wps_attr_build.c revision 04949598a23f501be6eec21697465fd46a28840a 
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
21int 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	if (wps->dev_pw_id != DEV_PW_DEFAULT && wps->wps->dh_privkey) {
28		wpa_printf(MSG_DEBUG, "WPS: Using pre-configured DH keys");
29		wps->dh_privkey = wpabuf_dup(wps->wps->dh_privkey);
30		wps->dh_ctx = wps->wps->dh_ctx;
31		wps->wps->dh_ctx = NULL;
32		pubkey = wpabuf_dup(wps->wps->dh_pubkey);
33#ifdef CONFIG_WPS_NFC
34	} else if (wps->dev_pw_id >= 0x10 && wps->wps->ap &&
35		   wps->dev_pw_id == wps->wps->ap_nfc_dev_pw_id) {
36		wpa_printf(MSG_DEBUG, "WPS: Using NFC password token DH keys");
37		wps->dh_privkey = wpabuf_dup(wps->wps->ap_nfc_dh_privkey);
38		pubkey = wpabuf_dup(wps->wps->ap_nfc_dh_pubkey);
39		wps->dh_ctx = dh5_init_fixed(wps->dh_privkey, pubkey);
40#endif /* CONFIG_WPS_NFC */
41	} else {
42		wpa_printf(MSG_DEBUG, "WPS: Generate new DH keys");
43		wps->dh_privkey = NULL;
44		dh5_free(wps->dh_ctx);
45		wps->dh_ctx = dh5_init(&wps->dh_privkey, &pubkey);
46		pubkey = wpabuf_zeropad(pubkey, 192);
47	}
48	if (wps->dh_ctx == NULL || wps->dh_privkey == NULL || pubkey == NULL) {
49		wpa_printf(MSG_DEBUG, "WPS: Failed to initialize "
50			   "Diffie-Hellman handshake");
51		wpabuf_free(pubkey);
52		return -1;
53	}
54	wpa_hexdump_buf_key(MSG_DEBUG, "WPS: DH Private Key", wps->dh_privkey);
55	wpa_hexdump_buf(MSG_DEBUG, "WPS: DH own Public Key", pubkey);
56
57	wpabuf_put_be16(msg, ATTR_PUBLIC_KEY);
58	wpabuf_put_be16(msg, wpabuf_len(pubkey));
59	wpabuf_put_buf(msg, pubkey);
60
61	if (wps->registrar) {
62		wpabuf_free(wps->dh_pubkey_r);
63		wps->dh_pubkey_r = pubkey;
64	} else {
65		wpabuf_free(wps->dh_pubkey_e);
66		wps->dh_pubkey_e = pubkey;
67	}
68
69	return 0;
70}
71
72
73int wps_build_req_type(struct wpabuf *msg, enum wps_request_type type)
74{
75	wpa_printf(MSG_DEBUG, "WPS:  * Request Type");
76	wpabuf_put_be16(msg, ATTR_REQUEST_TYPE);
77	wpabuf_put_be16(msg, 1);
78	wpabuf_put_u8(msg, type);
79	return 0;
80}
81
82
83int wps_build_resp_type(struct wpabuf *msg, enum wps_response_type type)
84{
85	wpa_printf(MSG_DEBUG, "WPS:  * Response Type (%d)", type);
86	wpabuf_put_be16(msg, ATTR_RESPONSE_TYPE);
87	wpabuf_put_be16(msg, 1);
88	wpabuf_put_u8(msg, type);
89	return 0;
90}
91
92
93int wps_build_config_methods(struct wpabuf *msg, u16 methods)
94{
95	wpa_printf(MSG_DEBUG, "WPS:  * Config Methods (%x)", methods);
96	wpabuf_put_be16(msg, ATTR_CONFIG_METHODS);
97	wpabuf_put_be16(msg, 2);
98	wpabuf_put_be16(msg, methods);
99	return 0;
100}
101
102
103int wps_build_uuid_e(struct wpabuf *msg, const u8 *uuid)
104{
105	wpa_printf(MSG_DEBUG, "WPS:  * UUID-E");
106	wpabuf_put_be16(msg, ATTR_UUID_E);
107	wpabuf_put_be16(msg, WPS_UUID_LEN);
108	wpabuf_put_data(msg, uuid, WPS_UUID_LEN);
109	return 0;
110}
111
112
113int wps_build_dev_password_id(struct wpabuf *msg, u16 id)
114{
115	wpa_printf(MSG_DEBUG, "WPS:  * Device Password ID (%d)", id);
116	wpabuf_put_be16(msg, ATTR_DEV_PASSWORD_ID);
117	wpabuf_put_be16(msg, 2);
