The Android Open Source Project | 845e012 | 2009-03-03 19:31:34 -0800 | [diff] [blame] | 1 | /* |
| 2 | * EAP server/peer: EAP-SAKE shared routines |
| 3 | * Copyright (c) 2006, 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 "sha1.h" |
| 19 | #include "eap_defs.h" |
| 20 | #include "eap_sake_common.h" |
| 21 | |
| 22 | |
| 23 | static int eap_sake_parse_add_attr(struct eap_sake_parse_attr *attr, |
| 24 | const u8 *pos) |
| 25 | { |
| 26 | size_t i; |
| 27 | |
| 28 | switch (pos[0]) { |
| 29 | case EAP_SAKE_AT_RAND_S: |
| 30 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_S"); |
| 31 | if (pos[1] != 2 + EAP_SAKE_RAND_LEN) { |
| 32 | wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_S with " |
| 33 | "invalid length %d", pos[1]); |
| 34 | return -1; |
| 35 | } |
| 36 | attr->rand_s = pos + 2; |
| 37 | break; |
| 38 | case EAP_SAKE_AT_RAND_P: |
| 39 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_RAND_P"); |
| 40 | if (pos[1] != 2 + EAP_SAKE_RAND_LEN) { |
| 41 | wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_RAND_P with " |
| 42 | "invalid length %d", pos[1]); |
| 43 | return -1; |
| 44 | } |
| 45 | attr->rand_p = pos + 2; |
| 46 | break; |
| 47 | case EAP_SAKE_AT_MIC_S: |
| 48 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_S"); |
| 49 | if (pos[1] != 2 + EAP_SAKE_MIC_LEN) { |
| 50 | wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_S with " |
| 51 | "invalid length %d", pos[1]); |
| 52 | return -1; |
| 53 | } |
| 54 | attr->mic_s = pos + 2; |
| 55 | break; |
| 56 | case EAP_SAKE_AT_MIC_P: |
| 57 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_MIC_P"); |
| 58 | if (pos[1] != 2 + EAP_SAKE_MIC_LEN) { |
| 59 | wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_MIC_P with " |
| 60 | "invalid length %d", pos[1]); |
| 61 | return -1; |
| 62 | } |
| 63 | attr->mic_p = pos + 2; |
| 64 | break; |
| 65 | case EAP_SAKE_AT_SERVERID: |
| 66 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SERVERID"); |
| 67 | attr->serverid = pos + 2; |
| 68 | attr->serverid_len = pos[1] - 2; |
| 69 | break; |
| 70 | case EAP_SAKE_AT_PEERID: |
| 71 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PEERID"); |
| 72 | attr->peerid = pos + 2; |
| 73 | attr->peerid_len = pos[1] - 2; |
| 74 | break; |
| 75 | case EAP_SAKE_AT_SPI_S: |
| 76 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_S"); |
| 77 | attr->spi_s = pos + 2; |
| 78 | attr->spi_s_len = pos[1] - 2; |
| 79 | break; |
| 80 | case EAP_SAKE_AT_SPI_P: |
| 81 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_SPI_P"); |
| 82 | attr->spi_p = pos + 2; |
| 83 | attr->spi_p_len = pos[1] - 2; |
| 84 | break; |
| 85 | case EAP_SAKE_AT_ANY_ID_REQ: |
| 86 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ANY_ID_REQ"); |
| 87 | if (pos[1] != 4) { |
| 88 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid AT_ANY_ID_REQ" |
| 89 | " length %d", pos[1]); |
| 90 | return -1; |
| 91 | } |
| 92 | attr->any_id_req = pos + 2; |
| 93 | break; |
| 94 | case EAP_SAKE_AT_PERM_ID_REQ: |
| 95 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PERM_ID_REQ"); |
| 96 | if (pos[1] != 4) { |
| 97 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid " |
| 98 | "AT_PERM_ID_REQ length %d", pos[1]); |
| 99 | return -1; |
| 100 | } |
| 101 | attr->perm_id_req = pos + 2; |
