src/eap_server/eap_server_ikev2.c

   1 /*
   2  * EAP-IKEv2 server (RFC 5106)
   3  * Copyright (c) 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 "eap_i.h"
  13 #include "eap_common/eap_ikev2_common.h"
  14 #include "ikev2.h"
  15
  16
  17 struct eap_ikev2_data {
  18         struct ikev2_initiator_data ikev2;
  19         enum { MSG, FRAG_ACK, WAIT_FRAG_ACK, DONE, FAIL } state;
  20         struct wpabuf *in_buf;
  21         struct wpabuf *out_buf;
  22         size_t out_used;
  23         size_t fragment_size;
  24         int keys_ready;
  25         u8 keymat[EAP_MSK_LEN + EAP_EMSK_LEN];
  26         int keymat_ok;
  27 };
  28
  29
  30 static const u8 * eap_ikev2_get_shared_secret(void *ctx, const u8 *IDr,
  31                                               size_t IDr_len,
  32                                               size_t *secret_len)
  33 {
  34         struct eap_sm *sm = ctx;
  35
  36         if (IDr == NULL) {
  37                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: No IDr received - default "
  38                            "to user identity from EAP-Identity");
  39                 IDr = sm->identity;
  40                 IDr_len = sm->identity_len;
  41         }
  42
  43         if (eap_user_get(sm, IDr, IDr_len, 0) < 0 || sm->user == NULL ||
  44             sm->user->password == NULL) {
  45                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: No user entry found");
  46                 return NULL;
  47         }
  48
  49         *secret_len = sm->user->password_len;
  50         return sm->user->password;
  51 }
  52
  53
  54 static const char * eap_ikev2_state_txt(int state)
  55 {
  56         switch (state) {
  57         case MSG:
  58                 return "MSG";
  59         case FRAG_ACK:
  60                 return "FRAG_ACK";
  61         case WAIT_FRAG_ACK:
  62                 return "WAIT_FRAG_ACK";
  63         case DONE:
  64                 return "DONE";
  65         case FAIL:
  66                 return "FAIL";
  67         default:
  68                 return "?";
  69         }
  70 }
  71
  72
  73 static void eap_ikev2_state(struct eap_ikev2_data *data, int state)
  74 {
  75         wpa_printf(MSG_DEBUG, "EAP-IKEV2: %s -> %s",
  76                    eap_ikev2_state_txt(data->state),
  77                    eap_ikev2_state_txt(state));
  78         data->state = state;
  79 }
  80
  81
  82 static void * eap_ikev2_init(struct eap_sm *sm)
  83 {
  84         struct eap_ikev2_data *data;
  85
  86         data = os_zalloc(sizeof(*data));
  87         if (data == NULL)
  88                 return NULL;
  89         data->state = MSG;
  90         data->fragment_size = sm->fragment_size > 0 ? sm->fragment_size :
  91                 IKEV2_FRAGMENT_SIZE;
  92         data->ikev2.state = SA_INIT;
  93         data->ikev2.peer_auth = PEER_AUTH_SECRET;
  94         data->ikev2.key_pad = (u8 *) os_strdup("Key Pad for EAP-IKEv2");
  95         if (data->ikev2.key_pad == NULL)
  96                 goto failed;
  97         data->ikev2.key_pad_len = 21;
  98
  99         /* TODO: make proposals configurable */
 100         data->ikev2.proposal.proposal_num = 1;
 101         data->ikev2.proposal.integ = AUTH_HMAC_SHA1_96;
 102         data->ikev2.proposal.prf = PRF_HMAC_SHA1;
 103         data->ikev2.proposal.encr = ENCR_AES_CBC;
 104         data->ikev2.proposal.dh = DH_GROUP2_1024BIT_MODP;
 105
 106         data->ikev2.IDi = os_malloc(sm->server_id_len);
 107         if (data->ikev2.IDi == NULL)
 108                 goto failed;
 109         os_memcpy(data->ikev2.IDi, sm->server_id, sm->server_id_len);
 110         data->ikev2.IDi_len = sm->server_id_len;
 111
 112         data->ikev2.get_shared_secret = eap_ikev2_get_shared_secret;
 113         data->ikev2.cb_ctx = sm;
 114
 115         return data;
 116
 117 failed:
 118         ikev2_initiator_deinit(&data->ikev2);
 119         os_free(data);
 120         return NULL;
 121 }
 122
 123
 124 static void eap_ikev2_reset(struct eap_sm *sm, void *priv)
 125 {
 126         struct eap_ikev2_data *data = priv;
