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      1 /*
      2  * Wi-Fi Protected Setup - attribute building
      3  * Copyright (c) 2008, 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 && wps->wps->ap &&
     42 		   wps->dev_pw_id == wps->wps->ap_nfc_dev_pw_id) {
     43 		wpa_printf(MSG_DEBUG, "WPS: Using NFC password token DH keys");
     44 		if (wps->wps->ap_nfc_dh_privkey == NULL) {
     45 			wpa_printf(MSG_DEBUG,
     46 				   "WPS: wps->wps->ap_nfc_dh_privkey == NULL");
     47 			return -1;
     48 		}
     49 		if (wps->wps->ap_nfc_dh_pubkey == NULL) {
     50 			wpa_printf(MSG_DEBUG,
     51 				   "WPS: wps->wps->ap_nfc_dh_pubkey == NULL");
     52 			return -1;
     53 		}
     54 		wps->dh_privkey = wpabuf_dup(wps->wps->ap_nfc_dh_privkey);
     55 		pubkey = wpabuf_dup(wps->wps->ap_nfc_dh_pubkey);
     56 		wps->dh_ctx = dh5_init_fixed(wps->dh_privkey, pubkey);
     57 #endif /* CONFIG_WPS_NFC */
     58 	} else {
     59 		wpa_printf(MSG_DEBUG, "WPS: Generate new DH keys");
     60 		dh5_free(wps->dh_ctx);
     61 		wps->dh_ctx = dh5_init(&wps->dh_privkey, &pubkey);
     62 		pubkey = wpabuf_zeropad(pubkey, 192);
     63 	}
     64 	if (wps->dh_ctx == NULL || wps->dh_privkey == NULL || pubkey == NULL) {
     65 		wpa_printf(MSG_DEBUG, "WPS: Failed to initialize "
     66 			   "Diffie-Hellman handshake");
     67 		wpabuf_free(pubkey);
     68 		return -1;
     69 	}
     70 	wpa_hexdump_buf_key(MSG_DEBUG, "WPS: DH Private Key", wps->dh_privkey);
     71 	wpa_hexdump_buf(MSG_DEBUG, "WPS: DH own Public Key", pubkey);
     72 
     73 	wpabuf_put_be16(msg, ATTR_PUBLIC_KEY);
     74 	wpabuf_put_be16(msg, wpabuf_len(pubkey));
     75 	wpabuf_put_buf(msg, pubkey);
     76 
     77 	if (wps->registrar) {
     78 		wpabuf_free(wps->dh_pubkey_r);
     79 		wps->dh_pubkey_r = pubkey;
     80 	} else {
     81 		wpabuf_free(wps->dh_pubkey_e);
     82 		wps->dh_pubkey_e = pubkey;
     83 	}
     84 
     85 	return 0;
     86 }
     87 
     88 
     89 int wps_build_req_type(struct wpabuf *msg, enum wps_request_type type)
     90 {
     91 	wpa_printf(MSG_DEBUG, "WPS:  * Request Type");
     92 	wpabuf_put_be16(msg, ATTR_REQUEST_TYPE);
     93 	wpabuf_put_be16(msg, 1);
     94 	wpabuf_put_u8(msg, type);
     95 	return 0;
     96 }
     97 
     98 
     99 int wps_build_resp_type(struct wpabuf *msg, enum wps_response_type type)
    100 {
    101 	wpa_printf(MSG_DEBUG, "WPS:  * Response Type (%d)", type);
    102 	wpabuf_put_be16(msg, ATTR_RESPONSE_TYPE);
    103 	wpabuf_put_be16(msg, 1);
    104 	wpabuf_put_u8(msg, type);
    105 	return 0;
    106 }
    107 
    108 
    109 int wps_build_config_methods(struct wpabuf *msg, u16 methods)
    110 {
    111 	wpa_printf(MSG_DEBUG, "WPS:  * Config Methods (%x)", methods);
    112 	wpabuf_put_be16(msg, ATTR_CONFIG_METHODS);
    113 	wpabuf_put_be16(msg, 2);
    114 	wpabuf_put_be16(msg, methods);
    115 	return 0;
    116 }
    117 
    118 
    119 int wps_build_uuid_e(struct wpabuf *msg, const u8 *uuid)
    120 {
    121 	wpa_printf(MSG_DEBUG, "WPS:  * UUID-E");
    122 	wpabuf_put_be16(msg, ATTR_UUID_E);
    123 	wpabuf_put_be16(msg, WPS_UUID_LEN);
    124 	wpabuf_put_data(msg, uuid, WPS_UUID_LEN);
    125 	return 0;
    126 }
    127 
    128 
    129 int wps_build_dev_password_id(struct wpabuf *msg, u16 id)
    130 {
