crypto/tlssession.c

   1 /*
   2  * QEMU crypto TLS session support
   3  *
   4  * Copyright (c) 2015 Red Hat, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "crypto/tlssession.h"
  23 #include "crypto/tlscredsanon.h"
  24 #include "crypto/tlscredspsk.h"
  25 #include "crypto/tlscredsx509.h"
  26 #include "qapi/error.h"
  27 #include "qemu/acl.h"
  28 #include "trace.h"
  29
  30 #ifdef CONFIG_GNUTLS
  31
  32
  33 #include <gnutls/x509.h>
  34
  35
  36 struct QCryptoTLSSession {
  37     QCryptoTLSCreds *creds;
  38     gnutls_session_t handle;
  39     char *hostname;
  40     char *aclname;
  41     bool handshakeComplete;
  42     QCryptoTLSSessionWriteFunc writeFunc;
  43     QCryptoTLSSessionReadFunc readFunc;
  44     void *opaque;
  45     char *peername;
  46 };
  47
  48
  49 void
  50 qcrypto_tls_session_free(QCryptoTLSSession *session)
  51 {
  52     if (!session) {
  53         return;
  54     }
  55
  56     gnutls_deinit(session->handle);
  57     g_free(session->hostname);
  58     g_free(session->peername);
  59     g_free(session->aclname);
  60     object_unref(OBJECT(session->creds));
  61     g_free(session);
  62 }
  63
  64
  65 static ssize_t
  66 qcrypto_tls_session_push(void *opaque, const void *buf, size_t len)
  67 {
  68     QCryptoTLSSession *session = opaque;
  69
  70     if (!session->writeFunc) {
  71         errno = EIO;
  72         return -1;
  73     };
  74
  75     return session->writeFunc(buf, len, session->opaque);
  76 }
  77
  78
  79 static ssize_t
  80 qcrypto_tls_session_pull(void *opaque, void *buf, size_t len)
  81 {
  82     QCryptoTLSSession *session = opaque;
  83
  84     if (!session->readFunc) {
  85         errno = EIO;
  86         return -1;
  87     };
  88
  89     return session->readFunc(buf, len, session->opaque);
  90 }
  91
  92 #define TLS_PRIORITY_ADDITIONAL_ANON "+ANON-DH"
  93 #define TLS_PRIORITY_ADDITIONAL_PSK "+ECDHE-PSK:+DHE-PSK:+PSK"
  94
  95 QCryptoTLSSession *
  96 qcrypto_tls_session_new(QCryptoTLSCreds *creds,
  97                         const char *hostname,
  98                         const char *aclname,
  99                         QCryptoTLSCredsEndpoint endpoint,
 100                         Error **errp)
 101 {
 102     QCryptoTLSSession *session;
 103     int ret;
 104
 105     session = g_new0(QCryptoTLSSession, 1);
 106     trace_qcrypto_tls_session_new(
 107         session, creds, hostname ? hostname : "<none>",
 108         aclname ? aclname : "<none>", endpoint);
 109
 110     if (hostname) {
 111         session->hostname = g_strdup(hostname);
 112     }
 113     if (aclname) {
 114         session->aclname = g_strdup(aclname);
 115     }
 116     session->creds = creds;
 117     object_ref(OBJECT(creds));
 118
 119     if (creds->endpoint != endpoint) {
 120         error_setg(errp, "Credentials endpoint doesn't match session");
 121         goto error;
 122     }
 123
 124     if (endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 125         ret = gnutls_init(&session->handle, GNUTLS_SERVER);
 126     } else {
 127         ret = gnutls_init(&session->handle, GNUTLS_CLIENT);
 128     }
 129     if (ret < 0) {
 130         error_setg(errp, "Cannot initialize TLS session: %s",
 131                    gnutls_strerror(ret));
 132         goto error;
 133     }
 134
 135     if (object_dynamic_cast(OBJECT(creds),
 136                             TYPE_QCRYPTO_TLS_CREDS_ANON)) {
 137         QCryptoTLSCredsAnon *acreds = QCRYPTO_TLS_CREDS_ANON(creds);
 138         char *prio;
 139
 140         if (creds->priority != NULL) {
 141             prio = g_strdup_printf("%s:%s",
 142                                    creds->priority,
 143                                    TLS_PRIORITY_ADDITIONAL_ANON);
 144         } else {
 145             prio = g_strdup(CONFIG_TLS_PRIORITY ":"
