2 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc.
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:
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
18 #include "stream-ssl.h"
24 #include <sys/types.h>
25 #include <sys/socket.h>
26 #include <netinet/tcp.h>
27 #include <openssl/err.h>
28 #include <openssl/rand.h>
29 #include <openssl/ssl.h>
30 #include <openssl/x509v3.h>
36 #include "dynamic-string.h"
39 #include "openflow/openflow.h"
41 #include "poll-loop.h"
43 #include "socket-util.h"
45 #include "stream-provider.h"
51 /* Ref: https://www.openssl.org/support/faq.html#PROG2
52 * Your application must link against the same version of the Win32 C-Runtime
53 * against which your openssl libraries were linked. The default version for
54 * OpenSSL is /MD - "Multithreaded DLL". If we compile Open vSwitch with
55 * something other than /MD, instead of re-compiling OpenSSL
56 * toolkit, openssl/applink.c can be #included. Also, it is important
57 * to add CRYPTO_malloc_init prior first call to OpenSSL.
59 * XXX: The behavior of the following #include when Open vSwitch is
60 * compiled with /MD is not tested. */
61 #include <openssl/applink.c>
62 #define SHUT_RDWR SD_BOTH
65 VLOG_DEFINE_THIS_MODULE(stream_ssl);
83 enum session_type type;
88 unsigned int session_nr;
90 /* rx_want and tx_want record the result of the last call to SSL_read()
91 * and SSL_write(), respectively:
93 * - If the call reported that data needed to be read from the file
94 * descriptor, the corresponding member is set to SSL_READING.
96 * - If the call reported that data needed to be written to the file
97 * descriptor, the corresponding member is set to SSL_WRITING.
99 * - Otherwise, the member is set to SSL_NOTHING, indicating that the
100 * call completed successfully (or with an error) and that there is no
103 * These are needed because there is no way to ask OpenSSL what a data read
104 * or write would require without giving it a buffer to receive into or
105 * data to send, respectively. (Note that the SSL_want() status is
106 * overwritten by each SSL_read() or SSL_write() call, so we can't rely on
109 * A single call to SSL_read() or SSL_write() can perform both reading
110 * and writing and thus invalidate not one of these values but actually
111 * both. Consider this situation, for example:
113 * - SSL_write() blocks on a read, so tx_want gets SSL_READING.
115 * - SSL_read() laters succeeds reading from 'fd' and clears out the
116 * whole receive buffer, so rx_want gets SSL_READING.
118 * - Client calls stream_wait(STREAM_RECV) and stream_wait(STREAM_SEND)
121 * - Now we're stuck blocking until the peer sends us data, even though
122 * SSL_write() could now succeed, which could easily be a deadlock
125 * On the other hand, we can't reset both tx_want and rx_want on every call
126 * to SSL_read() or SSL_write(), because that would produce livelock,
127 * e.g. in this situation:
129 * - SSL_write() blocks, so tx_want gets SSL_READING or SSL_WRITING.
131 * - SSL_read() blocks, so rx_want gets SSL_READING or SSL_WRITING,
132 * but tx_want gets reset to SSL_NOTHING.
134 * - Client calls stream_wait(STREAM_RECV) and stream_wait(STREAM_SEND)
137 * - Client wakes up immediately since SSL_NOTHING in tx_want indicates
138 * that no blocking is necessary.
140 * The solution we adopt here is to set tx_want to SSL_NOTHING after
141 * calling SSL_read() only if the SSL state of the connection changed,
142 * which indicates that an SSL-level renegotiation made some progress, and
143 * similarly for rx_want and SSL_write(). This prevents both the
144 * deadlock and livelock situations above.
