Line data Source code
1 : /*
2 : * EAP server/peer: EAP-SAKE shared routines
3 : * Copyright (c) 2006-2007, 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 :
18 19 : static int eap_sake_parse_add_attr(struct eap_sake_parse_attr *attr,
19 : const u8 *pos)
20 : {
21 : size_t i;
22 :
23 19 : switch (pos[0]) {
24 : case EAP_SAKE_AT_RAND_S:
25 3 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_S");
26 3 : if (pos[1] != 2 + EAP_SAKE_RAND_LEN) {
27 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_S with "
28 0 : "invalid length %d", pos[1]);
29 0 : return -1;
30 : }
31 3 : attr->rand_s = pos + 2;
32 3 : break;
33 : case EAP_SAKE_AT_RAND_P:
34 3 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_P");
35 3 : if (pos[1] != 2 + EAP_SAKE_RAND_LEN) {
36 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_P with "
37 0 : "invalid length %d", pos[1]);
38 0 : return -1;
39 : }
40 3 : attr->rand_p = pos + 2;
41 3 : break;
42 : case EAP_SAKE_AT_MIC_S:
43 2 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_S");
44 2 : if (pos[1] != 2 + EAP_SAKE_MIC_LEN) {
45 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_S with "
46 0 : "invalid length %d", pos[1]);
47 0 : return -1;
48 : }
49 2 : attr->mic_s = pos + 2;
50 2 : break;
51 : case EAP_SAKE_AT_MIC_P:
52 5 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_P");
53 5 : if (pos[1] != 2 + EAP_SAKE_MIC_LEN) {
54 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_P with "
55 0 : "invalid length %d", pos[1]);
56 0 : return -1;
57 : }
58 5 : attr->mic_p = pos + 2;
59 5 : break;
60 : case EAP_SAKE_AT_SERVERID:
61 3 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SERVERID");
62 3 : attr->serverid = pos + 2;
63 3 : attr->serverid_len = pos[1] - 2;
64 3 : break;
65 : case EAP_SAKE_AT_PEERID:
66 3 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PEERID");
67 3 : attr->peerid = pos + 2;
68 3 : attr->peerid_len = pos[1] - 2;
69 3 : break;
70 : case EAP_SAKE_AT_SPI_S:
71 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_S");
72 0 : attr->spi_s = pos + 2;
73 0 : attr->spi_s_len = pos[1] - 2;
74 0 : break;
75 : case EAP_SAKE_AT_SPI_P:
76 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_P");
77 0 : attr->spi_p = pos + 2;
78 0 : attr->spi_p_len = pos[1] - 2;
79 0 : break;
80 : case EAP_SAKE_AT_ANY_ID_REQ:
81 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ANY_ID_REQ");
82 0 : if (pos[1] != 4) {
83 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid AT_ANY_ID_REQ"
84 0 : " length %d", pos[1]);
85 0 : return -1;
86 : }
87 0 : attr->any_id_req = pos + 2;
88 0 : break;
89 : case EAP_SAKE_AT_PERM_ID_REQ:
90 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PERM_ID_REQ");
91 0 : if (pos[1] != 4) {
92 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
93 0 : "AT_PERM_ID_REQ length %d", pos[1]);
94 0 : return -1;
95 : }
96 0 : attr->perm_id_req = pos + 2;
97 0 : break;
98 : case EAP_SAKE_AT_ENCR_DATA:
99 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ENCR_DATA");
100 0 : attr->encr_data = pos + 2;
101 0 : attr->encr_data_len = pos[1] - 2;
102 0 : break;
103 : case EAP_SAKE_AT_IV:
104 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV");
105 0 : attr->iv = pos + 2;
106 0 : attr->iv_len = pos[1] - 2;
107 0 : break;
108 : case EAP_SAKE_AT_PADDING:
109 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PADDING");
110 0 : for (i = 2; i < pos[1]; i++) {
111 0 : if (pos[i]) {
112 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_PADDING "
113 : "with non-zero pad byte");
114 0 : return -1;
115 : }
116 : }
117 0 : break;
118 : case EAP_SAKE_AT_NEXT_TMPID:
119 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_NEXT_TMPID");
120 0 : attr->next_tmpid = pos + 2;
121 0 : attr->next_tmpid_len = pos[1] - 2;
122 0 : break;
123 : case EAP_SAKE_AT_MSK_LIFE:
124 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV");
125 0 : if (pos[1] != 6) {
126 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid "
127 0 : "AT_MSK_LIFE length %d", pos[1]);
128 0 : return -1;
129 : }
130 0 : attr->msk_life = pos + 2;
131 0 : break;
132 : default:
133 0 : if (pos[0] < 128) {
134 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Unknown non-skippable"
135 0 : " attribute %d", pos[0]);
136 0 : return -1;
137 : }
138 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Ignoring unknown skippable "
139 0 : "attribute %d", pos[0]);
140 0 : break;
141 : }
142 :
143 19 : if (attr->iv && !attr->encr_data) {
144 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_IV included without "
145 : "AT_ENCR_DATA");
146 0 : return -1;
147 : }
148 :
149 19 : 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 : */
160 10 : int eap_sake_parse_attributes(const u8 *buf, size_t len,
161 : struct eap_sake_parse_attr *attr)
162 : {
163 10 : const u8 *pos = buf, *end = buf + len;
164 :
165 10 : os_memset(attr, 0, sizeof(*attr));
166 39 : while (pos < end) {
167 19 : if (end - pos < 2) {
168 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Too short attribute");
169 0 : return -1;
170 : }
171 :
172 19 : if (pos[1] < 2) {
173 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid attribute "
174 0 : "length (%d)", pos[1]);
175 0 : return -1;
176 : }
177 :
178 19 : if (pos + pos[1] > end) {
179 0 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Attribute underflow");
180 0 : return -1;
181 : }
182 :
183 19 : if (eap_sake_parse_add_attr(attr, pos))
184 0 : return -1;
185 :
186 19 : pos += pos[1];
187 : }
188 :
189 10 : 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 : *
205 : * This function is used to derive new, cryptographically separate keys from a
206 : * given key (e.g., SMS). This is identical to the PRF used in IEEE 802.11i.
