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      1 /*
      2  * Wi-Fi Protected Setup - attribute building
      3  * Copyright (c) 2008-2016, Jouni Malinen <j (at) w1.fi>
      4  *
      5  * This software may be distributed under the terms of the BSD license.
      6  * See README for more details.
      7  */
      8 
      9 #include "includes.h"
     10 
     11 #include "common.h"
     12 #include "crypto/aes_wrap.h"
     13 #include "crypto/crypto.h"
     14 #include "crypto/dh_group5.h"
     15 #include "crypto/sha256.h"
     16 #include "crypto/random.h"
     17 #include "common/ieee802_11_defs.h"
     18 #include "wps_i.h"
     19 
     20 
     21 int wps_build_public_key(struct wps_data *wps, struct wpabuf *msg)
     22 {
     23 	struct wpabuf *pubkey;
     24 
     25 	wpa_printf(MSG_DEBUG, "WPS:  * Public Key");
     26 	wpabuf_free(wps->dh_privkey);
     27 	wps->dh_privkey = NULL;
     28 	if (wps->dev_pw_id != DEV_PW_DEFAULT && wps->wps->dh_privkey &&
     29 	    wps->wps->dh_ctx) {
     30 		wpa_printf(MSG_DEBUG, "WPS: Using pre-configured DH keys");
     31 		if (wps->wps->dh_pubkey == NULL) {
     32 			wpa_printf(MSG_DEBUG,
     33 				   "WPS: wps->wps->dh_pubkey == NULL");
     34 			return -1;
     35 		}
     36 		wps->dh_privkey = wpabuf_dup(wps->wps->dh_privkey);
     37 		wps->dh_ctx = wps->wps->dh_ctx;
     38 		wps->wps->dh_ctx = NULL;
     39 		pubkey = wpabuf_dup(wps->wps->dh_pubkey);
     40 #ifdef CONFIG_WPS_NFC
     41 	} else if ((wps->dev_pw_id >= 0x10 ||
     42 		    wps->dev_pw_id == DEV_PW_NFC_CONNECTION_HANDOVER) &&
     43 		   (wps->wps->ap ||
     44 		    (wps->wps->ap_nfc_dh_pubkey &&
     45 		     wps->wps->ap_nfc_dev_pw_id ==
     46 		     DEV_PW_NFC_CONNECTION_HANDOVER &&
     47 		     wps->dev_pw_id == DEV_PW_NFC_CONNECTION_HANDOVER)) &&
     48 		   (wps->dev_pw_id == wps->wps->ap_nfc_dev_pw_id ||
     49 		    wps->wps->ap_nfc_dh_pubkey)) {
     50 		wpa_printf(MSG_DEBUG, "WPS: Using NFC password token DH keys");
     51 		if (wps->wps->ap_nfc_dh_privkey == NULL) {
     52 			wpa_printf(MSG_DEBUG,
     53 				   "WPS: wps->wps->ap_nfc_dh_privkey == NULL");
     54 			return -1;
     55 		}
     56 		if (wps->wps->ap_nfc_dh_pubkey == NULL) {
     57 			wpa_printf(MSG_DEBUG,
     58 				   "WPS: wps->wps->ap_nfc_dh_pubkey == NULL");
     59 			return -1;
     60 		}
     61 		wps->dh_privkey = wpabuf_dup(wps->wps->ap_nfc_dh_privkey);
     62 		pubkey = wpabuf_dup(wps->wps->ap_nfc_dh_pubkey);
     63 		wps->dh_ctx = dh5_init_fixed(wps->dh_privkey, pubkey);
     64 #endif /* CONFIG_WPS_NFC */
     65 	} else {
     66 		wpa_printf(MSG_DEBUG, "WPS: Generate new DH keys");
     67 		dh5_free(wps->dh_ctx);
     68 		wps->dh_ctx = dh5_init(&wps->dh_privkey, &pubkey);
     69 		pubkey = wpabuf_zeropad(pubkey, 192);
     70 	}
     71 	if (wps->dh_ctx == NULL || wps->dh_privkey == NULL || pubkey == NULL) {
     72 		wpa_printf(MSG_DEBUG, "WPS: Failed to initialize "