 127         wpabuf_free(data->in_buf);
 128         wpabuf_free(data->out_buf);
 129         ikev2_initiator_deinit(&data->ikev2);
 130         bin_clear_free(data, sizeof(*data));
 131 }
 132
 133
 134 static struct wpabuf * eap_ikev2_build_msg(struct eap_ikev2_data *data, u8 id)
 135 {
 136         struct wpabuf *req;
 137         u8 flags;
 138         size_t send_len, plen, icv_len = 0;
 139
 140         wpa_printf(MSG_DEBUG, "EAP-IKEV2: Generating Request");
 141
 142         flags = 0;
 143         send_len = wpabuf_len(data->out_buf) - data->out_used;
 144         if (1 + send_len > data->fragment_size) {
 145                 send_len = data->fragment_size - 1;
 146                 flags |= IKEV2_FLAGS_MORE_FRAGMENTS;
 147                 if (data->out_used == 0) {
 148                         flags |= IKEV2_FLAGS_LENGTH_INCLUDED;
 149                         send_len -= 4;
 150                 }
 151         }
 152
 153         plen = 1 + send_len;
 154         if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
 155                 plen += 4;
 156         if (data->keys_ready) {
 157                 const struct ikev2_integ_alg *integ;
 158                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Add Integrity Checksum "
 159                            "Data");
 160                 flags |= IKEV2_FLAGS_ICV_INCLUDED;
 161                 integ = ikev2_get_integ(data->ikev2.proposal.integ);
 162                 if (integ == NULL) {
 163                         wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unknown INTEG "
 164                                    "transform / cannot generate ICV");
 165                         return NULL;
 166                 }
 167                 icv_len = integ->hash_len;
 168
 169                 plen += icv_len;
 170         }
 171         req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, plen,
 172                             EAP_CODE_REQUEST, id);
 173         if (req == NULL)
 174                 return NULL;
 175
 176         wpabuf_put_u8(req, flags); /* Flags */
 177         if (flags & IKEV2_FLAGS_LENGTH_INCLUDED)
 178                 wpabuf_put_be32(req, wpabuf_len(data->out_buf));
 179
 180         wpabuf_put_data(req, wpabuf_head_u8(data->out_buf) + data->out_used,
 181                         send_len);
 182         data->out_used += send_len;
 183
 184         if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
 185                 const u8 *msg = wpabuf_head(req);
 186                 size_t len = wpabuf_len(req);
 187                 ikev2_integ_hash(data->ikev2.proposal.integ,
 188                                  data->ikev2.keys.SK_ai,
 189                                  data->ikev2.keys.SK_integ_len,
 190                                  msg, len, wpabuf_put(req, icv_len));
 191         }
 192
 193         if (data->out_used == wpabuf_len(data->out_buf)) {
 194                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
 195                            "(message sent completely)",
 196                            (unsigned long) send_len);
 197                 wpabuf_free(data->out_buf);
 198                 data->out_buf = NULL;
 199                 data->out_used = 0;
 200         } else {
 201                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Sending out %lu bytes "
 202                            "(%lu more to send)", (unsigned long) send_len,
 203                            (unsigned long) wpabuf_len(data->out_buf) -
 204                            data->out_used);
 205                 eap_ikev2_state(data, WAIT_FRAG_ACK);
 206         }
 207
 208         return req;
 209 }
 210
 211
 212 static struct wpabuf * eap_ikev2_buildReq(struct eap_sm *sm, void *priv, u8 id)
 213 {
 214         struct eap_ikev2_data *data = priv;
 215
 216         switch (data->state) {
 217         case MSG:
 218                 if (data->out_buf == NULL) {
 219                         data->out_buf = ikev2_initiator_build(&data->ikev2);
 220                         if (data->out_buf == NULL) {
