1 /*
2  * Wi-Fi Protected Setup - attribute building
3  * Copyright (c) 2008, Jouni Malinen <j@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 #ifdef CONFIG_WPS2
209 	u8 *len;
210 
211 #ifdef CONFIG_WPS_TESTING
212 	if (WPS_VERSION == 0x10)
213 		return 0;
214 #endif /* CONFIG_WPS_TESTING */
215 
216 	if (wpabuf_tailroom(msg) <
217 	    7 + 3 + (req_to_enroll ? 3 : 0) +
218 	    (auth_macs ? 2 + auth_macs_count * ETH_ALEN : 0))
219 		return -1;
220 	wpabuf_put_be16(msg, ATTR_VENDOR_EXT);
221 	len = wpabuf_put(msg, 2); /* to be filled */
222 	wpabuf_put_be24(msg, WPS_VENDOR_ID_WFA);
223 
224 	wpa_printf(MSG_DEBUG, "WPS:  * Version2 (0x%x)", WPS_VERSION);
225 	wpabuf_put_u8(msg, WFA_ELEM_VERSION2);
226 	wpabuf_put_u8(msg, 1);
227 	wpabuf_put_u8(msg, WPS_VERSION);
228 
229 	if (req_to_enroll) {
230 		wpa_printf(MSG_DEBUG, "WPS:  * Request to Enroll (1)");
231 		wpabuf_put_u8(msg, WFA_ELEM_REQUEST_TO_ENROLL);
232 		wpabuf_put_u8(msg, 1);
233 		wpabuf_put_u8(msg, 1);
234 	}
235 
236 	if (auth_macs && auth_macs_count) {
237 		size_t i;
238 		wpa_printf(MSG_DEBUG, "WPS:  * AuthorizedMACs (count=%d)",
239 			   (int) auth_macs_count);
240 		wpabuf_put_u8(msg, WFA_ELEM_AUTHORIZEDMACS);
241 		wpabuf_put_u8(msg, auth_macs_count * ETH_ALEN);
242 		wpabuf_put_data(msg, auth_macs, auth_macs_count * ETH_ALEN);
243 		for (i = 0; i < auth_macs_count; i++)
244 			wpa_printf(MSG_DEBUG, "WPS:    AuthorizedMAC: " MACSTR,
245 				   MAC2STR(&auth_macs[i * ETH_ALEN]));
246 	}
247 
248 	WPA_PUT_BE16(len, (u8 *) wpabuf_put(msg, 0) - len - 2);
249 #endif /* CONFIG_WPS2 */
250 
251 #ifdef CONFIG_WPS_TESTING
252 	if (WPS_VERSION > 0x20) {
253 		if (wpabuf_tailroom(msg) < 5)
254 			return -1;
255 		wpa_printf(MSG_DEBUG, "WPS:  * Extensibility Testing - extra "
256 			   "attribute");
257 		wpabuf_put_be16(msg, ATTR_EXTENSIBILITY_TEST);
258 		wpabuf_put_be16(msg, 1);
259 		wpabuf_put_u8(msg, 42);
260 	}
261 #endif /* CONFIG_WPS_TESTING */
262 	return 0;
263 }
264 
265 
266 int wps_build_msg_type(struct wpabuf *msg, enum wps_msg_type msg_type)
267 {
268 	wpa_printf(MSG_DEBUG, "WPS:  * Message Type (%d)", msg_type);
269 	wpabuf_put_be16(msg, ATTR_MSG_TYPE);
270 	wpabuf_put_be16(msg, 1);
271 	wpabuf_put_u8(msg, msg_type);
272 	return 0;
273 }
274 
275 
276 int wps_build_enrollee_nonce(struct wps_data *wps, struct wpabuf *msg)
277 {
278 	wpa_printf(MSG_DEBUG, "WPS:  * Enrollee Nonce");
279 	wpabuf_put_be16(msg, ATTR_ENROLLEE_NONCE);
280 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
281 	wpabuf_put_data(msg, wps->nonce_e, WPS_NONCE_LEN);
282 	return 0;
283 }
284 
285 
286 int wps_build_registrar_nonce(struct wps_data *wps, struct wpabuf *msg)
287 {
288 	wpa_printf(MSG_DEBUG, "WPS:  * Registrar Nonce");
289 	wpabuf_put_be16(msg, ATTR_REGISTRAR_NONCE);
290 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
291 	wpabuf_put_data(msg, wps->nonce_r, WPS_NONCE_LEN);
