
 
+	/**
+	 * imsi_privacy_attr - IMSI privacy attribute
+	 *
+	 * This field is used to help the EAP-SIM/AKA/AKA' server to identify
+	 * the used certificate (and as such, the matching private key). This
+	 * is set to an attribute in name=value format if the operator needs
+	 * this information.
+	 */
+	char *imsi_privacy_attr;
+
 	/**
 	 * machine_identity - EAP Identity for machine credential
 	 *

src/eap_peer/eap_sim.c

@@ -512,11 +512,12 @@ static struct wpabuf * eap_sim_client_error(struct eap_sim_data *data, u8 id,
 #ifdef CRYPTO_RSA_OAEP_SHA256
 static struct wpabuf *
 eap_sim_encrypt_identity(struct crypto_rsa_key *imsi_privacy_key,
-			 const u8 *identity, size_t identity_len)
+			 const u8 *identity, size_t identity_len,
+			 const char *attr)
 {
 	struct wpabuf *imsi_buf, *enc;
 	char *b64;
-	size_t b64_len;
+	size_t b64_len, len;
 
 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM: Encrypt permanent identity",
 			  identity, identity_len);
@@ -534,7 +535,10 @@ eap_sim_encrypt_identity(struct crypto_rsa_key *imsi_privacy_key,
 	if (!b64)
 		return NULL;
 
-	enc = wpabuf_alloc(1 + b64_len);
+	len = 1 + b64_len;
+	if (attr)
+		len += 1 + os_strlen(attr);
+	enc = wpabuf_alloc(len);
 	if (!enc) {
 		os_free(b64);
 		return NULL;
@@ -542,6 +546,10 @@ eap_sim_encrypt_identity(struct crypto_rsa_key *imsi_privacy_key,
 	wpabuf_put_u8(enc, '\0');
 	wpabuf_put_data(enc, b64, b64_len);
 	os_free(b64);
+	if (attr) {
+		wpabuf_put_u8(enc, ',');
+		wpabuf_put_str(enc, attr);
+	}
 	wpa_hexdump_ascii(MSG_DEBUG, "EAP-SIM: Encrypted permanent identity",
 			  wpabuf_head(enc), wpabuf_len(enc));
 
@@ -585,9 +593,15 @@ static struct wpabuf * eap_sim_response_start(struct eap_sm *sm,
 		}
 #ifdef CRYPTO_RSA_OAEP_SHA256
 		if (identity && data->imsi_privacy_key) {
+			struct eap_peer_config *config;
+			const char *attr = NULL;
+
+			config = eap_get_config(sm);
+			if (config)
+				attr = config->imsi_privacy_attr;
 			enc_identity = eap_sim_encrypt_identity(
 				data->imsi_privacy_key,
-				identity, identity_len);
+				identity, identity_len, attr);
 			if (!enc_identity) {
 				wpa_printf(MSG_INFO,
 					   "EAP-SIM: Failed to encrypt permanent identity");

wpa_supplicant/README-HS20

@@ -168,11 +168,16 @@ Credentials can be pre-configured for automatic network selection:
 # milenage: Milenage parameters for SIM/USIM simulator in <Ki>:<OPc>:<SQN>
 #	format
 #
-# imsi_privacy_key: IMSI privacy key (PEM encoded X.509v3 certificate)
+# imsi_privacy_cert: IMSI privacy certificate (PEM encoded X.509v3 certificate)
 #	This field is used with EAP-SIM/AKA/AKA' to encrypt the permanent
 #	identity (IMSI) to improve privacy. The X.509v3 certificate needs to
 #	include a 2048-bit RSA public key and this is from the operator who
 #	authenticates the SIM/USIM.
+# imsi_privacy_attr: IMSI privacy attribute
+#	This field is used to help the EAP-SIM/AKA/AKA' server to identify
+#	the used certificate (and as such, the matching private key). This
+#	is set to an attribute in name=value format if the operator needs
+#	this information.
 #
 # domain_suffix_match: Constraint for server domain name
 #	If set, this FQDN is used as a suffix match requirement for the AAA

