libeap/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 "crypto/ms_funcs.h"
  14 #include "eap_server/eap_i.h"
  15 #include "eap_common/eap_pwd_common.h"
  16
  17
  18 struct eap_pwd_data {
  19         enum {
  20                 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE
  21         } state;
  22         u8 *id_peer;
  23         size_t id_peer_len;
  24         u8 *id_server;
  25         size_t id_server_len;
  26         u8 *password;
  27         size_t password_len;
  28         int password_hash;
  29         u32 token;
  30         u16 group_num;
  31         EAP_PWD_group *grp;
  32
  33         struct wpabuf *inbuf;
  34         size_t in_frag_pos;
  35         struct wpabuf *outbuf;
  36         size_t out_frag_pos;
  37         size_t mtu;
  38
  39         BIGNUM *k;
  40         BIGNUM *private_value;
  41         BIGNUM *peer_scalar;
  42         BIGNUM *my_scalar;
  43         EC_POINT *my_element;
  44         EC_POINT *peer_element;
  45
  46         u8 my_confirm[SHA256_MAC_LEN];
  47
  48         u8 msk[EAP_MSK_LEN];
  49         u8 emsk[EAP_EMSK_LEN];
  50         u8 session_id[1 + SHA256_MAC_LEN];
  51
  52         BN_CTX *bnctx;
  53 };
  54
  55
  56 static const char * eap_pwd_state_txt(int state)
  57 {
  58         switch (state) {
  59         case PWD_ID_Req:
  60                 return "PWD-ID-Req";
  61         case PWD_Commit_Req:
  62                 return "PWD-Commit-Req";
  63         case PWD_Confirm_Req:
  64                 return "PWD-Confirm-Req";
  65         case SUCCESS:
  66                 return "SUCCESS";
  67         case FAILURE:
  68                 return "FAILURE";
  69         default:
  70                 return "PWD-Unk";
  71         }
  72 }
  73
  74
  75 static void eap_pwd_state(struct eap_pwd_data *data, int state)
  76 {
  77         wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s",
  78                    eap_pwd_state_txt(data->state), eap_pwd_state_txt(state));
  79         data->state = state;
  80 }
  81
  82
  83 static void * eap_pwd_init(struct eap_sm *sm)
  84 {
  85         struct eap_pwd_data *data;
  86
  87         if (sm->user == NULL || sm->user->password == NULL ||
  88             sm->user->password_len == 0) {
  89                 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not "
  90                            "configured");
  91                 return NULL;
  92         }
  93
  94         data = os_zalloc(sizeof(*data));
  95         if (data == NULL)
  96                 return NULL;
  97
  98         data->group_num = sm->pwd_group;
  99         wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d",
 100                    data->group_num);
 101         data->state = PWD_ID_Req;
 102
 103         data->id_server = (u8 *) os_strdup("server");
 104         if (data->id_server)
 105                 data->id_server_len = os_strlen((char *) data->id_server);
 106
 107         data->password = os_malloc(sm->user->password_len);
 108         if (data->password == NULL) {
 109                 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password "
 110                            "fail");
 111                 bin_clear_free(data->id_server, data->id_server_len);
 112                 os_free(data);
 113                 return NULL;
 114         }
 115         data->password_len = sm->user->password_len;
 116         os_memcpy(data->password, sm->user->password, data->password_len);
 117         data->password_hash = sm->user->password_hash;
 118
 119         data->bnctx = BN_CTX_new();
 120         if (data->bnctx == NULL) {
 121                 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail");
 122                 bin_clear_free(data->password, data->password_len);
 123                 bin_clear_free(data->id_server, data->id_server_len);
 124                 os_free(data);
 125                 return NULL;
 126         }
 127
 128         data->in_frag_pos = data->out_frag_pos = 0;
 129         data->inbuf = data->outbuf = NULL;
 130         /* use default MTU from RFC 5931 if not configured otherwise */
 131         data->mtu = sm->fragment_size > 0 ? sm->fragment_size : 1020;
 132
 133         return data;
 134 }
 135
 136
 137 static void eap_pwd_reset(struct eap_sm *sm, void *priv)
 138 {
 139         struct eap_pwd_data *data = priv;
 140
 141         BN_clear_free(data->private_value);
 142         BN_clear_free(data->peer_scalar);
 143         BN_clear_free(data->my_scalar);
 144         BN_clear_free(data->k);
 145         BN_CTX_free(data->bnctx);
 146         EC_POINT_clear_free(data->my_element);
 147         EC_POINT_clear_free(data->peer_element);
 148         bin_clear_free(data->id_peer, data->id_peer_len);
 149         bin_clear_free(data->id_server, data->id_server_len);
 150         bin_clear_free(data->password, data->password_len);
 151         if (data->grp) {
 152                 EC_GROUP_free(data->grp->group);
