1 /*
2 * Wi-Fi Protected Setup - attribute processing
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/sha256.h"
13 #include "wps_i.h"
14
15
wps_process_authenticator(struct wps_data * wps,const u8 * authenticator,const struct wpabuf * msg)16 int wps_process_authenticator(struct wps_data *wps, const u8 *authenticator,
17 const struct wpabuf *msg)
18 {
19 u8 hash[SHA256_MAC_LEN];
20 const u8 *addr[2];
21 size_t len[2];
22
23 if (authenticator == NULL) {
24 wpa_printf(MSG_DEBUG, "WPS: No Authenticator attribute "
25 "included");
26 return -1;
27 }
28
29 if (wps->last_msg == NULL) {
30 wpa_printf(MSG_DEBUG, "WPS: Last message not available for "
31 "validating authenticator");
32 return -1;
33 }
34
35 /* Authenticator = HMAC-SHA256_AuthKey(M_prev || M_curr*)
36 * (M_curr* is M_curr without the Authenticator attribute)
37 */
38 addr[0] = wpabuf_head(wps->last_msg);
39 len[0] = wpabuf_len(wps->last_msg);
40 addr[1] = wpabuf_head(msg);
41 len[1] = wpabuf_len(msg) - 4 - WPS_AUTHENTICATOR_LEN;
42 hmac_sha256_vector(wps->authkey, WPS_AUTHKEY_LEN, 2, addr, len, hash);
43
44 if (os_memcmp_const(hash, authenticator, WPS_AUTHENTICATOR_LEN) != 0) {
45 wpa_printf(MSG_DEBUG, "WPS: Incorrect Authenticator");
46 return -1;
47 }
48
49 return 0;
50 }
51
52
wps_process_key_wrap_auth(struct wps_data * wps,struct wpabuf * msg,const u8 * key_wrap_auth)53 int wps_process_key_wrap_auth(struct wps_data *wps, struct wpabuf *msg,
54 const u8 *key_wrap_auth)
55 {
56 u8 hash[SHA256_MAC_LEN];
57 const u8 *head;
58 size_t len;
59
60 if (key_wrap_auth == NULL) {
61 wpa_printf(MSG_DEBUG, "WPS: No KWA in decrypted attribute");
62 return -1;
63 }
64
65 head = wpabuf_head(msg);
66 len = wpabuf_len(msg) - 4 - WPS_KWA_LEN;
67 if (head + len != key_wrap_auth - 4) {
68 wpa_printf(MSG_DEBUG, "WPS: KWA not in the end of the "
69 "decrypted attribute");
70 return -1;
71 }
72
73 hmac_sha256(wps->authkey, WPS_AUTHKEY_LEN, head, len, hash);
74 if (os_memcmp_const(hash, key_wrap_auth, WPS_KWA_LEN) != 0) {
75 wpa_printf(MSG_DEBUG, "WPS: Invalid KWA");
76 return -1;
77 }
78
79 return 0;
80 }
81
82
wps_process_cred_network_idx(struct wps_credential * cred,const u8 * idx)83 static int wps_process_cred_network_idx(struct wps_credential *cred,
84 const u8 *idx)
85 {
86 if (idx == NULL) {
87 wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
88 "Network Index");
89 return -1;
90 }
91
92 wpa_printf(MSG_DEBUG, "WPS: Network Index: %d", *idx);
93
94 return 0;
95 }
96
97
wps_process_cred_ssid(struct wps_credential * cred,const u8 * ssid,size_t ssid_len)98 static int wps_process_cred_ssid(struct wps_credential *cred, const u8 *ssid,
99 size_t ssid_len)
100 {
101 if (ssid == NULL) {
102 wpa_printf(MSG_DEBUG, "WPS: Credential did not include SSID");
103 return -1;
104 }
105
106 /* Remove zero-padding since some Registrar implementations seem to use
107 * hardcoded 32-octet length for this attribute */
108 while (ssid_len > 0 && ssid[ssid_len - 1] == 0)
109 ssid_len--;
110
111 wpa_hexdump_ascii(MSG_DEBUG, "WPS: SSID", ssid, ssid_len);
112 if (ssid_len <= sizeof(cred->ssid)) {
113 os_memcpy(cred->ssid, ssid, ssid_len);
114 cred->ssid_len = ssid_len;
115 }
116
117 return 0;
118 }
119
120
wps_process_cred_auth_type(struct wps_credential * cred,const u8 * auth_type)121 static int wps_process_cred_auth_type(struct wps_credential *cred,
122 const u8 *auth_type)
123 {
124 if (auth_type == NULL) {
125 wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
126 "Authentication Type");
127 return -1;
128 }
129
130 cred->auth_type = WPA_GET_BE16(auth_type);
131 wpa_printf(MSG_DEBUG, "WPS: Authentication Type: 0x%x",
132 cred->auth_type);
133
134 return 0;
135 }
136
137
wps_process_cred_encr_type(struct wps_credential * cred,const u8 * encr_type)138 static int wps_process_cred_encr_type(struct wps_credential *cred,
139 const u8 *encr_type)
140 {
141 if (encr_type == NULL) {
142 wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
143 "Encryption Type");
144 return -1;
145 }
146
147 cred->encr_type = WPA_GET_BE16(encr_type);
148 wpa_printf(MSG_DEBUG, "WPS: Encryption Type: 0x%x",
149 cred->encr_type);
150
151 return 0;
152 }
153
