contrib/wpa/src/eap_server/eap_server_pwd.c

   1 /*
   2  * hostapd / EAP-pwd (RFC 5931) server
   3  * Copyright (c) 2010, Dan Harkins <dharkins@lounge.org>
   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 "crypto/sha256.h"
  13 #include "eap_server/eap_i.h"
  14 #include "eap_common/eap_pwd_common.h"
  15
  16
  17 struct eap_pwd_data {
  18         enum {
  19                 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
  20         } state;
  21         u8 *id_peer;
  22         size_t id_peer_len;
  23         u8 *id_server;
  24         size_t id_server_len;
  25         u8 *password;
  26         size_t password_len;
  27         u32 token;
  28         u16 group_num;
  29         EAP_PWD_group *grp;
  30
  31         struct wpabuf *inbuf;
  32         size_t in_frag_pos;
  33         struct wpabuf *outbuf;
  34         size_t out_frag_pos;
  35         size_t mtu;
  36
  37         BIGNUM *k;
  38         BIGNUM *private_value;
  39         BIGNUM *peer_scalar;
  40         BIGNUM *my_scalar;
  41         EC_POINT *my_element;
  42         EC_POINT *peer_element;
  43
  44         u8 my_confirm[SHA256_MAC_LEN];
  45
  46         u8 msk[EAP_MSK_LEN];
  47         u8 emsk[EAP_EMSK_LEN];
  48         u8 session_id[1 + SHA256_MAC_LEN];
  49
  50         BN_CTX *bnctx;
  51 };
  52
  53
  54 static const char * eap_pwd_state_txt(int state)
  55 {
  56         switch (state) {
  57         case PWD_ID_Req:
  58                 return "PWD-ID-Req";
  59         case PWD_Commit_Req:
  60                 return "PWD-Commit-Req";
  61         case PWD_Confirm_Req:
  62                 return "PWD-Confirm-Req";
  63         case SUCCESS:
  64                 return "SUCCESS";
  65         case FAILURE:
  66                 return "FAILURE";
  67         default:
  68                 return "PWD-Unk";
  69         }
  70 }
  71
  72
  73 static void eap_pwd_state(struct eap_pwd_data *data, int state)
  74 {
  75         wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
  76                    eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
  77         data->state = state;
  78 }
  79
  80
  81 static void * eap_pwd_init(struct eap_sm *sm)
  82 {
  83         struct eap_pwd_data *data;
  84
  85         if (sm->user == NULL || sm->user->password == NULL ||
  86             sm->user->password_len == 0) {
  87                 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
  88                            "configured");
  89                 return NULL;
  90         }
  91
  92         data = os_zalloc(sizeof(*data));
  93         if (data == NULL)
  94                 return NULL;
  95
  96         data->group_num = sm->pwd_group;
  97         wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
  98                    data->group_num);
  99         data->state = PWD_ID_Req;
 100
 101         data->id_server = (u8 *) os_strdup("server");
 102         if (data->id_server)
 103                 data->id_server_len = os_strlen((char *) data->id_server);
 104
 105         data->password = os_malloc(sm->user->password_len);
 106         if (data->password == NULL) {
 107                 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
 108                            "fail");
 109                 bin_clear_free(data->id_server, data->id_server_len);
 110                 os_free(data);
 111                 return NULL;
 112         }
 113         data->password_len = sm->user->password_len;
 114         os_memcpy(data->password, sm->user->password, data->password_len);
 115
 116         data->bnctx = BN_CTX_new();
 117         if (data->bnctx == NULL) {
 118                 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
 119                 bin_clear_free(data->password, data->password_len);
 120                 bin_clear_free(data->id_server, data->id_server_len);
 121                 os_free(data);
 122                 return NULL;
 123         }
 124
 125         data->in_frag_pos = data->out_frag_pos = 0;
 126         data->inbuf = data->outbuf = NULL;
 127         /* use default MTU from RFC 5931 if not configured otherwise */
 128         data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020;
 129
 130         return data;
 131 }
 132
 133
 134 static void eap_pwd_reset(struct eap_sm *sm, void *priv)
 135 {
 136         struct eap_pwd_data *data = priv;
 137
 138         BN_clear_free(data->private_value);
 139         BN_clear_free(data->peer_scalar);
 140         BN_clear_free(data->my_scalar);
 141         BN_clear_free(data->k);
 142         BN_CTX_free(data->bnctx);
 143         EC_POINT_clear_free(data->my_element);
 144         EC_POINT_clear_free(data->peer_element);
 145         bin_clear_free(data->id_peer, data->id_peer_len);
 146         bin_clear_free(data->id_server, data->id_server_len);
 147         bin_clear_free(data->password, data->password_len);
