lib/stream-ssl.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "stream-ssl.h"
  19 #include "dhparams.h"
  20 #include <assert.h>
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <inttypes.h>
  24 #include <string.h>
  25 #include <netinet/tcp.h>
  26 #include <openssl/err.h>
  27 #include <openssl/ssl.h>
  28 #include <openssl/x509v3.h>
  29 #include <poll.h>
  30 #include <sys/fcntl.h>
  31 #include <sys/stat.h>
  32 #include <unistd.h>
  33 #include "dynamic-string.h"
  34 #include "leak-checker.h"
  35 #include "ofpbuf.h"
  36 #include "openflow/openflow.h"
  37 #include "packets.h"
  38 #include "poll-loop.h"
  39 #include "socket-util.h"
  40 #include "util.h"
  41 #include "stream-provider.h"
  42 #include "stream.h"
  43 #include "timeval.h"
  44
  45 #include "vlog.h"
  46 #define THIS_MODULE VLM_stream_ssl
  47
  48 /* Active SSL. */
  49
  50 enum ssl_state {
  51     STATE_TCP_CONNECTING,
  52     STATE_SSL_CONNECTING
  53 };
  54
  55 enum session_type {
  56     CLIENT,
  57     SERVER
  58 };
  59
  60 struct ssl_stream
  61 {
  62     struct stream stream;
  63     enum ssl_state state;
  64     int connect_error;
  65     enum session_type type;
  66     int fd;
  67     SSL *ssl;
  68     struct ofpbuf *txbuf;
  69
  70     /* rx_want and tx_want record the result of the last call to SSL_read()
  71      * and SSL_write(), respectively:
  72      *
  73      *    - If the call reported that data needed to be read from the file
  74      *      descriptor, the corresponding member is set to SSL_READING.
  75      *
  76      *    - If the call reported that data needed to be written to the file
  77      *      descriptor, the corresponding member is set to SSL_WRITING.
  78      *
  79      *    - Otherwise, the member is set to SSL_NOTHING, indicating that the
  80      *      call completed successfully (or with an error) and that there is no
  81      *      need to block.
  82      *
  83      * These are needed because there is no way to ask OpenSSL what a data read
  84      * or write would require without giving it a buffer to receive into or
  85      * data to send, respectively.  (Note that the SSL_want() status is
  86      * overwritten by each SSL_read() or SSL_write() call, so we can't rely on
  87      * its value.)
  88      *
  89      * A single call to SSL_read() or SSL_write() can perform both reading
  90      * and writing and thus invalidate not one of these values but actually
  91      * both.  Consider this situation, for example:
  92      *
  93      *    - SSL_write() blocks on a read, so tx_want gets SSL_READING.
  94      *
  95      *    - SSL_read() laters succeeds reading from 'fd' and clears out the
  96      *      whole receive buffer, so rx_want gets SSL_READING.
  97      *
  98      *    - Client calls stream_wait(STREAM_RECV) and stream_wait(STREAM_SEND)
  99      *      and blocks.
 100      *
 101      *    - Now we're stuck blocking until the peer sends us data, even though
 102      *      SSL_write() could now succeed, which could easily be a deadlock
 103      *      condition.
 104      *
 105      * On the other hand, we can't reset both tx_want and rx_want on every call
 106      * to SSL_read() or SSL_write(), because that would produce livelock,
 107      * e.g. in this situation:
 108      *
 109      *    - SSL_write() blocks, so tx_want gets SSL_READING or SSL_WRITING.
 110      *
 111      *    - SSL_read() blocks, so rx_want gets SSL_READING or SSL_WRITING,
 112      *      but tx_want gets reset to SSL_NOTHING.
 113      *
 114      *    - Client calls stream_wait(STREAM_RECV) and stream_wait(STREAM_SEND)
 115      *      and blocks.
 116      *
 117      *    - Client wakes up immediately since SSL_NOTHING in tx_want indicates
 118      *      that no blocking is necessary.
 119      *
 120      * The solution we adopt here is to set tx_want to SSL_NOTHING after
 121      * calling SSL_read() only if the SSL state of the connection changed,
 122      * which indicates that an SSL-level renegotiation made some progress, and
 123      * similarly for rx_want and SSL_write().  This prevents both the
 124      * deadlock and livelock situations above.