146 int rx_want, tx_want;
148 /* A few bytes of header data in case SSL negotiation fails. */
153 /* SSL context created by ssl_init(). */
156 struct ssl_config_file {
157 bool read; /* Whether the file was successfully read. */
158 char *file_name; /* Configured file name, if any. */
159 struct timespec mtime; /* File mtime as of last time we read it. */
162 /* SSL configuration files. */
163 static struct ssl_config_file private_key;
164 static struct ssl_config_file certificate;
165 static struct ssl_config_file ca_cert;
167 /* Ordinarily, the SSL client and server verify each other's certificates using
168 * a CA certificate. Setting this to false disables this behavior. (This is a
170 static bool verify_peer_cert = true;
172 /* Ordinarily, we require a CA certificate for the peer to be locally
173 * available. We can, however, bootstrap the CA certificate from the peer at
174 * the beginning of our first connection then use that certificate on all
175 * subsequent connections, saving it to a file for use in future runs also. In
176 * this case, 'bootstrap_ca_cert' is true. */
177 static bool bootstrap_ca_cert;
179 /* Session number. Used in debug logging messages to uniquely identify a
181 static unsigned int next_session_nr;
183 /* Who knows what can trigger various SSL errors, so let's throttle them down
185 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 25);
187 static int ssl_init(void);
188 static int do_ssl_init(void);
189 static bool ssl_wants_io(int ssl_error);
190 static void ssl_close(struct stream *);
191 static void ssl_clear_txbuf(struct ssl_stream *);
192 static void interpret_queued_ssl_error(const char *function);
193 static int interpret_ssl_error(const char *function, int ret, int error,
195 static DH *tmp_dh_callback(SSL *ssl, int is_export OVS_UNUSED, int keylength);
196 static void log_ca_cert(const char *file_name, X509 *cert);
197 static void stream_ssl_set_ca_cert_file__(const char *file_name,
198 bool bootstrap, bool force);
199 static void ssl_protocol_cb(int write_p, int version, int content_type,
200 const void *, size_t, SSL *, void *sslv_);
201 static bool update_ssl_config(struct ssl_config_file *, const char *file_name);
202 static int sock_errno(void);
203 static void clear_handle(int fd, HANDLE wevent);
206 want_to_poll_events(int want)
224 new_ssl_stream(const char *name, int fd, enum session_type type,
225 enum ssl_state state, struct stream **streamp)
227 struct sockaddr_storage local;
228 socklen_t local_len = sizeof local;
229 struct ssl_stream *sslv;
234 /* Check for all the needful configuration. */
236 if (!private_key.read) {
237 VLOG_ERR("Private key must be configured to use SSL");
238 retval = ENOPROTOOPT;
240 if (!certificate.read) {
241 VLOG_ERR("Certificate must be configured to use SSL");
242 retval = ENOPROTOOPT;
244 if (!ca_cert.read && verify_peer_cert && !bootstrap_ca_cert) {
245 VLOG_ERR("CA certificate must be configured to use SSL");
246 retval = ENOPROTOOPT;
248 if (!retval && !SSL_CTX_check_private_key(ctx)) {
249 VLOG_ERR("Private key does not match certificate public key: %s",
250 ERR_error_string(ERR_get_error(), NULL));
251 retval = ENOPROTOOPT;
257 /* Get the local IP and port information */
258 retval = getsockname(fd, (struct sockaddr *) &local, &local_len);
260 memset(&local, 0, sizeof local);
264 retval = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof on);
266 retval = sock_errno();
267 VLOG_ERR("%s: setsockopt(TCP_NODELAY): %s", name,
268 sock_strerror(retval));
272 /* Create and configure OpenSSL stream. */
275 VLOG_ERR("SSL_new: %s", ERR_error_string(ERR_get_error(), NULL));
276 retval = ENOPROTOOPT;
279 if (SSL_set_fd(ssl, fd) == 0) {
280 VLOG_ERR("SSL_set_fd: %s", ERR_error_string(ERR_get_error(), NULL));
281 retval = ENOPROTOOPT;
284 if (!verify_peer_cert || (bootstrap_ca_cert && type == CLIENT)) {
285 SSL_set_verify(ssl, SSL_VERIFY_NONE, NULL);
288 /* Create and return the ssl_stream. */
289 sslv = xmalloc(sizeof *sslv);
290 stream_init(&sslv->stream, &ssl_stream_class, EAGAIN, name);
295 sslv->wevent = CreateEvent(NULL, FALSE, FALSE, NULL);
299 sslv->rx_want = sslv->tx_want = SSL_NOTHING;
300 sslv->session_nr = next_session_nr++;
303 if (VLOG_IS_DBG_ENABLED()) {