     73 			   "Diffie-Hellman handshake");
     74 		wpabuf_free(pubkey);
     75 		return -1;
     76 	}
     77 	wpa_hexdump_buf_key(MSG_DEBUG, "WPS: DH Private Key", wps->dh_privkey);
     78 	wpa_hexdump_buf(MSG_DEBUG, "WPS: DH own Public Key", pubkey);
     79 
     80 	wpabuf_put_be16(msg, ATTR_PUBLIC_KEY);
     81 	wpabuf_put_be16(msg, wpabuf_len(pubkey));
     82 	wpabuf_put_buf(msg, pubkey);
     83 
     84 	if (wps->registrar) {
     85 		wpabuf_free(wps->dh_pubkey_r);
     86 		wps->dh_pubkey_r = pubkey;
     87 	} else {
     88 		wpabuf_free(wps->dh_pubkey_e);
     89 		wps->dh_pubkey_e = pubkey;
     90 	}
     91 
     92 	return 0;
     93 }
     94 
     95 
     96 int wps_build_req_type(struct wpabuf *msg, enum wps_request_type type)
     97 {
     98 	wpa_printf(MSG_DEBUG, "WPS:  * Request Type");
     99 	wpabuf_put_be16(msg, ATTR_REQUEST_TYPE);
    100 	wpabuf_put_be16(msg, 1);
    101 	wpabuf_put_u8(msg, type);
    102 	return 0;
    103 }
    104 
    105 
    106 int wps_build_resp_type(struct wpabuf *msg, enum wps_response_type type)
    107 {
    108 	wpa_printf(MSG_DEBUG, "WPS:  * Response Type (%d)", type);
    109 	wpabuf_put_be16(msg, ATTR_RESPONSE_TYPE);
    110 	wpabuf_put_be16(msg, 1);
    111 	wpabuf_put_u8(msg, type);
    112 	return 0;
    113 }
    114 
    115 
    116 int wps_build_config_methods(struct wpabuf *msg, u16 methods)
    117 {
    118 	wpa_printf(MSG_DEBUG, "WPS:  * Config Methods (%x)", methods);
    119 	wpabuf_put_be16(msg, ATTR_CONFIG_METHODS);
    120 	wpabuf_put_be16(msg, 2);
    121 	wpabuf_put_be16(msg, methods);
    122 	return 0;
    123 }
    124 
    125 
    126 int wps_build_uuid_e(struct wpabuf *msg, const u8 *uuid)
    127 {
    128 	if (wpabuf_tailroom(msg) < 4 + WPS_UUID_LEN)
    129 		return -1;
    130 	wpa_printf(MSG_DEBUG, "WPS:  * UUID-E");
    131 	wpabuf_put_be16(msg, ATTR_UUID_E);
    132 	wpabuf_put_be16(msg, WPS_UUID_LEN);
    133 	wpabuf_put_data(msg, uuid, WPS_UUID_LEN);
    134 	return 0;
    135 }
    136 
    137 
    138 int wps_build_dev_password_id(struct wpabuf *msg, u16 id)
    139 {
    140 	wpa_printf(MSG_DEBUG, "WPS:  * Device Password ID (%d)", id);
    141 	wpabuf_put_be16(msg, ATTR_DEV_PASSWORD_ID);
    142 	wpabuf_put_be16(msg, 2);
    143 	wpabuf_put_be16(msg, id);
    144 	return 0;
    145 }
    146 
    147 
    148 int wps_build_config_error(struct wpabuf *msg, u16 err)
    149 {
    150 	wpa_printf(MSG_DEBUG, "WPS:  * Configuration Error (%d)", err);
    151 	wpabuf_put_be16(msg, ATTR_CONFIG_ERROR);
    152 	wpabuf_put_be16(msg, 2);
    153 	wpabuf_put_be16(msg, err);
    154 	return 0;
    155 }
    156 
    157 
    158 int wps_build_authenticator(struct wps_data *wps, struct wpabuf *msg)
    159 {
    160 	u8 hash[SHA256_MAC_LEN];
    161 	const u8 *addr[2];
    162 	size_t len[2];
    163 
    164 	if (wps->last_msg == NULL) {
    165 		wpa_printf(MSG_DEBUG, "WPS: Last message not available for "