 148         if (data->grp) {
 149                 EC_GROUP_free(data->grp->group);
 150                 EC_POINT_clear_free(data->grp->pwe);
 151                 BN_clear_free(data->grp->order);
 152                 BN_clear_free(data->grp->prime);
 153                 os_free(data->grp);
 154         }
 155         wpabuf_free(data->inbuf);
 156         wpabuf_free(data->outbuf);
 157         bin_clear_free(data, sizeof(*data));
 158 }
 159
 160
 161 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
 162                                  u8 id)
 163 {
 164         wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
 165         /*
 166          * if we're fragmenting then we already have an id request, just return
 167          */
 168         if (data->out_frag_pos)
 169                 return;
 170
 171         data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
 172                                     data->id_server_len);
 173         if (data->outbuf == NULL) {
 174                 eap_pwd_state(data, FAILURE);
 175                 return;
 176         }
 177
 178         /* an lfsr is good enough to generate unpredictable tokens */
 179         data->token = os_random();
 180         wpabuf_put_be16(data->outbuf, data->group_num);
 181         wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
 182         wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
 183         wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
 184         wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE);
 185         wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
 186 }
 187
 188
 189 static void eap_pwd_build_commit_req(struct eap_sm *sm,
 190                                      struct eap_pwd_data *data, u8 id)
 191 {
 192         BIGNUM *mask = NULL, *x = NULL, *y = NULL;
 193         u8 *scalar = NULL, *element = NULL;
 194         u16 offset;
 195
 196         wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
 197         /*
 198          * if we're fragmenting then we already have an commit request, just
 199          * return
 200          */
 201         if (data->out_frag_pos)
 202                 return;
 203
 204         if (((data->private_value = BN_new()) == NULL) ||
 205             ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
 206             ((data->my_scalar = BN_new()) == NULL) ||
 207             ((mask = BN_new()) == NULL)) {
 208                 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
 209                            "fail");
 210                 goto fin;
 211         }
 212
 213         if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
 214             BN_rand_range(mask, data->grp->order) != 1 ||
 215             BN_add(data->my_scalar, data->private_value, mask) != 1 ||
 216             BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
 217                    data->bnctx) != 1) {
 218                 wpa_printf(MSG_INFO,
 219                            "EAP-pwd (server): unable to get randomness");
 220                 goto fin;
 221         }
 222
 223         if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
 224                           data->grp->pwe, mask, data->bnctx)) {
 225                 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
 226                            "fail");
 227                 eap_pwd_state(data, FAILURE);
 228                 goto fin;
 229         }
 230
 231         if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
 232         {
 233                 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
 234                            "fail");
 235                 goto fin;
 236         }
 237         BN_clear_free(mask);
 238
 239         if (((x = BN_new()) == NULL) ||
 240             ((y = BN_new()) == NULL)) {
 241                 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
 242                            "fail");
 243                 goto fin;
 244         }
 245         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 246                                                  data->my_element, x, y,
 247                                                  data->bnctx)) {
 248                 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
 249                            "fail");
 250                 goto fin;
 251         }
 252
 253         if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
 254             ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
 255              NULL)) {
 256                 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
 257                 goto fin;
 258         }
 259
 260         /*
 261          * bignums occupy as little memory as possible so one that is
 262          * sufficiently smaller than the prime or order might need pre-pending
 263          * with zeros.