 153                 EC_POINT_clear_free(data->grp->pwe);
 154                 BN_clear_free(data->grp->order);
 155                 BN_clear_free(data->grp->prime);
 156                 os_free(data->grp);
 157         }
 158         wpabuf_free(data->inbuf);
 159         wpabuf_free(data->outbuf);
 160         bin_clear_free(data, sizeof(*data));
 161 }
 162
 163
 164 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data,
 165                                  u8 id)
 166 {
 167         wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request");
 168         /*
 169          * if we're fragmenting then we already have an id request, just return
 170          */
 171         if (data->out_frag_pos)
 172                 return;
 173
 174         data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) +
 175                                     data->id_server_len);
 176         if (data->outbuf == NULL) {
 177                 eap_pwd_state(data, FAILURE);
 178                 return;
 179         }
 180
 181         /* an lfsr is good enough to generate unpredictable tokens */
 182         data->token = os_random();
 183         wpabuf_put_be16(data->outbuf, data->group_num);
 184         wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC);
 185         wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF);
 186         wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token));
 187         wpabuf_put_u8(data->outbuf, data->password_hash ? EAP_PWD_PREP_MS :
 188                       EAP_PWD_PREP_NONE);
 189         wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len);
 190 }
 191
 192
 193 static void eap_pwd_build_commit_req(struct eap_sm *sm,
 194                                      struct eap_pwd_data *data, u8 id)
 195 {
 196         BIGNUM *mask = NULL, *x = NULL, *y = NULL;
 197         u8 *scalar = NULL, *element = NULL;
 198         u16 offset;
 199
 200         wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request");
 201         /*
 202          * if we're fragmenting then we already have an commit request, just
 203          * return
 204          */
 205         if (data->out_frag_pos)
 206                 return;
 207
 208         if (((data->private_value = BN_new()) == NULL) ||
 209             ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) ||
 210             ((data->my_scalar = BN_new()) == NULL) ||
 211             ((mask = BN_new()) == NULL)) {
 212                 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation "
 213                            "fail");
 214                 goto fin;
 215         }
 216
 217         if (BN_rand_range(data->private_value, data->grp->order) != 1 ||
 218             BN_rand_range(mask, data->grp->order) != 1 ||
 219             BN_add(data->my_scalar, data->private_value, mask) != 1 ||
 220             BN_mod(data->my_scalar, data->my_scalar, data->grp->order,
 221                    data->bnctx) != 1) {
 222                 wpa_printf(MSG_INFO,
 223                            "EAP-pwd (server): unable to get randomness");
 224                 goto fin;
 225         }
 226
 227         if (!EC_POINT_mul(data->grp->group, data->my_element, NULL,
 228                           data->grp->pwe, mask, data->bnctx)) {
 229                 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation "
 230                            "fail");
 231                 eap_pwd_state(data, FAILURE);
 232                 goto fin;
 233         }
 234
 235         if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx))
 236         {
 237                 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion "
 238                            "fail");
 239                 goto fin;
 240         }
 241         BN_clear_free(mask);
 242
 243         if (((x = BN_new()) == NULL) ||
 244             ((y = BN_new()) == NULL)) {
 245                 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation "
 246                            "fail");
 247                 goto fin;
 248         }
 249         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 250                                                  data->my_element, x, y,
 251                                                  data->bnctx)) {
 252                 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment "
 253                            "fail");
 254                 goto fin;
 255         }
 256
 257         if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) ||
 258             ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) ==
 259              NULL)) {
 260                 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail");
 261                 goto fin;
 262         }
 263
 264         /*
 265          * bignums occupy as little memory as possible so one that is
 266          * sufficiently smaller than the prime or order might need pre-pending
 267          * with zeros.