207 : */
208 38 : static void eap_sake_kdf(const u8 *key, size_t key_len, const char *label,
209 : const u8 *data, size_t data_len,
210 : const u8 *data2, size_t data2_len,
211 : u8 *buf, size_t buf_len)
212 : {
213 38 : u8 counter = 0;
214 : size_t pos, plen;
215 : u8 hash[SHA1_MAC_LEN];
216 38 : size_t label_len = os_strlen(label) + 1;
217 : const unsigned char *addr[4];
218 : size_t len[4];
219 :
220 38 : addr[0] = (u8 *) label; /* Label | Y */
221 38 : len[0] = label_len;
222 38 : addr[1] = data; /* Msg[start] */
223 38 : len[1] = data_len;
224 38 : addr[2] = data2; /* Msg[end] */
225 38 : len[2] = data2_len;
226 38 : addr[3] = &counter; /* Length */
227 38 : len[3] = 1;
228 :
229 38 : pos = 0;
230 118 : while (pos < buf_len) {
231 80 : plen = buf_len - pos;
232 80 : if (plen >= SHA1_MAC_LEN) {
233 42 : hmac_sha1_vector(key, key_len, 4, addr, len,
234 : &buf[pos]);
235 42 : pos += SHA1_MAC_LEN;
236 : } else {
237 38 : hmac_sha1_vector(key, key_len, 4, addr, len,
238 : hash);
239 38 : os_memcpy(&buf[pos], hash, plen);
240 38 : break;
241 : }
242 42 : counter++;
243 : }
244 38 : }
245 :
246 :
247 : /**
248 : * eap_sake_derive_keys - Derive EAP-SAKE keys
249 : * @root_secret_a: 16-byte Root-Secret-A
250 : * @root_secret_b: 16-byte Root-Secret-B
251 : * @rand_s: 16-byte RAND_S
252 : * @rand_p: 16-byte RAND_P
253 : * @tek: Buffer for Temporary EAK Keys (TEK-Auth[16] | TEK-Cipher[16])
254 : * @msk: Buffer for 64-byte MSK
255 : * @emsk: Buffer for 64-byte EMSK
256 : *
257 : * This function derives EAP-SAKE keys as defined in RFC 4763, section 3.2.6.