304 SSL_set_msg_callback(ssl, ssl_protocol_cb);
305 SSL_set_msg_callback_arg(ssl, sslv);
308 *streamp = &sslv->stream;
319 static struct ssl_stream *
320 ssl_stream_cast(struct stream *stream)
322 stream_assert_class(stream, &ssl_stream_class);
323 return CONTAINER_OF(stream, struct ssl_stream, stream);
327 ssl_open(const char *name, char *suffix, struct stream **streamp, uint8_t dscp)
336 error = inet_open_active(SOCK_STREAM, suffix, OFP_OLD_PORT, NULL, &fd,
339 int state = error ? STATE_TCP_CONNECTING : STATE_SSL_CONNECTING;
340 return new_ssl_stream(name, fd, CLIENT, state, streamp);
342 VLOG_ERR("%s: connect: %s", name, ovs_strerror(error));
348 do_ca_cert_bootstrap(struct stream *stream)
350 struct ssl_stream *sslv = ssl_stream_cast(stream);
351 STACK_OF(X509) *chain;
357 chain = SSL_get_peer_cert_chain(sslv->ssl);
358 if (!chain || !sk_X509_num(chain)) {
359 VLOG_ERR("could not bootstrap CA cert: no certificate presented by "
363 cert = sk_X509_value(chain, sk_X509_num(chain) - 1);
365 /* Check that 'cert' is self-signed. Otherwise it is not a CA
366 * certificate and we should not attempt to use it as one. */
367 error = X509_check_issued(cert, cert);
369 VLOG_ERR("could not bootstrap CA cert: obtained certificate is "
370 "not self-signed (%s)",
371 X509_verify_cert_error_string(error));
372 if (sk_X509_num(chain) < 2) {
373 VLOG_ERR("only one certificate was received, so probably the peer "
374 "is not configured to send its CA certificate");
379 fd = open(ca_cert.file_name, O_CREAT | O_EXCL | O_WRONLY, 0444);
381 if (errno == EEXIST) {
382 VLOG_INFO_RL(&rl, "reading CA cert %s created by another process",
384 stream_ssl_set_ca_cert_file__(ca_cert.file_name, true, true);
387 VLOG_ERR("could not bootstrap CA cert: creating %s failed: %s",
388 ca_cert.file_name, ovs_strerror(errno));
393 file = fdopen(fd, "w");
396 VLOG_ERR("could not bootstrap CA cert: fdopen failed: %s",
397 ovs_strerror(error));
398 unlink(ca_cert.file_name);
402 if (!PEM_write_X509(file, cert)) {
403 VLOG_ERR("could not bootstrap CA cert: PEM_write_X509 to %s failed: "
404 "%s", ca_cert.file_name,
405 ERR_error_string(ERR_get_error(), NULL));
407 unlink(ca_cert.file_name);
413 VLOG_ERR("could not bootstrap CA cert: writing %s failed: %s",
414 ca_cert.file_name, ovs_strerror(error));
415 unlink(ca_cert.file_name);
419 VLOG_INFO("successfully bootstrapped CA cert to %s", ca_cert.file_name);
420 log_ca_cert(ca_cert.file_name, cert);
421 bootstrap_ca_cert = false;
424 /* SSL_CTX_add_client_CA makes a copy of cert's relevant data. */
425 SSL_CTX_add_client_CA(ctx, cert);
427 /* SSL_CTX_use_certificate() takes ownership of the certificate passed in.
428 * 'cert' is owned by sslv->ssl, so we need to duplicate it. */
429 cert = X509_dup(cert);
433 SSL_CTX_set_cert_store(ctx, X509_STORE_new());
434 if (SSL_CTX_load_verify_locations(ctx, ca_cert.file_name, NULL) != 1) {
435 VLOG_ERR("SSL_CTX_load_verify_locations: %s",
436 ERR_error_string(ERR_get_error(), NULL));
439 VLOG_INFO("killing successful connection to retry using CA cert");
444 ssl_connect(struct stream *stream)
446 struct ssl_stream *sslv = ssl_stream_cast(stream);
449 switch (sslv->state) {
450 case STATE_TCP_CONNECTING:
451 retval = check_connection_completion(sslv->fd);
455 sslv->state = STATE_SSL_CONNECTING;
458 case STATE_SSL_CONNECTING:
459 /* Capture the first few bytes of received data so that we can guess
460 * what kind of funny data we've been sent if SSL negotiation fails. */
461 if (sslv->n_head <= 0) {
462 sslv->n_head = recv(sslv->fd, sslv->head, sizeof sslv->head,
466 retval = (sslv->type == CLIENT
467 ? SSL_connect(sslv->ssl) : SSL_accept(sslv->ssl));
469 int error = SSL_get_error(sslv->ssl, retval);
470 if (retval < 0 && ssl_wants_io(error)) {
475 interpret_ssl_error((sslv->type == CLIENT ? "SSL_connect"
476 : "SSL_accept"), retval, error, &unused);
477 shutdown(sslv->fd, SHUT_RDWR);
478 stream_report_content(sslv->head, sslv->n_head, STREAM_SSL,
479 THIS_MODULE, stream_get_name(stream));
482 } else if (bootstrap_ca_cert) {
483 return do_ca_cert_bootstrap(stream);
484 } else if (verify_peer_cert
485 && ((SSL_get_verify_mode(sslv->ssl)
486 & (SSL_VERIFY_NONE | SSL_VERIFY_PEER))
487 != SSL_VERIFY_PEER)) {
488 /* Two or more SSL connections completed at the same time while we