 268          */
 269         os_memset(scalar, 0, BN_num_bytes(data->grp->order));
 270         os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2);
 271         offset = BN_num_bytes(data->grp->order) -
 272                 BN_num_bytes(data->my_scalar);
 273         BN_bn2bin(data->my_scalar, scalar + offset);
 274
 275         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 276         BN_bn2bin(x, element + offset);
 277         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 278         BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset);
 279
 280         data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) +
 281                                     BN_num_bytes(data->grp->order));
 282         if (data->outbuf == NULL)
 283                 goto fin;
 284
 285         /* We send the element as (x,y) followed by the scalar */
 286         wpabuf_put_data(data->outbuf, element,
 287                         2 * BN_num_bytes(data->grp->prime));
 288         wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order));
 289
 290 fin:
 291         os_free(scalar);
 292         os_free(element);
 293         BN_clear_free(x);
 294         BN_clear_free(y);
 295         if (data->outbuf == NULL)
 296                 eap_pwd_state(data, FAILURE);
 297 }
 298
 299
 300 static void eap_pwd_build_confirm_req(struct eap_sm *sm,
 301                                       struct eap_pwd_data *data, u8 id)
 302 {
 303         BIGNUM *x = NULL, *y = NULL;
 304         struct crypto_hash *hash;
 305         u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
 306         u16 grp;
 307         int offset;
 308
 309         wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request");
 310         /*
 311          * if we're fragmenting then we already have an confirm request, just
 312          * return
 313          */
 314         if (data->out_frag_pos)
 315                 return;
 316
 317         /* Each component of the cruft will be at most as big as the prime */
 318         if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
 319             ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
 320                 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation "
 321                            "fail");
 322                 goto fin;
 323         }
 324
 325         /*
 326          * commit is H(k | server_element | server_scalar | peer_element |
 327          *             peer_scalar | ciphersuite)
 328          */
 329         hash = eap_pwd_h_init();
 330         if (hash == NULL)
 331                 goto fin;
 332
 333         /*
 334          * Zero the memory each time because this is mod prime math and some
 335          * value may start with a few zeros and the previous one did not.
 336          *
 337          * First is k
 338          */
 339         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 340         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
 341         BN_bn2bin(data->k, cruft + offset);
 342         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 343
 344         /* server element: x, y */
 345         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 346                                                  data->my_element, x, y,
 347                                                  data->bnctx)) {
 348                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 349                            "assignment fail");
 350                 goto fin;
 351         }
 352
 353         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 354         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 355         BN_bn2bin(x, cruft + offset);
 356         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 357         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 358         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 359         BN_bn2bin(y, cruft + offset);
 360         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 361
 362         /* server scalar */
 363         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 364         offset = BN_num_bytes(data->grp->order) -
 365                 BN_num_bytes(data->my_scalar);
 366         BN_bn2bin(data->my_scalar, cruft + offset);
 367         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 368
 369         /* peer element: x, y */
 370         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 371                                                  data->peer_element, x, y,
 372                                                  data->bnctx)) {
 373                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 374                            "assignment fail");
 375                 goto fin;
 376         }
 377
 378         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 379         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 380         BN_bn2bin(x, cruft + offset);
 381         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 382         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 383         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 384         BN_bn2bin(y, cruft + offset);
 385         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 386
 387         /* peer scalar */
 388         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 389         offset = BN_num_bytes(data->grp->order) -
 390                 BN_num_bytes(data->peer_scalar);
 391         BN_bn2bin(data->peer_scalar, cruft + offset);
 392         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 393
 394         /* ciphersuite */
 395         grp = htons(data->group_num);
 396         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 397         ptr = cruft;
 398         os_memcpy(ptr, &grp, sizeof(u16));
 399         ptr += sizeof(u16);
 400         *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
 401         ptr += sizeof(u8);
 402         *ptr = EAP_PWD_DEFAULT_PRF;
 403         ptr += sizeof(u8);
 404         eap_pwd_h_update(hash, cruft, ptr - cruft);
 405
 406         /* all done with the random function */
 407         eap_pwd_h_final(hash, conf);
 408         os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN);
 409
 410         data->outbuf = wpabuf_alloc(SHA256_MAC_LEN);
 411         if (data->outbuf == NULL)
 412                 goto fin;
 413
 414         wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN);
 415
 416 fin:
 417         bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
 418         BN_clear_free(x);
 419         BN_clear_free(y);
 420         if (data->outbuf == NULL)
 421                 eap_pwd_state(data, FAILURE);
 422 }
 423
 424
 425 static struct wpabuf *
 426 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id)
 427 {
 428         struct eap_pwd_data *data = priv;
 429         struct wpabuf *req;
 430         u8 lm_exch;
 431         const u8 *buf;
 432         u16 totlen = 0;
 433         size_t len;