292 	return 0;
293 }
294 
295 
296 int wps_build_auth_type_flags(struct wps_data *wps, struct wpabuf *msg)
297 {
298 	u16 auth_types = WPS_AUTH_TYPES;
299 #ifdef CONFIG_WPS2
300 	auth_types &= ~WPS_AUTH_SHARED;
301 #endif /* CONFIG_WPS2 */
302 	wpa_printf(MSG_DEBUG, "WPS:  * Authentication Type Flags");
303 	wpabuf_put_be16(msg, ATTR_AUTH_TYPE_FLAGS);
304 	wpabuf_put_be16(msg, 2);
305 	wpabuf_put_be16(msg, auth_types);
306 	return 0;
307 }
308 
309 
310 int wps_build_encr_type_flags(struct wps_data *wps, struct wpabuf *msg)
311 {
312 	u16 encr_types = WPS_ENCR_TYPES;
313 #ifdef CONFIG_WPS2
314 	encr_types &= ~WPS_ENCR_WEP;
315 #endif /* CONFIG_WPS2 */
316 	wpa_printf(MSG_DEBUG, "WPS:  * Encryption Type Flags");
317 	wpabuf_put_be16(msg, ATTR_ENCR_TYPE_FLAGS);
318 	wpabuf_put_be16(msg, 2);
319 	wpabuf_put_be16(msg, encr_types);
320 	return 0;
321 }
322 
323 
324 int wps_build_conn_type_flags(struct wps_data *wps, struct wpabuf *msg)
325 {
326 	wpa_printf(MSG_DEBUG, "WPS:  * Connection Type Flags");
327 	wpabuf_put_be16(msg, ATTR_CONN_TYPE_FLAGS);
328 	wpabuf_put_be16(msg, 1);
329 	wpabuf_put_u8(msg, WPS_CONN_ESS);
330 	return 0;
331 }
332 
333 
334 int wps_build_assoc_state(struct wps_data *wps, struct wpabuf *msg)
335 {
336 	wpa_printf(MSG_DEBUG, "WPS:  * Association State");
337 	wpabuf_put_be16(msg, ATTR_ASSOC_STATE);
338 	wpabuf_put_be16(msg, 2);
339 	wpabuf_put_be16(msg, WPS_ASSOC_NOT_ASSOC);
340 	return 0;
341 }
342 
343 
344 int wps_build_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg)
345 {
346 	u8 hash[SHA256_MAC_LEN];
347 
348 	wpa_printf(MSG_DEBUG, "WPS:  * Key Wrap Authenticator");
349 	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, wpabuf_head(msg),
350 		    wpabuf_len(msg), hash);
351 
352 	wpabuf_put_be16(msg, ATTR_KEY_WRAP_AUTH);
353 	wpabuf_put_be16(msg, WPS_KWA_LEN);
354 	wpabuf_put_data(msg, hash, WPS_KWA_LEN);
355 	return 0;
356 }
357 
358 
359 int wps_build_encr_settings(struct wps_data *wps, struct wpabuf *msg,
360 			    struct wpabuf *plain)
361 {
362 	size_t pad_len;
363 	const size_t block_size = 16;
364 	u8 *iv, *data;
365 
366 	wpa_printf(MSG_DEBUG, "WPS:  * Encrypted Settings");
367 
368 	/* PKCS#5 v2.0 pad */
369 	pad_len = block_size - wpabuf_len(plain) % block_size;
370 	os_memset(wpabuf_put(plain, pad_len), pad_len, pad_len);
371 
372 	wpabuf_put_be16(msg, ATTR_ENCR_SETTINGS);
373 	wpabuf_put_be16(msg, block_size + wpabuf_len(plain));
374 
375 	iv = wpabuf_put(msg, block_size);
376 	if (random_get_bytes(iv, block_size) < 0)
377 		return -1;
378 
379 	data = wpabuf_put(msg, 0);
380 	wpabuf_put_buf(msg, plain);
381 	if (aes_128_cbc_encrypt(wps->keywrapkey, iv, data, wpabuf_len(plain)))
382 		return -1;
383 
384 	return 0;
385 }
386 
387 
388 #ifdef CONFIG_WPS_OOB
389 int wps_build_oob_dev_pw(struct wpabuf *msg, u16 dev_pw_id,
390 			 const struct wpabuf *pubkey, const u8 *dev_pw,
391 			 size_t dev_pw_len)