 125      */
 126     int rx_want, tx_want;
 127 };
 128
 129 /* SSL context created by ssl_init(). */
 130 static SSL_CTX *ctx;
 131
 132 struct ssl_config_file {
 133     bool read;                  /* Whether the file was successfully read. */
 134     char *file_name;            /* Configured file name, if any. */
 135     struct timespec mtime;      /* File mtime as of last time we read it. */
 136 };
 137
 138 /* SSL configuration files. */
 139 static struct ssl_config_file private_key;
 140 static struct ssl_config_file certificate;
 141 static struct ssl_config_file ca_cert;
 142
 143 /* Ordinarily, the SSL client and server verify each other's certificates using
 144  * a CA certificate.  Setting this to false disables this behavior.  (This is a
 145  * security risk.) */
 146 static bool verify_peer_cert = true;
 147
 148 /* Ordinarily, we require a CA certificate for the peer to be locally
 149  * available.  We can, however, bootstrap the CA certificate from the peer at
 150  * the beginning of our first connection then use that certificate on all
 151  * subsequent connections, saving it to a file for use in future runs also.  In
 152  * this case, 'bootstrap_ca_cert' is true. */
 153 static bool bootstrap_ca_cert;
 154
 155 /* Who knows what can trigger various SSL errors, so let's throttle them down
 156  * quite a bit. */
 157 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 25);
 158
 159 static int ssl_init(void);
 160 static int do_ssl_init(void);
 161 static bool ssl_wants_io(int ssl_error);
 162 static void ssl_close(struct stream *);
 163 static void ssl_clear_txbuf(struct ssl_stream *);
 164 static int interpret_ssl_error(const char *function, int ret, int error,
 165                                int *want);
 166 static DH *tmp_dh_callback(SSL *ssl, int is_export OVS_UNUSED, int keylength);
 167 static void log_ca_cert(const char *file_name, X509 *cert);
 168 static void stream_ssl_set_ca_cert_file__(const char *file_name,
 169                                           bool bootstrap);
 170
 171 static short int
 172 want_to_poll_events(int want)
 173 {
 174     switch (want) {
 175     case SSL_NOTHING:
 176         NOT_REACHED();
 177
 178     case SSL_READING:
 179         return POLLIN;
 180
 181     case SSL_WRITING:
 182         return POLLOUT;
 183
 184     default:
 185         NOT_REACHED();
 186     }
 187 }
 188
 189 static int
 190 new_ssl_stream(const char *name, int fd, enum session_type type,
 191               enum ssl_state state, const struct sockaddr_in *remote,
 192               struct stream **streamp)
 193 {
 194     struct sockaddr_in local;
 195     socklen_t local_len = sizeof local;
 196     struct ssl_stream *sslv;
 197     SSL *ssl = NULL;
 198     int on = 1;
 199     int retval;
 200
 201     /* Check for all the needful configuration. */
 202     retval = 0;
 203     if (!private_key.read) {
 204         VLOG_ERR("Private key must be configured to use SSL");
 205         retval = ENOPROTOOPT;
 206     }
 207     if (!certificate.read) {
 208         VLOG_ERR("Certificate must be configured to use SSL");
 209         retval = ENOPROTOOPT;
 210     }
 211     if (!ca_cert.read && verify_peer_cert && !bootstrap_ca_cert) {
 212         VLOG_ERR("CA certificate must be configured to use SSL");
 213         retval = ENOPROTOOPT;
 214     }
 215     if (!SSL_CTX_check_private_key(ctx)) {
 216         VLOG_ERR("Private key does not match certificate public key: %s",
 217                  ERR_error_string(ERR_get_error(), NULL));
 218         retval = ENOPROTOOPT;
 219     }
 220     if (retval) {
 221         goto error;
 222     }
 223
 224     /* Get the local IP and port information */
 225     retval = getsockname(fd, (struct sockaddr *) &local, &local_len);
 226     if (retval) {
 227         memset(&local, 0, sizeof local);
 228     }
 229
 230     /* Disable Nagle. */
 231     retval = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof on);
 232     if (retval) {
 233         VLOG_ERR("%s: setsockopt(TCP_NODELAY): %s", name, strerror(errno));
 234         retval = errno;
 235         goto error;
 236     }
 237
 238     /* Create and configure OpenSSL stream. */
 239     ssl = SSL_new(ctx);
 240     if (ssl == NULL) {
 241         VLOG_ERR("SSL_new: %s", ERR_error_string(ERR_get_error(), NULL));
 242         retval = ENOPROTOOPT;
 243         goto error;
 244     }
 245     if (SSL_set_fd(ssl, fd) == 0) {
 246         VLOG_ERR("SSL_set_fd: %s", ERR_error_string(ERR_get_error(), NULL));
 247         retval = ENOPROTOOPT;
 248         goto error;
 249     }
 250     if (!verify_peer_cert || (bootstrap_ca_cert && type == CLIENT)) {
 251         SSL_set_verify(ssl, SSL_VERIFY_NONE, NULL);
 252     }
 253