    166 			   "building authenticator");
    167 		return -1;
    168 	}
    169 
    170 	/* Authenticator = HMAC-SHA256_AuthKey(M_prev || M_curr*)
    171 	 * (M_curr* is M_curr without the Authenticator attribute)
    172 	 */
    173 	addr[0] = wpabuf_head(wps->last_msg);
    174 	len[0] = wpabuf_len(wps->last_msg);
    175 	addr[1] = wpabuf_head(msg);
    176 	len[1] = wpabuf_len(msg);
    177 	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 2, addr, len, hash);
    178 
    179 	wpa_printf(MSG_DEBUG, "WPS:  * Authenticator");
    180 	wpabuf_put_be16(msg, ATTR_AUTHENTICATOR);
    181 	wpabuf_put_be16(msg, WPS_AUTHENTICATOR_LEN);
    182 	wpabuf_put_data(msg, hash, WPS_AUTHENTICATOR_LEN);
    183 
    184 	return 0;
    185 }
    186 
    187 
    188 int wps_build_version(struct wpabuf *msg)
    189 {
    190 	/*
    191 	 * Note: This attribute is deprecated and set to hardcoded 0x10 for
    192 	 * backwards compatibility reasons. The real version negotiation is
    193 	 * done with Version2.
    194 	 */
    195 	if (wpabuf_tailroom(msg) < 5)
    196 		return -1;
    197 	wpa_printf(MSG_DEBUG, "WPS:  * Version (hardcoded 0x10)");
    198 	wpabuf_put_be16(msg, ATTR_VERSION);
    199 	wpabuf_put_be16(msg, 1);
    200 	wpabuf_put_u8(msg, 0x10);
    201 	return 0;
    202 }
    203 
    204 
    205 int wps_build_wfa_ext(struct wpabuf *msg, int req_to_enroll,
    206 		      const u8 *auth_macs, size_t auth_macs_count)
    207 {
    208 	u8 *len;
    209 
    210 #ifdef CONFIG_WPS_TESTING
    211 	if (WPS_VERSION == 0x10)
    212 		return 0;
    213 #endif /* CONFIG_WPS_TESTING */
    214 
    215 	if (wpabuf_tailroom(msg) <
    216 	    7 + 3 + (req_to_enroll ? 3 : 0) +
    217 	    (auth_macs ? 2 + auth_macs_count * ETH_ALEN : 0))
    218 		return -1;
    219 	wpabuf_put_be16(msg, ATTR_VENDOR_EXT);
    220 	len = wpabuf_put(msg, 2); /* to be filled */
    221 	wpabuf_put_be24(msg, WPS_VENDOR_ID_WFA);
    222 
    223 	wpa_printf(MSG_DEBUG, "WPS:  * Version2 (0x%x)", WPS_VERSION);
    224 	wpabuf_put_u8(msg, WFA_ELEM_VERSION2);
    225 	wpabuf_put_u8(msg, 1);
    226 	wpabuf_put_u8(msg, WPS_VERSION);
    227 
    228 	if (req_to_enroll) {
    229 		wpa_printf(MSG_DEBUG, "WPS:  * Request to Enroll (1)");
    230 		wpabuf_put_u8(msg, WFA_ELEM_REQUEST_TO_ENROLL);
    231 		wpabuf_put_u8(msg, 1);
    232 		wpabuf_put_u8(msg, 1);
    233 	}
    234 
    235 	if (auth_macs && auth_macs_count) {
    236 		size_t i;
    237 		wpa_printf(MSG_DEBUG, "WPS:  * AuthorizedMACs (count=%d)",
    238 			   (int) auth_macs_count);
    239 		wpabuf_put_u8(msg, WFA_ELEM_AUTHORIZEDMACS);
    240 		wpabuf_put_u8(msg, auth_macs_count * ETH_ALEN);
    241 		wpabuf_put_data(msg, auth_macs, auth_macs_count * ETH_ALEN);
    242 		for (i = 0; i < auth_macs_count; i++)
    243 			wpa_printf(MSG_DEBUG, "WPS:    AuthorizedMAC: " MACSTR,
    244 				   MAC2STR(&auth_macs[i * ETH_ALEN]));
    245 	}