 146                             TLS_PRIORITY_ADDITIONAL_ANON);
 147         }
 148
 149         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
 150         if (ret < 0) {
 151             error_setg(errp, "Unable to set TLS session priority %s: %s",
 152                        prio, gnutls_strerror(ret));
 153             g_free(prio);
 154             goto error;
 155         }
 156         g_free(prio);
 157         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 158             ret = gnutls_credentials_set(session->handle,
 159                                          GNUTLS_CRD_ANON,
 160                                          acreds->data.server);
 161         } else {
 162             ret = gnutls_credentials_set(session->handle,
 163                                          GNUTLS_CRD_ANON,
 164                                          acreds->data.client);
 165         }
 166         if (ret < 0) {
 167             error_setg(errp, "Cannot set session credentials: %s",
 168                        gnutls_strerror(ret));
 169             goto error;
 170         }
 171     } else if (object_dynamic_cast(OBJECT(creds),
 172                                    TYPE_QCRYPTO_TLS_CREDS_PSK)) {
 173         QCryptoTLSCredsPSK *pcreds = QCRYPTO_TLS_CREDS_PSK(creds);
 174         char *prio;
 175
 176         if (creds->priority != NULL) {
 177             prio = g_strdup_printf("%s:%s",
 178                                    creds->priority,
 179                                    TLS_PRIORITY_ADDITIONAL_PSK);
 180         } else {
 181             prio = g_strdup(CONFIG_TLS_PRIORITY ":"
 182                             TLS_PRIORITY_ADDITIONAL_PSK);
 183         }
 184
 185         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
 186         if (ret < 0) {
 187             error_setg(errp, "Unable to set TLS session priority %s: %s",
 188                        prio, gnutls_strerror(ret));
 189             g_free(prio);
 190             goto error;
 191         }
 192         g_free(prio);
 193         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 194             ret = gnutls_credentials_set(session->handle,
 195                                          GNUTLS_CRD_PSK,
 196                                          pcreds->data.server);
 197         } else {
 198             ret = gnutls_credentials_set(session->handle,
 199                                          GNUTLS_CRD_PSK,
 200                                          pcreds->data.client);
 201         }
 202         if (ret < 0) {
 203             error_setg(errp, "Cannot set session credentials: %s",
 204                        gnutls_strerror(ret));
 205             goto error;
 206         }
 207     } else if (object_dynamic_cast(OBJECT(creds),
 208                                    TYPE_QCRYPTO_TLS_CREDS_X509)) {
 209         QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
 210         const char *prio = creds->priority;
 211         if (!prio) {
 212             prio = CONFIG_TLS_PRIORITY;
 213         }
 214
 215         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
 216         if (ret < 0) {
 217             error_setg(errp, "Cannot set default TLS session priority %s: %s",
 218                        prio, gnutls_strerror(ret));
 219             goto error;
 220         }
 221         ret = gnutls_credentials_set(session->handle,
 222                                      GNUTLS_CRD_CERTIFICATE,
 223                                      tcreds->data);
 224         if (ret < 0) {
 225             error_setg(errp, "Cannot set session credentials: %s",
 226                        gnutls_strerror(ret));
 227             goto error;
 228         }
 229
 230         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 231             /* This requests, but does not enforce a client cert.