 434
 435         /*
 436          * if we're buffering response fragments then just ACK
 437          */
 438         if (data->in_frag_pos) {
 439                 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!");
 440                 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
 441                                     EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id);
 442                 if (req == NULL) {
 443                         eap_pwd_state(data, FAILURE);
 444                         return NULL;
 445                 }
 446                 switch (data->state) {
 447                 case PWD_ID_Req:
 448                         wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH);
 449                         break;
 450                 case PWD_Commit_Req:
 451                         wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH);
 452                         break;
 453                 case PWD_Confirm_Req:
 454                         wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH);
 455                         break;
 456                 default:
 457                         eap_pwd_state(data, FAILURE);   /* just to be sure */
 458                         wpabuf_free(req);
 459                         return NULL;
 460                 }
 461                 return req;
 462         }
 463
 464         /*
 465          * build the data portion of a request
 466          */
 467         switch (data->state) {
 468         case PWD_ID_Req:
 469                 eap_pwd_build_id_req(sm, data, id);
 470                 lm_exch = EAP_PWD_OPCODE_ID_EXCH;
 471                 break;
 472         case PWD_Commit_Req:
 473                 eap_pwd_build_commit_req(sm, data, id);
 474                 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH;
 475                 break;
 476         case PWD_Confirm_Req:
 477                 eap_pwd_build_confirm_req(sm, data, id);
 478                 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH;
 479                 break;
 480         default:
 481                 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req",
 482                            data->state);
 483                 eap_pwd_state(data, FAILURE);
 484                 lm_exch = 0;    /* hush now, sweet compiler */
 485                 break;
 486         }
 487
 488         if (data->state == FAILURE)
 489                 return NULL;
 490
 491         /*
 492          * determine whether that data needs to be fragmented
 493          */
 494         len = wpabuf_len(data->outbuf) - data->out_frag_pos;
 495         if ((len + EAP_PWD_HDR_SIZE) > data->mtu) {
 496                 len = data->mtu - EAP_PWD_HDR_SIZE;
 497                 EAP_PWD_SET_MORE_BIT(lm_exch);
 498                 /*
 499                  * if this is the first fragment, need to set the M bit
 500                  * and add the total length to the eap_pwd_hdr
 501                  */
 502                 if (data->out_frag_pos == 0) {
 503                         EAP_PWD_SET_LENGTH_BIT(lm_exch);
 504                         totlen = wpabuf_len(data->outbuf) +
 505                                 EAP_PWD_HDR_SIZE + sizeof(u16);
 506                         len -= sizeof(u16);
 507                         wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, "
 508                                    "total length = %d", totlen);
 509                 }
 510                 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment",
 511                            (int) len);
 512         }
 513
 514         /*
 515          * alloc an eap request and populate it with the data
 516          */
 517         req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD,
 518                             EAP_PWD_HDR_SIZE + len +
 519                             (totlen ? sizeof(u16) : 0),
 520                             EAP_CODE_REQUEST, id);
 521         if (req == NULL) {
 522                 eap_pwd_state(data, FAILURE);
 523                 return NULL;
 524         }
 525
 526         wpabuf_put_u8(req, lm_exch);
 527         if (EAP_PWD_GET_LENGTH_BIT(lm_exch))
 528                 wpabuf_put_be16(req, totlen);
 529
 530         buf = wpabuf_head_u8(data->outbuf);
 531         wpabuf_put_data(req, buf + data->out_frag_pos, len);
 532         data->out_frag_pos += len;
 533         /*
 534          * either not fragged or last fragment, either way free up the data
 535          */
 536         if (data->out_frag_pos >= wpabuf_len(data->outbuf)) {
 537                 wpabuf_free(data->outbuf);
 538                 data->outbuf = NULL;
 539                 data->out_frag_pos = 0;
 540         }
 541
 542         return req;
 543 }
 544
 545
 546 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv,
 547                              struct wpabuf *respData)
 548 {
 549         struct eap_pwd_data *data = priv;
 550         const u8 *pos;
 551         size_t len;
 552
 553         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
 554         if (pos == NULL || len < 1) {
 555                 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame");
 556                 return TRUE;
 557         }
 558
 559         wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d",
 560                    EAP_PWD_GET_EXCHANGE(*pos), (int) len);
 561
 562         if (data->state == PWD_ID_Req &&
 563             ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH))
 564                 return FALSE;
 565
 566         if (data->state == PWD_Commit_Req &&
 567             ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH))
 568                 return FALSE;
 569
 570         if (data->state == PWD_Confirm_Req &&
 571             ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH))
 572                 return FALSE;
 573
 574         wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d",
 575                    *pos, data->state);
 576
 577         return TRUE;
 578 }
 579
 580
 581 static void eap_pwd_process_id_resp(struct eap_sm *sm,
 582                                     struct eap_pwd_data *data,
 583                                     const u8 *payload, size_t payload_len)
 584 {
 585         struct eap_pwd_id *id;
 586         const u8 *password;
 587         size_t password_len;
 588         u8 pwhashhash[16];
 589         int res;
 590
 591         if (payload_len < sizeof(struct eap_pwd_id)) {
 592                 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response");
 593                 return;
 594         }
 595
 596         id = (struct eap_pwd_id *) payload;
 597         if ((data->group_num != be_to_host16(id->group_num)) ||
 598             (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) ||
 599             (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) ||
 600             (id->prf != EAP_PWD_DEFAULT_PRF)) {
 601                 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters");