 221                                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to "
 222                                            "generate IKEv2 message");
 223                                 return NULL;
 224                         }
 225                         data->out_used = 0;
 226                 }
 227                 /* pass through */
 228         case WAIT_FRAG_ACK:
 229                 return eap_ikev2_build_msg(data, id);
 230         case FRAG_ACK:
 231                 return eap_ikev2_build_frag_ack(id, EAP_CODE_REQUEST);
 232         default:
 233                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unexpected state %d in "
 234                            "buildReq", data->state);
 235                 return NULL;
 236         }
 237 }
 238
 239
 240 static Boolean eap_ikev2_check(struct eap_sm *sm, void *priv,
 241                                struct wpabuf *respData)
 242 {
 243         const u8 *pos;
 244         size_t len;
 245
 246         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, respData,
 247                                &len);
 248         if (pos == NULL) {
 249                 wpa_printf(MSG_INFO, "EAP-IKEV2: Invalid frame");
 250                 return TRUE;
 251         }
 252
 253         return FALSE;
 254 }
 255
 256
 257 static int eap_ikev2_process_icv(struct eap_ikev2_data *data,
 258                                  const struct wpabuf *respData,
 259                                  u8 flags, const u8 *pos, const u8 **end,
 260                                  int frag_ack)
 261 {
 262         if (flags & IKEV2_FLAGS_ICV_INCLUDED) {
 263                 int icv_len = eap_ikev2_validate_icv(
 264                         data->ikev2.proposal.integ, &data->ikev2.keys, 0,
 265                         respData, pos, *end);
 266                 if (icv_len < 0)
 267                         return -1;
 268                 /* Hide Integrity Checksum Data from further processing */
 269                 *end -= icv_len;
 270         } else if (data->keys_ready && !frag_ack) {
 271                 wpa_printf(MSG_INFO, "EAP-IKEV2: The message should have "
 272                            "included integrity checksum");
 273                 return -1;
 274         }
 275
 276         return 0;
 277 }
 278
 279
 280 static int eap_ikev2_process_cont(struct eap_ikev2_data *data,
 281                                   const u8 *buf, size_t len)
 282 {
 283         /* Process continuation of a pending message */
 284         if (len > wpabuf_tailroom(data->in_buf)) {
 285                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment overflow");
 286                 eap_ikev2_state(data, FAIL);
 287                 return -1;
 288         }
 289
 290         wpabuf_put_data(data->in_buf, buf, len);
 291         wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes, waiting for %lu "
 292                    "bytes more", (unsigned long) len,
 293                    (unsigned long) wpabuf_tailroom(data->in_buf));
 294
 295         return 0;
 296 }
 297
 298
 299 static int eap_ikev2_process_fragment(struct eap_ikev2_data *data,
 300                                       u8 flags, u32 message_length,
 301                                       const u8 *buf, size_t len)
 302 {
 303         /* Process a fragment that is not the last one of the message */
 304         if (data->in_buf == NULL && !(flags & IKEV2_FLAGS_LENGTH_INCLUDED)) {
 305                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: No Message Length field in "
 306                            "a fragmented packet");
 307                 return -1;
 308         }
 309
 310         if (data->in_buf == NULL) {
 311                 /* First fragment of the message */
 312                 data->in_buf = wpabuf_alloc(message_length);
 313                 if (data->in_buf == NULL) {
 314                         wpa_printf(MSG_DEBUG, "EAP-IKEV2: No memory for "
 315                                    "message");
 316                         return -1;
 317                 }
 318                 wpabuf_put_data(data->in_buf, buf, len);