489 * were in bootstrap mode. Only one of these can finish the
490 * bootstrap successfully. The other one(s) must be rejected
491 * because they were not verified against the bootstrapped CA
492 * certificate. (Alternatively we could verify them against the CA
493 * certificate, but that's more trouble than it's worth. These
494 * connections will succeed the next time they retry, assuming that
495 * they have a certificate against the correct CA.) */
496 VLOG_INFO("rejecting SSL connection during bootstrap race window");
507 ssl_close(struct stream *stream)
509 struct ssl_stream *sslv = ssl_stream_cast(stream);
510 ssl_clear_txbuf(sslv);
512 /* Attempt clean shutdown of the SSL connection. This will work most of
513 * the time, as long as the kernel send buffer has some free space and the
514 * SSL connection isn't renegotiating, etc. That has to be good enough,
515 * since we don't have any way to continue the close operation in the
517 SSL_shutdown(sslv->ssl);
519 /* SSL_shutdown() might have signaled an error, in which case we need to
520 * flush it out of the OpenSSL error queue or the next OpenSSL operation
521 * will falsely signal an error. */
525 clear_handle(sslv->fd, sslv->wevent);
526 closesocket(sslv->fd);
531 interpret_queued_ssl_error(const char *function)
533 int queued_error = ERR_get_error();
534 if (queued_error != 0) {
535 VLOG_WARN_RL(&rl, "%s: %s",
536 function, ERR_error_string(queued_error, NULL));
538 VLOG_ERR_RL(&rl, "%s: SSL_ERROR_SSL without queued error", function);
543 interpret_ssl_error(const char *function, int ret, int error,
550 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_NONE", function);
553 case SSL_ERROR_ZERO_RETURN:
554 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_ZERO_RETURN", function);
557 case SSL_ERROR_WANT_READ:
561 case SSL_ERROR_WANT_WRITE:
565 case SSL_ERROR_WANT_CONNECT:
566 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_CONNECT", function);
569 case SSL_ERROR_WANT_ACCEPT:
570 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_ACCEPT", function);
573 case SSL_ERROR_WANT_X509_LOOKUP:
574 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_X509_LOOKUP",
578 case SSL_ERROR_SYSCALL: {
579 int queued_error = ERR_get_error();
580 if (queued_error == 0) {
583 VLOG_WARN_RL(&rl, "%s: system error (%s)",
584 function, ovs_strerror(status));
587 VLOG_WARN_RL(&rl, "%s: unexpected SSL connection close",
592 VLOG_WARN_RL(&rl, "%s: %s",
593 function, ERR_error_string(queued_error, NULL));
599 interpret_queued_ssl_error(function);
603 VLOG_ERR_RL(&rl, "%s: bad SSL error code %d", function, error);
610 ssl_recv(struct stream *stream, void *buffer, size_t n)
612 struct ssl_stream *sslv = ssl_stream_cast(stream);
616 /* Behavior of zero-byte SSL_read is poorly defined. */
619 old_state = SSL_get_state(sslv->ssl);
620 ret = SSL_read(sslv->ssl, buffer, n);
621 if (old_state != SSL_get_state(sslv->ssl)) {
622 sslv->tx_want = SSL_NOTHING;
624 sslv->rx_want = SSL_NOTHING;
629 int error = SSL_get_error(sslv->ssl, ret);
630 if (error == SSL_ERROR_ZERO_RETURN) {
633 return -interpret_ssl_error("SSL_read", ret, error,
640 ssl_clear_txbuf(struct ssl_stream *sslv)
642 ofpbuf_delete(sslv->txbuf);
647 ssl_do_tx(struct stream *stream)
649 struct ssl_stream *sslv = ssl_stream_cast(stream);
652 int old_state = SSL_get_state(sslv->ssl);
653 int ret = SSL_write(sslv->ssl,
654 ofpbuf_data(sslv->txbuf), ofpbuf_size(sslv->txbuf));
655 if (old_state != SSL_get_state(sslv->ssl)) {
656 sslv->rx_want = SSL_NOTHING;
658 sslv->tx_want = SSL_NOTHING;
660 ofpbuf_pull(sslv->txbuf, ret);
661 if (ofpbuf_size(sslv->txbuf) == 0) {
665 int ssl_error = SSL_get_error(sslv->ssl, ret);
666 if (ssl_error == SSL_ERROR_ZERO_RETURN) {
667 VLOG_WARN_RL(&rl, "SSL_write: connection closed");
670 return interpret_ssl_error("SSL_write", ret, ssl_error,
678 ssl_send(struct stream *stream, const void *buffer, size_t n)
680 struct ssl_stream *sslv = ssl_stream_cast(stream);
687 sslv->txbuf = ofpbuf_clone_data(buffer, n);
688 error = ssl_do_tx(stream);
691 ssl_clear_txbuf(sslv);
703 ssl_run(struct stream *stream)
705 struct ssl_stream *sslv = ssl_stream_cast(stream);
707 if (sslv->txbuf && ssl_do_tx(stream) != EAGAIN) {
