OWE: Allow set of enabled DH groups to be limited on AP

The new hostapd configuration parameter owe_groups can be used to
specify a subset of the allowed DH groups as a space separated list of
group identifiers.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

hostapd/config_file.c

@@ -3795,7 +3795,13 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 	} else if (os_strcmp(buf, "owe_transition_ifname") == 0) {
 		os_strlcpy(bss->owe_transition_ifname, pos,
 			   sizeof(bss->owe_transition_ifname));
-
+	} else if (os_strcmp(buf, "owe_groups") == 0) {
+		if (hostapd_parse_intlist(&bss->owe_groups, pos)) {
+			wpa_printf(MSG_ERROR,
+				   "Line %d: Invalid owe_groups value '%s'",
+				   line, pos);
+			return 1;
+		}
 #endif /* CONFIG_OWE */
 	} else {
 		wpa_printf(MSG_ERROR,

hostapd/hostapd.conf

@@ -1407,6 +1407,15 @@ own_ip_addr=127.0.0.1
 # 1-65535 DH Group to use for FILS PFS
 #fils_dh_group=0
 
+# OWE DH groups
+# OWE implementations are required to support group 19 (NIST P-256). All groups
+# that are supported by the implementation (e.g., groups 19, 20, and 21 when
+# using OpenSSL) are enabled by default. This configuration parameter can be
+# used to specify a limited set of allowed groups. The group values are listed
+# in the IANA registry:
+# http://www.iana.org/assignments/ipsec-registry/ipsec-registry.xml#ipsec-registry-10
+#owe_groups=19 20 21
+
 # OWE transition mode configuration
 # Pointer to the matching open/OWE BSS
 #owe_transition_bssid=<bssid>

src/ap/ap_config.c

@@ -610,6 +610,9 @@ void hostapd_config_free_bss(struct hostapd_bss_config *conf)
 	wpabuf_free(conf->assocresp_elements);
 
 	os_free(conf->sae_groups);
+#ifdef CONFIG_OWE
+	os_free(conf->owe_groups);
+#endif /* CONFIG_OWE */
 
 	os_free(conf->wowlan_triggers);
 

src/ap/ap_config.h

@@ -649,6 +649,7 @@ struct hostapd_bss_config {
 	u8 owe_transition_ssid[SSID_MAX_LEN];
 	size_t owe_transition_ssid_len;
 	char owe_transition_ifname[IFNAMSIZ + 1];
+	int *owe_groups;
 #endif /* CONFIG_OWE */
 };
 

src/ap/ieee802_11.c

@@ -2128,6 +2128,27 @@ static u16 check_ext_capab(struct hostapd_data *hapd, struct sta_info *sta,
 
 
 #ifdef CONFIG_OWE
+
+static int owe_group_supported(struct hostapd_data *hapd, u16 group)
+{
+	int i;
+	int *groups = hapd->conf->owe_groups;
+
+	if (group != 19 && group != 20 && group != 21)
+		return 0;
+
+	if (!groups)
+		return 1;
+
+	for (i = 0; groups[i] > 0; i++) {
+		if (groups[i] == group)
+			return 1;
+	}
+
+	return 0;
+}
+
+
 static u16 owe_process_assoc_req(struct hostapd_data *hapd,
 				 struct sta_info *sta, const u8 *owe_dh,
 				 u8 owe_dh_len)
@@ -2147,6 +2168,10 @@ static u16 owe_process_assoc_req(struct hostapd_data *hapd,
 	}
 
 	group = WPA_GET_LE16(owe_dh);
+	if (!owe_group_supported(hapd, group)) {
+		wpa_printf(MSG_DEBUG, "OWE: Unsupported DH group %u", group);
+		return WLAN_STATUS_FINITE_CYCLIC_GROUP_NOT_SUPPORTED;
+	}
 	if (group == 19)
 		prime_len = 32;
 	else if (group == 20)
@@ -2265,6 +2290,7 @@ static u16 owe_process_assoc_req(struct hostapd_data *hapd,
 
 	return WLAN_STATUS_SUCCESS;
 }
+
 #endif /* CONFIG_OWE */