 602                 eap_pwd_state(data, FAILURE);
 603                 return;
 604         }
 605         data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id));
 606         if (data->id_peer == NULL) {
 607                 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail");
 608                 return;
 609         }
 610         data->id_peer_len = payload_len - sizeof(struct eap_pwd_id);
 611         os_memcpy(data->id_peer, id->identity, data->id_peer_len);
 612         wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of",
 613                           data->id_peer, data->id_peer_len);
 614
 615         data->grp = os_zalloc(sizeof(EAP_PWD_group));
 616         if (data->grp == NULL) {
 617                 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for "
 618                            "group");
 619                 return;
 620         }
 621
 622         if (data->password_hash) {
 623                 res = hash_nt_password_hash(data->password, pwhashhash);
 624                 if (res)
 625                         return;
 626                 password = pwhashhash;
 627                 password_len = sizeof(pwhashhash);
 628         } else {
 629                 password = data->password;
 630                 password_len = data->password_len;
 631         }
 632
 633         res = compute_password_element(data->grp, data->group_num,
 634                                        password, password_len,
 635                                        data->id_server, data->id_server_len,
 636                                        data->id_peer, data->id_peer_len,
 637                                        (u8 *) &data->token);
 638         os_memset(pwhashhash, 0, sizeof(pwhashhash));
 639         if (res) {
 640                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute "
 641                            "PWE");
 642                 return;
 643         }
 644         wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...",
 645                    BN_num_bits(data->grp->prime));
 646
 647         eap_pwd_state(data, PWD_Commit_Req);
 648 }
 649
 650
 651 static void
 652 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 653                             const u8 *payload, size_t payload_len)
 654 {
 655         u8 *ptr;
 656         BIGNUM *x = NULL, *y = NULL, *cofactor = NULL;
 657         EC_POINT *K = NULL, *point = NULL;
 658         int res = 0;
 659         size_t prime_len, order_len;
 660
 661         wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response");
 662
 663         prime_len = BN_num_bytes(data->grp->prime);
 664         order_len = BN_num_bytes(data->grp->order);
 665
 666         if (payload_len != 2 * prime_len + order_len) {
 667                 wpa_printf(MSG_INFO,
 668                            "EAP-pwd: Unexpected Commit payload length %u (expected %u)",
 669                            (unsigned int) payload_len,
 670                            (unsigned int) (2 * prime_len + order_len));
 671                 goto fin;
 672         }
 673
 674         if (((data->peer_scalar = BN_new()) == NULL) ||
 675             ((data->k = BN_new()) == NULL) ||
 676             ((cofactor = BN_new()) == NULL) ||
 677             ((x = BN_new()) == NULL) ||
 678             ((y = BN_new()) == NULL) ||
 679             ((point = EC_POINT_new(data->grp->group)) == NULL) ||
 680             ((K = EC_POINT_new(data->grp->group)) == NULL) ||
 681             ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) {
 682                 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation "
 683                            "fail");
 684                 goto fin;
 685         }
 686
 687         if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) {
 688                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get "
 689                            "cofactor for curve");
 690                 goto fin;
 691         }
 692
 693         /* element, x then y, followed by scalar */
 694         ptr = (u8 *) payload;
 695         BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x);
 696         ptr += BN_num_bytes(data->grp->prime);
 697         BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y);
 698         ptr += BN_num_bytes(data->grp->prime);
 699         BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar);
 700         if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group,
 701                                                  data->peer_element, x, y,
 702                                                  data->bnctx)) {
 703                 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element "
 704                            "fail");
 705                 goto fin;
 706         }
 707
 708         /* check to ensure peer's element is not in a small sub-group */
 709         if (BN_cmp(cofactor, BN_value_one())) {
 710                 if (!EC_POINT_mul(data->grp->group, point, NULL,
 711                                   data->peer_element, cofactor, NULL)) {
 712                         wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
 713                                    "multiply peer element by order");
 714                         goto fin;
 715                 }
 716                 if (EC_POINT_is_at_infinity(data->grp->group, point)) {
 717                         wpa_printf(MSG_INFO, "EAP-PWD (server): peer element "
 718                                    "is at infinity!\n");
 719                         goto fin;
 720                 }
 721         }
 722
 723         /* compute the shared key, k */
 724         if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe,
 725                            data->peer_scalar, data->bnctx)) ||
 726             (!EC_POINT_add(data->grp->group, K, K, data->peer_element,
 727                            data->bnctx)) ||
 728             (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value,
 729                            data->bnctx))) {
 730                 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key "
 731                            "fail");
 732                 goto fin;
 733         }
 734
 735         /* ensure that the shared key isn't in a small sub-group */
 736         if (BN_cmp(cofactor, BN_value_one())) {
 737                 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor,
 738                                   NULL)) {
 739                         wpa_printf(MSG_INFO, "EAP-PWD (server): cannot "
 740                                    "multiply shared key point by order!\n");
 741                         goto fin;
 742                 }
 743         }
 744
 745         /*
 746          * This check is strictly speaking just for the case above where
 747          * co-factor > 1 but it was suggested that even though this is probably
 748          * never going to happen it is a simple and safe check "just to be
 749          * sure" so let's be safe.