 264          */
 265         os_memset(scalar, 0, BN_num_bytes(data->grp->order));
 266         os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
 267         offset = BN_num_bytes(data->grp->order) -
 268                 BN_num_bytes(data->my_scalar);
 269         BN_bn2bin(data->my_scalar, scalar + offset);
 270
 271         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 272         BN_bn2bin(x, element + offset);
 273         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 274         BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
 275
 276         data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
 277                                     BN_num_bytes(data->grp->order));
 278         if (data->outbuf == NULL)
 279                 goto fin;
 280
 281         /* We send the element as (x,y) followed by the scalar */
 282         wpabuf_put_data(data->outbuf, element,
 283                         2 * BN_num_bytes(data->grp->prime));
 284         wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
 285
 286 fin:
 287         os_free(scalar);
 288         os_free(element);
 289         BN_clear_free(x);
 290         BN_clear_free(y);
 291         if (data->outbuf == NULL)
 292                 eap_pwd_state(data, FAILURE);
 293 }
 294
 295
 296 static void eap_pwd_build_confirm_req(struct eap_sm *sm,
 297                                       struct eap_pwd_data *data, u8 id)
 298 {
 299         BIGNUM *x = NULL, *y = NULL;
 300         struct crypto_hash *hash;
 301         u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
 302         u16 grp;
 303         int offset;
 304
 305         wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
 306         /*
 307          * if we're fragmenting then we already have an confirm request, just
 308          * return
 309          */
 310         if (data->out_frag_pos)
 311                 return;
 312
 313         /* Each component of the cruft will be at most as big as the prime */
 314         if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
 315             ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
 316                 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
 317                            "fail");
 318                 goto fin;
 319         }
 320
 321         /*
 322          * commit is H(k | server_element | server_scalar | peer_element |
 323          *             peer_scalar | ciphersuite)
 324          */
 325         hash = eap_pwd_h_init();
 326         if (hash == NULL)
 327                 goto fin;
 328
 329         /*
 330          * Zero the memory each time because this is mod prime math and some
 331          * value may start with a few zeros and the previous one did not.
 332          *
 333          * First is k
 334          */
 335         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 336         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
 337         BN_bn2bin(data->k, cruft + offset);
 338         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 339
 340         /* server element: x, y */
 341         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 342                                                  data->my_element, x, y,
 343                                                  data->bnctx)) {
 344                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 345                            "assignment fail");
 346                 goto fin;
 347         }
 348
 349         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 350         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 351         BN_bn2bin(x, cruft + offset);
 352         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 353         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 354         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 355         BN_bn2bin(y, cruft + offset);
 356         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 357
 358         /* server scalar */
 359         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 360         offset = BN_num_bytes(data->grp->order) -
 361                 BN_num_bytes(data->my_scalar);
 362         BN_bn2bin(data->my_scalar, cruft + offset);
 363         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 364
 365         /* peer element: x, y */
 366         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 367                                                  data->peer_element, x, y,
 368                                                  data->bnctx)) {
 369                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 370                            "assignment fail");
 371                 goto fin;
 372         }
 373
 374         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 375         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 376         BN_bn2bin(x, cruft + offset);
 377         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 378         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 379         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 380         BN_bn2bin(y, cruft + offset);
 381         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 382
 383         /* peer scalar */
 384         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 385         offset = BN_num_bytes(data->grp->order) -
 386                 BN_num_bytes(data->peer_scalar);
 387         BN_bn2bin(data->peer_scalar, cruft + offset);
 388         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 389
 390         /* ciphersuite */