 254     /* Create and return the ssl_stream. */
 255     sslv = xmalloc(sizeof *sslv);
 256     stream_init(&sslv->stream, &ssl_stream_class, EAGAIN, name);
 257     stream_set_remote_ip(&sslv->stream, remote->sin_addr.s_addr);
 258     stream_set_remote_port(&sslv->stream, remote->sin_port);
 259     stream_set_local_ip(&sslv->stream, local.sin_addr.s_addr);
 260     stream_set_local_port(&sslv->stream, local.sin_port);
 261     sslv->state = state;
 262     sslv->type = type;
 263     sslv->fd = fd;
 264     sslv->ssl = ssl;
 265     sslv->txbuf = NULL;
 266     sslv->rx_want = sslv->tx_want = SSL_NOTHING;
 267     *streamp = &sslv->stream;
 268     return 0;
 269
 270 error:
 271     if (ssl) {
 272         SSL_free(ssl);
 273     }
 274     close(fd);
 275     return retval;
 276 }
 277
 278 static struct ssl_stream *
 279 ssl_stream_cast(struct stream *stream)
 280 {
 281     stream_assert_class(stream, &ssl_stream_class);
 282     return CONTAINER_OF(stream, struct ssl_stream, stream);
 283 }
 284
 285 static int
 286 ssl_open(const char *name, char *suffix, struct stream **streamp)
 287 {
 288     struct sockaddr_in sin;
 289     int error, fd;
 290
 291     error = ssl_init();
 292     if (error) {
 293         return error;
 294     }
 295
 296     error = inet_open_active(SOCK_STREAM, suffix, OFP_SSL_PORT, &sin, &fd);
 297     if (fd >= 0) {
 298         int state = error ? STATE_TCP_CONNECTING : STATE_SSL_CONNECTING;
 299         return new_ssl_stream(name, fd, CLIENT, state, &sin, streamp);
 300     } else {
 301         VLOG_ERR("%s: connect: %s", name, strerror(error));
 302         return error;
 303     }
 304 }
 305
 306 static int
 307 do_ca_cert_bootstrap(struct stream *stream)
 308 {
 309     struct ssl_stream *sslv = ssl_stream_cast(stream);
 310     STACK_OF(X509) *chain;
 311     X509 *cert;
 312     FILE *file;
 313     int error;
 314     int fd;
 315
 316     chain = SSL_get_peer_cert_chain(sslv->ssl);
 317     if (!chain || !sk_X509_num(chain)) {
 318         VLOG_ERR("could not bootstrap CA cert: no certificate presented by "
 319                  "peer");
 320         return EPROTO;
 321     }
 322     cert = sk_X509_value(chain, sk_X509_num(chain) - 1);
 323
 324     /* Check that 'cert' is self-signed.  Otherwise it is not a CA
 325      * certificate and we should not attempt to use it as one. */
 326     error = X509_check_issued(cert, cert);
 327     if (error) {
 328         VLOG_ERR("could not bootstrap CA cert: obtained certificate is "
 329                  "not self-signed (%s)",
 330                  X509_verify_cert_error_string(error));
 331         if (sk_X509_num(chain) < 2) {
 332             VLOG_ERR("only one certificate was received, so probably the peer "
 333                      "is not configured to send its CA certificate");
 334         }
 335         return EPROTO;
 336     }
 337
 338     fd = open(ca_cert.file_name, O_CREAT | O_EXCL | O_WRONLY, 0444);
 339     if (fd < 0) {
 340         if (errno == EEXIST) {
 341             VLOG_INFO("reading CA cert %s created by another process",
 342                       ca_cert.file_name);
 343             stream_ssl_set_ca_cert_file(ca_cert.file_name, true);
 344             return EPROTO;
 345         } else {
 346             VLOG_ERR("could not bootstrap CA cert: creating %s failed: %s",
 347                      ca_cert.file_name, strerror(errno));
 348             return errno;
 349         }
 350     }
 351
 352     file = fdopen(fd, "w");
 353     if (!file) {
 354         int error = errno;
 355         VLOG_ERR("could not bootstrap CA cert: fdopen failed: %s",
 356                  strerror(error));
 357         unlink(ca_cert.file_name);
 358         return error;
 359     }
 360
 361     if (!PEM_write_X509(file, cert)) {
 362         VLOG_ERR("could not bootstrap CA cert: PEM_write_X509 to %s failed: "
 363                  "%s", ca_cert.file_name,
 364                  ERR_error_string(ERR_get_error(), NULL));
 365         fclose(file);
 366         unlink(ca_cert.file_name);
 367         return EIO;
 368     }
 369
 370     if (fclose(file)) {
 371         int error = errno;
 372         VLOG_ERR("could not bootstrap CA cert: writing %s failed: %s",
 373                  ca_cert.file_name, strerror(error));
 374         unlink(ca_cert.file_name);
 375         return error;
 376     }
 377
 378     VLOG_INFO("successfully bootstrapped CA cert to %s", ca_cert.file_name);
 379     log_ca_cert(ca_cert.file_name, cert);
 380     bootstrap_ca_cert = false;
 381     ca_cert.read = true;
 382
 383     /* SSL_CTX_add_client_CA makes a copy of cert's relevant data. */
 384     SSL_CTX_add_client_CA(ctx, cert);
 385
 386     /* SSL_CTX_use_certificate() takes ownership of the certificate passed in.
