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