 391         grp = htons(data->group_num);
 392         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 393         ptr = cruft;
 394         os_memcpy(ptr, &grp, sizeof(u16));
 395         ptr += sizeof(u16);
 396         *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
 397         ptr += sizeof(u8);
 398         *ptr = EAP_PWD_DEFAULT_PRF;
 399         ptr += sizeof(u8);
 400         eap_pwd_h_update(hash, cruft, ptr - cruft);
 401
 402         /* all done with the random function */
 403         eap_pwd_h_final(hash, conf);
 404         os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
 405
 406         data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
 407         if (data->outbuf == NULL)
 408                 goto fin;
 409
 410         wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
 411
 412 fin:
 413         bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
 414         BN_clear_free(x);
 415         BN_clear_free(y);
 416         if (data->outbuf == NULL)
 417                 eap_pwd_state(data, FAILURE);
 418 }
 419
 420
 421 static struct wpabuf *
 422 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
 423 {
 424         struct eap_pwd_data *data = priv;
 425         struct wpabuf *req;
 426         u8 lm_exch;
 427         const u8 *buf;
 428         u16 totlen = 0;
 429         size_t len;
 430
 431         /*
 432          * if we're buffering response fragments then just ACK
 433          */
 434         if (data->in_frag_pos) {
 435                 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
 436                 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
 437                                     EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
 438                 if (req == NULL) {
 439                         eap_pwd_state(data, FAILURE);
 440                         return NULL;
 441                 }
 442                 switch (data->state) {
 443                 case PWD_ID_Req:
 444                         wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
 445                         break;
 446                 case PWD_Commit_Req:
 447                         wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
 448                         break;
 449                 case PWD_Confirm_Req:
 450                         wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
 451                         break;
 452                 default:
 453                         eap_pwd_state(data, FAILURE);   /* just to be sure */
 454                         wpabuf_free(req);
 455                         return NULL;
 456                 }
 457                 return req;
 458         }
 459
 460         /*
 461          * build the data portion of a request
 462          */
 463         switch (data->state) {
 464         case PWD_ID_Req:
 465                 eap_pwd_build_id_req(sm, data, id);
 466                 lm_exch = EAP_PWD_OPCODE_ID_EXCH;
 467                 break;
 468         case PWD_Commit_Req:
 469                 eap_pwd_build_commit_req(sm, data, id);
 470                 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
 471                 break;
 472         case PWD_Confirm_Req:
 473                 eap_pwd_build_confirm_req(sm, data, id);
 474                 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
 475                 break;
 476         default:
 477                 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
 478                            data->state);
 479                 eap_pwd_state(data, FAILURE);
 480                 lm_exch = 0;    /* hush now, sweet compiler */
 481                 break;
 482         }
 483
 484         if (data->state == FAILURE)
 485                 return NULL;
 486
 487         /*
 488          * determine whether that data needs to be fragmented
 489          */
 490         len = wpabuf_len(data->outbuf) - data->out_frag_pos;
 491         if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
 492                 len = data->mtu - EAP_PWD_HDR_SIZE;
 493                 EAP_PWD_SET_MORE_BIT(lm_exch);
 494                 /*
 495                  * if this is the first fragment, need to set the M bit
 496                  * and add the total length to the eap_pwd_hdr
 497                  */
 498                 if (data->out_frag_pos == 0) {
 499                         EAP_PWD_SET_LENGTH_BIT(lm_exch);
 500                         totlen = wpabuf_len(data->outbuf) +
 501                                 EAP_PWD_HDR_SIZE + sizeof(u16);
 502                         len -= sizeof(u16);
 503                         wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
 504                                    "total length = %d", totlen);
 505                 }
 506                 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
 507                            (int) len);
 508         }
 509
 510         /*
 511          * alloc an eap request and populate it with the data
 512          */
 513         req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
 514                             EAP_PWD_HDR_SIZE + len +
 515                             (totlen ? sizeof(u16) : 0),
 516                             EAP_CODE_REQUEST, id);
 517         if (req == NULL) {
 518                 eap_pwd_state(data, FAILURE);
 519                 return NULL;
 520         }
 521
 522         wpabuf_put_u8(req, lm_exch);
 523         if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
 524                 wpabuf_put_be16(req, totlen);
