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1 /*
2  * Wi-Fi Protected Setup - attribute building
3  * Copyright (c) 2008, Jouni Malinen <j@w1.fi>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  *
9  * Alternatively, this software may be distributed under the terms of BSD
10  * license.
11  *
12  * See README and COPYING for more details.
13  */
14 
15 #include "includes.h"
16 
17 #include "common.h"
18 #include "crypto/dh_groups.h"
19 #include "crypto/sha256.h"
20 #include "crypto/aes_wrap.h"
21 #include "wps_i.h"
22 
23 
wps_build_public_key(struct wps_data * wps,struct wpabuf * msg)24 int wps_build_public_key(struct wps_data *wps, struct wpabuf *msg)
25 {
26 	struct wpabuf *pubkey;
27 
28 	wpa_printf(MSG_DEBUG, "WPS:  * Public Key");
29 	pubkey = dh_init(dh_groups_get(WPS_DH_GROUP), &wps->dh_privkey);
30 	pubkey = wpabuf_zeropad(pubkey, 192);
31 	if (pubkey == NULL) {
32 		wpa_printf(MSG_DEBUG, "WPS: Failed to initialize "
33 			   "Diffie-Hellman handshake");
34 		return -1;
35 	}
36 
37 	wpabuf_put_be16(msg, ATTR_PUBLIC_KEY);
38 	wpabuf_put_be16(msg, wpabuf_len(pubkey));
39 	wpabuf_put_buf(msg, pubkey);
40 
41 	if (wps->registrar) {
42 		wpabuf_free(wps->dh_pubkey_r);
43 		wps->dh_pubkey_r = pubkey;
44 	} else {
45 		wpabuf_free(wps->dh_pubkey_e);
46 		wps->dh_pubkey_e = pubkey;
47 	}
48 
49 	return 0;
50 }
51 
52 
wps_build_req_type(struct wpabuf * msg,enum wps_request_type type)53 int wps_build_req_type(struct wpabuf *msg, enum wps_request_type type)
54 {
55 	wpa_printf(MSG_DEBUG, "WPS:  * Request Type");
56 	wpabuf_put_be16(msg, ATTR_REQUEST_TYPE);
57 	wpabuf_put_be16(msg, 1);
58 	wpabuf_put_u8(msg, type);
59 	return 0;
60 }
61 
62 
wps_build_config_methods(struct wpabuf * msg,u16 methods)63 int wps_build_config_methods(struct wpabuf *msg, u16 methods)
64 {
65 	wpa_printf(MSG_DEBUG, "WPS:  * Config Methods (%x)", methods);
66 	wpabuf_put_be16(msg, ATTR_CONFIG_METHODS);
67 	wpabuf_put_be16(msg, 2);
68 	wpabuf_put_be16(msg, methods);
69 	return 0;
70 }
71 
72 
wps_build_uuid_e(struct wpabuf * msg,const u8 * uuid)73 int wps_build_uuid_e(struct wpabuf *msg, const u8 *uuid)
74 {
75 	wpa_printf(MSG_DEBUG, "WPS:  * UUID-E");
76 	wpabuf_put_be16(msg, ATTR_UUID_E);
77 	wpabuf_put_be16(msg, WPS_UUID_LEN);
78 	wpabuf_put_data(msg, uuid, WPS_UUID_LEN);
79 	return 0;
80 }
81 
82 
wps_build_dev_password_id(struct wpabuf * msg,u16 id)83 int wps_build_dev_password_id(struct wpabuf *msg, u16 id)
84 {
85 	wpa_printf(MSG_DEBUG, "WPS:  * Device Password ID (%d)", id);
86 	wpabuf_put_be16(msg, ATTR_DEV_PASSWORD_ID);
87 	wpabuf_put_be16(msg, 2);
88 	wpabuf_put_be16(msg, id);
89 	return 0;
90 }
91 
92 
wps_build_config_error(struct wpabuf * msg,u16 err)93 int wps_build_config_error(struct wpabuf *msg, u16 err)
