SAE-PK: Testing functionality to allow behavior overrides

The new sae_commit_status and sae_pk_omit configuration parameters and
an extra key at the end of sae_password pk argument can be used to
override SAE-PK behavior for testing purposes.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

hostapd/config_file.c

@@ -4231,6 +4231,10 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 		bss->own_ie_override = tmp;
 	} else if (os_strcmp(buf, "sae_reflection_attack") == 0) {
 		bss->sae_reflection_attack = atoi(pos);
+	} else if (os_strcmp(buf, "sae_commit_status") == 0) {
+		bss->sae_commit_status = atoi(pos);
+	} else if (os_strcmp(buf, "sae_pk_omit") == 0) {
+		bss->sae_pk_omit = atoi(pos);
 	} else if (os_strcmp(buf, "sae_commit_override") == 0) {
 		wpabuf_free(bss->sae_commit_override);
 		bss->sae_commit_override = wpabuf_parse_bin(pos);

src/ap/ap_config.c

@@ -160,6 +160,10 @@ void hostapd_config_defaults_bss(struct hostapd_bss_config *bss)
 
 	/* Default to strict CRL checking. */
 	bss->check_crl_strict = 1;
+
+#ifdef CONFIG_TESTING_OPTIONS
+	bss->sae_commit_status = -1;
+#endif /* CONFIG_TESTING_OPTIONS */
 }
 
 

src/ap/ap_config.h

@@ -678,6 +678,8 @@ struct hostapd_bss_config {
 	u8 bss_load_test_set;
 	struct wpabuf *own_ie_override;
 	int sae_reflection_attack;
+	int sae_commit_status;
+	int sae_pk_omit;
 	struct wpabuf *sae_commit_override;
 	struct wpabuf *rsne_override_eapol;
 	struct wpabuf *rsnxe_override_eapol;

src/ap/ieee802_11.c

@@ -567,6 +567,13 @@ static struct wpabuf * auth_build_sae_confirm(struct hostapd_data *hapd,
 	if (buf == NULL)
 		return NULL;
 
+#ifdef CONFIG_SAE_PK
+#ifdef CONFIG_TESTING_OPTIONS
+	if (sta->sae->tmp)
+		sta->sae->tmp->omit_pk_elem = hapd->conf->sae_pk_omit;
+#endif /* CONFIG_TESTING_OPTIONS */
+#endif /* CONFIG_SAE_PK */
+
 	if (sae_write_confirm(sta->sae, buf) < 0) {
 		wpabuf_free(buf);
 		return NULL;
@@ -600,6 +607,15 @@ static int auth_sae_send_commit(struct hostapd_data *hapd,
 		status = WLAN_STATUS_SAE_HASH_TO_ELEMENT;
 	else
 		status = WLAN_STATUS_SUCCESS;
+#ifdef CONFIG_TESTING_OPTIONS
+	if (hapd->conf->sae_commit_status >= 0 &&
+	    hapd->conf->sae_commit_status != status) {
+		wpa_printf(MSG_INFO,
+			   "TESTING: Override SAE commit status code %u --> %d",
+			   status, hapd->conf->sae_commit_status);
+		status = hapd->conf->sae_commit_status;
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
 	reply_res = send_auth_reply(hapd, sta, sta->addr, bssid,
 				    WLAN_AUTH_SAE, 1,
 				    status, wpabuf_head(data),

src/common/sae.h

@@ -31,6 +31,9 @@ struct sae_pk {
 	struct crypto_ec_key *key;
 	int group;
 	struct wpabuf *pubkey; /* DER encoded subjectPublicKey */
+#ifdef CONFIG_TESTING_OPTIONS
+	struct crypto_ec_key *sign_key_override;
+#endif /* CONFIG_TESTING_OPTIONS */
 };
 