 525
 526         buf = wpabuf_head_u8(data->outbuf);
 527         wpabuf_put_data(req, buf + data->out_frag_pos, len);
 528         data->out_frag_pos += len;
 529         /*
 530          * either not fragged or last fragment, either way free up the data
 531          */
 532         if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
 533                 wpabuf_free(data->outbuf);
 534                 data->outbuf = NULL;
 535                 data->out_frag_pos = 0;
 536         }
 537
 538         return req;
 539 }
 540
 541
 542 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
 543                              struct wpabuf *respData)
 544 {
 545         struct eap_pwd_data *data = priv;
 546         const u8 *pos;
 547         size_t len;
 548
 549         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
 550         if (pos == NULL || len < 1) {
 551                 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
 552                 return TRUE;
 553         }
 554
 555         wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
 556                    EAP_PWD_GET_EXCHANGE(*pos), (int) len);
 557
 558         if (data->state == PWD_ID_Req &&
 559             ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
 560                 return FALSE;
 561
 562         if (data->state == PWD_Commit_Req &&
 563             ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
 564                 return FALSE;
 565
 566         if (data->state == PWD_Confirm_Req &&
 567             ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
 568                 return FALSE;
 569
 570         wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
 571                    *pos, data->state);
 572
 573         return TRUE;
 574 }
 575
 576
 577 static void eap_pwd_process_id_resp(struct eap_sm *sm,
 578                                     struct eap_pwd_data *data,
 579                                     const u8 *payload, size_t payload_len)
 580 {
 581         struct eap_pwd_id *id;
 582
 583         if (payload_len < sizeof(struct eap_pwd_id)) {
 584                 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
 585                 return;
 586         }
 587
 588         id = (struct eap_pwd_id *) payload;
 589         if ((data->group_num != be_to_host16(id->group_num)) ||
 590             (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
 591             (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
 592             (id->prf != EAP_PWD_DEFAULT_PRF)) {
 593                 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
 594                 eap_pwd_state(data, FAILURE);
 595                 return;
 596         }
 597         data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
 598         if (data->id_peer == NULL) {
 599                 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
 600                 return;
 601         }
 602         data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
 603         os_memcpy(data->id_peer, id->identity, data->id_peer_len);
 604         wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
 605                           data->id_peer, data->id_peer_len);
 606
 607         data->grp = os_zalloc(sizeof(EAP_PWD_group));
 608         if (data->grp == NULL) {
 609                 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
 610                            "group");
 611                 return;
 612         }
 613         if (compute_password_element(data->grp, data->group_num,
 614                                      data->password, data->password_len,
 615                                      data->id_server, data->id_server_len,
 616                                      data->id_peer, data->id_peer_len,
 617                                      (u8 *) &data->token)) {
 618                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
 619                            "PWE");
 620                 return;
 621         }
 622         wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
 623                    BN_num_bits(data->grp->prime));
 624
 625         eap_pwd_state(data, PWD_Commit_Req);
 626 }
 627
 628
 629 static void
 630 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 631                             const u8 *payload, size_t payload_len)
 632 {
 633         u8 *ptr;
 634         BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
 635         EC_POINT *K = NULL, *point = NULL;
 636         int res = 0;
 637
 638         wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
 639
 640         if (((data->peer_scalar = BN_new()) == NULL) ||
 641             ((data->k = BN_new()) == NULL) ||
 642             ((cofactor = BN_new()) == NULL) ||
 643             ((x = BN_new()) == NULL) ||
 644             ((y = BN_new()) == NULL) ||
 645             ((point = EC_POINT_new(data->grp->group)) == NULL) ||
 646             ((K = EC_POINT_new(data->grp->group)) == NULL) ||
 647             ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
 648                 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
 649                            "fail");
 650                 goto fin;
 651         }
 652
 653         if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
 654                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
 655                            "cofactor for curve");
 656                 goto fin;
 657         }
 658
 659         /* element, x then y, followed by scalar */
 660         ptr = (u8 *) payload;
