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);
301 sslv->rx_want = sslv->tx_want = SSL_NOTHING;
302 sslv->session_nr = next_session_nr++;
305 if (VLOG_IS_DBG_ENABLED()) {
306 SSL_set_msg_callback(ssl, ssl_protocol_cb);
307 SSL_set_msg_callback_arg(ssl, sslv);
310 *streamp = &sslv->stream;
321 static struct ssl_stream *
322 ssl_stream_cast(struct stream *stream)
324 stream_assert_class(stream, &ssl_stream_class);
325 return CONTAINER_OF(stream, struct ssl_stream, stream);
329 ssl_open(const char *name, char *suffix, struct stream **streamp, uint8_t dscp)
338 error = inet_open_active(SOCK_STREAM, suffix, OFP_OLD_PORT, NULL, &fd,
341 int state = error ? STATE_TCP_CONNECTING : STATE_SSL_CONNECTING;
342 return new_ssl_stream(name, fd, CLIENT, state, streamp);
344 VLOG_ERR("%s: connect: %s", name, ovs_strerror(error));
350 do_ca_cert_bootstrap(struct stream *stream)
352 struct ssl_stream *sslv = ssl_stream_cast(stream);
353 STACK_OF(X509) *chain;
359 chain = SSL_get_peer_cert_chain(sslv->ssl);
360 if (!chain || !sk_X509_num(chain)) {
361 VLOG_ERR("could not bootstrap CA cert: no certificate presented by "
365 cert = sk_X509_value(chain, sk_X509_num(chain) - 1);
367 /* Check that 'cert' is self-signed. Otherwise it is not a CA
368 * certificate and we should not attempt to use it as one. */
369 error = X509_check_issued(cert, cert);
371 VLOG_ERR("could not bootstrap CA cert: obtained certificate is "
372 "not self-signed (%s)",
373 X509_verify_cert_error_string(error));
374 if (sk_X509_num(chain) < 2) {
375 VLOG_ERR("only one certificate was received, so probably the peer "
376 "is not configured to send its CA certificate");
381 fd = open(ca_cert.file_name, O_CREAT | O_EXCL | O_WRONLY, 0444);
383 if (errno == EEXIST) {
384 VLOG_INFO_RL(&rl, "reading CA cert %s created by another process",
386 stream_ssl_set_ca_cert_file__(ca_cert.file_name, true, true);
389 VLOG_ERR("could not bootstrap CA cert: creating %s failed: %s",
390 ca_cert.file_name, ovs_strerror(errno));
395 file = fdopen(fd, "w");
398 VLOG_ERR("could not bootstrap CA cert: fdopen failed: %s",
399 ovs_strerror(error));
400 unlink(ca_cert.file_name);
404 if (!PEM_write_X509(file, cert)) {
405 VLOG_ERR("could not bootstrap CA cert: PEM_write_X509 to %s failed: "
406 "%s", ca_cert.file_name,
407 ERR_error_string(ERR_get_error(), NULL));
409 unlink(ca_cert.file_name);
415 VLOG_ERR("could not bootstrap CA cert: writing %s failed: %s",
416 ca_cert.file_name, ovs_strerror(error));
417 unlink(ca_cert.file_name);
421 VLOG_INFO("successfully bootstrapped CA cert to %s", ca_cert.file_name);
422 log_ca_cert(ca_cert.file_name, cert);
423 bootstrap_ca_cert = false;
426 /* SSL_CTX_add_client_CA makes a copy of cert's relevant data. */
427 SSL_CTX_add_client_CA(ctx, cert);
429 /* SSL_CTX_use_certificate() takes ownership of the certificate passed in.