 387      * 'cert' is owned by sslv->ssl, so we need to duplicate it. */
 388     cert = X509_dup(cert);
 389     if (!cert) {
 390         out_of_memory();
 391     }
 392     if (SSL_CTX_load_verify_locations(ctx, ca_cert.file_name, NULL) != 1) {
 393         VLOG_ERR("SSL_CTX_load_verify_locations: %s",
 394                  ERR_error_string(ERR_get_error(), NULL));
 395         return EPROTO;
 396     }
 397     VLOG_INFO("killing successful connection to retry using CA cert");
 398     return EPROTO;
 399 }
 400
 401 static int
 402 ssl_connect(struct stream *stream)
 403 {
 404     struct ssl_stream *sslv = ssl_stream_cast(stream);
 405     int retval;
 406
 407     switch (sslv->state) {
 408     case STATE_TCP_CONNECTING:
 409         retval = check_connection_completion(sslv->fd);
 410         if (retval) {
 411             return retval;
 412         }
 413         sslv->state = STATE_SSL_CONNECTING;
 414         /* Fall through. */
 415
 416     case STATE_SSL_CONNECTING:
 417         retval = (sslv->type == CLIENT
 418                    ? SSL_connect(sslv->ssl) : SSL_accept(sslv->ssl));
 419         if (retval != 1) {
 420             int error = SSL_get_error(sslv->ssl, retval);
 421             if (retval < 0 && ssl_wants_io(error)) {
 422                 return EAGAIN;
 423             } else {
 424                 int unused;
 425                 interpret_ssl_error((sslv->type == CLIENT ? "SSL_connect"
 426                                      : "SSL_accept"), retval, error, &unused);
 427                 shutdown(sslv->fd, SHUT_RDWR);
 428                 return EPROTO;
 429             }
 430         } else if (bootstrap_ca_cert) {
 431             return do_ca_cert_bootstrap(stream);
 432         } else if (verify_peer_cert
 433                    && ((SSL_get_verify_mode(sslv->ssl)
 434                        & (SSL_VERIFY_NONE | SSL_VERIFY_PEER))
 435                        != SSL_VERIFY_PEER)) {
 436             /* Two or more SSL connections completed at the same time while we
 437              * were in bootstrap mode.  Only one of these can finish the
 438              * bootstrap successfully.  The other one(s) must be rejected
 439              * because they were not verified against the bootstrapped CA
 440              * certificate.  (Alternatively we could verify them against the CA
 441              * certificate, but that's more trouble than it's worth.  These
 442              * connections will succeed the next time they retry, assuming that
 443              * they have a certificate against the correct CA.) */
 444             VLOG_ERR("rejecting SSL connection during bootstrap race window");
 445             return EPROTO;
 446         } else {
 447             return 0;
 448         }
 449     }
 450
 451     NOT_REACHED();
 452 }
 453
 454 static void
 455 ssl_close(struct stream *stream)
 456 {
 457     struct ssl_stream *sslv = ssl_stream_cast(stream);
 458     ssl_clear_txbuf(sslv);
 459
 460     /* Attempt clean shutdown of the SSL connection.  This will work most of
 461      * the time, as long as the kernel send buffer has some free space and the
 462      * SSL connection isn't renegotiating, etc.  That has to be good enough,
 463      * since we don't have any way to continue the close operation in the
 464      * background. */
 465     SSL_shutdown(sslv->ssl);
 466
 467     SSL_free(sslv->ssl);
 468     close(sslv->fd);
 469     free(sslv);
 470 }
 471
 472 static int
 473 interpret_ssl_error(const char *function, int ret, int error,
 474                     int *want)
 475 {
 476     *want = SSL_NOTHING;
 477
 478     switch (error) {
 479     case SSL_ERROR_NONE:
 480         VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_NONE", function);
 481         break;
 482
 483     case SSL_ERROR_ZERO_RETURN:
 484         VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_ZERO_RETURN", function);
 485         break;
 486
 487     case SSL_ERROR_WANT_READ:
 488         *want = SSL_READING;
 489         return EAGAIN;
 490
 491     case SSL_ERROR_WANT_WRITE:
 492         *want = SSL_WRITING;
 493         return EAGAIN;
 494
 495     case SSL_ERROR_WANT_CONNECT:
 496         VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_CONNECT", function);
 497         break;
 498
 499     case SSL_ERROR_WANT_ACCEPT:
 500         VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_ACCEPT", function);
 501         break;
 502
 503     case SSL_ERROR_WANT_X509_LOOKUP:
 504         VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_X509_LOOKUP",
 505                     function);
 506         break;
 507
 508     case SSL_ERROR_SYSCALL: {
 509         int queued_error = ERR_get_error();
 510         if (queued_error == 0) {
 511             if (ret < 0) {
 512                 int status = errno;
