1 /*
2 * EAP server/peer: EAP-SAKE shared routines
3 * Copyright (c) 2006-2019, 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 "wpabuf.h"
13 #include "crypto/sha1.h"
14 #include "eap_defs.h"
15 #include "eap_sake_common.h"
16
17
eap_sake_parse_add_attr(struct eap_sake_parse_attr * attr,u8 attr_id,u8 len,const u8 * data)18 static int eap_sake_parse_add_attr(struct eap_sake_parse_attr *attr,
19 u8 attr_id, u8 len, const u8 *data)
20 {
21 size_t i;
22
23 switch (attr_id) {
24 case EAP_SAKE_AT_RAND_S:
25 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_S");
26 if (len != EAP_SAKE_RAND_LEN) {
27 wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_S with "
28 "invalid payload length %d", len);
29 return -1;
30 }
31 attr->rand_s = data;
32 break;
33 case EAP_SAKE_AT_RAND_P:
34 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_P");
35 if (len != EAP_SAKE_RAND_LEN) {
36 wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_P with "
37 "invalid payload length %d", len);
38 return -1;
39 }
40 attr->rand_p = data;
41 break;
42 case EAP_SAKE_AT_MIC_S:
43 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_S");
44 if (len != EAP_SAKE_MIC_LEN) {
45 wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_S with "
46 "invalid payload length %d", len);
47 return -1;
48 }
49 attr->mic_s = data;
50 break;
51 case EAP_SAKE_AT_MIC_P:
52 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_P");
53 if (len != EAP_SAKE_MIC_LEN) {
54 wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_P with "
55 "invalid payload length %d", len);
56 return -1;
57 }
58 attr->mic_p = data;
59 break;
60 case EAP_SAKE_AT_SERVERID:
61 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SERVERID");
62 attr->serverid = data;
63 attr->serverid_len = len;
64 break;
65 case EAP_SAKE_AT_PEERID:
66 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PEERID");
67 attr->peerid = data;
68 attr->peerid_len = len;
69 break;
70 case EAP_SAKE_AT_SPI_S:
71 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_S");
72 attr->spi_s = data;
73 attr->spi_s_len = len;
74 break;
75 case EAP_SAKE_AT_SPI_P:
76 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_P");
77 attr->spi_p = data;
78 attr->spi_p_len = len;
79 break;
80 case EAP_SAKE_AT_ANY_ID_REQ:
81 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ANY_ID_REQ");
82 if (len != 2) {
83 wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid AT_ANY_ID_REQ"
84 " payload length %d", len);
85 return -1;
86 }
87 attr->any_id_req = data;
88 break;
89 case EAP_SAKE_AT_PERM_ID_REQ:
90 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PERM_ID_REQ");
91 if (len != 2) {
92 wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
93 "AT_PERM_ID_REQ payload length %d", len);
94 return -1;
95 }
96 attr->perm_id_req = data;
97 break;
98 case EAP_SAKE_AT_ENCR_DATA:
99 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ENCR_DATA");
100 attr->encr_data = data;
101 attr->encr_data_len = len;
102 break;
103 case EAP_SAKE_AT_IV:
104 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV");
105 attr->iv = data;
106 attr->iv_len = len;
107 break;
108 case EAP_SAKE_AT_PADDING:
109 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PADDING");
110 for (i = 0; i < len; i++) {
111 if (data[i]) {
112 wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_PADDING "
113 "with non-zero pad byte");
114 return -1;
115 }
116 }
117 break;
118 case EAP_SAKE_AT_NEXT_TMPID:
119 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_NEXT_TMPID");
120 attr->next_tmpid = data;
121 attr->next_tmpid_len = len;
122 break;
123 case EAP_SAKE_AT_MSK_LIFE:
124 wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MSK_LIFE");
125 if (len != 4) {
126 wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
127 "AT_MSK_LIFE payload length %d", len);
128 return -1;
129 }
130 attr->msk_life = data;
131 break;
132 default:
133 if (attr_id < 128) {
134 wpa_printf(MSG_DEBUG, "EAP-SAKE: Unknown non-skippable"
135 " attribute %d", attr_id);
136 return -1;
137 }
138 wpa_printf(MSG_DEBUG, "EAP-SAKE: Ignoring unknown skippable "
139 "attribute %d", attr_id);
140 break;
141 }
142
143 if (attr->iv && !attr->encr_data) {
144 wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_IV included without "
145 "AT_ENCR_DATA");
146 return -1;
147 }
148
149 return 0;
150 }
151
152
153 /**
154 * eap_sake_parse_attributes - Parse EAP-SAKE attributes
155 * @buf: Packet payload (starting with the first attribute)
156 * @len: Payload length
157 * @attr: Structure to be filled with found attributes
158 * Returns: 0 on success or -1 on failure
159 */
eap_sake_parse_attributes(const u8 * buf,size_t len,struct eap_sake_parse_attr * attr)160 int eap_sake_parse_attributes(const u8 *buf, size_t len,
161 struct eap_sake_parse_attr *attr)
162 {
163 const u8 *pos = buf, *end = buf + len;
164
165 os_memset(attr, 0, sizeof(*attr));
166 while (pos < end) {
167 if (end - pos < 2) {
168 wpa_printf(MSG_DEBUG, "EAP-SAKE: Too short attribute");
169 return -1;
170 }
171
172 if (pos[1] < 2) {
173 wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid attribute "
174 "length (%d)", pos[1]);
175 return -1;
176 }
177
178 if (pos + pos[1] > end) {
179 wpa_printf(MSG_DEBUG, "EAP-SAKE: Attribute underflow");
180 return -1;
181 }
182
183 if (eap_sake_parse_add_attr(attr, pos[0], pos[1] - 2, pos + 2))
184 return -1;
185
186 pos += pos[1];
187 }
188
189 return 0;
190 }
191
192
193 /**
194 * eap_sake_kdf - EAP-SAKE Key Derivation Function (KDF)
195 * @key: Key for KDF
196 * @key_len: Length of the key in bytes
197 * @label: A unique label for each purpose of the KDF
198 * @data: Extra data (start) to bind into the key
199 * @data_len: Length of the data
200 * @data2: Extra data (end) to bind into the key
201 * @data2_len: Length of the data2
202 * @buf: Buffer for the generated pseudo-random key
203 * @buf_len: Number of bytes of key to generate
204 * Returns: 0 on success or -1 on failure
205 *
206 * This function is used to derive new, cryptographically separate keys from a
207 * given key (e.g., SMS). This is identical to the PRF used in IEEE 802.11i.
