qemu/crypto/tlssession.c
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   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 2.1 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 "authz/base.h"
  28#include "trace.h"
  29
  30#ifdef CONFIG_GNUTLS
  31
  32
  33#include <gnutls/x509.h>
  34
  35
  36struct QCryptoTLSSession {
  37    QCryptoTLSCreds *creds;
  38    gnutls_session_t handle;
  39    char *hostname;
  40    char *authzid;
  41    bool handshakeComplete;
  42    QCryptoTLSSessionWriteFunc writeFunc;
  43    QCryptoTLSSessionReadFunc readFunc;
  44    void *opaque;
  45    char *peername;
  46};
  47
  48
  49void
  50qcrypto_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->authzid);
  60    object_unref(OBJECT(session->creds));
  61    g_free(session);
  62}
  63
  64
  65static ssize_t
  66qcrypto_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
  79static ssize_t
  80qcrypto_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
  95QCryptoTLSSession *
  96qcrypto_tls_session_new(QCryptoTLSCreds *creds,
  97                        const char *hostname,
  98                        const char *authzid,
  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        authzid ? authzid : "<none>", endpoint);
 109
 110    if (hostname) {
 111        session->hostname = g_strdup(hostname);
 112    }
 113    if (authzid) {
 114        session->authzid = g_strdup(authzid);
 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
 255static int
 256qcrypto_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    Error *err = NULL;
 266
 267    now = time(NULL);
 268    if (now == ((time_t)-1)) {
 269        error_setg_errno(errp, errno, "Cannot get current time");
 270        return -1;
 271    }
 272
 273    ret = gnutls_certificate_verify_peers2(session->handle, &status);
 274    if (ret < 0) {
 275        error_setg(errp, "Verify failed: %s", gnutls_strerror(ret));
 276        return -1;
 277    }
 278
 279    if (status != 0) {
 280        const char *reason = "Invalid certificate";
 281
 282        if (status & GNUTLS_CERT_INVALID) {
 283            reason = "The certificate is not trusted";
 284        }
 285
 286        if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) {
 287            reason = "The certificate hasn't got a known issuer";
 288        }
 289
 290        if (status & GNUTLS_CERT_REVOKED) {
 291            reason = "The certificate has been revoked";
 292        }
 293
 294        if (status & GNUTLS_CERT_INSECURE_ALGORITHM) {
 295            reason = "The certificate uses an insecure algorithm";
 296        }
 297
 298        error_setg(errp, "%s", reason);
 299        return -1;
 300    }
 301
 302    certs = gnutls_certificate_get_peers(session->handle, &nCerts);
 303    if (!certs) {
 304        error_setg(errp, "No certificate peers");
 305        return -1;
 306    }
 307
 308    for (i = 0; i < nCerts; i++) {
 309        ret = gnutls_x509_crt_init(&cert);
 310        if (ret < 0) {
 311            error_setg(errp, "Cannot initialize certificate: %s",
 312                       gnutls_strerror(ret));
 313            return -1;
 314        }
 315
 316        ret = gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER);
 317        if (ret < 0) {
 318            error_setg(errp, "Cannot import certificate: %s",
 319                       gnutls_strerror(ret));
 320            goto error;
 321        }
 322
 323        if (gnutls_x509_crt_get_expiration_time(cert) < now) {
 324            error_setg(errp, "The certificate has expired");
 325            goto error;
 326        }
 327
 328        if (gnutls_x509_crt_get_activation_time(cert) > now) {
 329            error_setg(errp, "The certificate is not yet activated");
 330            goto error;
 331        }
 332
 333        if (gnutls_x509_crt_get_activation_time(cert) > now) {
 334            error_setg(errp, "The certificate is not yet activated");
 335            goto error;
 336        }
 337
 338        if (i == 0) {
 339            size_t dnameSize = 1024;
 340            session->peername = g_malloc(dnameSize);
 341        requery:
 342            ret = gnutls_x509_crt_get_dn(cert, session->peername, &dnameSize);
 343            if (ret < 0) {
 344                if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
 345                    session->peername = g_realloc(session->peername,