118	wpabuf_put_be16(msg, id);
119	return 0;
120}
121
122
123int wps_build_config_error(struct wpabuf *msg, u16 err)
124{
125	wpa_printf(MSG_DEBUG, "WPS:  * Configuration Error (%d)", err);
126	wpabuf_put_be16(msg, ATTR_CONFIG_ERROR);
127	wpabuf_put_be16(msg, 2);
128	wpabuf_put_be16(msg, err);
129	return 0;
130}
131
132
133int wps_build_authenticator(struct wps_data *wps, struct wpabuf *msg)
134{
135	u8 hash[SHA256_MAC_LEN];
136	const u8 *addr[2];
137	size_t len[2];
138
139	if (wps->last_msg == NULL) {
140		wpa_printf(MSG_DEBUG, "WPS: Last message not available for "
141			   "building authenticator");
142		return -1;
143	}
144
145	/* Authenticator = HMAC-SHA256_AuthKey(M_prev || M_curr*)
146	 * (M_curr* is M_curr without the Authenticator attribute)
147	 */
148	addr[0] = wpabuf_head(wps->last_msg);
149	len[0] = wpabuf_len(wps->last_msg);
150	addr[1] = wpabuf_head(msg);
151	len[1] = wpabuf_len(msg);
152	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 2, addr, len, hash);
153
154	wpa_printf(MSG_DEBUG, "WPS:  * Authenticator");
155	wpabuf_put_be16(msg, ATTR_AUTHENTICATOR);
156	wpabuf_put_be16(msg, WPS_AUTHENTICATOR_LEN);
157	wpabuf_put_data(msg, hash, WPS_AUTHENTICATOR_LEN);
158
159	return 0;
160}
161
162
163int wps_build_version(struct wpabuf *msg)
164{
165	/*
166	 * Note: This attribute is deprecated and set to hardcoded 0x10 for
167	 * backwards compatibility reasons. The real version negotiation is
168	 * done with Version2.
169	 */
170	wpa_printf(MSG_DEBUG, "WPS:  * Version (hardcoded 0x10)");
171	wpabuf_put_be16(msg, ATTR_VERSION);
172	wpabuf_put_be16(msg, 1);
173	wpabuf_put_u8(msg, 0x10);
174	return 0;
175}
176
177
178int wps_build_wfa_ext(struct wpabuf *msg, int req_to_enroll,
179		      const u8 *auth_macs, size_t auth_macs_count)
180{
181#ifdef CONFIG_WPS2
182	u8 *len;
183
184	wpabuf_put_be16(msg, ATTR_VENDOR_EXT);
185	len = wpabuf_put(msg, 2); /* to be filled */
186	wpabuf_put_be24(msg, WPS_VENDOR_ID_WFA);
187
188	wpa_printf(MSG_DEBUG, "WPS:  * Version2 (0x%x)", WPS_VERSION);
189	wpabuf_put_u8(msg, WFA_ELEM_VERSION2);
190	wpabuf_put_u8(msg, 1);
191	wpabuf_put_u8(msg, WPS_VERSION);
192
193	if (req_to_enroll) {
194		wpa_printf(MSG_DEBUG, "WPS:  * Request to Enroll (1)");
195		wpabuf_put_u8(msg, WFA_ELEM_REQUEST_TO_ENROLL);
196		wpabuf_put_u8(msg, 1);
197		wpabuf_put_u8(msg, 1);
198	}
199
200	if (auth_macs && auth_macs_count) {
201		size_t i;
202		wpa_printf(MSG_DEBUG, "WPS:  * AuthorizedMACs (count=%d)",
203			   (int) auth_macs_count);
204		wpabuf_put_u8(msg, WFA_ELEM_AUTHORIZEDMACS);
205		wpabuf_put_u8(msg, auth_macs_count * ETH_ALEN);
206		wpabuf_put_data(msg, auth_macs, auth_macs_count * ETH_ALEN);
207		for (i = 0; i < auth_macs_count; i++)
208			wpa_printf(MSG_DEBUG, "WPS:    AuthorizedMAC: " MACSTR,
209				   MAC2STR(&auth_macs[i * ETH_ALEN]));
210	}
211
212	WPA_PUT_BE16(len, (u8 *) wpabuf_put(msg, 0) - len - 2);
213#endif /* CONFIG_WPS2 */
214
215#ifdef CONFIG_WPS_TESTING
216	if (WPS_VERSION > 0x20) {
217		wpa_printf(MSG_DEBUG, "WPS:  * Extensibility Testing - extra "
218			   "attribute");
