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 "tlscredspriv.h"
  29#include "trace.h"
  30
  31#ifdef CONFIG_GNUTLS
  32
  33
  34#include <gnutls/x509.h>
  35
  36
  37struct QCryptoTLSSession {
  38    QCryptoTLSCreds *creds;
  39    gnutls_session_t handle;
  40    char *hostname;
  41    char *authzid;
  42    bool handshakeComplete;
  43    QCryptoTLSSessionWriteFunc writeFunc;
  44    QCryptoTLSSessionReadFunc readFunc;
  45    void *opaque;
  46    char *peername;
  47};
  48
  49
  50void
  51qcrypto_tls_session_free(QCryptoTLSSession *session)
  52{
  53    if (!session) {
  54        return;
  55    }
  56
  57    gnutls_deinit(session->handle);
  58    g_free(session->hostname);
  59    g_free(session->peername);
  60    g_free(session->authzid);
  61    object_unref(OBJECT(session->creds));
  62    g_free(session);
  63}
  64
  65
  66static ssize_t
  67qcrypto_tls_session_push(void *opaque, const void *buf, size_t len)
  68{
  69    QCryptoTLSSession *session = opaque;
  70
  71    if (!session->writeFunc) {
  72        errno = EIO;
  73        return -1;
  74    };
  75
  76    return session->writeFunc(buf, len, session->opaque);
  77}
  78
  79
  80static ssize_t
  81qcrypto_tls_session_pull(void *opaque, void *buf, size_t len)
  82{
  83    QCryptoTLSSession *session = opaque;
  84
  85    if (!session->readFunc) {
  86        errno = EIO;
  87        return -1;
  88    };
  89
  90    return session->readFunc(buf, len, session->opaque);
  91}
  92
  93#define TLS_PRIORITY_ADDITIONAL_ANON "+ANON-DH"
  94#define TLS_PRIORITY_ADDITIONAL_PSK "+ECDHE-PSK:+DHE-PSK:+PSK"
  95
  96QCryptoTLSSession *
  97qcrypto_tls_session_new(QCryptoTLSCreds *creds,
  98                        const char *hostname,
  99                        const char *authzid,
 100                        QCryptoTLSCredsEndpoint endpoint,
 101                        Error **errp)
 102{
 103    QCryptoTLSSession *session;
 104    int ret;
 105
 106    session = g_new0(QCryptoTLSSession, 1);
 107    trace_qcrypto_tls_session_new(
 108        session, creds, hostname ? hostname : "<none>",
 109        authzid ? authzid : "<none>", endpoint);
 110
 111    if (hostname) {
 112        session->hostname = g_strdup(hostname);
 113    }
 114    if (authzid) {
 115        session->authzid = g_strdup(authzid);
 116    }
 117    session->creds = creds;
 118    object_ref(OBJECT(creds));
 119
 120    if (creds->endpoint != endpoint) {
 121        error_setg(errp, "Credentials endpoint doesn't match session");
 122        goto error;
 123    }
 124
 125    if (endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 126        ret = gnutls_init(&session->handle, GNUTLS_SERVER);
 127    } else {
 128        ret = gnutls_init(&session->handle, GNUTLS_CLIENT);
 129    }
 130    if (ret < 0) {
 131        error_setg(errp, "Cannot initialize TLS session: %s",
 132                   gnutls_strerror(ret));
 133        goto error;
 134    }
 135
 136    if (object_dynamic_cast(OBJECT(creds),
 137                            TYPE_QCRYPTO_TLS_CREDS_ANON)) {
 138        QCryptoTLSCredsAnon *acreds = QCRYPTO_TLS_CREDS_ANON(creds);
 139        char *prio;
 140
 141        if (creds->priority != NULL) {
 142            prio = g_strdup_printf("%s:%s",
 143                                   creds->priority,
 144                                   TLS_PRIORITY_ADDITIONAL_ANON);
 145        } else {
 146            prio = g_strdup(CONFIG_TLS_PRIORITY ":"
 147                            TLS_PRIORITY_ADDITIONAL_ANON);
 148        }
 149
 150        ret = gnutls_priority_set_direct(session->handle, prio, NULL);
 151        if (ret < 0) {