 513                 VLOG_WARN_RL(&rl, "%s: system error (%s)",
 514                              function, strerror(status));
 515                 return status;
 516             } else {
 517                 VLOG_WARN_RL(&rl, "%s: unexpected SSL connection close",
 518                              function);
 519                 return EPROTO;
 520             }
 521         } else {
 522             VLOG_WARN_RL(&rl, "%s: %s",
 523                          function, ERR_error_string(queued_error, NULL));
 524             break;
 525         }
 526     }
 527
 528     case SSL_ERROR_SSL: {
 529         int queued_error = ERR_get_error();
 530         if (queued_error != 0) {
 531             VLOG_WARN_RL(&rl, "%s: %s",
 532                          function, ERR_error_string(queued_error, NULL));
 533         } else {
 534             VLOG_ERR_RL(&rl, "%s: SSL_ERROR_SSL without queued error",
 535                         function);
 536         }
 537         break;
 538     }
 539
 540     default:
 541         VLOG_ERR_RL(&rl, "%s: bad SSL error code %d", function, error);
 542         break;
 543     }
 544     return EIO;
 545 }
 546
 547 static ssize_t
 548 ssl_recv(struct stream *stream, void *buffer, size_t n)
 549 {
 550     struct ssl_stream *sslv = ssl_stream_cast(stream);
 551     int old_state;
 552     ssize_t ret;
 553
 554     /* Behavior of zero-byte SSL_read is poorly defined. */
 555     assert(n > 0);
 556
 557     old_state = SSL_get_state(sslv->ssl);
 558     ret = SSL_read(sslv->ssl, buffer, n);
 559     if (old_state != SSL_get_state(sslv->ssl)) {
 560         sslv->tx_want = SSL_NOTHING;
 561     }
 562     sslv->rx_want = SSL_NOTHING;
 563
 564     if (ret > 0) {
 565         return ret;
 566     } else {
 567         int error = SSL_get_error(sslv->ssl, ret);
 568         if (error == SSL_ERROR_ZERO_RETURN) {
 569             return 0;
 570         } else {
 571             return -interpret_ssl_error("SSL_read", ret, error,
 572                                         &sslv->rx_want);
 573         }
 574     }
 575 }
 576
 577 static void
 578 ssl_clear_txbuf(struct ssl_stream *sslv)
 579 {
 580     ofpbuf_delete(sslv->txbuf);
 581     sslv->txbuf = NULL;
 582 }
 583
 584 static int
 585 ssl_do_tx(struct stream *stream)
 586 {
 587     struct ssl_stream *sslv = ssl_stream_cast(stream);
 588
 589     for (;;) {
 590         int old_state = SSL_get_state(sslv->ssl);
 591         int ret = SSL_write(sslv->ssl, sslv->txbuf->data, sslv->txbuf->size);
 592         if (old_state != SSL_get_state(sslv->ssl)) {
 593             sslv->rx_want = SSL_NOTHING;
 594         }
 595         sslv->tx_want = SSL_NOTHING;
 596         if (ret > 0) {
 597             ofpbuf_pull(sslv->txbuf, ret);
 598             if (sslv->txbuf->size == 0) {
 599                 return 0;
 600             }
 601         } else {
 602             int ssl_error = SSL_get_error(sslv->ssl, ret);
 603             if (ssl_error == SSL_ERROR_ZERO_RETURN) {
 604                 VLOG_WARN_RL(&rl, "SSL_write: connection closed");
 605                 return EPIPE;
 606             } else {
 607                 return interpret_ssl_error("SSL_write", ret, ssl_error,
 608                                            &sslv->tx_want);
 609             }
 610         }
 611     }
 612 }
 613
 614 static ssize_t
 615 ssl_send(struct stream *stream, const void *buffer, size_t n)
 616 {
 617     struct ssl_stream *sslv = ssl_stream_cast(stream);
 618
 619     if (sslv->txbuf) {
 620         return -EAGAIN;
 621     } else {
 622         int error;
 623
 624         sslv->txbuf = ofpbuf_clone_data(buffer, n);
 625         error = ssl_do_tx(stream);
 626         switch (error) {
 627         case 0:
 628             ssl_clear_txbuf(sslv);
 629             return n;
 630         case EAGAIN:
 631             leak_checker_claim(buffer);
 632             return n;
 633         default:
 634             sslv->txbuf = NULL;
 635             return -error;
 636         }
 637     }
 638 }
 639
 640 static void
 641 ssl_run(struct stream *stream)
 642 {
 643     struct ssl_stream *sslv = ssl_stream_cast(stream);
 644
 645     if (sslv->txbuf && ssl_do_tx(stream) != EAGAIN) {
 646         ssl_clear_txbuf(sslv);
 647     }
 648 }
 649
 650 static void
 651 ssl_run_wait(struct stream *stream)
 652 {
 653     struct ssl_stream *sslv = ssl_stream_cast(stream);
 654
 655     if (sslv->tx_want != SSL_NOTHING) {
 656         poll_fd_wait(sslv->fd, want_to_poll_events(sslv->tx_want));
 657     }
 658 }
 659
 660 static void
 661 ssl_wait(struct stream *stream, enum stream_wait_type wait)
 662 {
 663     struct ssl_stream *sslv = ssl_stream_cast(stream);
 664
 665     switch (wait) {
 666     case STREAM_CONNECT:
 667         if (stream_connect(stream) != EAGAIN) {
 668             poll_immediate_wake();