708 ssl_clear_txbuf(sslv);
713 ssl_run_wait(struct stream *stream)
715 struct ssl_stream *sslv = ssl_stream_cast(stream);
717 if (sslv->tx_want != SSL_NOTHING) {
718 poll_fd_wait_event(sslv->fd, sslv->wevent,
719 want_to_poll_events(sslv->tx_want));
724 ssl_wait(struct stream *stream, enum stream_wait_type wait)
726 struct ssl_stream *sslv = ssl_stream_cast(stream);
730 if (stream_connect(stream) != EAGAIN) {
731 poll_immediate_wake();
733 switch (sslv->state) {
734 case STATE_TCP_CONNECTING:
735 poll_fd_wait_event(sslv->fd, sslv->wevent, POLLOUT);
738 case STATE_SSL_CONNECTING:
739 /* ssl_connect() called SSL_accept() or SSL_connect(), which
740 * set up the status that we test here. */
741 poll_fd_wait_event(sslv->fd, sslv->wevent,
742 want_to_poll_events(SSL_want(sslv->ssl)));
752 if (sslv->rx_want != SSL_NOTHING) {
753 poll_fd_wait_event(sslv->fd, sslv->wevent,
754 want_to_poll_events(sslv->rx_want));
756 poll_immediate_wake();
762 /* We have room in our tx queue. */
763 poll_immediate_wake();
765 /* stream_run_wait() will do the right thing; don't bother with
775 const struct stream_class ssl_stream_class = {
777 true, /* needs_probes */
779 ssl_close, /* close */
780 ssl_connect, /* connect */
784 ssl_run_wait, /* run_wait */
792 struct pstream pstream;
797 const struct pstream_class pssl_pstream_class;
799 static struct pssl_pstream *
800 pssl_pstream_cast(struct pstream *pstream)
802 pstream_assert_class(pstream, &pssl_pstream_class);
803 return CONTAINER_OF(pstream, struct pssl_pstream, pstream);
807 pssl_open(const char *name OVS_UNUSED, char *suffix, struct pstream **pstreamp,
810 char bound_name[SS_NTOP_BUFSIZE + 16];
811 char addrbuf[SS_NTOP_BUFSIZE];
812 struct sockaddr_storage ss;
813 struct pssl_pstream *pssl;
823 fd = inet_open_passive(SOCK_STREAM, suffix, OFP_OLD_PORT, &ss, dscp);
828 port = ss_get_port(&ss);
829 snprintf(bound_name, sizeof bound_name, "ptcp:%"PRIu16":%s",
830 port, ss_format_address(&ss, addrbuf, sizeof addrbuf));
832 pssl = xmalloc(sizeof *pssl);
833 pstream_init(&pssl->pstream, &pssl_pstream_class, bound_name);
834 pstream_set_bound_port(&pssl->pstream, htons(port));
837 pssl->wevent = CreateEvent(NULL, FALSE, FALSE, NULL);
839 *pstreamp = &pssl->pstream;
844 pssl_close(struct pstream *pstream)
846 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
847 clear_handle(pssl->fd, pssl->wevent);
848 closesocket(pssl->fd);
853 pssl_accept(struct pstream *pstream, struct stream **new_streamp)
855 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
856 char name[SS_NTOP_BUFSIZE + 16];
857 char addrbuf[SS_NTOP_BUFSIZE];
858 struct sockaddr_storage ss;
859 socklen_t ss_len = sizeof ss;
863 new_fd = accept(pssl->fd, (struct sockaddr *) &ss, &ss_len);
865 error = sock_errno();
867 if (error == WSAEWOULDBLOCK) {
871 if (error != EAGAIN) {
872 VLOG_DBG_RL(&rl, "accept: %s", sock_strerror(error));
877 error = set_nonblocking(new_fd);
883 snprintf(name, sizeof name, "tcp:%s:%"PRIu16,
884 ss_format_address(&ss, addrbuf, sizeof addrbuf),
886 return new_ssl_stream(name, new_fd, SERVER, STATE_SSL_CONNECTING,
891 pssl_wait(struct pstream *pstream)
893 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
894 poll_fd_wait_event(pssl->fd, pssl->wevent, POLLIN);
898 pssl_set_dscp(struct pstream *pstream, uint8_t dscp)
900 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
901 return set_dscp(pssl->fd, dscp);
904 const struct pstream_class pssl_pstream_class = {
915 * Returns true if OpenSSL error is WANT_READ or WANT_WRITE, indicating that
916 * OpenSSL is requesting that we call it back when the socket is ready for read
917 * or writing, respectively.
920 ssl_wants_io(int ssl_error)
922 return (ssl_error == SSL_ERROR_WANT_WRITE
923 || ssl_error == SSL_ERROR_WANT_READ);
929 static int init_status = -1;
930 if (init_status < 0) {
931 init_status = do_ssl_init();
932 ovs_assert(init_status >= 0);
943 /* The following call is needed if we "#include <openssl/applink.c>". */
944 CRYPTO_malloc_init();
947 SSL_load_error_strings();
949 if (!RAND_status()) {
950 /* We occasionally see OpenSSL fail to seed its random number generator
951 * in heavily loaded hypervisors. I suspect the following scenario:
953 * 1. OpenSSL calls read() to get 32 bytes from /dev/urandom.