| 102 | break; |
| 103 | case EAP_SAKE_AT_ENCR_DATA: |
| 104 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_ENCR_DATA"); |
| 105 | attr->encr_data = pos + 2; |
| 106 | attr->encr_data_len = pos[1] - 2; |
| 107 | break; |
| 108 | case EAP_SAKE_AT_IV: |
| 109 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV"); |
| 110 | attr->iv = pos + 2; |
| 111 | attr->iv_len = pos[1] - 2; |
| 112 | break; |
| 113 | case EAP_SAKE_AT_PADDING: |
| 114 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_PADDING"); |
| 115 | for (i = 2; i < pos[1]; i++) { |
| 116 | if (pos[i]) { |
| 117 | wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_PADDING " |
| 118 | "with non-zero pad byte"); |
| 119 | return -1; |
| 120 | } |
| 121 | } |
| 122 | break; |
| 123 | case EAP_SAKE_AT_NEXT_TMPID: |
| 124 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_NEXT_TMPID"); |
| 125 | attr->next_tmpid = pos + 2; |
| 126 | attr->next_tmpid_len = pos[1] - 2; |
| 127 | break; |
| 128 | case EAP_SAKE_AT_MSK_LIFE: |
| 129 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Parse: AT_IV"); |
| 130 | if (pos[1] != 6) { |
| 131 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid " |
| 132 | "AT_MSK_LIFE length %d", pos[1]); |
| 133 | return -1; |
| 134 | } |
| 135 | attr->msk_life = pos + 2; |
| 136 | break; |
| 137 | default: |
| 138 | if (pos[0] < 128) { |
| 139 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Unknown non-skippable" |
| 140 | " attribute %d", pos[0]); |
| 141 | return -1; |
| 142 | } |
| 143 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Ignoring unknown skippable " |
| 144 | "attribute %d", pos[0]); |
| 145 | break; |
| 146 | } |
| 147 | |
| 148 | if (attr->iv && !attr->encr_data) { |
| 149 | wpa_printf(MSG_DEBUG, "EAP-SAKE: AT_IV included without " |
| 150 | "AT_ENCR_DATA"); |
| 151 | return -1; |
| 152 | } |
| 153 | |
| 154 | return 0; |
| 155 | } |
| 156 | |
| 157 | |
| 158 | /** |
| 159 | * eap_sake_parse_attributes - Parse EAP-SAKE attributes |
| 160 | * @buf: Packet payload (starting with the first attribute) |
| 161 | * @len: Payload length |
| 162 | * @attr: Structure to be filled with found attributes |
| 163 | * Returns: 0 on success or -1 on failure |
| 164 | */ |
| 165 | int eap_sake_parse_attributes(const u8 *buf, size_t len, |
| 166 | struct eap_sake_parse_attr *attr) |
| 167 | { |
| 168 | const u8 *pos = buf, *end = buf + len; |
| 169 | |
| 170 | os_memset(attr, 0, sizeof(*attr)); |
| 171 | while (pos < end) { |
| 172 | if (end - pos < 2) { |
| 173 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Too short attribute"); |
| 174 | return -1; |
| 175 | } |
| 176 | |
| 177 | if (pos[1] < 2) { |
| 178 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Invalid attribute " |
| 179 | "length (%d)", pos[1]); |
| 180 | return -1; |
| 181 | } |
| 182 | |
| 183 | if (pos + pos[1] > end) { |
| 184 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Attribute underflow"); |
| 185 | return -1; |
| 186 | } |
| 187 | |
| 188 | if (eap_sake_parse_add_attr(attr, pos)) |
| 189 | return -1; |
| 190 | |
| 191 | pos += pos[1]; |
| 192 | } |
| 193 | |
| 194 | return 0; |
| 195 | } |
| 196 | |
| 197 | |
| 198 | /** |
| 199 | * eap_sake_kdf - EAP-SAKE Key Derivation Function (KDF) |
| 200 | * @key: Key for KDF |