 346                                                  dnameSize);
 347                    goto requery;
 348                }
 349                error_setg(errp, "Cannot get client distinguished name: %s",
 350                           gnutls_strerror(ret));
 351                goto error;
 352            }
 353            if (session->authzid) {
 354                bool allow;
 355
 356                allow = qauthz_is_allowed_by_id(session->authzid,
 357                                                session->peername, &err);
 358                if (err) {
 359                    error_propagate(errp, err);
 360                    goto error;
 361                }
 362                if (!allow) {
 363                    error_setg(errp, "TLS x509 authz check for %s is denied",
 364                               session->peername);
 365                    goto error;
 366                }
 367            }
 368            if (session->hostname) {
 369                if (!gnutls_x509_crt_check_hostname(cert, session->hostname)) {
 370                    error_setg(errp,
 371                               "Certificate does not match the hostname %s",
 372                               session->hostname);
 373                    goto error;
 374                }
 375            }
 376        }
 377
 378        gnutls_x509_crt_deinit(cert);
 379    }
 380
 381    return 0;
 382
 383 error:
 384    gnutls_x509_crt_deinit(cert);
 385    return -1;
 386}
 387
 388
 389int
 390qcrypto_tls_session_check_credentials(QCryptoTLSSession *session,
 391                                      Error **errp)
 392{
 393    if (object_dynamic_cast(OBJECT(session->creds),
 394                            TYPE_QCRYPTO_TLS_CREDS_ANON)) {
 395        trace_qcrypto_tls_session_check_creds(session, "nop");
 396        return 0;
 397    } else if (object_dynamic_cast(OBJECT(session->creds),
 398                            TYPE_QCRYPTO_TLS_CREDS_PSK)) {
 399        trace_qcrypto_tls_session_check_creds(session, "nop");
 400        return 0;
 401    } else if (object_dynamic_cast(OBJECT(session->creds),
 402                            TYPE_QCRYPTO_TLS_CREDS_X509)) {
 403        if (session->creds->verifyPeer) {
 404            int ret = qcrypto_tls_session_check_certificate(session,
 405                                                            errp);
 406            trace_qcrypto_tls_session_check_creds(session,
 407                                                  ret == 0 ? "pass" : "fail");
 408            return ret;
 409        } else {
 410            trace_qcrypto_tls_session_check_creds(session, "skip");
 411            return 0;
 412        }
 413    } else {
 414        trace_qcrypto_tls_session_check_creds(session, "error");
 415        error_setg(errp, "Unexpected credential type %s",
 416                   object_get_typename(OBJECT(session->creds)));
 417        return -1;
 418    }
 419}
 420
 421
 422void
 423qcrypto_tls_session_set_callbacks(QCryptoTLSSession *session,
 424                                  QCryptoTLSSessionWriteFunc writeFunc,
 425                                  QCryptoTLSSessionReadFunc readFunc,
 426                                  void *opaque)
 427{
 428    session->writeFunc = writeFunc;
 429    session->readFunc = readFunc;
 430    session->opaque = opaque;
 431}
 432
 433
 434ssize_t
 435qcrypto_tls_session_write(QCryptoTLSSession *session,
 436                          const char *buf,
 437                          size_t len)
 438{
 439    ssize_t ret = gnutls_record_send(session->handle, buf, len);
 440
 441    if (ret < 0) {
 442        switch (ret) {
 443        case GNUTLS_E_AGAIN:
 444            errno = EAGAIN;
 445            break;
 446        case GNUTLS_E_INTERRUPTED:
 447            errno = EINTR;
 448            break;
 449        default:
 450            errno = EIO;
 451            break;
 452        }
 453        ret = -1;
 454    }
 455
 456    return ret;
 457}
 458
 459
 460ssize_t
 461qcrypto_tls_session_read(QCryptoTLSSession *session,
 462                         char *buf,
 463                         size_t len)
 464{
 465    ssize_t ret = gnutls_record_recv(session->handle, buf, len);
 466
 467    if (ret < 0) {
 468        switch (ret) {
 469        case GNUTLS_E_AGAIN:
 470            errno = EAGAIN;
