lib/gnutls_kx.c

   1 /*
   2  * Copyright (C) 2000-2012 Free Software Foundation, Inc.
   3  *
   4  * Author: Nikos Mavrogiannopoulos
   5  *
   6  * This file is part of GnuTLS.
   7  *
   8  * The GnuTLS is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * as published by the Free Software Foundation; either version 3 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>
  20  *
  21  */
  22
  23 /* This file contains functions which are wrappers for the key exchange
  24  * part of TLS. They are called by the handshake functions (gnutls_handshake)
  25  */
  26
  27 #include "gnutls_int.h"
  28 #include "gnutls_handshake.h"
  29 #include "gnutls_kx.h"
  30 #include "gnutls_dh.h"
  31 #include "gnutls_errors.h"
  32 #include "algorithms.h"
  33 #include "debug.h"
  34 #include "gnutls_mpi.h"
  35 #include <gnutls_state.h>
  36 #include <gnutls_datum.h>
  37 #include <gnutls_rsa_export.h>
  38 #include <gnutls_mbuffers.h>
  39
  40 /* This is a temporary function to be used before the generate_*
  41    internal API is changed to use mbuffers. For now we don't avoid the
  42    extra alloc + memcpy. */
  43 static inline int
  44 send_handshake (gnutls_session_t session, uint8_t * data, size_t size,
  45                 gnutls_handshake_description_t type)
  46 {
  47   mbuffer_st *bufel;
  48
  49   if (data == NULL && size == 0)
  50     return _gnutls_send_handshake (session, NULL, type);
  51
  52   if (data == NULL && size > 0)
  53     {
  54       gnutls_assert ();
  55       return GNUTLS_E_INVALID_REQUEST;
  56     }
  57
  58   bufel = _gnutls_handshake_alloc(session, size, size);
  59   if (bufel == NULL)
  60     {
  61       gnutls_assert ();
  62       return GNUTLS_E_MEMORY_ERROR;
  63     }
  64
  65   _mbuffer_set_udata (bufel, data, size);
  66
  67   return _gnutls_send_handshake (session, bufel, type);
  68 }
  69
  70
  71 /* This file contains important thing for the TLS handshake procedure.
  72  */
  73
  74 #define MASTER_SECRET "master secret"
  75 #define MASTER_SECRET_SIZE (sizeof(MASTER_SECRET)-1)
  76 static int generate_normal_master (gnutls_session_t session, gnutls_datum_t*, int);
  77
  78 int
  79 _gnutls_generate_master (gnutls_session_t session, int keep_premaster)
  80 {
  81   if (session->internals.resumed == RESUME_FALSE)
  82     return generate_normal_master (session, &session->key.key, keep_premaster);
  83   else if (session->internals.premaster_set)
  84     {
  85       gnutls_datum_t premaster;
  86       premaster.size = sizeof(session->internals.resumed_security_parameters.master_secret);
  87       premaster.data = session->internals.resumed_security_parameters.master_secret;
  88       return generate_normal_master(session, &premaster, 1);
  89     }
  90   return 0;
  91 }
  92
  93 /* here we generate the TLS Master secret.