430 * 'cert' is owned by sslv->ssl, so we need to duplicate it. */
431 cert = X509_dup(cert);
435 SSL_CTX_set_cert_store(ctx, X509_STORE_new());
436 if (SSL_CTX_load_verify_locations(ctx, ca_cert.file_name, NULL) != 1) {
437 VLOG_ERR("SSL_CTX_load_verify_locations: %s",
438 ERR_error_string(ERR_get_error(), NULL));
441 VLOG_INFO("killing successful connection to retry using CA cert");
446 ssl_connect(struct stream *stream)
448 struct ssl_stream *sslv = ssl_stream_cast(stream);
451 switch (sslv->state) {
452 case STATE_TCP_CONNECTING:
453 retval = check_connection_completion(sslv->fd);
457 sslv->state = STATE_SSL_CONNECTING;
460 case STATE_SSL_CONNECTING:
461 /* Capture the first few bytes of received data so that we can guess
462 * what kind of funny data we've been sent if SSL negotiation fails. */
463 if (sslv->n_head <= 0) {
464 sslv->n_head = recv(sslv->fd, sslv->head, sizeof sslv->head,
468 retval = (sslv->type == CLIENT
469 ? SSL_connect(sslv->ssl) : SSL_accept(sslv->ssl));
471 int error = SSL_get_error(sslv->ssl, retval);
472 if (retval < 0 && ssl_wants_io(error)) {
477 interpret_ssl_error((sslv->type == CLIENT ? "SSL_connect"
478 : "SSL_accept"), retval, error, &unused);
479 shutdown(sslv->fd, SHUT_RDWR);
480 stream_report_content(sslv->head, sslv->n_head, STREAM_SSL,
481 THIS_MODULE, stream_get_name(stream));
484 } else if (bootstrap_ca_cert) {
485 return do_ca_cert_bootstrap(stream);
486 } else if (verify_peer_cert
487 && ((SSL_get_verify_mode(sslv->ssl)
488 & (SSL_VERIFY_NONE | SSL_VERIFY_PEER))
489 != SSL_VERIFY_PEER)) {
490 /* Two or more SSL connections completed at the same time while we
491 * were in bootstrap mode. Only one of these can finish the
492 * bootstrap successfully. The other one(s) must be rejected
493 * because they were not verified against the bootstrapped CA
494 * certificate. (Alternatively we could verify them against the CA
495 * certificate, but that's more trouble than it's worth. These
496 * connections will succeed the next time they retry, assuming that
497 * they have a certificate against the correct CA.) */
498 VLOG_INFO("rejecting SSL connection during bootstrap race window");
509 ssl_close(struct stream *stream)
511 struct ssl_stream *sslv = ssl_stream_cast(stream);
512 ssl_clear_txbuf(sslv);
514 /* Attempt clean shutdown of the SSL connection. This will work most of
515 * the time, as long as the kernel send buffer has some free space and the
516 * SSL connection isn't renegotiating, etc. That has to be good enough,
517 * since we don't have any way to continue the close operation in the
519 SSL_shutdown(sslv->ssl);
521 /* SSL_shutdown() might have signaled an error, in which case we need to
522 * flush it out of the OpenSSL error queue or the next OpenSSL operation
523 * will falsely signal an error. */
527 clear_handle(sslv->fd, sslv->wevent);
528 closesocket(sslv->fd);
533 interpret_queued_ssl_error(const char *function)
535 int queued_error = ERR_get_error();
536 if (queued_error != 0) {
537 VLOG_WARN_RL(&rl, "%s: %s",
538 function, ERR_error_string(queued_error, NULL));
540 VLOG_ERR_RL(&rl, "%s: SSL_ERROR_SSL without queued error", function);