94 {
95 	wpa_printf(MSG_DEBUG, "WPS:  * Configuration Error (%d)", err);
96 	wpabuf_put_be16(msg, ATTR_CONFIG_ERROR);
97 	wpabuf_put_be16(msg, 2);
98 	wpabuf_put_be16(msg, err);
99 	return 0;
100 }
101 
102 
wps_build_authenticator(struct wps_data * wps,struct wpabuf * msg)103 int wps_build_authenticator(struct wps_data *wps, struct wpabuf *msg)
104 {
105 	u8 hash[SHA256_MAC_LEN];
106 	const u8 *addr[2];
107 	size_t len[2];
108 
109 	if (wps->last_msg == NULL) {
110 		wpa_printf(MSG_DEBUG, "WPS: Last message not available for "
111 			   "building authenticator");
112 		return -1;
113 	}
114 
115 	/* Authenticator = HMAC-SHA256_AuthKey(M_prev || M_curr*)
116 	 * (M_curr* is M_curr without the Authenticator attribute)
117 	 */
118 	addr[0] = wpabuf_head(wps->last_msg);
119 	len[0] = wpabuf_len(wps->last_msg);
120 	addr[1] = wpabuf_head(msg);
121 	len[1] = wpabuf_len(msg);
122 	hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 2, addr, len, hash);
123 
124 	wpa_printf(MSG_DEBUG, "WPS:  * Authenticator");
125 	wpabuf_put_be16(msg, ATTR_AUTHENTICATOR);
126 	wpabuf_put_be16(msg, WPS_AUTHENTICATOR_LEN);
127 	wpabuf_put_data(msg, hash, WPS_AUTHENTICATOR_LEN);
128 
129 	return 0;
130 }
131 
132 
wps_build_version(struct wpabuf * msg)133 int wps_build_version(struct wpabuf *msg)
134 {
135 	wpa_printf(MSG_DEBUG, "WPS:  * Version");
136 	wpabuf_put_be16(msg, ATTR_VERSION);
137 	wpabuf_put_be16(msg, 1);
138 	wpabuf_put_u8(msg, WPS_VERSION);
139 	return 0;
140 }
141 
142 
wps_build_msg_type(struct wpabuf * msg,enum wps_msg_type msg_type)143 int wps_build_msg_type(struct wpabuf *msg, enum wps_msg_type msg_type)
144 {
145 	wpa_printf(MSG_DEBUG, "WPS:  * Message Type (%d)", msg_type);
146 	wpabuf_put_be16(msg, ATTR_MSG_TYPE);
147 	wpabuf_put_be16(msg, 1);
148 	wpabuf_put_u8(msg, msg_type);
149 	return 0;
150 }
151 
152 
wps_build_enrollee_nonce(struct wps_data * wps,struct wpabuf * msg)153 int wps_build_enrollee_nonce(struct wps_data *wps, struct wpabuf *msg)
154 {
155 	wpa_printf(MSG_DEBUG, "WPS:  * Enrollee Nonce");
156 	wpabuf_put_be16(msg, ATTR_ENROLLEE_NONCE);
157 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
158 	wpabuf_put_data(msg, wps->nonce_e, WPS_NONCE_LEN);
159 	return 0;
160 }
161 
162 
wps_build_registrar_nonce(struct wps_data * wps,struct wpabuf * msg)163 int wps_build_registrar_nonce(struct wps_data *wps, struct wpabuf *msg)
164 {
165 	wpa_printf(MSG_DEBUG, "WPS:  * Registrar Nonce");
166 	wpabuf_put_be16(msg, ATTR_REGISTRAR_NONCE);
167 	wpabuf_put_be16(msg, WPS_NONCE_LEN);
168 	wpabuf_put_data(msg, wps->nonce_r, WPS_NONCE_LEN);
169 	return 0;
170 }
171 
172 
wps_build_auth_type_flags(struct wps_data * wps,struct wpabuf * msg)173 int wps_build_auth_type_flags(struct wps_data *wps, struct wpabuf *msg)