  94  */
  95 static int
  96 generate_normal_master (gnutls_session_t session, gnutls_datum_t *premaster,
  97                         int keep_premaster)
  98 {
  99   int ret = 0;
 100   char buf[512];
 101
 102   _gnutls_hard_log ("INT: PREMASTER SECRET[%d]: %s\n", premaster->size,
 103                     _gnutls_bin2hex (premaster->data, premaster->size, buf,
 104                                      sizeof (buf), NULL));
 105   _gnutls_hard_log ("INT: CLIENT RANDOM[%d]: %s\n", 32,
 106                     _gnutls_bin2hex (session->
 107                                      security_parameters.client_random, 32,
 108                                      buf, sizeof (buf), NULL));
 109   _gnutls_hard_log ("INT: SERVER RANDOM[%d]: %s\n", 32,
 110                     _gnutls_bin2hex (session->
 111                                      security_parameters.server_random, 32,
 112                                      buf, sizeof (buf), NULL));
 113
 114   if (gnutls_protocol_get_version (session) == GNUTLS_SSL3)
 115     {
 116       uint8_t rnd[2 * GNUTLS_RANDOM_SIZE + 1];
 117
 118       memcpy (rnd, session->security_parameters.client_random,
 119               GNUTLS_RANDOM_SIZE);
 120       memcpy (&rnd[GNUTLS_RANDOM_SIZE],
 121               session->security_parameters.server_random, GNUTLS_RANDOM_SIZE);
 122
 123       ret =
 124         _gnutls_ssl3_generate_random (premaster->data, premaster->size,
 125                                       rnd, 2 * GNUTLS_RANDOM_SIZE,
 126                                       GNUTLS_MASTER_SIZE,
 127                                       session->
 128                                       security_parameters.master_secret);
 129
 130     }
 131   else
 132     {
 133       uint8_t rnd[2 * GNUTLS_RANDOM_SIZE + 1];
 134
 135       memcpy (rnd, session->security_parameters.client_random,
 136               GNUTLS_RANDOM_SIZE);
 137       memcpy (&rnd[GNUTLS_RANDOM_SIZE],
 138               session->security_parameters.server_random, GNUTLS_RANDOM_SIZE);
 139
 140       ret =
 141         _gnutls_PRF (session, premaster->data, premaster->size,
 142                      MASTER_SECRET, MASTER_SECRET_SIZE,
 143                      rnd, 2 * GNUTLS_RANDOM_SIZE, GNUTLS_MASTER_SIZE,
 144                      session->security_parameters.master_secret);
 145     }
 146
 147   if (!keep_premaster)
 148     _gnutls_free_datum (premaster);
 149
 150   if (ret < 0)
 151     return ret;
 152
 153   _gnutls_hard_log ("INT: MASTER SECRET: %s\n",
 154                     _gnutls_bin2hex (session->
 155                                      security_parameters.master_secret,
 156                                      GNUTLS_MASTER_SIZE, buf, sizeof (buf),
 157                                      NULL));
 158
 159   return ret;
 160 }
 161
 162
 163 /* This is called when we want to receive the key exchange message of the
 164  * server. It does nothing if this type of message is not required
 165  * by the selected ciphersuite.
 166  */
 167 int
 168 _gnutls_send_server_kx_message (gnutls_session_t session, int again)
 169 {
 170   gnutls_buffer_st data;
 171   int ret = 0;
 172
 173   if (session->internals.auth_struct->gnutls_generate_server_kx == NULL)
 174     return 0;
 175
 176   _gnutls_buffer_init( &data);
 177
 178   if (again == 0)
 179     {
 180       ret =
 181         session->internals.auth_struct->gnutls_generate_server_kx (session,
 182                                                                    &data);
 183
 184       if (ret == GNUTLS_E_INT_RET_0)
 185         {
 186           gnutls_assert ();
 187           ret = 0;
 188           goto cleanup;
 189         }
 190
 191       if (ret < 0)
 192         {
 193           gnutls_assert ();
 194           goto cleanup;
 195         }
 196     }
 197
 198   ret = send_handshake (session, data.data, data.length,
 199                         GNUTLS_HANDSHAKE_SERVER_KEY_EXCHANGE);
 200   if (ret < 0)
 201     {
 202       gnutls_assert ();
 203     }
 204
 205 cleanup:
 206   _gnutls_buffer_clear (&data);
 207   return ret;
 208 }
 209
 210 /* This function sends a certificate request message to the
 211  * client.
 212  */
 213 int
 214 _gnutls_send_server_crt_request (gnutls_session_t session, int again)
 215 {
 216   gnutls_buffer_st data;
 217   int ret = 0;
 218
 219   if (session->internals.