 471            break;
 472        case GNUTLS_E_INTERRUPTED:
 473            errno = EINTR;
 474            break;
 475        case GNUTLS_E_PREMATURE_TERMINATION:
 476            errno = ECONNABORTED;
 477            break;
 478        default:
 479            errno = EIO;
 480            break;
 481        }
 482        ret = -1;
 483    }
 484
 485    return ret;
 486}
 487
 488
 489int
 490qcrypto_tls_session_handshake(QCryptoTLSSession *session,
 491                              Error **errp)
 492{
 493    int ret = gnutls_handshake(session->handle);
 494    if (ret == 0) {
 495        session->handshakeComplete = true;
 496    } else {
 497        if (ret == GNUTLS_E_INTERRUPTED ||
 498            ret == GNUTLS_E_AGAIN) {
 499            ret = 1;
 500        } else {
 501            error_setg(errp, "TLS handshake failed: %s",
 502                       gnutls_strerror(ret));
 503            ret = -1;
 504        }
 505    }
 506
 507    return ret;
 508}
 509
 510
 511QCryptoTLSSessionHandshakeStatus
 512qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *session)
 513{
 514    if (session->handshakeComplete) {
 515        return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
 516    } else if (gnutls_record_get_direction(session->handle) == 0) {
 517        return QCRYPTO_TLS_HANDSHAKE_RECVING;
 518    } else {
 519        return QCRYPTO_TLS_HANDSHAKE_SENDING;
 520    }
 521}
 522
 523
 524int
 525qcrypto_tls_session_get_key_size(QCryptoTLSSession *session,
 526                                 Error **errp)
 527{
 528    gnutls_cipher_algorithm_t cipher;
 529    int ssf;
 530
 531    cipher = gnutls_cipher_get(session->handle);
 532    ssf = gnutls_cipher_get_key_size(cipher);
 533    if (!ssf) {
 534        error_setg(errp, "Cannot get TLS cipher key size");
 535        return -1;
 536    }
 537    return ssf;
 538}
 539
 540
 541char *
 542qcrypto_tls_session_get_peer_name(QCryptoTLSSession *session)
 543{
 544    if (session->peername) {
 545        return g_strdup(session->peername);
 546    }
 547    return NULL;
 548}
 549
 550
 551#else /* ! CONFIG_GNUTLS */
 552
 553
 554QCryptoTLSSession *
 555qcrypto_tls_session_new(QCryptoTLSCreds *creds G_GNUC_UNUSED,
 556                        const char *hostname G_GNUC_UNUSED,
 557                        const char *authzid G_GNUC_UNUSED,
 558                        QCryptoTLSCredsEndpoint endpoint G_GNUC_UNUSED,
 559                        Error **errp)
 560{
 561    error_setg(errp, "TLS requires GNUTLS support");
 562    return NULL;
 563}
 564
 565
 566void
 567qcrypto_tls_session_free(QCryptoTLSSession *sess G_GNUC_UNUSED)
 568{
 569}
 570
 571
 572int
 573qcrypto_tls_session_check_credentials(QCryptoTLSSession *sess G_GNUC_UNUSED,
 574                                      Error **errp)
 575{
 576    error_setg(errp, "TLS requires GNUTLS support");
 577    return -1;
 578}
 579
 580
 581void
 582qcrypto_tls_session_set_callbacks(
 583    QCryptoTLSSession *sess G_GNUC_UNUSED,
 584    QCryptoTLSSessionWriteFunc writeFunc G_GNUC_UNUSED,
 585    QCryptoTLSSessionReadFunc readFunc G_GNUC_UNUSED,
 586    void *opaque G_GNUC_UNUSED)
 587{
 588}
 589
 590
 591ssize_t
 592qcrypto_tls_session_write(QCryptoTLSSession *sess,
 593                          const char *buf,
 594                          size_t len)
 595{
 596    errno = -EIO;
 597    return -1;
 598}
 599
 600
 601ssize_t
 602qcrypto_tls_session_read(QCryptoTLSSession *sess,
 603                         char *buf,
 604                         size_t len)
 605{
 606    errno = -EIO;
 607    return -1;
 608}
 609
 610
 611int
 612qcrypto_tls_session_handshake(QCryptoTLSSession *sess,
 613                              Error **errp)
 614{
 615    error_setg(errp, "TLS requires GNUTLS support");
 616    return -1;
 617}
 618
 619
 620QCryptoTLSSessionHandshakeStatus
 621qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *sess)
 622{
 623    return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
 624}
 625
 626
 627int
 628qcrypto_tls_session_get_key_size(QCryptoTLSSession *sess,
 629                                 Error **errp)
 630{
 631    error_setg(errp, "TLS requires GNUTLS support");
 632    return -1;
 633}
 634
 635
 636char *
 637qcrypto_tls_session_get_peer_name(QCryptoTLSSession *sess)
 638{
 639    return NULL;
 640}
 641
 642#endif
 643