208 */
eap_sake_kdf(const u8 * key,size_t key_len,const char * label,const u8 * data,size_t data_len,const u8 * data2,size_t data2_len,u8 * buf,size_t buf_len)209 static int eap_sake_kdf(const u8 *key, size_t key_len, const char *label,
210 const u8 *data, size_t data_len,
211 const u8 *data2, size_t data2_len,
212 u8 *buf, size_t buf_len)
213 {
214 u8 counter = 0;
215 size_t pos, plen;
216 u8 hash[SHA1_MAC_LEN];
217 size_t label_len = os_strlen(label) + 1;
218 const unsigned char *addr[4];
219 size_t len[4];
220
221 addr[0] = (u8 *) label; /* Label | Y */
222 len[0] = label_len;
223 addr[1] = data; /* Msg[start] */
224 len[1] = data_len;
225 addr[2] = data2; /* Msg[end] */
226 len[2] = data2_len;
227 addr[3] = &counter; /* Length */
228 len[3] = 1;
229
230 pos = 0;
231 while (pos < buf_len) {
232 plen = buf_len - pos;
233 if (plen >= SHA1_MAC_LEN) {
234 if (hmac_sha1_vector(key, key_len, 4, addr, len,
235 &buf[pos]) < 0)
236 return -1;
237 pos += SHA1_MAC_LEN;
238 } else {
239 if (hmac_sha1_vector(key, key_len, 4, addr, len,
240 hash) < 0)
241 return -1;
242 os_memcpy(&buf[pos], hash, plen);
243 break;
244 }
245 counter++;
246 }
247
248 return 0;
249 }
250
251
252 /**
253 * eap_sake_derive_keys - Derive EAP-SAKE keys
254 * @root_secret_a: 16-byte Root-Secret-A
255 * @root_secret_b: 16-byte Root-Secret-B
256 * @rand_s: 16-byte RAND_S
257 * @rand_p: 16-byte RAND_P
258 * @tek: Buffer for Temporary EAK Keys (TEK-Auth[16] | TEK-Cipher[16])
259 * @msk: Buffer for 64-byte MSK
260 * @emsk: Buffer for 64-byte EMSK
261 * Returns: 0 on success or -1 on failure
262 *
263 * This function derives EAP-SAKE keys as defined in RFC 4763, section 3.2.6.