954 * 2. The kernel generates 10 bytes of randomness and copies it out.
955 * 3. A signal arrives (perhaps SIGALRM).
956 * 4. The kernel interrupts the system call to service the signal.
957 * 5. Userspace gets 10 bytes of entropy.
958 * 6. OpenSSL doesn't read again to get the final 22 bytes. Therefore
959 * OpenSSL doesn't have enough entropy to consider itself
962 * The only part I'm not entirely sure about is #6, because the OpenSSL
963 * code is so hard to read. */
967 VLOG_WARN("OpenSSL random seeding failed, reseeding ourselves");
969 retval = get_entropy(seed, sizeof seed);
971 VLOG_ERR("failed to obtain entropy (%s)",
972 ovs_retval_to_string(retval));
973 return retval > 0 ? retval : ENOPROTOOPT;
976 RAND_seed(seed, sizeof seed);
979 /* New OpenSSL changed TLSv1_method() to return a "const" pointer, so the
980 * cast is needed to avoid a warning with those newer versions. */
981 method = CONST_CAST(SSL_METHOD *, TLSv1_method());
982 if (method == NULL) {
983 VLOG_ERR("TLSv1_method: %s", ERR_error_string(ERR_get_error(), NULL));
987 ctx = SSL_CTX_new(method);
989 VLOG_ERR("SSL_CTX_new: %s", ERR_error_string(ERR_get_error(), NULL));
992 SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
993 SSL_CTX_set_tmp_dh_callback(ctx, tmp_dh_callback);
994 SSL_CTX_set_mode(ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
995 SSL_CTX_set_mode(ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
996 SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1003 tmp_dh_callback(SSL *ssl OVS_UNUSED, int is_export OVS_UNUSED, int keylength)
1008 DH *(*constructor)(void);
1011 static struct dh dh_table[] = {
1012 {1024, NULL, get_dh1024},
1013 {2048, NULL, get_dh2048},
1014 {4096, NULL, get_dh4096},
1019 for (dh = dh_table; dh < &dh_table[ARRAY_SIZE(dh_table)]; dh++) {
1020 if (dh->keylength == keylength) {
1022 dh->dh = dh->constructor();
1030 VLOG_ERR_RL(&rl, "no Diffie-Hellman parameters for key length %d",
1035 /* Returns true if SSL is at least partially configured. */
1037 stream_ssl_is_configured(void)
1039 return private_key.file_name || certificate.file_name || ca_cert.file_name;
1043 update_ssl_config(struct ssl_config_file *config, const char *file_name)
1045 struct timespec mtime;
1048 if (ssl_init() || !file_name) {
1052 /* If the file name hasn't changed and neither has the file contents, stop
1054 error = get_mtime(file_name, &mtime);
1055 if (error && error != ENOENT) {
1056 VLOG_ERR_RL(&rl, "%s: stat failed (%s)",
1057 file_name, ovs_strerror(error));
1059 if (config->file_name
1060 && !strcmp(config->file_name, file_name)
1061 && mtime.tv_sec == config->mtime.tv_sec
1062 && mtime.tv_nsec == config->mtime.tv_nsec) {
1066 /* Update 'config'. */
1067 config->mtime = mtime;
1068 if (file_name != config->file_name) {
1069 free(config->file_name);
1070 config->file_name = xstrdup(file_name);
1076 stream_ssl_set_private_key_file__(const char *file_name)
1078 if (SSL_CTX_use_PrivateKey_file(ctx, file_name, SSL_FILETYPE_PEM) == 1) {
1079 private_key.read = true;
1081 VLOG_ERR("SSL_use_PrivateKey_file: %s",
1082 ERR_error_string(ERR_get_error(), NULL));
1087 stream_ssl_set_private_key_file(const char *file_name)
1089 if (update_ssl_config(&private_key, file_name)) {
1090 stream_ssl_set_private_key_file__(file_name);
1095 stream_ssl_set_certificate_file__(const char *file_name)
1097 if (SSL_CTX_use_certificate_chain_file(ctx, file_name) == 1) {
1098 certificate.read = true;
1100 VLOG_ERR("SSL_use_certificate_file: %s",
1101 ERR_error_string(ERR_get_error(), NULL));
1106 stream_ssl_set_certificate_file(const char *file_name)
1108 if (update_ssl_config(&certificate, file_name)) {
1109 stream_ssl_set_certificate_file__(file_name);
1113 /* Sets the private key and certificate files in one operation. Use this
1114 * interface, instead of calling stream_ssl_set_private_key_file() and
1115 * stream_ssl_set_certificate_file() individually, in the main loop of a
1116 * long-running program whose key and certificate might change at runtime.