 661         BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
 662         ptr += BN_num_bytes(data->grp->prime);
 663         BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
 664         ptr += BN_num_bytes(data->grp->prime);
 665         BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
 666         if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
 667                                                  data->peer_element, x, y,
 668                                                  data->bnctx)) {
 669                 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
 670                            "fail");
 671                 goto fin;
 672         }
 673
 674         /* check to ensure peer's element is not in a small sub-group */
 675         if (BN_cmp(cofactor, BN_value_one())) {
 676                 if (!EC_POINT_mul(data->grp->group, point, NULL,
 677                                   data->peer_element, cofactor, NULL)) {
 678                         wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
 679                                    "multiply peer element by order");
 680                         goto fin;
 681                 }
 682                 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
 683                         wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
 684                                    "is at infinity!\n");
 685                         goto fin;
 686                 }
 687         }
 688
 689         /* compute the shared key, k */
 690         if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
 691                            data->peer_scalar, data->bnctx)) ||
 692             (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
 693                            data->bnctx)) ||
 694             (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
 695                            data->bnctx))) {
 696                 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
 697                            "fail");
 698                 goto fin;
 699         }
 700
 701         /* ensure that the shared key isn't in a small sub-group */
 702         if (BN_cmp(cofactor, BN_value_one())) {
 703                 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
 704                                   NULL)) {
 705                         wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
 706                                    "multiply shared key point by order!\n");
 707                         goto fin;
 708                 }
 709         }
 710
 711         /*
 712          * This check is strictly speaking just for the case above where
 713          * co-factor > 1 but it was suggested that even though this is probably
 714          * never going to happen it is a simple and safe check "just to be
 715          * sure" so let's be safe.
 716          */
 717         if (EC_POINT_is_at_infinity(data->grp->group, K)) {
 718                 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
 719                            "at infinity");
 720                 goto fin;
 721         }
 722         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
 723                                                  NULL, data->bnctx)) {
 724                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
 725                            "shared secret from secret point");
 726                 goto fin;
 727         }
 728         res = 1;
 729
 730 fin:
 731         EC_POINT_clear_free(K);
 732         EC_POINT_clear_free(point);
 733         BN_clear_free(cofactor);
 734         BN_clear_free(x);
 735         BN_clear_free(y);
 736
 737         if (res)
 738                 eap_pwd_state(data, PWD_Confirm_Req);
 739         else
 740                 eap_pwd_state(data, FAILURE);
 741 }
 742
 743
 744 static void
 745 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 746                              const u8 *payload, size_t payload_len)
 747 {
 748         BIGNUM *x = NULL, *y = NULL;
 749         struct crypto_hash *hash;
 750         u32 cs;
 751         u16 grp;
 752         u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
 753         int offset;
 754
 755         /* build up the ciphersuite: group | random_function | prf */
 756         grp = htons(data->group_num);
 757         ptr = (u8 *) &cs;
 758         os_memcpy(ptr, &grp, sizeof(u16));
 759         ptr += sizeof(u16);
 760         *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
 761         ptr += sizeof(u8);
 762         *ptr = EAP_PWD_DEFAULT_PRF;
 763
 764         /* each component of the cruft will be at most as big as the prime */
 765         if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
 766             ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
 767                 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
 768                 goto fin;
 769         }
 770
 771         /*
 772          * commit is H(k | peer_element | peer_scalar | server_element |
 773          *             server_scalar | ciphersuite)
 774          */
 775         hash = eap_pwd_h_init();
 776         if (hash == NULL)
 777                 goto fin;
 778
 779         /* k */
 780         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 781         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
 782         BN_bn2bin(data->k, cruft + offset);
 783         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 784
 785         /* peer element: x, y */
 786         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 787                                                  data->peer_element, x, y,