    246 
    247 	WPA_PUT_BE16(len, (u8 *) wpabuf_put(msg, 0) - len - 2);
    248 
    249 #ifdef CONFIG_WPS_TESTING
    250 	if (WPS_VERSION > 0x20) {
    251 		if (wpabuf_tailroom(msg) < 5)
    252 			return -1;
    253 		wpa_printf(MSG_DEBUG, "WPS:  * Extensibility Testing - extra "
    254 			   "attribute");
    255 		wpabuf_put_be16(msg, ATTR_EXTENSIBILITY_TEST);
    256 		wpabuf_put_be16(msg, 1);
    257 		wpabuf_put_u8(msg, 42);
    258 	}
    259 #endif /* CONFIG_WPS_TESTING */
    260 	return 0;
    261 }
    262 
    263 
    264 int wps_build_msg_type(struct wpabuf *msg, enum wps_msg_type msg_type)
    265 {
    266 	wpa_printf(MSG_DEBUG, "WPS:  * Message Type (%d)", msg_type);
    267 	wpabuf_put_be16(msg, ATTR_MSG_TYPE);
    268 	wpabuf_put_be16(msg, 1);
    269 	wpabuf_put_u8(msg, msg_type);
    270 	return 0;
    271 }
    272 
    273 
    274 int wps_build_enrollee_nonce(struct wps_data *wps, struct wpabuf *msg)
    275 {
    276 	wpa_printf(MSG_DEBUG, "WPS:  * Enrollee Nonce");
    277 	wpabuf_put_be16(msg, ATTR_ENROLLEE_NONCE);
    278 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
    279 	wpabuf_put_data(msg, wps->nonce_e, WPS_NONCE_LEN);
    280 	return 0;
    281 }
    282 
    283 
    284 int wps_build_registrar_nonce(struct wps_data *wps, struct wpabuf *msg)
    285 {
    286 	wpa_printf(MSG_DEBUG, "WPS:  * Registrar Nonce");
    287 	wpabuf_put_be16(msg, ATTR_REGISTRAR_NONCE);
    288 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
    289 	wpabuf_put_data(msg, wps->nonce_r, WPS_NONCE_LEN);
    290 	return 0;
    291 }
    292 
    293 
    294 int wps_build_auth_type_flags(struct wps_data *wps, struct wpabuf *msg)
    295 {
    296 	u16 auth_types = WPS_AUTH_TYPES;
    297 	/* WPA/WPA2-Enterprise enrollment not supported through WPS */
    298 	auth_types &= ~WPS_AUTH_WPA;
    299 	auth_types &= ~WPS_AUTH_WPA2;
    300 	auth_types &= ~WPS_AUTH_SHARED;
    301 #ifdef CONFIG_WPS_TESTING
    302 	if (wps_force_auth_types_in_use) {
    303 		wpa_printf(MSG_DEBUG,
    304 			   "WPS: Testing - replace auth type 0x%x with 0x%x",
    305 			   auth_types, wps_force_auth_types);
    306 		auth_types = wps_force_auth_types;
    307 	}
    308 #endif /* CONFIG_WPS_TESTING */
    309 	wpa_printf(MSG_DEBUG, "WPS:  * Authentication Type Flags (0x%x)",
    310 		   auth_types);
    311 	wpabuf_put_be16(msg, ATTR_AUTH_TYPE_FLAGS);
    312 	wpabuf_put_be16(msg, 2);
    313 	wpabuf_put_be16(msg, auth_types);
    314 	return 0;
    315 }
    316 
    317 
    318 int wps_build_encr_type_flags(struct wps_data *wps, struct wpabuf *msg)
    319 {
    320 	u16 encr_types = WPS_ENCR_TYPES;
    321 	encr_types &= ~WPS_ENCR_WEP;
    322 #ifdef CONFIG_WPS_TESTING
    323 	if (wps_force_encr_types_in_use) {
    324 		wpa_printf(MSG_DEBUG,
    325 			   "WPS: Testing - replace encr type 0x%x with 0x%x",
    326 			   encr_types, wps_force_encr_types);
    327 		encr_types = wps_force_encr_types;