1118 * This is important because of OpenSSL's behavior. If an OpenSSL context
1119 * already has a certificate, and stream_ssl_set_private_key_file() is called
1120 * to install a new private key, OpenSSL will report an error because the new
1121 * private key does not match the old certificate. The other order, of setting
1122 * a new certificate, then setting a new private key, does work.
1124 * If this were the only problem, calling stream_ssl_set_certificate_file()
1125 * before stream_ssl_set_private_key_file() would fix it. But, if the private
1126 * key is changed before the certificate (e.g. someone "scp"s or "mv"s the new
1127 * private key in place before the certificate), then OpenSSL would reject that
1128 * change, and then the change of certificate would succeed, but there would be
1129 * no associated private key (because it had only changed once and therefore
1130 * there was no point in re-reading it).
1132 * This function avoids both problems by, whenever either the certificate or
1133 * the private key file changes, re-reading both of them, in the correct order.
1136 stream_ssl_set_key_and_cert(const char *private_key_file,
1137 const char *certificate_file)
1139 if (update_ssl_config(&private_key, private_key_file)
1140 || update_ssl_config(&certificate, certificate_file)) {
1141 stream_ssl_set_certificate_file__(certificate_file);
1142 stream_ssl_set_private_key_file__(private_key_file);
1146 /* Reads the X509 certificate or certificates in file 'file_name'. On success,
1147 * stores the address of the first element in an array of pointers to
1148 * certificates in '*certs' and the number of certificates in the array in
1149 * '*n_certs', and returns 0. On failure, stores a null pointer in '*certs', 0
1150 * in '*n_certs', and returns a positive errno value.
1152 * The caller is responsible for freeing '*certs'. */
1154 read_cert_file(const char *file_name, X509 ***certs, size_t *n_certs)
1157 size_t allocated_certs = 0;
1162 file = fopen(file_name, "r");
1164 VLOG_ERR("failed to open %s for reading: %s",
1165 file_name, ovs_strerror(errno));
1173 /* Read certificate from file. */
1174 certificate = PEM_read_X509(file, NULL, NULL, NULL);
1178 VLOG_ERR("PEM_read_X509 failed reading %s: %s",
1179 file_name, ERR_error_string(ERR_get_error(), NULL));
1180 for (i = 0; i < *n_certs; i++) {
1181 X509_free((*certs)[i]);
1189 /* Add certificate to array. */
1190 if (*n_certs >= allocated_certs) {
1191 *certs = x2nrealloc(*certs, &allocated_certs, sizeof **certs);
1193 (*certs)[(*n_certs)++] = certificate;
1195 /* Are there additional certificates in the file? */
1198 } while (isspace(c));
1209 /* Sets 'file_name' as the name of a file containing one or more X509
1210 * certificates to send to the peer. Typical use in OpenFlow is to send the CA
1211 * certificate to the peer, which enables a switch to pick up the controller's
1212 * CA certificate on its first connection. */
1214 stream_ssl_set_peer_ca_cert_file(const char *file_name)
1224 if (!read_cert_file(file_name, &certs, &n_certs)) {
1225 for (i = 0; i < n_certs; i++) {
1226 if (SSL_CTX_add_extra_chain_cert(ctx, certs[i]) != 1) {
1227 VLOG_ERR("SSL_CTX_add_extra_chain_cert: %s",
1228 ERR_error_string(ERR_get_error(), NULL));
1235 /* Logs fingerprint of CA certificate 'cert' obtained from 'file_name'. */
1237 log_ca_cert(const char *file_name, X509 *cert)
1239 unsigned char digest[EVP_MAX_MD_SIZE];
1240 unsigned int n_bytes;
1245 if (!X509_digest(cert, EVP_sha1(), digest, &n_bytes)) {
1246 ds_put_cstr(&fp, "<out of memory>");
1249 for (i = 0; i < n_bytes; i++) {
1251 ds_put_char(&fp, ':');
1253 ds_put_format(&fp, "%02x", digest[i]);
1256 subject = X509_NAME_oneline(X509_get_subject_name(cert), NULL, 0);
1257 VLOG_INFO("Trusting CA cert from %s (%s) (fingerprint %s)", file_name,
1258 subject ? subject : "<out of memory>", ds_cstr(&fp));
1259 OPENSSL_free(subject);
1264 stream_ssl_set_ca_cert_file__(const char *file_name,
1265 bool bootstrap, bool force)
1271 if (!update_ssl_config(&ca_cert, file_name) && !force) {
1275 if (!strcmp(file_name, "none")) {
1276 verify_peer_cert = false;
1277 VLOG_WARN("Peer certificate validation disabled "
1278 "(this is a security risk)");
