1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
9 library. It is #included into the tls.c file when that library is used. The
10 code herein is based on a patch that was originally contributed by Steve
11 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
13 No cryptographic code is included in Exim. All this module does is to call
14 functions from the OpenSSL library. */
19 #include <openssl/lhash.h>
20 #include <openssl/ssl.h>
21 #include <openssl/err.h>
22 #include <openssl/rand.h>
23 #ifdef EXPERIMENTAL_OCSP
24 #include <openssl/ocsp.h>
27 #ifdef EXPERIMENTAL_OCSP
28 #define EXIM_OCSP_SKEW_SECONDS (300L)
29 #define EXIM_OCSP_MAX_AGE (-1L)
32 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
33 #define EXIM_HAVE_OPENSSL_TLSEXT
36 /* Structure for collecting random data for seeding. */
38 typedef struct randstuff {
43 /* Local static variables */
45 static BOOL verify_callback_called = FALSE;
46 static const uschar *sid_ctx = US"exim";
48 static SSL_CTX *ctx = NULL;
49 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
50 static SSL_CTX *ctx_sni = NULL;
52 static SSL *ssl = NULL;
54 static char ssl_errstring[256];
56 static int ssl_session_timeout = 200;
57 static BOOL verify_optional = FALSE;
59 static BOOL reexpand_tls_files_for_sni = FALSE;
62 typedef struct tls_ext_ctx_cb {
65 #ifdef EXPERIMENTAL_OCSP
67 uschar *ocsp_file_expanded;
68 OCSP_RESPONSE *ocsp_response;
71 /* these are cached from first expand */
72 uschar *server_cipher_list;
73 /* only passed down to tls_error: */
77 /* should figure out a cleanup of API to handle state preserved per
78 implementation, for various reasons, which can be void * in the APIs.
79 For now, we hack around it. */
80 tls_ext_ctx_cb *static_cbinfo = NULL;
83 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional);
86 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
87 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
89 #ifdef EXPERIMENTAL_OCSP
90 static int tls_stapling_cb(SSL *s, void *arg);
94 /*************************************************
96 *************************************************/
98 /* Called from lots of places when errors occur before actually starting to do
99 the TLS handshake, that is, while the session is still in clear. Always returns
100 DEFER for a server and FAIL for a client so that most calls can use "return
101 tls_error(...)" to do this processing and then give an appropriate return. A
102 single function is used for both server and client, because it is called from
103 some shared functions.
106 prefix text to include in the logged error
107 host NULL if setting up a server;
108 the connected host if setting up a client
109 msg error message or NULL if we should ask OpenSSL
111 Returns: OK/DEFER/FAIL
115 tls_error(uschar *prefix, host_item *host, uschar *msg)
119 ERR_error_string(ERR_get_error(), ssl_errstring);
120 msg = (uschar *)ssl_errstring;
125 uschar *conn_info = smtp_get_connection_info();
126 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
128 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
129 conn_info, prefix, msg);
134 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
135 host->name, host->address, prefix, msg);
142 /*************************************************
143 * Callback to generate RSA key *
144 *************************************************/
152 Returns: pointer to generated key
156 rsa_callback(SSL *s, int export, int keylength)
159 export = export; /* Shut picky compilers up */
160 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
161 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
164 ERR_error_string(ERR_get_error(), ssl_errstring);
165 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
175 /*************************************************
176 * Callback for verification *
177 *************************************************/
179 /* The SSL library does certificate verification if set up to do so. This
180 callback has the current yes/no state is in "state". If verification succeeded,
181 we set up the tls_peerdn string. If verification failed, what happens depends
182 on whether the client is required to present a verifiable certificate or not.
184 If verification is optional, we change the state to yes, but still log the
185 verification error. For some reason (it really would help to have proper
186 documentation of OpenSSL), this callback function then gets called again, this
187 time with state = 1. In fact, that's useful, because we can set up the peerdn
188 value, but we must take care not to set the private verified flag on the second
191 Note: this function is not called if the client fails to present a certificate
192 when asked. We get here only if a certificate has been received. Handling of
193 optional verification for this case is done when requesting SSL to verify, by
194 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
197 state current yes/no state as 1/0
198 x509ctx certificate information.