 750          */
 751         if (EC_POINT_is_at_infinity(data->grp->group, K)) {
 752                 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is "
 753                            "at infinity");
 754                 goto fin;
 755         }
 756         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k,
 757                                                  NULL, data->bnctx)) {
 758                 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract "
 759                            "shared secret from secret point");
 760                 goto fin;
 761         }
 762         res = 1;
 763
 764 fin:
 765         EC_POINT_clear_free(K);
 766         EC_POINT_clear_free(point);
 767         BN_clear_free(cofactor);
 768         BN_clear_free(x);
 769         BN_clear_free(y);
 770
 771         if (res)
 772                 eap_pwd_state(data, PWD_Confirm_Req);
 773         else
 774                 eap_pwd_state(data, FAILURE);
 775 }
 776
 777
 778 static void
 779 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data,
 780                              const u8 *payload, size_t payload_len)
 781 {
 782         BIGNUM *x = NULL, *y = NULL;
 783         struct crypto_hash *hash;
 784         u32 cs;
 785         u16 grp;
 786         u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr;
 787         int offset;
 788
 789         if (payload_len != SHA256_MAC_LEN) {
 790                 wpa_printf(MSG_INFO,
 791                            "EAP-pwd: Unexpected Confirm payload length %u (expected %u)",
 792                            (unsigned int) payload_len, SHA256_MAC_LEN);
 793                 goto fin;
 794         }
 795
 796         /* build up the ciphersuite: group | random_function | prf */
 797         grp = htons(data->group_num);
 798         ptr = (u8 *) &cs;
 799         os_memcpy(ptr, &grp, sizeof(u16));
 800         ptr += sizeof(u16);
 801         *ptr = EAP_PWD_DEFAULT_RAND_FUNC;
 802         ptr += sizeof(u8);
 803         *ptr = EAP_PWD_DEFAULT_PRF;
 804
 805         /* each component of the cruft will be at most as big as the prime */
 806         if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) ||
 807             ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) {
 808                 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail");
 809                 goto fin;
 810         }
 811
 812         /*
 813          * commit is H(k | peer_element | peer_scalar | server_element |
 814          *             server_scalar | ciphersuite)
 815          */
 816         hash = eap_pwd_h_init();
 817         if (hash == NULL)
 818                 goto fin;
 819
 820         /* k */
 821         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 822         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k);
 823         BN_bn2bin(data->k, cruft + offset);
 824         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 825
 826         /* peer element: x, y */
 827         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 828                                                  data->peer_element, x, y,
 829                                                  data->bnctx)) {
 830                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 831                            "assignment fail");
 832                 goto fin;
 833         }
 834         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 835         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 836         BN_bn2bin(x, cruft + offset);
 837         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 838         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 839         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 840         BN_bn2bin(y, cruft + offset);
 841         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 842
 843         /* peer scalar */
 844         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 845         offset = BN_num_bytes(data->grp->order) -
 846                 BN_num_bytes(data->peer_scalar);
 847         BN_bn2bin(data->peer_scalar, cruft + offset);
 848         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 849
 850         /* server element: x, y */
 851         if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group,
 852                                                  data->my_element, x, y,
 853                                                  data->bnctx)) {
 854                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point "
 855                            "assignment fail");
 856                 goto fin;
 857         }
 858
 859         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 860         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x);
 861         BN_bn2bin(x, cruft + offset);
 862         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 863         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 864         offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y);