 152            error_setg(errp, "Unable to set TLS session priority %s: %s",
 153                       prio, gnutls_strerror(ret));
 154            g_free(prio);
 155            goto error;
 156        }
 157        g_free(prio);
 158        if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 159            ret = gnutls_credentials_set(session->handle,
 160                                         GNUTLS_CRD_ANON,
 161                                         acreds->data.server);
 162        } else {
 163            ret = gnutls_credentials_set(session->handle,
 164                                         GNUTLS_CRD_ANON,
 165                                         acreds->data.client);
 166        }
 167        if (ret < 0) {
 168            error_setg(errp, "Cannot set session credentials: %s",
 169                       gnutls_strerror(ret));
 170            goto error;
 171        }
 172    } else if (object_dynamic_cast(OBJECT(creds),
 173                                   TYPE_QCRYPTO_TLS_CREDS_PSK)) {
 174        QCryptoTLSCredsPSK *pcreds = QCRYPTO_TLS_CREDS_PSK(creds);
 175        char *prio;
 176
 177        if (creds->priority != NULL) {
 178            prio = g_strdup_printf("%s:%s",
 179                                   creds->priority,
 180                                   TLS_PRIORITY_ADDITIONAL_PSK);
 181        } else {
 182            prio = g_strdup(CONFIG_TLS_PRIORITY ":"
 183                            TLS_PRIORITY_ADDITIONAL_PSK);
 184        }
 185
 186        ret = gnutls_priority_set_direct(session->handle, prio, NULL);
 187        if (ret < 0) {
 188            error_setg(errp, "Unable to set TLS session priority %s: %s",
 189                       prio, gnutls_strerror(ret));
 190            g_free(prio);
 191            goto error;
 192        }
 193        g_free(prio);
 194        if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 195            ret = gnutls_credentials_set(session->handle,
 196                                         GNUTLS_CRD_PSK,
 197                                         pcreds->data.server);
 198        } else {
 199            ret = gnutls_credentials_set(session->handle,
 200                                         GNUTLS_CRD_PSK,
 201                                         pcreds->data.client);
 202        }
 203        if (ret < 0) {
 204            error_setg(errp, "Cannot set session credentials: %s",
 205                       gnutls_strerror(ret));
 206            goto error;
 207        }
 208    } else if (object_dynamic_cast(OBJECT(creds),
 209                                   TYPE_QCRYPTO_TLS_CREDS_X509)) {
 210        QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
 211        const char *prio = creds->priority;
 212        if (!prio) {
 213            prio = CONFIG_TLS_PRIORITY;
 214        }
 215
 216        ret = gnutls_priority_set_direct(session->handle, prio, NULL);
 217        if (ret < 0) {
 218            error_setg(errp, "Cannot set default TLS session priority %s: %s",
 219                       prio, gnutls_strerror(ret));
 220            goto error;
 221        }
 222        ret = gnutls_credentials_set(session->handle,
 223                                     GNUTLS_CRD_CERTIFICATE,
 224                                     tcreds->data);
 225        if (ret < 0) {
 226            error_setg(errp, "Cannot set session credentials: %s",
 227                       gnutls_strerror(ret));
 228            goto error;
 229        }
 230
 231        if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
 232            /* This requests, but does not enforce a client cert.