 319                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received %lu bytes in first "
 320                            "fragment, waiting for %lu bytes more",
 321                            (unsigned long) len,
 322                            (unsigned long) wpabuf_tailroom(data->in_buf));
 323         }
 324
 325         return 0;
 326 }
 327
 328
 329 static int eap_ikev2_server_keymat(struct eap_ikev2_data *data)
 330 {
 331         if (eap_ikev2_derive_keymat(
 332                     data->ikev2.proposal.prf, &data->ikev2.keys,
 333                     data->ikev2.i_nonce, data->ikev2.i_nonce_len,
 334                     data->ikev2.r_nonce, data->ikev2.r_nonce_len,
 335                     data->keymat) < 0) {
 336                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Failed to derive "
 337                            "key material");
 338                 return -1;
 339         }
 340         data->keymat_ok = 1;
 341         return 0;
 342 }
 343
 344
 345 static void eap_ikev2_process(struct eap_sm *sm, void *priv,
 346                               struct wpabuf *respData)
 347 {
 348         struct eap_ikev2_data *data = priv;
 349         const u8 *start, *pos, *end;
 350         size_t len;
 351         u8 flags;
 352         u32 message_length = 0;
 353         struct wpabuf tmpbuf;
 354
 355         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_IKEV2, respData,
 356                                &len);
 357         if (pos == NULL)
 358                 return; /* Should not happen; message already verified */
 359
 360         start = pos;
 361         end = start + len;
 362
 363         if (len == 0) {
 364                 /* fragment ack */
 365                 flags = 0;
 366         } else
 367                 flags = *pos++;
 368
 369         if (eap_ikev2_process_icv(data, respData, flags, pos, &end,
 370                                   data->state == WAIT_FRAG_ACK && len == 0) < 0)
 371         {
 372                 eap_ikev2_state(data, FAIL);
 373                 return;
 374         }
 375
 376         if (flags & IKEV2_FLAGS_LENGTH_INCLUDED) {
 377                 if (end - pos < 4) {
 378                         wpa_printf(MSG_DEBUG, "EAP-IKEV2: Message underflow");
 379                         eap_ikev2_state(data, FAIL);
 380                         return;
 381                 }
 382                 message_length = WPA_GET_BE32(pos);
 383                 pos += 4;
 384
 385                 if (message_length < (u32) (end - pos)) {
 386                         wpa_printf(MSG_DEBUG, "EAP-IKEV2: Invalid Message "
 387                                    "Length (%d; %ld remaining in this msg)",
 388                                    message_length, (long) (end - pos));
 389                         eap_ikev2_state(data, FAIL);
 390                         return;
 391                 }
 392         }
 393         wpa_printf(MSG_DEBUG, "EAP-IKEV2: Received packet: Flags 0x%x "
 394                    "Message Length %u", flags, message_length);
 395
 396         if (data->state == WAIT_FRAG_ACK) {
 397                 if (len != 0) {
 398                         wpa_printf(MSG_DEBUG, "EAP-IKEV2: Unexpected payload "
 399                                    "in WAIT_FRAG_ACK state");
 400                         eap_ikev2_state(data, FAIL);
 401                         return;
 402                 }
 403                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Fragment acknowledged");
 404                 eap_ikev2_state(data, MSG);
 405                 return;
 406         }
 407
 408         if (data->in_buf && eap_ikev2_process_cont(data, pos, end - pos) < 0) {
 409                 eap_ikev2_state(data, FAIL);
 410                 return;
 411         }
 412
 413         if (flags & IKEV2_FLAGS_MORE_FRAGMENTS) {
 414                 if (eap_ikev2_process_fragment(data, flags, message_length,
 415                                                pos, end - pos) < 0)
 416                         eap_ikev2_state(data, FAIL);
 417                 else