545 interpret_ssl_error(const char *function, int ret, int error,
552 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_NONE", function);
555 case SSL_ERROR_ZERO_RETURN:
556 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_ZERO_RETURN", function);
559 case SSL_ERROR_WANT_READ:
563 case SSL_ERROR_WANT_WRITE:
567 case SSL_ERROR_WANT_CONNECT:
568 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_CONNECT", function);
571 case SSL_ERROR_WANT_ACCEPT:
572 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_ACCEPT", function);
575 case SSL_ERROR_WANT_X509_LOOKUP:
576 VLOG_ERR_RL(&rl, "%s: unexpected SSL_ERROR_WANT_X509_LOOKUP",
580 case SSL_ERROR_SYSCALL: {
581 int queued_error = ERR_get_error();
582 if (queued_error == 0) {
585 VLOG_WARN_RL(&rl, "%s: system error (%s)",
586 function, ovs_strerror(status));
589 VLOG_WARN_RL(&rl, "%s: unexpected SSL connection close",
594 VLOG_WARN_RL(&rl, "%s: %s",
595 function, ERR_error_string(queued_error, NULL));
601 interpret_queued_ssl_error(function);
605 VLOG_ERR_RL(&rl, "%s: bad SSL error code %d", function, error);
612 ssl_recv(struct stream *stream, void *buffer, size_t n)
614 struct ssl_stream *sslv = ssl_stream_cast(stream);
618 /* Behavior of zero-byte SSL_read is poorly defined. */
621 old_state = SSL_get_state(sslv->ssl);
622 ret = SSL_read(sslv->ssl, buffer, n);
623 if (old_state != SSL_get_state(sslv->ssl)) {
624 sslv->tx_want = SSL_NOTHING;
626 sslv->rx_want = SSL_NOTHING;
631 int error = SSL_get_error(sslv->ssl, ret);
632 if (error == SSL_ERROR_ZERO_RETURN) {
635 return -interpret_ssl_error("SSL_read", ret, error,
642 ssl_clear_txbuf(struct ssl_stream *sslv)
644 ofpbuf_delete(sslv->txbuf);
649 ssl_do_tx(struct stream *stream)
651 struct ssl_stream *sslv = ssl_stream_cast(stream);
654 int old_state = SSL_get_state(sslv->ssl);
655 int ret = SSL_write(sslv->ssl,
656 ofpbuf_data(sslv->txbuf), ofpbuf_size(sslv->txbuf));
657 if (old_state != SSL_get_state(sslv->ssl)) {
658 sslv->rx_want = SSL_NOTHING;
660 sslv->tx_want = SSL_NOTHING;
662 ofpbuf_pull(sslv->txbuf, ret);
663 if (ofpbuf_size(sslv->txbuf) == 0) {
667 int ssl_error = SSL_get_error(sslv->ssl, ret);
668 if (ssl_error == SSL_ERROR_ZERO_RETURN) {
669 VLOG_WARN_RL(&rl, "SSL_write: connection closed");
672 return interpret_ssl_error("SSL_write", ret, ssl_error,
680 ssl_send(struct stream *stream, const void *buffer, size_t n)
682 struct ssl_stream *sslv = ssl_stream_cast(stream);
689 sslv->txbuf = ofpbuf_clone_data(buffer, n);
690 error = ssl_do_tx(stream);
693 ssl_clear_txbuf(sslv);
705 ssl_run(struct stream *stream)
707 struct ssl_stream *sslv = ssl_stream_cast(stream);
709 if (sslv->txbuf && ssl_do_tx(stream) != EAGAIN) {
710 ssl_clear_txbuf(sslv);
715 ssl_run_wait(struct stream *stream)
717 struct ssl_stream *sslv = ssl_stream_cast(stream);
719 if (sslv->tx_want != SSL_NOTHING) {
720 poll_fd_wait_event(sslv->fd, sslv->wevent,
721 want_to_poll_events(sslv->tx_want));
726 ssl_wait(struct stream *stream, enum stream_wait_type wait)
728 struct ssl_stream *sslv = ssl_stream_cast(stream);
732 if (stream_connect(stream) != EAGAIN) {
733 poll_immediate_wake();
735 switch (sslv->state) {
736 case STATE_TCP_CONNECTING:
737 poll_fd_wait_event(sslv->fd, sslv->wevent, POLLOUT);
740 case STATE_SSL_CONNECTING:
741 /* ssl_connect() called SSL_accept() or SSL_connect(), which
742 * set up the status that we test here. */
743 poll_fd_wait_event(sslv->fd, sslv->wevent,
744 want_to_poll_events(SSL_want(sslv->ssl)));
754 if (sslv->rx_want != SSL_NOTHING) {
755 poll_fd_wait_event(sslv->fd, sslv->wevent,
756 want_to_poll_events(sslv->rx_want));
758 poll_immediate_wake();
764 /* We have room in our tx queue. */
765 poll_immediate_wake();
767 /* stream_run_wait() will do the right thing; don't bother with
777 const struct stream_class ssl_stream_class = {
779 true, /* needs_probes */
781 ssl_close, /* close */
782 ssl_connect, /* connect */
786 ssl_run_wait, /* run_wait */
794 struct pstream pstream;
799 const struct pstream_class pssl_pstream_class;
801 static struct pssl_pstream *
802 pssl_pstream_cast(struct pstream *pstream)
804 pstream_assert_class(pstream, &pssl_pstream_class);
805 return CONTAINER_OF(pstream, struct pssl_pstream, pstream);
809 pssl_open(const char *name OVS_UNUSED, char *suffix, struct pstream **pstreamp,
812 char bound_name[SS_NTOP_BUFSIZE + 16];
813 char addrbuf[SS_NTOP_BUFSIZE];
814 struct sockaddr_storage ss;
815 struct pssl_pstream *pssl;
825 fd = inet_open_passive(SOCK_STREAM, suffix, OFP_OLD_PORT, &ss, dscp);
830 port = ss_get_port(&ss);
831 snprintf(bound_name, sizeof bound_name, "ptcp:%"PRIu16":%s",
832 port, ss_format_address(&ss, addrbuf, sizeof addrbuf));
834 pssl = xmalloc(sizeof *pssl);
835 pstream_init(&pssl->pstream, &pssl_pstream_class, bound_name);
836 pstream_set_bound_port(&pssl->pstream, htons(port));
839 pssl->wevent = CreateEvent(NULL, FALSE, FALSE, NULL);
843 *pstreamp = &pssl->pstream;
848 pssl_close(struct pstream *pstream)
850 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
851 clear_handle(pssl->fd, pssl->wevent);
852 closesocket(pssl->fd);
857 pssl_accept(struct pstream *pstream, struct stream **new_streamp)
859 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
860 char name[SS_NTOP_BUFSIZE + 16];
861 char addrbuf[SS_NTOP_BUFSIZE];
862 struct sockaddr_storage ss;
863 socklen_t ss_len = sizeof ss;
867 new_fd = accept(pssl->fd, (struct sockaddr *) &ss, &ss_len);
869 error = sock_errno();
871 if (error == WSAEWOULDBLOCK) {
875 if (error != EAGAIN) {
876 VLOG_DBG_RL(&rl, "accept: %s", sock_strerror(error));
881 error = set_nonblocking(new_fd);
887 snprintf(name, sizeof name, "tcp:%s:%"PRIu16,
888 ss_format_address(&ss, addrbuf, sizeof addrbuf),
890 return new_ssl_stream(name, new_fd, SERVER, STATE_SSL_CONNECTING,
895 pssl_wait(struct pstream *pstream)
897 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
898 poll_fd_wait_event(pssl->fd, pssl->wevent, POLLIN);
902 pssl_set_dscp(struct pstream *pstream, uint8_t dscp)
904 struct pssl_pstream *pssl = pssl_pstream_cast(pstream);
905 return set_dscp(pssl->fd, dscp);
908 const struct pstream_class pssl_pstream_class = {
919 * Returns true if OpenSSL error is WANT_READ or WANT_WRITE, indicating that
920 * OpenSSL is requesting that we call it back when the socket is ready for read
921 * or writing, respectively.