 669         } else {
 670             switch (sslv->state) {
 671             case STATE_TCP_CONNECTING:
 672                 poll_fd_wait(sslv->fd, POLLOUT);
 673                 break;
 674
 675             case STATE_SSL_CONNECTING:
 676                 /* ssl_connect() called SSL_accept() or SSL_connect(), which
 677                  * set up the status that we test here. */
 678                 poll_fd_wait(sslv->fd,
 679                              want_to_poll_events(SSL_want(sslv->ssl)));
 680                 break;
 681
 682             default:
 683                 NOT_REACHED();
 684             }
 685         }
 686         break;
 687
 688     case STREAM_RECV:
 689         if (sslv->rx_want != SSL_NOTHING) {
 690             poll_fd_wait(sslv->fd, want_to_poll_events(sslv->rx_want));
 691         } else {
 692             poll_immediate_wake();
 693         }
 694         break;
 695
 696     case STREAM_SEND:
 697         if (!sslv->txbuf) {
 698             /* We have room in our tx queue. */
 699             poll_immediate_wake();
 700         } else {
 701             /* stream_run_wait() will do the right thing; don't bother with
 702              * redundancy. */
 703         }
 704         break;
 705
 706     default:
 707         NOT_REACHED();
 708     }
 709 }
 710
 711 struct stream_class ssl_stream_class = {
 712     "ssl",                      /* name */
 713     ssl_open,                   /* open */
 714     ssl_close,                  /* close */
 715     ssl_connect,                /* connect */
 716     ssl_recv,                   /* recv */
 717     ssl_send,                   /* send */
 718     ssl_run,                    /* run */
 719     ssl_run_wait,               /* run_wait */
 720     ssl_wait,                   /* wait */
 721 };
 722 \f
 723 /* Passive SSL. */
 724
 725 struct pssl_pstream
 726 {
 727     struct pstream pstream;
 728     int fd;
 729 };
 730
 731 struct pstream_class pssl_pstream_class;
 732
 733 static struct pssl_pstream *
 734 pssl_pstream_cast(struct pstream *pstream)
 735 {
 736     pstream_assert_class(pstream, &pssl_pstream_class);
 737     return CONTAINER_OF(pstream, struct pssl_pstream, pstream);
 738 }
 739
 740 static int
 741 pssl_open(const char *name OVS_UNUSED, char *suffix, struct pstream **pstreamp)
 742 {
 743     struct pssl_pstream *pssl;
 744     struct sockaddr_in sin;
 745     char bound_name[128];
 746     int retval;
 747     int fd;
 748
 749     retval = ssl_init();
 750     if (retval) {
 751         return retval;
 752     }
 753
 754     fd = inet_open_passive(SOCK_STREAM, suffix, OFP_SSL_PORT, &sin);
 755     if (fd < 0) {
 756         return -fd;
 757     }
 758     sprintf(bound_name, "pssl:%"PRIu16":"IP_FMT,
 759             ntohs(sin.sin_port), IP_ARGS(&sin.sin_addr.s_addr));
 760
 761     pssl = xmalloc(sizeof *pssl);
 762     pstream_init(&pssl->pstream, &pssl_pstream_class, bound_name);
 763     pssl->fd = fd;
 764     *pstreamp = &pssl->pstream;
 765     return 0;
 766 }
 767
 768 static void
 769 pssl_close(struct pstream *pstream)
 770 {
 771     struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
 772     close(pssl->fd);
 773     free(pssl);
 774 }
 775
 776 static int
 777 pssl_accept(struct pstream *pstream, struct stream **new_streamp)
 778 {
 779     struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
 780     struct sockaddr_in sin;
 781     socklen_t sin_len = sizeof sin;
 782     char name[128];
 783     int new_fd;
 784     int error;
 785
 786     new_fd = accept(pssl->fd, &sin, &sin_len);
 787     if (new_fd < 0) {
 788         int error = errno;
 789         if (error != EAGAIN) {
 790             VLOG_DBG_RL(&rl, "accept: %s", strerror(error));
 791         }
 792         return error;
 793     }
 794
 795     error = set_nonblocking(new_fd);
 796     if (error) {
 797         close(new_fd);
 798         return error;
 799     }
 800
 801     sprintf(name, "ssl:"IP_FMT, IP_ARGS(&sin.sin_addr));
 802     if (sin.sin_port != htons(OFP_SSL_PORT)) {
 803         sprintf(strchr(name, '\0'), ":%"PRIu16, ntohs(sin.sin_port));
 804     }
 805     return new_ssl_stream(name, new_fd, SERVER, STATE_SSL_CONNECTING, &sin,
 806                          new_streamp);
 807 }
 808
 809 static void
 810 pssl_wait(struct pstream *pstream)
 811 {
 812     struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
 813     poll_fd_wait(pssl->fd, POLLIN);
 814 }
 815
 816 struct pstream_class pssl_pstream_class = {
 817     "pssl",
 818     pssl_open,
 819     pssl_close,
 820     pssl_accept,
 821     pssl_wait,
 822 };
 823 \f
 824 /*
 825  * Returns true if OpenSSL error is WANT_READ or WANT_WRITE, indicating that
 826  * OpenSSL is requesting that we call it back when the socket is ready for read
 827  * or writing, respectively.