 788                                                  data->bnctx)) {
 789                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 790                            "assignment fail");
 791                 goto fin;
 792         }
 793         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 794         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 795         BN_bn2bin(x, cruft + offset);
 796         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 797         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 798         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 799         BN_bn2bin(y, cruft + offset);
 800         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 801
 802         /* peer scalar */
 803         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 804         offset = BN_num_bytes(data->grp->order) -
 805                 BN_num_bytes(data->peer_scalar);
 806         BN_bn2bin(data->peer_scalar, cruft + offset);
 807         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 808
 809         /* server element: x, y */
 810         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 811                                                  data->my_element, x, y,
 812                                                  data->bnctx)) {
 813                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 814                            "assignment fail");
 815                 goto fin;
 816         }
 817
 818         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 819         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 820         BN_bn2bin(x, cruft + offset);
 821         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 822         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 823         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 824         BN_bn2bin(y, cruft + offset);
 825         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 826
 827         /* server scalar */
 828         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 829         offset = BN_num_bytes(data->grp->order) -
 830                 BN_num_bytes(data->my_scalar);
 831         BN_bn2bin(data->my_scalar, cruft + offset);
 832         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 833
 834         /* ciphersuite */
 835         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 836         eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
 837
 838         /* all done */
 839         eap_pwd_h_final(hash, conf);
 840
 841         ptr = (u8 *) payload;
 842         if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
 843                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
 844                            "verify");
 845                 goto fin;
 846         }
 847
 848         wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
 849         if (compute_keys(data->grp, data->bnctx, data->k,
 850                          data->peer_scalar, data->my_scalar, conf,
 851                          data->my_confirm, &cs, data->msk, data->emsk,
 852                          data->session_id) < 0)
 853                 eap_pwd_state(data, FAILURE);
 854         else
 855                 eap_pwd_state(data, SUCCESS);
 856
 857 fin:
 858         bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
 859         BN_clear_free(x);
 860         BN_clear_free(y);
 861 }
 862
 863
 864 static void eap_pwd_process(struct eap_sm *sm, void *priv,
 865                             struct wpabuf *respData)
 866 {
 867         struct eap_pwd_data *data = priv;
 868         const u8 *pos;
 869         size_t len;
 870         u8 lm_exch;
 871         u16 tot_len;
 872
 873         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
 874         if ((pos == NULL) || (len < 1)) {
 875                 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
 876                            (pos == NULL) ? "is NULL" : "is not NULL",
 877                            (int) len);
 878                 return;
 879         }
 880
 881         lm_exch = *pos;
 882         pos++;            /* skip over the bits and the exch */
 883         len--;
 884
 885         /*
 886          * if we're fragmenting then this should be an ACK with no data,
 887          * just return and continue fragmenting in the "build" section above
 888          */
 889         if (data->out_frag_pos) {
 890                 if (len > 1)
 891                         wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
 892                                    "Fragmenting but not an ACK");
 893                 else
 894                         wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
 895                                    "peer");
 896                 return;
 897         }
 898         /*
 899          * if we're receiving fragmented packets then we need to buffer...
 900          *
 901          * the first fragment has a total length
 902          */
 903         if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
 904                 tot_len = WPA_GET_BE16(pos);
 905                 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
 906                            "length = %d", tot_len);
 907                 if (tot_len > 15000)
 908                         return;
 909                 data->inbuf = wpabuf_alloc(tot_len);
 910                 if (data->inbuf == NULL) {
 911                         wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