264 */
eap_sake_derive_keys(const u8 * root_secret_a,const u8 * root_secret_b,const u8 * rand_s,const u8 * rand_p,u8 * tek,u8 * msk,u8 * emsk)265 int eap_sake_derive_keys(const u8 *root_secret_a, const u8 *root_secret_b,
266 const u8 *rand_s, const u8 *rand_p, u8 *tek, u8 *msk,
267 u8 *emsk)
268 {
269 u8 sms_a[EAP_SAKE_SMS_LEN];
270 u8 sms_b[EAP_SAKE_SMS_LEN];
271 u8 key_buf[EAP_MSK_LEN + EAP_EMSK_LEN];
272
273 wpa_printf(MSG_DEBUG, "EAP-SAKE: Deriving keys");
274
275 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-A",
276 root_secret_a, EAP_SAKE_ROOT_SECRET_LEN);
277 if (eap_sake_kdf(root_secret_a, EAP_SAKE_ROOT_SECRET_LEN,
278 "SAKE Master Secret A",
279 rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
280 sms_a, EAP_SAKE_SMS_LEN) < 0)
281 return -1;
282 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-A", sms_a, EAP_SAKE_SMS_LEN);
283 if (eap_sake_kdf(sms_a, EAP_SAKE_SMS_LEN, "Transient EAP Key",
284 rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
285 tek, EAP_SAKE_TEK_LEN) < 0)
286 return -1;
287 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Auth",
288 tek, EAP_SAKE_TEK_AUTH_LEN);
289 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Cipher",
290 tek + EAP_SAKE_TEK_AUTH_LEN, EAP_SAKE_TEK_CIPHER_LEN);
291
292 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-B",
293 root_secret_b, EAP_SAKE_ROOT_SECRET_LEN);
294 if (eap_sake_kdf(root_secret_b, EAP_SAKE_ROOT_SECRET_LEN,
295 "SAKE Master Secret B",
296 rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
297 sms_b, EAP_SAKE_SMS_LEN) < 0)
298 return -1;
299 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-B", sms_b, EAP_SAKE_SMS_LEN);
300 if (eap_sake_kdf(sms_b, EAP_SAKE_SMS_LEN, "Master Session Key",
301 rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
302 key_buf, sizeof(key_buf)) < 0)
303 return -1;
304 os_memcpy(msk, key_buf, EAP_MSK_LEN);
305 os_memcpy(emsk, key_buf + EAP_MSK_LEN, EAP_EMSK_LEN);
306 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: MSK", msk, EAP_MSK_LEN);
307 wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: EMSK", emsk, EAP_EMSK_LEN);
308 return 0;
309 }
310
311
312 /**
313 * eap_sake_compute_mic - Compute EAP-SAKE MIC for an EAP packet
314 * @tek_auth: 16-byte TEK-Auth
315 * @rand_s: 16-byte RAND_S
316 * @rand_p: 16-byte RAND_P
317 * @serverid: SERVERID
318 * @serverid_len: SERVERID length
319 * @peerid: PEERID
320 * @peerid_len: PEERID length
321 * @peer: MIC calculation for 0 = Server, 1 = Peer message
322 * @eap: EAP packet
323 * @eap_len: EAP packet length
324 * @mic_pos: MIC position in the EAP packet (must be [eap .. eap + eap_len])
325 * @mic: Buffer for the computed 16-byte MIC
326 * Returns: 0 on success or -1 on failure
327 */
eap_sake_compute_mic(const u8 * tek_auth,const u8 * rand_s,const u8 * rand_p,const u8 * serverid,size_t serverid_len,const u8 * peerid,size_t peerid_len,int peer,const u8 * eap,size_t eap_len,const u8 * mic_pos,u8 * mic)328 int eap_sake_compute_mic(const u8 *tek_auth,
329 const u8 *rand_s, const u8 *rand_p,
330 const u8 *serverid, size_t serverid_len,
331 const u8 *peerid, size_t peerid_len,
332 int peer, const u8 *eap, size_t eap_len,
333 const u8 *mic_pos, u8 *mic)
334 {
335 u8 _rand[2 * EAP_SAKE_RAND_LEN];
336 u8 *tmp, *pos;
337 size_t tmplen;
338 int ret;
339
340 tmplen = serverid_len + 1 + peerid_len + 1 + eap_len;
341 tmp = os_malloc(tmplen);
342 if (tmp == NULL)
343 return -1;
344 pos = tmp;
345 if (peer) {
346 if (peerid) {
347 os_memcpy(pos, peerid, peerid_len);
348 pos += peerid_len;
349 }
350 *pos++ = 0x00;
351 if (serverid) {
352 os_memcpy(pos, serverid, serverid_len);
353 pos += serverid_len;
354 }
355 *pos++ = 0x00;
356
357 os_memcpy(_rand, rand_s, EAP_SAKE_RAND_LEN);
358 os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_p,
359 EAP_SAKE_RAND_LEN);
360 } else {
361 if (serverid) {
362 os_memcpy(pos, serverid, serverid_len);
363 pos += serverid_len;
364 }
365 *pos++ = 0x00;
366 if (peerid) {
367 os_memcpy(pos, peerid, peerid_len);
368 pos += peerid_len;
369 }
370 *pos++ = 0x00;
371
372 os_memcpy(_rand, rand_p, EAP_SAKE_RAND_LEN);
373 os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_s,
374 EAP_SAKE_RAND_LEN);
375 }
376
377 os_memcpy(pos, eap, eap_len);
378 os_memset(pos + (mic_pos - eap), 0, EAP_SAKE_MIC_LEN);
379
380 ret = eap_sake_kdf(tek_auth, EAP_SAKE_TEK_AUTH_LEN,
381 peer ? "Peer MIC" : "Server MIC",
382 _rand, 2 * EAP_SAKE_RAND_LEN, tmp, tmplen,
383 mic, EAP_SAKE_MIC_LEN);
384
385 os_free(tmp);
386
387 return ret;
388 }
389
390
eap_sake_add_attr(struct wpabuf * buf,u8 type,const u8 * data,size_t len)391 void eap_sake_add_attr(struct wpabuf *buf, u8 type, const u8 *data,
392 size_t len)
393 {
394 wpabuf_put_u8(buf, type);
395 wpabuf_put_u8(buf, 2 + len); /* Length; including attr header */
396 if (data)
397 wpabuf_put_data(buf, data, len);
398 else
399 os_memset(wpabuf_put(buf, len), 0, len);
400 }
401