    328 	}
    329 #endif /* CONFIG_WPS_TESTING */
    330 	wpa_printf(MSG_DEBUG, "WPS:  * Encryption Type Flags (0x%x)",
    331 		   encr_types);
    332 	wpabuf_put_be16(msg, ATTR_ENCR_TYPE_FLAGS);
    333 	wpabuf_put_be16(msg, 2);
    334 	wpabuf_put_be16(msg, encr_types);
    335 	return 0;
    336 }
    337 
    338 
    339 int wps_build_conn_type_flags(struct wps_data *wps, struct wpabuf *msg)
    340 {
    341 	wpa_printf(MSG_DEBUG, "WPS:  * Connection Type Flags");
    342 	wpabuf_put_be16(msg, ATTR_CONN_TYPE_FLAGS);
    343 	wpabuf_put_be16(msg, 1);
    344 	wpabuf_put_u8(msg, WPS_CONN_ESS);
    345 	return 0;
    346 }
    347 
    348 
    349 int wps_build_assoc_state(struct wps_data *wps, struct wpabuf *msg)
    350 {
    351 	wpa_printf(MSG_DEBUG, "WPS:  * Association State");
    352 	wpabuf_put_be16(msg, ATTR_ASSOC_STATE);
    353 	wpabuf_put_be16(msg, 2);
    354 	wpabuf_put_be16(msg, WPS_ASSOC_NOT_ASSOC);
    355 	return 0;
    356 }
    357 
    358 
    359 int wps_build_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg)
    360 {
    361 	u8 hash[SHA256_MAC_LEN];
    362 
    363 	wpa_printf(MSG_DEBUG, "WPS:  * Key Wrap Authenticator");
    364 	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, wpabuf_head(msg),
    365 		    wpabuf_len(msg), hash);
    366 
    367 	wpabuf_put_be16(msg, ATTR_KEY_WRAP_AUTH);
    368 	wpabuf_put_be16(msg, WPS_KWA_LEN);
    369 	wpabuf_put_data(msg, hash, WPS_KWA_LEN);
    370 	return 0;
    371 }
    372 
    373 
    374 int wps_build_encr_settings(struct wps_data *wps, struct wpabuf *msg,
    375 			    struct wpabuf *plain)
    376 {
    377 	size_t pad_len;
    378 	const size_t block_size = 16;
    379 	u8 *iv, *data;
    380 
    381 	wpa_printf(MSG_DEBUG, "WPS:  * Encrypted Settings");
    382 
    383 	/* PKCS#5 v2.0 pad */
    384 	pad_len = block_size - wpabuf_len(plain) % block_size;
    385 	os_memset(wpabuf_put(plain, pad_len), pad_len, pad_len);
    386 
    387 	wpabuf_put_be16(msg, ATTR_ENCR_SETTINGS);
    388 	wpabuf_put_be16(msg, block_size + wpabuf_len(plain));
    389 
    390 	iv = wpabuf_put(msg, block_size);
    391 	if (random_get_bytes(iv, block_size) < 0)
    392 		return -1;
    393 
    394 	data = wpabuf_put(msg, 0);
    395 	wpabuf_put_buf(msg, plain);
    396 	if (aes_128_cbc_encrypt(wps->keywrapkey, iv, data, wpabuf_len(plain)))
    397 		return -1;
    398 
    399 	return 0;
    400 }
    401 
    402 
    403 #ifdef CONFIG_WPS_OOB
    404 int wps_build_oob_dev_pw(struct wpabuf *msg, u16 dev_pw_id,
    405 			 const struct wpabuf *pubkey, const u8 *dev_pw,
    406 			 size_t dev_pw_len)
    407 {
    408 	size_t hash_len;
    409 	const u8 *addr[1];
    410 	u8 pubkey_hash[WPS_HASH_LEN];
    411 
    412 	wpa_printf(MSG_DEBUG, "WPS:  * OOB Device Password (dev_pw_id=%u)",
    413 		   dev_pw_id);
    414 	addr[0] = wpabuf_head(pubkey);
    415 	hash_len = wpabuf_len(pubkey);