 220       auth_struct->gnutls_generate_server_crt_request == NULL)
 221     return 0;
 222
 223   if (session->internals.send_cert_req <= 0)
 224     return 0;
 225
 226   _gnutls_buffer_init( &data);
 227
 228   if (again == 0)
 229     {
 230       ret =
 231         session->internals.
 232         auth_struct->gnutls_generate_server_crt_request (session,
 233                                                                  &data);
 234
 235       if (ret < 0)
 236         {
 237           gnutls_assert ();
 238           goto cleanup;
 239         }
 240     }
 241
 242   ret = send_handshake (session, data.data, data.length,
 243                         GNUTLS_HANDSHAKE_CERTIFICATE_REQUEST);
 244   if (ret < 0)
 245     {
 246       gnutls_assert ();
 247     }
 248
 249 cleanup:
 250   _gnutls_buffer_clear (&data);
 251   return ret;
 252 }
 253
 254
 255 /* This is the function for the client to send the key
 256  * exchange message
 257  */
 258 int
 259 _gnutls_send_client_kx_message (gnutls_session_t session, int again)
 260 {
 261   gnutls_buffer_st data;
 262   int ret = 0;
 263
 264   if (session->internals.auth_struct->gnutls_generate_client_kx == NULL)
 265     return 0;
 266
 267   _gnutls_buffer_init( &data);
 268
 269   if (again == 0)
 270     {
 271       ret =
 272         session->internals.auth_struct->gnutls_generate_client_kx (session,
 273                                                                    &data);
 274       if (ret < 0)
 275         {
 276           gnutls_assert();
 277           goto cleanup;
 278         }
 279     }
 280   ret = send_handshake (session, data.data, data.length,
 281                         GNUTLS_HANDSHAKE_CLIENT_KEY_EXCHANGE);
 282   if (ret < 0)
 283     {
 284       gnutls_assert ();
 285     }
 286
 287 cleanup:
 288   _gnutls_buffer_clear (&data);
 289   return ret;
 290 }
 291
 292
 293 /* This is the function for the client to send the certificate
 294  * verify message
 295  */
 296 int
 297 _gnutls_send_client_certificate_verify (gnutls_session_t session, int again)
 298 {
 299   gnutls_buffer_st data;
 300   int ret = 0;
 301
 302   /* This is a packet that is only sent by the client
 303    */
 304   if (session->security_parameters.entity == GNUTLS_SERVER)
 305     return 0;
 306
 307   /* if certificate verify is not needed just exit
 308    */
 309   if (session->key.crt_requested == 0)
 310     return 0;
 311
 312
 313   if (session->internals.auth_struct->gnutls_generate_client_crt_vrfy ==
 314       NULL)
 315     {
 316       gnutls_assert ();
 317       return 0;                 /* this algorithm does not support cli_crt_vrfy
 318                                  */
 319     }
 320
 321   _gnutls_buffer_init( &data);
 322
 323   if (again == 0)
 324     {
 325       ret =
 326         session->internals.
 327         auth_struct->gnutls_generate_client_crt_vrfy (session, &data);
 328       if (ret < 0)
 329         {
 330           gnutls_assert();
 331           goto cleanup;
 332         }
 333
 334       if (ret == 0)
 335           goto cleanup;
 336
 337     }
 338   ret = send_handshake (session, data.data, data.length,
 339                         GNUTLS_HANDSHAKE_CERTIFICATE_VERIFY);
 340
 341   if (ret < 0)
 342     {
 343       gnutls_assert ();
 344     }
 345
 346 cleanup:
 347   _gnutls_buffer_clear (&data);
 348   return ret;
 349 }
 350
 351 /* This is called when we want send our certificate
 352  */
 353 int
 354 _gnutls_send_client_certificate (gnutls_session_t session, int again)
 355 {
 356   gnutls_buffer_st data;
 357   int ret = 0;
 358
 359
 360   if (session->key.crt_requested == 0)
 361     return 0;
 362
 363   if (session->internals.auth_struct->gnutls_generate_client_certificate ==
 364       NULL)
 365     return 0;
 366
 367   _gnutls_buffer_init( &data);
 368
 369   if (again == 0)
 370     {
 371       if (gnutls_protocol_get_version (session) != GNUTLS_SSL3 ||
 372           session->internals.selected_cert_list_length > 0)
 373         {
 374           /* TLS 1.0 or SSL 3.0 with a valid certificate
 375            */
 376           ret =
 377             session->internals.