    131 	wpa_printf(MSG_DEBUG, "WPS:  * Device Password ID (%d)", id);
    132 	wpabuf_put_be16(msg, ATTR_DEV_PASSWORD_ID);
    133 	wpabuf_put_be16(msg, 2);
    134 	wpabuf_put_be16(msg, id);
    135 	return 0;
    136 }
    137 
    138 
    139 int wps_build_config_error(struct wpabuf *msg, u16 err)
    140 {
    141 	wpa_printf(MSG_DEBUG, "WPS:  * Configuration Error (%d)", err);
    142 	wpabuf_put_be16(msg, ATTR_CONFIG_ERROR);
    143 	wpabuf_put_be16(msg, 2);
    144 	wpabuf_put_be16(msg, err);
    145 	return 0;
    146 }
    147 
    148 
    149 int wps_build_authenticator(struct wps_data *wps, struct wpabuf *msg)
    150 {
    151 	u8 hash[SHA256_MAC_LEN];
    152 	const u8 *addr[2];
    153 	size_t len[2];
    154 
    155 	if (wps->last_msg == NULL) {
    156 		wpa_printf(MSG_DEBUG, "WPS: Last message not available for "
    157 			   "building authenticator");
    158 		return -1;
    159 	}
    160 
    161 	/* Authenticator = HMAC-SHA256_AuthKey(M_prev || M_curr*)
    162 	 * (M_curr* is M_curr without the Authenticator attribute)
    163 	 */
    164 	addr[0] = wpabuf_head(wps->last_msg);
    165 	len[0] = wpabuf_len(wps->last_msg);
    166 	addr[1] = wpabuf_head(msg);
    167 	len[1] = wpabuf_len(msg);
    168 	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 2, addr, len, hash);
    169 
    170 	wpa_printf(MSG_DEBUG, "WPS:  * Authenticator");
    171 	wpabuf_put_be16(msg, ATTR_AUTHENTICATOR);
    172 	wpabuf_put_be16(msg, WPS_AUTHENTICATOR_LEN);
    173 	wpabuf_put_data(msg, hash, WPS_AUTHENTICATOR_LEN);
    174 
    175 	return 0;
    176 }
    177 
    178 
    179 int wps_build_version(struct wpabuf *msg)
    180 {
    181 	/*
    182 	 * Note: This attribute is deprecated and set to hardcoded 0x10 for
    183 	 * backwards compatibility reasons. The real version negotiation is
    184 	 * done with Version2.
    185 	 */
    186 	wpa_printf(MSG_DEBUG, "WPS:  * Version (hardcoded 0x10)");
    187 	wpabuf_put_be16(msg, ATTR_VERSION);
    188 	wpabuf_put_be16(msg, 1);
    189 	wpabuf_put_u8(msg, 0x10);
    190 	return 0;
    191 }
    192 
    193 
    194 int wps_build_wfa_ext(struct wpabuf *msg, int req_to_enroll,
    195 		      const u8 *auth_macs, size_t auth_macs_count)
    196 {
    197 #ifdef CONFIG_WPS2
    198 	u8 *len;
    199 
    200 	wpabuf_put_be16(msg, ATTR_VENDOR_EXT);
    201 	len = wpabuf_put(msg, 2); /* to be filled */
    202 	wpabuf_put_be24(msg, WPS_VENDOR_ID_WFA);
    203 
    204 	wpa_printf(MSG_DEBUG, "WPS:  * Version2 (0x%x)", WPS_VERSION);
    205 	wpabuf_put_u8(msg, WFA_ELEM_VERSION2);
    206 	wpabuf_put_u8(msg, 1);
    207 	wpabuf_put_u8(msg, WPS_VERSION);
    208 
    209 	if (req_to_enroll) {
    210 		wpa_printf(MSG_DEBUG, "WPS:  * Request to Enroll (1)");
    211 		wpabuf_put_u8(msg, WFA_ELEM_REQUEST_TO_ENROLL);
    212 		wpabuf_put_u8(msg, 1);
    213 		wpabuf_put_u8(msg, 1);
    214 	}
    215 
    216 	if (auth_macs && auth_macs_count) {
    217 		size_t i;
    218 		wpa_printf(MSG_DEBUG, "WPS:  * AuthorizedMACs (count=%d)",
    219 			   (int) auth_macs_count);
    220 		wpabuf_put_u8(msg, WFA_ELEM_AUTHORIZEDMACS);
    221 		wpabuf_put_u8(msg, auth_macs_count * ETH_ALEN);
    222 		wpabuf_put_data(msg, auth_macs, auth_macs_count * ETH_ALEN);
    223 		for (i = 0; i < auth_macs_count; i++)
    224 			wpa_printf(MSG_DEBUG, "WPS:    AuthorizedMAC: " MACSTR,
    225 				   MAC2STR(&auth_macs[i * ETH_ALEN]));