392 {
393 	size_t hash_len;
394 	const u8 *addr[1];
395 	u8 pubkey_hash[WPS_HASH_LEN];
396 
397 	wpa_printf(MSG_DEBUG, "WPS:  * OOB Device Password (dev_pw_id=%u)",
398 		   dev_pw_id);
399 	addr[0] = wpabuf_head(pubkey);
400 	hash_len = wpabuf_len(pubkey);
401 	sha256_vector(1, addr, &hash_len, pubkey_hash);
402 #ifdef CONFIG_WPS_TESTING
403 	if (wps_corrupt_pkhash) {
404 		wpa_hexdump(MSG_DEBUG, "WPS: Real Public Key Hash",
405 			    pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
406 		wpa_printf(MSG_INFO, "WPS: Testing - corrupt public key hash");
407 		pubkey_hash[WPS_OOB_PUBKEY_HASH_LEN - 2]++;
408 	}
409 #endif /* CONFIG_WPS_TESTING */
410 
411 	wpabuf_put_be16(msg, ATTR_OOB_DEVICE_PASSWORD);
412 	wpabuf_put_be16(msg, WPS_OOB_PUBKEY_HASH_LEN + 2 + dev_pw_len);
413 	wpa_hexdump(MSG_DEBUG, "WPS: Public Key Hash",
414 		    pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
415 	wpabuf_put_data(msg, pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
416 	wpabuf_put_be16(msg, dev_pw_id);
417 	if (dev_pw) {
418 		wpa_hexdump_key(MSG_DEBUG, "WPS: OOB Device Password",
419 				dev_pw, dev_pw_len);
420 		wpabuf_put_data(msg, dev_pw, dev_pw_len);
421 	}
422 
423 	return 0;
424 }
425 #endif /* CONFIG_WPS_OOB */
426 
427 
428 /* Encapsulate WPS IE data with one (or more, if needed) IE headers */
429 struct wpabuf * wps_ie_encapsulate(struct wpabuf *data)
430 {
431 	struct wpabuf *ie;
432 	const u8 *pos, *end;
433 
434 	ie = wpabuf_alloc(wpabuf_len(data) + 100);
435 	if (ie == NULL) {
436 		wpabuf_free(data);
437 		return NULL;
438 	}
439 
440 	pos = wpabuf_head(data);
441 	end = pos + wpabuf_len(data);
442 
443 	while (end > pos) {
444 		size_t frag_len = end - pos;
445 		if (frag_len > 251)
446 			frag_len = 251;
447 		wpabuf_put_u8(ie, WLAN_EID_VENDOR_SPECIFIC);
448 		wpabuf_put_u8(ie, 4 + frag_len);
449 		wpabuf_put_be32(ie, WPS_DEV_OUI_WFA);
450 		wpabuf_put_data(ie, pos, frag_len);
451 		pos += frag_len;
452 	}
453 
454 	wpabuf_free(data);
455 
456 	return ie;
457 }
458 
459 
460 int wps_build_mac_addr(struct wpabuf *msg, const u8 *addr)
461 {
462 	wpa_printf(MSG_DEBUG, "WPS:  * MAC Address (" MACSTR ")",
463 		   MAC2STR(addr));
464 	wpabuf_put_be16(msg, ATTR_MAC_ADDR);
465 	wpabuf_put_be16(msg, ETH_ALEN);
466 	wpabuf_put_data(msg, addr, ETH_ALEN);
467 	return 0;
468 }
469 
470 
471 int wps_build_rf_bands_attr(struct wpabuf *msg, u8 rf_bands)
472 {
473 	wpa_printf(MSG_DEBUG, "WPS:  * RF Bands (%x)", rf_bands);
474 	wpabuf_put_be16(msg, ATTR_RF_BANDS);
475 	wpabuf_put_be16(msg, 1);
476 	wpabuf_put_u8(msg, rf_bands);
477 	return 0;
478 }
479 
480 
481 int wps_build_ap_channel(struct wpabuf *msg, u16 ap_channel)
482 {
483 	wpa_printf(MSG_DEBUG, "WPS:  * AP Channel (%u)", ap_channel);
484 	wpabuf_put_be16(msg, ATTR_AP_CHANNEL);
485 	wpabuf_put_be16(msg, 2);
486 	wpabuf_put_be16(msg, ap_channel);
487 	return 0;
488 }
489