924 ssl_wants_io(int ssl_error)
926 return (ssl_error == SSL_ERROR_WANT_WRITE
927 || ssl_error == SSL_ERROR_WANT_READ);
933 static int init_status = -1;
934 if (init_status < 0) {
935 init_status = do_ssl_init();
936 ovs_assert(init_status >= 0);
947 /* The following call is needed if we "#include <openssl/applink.c>". */
948 CRYPTO_malloc_init();
951 SSL_load_error_strings();
953 if (!RAND_status()) {
954 /* We occasionally see OpenSSL fail to seed its random number generator
955 * in heavily loaded hypervisors. I suspect the following scenario:
957 * 1. OpenSSL calls read() to get 32 bytes from /dev/urandom.
958 * 2. The kernel generates 10 bytes of randomness and copies it out.
959 * 3. A signal arrives (perhaps SIGALRM).
960 * 4. The kernel interrupts the system call to service the signal.
961 * 5. Userspace gets 10 bytes of entropy.
962 * 6. OpenSSL doesn't read again to get the final 22 bytes. Therefore
963 * OpenSSL doesn't have enough entropy to consider itself
966 * The only part I'm not entirely sure about is #6, because the OpenSSL
967 * code is so hard to read. */
971 VLOG_WARN("OpenSSL random seeding failed, reseeding ourselves");
973 retval = get_entropy(seed, sizeof seed);
975 VLOG_ERR("failed to obtain entropy (%s)",
976 ovs_retval_to_string(retval));
977 return retval > 0 ? retval : ENOPROTOOPT;
980 RAND_seed(seed, sizeof seed);
983 /* OpenSSL has a bunch of "connection methods": SSLv2_method(),
984 * SSLv3_method(), TLSv1_method(), SSLv23_method(), ... Most of these
985 * support exactly one version of SSL, e.g. TLSv1_method() supports TLSv1
986 * only, not any earlier *or later* version. The only exception is
987 * SSLv23_method(), which in fact supports *any* version of SSL and TLS.
988 * We don't want SSLv2 or SSLv3 support, so we turn it off below with
989 * SSL_CTX_set_options().
991 * The cast is needed to avoid a warning with newer versions of OpenSSL in
992 * which SSLv23_method() returns a "const" pointer. */
993 method = CONST_CAST(SSL_METHOD *, SSLv23_method());
994 if (method == NULL) {
995 VLOG_ERR("TLSv1_method: %s", ERR_error_string(ERR_get_error(), NULL));
999 ctx = SSL_CTX_new(method);
1001 VLOG_ERR("SSL_CTX_new: %s", ERR_error_string(ERR_get_error(), NULL));
1004 SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
1005 SSL_CTX_set_tmp_dh_callback(ctx, tmp_dh_callback);
1006 SSL_CTX_set_mode(ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
1007 SSL_CTX_set_mode(ctx, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
1008 SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1015 tmp_dh_callback(SSL *ssl OVS_UNUSED, int is_export OVS_UNUSED, int keylength)
1020 DH *(*constructor)(void);
1023 static struct dh dh_table[] = {
1024 {1024, NULL, get_dh1024},
1025 {2048, NULL, get_dh2048},
1026 {4096, NULL, get_dh4096},
1031 for (dh = dh_table; dh < &dh_table[ARRAY_SIZE(dh_table)]; dh++) {
1032 if (dh->keylength == keylength) {
1034 dh->dh = dh->constructor();
1042 VLOG_ERR_RL(&rl, "no Diffie-Hellman parameters for key length %d",
1047 /* Returns true if SSL is at least partially configured. */
1049 stream_ssl_is_configured(void)
1051 return private_key.file_name || certificate.file_name || ca_cert.file_name;
1055 update_ssl_config(struct ssl_config_file *config, const char *file_name)
1057 struct timespec mtime;
1060 if (ssl_init() || !file_name) {
1064 /* If the file name hasn't changed and neither has the file contents, stop
1066 error = get_mtime(file_name, &mtime);