    226 	}
    227 
    228 	WPA_PUT_BE16(len, (u8 *) wpabuf_put(msg, 0) - len - 2);
    229 #endif /* CONFIG_WPS2 */
    230 
    231 #ifdef CONFIG_WPS_TESTING
    232 	if (WPS_VERSION > 0x20) {
    233 		wpa_printf(MSG_DEBUG, "WPS:  * Extensibility Testing - extra "
    234 			   "attribute");
    235 		wpabuf_put_be16(msg, ATTR_EXTENSIBILITY_TEST);
    236 		wpabuf_put_be16(msg, 1);
    237 		wpabuf_put_u8(msg, 42);
    238 	}
    239 #endif /* CONFIG_WPS_TESTING */
    240 	return 0;
    241 }
    242 
    243 
    244 int wps_build_msg_type(struct wpabuf *msg, enum wps_msg_type msg_type)
    245 {
    246 	wpa_printf(MSG_DEBUG, "WPS:  * Message Type (%d)", msg_type);
    247 	wpabuf_put_be16(msg, ATTR_MSG_TYPE);
    248 	wpabuf_put_be16(msg, 1);
    249 	wpabuf_put_u8(msg, msg_type);
    250 	return 0;
    251 }
    252 
    253 
    254 int wps_build_enrollee_nonce(struct wps_data *wps, struct wpabuf *msg)
    255 {
    256 	wpa_printf(MSG_DEBUG, "WPS:  * Enrollee Nonce");
    257 	wpabuf_put_be16(msg, ATTR_ENROLLEE_NONCE);
    258 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
    259 	wpabuf_put_data(msg, wps->nonce_e, WPS_NONCE_LEN);
    260 	return 0;
    261 }
    262 
    263 
    264 int wps_build_registrar_nonce(struct wps_data *wps, struct wpabuf *msg)
    265 {
    266 	wpa_printf(MSG_DEBUG, "WPS:  * Registrar Nonce");
    267 	wpabuf_put_be16(msg, ATTR_REGISTRAR_NONCE);
    268 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
    269 	wpabuf_put_data(msg, wps->nonce_r, WPS_NONCE_LEN);
    270 	return 0;
    271 }
    272 
    273 
    274 int wps_build_auth_type_flags(struct wps_data *wps, struct wpabuf *msg)
    275 {
    276 	u16 auth_types = WPS_AUTH_TYPES;
    277 #ifdef CONFIG_WPS2
    278 	auth_types &= ~WPS_AUTH_SHARED;
    279 #endif /* CONFIG_WPS2 */
    280 	wpa_printf(MSG_DEBUG, "WPS:  * Authentication Type Flags");
    281 	wpabuf_put_be16(msg, ATTR_AUTH_TYPE_FLAGS);
    282 	wpabuf_put_be16(msg, 2);
    283 	wpabuf_put_be16(msg, auth_types);
    284 	return 0;
    285 }
    286 
    287 
    288 int wps_build_encr_type_flags(struct wps_data *wps, struct wpabuf *msg)
    289 {
    290 	u16 encr_types = WPS_ENCR_TYPES;
    291 #ifdef CONFIG_WPS2
    292 	encr_types &= ~WPS_ENCR_WEP;
    293 #endif /* CONFIG_WPS2 */
    294 	wpa_printf(MSG_DEBUG, "WPS:  * Encryption Type Flags");
    295 	wpabuf_put_be16(msg, ATTR_ENCR_TYPE_FLAGS);
    296 	wpabuf_put_be16(msg, 2);
    297 	wpabuf_put_be16(msg, encr_types);
    298 	return 0;
    299 }
    300 
    301 
    302 int wps_build_conn_type_flags(struct wps_data *wps, struct wpabuf *msg)
    303 {
    304 	wpa_printf(MSG_DEBUG, "WPS:  * Connection Type Flags");
    305 	wpabuf_put_be16(msg, ATTR_CONN_TYPE_FLAGS);
    306 	wpabuf_put_be16(msg, 1);
    307 	wpabuf_put_u8(msg, WPS_CONN_ESS);
    308 	return 0;
    309 }
    310 
    311 
    312 int wps_build_assoc_state(struct wps_data *wps, struct wpabuf *msg)
    313 {
    314 	wpa_printf(MSG_DEBUG, "WPS:  * Association State");
    315 	wpabuf_put_be16(msg, ATTR_ASSOC_STATE);
    316 	wpabuf_put_be16(msg, 2);
    317 	wpabuf_put_be16(msg, WPS_ASSOC_NOT_ASSOC);
    318 	return 0;
    319 }
    320 
    321 
    322 int wps_build_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg)
    323 {
    324 	u8 hash[SHA256_MAC_LEN];
    325 
    326 	wpa_printf(MSG_DEBUG, "WPS:  * Key Wrap Authenticator");