 378             auth_struct->gnutls_generate_client_certificate (session, &data);
 379
 380           if (ret < 0)
 381             {
 382               gnutls_assert();
 383               goto cleanup;
 384             }
 385         }
 386     }
 387
 388   /* In the SSL 3.0 protocol we need to send a
 389    * no certificate alert instead of an
 390    * empty certificate.
 391    */
 392   if (gnutls_protocol_get_version (session) == GNUTLS_SSL3 &&
 393       session->internals.selected_cert_list_length == 0)
 394     {
 395       ret =
 396         gnutls_alert_send (session, GNUTLS_AL_WARNING,
 397                            GNUTLS_A_SSL3_NO_CERTIFICATE);
 398
 399     }
 400   else
 401     {                           /* TLS 1.0 or SSL 3.0 with a valid certificate
 402                                  */
 403       ret = send_handshake (session, data.data, data.length,
 404                             GNUTLS_HANDSHAKE_CERTIFICATE_PKT);
 405     }
 406
 407 cleanup:
 408   _gnutls_buffer_clear (&data);
 409   return ret;
 410 }
 411
 412
 413 /* This is called when we want send our certificate
 414  */
 415 int
 416 _gnutls_send_server_certificate (gnutls_session_t session, int again)
 417 {
 418   gnutls_buffer_st data;
 419   int ret = 0;
 420
 421
 422   if (session->internals.auth_struct->gnutls_generate_server_certificate ==
 423       NULL)
 424     return 0;
 425
 426   _gnutls_buffer_init( &data);
 427
 428   if (again == 0)
 429     {
 430       ret =
 431         session->internals.
 432         auth_struct->gnutls_generate_server_certificate (session, &data);
 433
 434         if (ret < 0)
 435           {
 436             gnutls_assert();
 437             goto cleanup;
 438           }
 439     }
 440   ret = send_handshake (session, data.data, data.length,
 441                         GNUTLS_HANDSHAKE_CERTIFICATE_PKT);
 442   if (ret < 0)
 443     {
 444       gnutls_assert ();
 445     }
 446
 447 cleanup:
 448   _gnutls_buffer_clear (&data);
 449   return ret;
 450 }
 451
 452
 453 int
 454 _gnutls_recv_server_kx_message (gnutls_session_t session)
 455 {
 456   gnutls_buffer_st buf;
 457   int ret = 0;
 458   unsigned int optflag = 0;
 459
 460   if (session->internals.auth_struct->gnutls_process_server_kx != NULL)
 461     {
 462
 463       /* EXCEPTION FOR RSA_EXPORT cipher suite
 464        */
 465       if (_gnutls_session_is_export (session) != 0 &&
 466           _gnutls_peers_cert_less_512 (session) != 0)
 467         {
 468           gnutls_assert ();
 469           return 0;
 470         }
 471
 472       /* Server key exchange packet is optional for PSK. */
 473       if (_gnutls_session_is_psk (session))
 474         optflag = 1;
 475
 476       ret =
 477         _gnutls_recv_handshake (session,
 478                                 GNUTLS_HANDSHAKE_SERVER_KEY_EXCHANGE,
 479                                 optflag, &buf);
 480       if (ret < 0)
 481         {
 482           gnutls_assert ();
 483           return ret;
 484         }
 485
 486       ret =
 487         session->internals.auth_struct->gnutls_process_server_kx (session,
 488                                                                   buf.data,
 489                                                                   buf.length);
 490       _gnutls_buffer_clear(&buf);
 491
 492       if (ret < 0)
 493         {
 494           gnutls_assert ();
 495           return ret;
 496         }
 497
 498     }
 499   return ret;
 500 }
 501
 502 int
 503 _gnutls_recv_server_crt_request (gnutls_session_t session)
 504 {
 505   gnutls_buffer_st buf;
 506   int ret = 0;
 507
 508   if (session->internals.