wpa_supplicant/config.c

@@ -2504,6 +2504,7 @@ static const struct parse_data ssid_fields[] = {
 	{ INT(eapol_flags) },
 	{ INTe(sim_num, sim_num) },
 	{ STRe(imsi_privacy_cert, imsi_privacy_cert) },
+	{ STRe(imsi_privacy_attr, imsi_privacy_attr) },
 	{ STRe(openssl_ciphers, openssl_ciphers) },
 	{ INTe(erp, erp) },
 #endif /* IEEE8021X_EAPOL */
@@ -2772,6 +2773,7 @@ static void eap_peer_config_free(struct eap_peer_config *eap)
 	os_free(eap->anonymous_identity);
 	os_free(eap->imsi_identity);
 	os_free(eap->imsi_privacy_cert);
+	os_free(eap->imsi_privacy_attr);
 	os_free(eap->machine_identity);
 	bin_clear_free(eap->password, eap->password_len);
 	bin_clear_free(eap->machine_password, eap->machine_password_len);
@@ -2876,6 +2878,7 @@ void wpa_config_free_cred(struct wpa_cred *cred)
 	os_free(cred->req_conn_capab_port);
 	os_free(cred->req_conn_capab_proto);
 	os_free(cred->imsi_privacy_cert);
+	os_free(cred->imsi_privacy_attr);
 	os_free(cred);
 }
 
@@ -3917,6 +3920,12 @@ int wpa_config_set_cred(struct wpa_cred *cred, const char *var,
 		return 0;
 	}
 
+	if (os_strcmp(var, "imsi_privacy_attr") == 0) {
+		os_free(cred->imsi_privacy_attr);
+		cred->imsi_privacy_attr = val;
+		return 0;
+	}
+
 	if (line) {
 		wpa_printf(MSG_ERROR, "Line %d: unknown cred field '%s'.",
 			   line, var);
@@ -4070,6 +4079,9 @@ char * wpa_config_get_cred_no_key(struct wpa_cred *cred, const char *var)
 	if (os_strcmp(var, "imsi_privacy_cert") == 0)
 		return alloc_strdup(cred->imsi_privacy_cert);
 
+	if (os_strcmp(var, "imsi_privacy_attr") == 0)
+		return alloc_strdup(cred->imsi_privacy_attr);
+
 	if (os_strcmp(var, "milenage") == 0) {
 		if (!(cred->milenage))
 			return NULL;

wpa_supplicant/config.h

@@ -190,6 +190,16 @@ struct wpa_cred {
 	 */
 	char *imsi_privacy_cert;
 
+	/**
+	 * imsi_privacy_attr - IMSI privacy attribute
+	 *
+	 * This field is used to help the EAP-SIM/AKA/AKA' server to identify
+	 * the used certificate (and as such, the matching private key). This
+	 * is set to an attribute in name=value format if the operator needs
+	 * this information.
+	 */
+	char *imsi_privacy_attr;
+
 	/**
 	 * engine - Use an engine for private key operations
 	 */

wpa_supplicant/config_file.c

@@ -1036,6 +1036,13 @@ static void wpa_config_write_cred(FILE *f, struct wpa_cred *cred)
 		fprintf(f, "\tcert_id=\"%s\"\n", cred->cert_id);
 	if (cred->ca_cert_id)
 		fprintf(f, "\tca_cert_id=\"%s\"\n", cred->ca_cert_id);
+
+	if (cred->imsi_privacy_cert)
+		fprintf(f, "\timsi_privacy_cert=\"%s\"\n",
+			cred->imsi_privacy_cert);
+	if (cred->imsi_privacy_attr)
+		fprintf(f, "\timsi_privacy_attr=\"%s\"\n",
+			cred->imsi_privacy_attr);
 }
 
 

wpa_supplicant/interworking.c

@@ -1071,6 +1071,12 @@ static int interworking_connect_3gpp(struct wpa_supplicant *wpa_s,
 			goto fail;
 	}
 
+	if (cred->imsi_privacy_attr && cred->imsi_privacy_attr[0]) {
+		if (wpa_config_set_quoted(ssid, "imsi_privacy_attr",
+					  cred->imsi_privacy_attr) < 0)
+			goto fail;
+	}
+
 	wpa_s->next_ssid = ssid;
 	wpa_config_update_prio_list(wpa_s->conf);
 	if (!only_add)