    327 	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, wpabuf_head(msg),
    328 		    wpabuf_len(msg), hash);
    329 
    330 	wpabuf_put_be16(msg, ATTR_KEY_WRAP_AUTH);
    331 	wpabuf_put_be16(msg, WPS_KWA_LEN);
    332 	wpabuf_put_data(msg, hash, WPS_KWA_LEN);
    333 	return 0;
    334 }
    335 
    336 
    337 int wps_build_encr_settings(struct wps_data *wps, struct wpabuf *msg,
    338 			    struct wpabuf *plain)
    339 {
    340 	size_t pad_len;
    341 	const size_t block_size = 16;
    342 	u8 *iv, *data;
    343 
    344 	wpa_printf(MSG_DEBUG, "WPS:  * Encrypted Settings");
    345 
    346 	/* PKCS#5 v2.0 pad */
    347 	pad_len = block_size - wpabuf_len(plain) % block_size;
    348 	os_memset(wpabuf_put(plain, pad_len), pad_len, pad_len);
    349 
    350 	wpabuf_put_be16(msg, ATTR_ENCR_SETTINGS);
    351 	wpabuf_put_be16(msg, block_size + wpabuf_len(plain));
    352 
    353 	iv = wpabuf_put(msg, block_size);
    354 	if (random_get_bytes(iv, block_size) < 0)
    355 		return -1;
    356 
    357 	data = wpabuf_put(msg, 0);
    358 	wpabuf_put_buf(msg, plain);
    359 	if (aes_128_cbc_encrypt(wps->keywrapkey, iv, data, wpabuf_len(plain)))
    360 		return -1;
    361 
    362 	return 0;
    363 }
    364 
    365 
    366 #ifdef CONFIG_WPS_OOB
    367 int wps_build_oob_dev_pw(struct wpabuf *msg, u16 dev_pw_id,
    368 			 const struct wpabuf *pubkey, const u8 *dev_pw,
    369 			 size_t dev_pw_len)
    370 {
    371 	size_t hash_len;
    372 	const u8 *addr[1];
    373 	u8 pubkey_hash[WPS_HASH_LEN];
    374 
    375 	addr[0] = wpabuf_head(pubkey);
    376 	hash_len = wpabuf_len(pubkey);
    377 	sha256_vector(1, addr, &hash_len, pubkey_hash);
    378 
    379 	wpabuf_put_be16(msg, ATTR_OOB_DEVICE_PASSWORD);
    380 	wpabuf_put_be16(msg, WPS_OOB_PUBKEY_HASH_LEN + 2 + dev_pw_len);
    381 	wpabuf_put_data(msg, pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
    382 	wpabuf_put_be16(msg, dev_pw_id);
    383 	wpabuf_put_data(msg, dev_pw, dev_pw_len);
    384 
    385 	return 0;
    386 }
    387 #endif /* CONFIG_WPS_OOB */
    388 
    389 
    390 /* Encapsulate WPS IE data with one (or more, if needed) IE headers */
    391 struct wpabuf * wps_ie_encapsulate(struct wpabuf *data)
    392 {
    393 	struct wpabuf *ie;
    394 	const u8 *pos, *end;
    395 
    396 	ie = wpabuf_alloc(wpabuf_len(data) + 100);
    397 	if (ie == NULL) {
    398 		wpabuf_free(data);
    399 		return NULL;
    400 	}
    401 
    402 	pos = wpabuf_head(data);
    403 	end = pos + wpabuf_len(data);
    404 
    405 	while (end > pos) {
    406 		size_t frag_len = end - pos;
    407 		if (frag_len > 251)
    408 			frag_len = 251;
    409 		wpabuf_put_u8(ie, WLAN_EID_VENDOR_SPECIFIC);
    410 		wpabuf_put_u8(ie, 4 + frag_len);
    411 		wpabuf_put_be32(ie, WPS_DEV_OUI_WFA);
    412 		wpabuf_put_data(ie, pos, frag_len);
    413 		pos += frag_len;
    414 	}
    415 
    416 	wpabuf_free(data);
    417 
    418 	return ie;
    419 }
    420 
    421 
    422 int wps_build_mac_addr(struct wpabuf *msg, const u8 *addr)
    423 {
    424 	wpa_printf(MSG_DEBUG, "WPS:  * MAC Address (" MACSTR ")",
    425 		   MAC2STR(addr));
    426 	wpabuf_put_be16(msg, ATTR_MAC_ADDR);
    427 	wpabuf_put_be16(msg, ETH_ALEN);
    428 	wpabuf_put_data(msg, addr, ETH_ALEN);
    429 	return 0;
    430 }
    431