| 201 | * @key_len: Length of the key in bytes |
| 202 | * @label: A unique label for each purpose of the KDF |
| 203 | * @data: Extra data (start) to bind into the key |
| 204 | * @data_len: Length of the data |
| 205 | * @data2: Extra data (end) to bind into the key |
| 206 | * @data2_len: Length of the data2 |
| 207 | * @buf: Buffer for the generated pseudo-random key |
| 208 | * @buf_len: Number of bytes of key to generate |
| 209 | * |
| 210 | * This function is used to derive new, cryptographically separate keys from a |
| 211 | * given key (e.g., SMS). This is identical to the PRF used in IEEE 802.11i. |
| 212 | */ |
| 213 | static void eap_sake_kdf(const u8 *key, size_t key_len, const char *label, |
| 214 | const u8 *data, size_t data_len, |
| 215 | const u8 *data2, size_t data2_len, |
| 216 | u8 *buf, size_t buf_len) |
| 217 | { |
| 218 | u8 counter = 0; |
| 219 | size_t pos, plen; |
| 220 | u8 hash[SHA1_MAC_LEN]; |
| 221 | size_t label_len = os_strlen(label) + 1; |
| 222 | const unsigned char *addr[4]; |
| 223 | size_t len[4]; |
| 224 | |
| 225 | addr[0] = (u8 *) label; /* Label | Y */ |
| 226 | len[0] = label_len; |
| 227 | addr[1] = data; /* Msg[start] */ |
| 228 | len[1] = data_len; |
| 229 | addr[2] = data2; /* Msg[end] */ |
| 230 | len[2] = data2_len; |
| 231 | addr[3] = &counter; /* Length */ |
| 232 | len[3] = 1; |
| 233 | |
| 234 | pos = 0; |
| 235 | while (pos < buf_len) { |
| 236 | plen = buf_len - pos; |
| 237 | if (plen >= SHA1_MAC_LEN) { |
| 238 | hmac_sha1_vector(key, key_len, 4, addr, len, |
| 239 | &buf[pos]); |
| 240 | pos += SHA1_MAC_LEN; |
| 241 | } else { |
| 242 | hmac_sha1_vector(key, key_len, 4, addr, len, |
| 243 | hash); |
| 244 | os_memcpy(&buf[pos], hash, plen); |
| 245 | break; |
| 246 | } |
| 247 | counter++; |
| 248 | } |
| 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 | * |
| 262 | * This function derives EAP-SAKE keys as defined in RFC 4763, section 3.2.6. |
| 263 | */ |
| 264 | void eap_sake_derive_keys(const u8 *root_secret_a, const u8 *root_secret_b, |
| 265 | const u8 *rand_s, const u8 *rand_p, u8 *tek, u8 *msk, |
| 266 | u8 *emsk) |
| 267 | { |
| 268 | u8 sms_a[EAP_SAKE_SMS_LEN]; |
| 269 | u8 sms_b[EAP_SAKE_SMS_LEN]; |
| 270 | u8 key_buf[EAP_MSK_LEN + EAP_EMSK_LEN]; |
| 271 | |
| 272 | wpa_printf(MSG_DEBUG, "EAP-SAKE: Deriving keys"); |
| 273 | |
| 274 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-A", |
| 275 | root_secret_a, EAP_SAKE_ROOT_SECRET_LEN); |
| 276 | eap_sake_kdf(root_secret_a, EAP_SAKE_ROOT_SECRET_LEN, |
| 277 | "SAKE Master Secret A", |
| 278 | rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN, |
| 279 | sms_a, EAP_SAKE_SMS_LEN); |
| 280 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-A", sms_a, EAP_SAKE_SMS_LEN); |
| 281 | eap_sake_kdf(sms_a, EAP_SAKE_SMS_LEN, "Transient EAP Key", |
| 282 | rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN, |
| 283 | tek, EAP_SAKE_TEK_LEN); |
| 284 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Auth", |
| 285 | tek, EAP_SAKE_TEK_AUTH_LEN); |
| 286 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: TEK-Cipher", |
| 287 | tek + EAP_SAKE_TEK_AUTH_LEN, EAP_SAKE_TEK_CIPHER_LEN); |
| 288 | |
| 289 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: Root-Secret-B", |
| 290 | root_secret_b, EAP_SAKE_ROOT_SECRET_LEN); |