 509       auth_struct->gnutls_process_server_crt_request != NULL)
 510     {
 511
 512       ret =
 513         _gnutls_recv_handshake (session,
 514                                 GNUTLS_HANDSHAKE_CERTIFICATE_REQUEST,
 515                                 1, &buf);
 516       if (ret < 0)
 517         return ret;
 518
 519       if (ret == 0 && buf.length == 0)
 520         {
 521           _gnutls_buffer_clear(&buf);
 522           return 0;               /* ignored */
 523         }
 524
 525       ret =
 526         session->internals.
 527         auth_struct->gnutls_process_server_crt_request (session, buf.data,
 528                                                                 buf.length);
 529       _gnutls_buffer_clear (&buf);
 530       if (ret < 0)
 531         return ret;
 532
 533     }
 534   return ret;
 535 }
 536
 537 int
 538 _gnutls_recv_client_kx_message (gnutls_session_t session)
 539 {
 540   gnutls_buffer_st buf;
 541   int ret = 0;
 542
 543
 544   /* Do key exchange only if the algorithm permits it */
 545   if (session->internals.auth_struct->gnutls_process_client_kx != NULL)
 546     {
 547
 548       ret =
 549         _gnutls_recv_handshake (session,
 550                                 GNUTLS_HANDSHAKE_CLIENT_KEY_EXCHANGE,
 551                                 0, &buf);
 552       if (ret < 0)
 553         return ret;
 554
 555       ret =
 556         session->internals.auth_struct->gnutls_process_client_kx (session,
 557                                                                   buf.data,
 558                                                                   buf.length);
 559       _gnutls_buffer_clear (&buf);
 560       if (ret < 0)
 561         return ret;
 562
 563     }
 564
 565   return ret;
 566 }
 567
 568
 569 int
 570 _gnutls_recv_client_certificate (gnutls_session_t session)
 571 {
 572   gnutls_buffer_st buf;
 573   int ret = 0;
 574   int optional;
 575
 576   if (session->internals.auth_struct->gnutls_process_client_certificate ==
 577       NULL)
 578     return 0;
 579
 580   /* if we have not requested a certificate then just return
 581    */
 582   if (session->internals.send_cert_req == 0)
 583     {
 584       return 0;
 585     }
 586
 587   if (session->internals.send_cert_req == GNUTLS_CERT_REQUIRE)
 588     optional = 0;
 589   else
 590     optional = 1;
 591
 592   ret =
 593     _gnutls_recv_handshake (session, GNUTLS_HANDSHAKE_CERTIFICATE_PKT,
 594       optional, &buf);
 595
 596   if (ret < 0)
 597     {
 598       /* Handle the case of old SSL3 clients who send
 599        * a warning alert instead of an empty certificate to indicate
 600        * no certificate.
 601        */
 602       if (optional != 0 &&
 603           ret == GNUTLS_E_WARNING_ALERT_RECEIVED &&
 604           gnutls_protocol_get_version (session) == GNUTLS_SSL3 &&
 605           gnutls_alert_get (session) == GNUTLS_A_SSL3_NO_CERTIFICATE)
 606         {
 607
 608           /* SSL3 does not send an empty certificate,
 609            * but this alert. So we just ignore it.