 
@@ -73,6 +76,9 @@ struct sae_temporary_data {
 	u8 ssid[32];
 	size_t ssid_len;
 	bool reject_group;
+#ifdef CONFIG_TESTING_OPTIONS
+	bool omit_pk_elem;
+#endif /* CONFIG_TESTING_OPTIONS */
 #endif /* CONFIG_SAE_PK */
 };
 

src/common/sae_pk.c

@@ -203,6 +203,9 @@ void sae_deinit_pk(struct sae_pk *pk)
 	if (pk) {
 		wpabuf_free(pk->m);
 		crypto_ec_key_deinit(pk->key);
+#ifdef CONFIG_TESTING_OPTIONS
+		crypto_ec_key_deinit(pk->sign_key_override);
+#endif /* CONFIG_TESTING_OPTIONS */
 		wpabuf_free(pk->pubkey);
 		os_free(pk);
 	}
@@ -213,9 +216,12 @@ struct sae_pk * sae_parse_pk(const char *val)
 {
 	struct sae_pk *pk;
 	const char *pos;
+#ifdef CONFIG_TESTING_OPTIONS
+	const char *pos2;
+#endif /* CONFIG_TESTING_OPTIONS */
 	size_t len;
 	unsigned char *der;
-	size_t der_len;
+	size_t der_len, b_len;
 
 	/* <m-as-hexdump>:<base64-encoded-DER-encoded-key> */
 
@@ -239,7 +245,15 @@ struct sae_pk * sae_parse_pk(const char *val)
 	}
 
 	pos++;
-	der = base64_decode(pos, os_strlen(pos), &der_len);
+	b_len = os_strlen(pos);
+#ifdef CONFIG_TESTING_OPTIONS
+	pos2 = os_strchr(pos, ':');
+	if (pos2) {
+		b_len = pos2 - pos;
+		pos2++;
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
+	der = base64_decode(pos, b_len, &der_len);
 	if (!der) {
 		wpa_printf(MSG_INFO, "SAE: Failed to base64 decode PK key");
 		goto fail;
@@ -254,6 +268,22 @@ struct sae_pk * sae_parse_pk(const char *val)
 	if (!pk->pubkey)
 		goto fail;
 
+#ifdef CONFIG_TESTING_OPTIONS
+	if (pos2) {
+		der = base64_decode(pos2, os_strlen(pos2), &der_len);
+		if (!der) {
+			wpa_printf(MSG_INFO,
+				   "SAE: Failed to base64 decode PK key");
+			goto fail;
+		}
+
+		pk->sign_key_override = crypto_ec_key_parse_priv(der, der_len);
+		bin_clear_free(der, der_len);
+		if (!pk->sign_key_override)
+			goto fail;
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
+
 	return pk;
 fail:
 	sae_deinit_pk(pk);
@@ -342,6 +372,7 @@ int sae_write_confirm_pk(struct sae_data *sae, struct wpabuf *buf)
 	const struct sae_pk *pk;
 	u8 hash[SAE_MAX_HASH_LEN];
 	size_t hash_len;
+	struct crypto_ec_key *key;
 
 	if (!tmp)
 		return -1;
@@ -350,6 +381,16 @@ int sae_write_confirm_pk(struct sae_data *sae, struct wpabuf *buf)
 	if (!pk)
 		return 0;
 
+	key = pk->key;
+#ifdef CONFIG_TESTING_OPTIONS
+	if (tmp->omit_pk_elem)
+		return 0;
+	if (pk->sign_key_override) {
+		wpa_printf(MSG_INFO, "TESTING: Override SAE-PK signing key");
+		key = pk->sign_key_override;
+	}
+#endif /* CONFIG_TESTING_OPTIONS */
+
 	if (tmp->kek_len != 32 && tmp->kek_len != 48 && tmp->kek_len != 64) {
 		wpa_printf(MSG_INFO, "SAE-PK: No KEK available for confirm");
 		return -1;
@@ -368,7 +409,7 @@ int sae_write_confirm_pk(struct sae_data *sae, struct wpabuf *buf)
 				 wpabuf_len(pk->m), wpabuf_head(pk->pubkey),
 				 wpabuf_len(pk->pubkey), hash) < 0)
 		goto fail;
-	sig = crypto_ec_key_sign(pk->key, hash, hash_len);
+	sig = crypto_ec_key_sign(key, hash, hash_len);
 	if (!sig)
 		goto fail;
 	wpa_hexdump_buf(MSG_DEBUG, "SAE-PK: KeyAuth = Sig_AP()", sig);