 233             * The cert checking code later does enforcement */
 234            gnutls_certificate_server_set_request(session->handle,
 235                                                  GNUTLS_CERT_REQUEST);
 236        }
 237    } else {
 238        error_setg(errp, "Unsupported TLS credentials type %s",
 239                   object_get_typename(OBJECT(creds)));
 240        goto error;
 241    }
 242
 243    gnutls_transport_set_ptr(session->handle, session);
 244    gnutls_transport_set_push_function(session->handle,
 245                                       qcrypto_tls_session_push);
 246    gnutls_transport_set_pull_function(session->handle,
 247                                       qcrypto_tls_session_pull);
 248
 249    return session;
 250
 251 error:
 252    qcrypto_tls_session_free(session);
 253    return NULL;
 254}
 255
 256static int
 257qcrypto_tls_session_check_certificate(QCryptoTLSSession *session,
 258                                      Error **errp)
 259{
 260    int ret;
 261    unsigned int status;
 262    const gnutls_datum_t *certs;
 263    unsigned int nCerts, i;
 264    time_t now;
 265    gnutls_x509_crt_t cert = NULL;
 266    Error *err = NULL;
 267
 268    now = time(NULL);
 269    if (now == ((time_t)-1)) {
 270        error_setg_errno(errp, errno, "Cannot get current time");
 271        return -1;
 272    }
 273
 274    ret = gnutls_certificate_verify_peers2(session->handle, &status);
 275    if (ret < 0) {
 276        error_setg(errp, "Verify failed: %s", gnutls_strerror(ret));
 277        return -1;
 278    }
 279
 280    if (status != 0) {
 281        const char *reason = "Invalid certificate";
 282
 283        if (status & GNUTLS_CERT_INVALID) {
 284            reason = "The certificate is not trusted";
 285        }
 286
 287        if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) {
 288            reason = "The certificate hasn't got a known issuer";
 289        }
 290
 291        if (status & GNUTLS_CERT_REVOKED) {
 292            reason = "The certificate has been revoked";
 293        }
 294
 295        if (status & GNUTLS_CERT_INSECURE_ALGORITHM) {
 296            reason = "The certificate uses an insecure algorithm";
 297        }
 298
 299        error_setg(errp, "%s", reason);
 300        return -1;
 301    }
 302
 303    certs = gnutls_certificate_get_peers(session->handle, &nCerts);
 304    if (!certs) {
 305        error_setg(errp, "No certificate peers");
 306        return -1;
 307    }
 308
 309    for (i = 0; i < nCerts; i++) {
 310        ret = gnutls_x509_crt_init(&cert);
 311        if (ret < 0) {
 312            error_setg(errp, "Cannot initialize certificate: %s",
 313                       gnutls_strerror(ret));
 314            return -1;
 315        }
 316
 317        ret = gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER);
 318        if (ret < 0) {
 319            error_setg(errp, "Cannot import certificate: %s",
 320                       gnutls_strerror(ret));
 321            goto error;
 322        }
 323
 324        if (gnutls_x509_crt_get_expiration_time(cert) < now) {
 325            error_setg(errp, "The certificate has expired");
 326            goto error;
 327        }
 328
 329        if (gnutls_x509_crt_get_activation_time(cert) > now) {
 330            error_setg(errp, "The certificate is not yet activated");
 331            goto error;
 332        }
 333
 334        if (gnutls_x509_crt_get_activation_time(cert) > now) {
 335            error_setg(errp, "The certificate is not yet activated");
 336            goto error;
 337        }
 338
 339        if (i == 0) {
 340            size_t dnameSize = 1024;
 341            session->peername = g_malloc(dnameSize);
 342        requery:
 343            ret = gnutls_x509_crt_get_dn(cert, session->peername, &dnameSize);
 344            if (ret < 0) {
 345                if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
 346                    session->peername = g_realloc(session->peername,
 347                                                  dnameSize);
 348                    goto requery;
 349                }
 350                error_setg(errp, "Cannot get client distinguished name: %s",
 351                           gnutls_strerror(ret));
 352                goto error;
 353            }
 354            if (session->authzid) {
 355                bool allow;
 356
 357                allow = qauthz_is_allowed_by_id(session->authzid,
 358                                                session->peername, &err);
 359                if (err) {
 360                    error_propagate(errp, err);
 361                    goto error;
 362                }