 418                         eap_ikev2_state(data, FRAG_ACK);
 419                 return;
 420         } else if (data->state == FRAG_ACK) {
 421                 wpa_printf(MSG_DEBUG, "EAP-TNC: All fragments received");
 422                 data->state = MSG;
 423         }
 424
 425         if (data->in_buf == NULL) {
 426                 /* Wrap unfragmented messages as wpabuf without extra copy */
 427                 wpabuf_set(&tmpbuf, pos, end - pos);
 428                 data->in_buf = &tmpbuf;
 429         }
 430
 431         if (ikev2_initiator_process(&data->ikev2, data->in_buf) < 0) {
 432                 if (data->in_buf == &tmpbuf)
 433                         data->in_buf = NULL;
 434                 eap_ikev2_state(data, FAIL);
 435                 return;
 436         }
 437
 438         switch (data->ikev2.state) {
 439         case SA_AUTH:
 440                 /* SA_INIT was sent out, so message have to be
 441                  * integrity protected from now on. */
 442                 data->keys_ready = 1;
 443                 break;
 444         case IKEV2_DONE:
 445                 if (data->state == FAIL)
 446                         break;
 447                 wpa_printf(MSG_DEBUG, "EAP-IKEV2: Authentication completed "
 448                            "successfully");
 449                 if (eap_ikev2_server_keymat(data))
 450                         break;
 451                 eap_ikev2_state(data, DONE);
 452                 break;
 453         default:
 454                 break;
 455         }
 456
 457         if (data->in_buf != &tmpbuf)
 458                 wpabuf_free(data->in_buf);
 459         data->in_buf = NULL;
 460 }
 461
 462
 463 static Boolean eap_ikev2_isDone(struct eap_sm *sm, void *priv)
 464 {
 465         struct eap_ikev2_data *data = priv;
 466         return data->state == DONE || data->state == FAIL;
 467 }
 468
 469
 470 static Boolean eap_ikev2_isSuccess(struct eap_sm *sm, void *priv)
 471 {
 472         struct eap_ikev2_data *data = priv;
 473         return data->state == DONE && data->ikev2.state == IKEV2_DONE &&
 474                 data->keymat_ok;
 475 }
 476
 477
 478 static u8 * eap_ikev2_getKey(struct eap_sm *sm, void *priv, size_t *len)
 479 {
 480         struct eap_ikev2_data *data = priv;
 481         u8 *key;
 482
 483         if (data->state != DONE || !data->keymat_ok)
 484                 return NULL;
 485
 486         key = os_malloc(EAP_MSK_LEN);
 487         if (key) {
 488                 os_memcpy(key, data->keymat, EAP_MSK_LEN);
 489                 *len = EAP_MSK_LEN;
 490         }
 491
 492         return key;
 493 }
 494
 495
 496 static u8 * eap_ikev2_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 497 {
 498         struct eap_ikev2_data *data = priv;
 499         u8 *key;
 500
 501         if (data->state != DONE || !data->keymat_ok)
 502                 return NULL;
 503
 504         key = os_malloc(EAP_EMSK_LEN);
 505         if (key) {
 506                 os_memcpy(key, data->keymat + EAP_MSK_LEN, EAP_EMSK_LEN);
 507                 *len = EAP_EMSK_LEN;
 508         }
 509
 510         return key;
 511 }
 512
 513
 514 int eap_server_ikev2_register(void)
 515 {
 516         struct eap_method *eap;
 517         int ret;
 518
 519         eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
 520                                       EAP_VENDOR_IETF, EAP_TYPE_IKEV2,
 521                                       "IKEV2");
 522         if (eap == NULL)
 523                 return -1;
 524
 525         eap->init = eap_ikev2_init;
 526         eap->reset = eap_ikev2_reset;
 527         eap->buildReq = eap_ikev2_buildReq;
 528         eap->check = eap_ikev2_check;
 529         eap->process = eap_ikev2_process;
 530         eap->isDone = eap_ikev2_isDone;
 531         eap->getKey = eap_ikev2_getKey;
 532         eap->isSuccess = eap_ikev2_isSuccess;
 533         eap->get_emsk = eap_ikev2_get_emsk;
 534
 535         ret = eap_server_method_register(eap);
 536         if (ret)
 537                 eap_server_method_free(eap);
 538         return ret;
 539 }