 865         BN_bn2bin(y, cruft + offset);
 866         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime));
 867
 868         /* server scalar */
 869         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 870         offset = BN_num_bytes(data->grp->order) -
 871                 BN_num_bytes(data->my_scalar);
 872         BN_bn2bin(data->my_scalar, cruft + offset);
 873         eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order));
 874
 875         /* ciphersuite */
 876         os_memset(cruft, 0, BN_num_bytes(data->grp->prime));
 877         eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32));
 878
 879         /* all done */
 880         eap_pwd_h_final(hash, conf);
 881
 882         ptr = (u8 *) payload;
 883         if (os_memcmp_const(conf, ptr, SHA256_MAC_LEN)) {
 884                 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not "
 885                            "verify");
 886                 goto fin;
 887         }
 888
 889         wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified");
 890         if (compute_keys(data->grp, data->bnctx, data->k,
 891                          data->peer_scalar, data->my_scalar, conf,
 892                          data->my_confirm, &cs, data->msk, data->emsk,
 893                          data->session_id) < 0)
 894                 eap_pwd_state(data, FAILURE);
 895         else
 896                 eap_pwd_state(data, SUCCESS);
 897
 898 fin:
 899         bin_clear_free(cruft, BN_num_bytes(data->grp->prime));
 900         BN_clear_free(x);
 901         BN_clear_free(y);
 902 }
 903
 904
 905 static void eap_pwd_process(struct eap_sm *sm, void *priv,
 906                             struct wpabuf *respData)
 907 {
 908         struct eap_pwd_data *data = priv;
 909         const u8 *pos;
 910         size_t len;
 911         u8 lm_exch;
 912         u16 tot_len;
 913
 914         pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len);
 915         if ((pos == NULL) || (len < 1)) {
 916                 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d",
 917                            (pos == NULL) ? "is NULL" : "is not NULL",
 918                            (int) len);
 919                 return;
 920         }
 921
 922         lm_exch = *pos;
 923         pos++;            /* skip over the bits and the exch */
 924         len--;
 925
 926         /*
 927          * if we're fragmenting then this should be an ACK with no data,
 928          * just return and continue fragmenting in the "build" section above
 929          */
 930         if (data->out_frag_pos) {
 931                 if (len > 1)
 932                         wpa_printf(MSG_INFO, "EAP-pwd: Bad response! "
 933                                    "Fragmenting but not an ACK");
 934                 else
 935                         wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from "
 936                                    "peer");
 937                 return;
 938         }
 939         /*
 940          * if we're receiving fragmented packets then we need to buffer...
 941          *
 942          * the first fragment has a total length
 943          */
 944         if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) {
 945                 if (len < 2) {
 946                         wpa_printf(MSG_DEBUG,
 947                                    "EAP-pwd: Frame too short to contain Total-Length field");
 948                         return;
 949                 }
 950                 tot_len = WPA_GET_BE16(pos);
 951                 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total "
 952                            "length = %d", tot_len);
 953                 if (tot_len > 15000)
 954                         return;
 955                 if (data->inbuf) {
 956                         wpa_printf(MSG_DEBUG,
 957                                    "EAP-pwd: Unexpected new fragment start when previous fragment is still in use");
 958                         return;
 959                 }
 960                 data->inbuf = wpabuf_alloc(tot_len);
 961                 if (data->inbuf == NULL) {
 962                         wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to "
 963                                    "buffer fragments!");
 964                         return;
 965                 }
 966                 data->in_frag_pos = 0;
 967                 pos += sizeof(u16);
 968                 len -= sizeof(u16);
 969         }
 970         /*
 971          * the first and all intermediate fragments have the M bit set
 972          */
 973         if (EAP_PWD_GET_MORE_BIT(lm_exch)) {
 974                 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) {
 975                         wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow "
 976                                    "attack detected! (%d+%d > %d)",