1067 if (error && error != ENOENT) {
1068 VLOG_ERR_RL(&rl, "%s: stat failed (%s)",
1069 file_name, ovs_strerror(error));
1071 if (config->file_name
1072 && !strcmp(config->file_name, file_name)
1073 && mtime.tv_sec == config->mtime.tv_sec
1074 && mtime.tv_nsec == config->mtime.tv_nsec) {
1078 /* Update 'config'. */
1079 config->mtime = mtime;
1080 if (file_name != config->file_name) {
1081 free(config->file_name);
1082 config->file_name = xstrdup(file_name);
1088 stream_ssl_set_private_key_file__(const char *file_name)
1090 if (SSL_CTX_use_PrivateKey_file(ctx, file_name, SSL_FILETYPE_PEM) == 1) {
1091 private_key.read = true;
1093 VLOG_ERR("SSL_use_PrivateKey_file: %s",
1094 ERR_error_string(ERR_get_error(), NULL));
1099 stream_ssl_set_private_key_file(const char *file_name)
1101 if (update_ssl_config(&private_key, file_name)) {
1102 stream_ssl_set_private_key_file__(file_name);
1107 stream_ssl_set_certificate_file__(const char *file_name)
1109 if (SSL_CTX_use_certificate_chain_file(ctx, file_name) == 1) {
1110 certificate.read = true;
1112 VLOG_ERR("SSL_use_certificate_file: %s",
1113 ERR_error_string(ERR_get_error(), NULL));
1118 stream_ssl_set_certificate_file(const char *file_name)
1120 if (update_ssl_config(&certificate, file_name)) {
1121 stream_ssl_set_certificate_file__(file_name);
1125 /* Sets the private key and certificate files in one operation. Use this
1126 * interface, instead of calling stream_ssl_set_private_key_file() and
1127 * stream_ssl_set_certificate_file() individually, in the main loop of a
1128 * long-running program whose key and certificate might change at runtime.
1130 * This is important because of OpenSSL's behavior. If an OpenSSL context
1131 * already has a certificate, and stream_ssl_set_private_key_file() is called
1132 * to install a new private key, OpenSSL will report an error because the new
1133 * private key does not match the old certificate. The other order, of setting
1134 * a new certificate, then setting a new private key, does work.
1136 * If this were the only problem, calling stream_ssl_set_certificate_file()
1137 * before stream_ssl_set_private_key_file() would fix it. But, if the private
1138 * key is changed before the certificate (e.g. someone "scp"s or "mv"s the new
1139 * private key in place before the certificate), then OpenSSL would reject that
1140 * change, and then the change of certificate would succeed, but there would be
1141 * no associated private key (because it had only changed once and therefore
1142 * there was no point in re-reading it).
1144 * This function avoids both problems by, whenever either the certificate or
1145 * the private key file changes, re-reading both of them, in the correct order.
1148 stream_ssl_set_key_and_cert(const char *private_key_file,
1149 const char *certificate_file)
1151 if (update_ssl_config(&private_key, private_key_file)
1152 || update_ssl_config(&certificate, certificate_file)) {
1153 stream_ssl_set_certificate_file__(certificate_file);
1154 stream_ssl_set_private_key_file__(private_key_file);
1158 /* Reads the X509 certificate or certificates in file 'file_name'. On success,
1159 * stores the address of the first element in an array of pointers to
1160 * certificates in '*certs' and the number of certificates in the array in
1161 * '*n_certs', and returns 0. On failure, stores a null pointer in '*certs', 0
1162 * in '*n_certs', and returns a positive errno value.