 912                                    "buffer fragments!");
 913                         return;
 914                 }
 915                 pos += sizeof(u16);
 916                 len -= sizeof(u16);
 917         }
 918         /*
 919          * the first and all intermediate fragments have the M bit set
 920          */
 921         if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
 922                 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
 923                         wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
 924                                    "attack detected! (%d+%d > %d)",
 925                                    (int) data->in_frag_pos, (int) len,
 926                                    (int) wpabuf_size(data->inbuf));
 927                         eap_pwd_state(data, FAILURE);
 928                         return;
 929                 }
 930                 wpabuf_put_data(data->inbuf, pos, len);
 931                 data->in_frag_pos += len;
 932                 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
 933                            (int) len);
 934                 return;
 935         }
 936         /*
 937          * last fragment won't have the M bit set (but we're obviously
 938          * buffering fragments so that's how we know it's the last)
 939          */
 940         if (data->in_frag_pos) {
 941                 wpabuf_put_data(data->inbuf, pos, len);
 942                 data->in_frag_pos += len;
 943                 pos = wpabuf_head_u8(data->inbuf);
 944                 len = data->in_frag_pos;
 945                 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
 946                            (int) len);
 947         }
 948         switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
 949         case EAP_PWD_OPCODE_ID_EXCH:
 950                 eap_pwd_process_id_resp(sm, data, pos, len);
 951                 break;
 952         case EAP_PWD_OPCODE_COMMIT_EXCH:
 953                 eap_pwd_process_commit_resp(sm, data, pos, len);
 954                 break;
 955         case EAP_PWD_OPCODE_CONFIRM_EXCH:
 956                 eap_pwd_process_confirm_resp(sm, data, pos, len);
 957                 break;
 958         }
 959         /*
 960          * if we had been buffering fragments, here's a great place
 961          * to clean up
 962          */
 963         if (data->in_frag_pos) {
 964                 wpabuf_free(data->inbuf);
 965                 data->inbuf = NULL;
 966                 data->in_frag_pos = 0;
 967         }
 968 }
 969
 970
 971 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
 972 {
 973         struct eap_pwd_data *data = priv;
 974         u8 *key;
 975
 976         if (data->state != SUCCESS)
 977                 return NULL;
 978
 979         key = os_malloc(EAP_MSK_LEN);
 980         if (key == NULL)
 981                 return NULL;
 982
 983         os_memcpy(key, data->msk, EAP_MSK_LEN);
 984         *len = EAP_MSK_LEN;
 985
 986         return key;
 987 }
 988
 989
 990 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 991 {
 992         struct eap_pwd_data *data = priv;
 993         u8 *key;
 994
 995         if (data->state != SUCCESS)
 996                 return NULL;
 997
 998         key = os_malloc(EAP_EMSK_LEN);
 999         if (key == NULL)
1000                 return NULL;
1001
1002         os_memcpy(key, data->emsk, EAP_EMSK_LEN);
1003         *len = EAP_EMSK_LEN;
1004
1005         return key;
1006 }
1007
1008
1009 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
1010 {
1011         struct eap_pwd_data *data = priv;
1012         return data->state == SUCCESS;
1013 }
1014
1015
1016 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1017 {
1018         struct eap_pwd_data *data = priv;
1019         return (data->state == SUCCESS) || (data->state == FAILURE);
1020 }
1021
1022
1023 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
1024 {
1025         struct eap_pwd_data *data = priv;
1026         u8 *id;
1027
1028         if (data->state != SUCCESS)
1029                 return NULL;
1030
1031         id = os_malloc(1 + SHA256_MAC_LEN);
1032         if (id == NULL)
1033                 return NULL;
1034
1035         os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
1036         *len = 1 + SHA256_MAC_LEN;
1037
1038         return id;
1039 }
1040
1041
1042 int eap_server_pwd_register(void)
1043 {
1044         struct eap_method *eap;
1045         int ret;
1046         struct timeval tp;
1047         struct timezone tz;
1048         u32 sr;
1049
1050         sr = 0xdeaddada;
1051         (void) gettimeofday(&tp, &tz);
1052         sr ^= (tp.tv_sec ^ tp.tv_usec);
1053         srandom(sr);
1054
1055         eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1056                                       EAP_VENDOR_IETF, EAP_TYPE_PWD,
1057                                       "PWD");
1058         if (eap == NULL)
1059                 return -1;
1060
1061         eap->init = eap_pwd_init;
1062         eap->reset = eap_pwd_reset;
1063         eap->buildReq = eap_pwd_build_req;
1064         eap->check = eap_pwd_check;
1065         eap->process = eap_pwd_process;
1066         eap->isDone = eap_pwd_is_done;
1067         eap->getKey = eap_pwd_getkey;
1068         eap->get_emsk = eap_pwd_get_emsk;
1069         eap->isSuccess = eap_pwd_is_success;
1070         eap->getSessionId = eap_pwd_get_session_id;
1071
1072         ret = eap_server_method_register(eap);
1073         if (ret)
1074                 eap_server_method_free(eap);
1075         return ret;
1076 }
1077