 232              * The cert checking code later does enforcement */
 233             gnutls_certificate_server_set_request(session->handle,
 234                                                   GNUTLS_CERT_REQUEST);
 235         }
 236     } else {
 237         error_setg(errp, "Unsupported TLS credentials type %s",
 238                    object_get_typename(OBJECT(creds)));
 239         goto error;
 240     }
 241
 242     gnutls_transport_set_ptr(session->handle, session);
 243     gnutls_transport_set_push_function(session->handle,
 244                                        qcrypto_tls_session_push);
 245     gnutls_transport_set_pull_function(session->handle,
 246                                        qcrypto_tls_session_pull);
 247
 248     return session;
 249
 250  error:
 251     qcrypto_tls_session_free(session);
 252     return NULL;
 253 }
 254
 255 static int
 256 qcrypto_tls_session_check_certificate(QCryptoTLSSession *session,
 257                                       Error **errp)
 258 {
 259     int ret;
 260     unsigned int status;
 261     const gnutls_datum_t *certs;
 262     unsigned int nCerts, i;
 263     time_t now;
 264     gnutls_x509_crt_t cert = NULL;
 265
 266     now = time(NULL);
 267     if (now == ((time_t)-1)) {
 268         error_setg_errno(errp, errno, "Cannot get current time");
 269         return -1;
 270     }
 271
 272     ret = gnutls_certificate_verify_peers2(session->handle, &status);
 273     if (ret < 0) {
 274         error_setg(errp, "Verify failed: %s", gnutls_strerror(ret));
 275         return -1;
 276     }
 277
 278     if (status != 0) {
 279         const char *reason = "Invalid certificate";
 280
 281         if (status & GNUTLS_CERT_INVALID) {
 282             reason = "The certificate is not trusted";
 283         }
 284
 285         if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) {
 286             reason = "The certificate hasn't got a known issuer";
 287         }
 288
 289         if (status & GNUTLS_CERT_REVOKED) {
 290             reason = "The certificate has been revoked";
 291         }
 292
 293         if (status & GNUTLS_CERT_INSECURE_ALGORITHM) {
 294             reason = "The certificate uses an insecure algorithm";
 295         }
 296
 297         error_setg(errp, "%s", reason);
 298         return -1;
 299     }
 300
 301     certs = gnutls_certificate_get_peers(session->handle, &nCerts);
 302     if (!certs) {
 303         error_setg(errp, "No certificate peers");
 304         return -1;
 305     }
 306
 307     for (i = 0; i < nCerts; i++) {
 308         ret = gnutls_x509_crt_init(&cert);
 309         if (ret < 0) {
 310             error_setg(errp, "Cannot initialize certificate: %s",
 311                        gnutls_strerror(ret));
 312             return -1;
 313         }
 314
 315         ret = gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER);
 316         if (ret < 0) {
 317             error_setg(errp, "Cannot import certificate: %s",
 318                        gnutls_strerror(ret));
 319             goto error;
 320         }
 321
 322         if (gnutls_x509_crt_get_expiration_time(cert) < now) {
 323             error_setg(errp, "The certificate has expired");
 324             goto error;
 325         }
 326
 327         if (gnutls_x509_crt_get_activation_time(cert) > now) {
 328             error_setg(errp, "The certificate is not yet activated");
 329             goto error;
 330         }
 331
 332         if (gnutls_x509_crt_get_activation_time(cert) > now) {
 333             error_setg(errp, "The certificate is not yet activated");
 334             goto error;
 335         }
 336
 337         if (i == 0) {
 338             size_t dnameSize = 1024;
 339             session->peername = g_malloc(dnameSize);
 340         requery:
 341             ret = gnutls_x509_crt_get_dn(cert, session->peername, &dnameSize);
 342             if (ret < 0) {
 343                 if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
 344                     session->peername = g_realloc(session->peername,
 345                                                   dnameSize);
 346                     goto requery;
 347                 }
 348                 error_setg(errp, "Cannot get client distinguished name: %s",
 349                            gnutls_strerror(ret));