 828  */
 829 static bool
 830 ssl_wants_io(int ssl_error)
 831 {
 832     return (ssl_error == SSL_ERROR_WANT_WRITE
 833             || ssl_error == SSL_ERROR_WANT_READ);
 834 }
 835
 836 static int
 837 ssl_init(void)
 838 {
 839     static int init_status = -1;
 840     if (init_status < 0) {
 841         init_status = do_ssl_init();
 842         assert(init_status >= 0);
 843     }
 844     return init_status;
 845 }
 846
 847 static int
 848 do_ssl_init(void)
 849 {
 850     SSL_METHOD *method;
 851
 852     SSL_library_init();
 853     SSL_load_error_strings();
 854
 855     method = TLSv1_method();
 856     if (method == NULL) {
 857         VLOG_ERR("TLSv1_method: %s", ERR_error_string(ERR_get_error(), NULL));
 858         return ENOPROTOOPT;
 859     }
 860
 861     ctx = SSL_CTX_new(method);
 862     if (ctx == NULL) {
 863         VLOG_ERR("SSL_CTX_new: %s", ERR_error_string(ERR_get_error(), NULL));
 864         return ENOPROTOOPT;
 865     }
 866     SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
 867     SSL_CTX_set_tmp_dh_callback(ctx, tmp_dh_callback);
 868     SSL_CTX_set_mode(ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
 869     SSL_CTX_set_mode(ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
 870     SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
 871                        NULL);
 872
 873     return 0;
 874 }
 875
 876 static DH *
 877 tmp_dh_callback(SSL *ssl OVS_UNUSED, int is_export OVS_UNUSED, int keylength)
 878 {
 879     struct dh {
 880         int keylength;
 881         DH *dh;
 882         DH *(*constructor)(void);
 883     };
 884
 885     static struct dh dh_table[] = {
 886         {1024, NULL, get_dh1024},
 887         {2048, NULL, get_dh2048},
 888         {4096, NULL, get_dh4096},
 889     };
 890
 891     struct dh *dh;
 892
 893     for (dh = dh_table; dh < &dh_table[ARRAY_SIZE(dh_table)]; dh++) {
 894         if (dh->keylength == keylength) {
 895             if (!dh->dh) {
 896                 dh->dh = dh->constructor();
 897                 if (!dh->dh) {
 898                     ovs_fatal(ENOMEM, "out of memory constructing "
 899                               "Diffie-Hellman parameters");
 900                 }
 901             }
 902             return dh->dh;
 903         }
 904     }
 905     VLOG_ERR_RL(&rl, "no Diffie-Hellman parameters for key length %d",
 906                 keylength);
 907     return NULL;
 908 }
 909
 910 /* Returns true if SSL is at least partially configured. */
 911 bool
 912 stream_ssl_is_configured(void)
 913 {
 914     return private_key.file_name || certificate.file_name || ca_cert.file_name;
 915 }
 916
 917 static bool
 918 update_ssl_config(struct ssl_config_file *config, const char *file_name)
 919 {
 920     struct timespec mtime;
 921
 922     if (ssl_init() || !file_name) {
 923         return false;
 924     }
 925
 926     /* If the file name hasn't changed and neither has the file contents, stop
 927      * here. */
 928     get_mtime(file_name, &mtime);
 929     if (config->file_name
 930         && !strcmp(config->file_name, file_name)
 931         && mtime.tv_sec == config->mtime.tv_sec
 932         && mtime.tv_nsec == config->mtime.tv_nsec) {
 933         return false;
 934     }
 935
 936     /* Update 'config'. */
 937     config->mtime = mtime;
 938     if (file_name != config->file_name) {
 939         free(config->file_name);
 940         config->file_name = xstrdup(file_name);
 941     }
 942     return true;
 943 }
 944
 945 void
 946 stream_ssl_set_private_key_file(const char *file_name)
 947 {
 948     if (!update_ssl_config(&private_key, file_name)) {
 949         return;
 950     }
 951     if (SSL_CTX_use_PrivateKey_file(ctx, file_name, SSL_FILETYPE_PEM) != 1) {
 952         VLOG_ERR("SSL_use_PrivateKey_file: %s",
 953                  ERR_error_string(ERR_get_error(), NULL));
 954         return;
 955     }
 956     private_key.read = true;
 957 }
 958
 959 void
 960 stream_ssl_set_certificate_file(const char *file_name)
 961 {
 962     if (!update_ssl_config(&certificate, file_name)) {
 963         return;
 964     }
 965     if (SSL_CTX_use_certificate_chain_file(ctx, file_name) != 1) {
 966         VLOG_ERR("SSL_use_certificate_file: %s",
 967                  ERR_error_string(ERR_get_error(), NULL));
 968         return;
 969     }
 970     certificate.read = true;
 971 }
 972
 973 /* Reads the X509 certificate or certificates in file 'file_name'.  On success,
 974  * stores the address of the first element in an array of pointers to
 975  * certificates in '*certs' and the number of certificates in the array in
 976  * '*n_certs', and returns 0.  On failure, stores a null pointer in '*certs', 0
 977  * in '*n_certs', and returns a positive errno value.