 363                if (!allow) {
 364                    error_setg(errp, "TLS x509 authz 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
 390int
 391qcrypto_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
 423void
 424qcrypto_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
 435ssize_t
 436qcrypto_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
 461ssize_t
 462qcrypto_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        case GNUTLS_E_PREMATURE_TERMINATION:
 477            errno = ECONNABORTED;
 478            break;
 479        default:
 480            errno = EIO;
 481            break;
 482        }
 483        ret = -1;
 484    }
 485
 486    return ret;
 487}
 488
 489
 490int
 491qcrypto_tls_session_handshake(QCryptoTLSSession *session,
 492                              Error **errp)
 493{
 494    int ret = gnutls_handshake(session->handle);
 495    if (ret == 0) {
 496        session->handshakeComplete = true;
 497    } else {
 498        if (ret == GNUTLS_E_INTERRUPTED ||
 499            ret == GNUTLS_E_AGAIN) {
 500            ret = 1;
 501        } else {
 502            error_setg(errp, "TLS handshake failed: %s",
 503                       gnutls_strerror(ret));
 504            ret = -1;
 505        }
 506    }
 507
 508    return ret;
 509}
 510
 511
 512QCryptoTLSSessionHandshakeStatus
 513qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *session)
 514{
 515    if (session->handshakeComplete) {
 516        return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
 517    } else if (gnutls_record_get_direction(session->handle) == 0) {
 518        return QCRYPTO_TLS_HANDSHAKE_RECVING;
 519    } else {
 520        return QCRYPTO_TLS_HANDSHAKE_SENDING;
 521    }
 522}
 523
 524
 525int
 526qcrypto_tls_session_get_key_size(QCryptoTLSSession *session,
 527                                 Error **errp)
 528{
 529    gnutls_cipher_algorithm_t cipher;
 530    int ssf;
 531
 532    cipher = gnutls_cipher_get(session->handle);
 533    ssf = gnutls_cipher_get_key_size(cipher);
 534    if (!ssf) {
 535        error_setg(errp, "Cannot get TLS cipher key size");
 536        return -1;
 537    }
 538    return ssf;
 539}
 540
 541
 542char *
 543qcrypto_tls_session_get_peer_name(QCryptoTLSSession *session)
 544{
 545    if (session->peername) {
 546        return g_strdup(session->peername);
 547    }
 548    return NULL;
 549}
 550
 551
 552#else /* ! CONFIG_GNUTLS */
 553
 554
 555QCryptoTLSSession *
 556qcrypto_tls_session_new(QCryptoTLSCreds *creds G_GNUC_UNUSED,
 557                        const char *hostname G_GNUC_UNUSED,
 558                        const char *authzid G_GNUC_UNUSED,
 559                        QCryptoTLSCredsEndpoint endpoint G_GNUC_UNUSED,
 560                        Error **errp)
 561{
 562    error_setg(errp, "TLS requires GNUTLS support");
 563    return NULL;
 564}
 565
 566
 567void
 568qcrypto_tls_session_free(QCryptoTLSSession *sess G_GNUC_UNUSED)
 569{
 570}
 571
 572
 573int
 574qcrypto_tls_session_check_credentials(QCryptoTLSSession *sess G_GNUC_UNUSED,
 575                                      Error **errp)
 576{
 577    error_setg(errp, "TLS requires GNUTLS support");
 578    return -1;
 579}
 580
 581
 582void
 583qcrypto_tls_session_set_callbacks(
 584    QCryptoTLSSession *sess G_GNUC_UNUSED,
 585    QCryptoTLSSessionWriteFunc writeFunc G_GNUC_UNUSED,
 586    QCryptoTLSSessionReadFunc readFunc G_GNUC_UNUSED,
 587    void *opaque G_GNUC_UNUSED)
 588{
 589}
 590
 591
 592ssize_t
 593qcrypto_tls_session_write(QCryptoTLSSession *sess,
 594                          const char *buf,
 595                          size_t len)
 596{
 597    errno = -EIO;
 598    return -1;
 599}
 600
 601
 602ssize_t
 603qcrypto_tls_session_read(QCryptoTLSSession *sess,
 604                         char *buf,
 605                         size_t len)
 606{
 607    errno = -EIO;
 608    return -1;
 609}
 610
 611
 612int
 613qcrypto_tls_session_handshake(QCryptoTLSSession *sess,
 614                              Error **errp)
 615{
 616    error_setg(errp, "TLS requires GNUTLS support");
 617    return -1;
 618}
 619
 620
 621QCryptoTLSSessionHandshakeStatus
 622qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *sess)
 623{
 624    return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
 625}
 626
 627
 628int
 629qcrypto_tls_session_get_key_size(QCryptoTLSSession *sess,
 630                                 Error **errp)
 631{
 632    error_setg(errp, "TLS requires GNUTLS support");
 633    return -1;
 634}
 635
 636
 637char *
 638qcrypto_tls_session_get_peer_name(QCryptoTLSSession *sess)
 639{
 640    return NULL;
 641}
 642
 643#endif
 644