174 {
175 	wpa_printf(MSG_DEBUG, "WPS:  * Authentication Type Flags");
176 	wpabuf_put_be16(msg, ATTR_AUTH_TYPE_FLAGS);
177 	wpabuf_put_be16(msg, 2);
178 	wpabuf_put_be16(msg, WPS_AUTH_TYPES);
179 	return 0;
180 }
181 
182 
wps_build_encr_type_flags(struct wps_data * wps,struct wpabuf * msg)183 int wps_build_encr_type_flags(struct wps_data *wps, struct wpabuf *msg)
184 {
185 	wpa_printf(MSG_DEBUG, "WPS:  * Encryption Type Flags");
186 	wpabuf_put_be16(msg, ATTR_ENCR_TYPE_FLAGS);
187 	wpabuf_put_be16(msg, 2);
188 	wpabuf_put_be16(msg, WPS_ENCR_TYPES);
189 	return 0;
190 }
191 
192 
wps_build_conn_type_flags(struct wps_data * wps,struct wpabuf * msg)193 int wps_build_conn_type_flags(struct wps_data *wps, struct wpabuf *msg)
194 {
195 	wpa_printf(MSG_DEBUG, "WPS:  * Connection Type Flags");
196 	wpabuf_put_be16(msg, ATTR_CONN_TYPE_FLAGS);
197 	wpabuf_put_be16(msg, 1);
198 	wpabuf_put_u8(msg, WPS_CONN_ESS);
199 	return 0;
200 }
201 
202 
wps_build_assoc_state(struct wps_data * wps,struct wpabuf * msg)203 int wps_build_assoc_state(struct wps_data *wps, struct wpabuf *msg)
204 {
205 	wpa_printf(MSG_DEBUG, "WPS:  * Association State");
206 	wpabuf_put_be16(msg, ATTR_ASSOC_STATE);
207 	wpabuf_put_be16(msg, 2);
208 	wpabuf_put_be16(msg, WPS_ASSOC_NOT_ASSOC);
209 	return 0;
210 }
211 
212 
wps_build_key_wrap_auth(struct wps_data * wps,struct wpabuf * msg)213 int wps_build_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg)
214 {
215 	u8 hash[SHA256_MAC_LEN];
216 
217 	wpa_printf(MSG_DEBUG, "WPS:  * Key Wrap Authenticator");
218 	hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, wpabuf_head(msg),
219 		    wpabuf_len(msg), hash);
220 
221 	wpabuf_put_be16(msg, ATTR_KEY_WRAP_AUTH);
222 	wpabuf_put_be16(msg, WPS_KWA_LEN);
223 	wpabuf_put_data(msg, hash, WPS_KWA_LEN);
224 	return 0;
225 }
226 
227 
wps_build_encr_settings(struct wps_data * wps,struct wpabuf * msg,struct wpabuf * plain)228 int wps_build_encr_settings(struct wps_data *wps, struct wpabuf *msg,
229 			    struct wpabuf *plain)
230 {
231 	size_t pad_len;
232 	const size_t block_size = 16;
233 	u8 *iv, *data;
234 
235 	wpa_printf(MSG_DEBUG, "WPS:  * Encrypted Settings");
236 
237 	/* PKCS#5 v2.0 pad */
238 	pad_len = block_size - wpabuf_len(plain) % block_size;
239 	os_memset(wpabuf_put(plain, pad_len), pad_len, pad_len);
240 
241 	wpabuf_put_be16(msg, ATTR_ENCR_SETTINGS);
242 	wpabuf_put_be16(msg, block_size + wpabuf_len(plain));
243 
244 	iv = wpabuf_put(msg, block_size);
245 	if (os_get_random(iv, block_size) < 0)
246 		return -1;
247 
248 	data = wpabuf_put(msg, 0);
249 	wpabuf_put_buf(msg, plain);
250 	if (aes_128_cbc_encrypt(wps->keywrapkey, iv, data, wpabuf_len(plain)))
251 		return -1;
252 
253 	return 0;
254 }
255