219		wpabuf_put_be16(msg, ATTR_EXTENSIBILITY_TEST);
220		wpabuf_put_be16(msg, 1);
221		wpabuf_put_u8(msg, 42);
222	}
223#endif /* CONFIG_WPS_TESTING */
224	return 0;
225}
226
227
228int wps_build_msg_type(struct wpabuf *msg, enum wps_msg_type msg_type)
229{
230	wpa_printf(MSG_DEBUG, "WPS:  * Message Type (%d)", msg_type);
231	wpabuf_put_be16(msg, ATTR_MSG_TYPE);
232	wpabuf_put_be16(msg, 1);
233	wpabuf_put_u8(msg, msg_type);
234	return 0;
235}
236
237
238int wps_build_enrollee_nonce(struct wps_data *wps, struct wpabuf *msg)
239{
240	wpa_printf(MSG_DEBUG, "WPS:  * Enrollee Nonce");
241	wpabuf_put_be16(msg, ATTR_ENROLLEE_NONCE);
242	wpabuf_put_be16(msg, WPS_NONCE_LEN);
243	wpabuf_put_data(msg, wps->nonce_e, WPS_NONCE_LEN);
244	return 0;
245}
246
247
248int wps_build_registrar_nonce(struct wps_data *wps, struct wpabuf *msg)
249{
250	wpa_printf(MSG_DEBUG, "WPS:  * Registrar Nonce");
251	wpabuf_put_be16(msg, ATTR_REGISTRAR_NONCE);
252	wpabuf_put_be16(msg, WPS_NONCE_LEN);
253	wpabuf_put_data(msg, wps->nonce_r, WPS_NONCE_LEN);
254	return 0;
255}
256
257
258int wps_build_auth_type_flags(struct wps_data *wps, struct wpabuf *msg)
259{
260	u16 auth_types = WPS_AUTH_TYPES;
261#ifdef CONFIG_WPS2
262	auth_types &= ~WPS_AUTH_SHARED;
263#endif /* CONFIG_WPS2 */
264	wpa_printf(MSG_DEBUG, "WPS:  * Authentication Type Flags");
265	wpabuf_put_be16(msg, ATTR_AUTH_TYPE_FLAGS);
266	wpabuf_put_be16(msg, 2);
267	wpabuf_put_be16(msg, auth_types);
268	return 0;
269}
270
271
272int wps_build_encr_type_flags(struct wps_data *wps, struct wpabuf *msg)
273{
274	u16 encr_types = WPS_ENCR_TYPES;
275#ifdef CONFIG_WPS2
276	encr_types &= ~WPS_ENCR_WEP;
277#endif /* CONFIG_WPS2 */
278	wpa_printf(MSG_DEBUG, "WPS:  * Encryption Type Flags");
279	wpabuf_put_be16(msg, ATTR_ENCR_TYPE_FLAGS);
280	wpabuf_put_be16(msg, 2);
281	wpabuf_put_be16(msg, encr_types);
282	return 0;
283}
284
285
286int wps_build_conn_type_flags(struct wps_data *wps, struct wpabuf *msg)
287{
288	wpa_printf(MSG_DEBUG, "WPS:  * Connection Type Flags");
289	wpabuf_put_be16(msg, ATTR_CONN_TYPE_FLAGS);
290	wpabuf_put_be16(msg, 1);
291	wpabuf_put_u8(msg, WPS_CONN_ESS);
292	return 0;
293}
294
295
296int wps_build_assoc_state(struct wps_data *wps, struct wpabuf *msg)
297{
298	wpa_printf(MSG_DEBUG, "WPS:  * Association State");
299	wpabuf_put_be16(msg, ATTR_ASSOC_STATE);
300	wpabuf_put_be16(msg, 2);
301	wpabuf_put_be16(msg, WPS_ASSOC_NOT_ASSOC);
302	return 0;
303}
304
305
306int wps_build_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg)
307{
308	u8 hash[SHA256_MAC_LEN];
309
310	wpa_printf(MSG_DEBUG, "WPS:  * Key Wrap Authenticator");
311	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, wpabuf_head(msg),
312		    wpabuf_len(msg), hash);
313
314	wpabuf_put_be16(msg, ATTR_KEY_WRAP_AUTH);
315	wpabuf_put_be16(msg, WPS_KWA_LEN);
316	wpabuf_put_data(msg, hash, WPS_KWA_LEN);
317	return 0;
318}
319
320
321int wps_build_encr_settings(struct wps_data *wps, struct wpabuf *msg,
322			    struct wpabuf *plain)
323{
324	size_t pad_len;
325	const size_t block_size = 16;
326	u8 *iv, *data;
327