    416 	sha256_vector(1, addr, &hash_len, pubkey_hash);
    417 #ifdef CONFIG_WPS_TESTING
    418 	if (wps_corrupt_pkhash) {
    419 		wpa_hexdump(MSG_DEBUG, "WPS: Real Public Key Hash",
    420 			    pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
    421 		wpa_printf(MSG_INFO, "WPS: Testing - corrupt public key hash");
    422 		pubkey_hash[WPS_OOB_PUBKEY_HASH_LEN - 2]++;
    423 	}
    424 #endif /* CONFIG_WPS_TESTING */
    425 
    426 	wpabuf_put_be16(msg, ATTR_OOB_DEVICE_PASSWORD);
    427 	wpabuf_put_be16(msg, WPS_OOB_PUBKEY_HASH_LEN + 2 + dev_pw_len);
    428 	wpa_hexdump(MSG_DEBUG, "WPS: Public Key Hash",
    429 		    pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
    430 	wpabuf_put_data(msg, pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
    431 	wpabuf_put_be16(msg, dev_pw_id);
    432 	if (dev_pw) {
    433 		wpa_hexdump_key(MSG_DEBUG, "WPS: OOB Device Password",
    434 				dev_pw, dev_pw_len);
    435 		wpabuf_put_data(msg, dev_pw, dev_pw_len);
    436 	}
    437 
    438 	return 0;
    439 }
    440 #endif /* CONFIG_WPS_OOB */
    441 
    442 
    443 /* Encapsulate WPS IE data with one (or more, if needed) IE headers */
    444 struct wpabuf * wps_ie_encapsulate(struct wpabuf *data)
    445 {
    446 	struct wpabuf *ie;
    447 	const u8 *pos, *end;
    448 
    449 	ie = wpabuf_alloc(wpabuf_len(data) + 100);
    450 	if (ie == NULL) {
    451 		wpabuf_free(data);
    452 		return NULL;
    453 	}
    454 
    455 	pos = wpabuf_head(data);
    456 	end = pos + wpabuf_len(data);
    457 
    458 	while (end > pos) {
    459 		size_t frag_len = end - pos;
    460 		if (frag_len > 251)
    461 			frag_len = 251;
    462 		wpabuf_put_u8(ie, WLAN_EID_VENDOR_SPECIFIC);
    463 		wpabuf_put_u8(ie, 4 + frag_len);
    464 		wpabuf_put_be32(ie, WPS_DEV_OUI_WFA);
    465 		wpabuf_put_data(ie, pos, frag_len);
    466 		pos += frag_len;
    467 	}
    468 
    469 	wpabuf_free(data);
    470 
    471 	return ie;
    472 }
    473 
    474 
    475 int wps_build_mac_addr(struct wpabuf *msg, const u8 *addr)
    476 {
    477 	wpa_printf(MSG_DEBUG, "WPS:  * MAC Address (" MACSTR ")",
    478 		   MAC2STR(addr));
    479 	wpabuf_put_be16(msg, ATTR_MAC_ADDR);
    480 	wpabuf_put_be16(msg, ETH_ALEN);
    481 	wpabuf_put_data(msg, addr, ETH_ALEN);
    482 	return 0;
    483 }
    484 
    485 
    486 int wps_build_rf_bands_attr(struct wpabuf *msg, u8 rf_bands)
    487 {
    488 	wpa_printf(MSG_DEBUG, "WPS:  * RF Bands (%x)", rf_bands);
    489 	wpabuf_put_be16(msg, ATTR_RF_BANDS);
    490 	wpabuf_put_be16(msg, 1);
    491 	wpabuf_put_u8(msg, rf_bands);
    492 	return 0;
    493 }
    494 
    495 
    496 int wps_build_ap_channel(struct wpabuf *msg, u16 ap_channel)
    497 {
    498 	wpa_printf(MSG_DEBUG, "WPS:  * AP Channel (%u)", ap_channel);
    499 	wpabuf_put_be16(msg, ATTR_AP_CHANNEL);
    500 	wpabuf_put_be16(msg, 2);
    501 	wpabuf_put_be16(msg, ap_channel);
    502 	return 0;
    503 }
    504