1279 } else if (bootstrap && stat(file_name, &s) && errno == ENOENT) {
1280 bootstrap_ca_cert = true;
1281 } else if (!read_cert_file(file_name, &certs, &n_certs)) {
1284 /* Set up list of CAs that the server will accept from the client. */
1285 for (i = 0; i < n_certs; i++) {
1286 /* SSL_CTX_add_client_CA makes a copy of the relevant data. */
1287 if (SSL_CTX_add_client_CA(ctx, certs[i]) != 1) {
1288 VLOG_ERR("failed to add client certificate %"PRIuSIZE" from %s: %s",
1290 ERR_error_string(ERR_get_error(), NULL));
1292 log_ca_cert(file_name, certs[i]);
1294 X509_free(certs[i]);
1298 /* Set up CAs for OpenSSL to trust in verifying the peer's
1300 SSL_CTX_set_cert_store(ctx, X509_STORE_new());
1301 if (SSL_CTX_load_verify_locations(ctx, file_name, NULL) != 1) {
1302 VLOG_ERR("SSL_CTX_load_verify_locations: %s",
1303 ERR_error_string(ERR_get_error(), NULL));
1307 bootstrap_ca_cert = false;
1309 ca_cert.read = true;
1312 /* Sets 'file_name' as the name of the file from which to read the CA
1313 * certificate used to verify the peer within SSL connections. If 'bootstrap'
1314 * is false, the file must exist. If 'bootstrap' is false, then the file is
1315 * read if it is exists; if it does not, then it will be created from the CA
1316 * certificate received from the peer on the first SSL connection. */
1318 stream_ssl_set_ca_cert_file(const char *file_name, bool bootstrap)
1320 stream_ssl_set_ca_cert_file__(file_name, bootstrap, false);
1323 /* SSL protocol logging. */
1326 ssl_alert_level_to_string(uint8_t type)
1329 case 1: return "warning";
1330 case 2: return "fatal";
1331 default: return "<unknown>";
1336 ssl_alert_description_to_string(uint8_t type)
1339 case 0: return "close_notify";
1340 case 10: return "unexpected_message";
1341 case 20: return "bad_record_mac";
1342 case 21: return "decryption_failed";
1343 case 22: return "record_overflow";
1344 case 30: return "decompression_failure";
1345 case 40: return "handshake_failure";
1346 case 42: return "bad_certificate";
1347 case 43: return "unsupported_certificate";
1348 case 44: return "certificate_revoked";
1349 case 45: return "certificate_expired";
1350 case 46: return "certificate_unknown";
1351 case 47: return "illegal_parameter";
1352 case 48: return "unknown_ca";
1353 case 49: return "access_denied";
1354 case 50: return "decode_error";
1355 case 51: return "decrypt_error";
1356 case 60: return "export_restriction";
1357 case 70: return "protocol_version";
1358 case 71: return "insufficient_security";
1359 case 80: return "internal_error";
1360 case 90: return "user_canceled";
1361 case 100: return "no_renegotiation";
1362 default: return "<unknown>";
1367 ssl_handshake_type_to_string(uint8_t type)
1370 case 0: return "hello_request";
1371 case 1: return "client_hello";
1372 case 2: return "server_hello";
1373 case 11: return "certificate";
1374 case 12: return "server_key_exchange";
1375 case 13: return "certificate_request";
1376 case 14: return "server_hello_done";
1377 case 15: return "certificate_verify";
1378 case 16: return "client_key_exchange";
1379 case 20: return "finished";
1380 default: return "<unknown>";
1385 ssl_protocol_cb(int write_p, int version OVS_UNUSED, int content_type,
1386 const void *buf_, size_t len, SSL *ssl OVS_UNUSED, void *sslv_)
1388 const struct ssl_stream *sslv = sslv_;
1389 const uint8_t *buf = buf_;
1392 if (!VLOG_IS_DBG_ENABLED()) {
1397 if (content_type == 20) {
1398 ds_put_cstr(&details, "change_cipher_spec");
1399 } else if (content_type == 21) {
1400 ds_put_format(&details, "alert: %s, %s",
1401 ssl_alert_level_to_string(buf[0]),
1402 ssl_alert_description_to_string(buf[1]));
1403 } else if (content_type == 22) {
1404 ds_put_format(&details, "handshake: %s",
1405 ssl_handshake_type_to_string(buf[0]));
1407 ds_put_format(&details, "type %d", content_type);
1410 VLOG_DBG("%s%u%s%s %s (%"PRIuSIZE" bytes)",
1411 sslv->type == CLIENT ? "client" : "server",
1412 sslv->session_nr, write_p ? "-->" : "<--",
1413 stream_get_name(&sslv->stream), ds_cstr(&details), len);
1415 ds_destroy(&details);
1419 clear_handle(int fd OVS_UNUSED, HANDLE wevent OVS_UNUSED)
1423 WSAEventSelect(fd, NULL, 0);
1426 CloseHandle(wevent);