1164 * The caller is responsible for freeing '*certs'. */
1166 read_cert_file(const char *file_name, X509 ***certs, size_t *n_certs)
1169 size_t allocated_certs = 0;
1174 file = fopen(file_name, "r");
1176 VLOG_ERR("failed to open %s for reading: %s",
1177 file_name, ovs_strerror(errno));
1185 /* Read certificate from file. */
1186 certificate = PEM_read_X509(file, NULL, NULL, NULL);
1190 VLOG_ERR("PEM_read_X509 failed reading %s: %s",
1191 file_name, ERR_error_string(ERR_get_error(), NULL));
1192 for (i = 0; i < *n_certs; i++) {
1193 X509_free((*certs)[i]);
1201 /* Add certificate to array. */
1202 if (*n_certs >= allocated_certs) {
1203 *certs = x2nrealloc(*certs, &allocated_certs, sizeof **certs);
1205 (*certs)[(*n_certs)++] = certificate;
1207 /* Are there additional certificates in the file? */
1210 } while (isspace(c));
1221 /* Sets 'file_name' as the name of a file containing one or more X509
1222 * certificates to send to the peer. Typical use in OpenFlow is to send the CA
1223 * certificate to the peer, which enables a switch to pick up the controller's
1224 * CA certificate on its first connection. */
1226 stream_ssl_set_peer_ca_cert_file(const char *file_name)
1236 if (!read_cert_file(file_name, &certs, &n_certs)) {
1237 for (i = 0; i < n_certs; i++) {
1238 if (SSL_CTX_add_extra_chain_cert(ctx, certs[i]) != 1) {
1239 VLOG_ERR("SSL_CTX_add_extra_chain_cert: %s",
1240 ERR_error_string(ERR_get_error(), NULL));
1247 /* Logs fingerprint of CA certificate 'cert' obtained from 'file_name'. */
1249 log_ca_cert(const char *file_name, X509 *cert)
1251 unsigned char digest[EVP_MAX_MD_SIZE];
1252 unsigned int n_bytes;
1257 if (!X509_digest(cert, EVP_sha1(), digest, &n_bytes)) {
1258 ds_put_cstr(&fp, "<out of memory>");
1261 for (i = 0; i < n_bytes; i++) {
1263 ds_put_char(&fp, ':');
1265 ds_put_format(&fp, "%02x", digest[i]);
1268 subject = X509_NAME_oneline(X509_get_subject_name(cert), NULL, 0);
1269 VLOG_INFO("Trusting CA cert from %s (%s) (fingerprint %s)", file_name,
1270 subject ? subject : "<out of memory>", ds_cstr(&fp));
1271 OPENSSL_free(subject);
1276 stream_ssl_set_ca_cert_file__(const char *file_name,
1277 bool bootstrap, bool force)
1283 if (!update_ssl_config(&ca_cert, file_name) && !force) {
1287 if (!strcmp(file_name, "none")) {
1288 verify_peer_cert = false;
1289 VLOG_WARN("Peer certificate validation disabled "
1290 "(this is a security risk)");
1291 } else if (bootstrap && stat(file_name, &s) && errno == ENOENT) {
1292 bootstrap_ca_cert = true;
1293 } else if (!read_cert_file(file_name, &certs, &n_certs)) {
1296 /* Set up list of CAs that the server will accept from the client. */
1297 for (i = 0; i < n_certs; i++) {
1298 /* SSL_CTX_add_client_CA makes a copy of the relevant data. */
1299 if (SSL_CTX_add_client_CA(ctx, certs[i]) != 1) {
1300 VLOG_ERR("failed to add client certificate %"PRIuSIZE" from %s: %s",
1302 ERR_error_string(ERR_get_error(), NULL));
1304 log_ca_cert(file_name, certs[i]);
1306 X509_free(certs[i]);
1310 /* Set up CAs for OpenSSL to trust in verifying the peer's
1312 SSL_CTX_set_cert_store(ctx, X509_STORE_new());
1313 if (SSL_CTX_load_verify_locations(ctx, file_name, NULL) != 1) {
1314 VLOG_ERR("SSL_CTX_load_verify_locations: %s",
1315 ERR_error_string(ERR_get_error(), NULL));
1319 bootstrap_ca_cert = false;