| 291 | eap_sake_kdf(root_secret_b, EAP_SAKE_ROOT_SECRET_LEN, |
| 292 | "SAKE Master Secret B", |
| 293 | rand_p, EAP_SAKE_RAND_LEN, rand_s, EAP_SAKE_RAND_LEN, |
| 294 | sms_b, EAP_SAKE_SMS_LEN); |
| 295 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: SMS-B", sms_b, EAP_SAKE_SMS_LEN); |
| 296 | eap_sake_kdf(sms_b, EAP_SAKE_SMS_LEN, "Master Session Key", |
| 297 | rand_s, EAP_SAKE_RAND_LEN, rand_p, EAP_SAKE_RAND_LEN, |
| 298 | key_buf, sizeof(key_buf)); |
| 299 | os_memcpy(msk, key_buf, EAP_MSK_LEN); |
| 300 | os_memcpy(emsk, key_buf + EAP_MSK_LEN, EAP_EMSK_LEN); |
| 301 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: MSK", msk, EAP_MSK_LEN); |
| 302 | wpa_hexdump_key(MSG_DEBUG, "EAP-SAKE: EMSK", emsk, EAP_EMSK_LEN); |
| 303 | } |
| 304 | |
| 305 | |
| 306 | /** |
| 307 | * eap_sake_compute_mic - Compute EAP-SAKE MIC for an EAP packet |
| 308 | * @tek_auth: 16-byte TEK-Auth |
| 309 | * @rand_s: 16-byte RAND_S |
| 310 | * @rand_p: 16-byte RAND_P |
| 311 | * @serverid: SERVERID |
| 312 | * @serverid_len: SERVERID length |
| 313 | * @peerid: PEERID |
| 314 | * @peerid_len: PEERID length |
| 315 | * @peer: MIC calculation for 0 = Server, 1 = Peer message |
| 316 | * @eap: EAP packet |
| 317 | * @eap_len: EAP packet length |
| 318 | * @mic_pos: MIC position in the EAP packet (must be [eap .. eap + eap_len]) |
| 319 | * @mic: Buffer for the computed 16-byte MIC |
| 320 | */ |
| 321 | int eap_sake_compute_mic(const u8 *tek_auth, |
| 322 | const u8 *rand_s, const u8 *rand_p, |
| 323 | const u8 *serverid, size_t serverid_len, |
| 324 | const u8 *peerid, size_t peerid_len, |
| 325 | int peer, const u8 *eap, size_t eap_len, |
| 326 | const u8 *mic_pos, u8 *mic) |
| 327 | { |
| 328 | u8 _rand[2 * EAP_SAKE_RAND_LEN]; |
| 329 | u8 *tmp, *pos; |
| 330 | size_t tmplen; |
| 331 | |
| 332 | tmplen = serverid_len + 1 + peerid_len + 1 + eap_len; |
| 333 | tmp = os_malloc(tmplen); |
| 334 | if (tmp == NULL) |
| 335 | return -1; |
| 336 | pos = tmp; |
| 337 | if (peer) { |
| 338 | if (peerid) { |
| 339 | os_memcpy(pos, peerid, peerid_len); |
| 340 | pos += peerid_len; |
| 341 | } |
| 342 | *pos++ = 0x00; |
| 343 | if (serverid) { |
| 344 | os_memcpy(pos, serverid, serverid_len); |
| 345 | pos += serverid_len; |
| 346 | } |
| 347 | *pos++ = 0x00; |
| 348 | |
| 349 | os_memcpy(_rand, rand_s, EAP_SAKE_RAND_LEN); |
| 350 | os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_p, |
| 351 | EAP_SAKE_RAND_LEN); |
| 352 | } else { |
| 353 | if (serverid) { |
| 354 | os_memcpy(pos, serverid, serverid_len); |
| 355 | pos += serverid_len; |
| 356 | } |
| 357 | *pos++ = 0x00; |
| 358 | if (peerid) { |
| 359 | os_memcpy(pos, peerid, peerid_len); |
| 360 | pos += peerid_len; |
| 361 | } |
| 362 | *pos++ = 0x00; |
| 363 | |
| 364 | os_memcpy(_rand, rand_p, EAP_SAKE_RAND_LEN); |
| 365 | os_memcpy(_rand + EAP_SAKE_RAND_LEN, rand_s, |
| 366 | EAP_SAKE_RAND_LEN); |
| 367 | } |
| 368 | |
| 369 | os_memcpy(pos, eap, eap_len); |
| 370 | os_memset(pos + (mic_pos - eap), 0, EAP_SAKE_MIC_LEN); |
| 371 | |
| 372 | eap_sake_kdf(tek_auth, EAP_SAKE_TEK_AUTH_LEN, |
| 373 | peer ? "Peer MIC" : "Server MIC", |
| 374 | _rand, 2 * EAP_SAKE_RAND_LEN, tmp, tmplen, |
| 375 | mic, EAP_SAKE_MIC_LEN); |
| 376 | |
| 377 | os_free(tmp); |
| 378 | |
| 379 | return 0; |
| 380 | } |