154
wps_process_cred_network_key_idx(struct wps_credential * cred,const u8 * key_idx)155 static int wps_process_cred_network_key_idx(struct wps_credential *cred,
156 const u8 *key_idx)
157 {
158 if (key_idx == NULL)
159 return 0; /* optional attribute */
160
161 wpa_printf(MSG_DEBUG, "WPS: Network Key Index: %d", *key_idx);
162 cred->key_idx = *key_idx;
163
164 return 0;
165 }
166
167
wps_process_cred_network_key(struct wps_credential * cred,const u8 * key,size_t key_len)168 static int wps_process_cred_network_key(struct wps_credential *cred,
169 const u8 *key, size_t key_len)
170 {
171 if (key == NULL) {
172 wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
173 "Network Key");
174 if (cred->auth_type == WPS_AUTH_OPEN &&
175 cred->encr_type == WPS_ENCR_NONE) {
176 wpa_printf(MSG_DEBUG, "WPS: Workaround - Allow "
177 "missing mandatory Network Key attribute "
178 "for open network");
179 return 0;
180 }
181 return -1;
182 }
183
184 wpa_hexdump_key(MSG_DEBUG, "WPS: Network Key", key, key_len);
185 if (key_len <= sizeof(cred->key)) {
186 os_memcpy(cred->key, key, key_len);
187 cred->key_len = key_len;
188 }
189
190 return 0;
191 }
192
193
wps_process_cred_mac_addr(struct wps_credential * cred,const u8 * mac_addr)194 static int wps_process_cred_mac_addr(struct wps_credential *cred,
195 const u8 *mac_addr)
196 {
197 if (mac_addr == NULL) {
198 wpa_printf(MSG_DEBUG, "WPS: Credential did not include "
199 "MAC Address");
200 return -1;
201 }
202
203 wpa_printf(MSG_DEBUG, "WPS: MAC Address " MACSTR, MAC2STR(mac_addr));
204 os_memcpy(cred->mac_addr, mac_addr, ETH_ALEN);
205
206 return 0;
207 }
208
209
wps_workaround_cred_key(struct wps_credential * cred)210 static int wps_workaround_cred_key(struct wps_credential *cred)
211 {
212 if (cred->auth_type & (WPS_AUTH_WPAPSK | WPS_AUTH_WPA2PSK) &&
213 cred->key_len > 8 && cred->key_len < 64 &&
214 cred->key[cred->key_len - 1] == 0) {
215 #ifdef CONFIG_WPS_STRICT
216 wpa_printf(MSG_INFO, "WPS: WPA/WPA2-Personal passphrase uses "
217 "forbidden NULL termination");
218 wpa_hexdump_ascii_key(MSG_INFO, "WPS: Network Key",
219 cred->key, cred->key_len);
220 return -1;
221 #else /* CONFIG_WPS_STRICT */
222 /*
223 * A deployed external registrar is known to encode ASCII
224 * passphrases incorrectly. Remove the extra NULL termination
225 * to fix the encoding.
226 */
227 wpa_printf(MSG_DEBUG, "WPS: Workaround - remove NULL "
228 "termination from ASCII passphrase");
229 cred->key_len--;
230 #endif /* CONFIG_WPS_STRICT */
231 }
232 return 0;
233 }
234
235
wps_process_cred(struct wps_parse_attr * attr,struct wps_credential * cred)236 int wps_process_cred(struct wps_parse_attr *attr,
237 struct wps_credential *cred)
238 {
239 wpa_printf(MSG_DEBUG, "WPS: Process Credential");
240
241 /* TODO: support multiple Network Keys */
242 if (wps_process_cred_network_idx(cred, attr->network_idx) ||
243 wps_process_cred_ssid(cred, attr->ssid, attr->ssid_len) ||
244 wps_process_cred_auth_type(cred, attr->auth_type) ||
245 wps_process_cred_encr_type(cred, attr->encr_type) ||
246 wps_process_cred_network_key_idx(cred, attr->network_key_idx) ||
247 wps_process_cred_network_key(cred, attr->network_key,
248 attr->network_key_len) ||
249 wps_process_cred_mac_addr(cred, attr->mac_addr))
250 return -1;
251
252 return wps_workaround_cred_key(cred);
253 }
254
255
wps_process_ap_settings(struct wps_parse_attr * attr,struct wps_credential * cred)256 int wps_process_ap_settings(struct wps_parse_attr *attr,
257 struct wps_credential *cred)
258 {
259 wpa_printf(MSG_DEBUG, "WPS: Processing AP Settings");
260 os_memset(cred, 0, sizeof(*cred));
261 /* TODO: optional attributes New Password and Device Password ID */
262 if (wps_process_cred_ssid(cred, attr->ssid, attr->ssid_len) ||
263 wps_process_cred_auth_type(cred, attr->auth_type) ||
264 wps_process_cred_encr_type(cred, attr->encr_type) ||
265 wps_process_cred_network_key_idx(cred, attr->network_key_idx) ||
266 wps_process_cred_network_key(cred, attr->network_key,
267 attr->network_key_len) ||
268 wps_process_cred_mac_addr(cred, attr->mac_addr))
269 return -1;
270
271 return wps_workaround_cred_key(cred);
272 }
273