 978  *
 979  * The caller is responsible for freeing '*certs'. */
 980 static int
 981 read_cert_file(const char *file_name, X509 ***certs, size_t *n_certs)
 982 {
 983     FILE *file;
 984     size_t allocated_certs = 0;
 985
 986     *certs = NULL;
 987     *n_certs = 0;
 988
 989     file = fopen(file_name, "r");
 990     if (!file) {
 991         VLOG_ERR("failed to open %s for reading: %s",
 992                  file_name, strerror(errno));
 993         return errno;
 994     }
 995
 996     for (;;) {
 997         X509 *certificate;
 998         int c;
 999
1000         /* Read certificate from file. */
1001         certificate = PEM_read_X509(file, NULL, NULL, NULL);
1002         if (!certificate) {
1003             size_t i;
1004
1005             VLOG_ERR("PEM_read_X509 failed reading %s: %s",
1006                      file_name, ERR_error_string(ERR_get_error(), NULL));
1007             for (i = 0; i < *n_certs; i++) {
1008                 X509_free((*certs)[i]);
1009             }
1010             free(*certs);
1011             *certs = NULL;
1012             *n_certs = 0;
1013             return EIO;
1014         }
1015
1016         /* Add certificate to array. */
1017         if (*n_certs >= allocated_certs) {
1018             *certs = x2nrealloc(*certs, &allocated_certs, sizeof **certs);
1019         }
1020         (*certs)[(*n_certs)++] = certificate;
1021
1022         /* Are there additional certificates in the file? */
1023         do {
1024             c = getc(file);
1025         } while (isspace(c));
1026         if (c == EOF) {
1027             break;
1028         }
1029         ungetc(c, file);
1030     }
1031     fclose(file);
1032     return 0;
1033 }
1034
1035
1036 /* Sets 'file_name' as the name of a file containing one or more X509
1037  * certificates to send to the peer.  Typical use in OpenFlow is to send the CA
1038  * certificate to the peer, which enables a switch to pick up the controller's
1039  * CA certificate on its first connection. */
1040 void
1041 stream_ssl_set_peer_ca_cert_file(const char *file_name)
1042 {
1043     X509 **certs;
1044     size_t n_certs;
1045     size_t i;
1046
1047     if (ssl_init()) {
1048         return;
1049     }
1050
1051     if (!read_cert_file(file_name, &certs, &n_certs)) {
1052         for (i = 0; i < n_certs; i++) {
1053             if (SSL_CTX_add_extra_chain_cert(ctx, certs[i]) != 1) {
1054                 VLOG_ERR("SSL_CTX_add_extra_chain_cert: %s",
1055                          ERR_error_string(ERR_get_error(), NULL));
1056             }
1057         }
1058         free(certs);
1059     }
1060 }
1061
1062 /* Logs fingerprint of CA certificate 'cert' obtained from 'file_name'. */
1063 static void
1064 log_ca_cert(const char *file_name, X509 *cert)
1065 {
1066     unsigned char digest[EVP_MAX_MD_SIZE];
1067     unsigned int n_bytes;
1068     struct ds fp;
1069     char *subject;
1070
1071     ds_init(&fp);
1072     if (!X509_digest(cert, EVP_sha1(), digest, &n_bytes)) {
1073         ds_put_cstr(&fp, "<out of memory>");
1074     } else {
1075         unsigned int i;
1076         for (i = 0; i < n_bytes; i++) {
1077             if (i) {
1078                 ds_put_char(&fp, ':');
1079             }
1080             ds_put_format(&fp, "%02hhx", digest[i]);
1081         }
1082     }
1083     subject = X509_NAME_oneline(X509_get_subject_name(cert), NULL, 0);
1084     VLOG_INFO("Trusting CA cert from %s (%s) (fingerprint %s)", file_name,
1085               subject ? subject : "<out of memory>", ds_cstr(&fp));
1086     free(subject);
1087     ds_destroy(&fp);
1088 }
1089
1090 static void
1091 stream_ssl_set_ca_cert_file__(const char *file_name, bool bootstrap)
1092 {
1093     X509 **certs;
1094     size_t n_certs;
1095     struct stat s;
1096
1097     if (!strcmp(file_name, "none")) {
1098         verify_peer_cert = false;
1099         VLOG_WARN("Peer certificate validation disabled "
1100                   "(this is a security risk)");
1101     } else if (bootstrap && stat(file_name, &s) && errno == ENOENT) {
1102         bootstrap_ca_cert = true;
1103     } else if (!read_cert_file(file_name, &certs, &n_certs)) {
1104         size_t i;
1105
1106         /* Set up list of CAs that the server will accept from the client. */
1107         for (i = 0; i < n_certs; i++) {
1108             /* SSL_CTX_add_client_CA makes a copy of the relevant data. */
1109             if (SSL_CTX_add_client_CA(ctx, certs[i]) != 1) {
1110                 VLOG_ERR("failed to add client certificate %d from %s: %s",
1111                          i, file_name,
1112                          ERR_error_string(ERR_get_error(), NULL));
1113             } else {
1114                 log_ca_cert(file_name, certs[i]);
1115             }
1116             X509_free(certs[i]);
1117         }
1118         free(certs);
1119
1120         /* Set up CAs for OpenSSL to trust in verifying the peer's
1121          * certificate. */
1122         if (SSL_CTX_load_verify_locations(ctx, file_name, NULL) != 1) {
1123             VLOG_ERR("SSL_CTX_load_verify_locations: %s",
1124                      ERR_error_string(ERR_get_error(), NULL));
1125             return;
1126         }
1127
1128         bootstrap_ca_cert = false;
1129     }
1130     ca_cert.read = true;
1131 }
1132
1133 /* Sets 'file_name' as the name of the file from which to read the CA
1134  * certificate used to verify the peer within SSL connections.  If 'bootstrap'
1135  * is false, the file must exist.  If 'bootstrap' is false, then the file is
1136  * read if it is exists; if it does not, then it will be created from the CA
1137  * certificate received from the peer on the first SSL connection. */
1138 void
1139 stream_ssl_set_ca_cert_file(const char *file_name, bool bootstrap)
1140 {
1141     if (!update_ssl_config(&ca_cert, file_name)) {
1142         return;
1143     }
1144
1145     stream_ssl_set_ca_cert_file__(file_name, bootstrap);
1146 }
1147
1148