258 : */
259 6 : void eap_sake_derive_keys(const u8 *root_secret_a, const u8 *root_secret_b,
260 : const u8 *rand_s, const u8 *rand_p, u8 *tek, u8 *msk,
261 : u8 *emsk)
262 : {
263 : u8 sms_a[EAP_SAKE_SMS_LEN];
264 : u8 sms_b[EAP_SAKE_SMS_LEN];
265 : u8 key_buf[EAP_MSK_LEN + EAP_EMSK_LEN];
266 :
267 6 : wpa_printf(MSG_DEBUG, "EAP-SAKE: Deriving keys");
268 :
269 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-A",
270 : root_secret_a, EAP_SAKE_ROOT_SECRET_LEN);
271 6 : eap_sake_kdf(root_secret_a, EAP_SAKE_ROOT_SECRET_LEN,
272 : "SAKE Master Secret A",
273 : rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
274 : sms_a, EAP_SAKE_SMS_LEN);
275 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-A", sms_a, EAP_SAKE_SMS_LEN);
276 6 : eap_sake_kdf(sms_a, EAP_SAKE_SMS_LEN, "Transient EAP Key",
277 : rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
278 : tek, EAP_SAKE_TEK_LEN);
279 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Auth",
280 : tek, EAP_SAKE_TEK_AUTH_LEN);
281 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Cipher",
282 : tek + EAP_SAKE_TEK_AUTH_LEN, EAP_SAKE_TEK_CIPHER_LEN);
283 :
284 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-B",
285 : root_secret_b, EAP_SAKE_ROOT_SECRET_LEN);
286 6 : eap_sake_kdf(root_secret_b, EAP_SAKE_ROOT_SECRET_LEN,
287 : "SAKE Master Secret B",
288 : rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN,
289 : sms_b, EAP_SAKE_SMS_LEN);
290 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-B", sms_b, EAP_SAKE_SMS_LEN);
291 6 : eap_sake_kdf(sms_b, EAP_SAKE_SMS_LEN, "Master Session Key",
292 : rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN,
293 : key_buf, sizeof(key_buf));
294 6 : os_memcpy(msk, key_buf, EAP_MSK_LEN);
295 6 : os_memcpy(emsk, key_buf + EAP_MSK_LEN, EAP_EMSK_LEN);
296 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: MSK", msk, EAP_MSK_LEN);
297 6 : wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: EMSK", emsk, EAP_EMSK_LEN);
298 6 : }
299 :
300 :
301 : /**
302 : * eap_sake_compute_mic - Compute EAP-SAKE MIC for an EAP packet
303 : * @tek_auth: 16-byte TEK-Auth
304 : * @rand_s: 16-byte RAND_S
305 : * @rand_p: 16-byte RAND_P
306 : * @serverid: SERVERID
307 : * @serverid_len: SERVERID length
308 : * @peerid: PEERID
309 : * @peerid_len: PEERID length
310 : * @peer: MIC calculation for 0 = Server, 1 = Peer message
311 : * @eap: EAP packet
312 : * @eap_len: EAP packet length
313 : * @mic_pos: MIC position in the EAP packet (must be [eap .. eap + eap_len])
314 : * @mic: Buffer for the computed 16-byte MIC
315 : */
316 14 : int eap_sake_compute_mic(const u8 *tek_auth,
317 : const u8 *rand_s, const u8 *rand_p,
318 : const u8 *serverid, size_t serverid_len,
319 : const u8 *peerid, size_t peerid_len,
320 : int peer, const u8 *eap, size_t eap_len,
321 : const u8 *mic_pos, u8 *mic)
322 : {
323 : u8 _rand[2 * EAP_SAKE_RAND_LEN];
324 : u8 *tmp, *pos;
325 : size_t tmplen;
326 :
327 14 : tmplen = serverid_len + 1 + peerid_len + 1 + eap_len;
328 14 : tmp = os_malloc(tmplen);
329 14 : if (tmp == NULL)
330 0 : return -1;
331 14 : pos = tmp;
332 14 : if (peer) {
333 10 : if (peerid) {
334 10 : os_memcpy(pos, peerid, peerid_len);
335 10 : pos += peerid_len;
336 : }
337 10 : *pos++ = 0x00;
338 10 : if (serverid) {
339 10 : os_memcpy(pos, serverid, serverid_len);
340 10 : pos += serverid_len;
341 : }
342 10 : *pos++ = 0x00;
343 :
344 10 : os_memcpy(_rand, rand_s, EAP_SAKE_RAND_LEN);
345 10 : os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_p,
346 : EAP_SAKE_RAND_LEN);
347 : } else {
348 4 : if (serverid) {
349 4 : os_memcpy(pos, serverid, serverid_len);
350 4 : pos += serverid_len;
351 : }
352 4 : *pos++ = 0x00;
353 4 : if (peerid) {
354 4 : os_memcpy(pos, peerid, peerid_len);
355 4 : pos += peerid_len;
356 : }
357 4 : *pos++ = 0x00;
358 :
359 4 : os_memcpy(_rand, rand_p, EAP_SAKE_RAND_LEN);
360 4 : os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_s,
361 : EAP_SAKE_RAND_LEN);
362 : }
363 :
364 14 : os_memcpy(pos, eap, eap_len);
365 14 : os_memset(pos + (mic_pos - eap), 0, EAP_SAKE_MIC_LEN);
366 :
367 14 : eap_sake_kdf(tek_auth, EAP_SAKE_TEK_AUTH_LEN,
368 : peer ? "Peer MIC" : "Server MIC",
369 : _rand, 2 * EAP_SAKE_RAND_LEN, tmp, tmplen,
370 : mic, EAP_SAKE_MIC_LEN);
371 :
372 14 : os_free(tmp);
373 :
374 14 : return 0;
375 : }
376 :
377 :
378 12 : void eap_sake_add_attr(struct wpabuf *buf, u8 type, const u8 *data,
379 : size_t len)
380 : {
381 12 : wpabuf_put_u8(buf, type);
382 12 : wpabuf_put_u8(buf, 2 + len); /* Length; including attr header */
383 12 : if (data)
384 12 : wpabuf_put_data(buf, data, len);
385 : else
386 0 : os_memset(wpabuf_put(buf, len), 0, len);
387 12 : }
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