1321 ca_cert.read = true;
1324 /* Sets 'file_name' as the name of the file from which to read the CA
1325 * certificate used to verify the peer within SSL connections. If 'bootstrap'
1326 * is false, the file must exist. If 'bootstrap' is false, then the file is
1327 * read if it is exists; if it does not, then it will be created from the CA
1328 * certificate received from the peer on the first SSL connection. */
1330 stream_ssl_set_ca_cert_file(const char *file_name, bool bootstrap)
1332 stream_ssl_set_ca_cert_file__(file_name, bootstrap, false);
1335 /* SSL protocol logging. */
1338 ssl_alert_level_to_string(uint8_t type)
1341 case 1: return "warning";
1342 case 2: return "fatal";
1343 default: return "<unknown>";
1348 ssl_alert_description_to_string(uint8_t type)
1351 case 0: return "close_notify";
1352 case 10: return "unexpected_message";
1353 case 20: return "bad_record_mac";
1354 case 21: return "decryption_failed";
1355 case 22: return "record_overflow";
1356 case 30: return "decompression_failure";
1357 case 40: return "handshake_failure";
1358 case 42: return "bad_certificate";
1359 case 43: return "unsupported_certificate";
1360 case 44: return "certificate_revoked";
1361 case 45: return "certificate_expired";
1362 case 46: return "certificate_unknown";
1363 case 47: return "illegal_parameter";
1364 case 48: return "unknown_ca";
1365 case 49: return "access_denied";
1366 case 50: return "decode_error";
1367 case 51: return "decrypt_error";
1368 case 60: return "export_restriction";
1369 case 70: return "protocol_version";
1370 case 71: return "insufficient_security";
1371 case 80: return "internal_error";
1372 case 90: return "user_canceled";
1373 case 100: return "no_renegotiation";
1374 default: return "<unknown>";
1379 ssl_handshake_type_to_string(uint8_t type)
1382 case 0: return "hello_request";
1383 case 1: return "client_hello";
1384 case 2: return "server_hello";
1385 case 11: return "certificate";
1386 case 12: return "server_key_exchange";
1387 case 13: return "certificate_request";
1388 case 14: return "server_hello_done";
1389 case 15: return "certificate_verify";
1390 case 16: return "client_key_exchange";
1391 case 20: return "finished";
1392 default: return "<unknown>";
1397 ssl_protocol_cb(int write_p, int version OVS_UNUSED, int content_type,
1398 const void *buf_, size_t len, SSL *ssl OVS_UNUSED, void *sslv_)
1400 const struct ssl_stream *sslv = sslv_;
1401 const uint8_t *buf = buf_;
1404 if (!VLOG_IS_DBG_ENABLED()) {
1409 if (content_type == 20) {
1410 ds_put_cstr(&details, "change_cipher_spec");
1411 } else if (content_type == 21) {
1412 ds_put_format(&details, "alert: %s, %s",
1413 ssl_alert_level_to_string(buf[0]),
1414 ssl_alert_description_to_string(buf[1]));
1415 } else if (content_type == 22) {
1416 ds_put_format(&details, "handshake: %s",
1417 ssl_handshake_type_to_string(buf[0]));
1419 ds_put_format(&details, "type %d", content_type);
1422 VLOG_DBG("%s%u%s%s %s (%"PRIuSIZE" bytes)",
1423 sslv->type == CLIENT ? "client" : "server",
1424 sslv->session_nr, write_p ? "-->" : "<--",
1425 stream_get_name(&sslv->stream), ds_cstr(&details), len);
1427 ds_destroy(&details);
1431 clear_handle(int fd OVS_UNUSED, HANDLE wevent OVS_UNUSED)
1435 WSAEventSelect(fd, NULL, 0);
1438 CloseHandle(wevent);