 977                                    (int) data->in_frag_pos, (int) len,
 978                                    (int) wpabuf_size(data->inbuf));
 979                         eap_pwd_state(data, FAILURE);
 980                         return;
 981                 }
 982                 wpabuf_put_data(data->inbuf, pos, len);
 983                 data->in_frag_pos += len;
 984                 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment",
 985                            (int) len);
 986                 return;
 987         }
 988         /*
 989          * last fragment won't have the M bit set (but we're obviously
 990          * buffering fragments so that's how we know it's the last)
 991          */
 992         if (data->in_frag_pos) {
 993                 wpabuf_put_data(data->inbuf, pos, len);
 994                 data->in_frag_pos += len;
 995                 pos = wpabuf_head_u8(data->inbuf);
 996                 len = data->in_frag_pos;
 997                 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes",
 998                            (int) len);
 999         }
1000         switch (EAP_PWD_GET_EXCHANGE(lm_exch)) {
1001         case EAP_PWD_OPCODE_ID_EXCH:
1002                 eap_pwd_process_id_resp(sm, data, pos, len);
1003                 break;
1004         case EAP_PWD_OPCODE_COMMIT_EXCH:
1005                 eap_pwd_process_commit_resp(sm, data, pos, len);
1006                 break;
1007         case EAP_PWD_OPCODE_CONFIRM_EXCH:
1008                 eap_pwd_process_confirm_resp(sm, data, pos, len);
1009                 break;
1010         }
1011         /*
1012          * if we had been buffering fragments, here's a great place
1013          * to clean up
1014          */
1015         if (data->in_frag_pos) {
1016                 wpabuf_free(data->inbuf);
1017                 data->inbuf = NULL;
1018                 data->in_frag_pos = 0;
1019         }
1020 }
1021
1022
1023 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len)
1024 {
1025         struct eap_pwd_data *data = priv;
1026         u8 *key;
1027
1028         if (data->state != SUCCESS)
1029                 return NULL;
1030
1031         key = os_malloc(EAP_MSK_LEN);
1032         if (key == NULL)
1033                 return NULL;
1034
1035         os_memcpy(key, data->msk, EAP_MSK_LEN);
1036         *len = EAP_MSK_LEN;
1037
1038         return key;
1039 }
1040
1041
1042 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
1043 {
1044         struct eap_pwd_data *data = priv;
1045         u8 *key;
1046
1047         if (data->state != SUCCESS)
1048                 return NULL;
1049
1050         key = os_malloc(EAP_EMSK_LEN);
1051         if (key == NULL)
1052                 return NULL;
1053
1054         os_memcpy(key, data->emsk, EAP_EMSK_LEN);
1055         *len = EAP_EMSK_LEN;
1056
1057         return key;
1058 }
1059
1060
1061 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv)
1062 {
1063         struct eap_pwd_data *data = priv;
1064         return data->state == SUCCESS;
1065 }
1066
1067
1068 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv)
1069 {
1070         struct eap_pwd_data *data = priv;
1071         return (data->state == SUCCESS) || (data->state == FAILURE);
1072 }
1073
1074
1075 static u8 * eap_pwd_get_session_id(struct eap_sm *sm, void *priv, size_t *len)
1076 {
1077         struct eap_pwd_data *data = priv;
1078         u8 *id;
1079
1080         if (data->state != SUCCESS)
1081                 return NULL;
1082
1083         id = os_malloc(1 + SHA256_MAC_LEN);
1084         if (id == NULL)
1085                 return NULL;
1086
1087         os_memcpy(id, data->session_id, 1 + SHA256_MAC_LEN);
1088         *len = 1 + SHA256_MAC_LEN;
1089
1090         return id;
1091 }
1092
1093
1094 int eap_server_pwd_register(void)
1095 {
1096         struct eap_method *eap;
1097         int ret;
1098         struct timeval tp;
1099         struct timezone tz;
1100         u32 sr;
1101
1102         sr = 0xdeaddada;
1103         (void) gettimeofday(&tp, &tz);
1104         sr ^= (tp.tv_sec ^ tp.tv_usec);
1105         srandom(sr);
1106
1107         eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
1108                                       EAP_VENDOR_IETF, EAP_TYPE_PWD,
1109                                       "PWD");
1110         if (eap == NULL)
1111                 return -1;
1112
1113         eap->init = eap_pwd_init;
1114         eap->reset = eap_pwd_reset;
1115         eap->buildReq = eap_pwd_build_req;
1116         eap->check = eap_pwd_check;
1117         eap->process = eap_pwd_process;
1118         eap->isDone = eap_pwd_is_done;
1119         eap->getKey = eap_pwd_getkey;
1120         eap->get_emsk = eap_pwd_get_emsk;
1121         eap->isSuccess = eap_pwd_is_success;
1122         eap->getSessionId = eap_pwd_get_session_id;
1123
1124         ret = eap_server_method_register(eap);
1125         if (ret)
1126                 eap_server_method_free(eap);
1127         return ret;
1128 }
1129