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 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 */ 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 */ 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 */ 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 */ 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 } 389 390 391 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