 350                 goto error;
 351             }
 352             if (session->aclname) {
 353                 qemu_acl *acl = qemu_acl_find(session->aclname);
 354                 int allow;
 355                 if (!acl) {
 356                     error_setg(errp, "Cannot find ACL %s",
 357                                session->aclname);
 358                     goto error;
 359                 }
 360
 361                 allow = qemu_acl_party_is_allowed(acl, session->peername);
 362
 363                 if (!allow) {
 364                     error_setg(errp, "TLS x509 ACL check for %s is denied",
 365                                session->peername);
 366                     goto error;
 367                 }
 368             }
 369             if (session->hostname) {
 370                 if (!gnutls_x509_crt_check_hostname(cert, session->hostname)) {
 371                     error_setg(errp,
 372                                "Certificate does not match the hostname %s",
 373                                session->hostname);
 374                     goto error;
 375                 }
 376             }
 377         }
 378
 379         gnutls_x509_crt_deinit(cert);
 380     }
 381
 382     return 0;
 383
 384  error:
 385     gnutls_x509_crt_deinit(cert);
 386     return -1;
 387 }
 388
 389
 390 int
 391 qcrypto_tls_session_check_credentials(QCryptoTLSSession *session,
 392                                       Error **errp)
 393 {
 394     if (object_dynamic_cast(OBJECT(session->creds),
 395                             TYPE_QCRYPTO_TLS_CREDS_ANON)) {
 396         trace_qcrypto_tls_session_check_creds(session, "nop");
 397         return 0;
 398     } else if (object_dynamic_cast(OBJECT(session->creds),
 399                             TYPE_QCRYPTO_TLS_CREDS_PSK)) {
 400         trace_qcrypto_tls_session_check_creds(session, "nop");
 401         return 0;
 402     } else if (object_dynamic_cast(OBJECT(session->creds),
 403                             TYPE_QCRYPTO_TLS_CREDS_X509)) {
 404         if (session->creds->verifyPeer) {
 405             int ret = qcrypto_tls_session_check_certificate(session,
 406                                                             errp);
 407             trace_qcrypto_tls_session_check_creds(session,
 408                                                   ret == 0 ? "pass" : "fail");
 409             return ret;
 410         } else {
 411             trace_qcrypto_tls_session_check_creds(session, "skip");
 412             return 0;
 413         }
 414     } else {
 415         trace_qcrypto_tls_session_check_creds(session, "error");
 416         error_setg(errp, "Unexpected credential type %s",
 417                    object_get_typename(OBJECT(session->creds)));
 418         return -1;
 419     }
 420 }
 421
 422
 423 void
 424 qcrypto_tls_session_set_callbacks(QCryptoTLSSession *session,
 425                                   QCryptoTLSSessionWriteFunc writeFunc,
 426                                   QCryptoTLSSessionReadFunc readFunc,
 427                                   void *opaque)
 428 {
 429     session->writeFunc = writeFunc;
 430     session->readFunc = readFunc;
 431     session->opaque = opaque;
 432 }
 433
 434
 435 ssize_t
 436 qcrypto_tls_session_write(QCryptoTLSSession *session,
 437                           const char *buf,
 438                           size_t len)
 439 {
 440     ssize_t ret = gnutls_record_send(session->handle, buf, len);
 441
 442     if (ret < 0) {
 443         switch (ret) {
 444         case GNUTLS_E_AGAIN:
 445             errno = EAGAIN;
 446             break;
 447         case GNUTLS_E_INTERRUPTED:
 448             errno = EINTR;
 449             break;
 450         default:
 451             errno = EIO;
 452             break;
 453         }
 454         ret = -1;
 455     }
 456
 457     return ret;
 458 }
 459
 460
 461 ssize_t
 462 qcrypto_tls_session_read(QCryptoTLSSession *session,
 463                          char *buf,
 464                          size_t len)
 465 {
 466     ssize_t ret = gnutls_record_recv(session->handle, buf, len);
 467
 468     if (ret < 0) {
 469         switch (ret) {
 470         case GNUTLS_E_AGAIN:
 471             errno = EAGAIN;
 472             break;
 473         case GNUTLS_E_INTERRUPTED:
 474             errno = EINTR;
 475             break;
 476         default:
 477             errno = EIO;
 478             break;
 479         }
 480         ret = -1;
 481     }
 482
 483     return ret;
 484 }
 485
 486
 487 int
 488 qcrypto_tls_session_handshake(QCryptoTLSSession *session,
 489                               Error **errp)
 490 {
 491     int ret = gnutls_handshake(session->handle);
 492     if (ret == 0) {
 493         session->handshakeComplete = true;
 494     } else {
 495         if (ret == GNUTLS_E_INTERRUPTED ||
 496             ret == GNUTLS_E_AGAIN) {
 497             ret = 1;
 498         } else {
 499             error_setg(errp, "TLS handshake failed: %s",
 500                        gnutls_strerror(ret));
 501             ret = -1;
 502         }
 503     }
 504
 505     return ret;
 506 }
 507
 508
 509 QCryptoTLSSessionHandshakeStatus
 510 qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *session)
 511 {
 512     if (session->handshakeComplete) {
 513         return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
 514     } else if (gnutls_record_get_direction(session->handle) == 0) {
 515         return QCRYPTO_TLS_HANDSHAKE_RECVING;
 516     } else {
 517         return QCRYPTO_TLS_HANDSHAKE_SENDING;
 518     }
 519 }
 520
 521
 522 int
 523 qcrypto_tls_session_get_key_size(QCryptoTLSSession *session,
 524                                  Error **errp)
 525 {
 526     gnutls_cipher_algorithm_t cipher;
 527     int ssf;
 528
 529     cipher = gnutls_cipher_get(session->handle);
 530     ssf = gnutls_cipher_get_key_size(cipher);
 531     if (!ssf) {
 532         error_setg(errp, "Cannot get TLS cipher key size");
 533         return -1;
 534     }
 535     return ssf;
 536 }
 537
 538
 539 char *
 540 qcrypto_tls_session_get_peer_name(QCryptoTLSSession *session)
 541 {
 542     if (session->peername) {
 543         return g_strdup(session->peername);
 544     }
 545     return NULL;
 546 }
 547
 548
 549 #else /* ! CONFIG_GNUTLS */
 550
 551
 552 QCryptoTLSSession *
 553 qcrypto_tls_session_new(QCryptoTLSCreds *creds G_GNUC_UNUSED,
 554                         const char *hostname G_GNUC_UNUSED,
 555                         const char *aclname G_GNUC_UNUSED,
 556                         QCryptoTLSCredsEndpoint endpoint G_GNUC_UNUSED,
 557                         Error **errp)
 558 {
 559     error_setg(errp, "TLS requires GNUTLS support");
 560     return NULL;
 561 }
 562
 563
 564 void
 565 qcrypto_tls_session_free(QCryptoTLSSession *sess G_GNUC_UNUSED)
 566 {
 567 }
 568
 569
 570 int
 571 qcrypto_tls_session_check_credentials(QCryptoTLSSession *sess G_GNUC_UNUSED,
 572                                       Error **errp)
 573 {
 574     error_setg(errp, "TLS requires GNUTLS support");
 575     return -1;
 576 }
 577
 578
 579 void
 580 qcrypto_tls_session_set_callbacks(
 581     QCryptoTLSSession *sess G_GNUC_UNUSED,
 582     QCryptoTLSSessionWriteFunc writeFunc G_GNUC_UNUSED,
 583     QCryptoTLSSessionReadFunc readFunc G_GNUC_UNUSED,
 584     void *opaque G_GNUC_UNUSED)
 585 {
 586 }
 587
 588
 589 ssize_t
 590 qcrypto_tls_session_write(QCryptoTLSSession *sess,
 591                           const char *buf,
 592                           size_t len)
 593 {
 594     errno = -EIO;
 595     return -1;
 596 }
 597
 598
 599 ssize_t
 600 qcrypto_tls_session_read(QCryptoTLSSession *sess,
 601                          char *buf,
 602                          size_t len)
 603 {
 604     errno = -EIO;
 605     return -1;
 606 }
 607
 608
 609 int
 610 qcrypto_tls_session_handshake(QCryptoTLSSession *sess,
 611                               Error **errp)
 612 {
 613     error_setg(errp, "TLS requires GNUTLS support");
 614     return -1;
 615 }
 616
 617
 618 QCryptoTLSSessionHandshakeStatus
 619 qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *sess)
 620 {
 621     return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
 622 }
 623
 624
 625 int
 626 qcrypto_tls_session_get_key_size(QCryptoTLSSession *sess,
 627                                  Error **errp)
 628 {
 629     error_setg(errp, "TLS requires GNUTLS support");
 630     return -1;
 631 }
 632
 633
 634 char *
 635 qcrypto_tls_session_get_peer_name(QCryptoTLSSession *sess)
 636 {
 637     return NULL;
 638 }
 639
 640 #endif