328	wpa_printf(MSG_DEBUG, "WPS:  * Encrypted Settings");
329
330	/* PKCS#5 v2.0 pad */
331	pad_len = block_size - wpabuf_len(plain) % block_size;
332	os_memset(wpabuf_put(plain, pad_len), pad_len, pad_len);
333
334	wpabuf_put_be16(msg, ATTR_ENCR_SETTINGS);
335	wpabuf_put_be16(msg, block_size + wpabuf_len(plain));
336
337	iv = wpabuf_put(msg, block_size);
338	if (random_get_bytes(iv, block_size) < 0)
339		return -1;
340
341	data = wpabuf_put(msg, 0);
342	wpabuf_put_buf(msg, plain);
343	if (aes_128_cbc_encrypt(wps->keywrapkey, iv, data, wpabuf_len(plain)))
344		return -1;
345
346	return 0;
347}
348
349
350#ifdef CONFIG_WPS_OOB
351int wps_build_oob_dev_pw(struct wpabuf *msg, u16 dev_pw_id,
352			 const struct wpabuf *pubkey, const u8 *dev_pw,
353			 size_t dev_pw_len)
354{
355	size_t hash_len;
356	const u8 *addr[1];
357	u8 pubkey_hash[WPS_HASH_LEN];
358
359	addr[0] = wpabuf_head(pubkey);
360	hash_len = wpabuf_len(pubkey);
361	sha256_vector(1, addr, &hash_len, pubkey_hash);
362
363	wpabuf_put_be16(msg, ATTR_OOB_DEVICE_PASSWORD);
364	wpabuf_put_be16(msg, WPS_OOB_PUBKEY_HASH_LEN + 2 + dev_pw_len);
365	wpabuf_put_data(msg, pubkey_hash, WPS_OOB_PUBKEY_HASH_LEN);
366	wpabuf_put_be16(msg, dev_pw_id);
367	wpabuf_put_data(msg, dev_pw, dev_pw_len);
368
369	return 0;
370}
371
372
373int wps_build_oob_dev_password(struct wpabuf *msg, struct wps_context *wps)
374{
375	u8 dev_password_bin[WPS_OOB_DEVICE_PASSWORD_LEN];
376
377	wpa_printf(MSG_DEBUG, "WPS:  * OOB Device Password");
378
379	if (os_get_random((u8 *) &wps->oob_dev_pw_id, sizeof(u16)) < 0) {
380		wpa_printf(MSG_ERROR, "WPS: device password id "
381			   "generation error");
382		return -1;
383	}
384	wps->oob_dev_pw_id |= 0x0010;
385
386	if (random_get_bytes(dev_password_bin, WPS_OOB_DEVICE_PASSWORD_LEN) <
387	    0) {
388		wpa_printf(MSG_ERROR, "WPS: OOB device password "
389			   "generation error");
390		return -1;
391	}
392
393	wpa_snprintf_hex_uppercase(
394		wpabuf_put(wps->oob_conf.dev_password,
395			   wpabuf_size(wps->oob_conf.dev_password)),
396		wpabuf_size(wps->oob_conf.dev_password),
397		dev_password_bin, WPS_OOB_DEVICE_PASSWORD_LEN);
398
399	return wps_build_oob_dev_pw(msg, wps->oob_dev_pw_id, wps->dh_pubkey,
400				    dev_password_bin,
401				    WPS_OOB_DEVICE_PASSWORD_LEN);
402}
403#endif /* CONFIG_WPS_OOB */
404
405
406/* Encapsulate WPS IE data with one (or more, if needed) IE headers */
407struct wpabuf * wps_ie_encapsulate(struct wpabuf *data)
408{
409	struct wpabuf *ie;
410	const u8 *pos, *end;
411
412	ie = wpabuf_alloc(wpabuf_len(data) + 100);
413	if (ie == NULL) {
414		wpabuf_free(data);
415		return NULL;
416	}
417
418	pos = wpabuf_head(data);
419	end = pos + wpabuf_len(data);
420
421	while (end > pos) {
422		size_t frag_len = end - pos;
423		if (frag_len > 251)
424			frag_len = 251;
425		wpabuf_put_u8(ie, WLAN_EID_VENDOR_SPECIFIC);
426		wpabuf_put_u8(ie, 4 + frag_len);
427		wpabuf_put_be32(ie, WPS_DEV_OUI_WFA);
428		wpabuf_put_data(ie, pos, frag_len);
429		pos += frag_len;
430	}
431
432	wpabuf_free(data);
433
434	return ie;
435}
436