 610            */
 611           gnutls_assert ();
 612           return 0;
 613         }
 614
 615       /* certificate was required
 616        */
 617       if ((ret == GNUTLS_E_WARNING_ALERT_RECEIVED
 618            || ret == GNUTLS_E_FATAL_ALERT_RECEIVED)
 619           && optional == 0)
 620         {
 621           gnutls_assert ();
 622           return GNUTLS_E_NO_CERTIFICATE_FOUND;
 623         }
 624
 625       return ret;
 626     }
 627
 628   if (ret == 0 && buf.length == 0 && optional != 0)
 629     {
 630       /* Client has not sent the certificate message.
 631        * well I'm not sure we should accept this
 632        * behaviour.
 633        */
 634       gnutls_assert ();
 635       ret = 0;
 636       goto cleanup;
 637     }
 638   ret =
 639     session->internals.
 640     auth_struct->gnutls_process_client_certificate (session, buf.data,
 641                                                     buf.length);
 642
 643   if (ret < 0 && ret != GNUTLS_E_NO_CERTIFICATE_FOUND)
 644     {
 645       gnutls_assert ();
 646       goto cleanup;
 647     }
 648
 649   /* ok we should expect a certificate verify message now
 650    */
 651   if (ret == GNUTLS_E_NO_CERTIFICATE_FOUND && optional != 0)
 652     ret = 0;
 653   else
 654     session->key.crt_requested = 1;
 655
 656 cleanup:
 657   _gnutls_buffer_clear(&buf);
 658   return ret;
 659 }
 660
 661 int
 662 _gnutls_recv_server_certificate (gnutls_session_t session)
 663 {
 664   gnutls_buffer_st buf;
 665   int ret = 0;
 666
 667   if (session->internals.auth_struct->gnutls_process_server_certificate !=
 668       NULL)
 669     {
 670
 671       ret =
 672         _gnutls_recv_handshake (session,
 673                                 GNUTLS_HANDSHAKE_CERTIFICATE_PKT,
 674                                 0, &buf);
 675       if (ret < 0)
 676         {
 677           gnutls_assert ();
 678           return ret;
 679         }
 680
 681       ret =
 682         session->internals.
 683         auth_struct->gnutls_process_server_certificate (session, buf.data,
 684                                                         buf.length);
 685       _gnutls_buffer_clear(&buf);
 686       if (ret < 0)
 687         {
 688           gnutls_assert ();
 689           return ret;
 690         }
 691     }
 692
 693   return ret;
 694 }
 695
 696
 697 /* Recv the client certificate verify. This packet may not
 698  * arrive if the peer did not send us a certificate.
 699  */
 700 int
 701 _gnutls_recv_client_certificate_verify_message (gnutls_session_t session)
 702 {
 703   gnutls_buffer_st buf;
 704   int ret = 0;
 705
 706
 707   if (session->internals.auth_struct->gnutls_process_client_crt_vrfy == NULL)
 708     return 0;
 709
 710   if (session->internals.send_cert_req == 0 ||
 711       session->key.crt_requested == 0)
 712     {
 713       return 0;
 714     }
 715
 716   ret =
 717     _gnutls_recv_handshake (session,
 718                             GNUTLS_HANDSHAKE_CERTIFICATE_VERIFY,
 719                             1, &buf);
 720   if (ret < 0)
 721     return ret;
 722
 723   if (ret == 0 && buf.length == 0
 724       && session->internals.send_cert_req == GNUTLS_CERT_REQUIRE)
 725     {
 726       /* certificate was required */
 727       gnutls_assert ();
 728       ret = GNUTLS_E_NO_CERTIFICATE_FOUND;
 729       goto cleanup;
 730     }
 731
 732   ret =
 733     session->internals.
 734     auth_struct->gnutls_process_client_crt_vrfy (session, buf.data,
 735                                                   buf.length);
 736
 737 cleanup:
 738   _gnutls_buffer_clear(&buf);
 739   return ret;
 740 }