200 Returns: 1 if verified, 0 if not
204 verify_callback(int state, X509_STORE_CTX *x509ctx)
206 static uschar txt[256];
208 X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert),
209 CS txt, sizeof(txt));
213 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
214 x509ctx->error_depth,
215 X509_verify_cert_error_string(x509ctx->error),
217 tls_certificate_verified = FALSE;
218 verify_callback_called = TRUE;
219 if (!verify_optional) return 0; /* reject */
220 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
221 "tls_try_verify_hosts)\n");
222 return 1; /* accept */
225 if (x509ctx->error_depth != 0)
227 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n",
228 x509ctx->error_depth, txt);
232 DEBUG(D_tls) debug_printf("SSL%s peer: %s\n",
233 verify_callback_called? "" : " authenticated", txt);
237 if (!verify_callback_called) tls_certificate_verified = TRUE;
238 verify_callback_called = TRUE;
240 return 1; /* accept */
245 /*************************************************
246 * Information callback *
247 *************************************************/
249 /* The SSL library functions call this from time to time to indicate what they
250 are doing. We copy the string to the debugging output when TLS debugging has
262 info_callback(SSL *s, int where, int ret)
266 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
271 /*************************************************
272 * Initialize for DH *
273 *************************************************/
275 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
278 dhparam DH parameter file or fixed parameter identity string
279 host connected host, if client; NULL if server
281 Returns: TRUE if OK (nothing to set up, or setup worked)
285 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
292 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
295 if (dhexpanded == NULL || *dhexpanded == '\0')
297 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
299 else if (dhexpanded[0] == '/')
301 bio = BIO_new_file(CS dhexpanded, "r");
304 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
305 host, US strerror(errno));
311 if (Ustrcmp(dhexpanded, "none") == 0)
313 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
317 pem = std_dh_prime_named(dhexpanded);
320 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
321 host, US strerror(errno));
324 bio = BIO_new_mem_buf(CS pem, -1);
327 dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
331 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
336 /* Even if it is larger, we silently return success rather than cause things
337 * to fail out, so that a too-large DH will not knock out all TLS; it's a
338 * debatable choice. */
339 if ((8*DH_size(dh)) > tls_dh_max_bits)
342 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
343 8*DH_size(dh), tls_dh_max_bits);
347 SSL_CTX_set_tmp_dh(sctx, dh);
349 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
350 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
362 #ifdef EXPERIMENTAL_OCSP
363 /*************************************************
364 * Load OCSP information into state *
365 *************************************************/
367 /* Called to load the OCSP response from the given file into memory, once
368 caller has determined this is needed. Checks validity. Debugs a message
371 ASSUMES: single response, for single cert.
374 sctx the SSL_CTX* to update
375 cbinfo various parts of session state
376 expanded the filename putatively holding an OCSP response
381 ocsp_load_response(SSL_CTX *sctx,
382 tls_ext_ctx_cb *cbinfo,
383 const uschar *expanded)
387 OCSP_BASICRESP *basic_response;
388 OCSP_SINGLERESP *single_response;
389 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
391 unsigned long verify_flags;
392 int status, reason, i;
394 cbinfo->ocsp_file_expanded = string_copy(expanded);
395 if (cbinfo->ocsp_response)
397 OCSP_RESPONSE_free(cbinfo->ocsp_response);
398 cbinfo->ocsp_response = NULL;
401 bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb");
404 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
405 cbinfo->ocsp_file_expanded);
409 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
413 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
417 status = OCSP_response_status(resp);
418 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
420 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
421 OCSP_response_status_str(status), status);
425 basic_response = OCSP_response_get1_basic(resp);
429 debug_printf("OCSP response parse error: unable to extract basic response.\n");
433 store = SSL_CTX_get_cert_store(sctx);
434 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
436 /* May need to expose ability to adjust those flags?
437 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
438 OCSP_TRUSTOTHER OCSP_NOINTERN */
440 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
444 ERR_error_string(ERR_get_error(), ssl_errstring);
445 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
450 /* Here's the simplifying assumption: there's only one response, for the
451 one certificate we use, and nothing for anything else in a chain. If this
452 proves false, we need to extract a cert id from our issued cert
453 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
454 right cert in the stack and then calls OCSP_single_get0_status()).
456 I'm hoping to avoid reworking a bunch more of how we handle state here. */
457 single_response = OCSP_resp_get0(basic_response, 0);
458 if (!single_response)
461 debug_printf("Unable to get first response from OCSP basic response.\n");
465 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
466 /* how does this status differ from the one above? */
467 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
469 DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n",
470 OCSP_response_status_str(status), status);
474 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
476 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
480 cbinfo->ocsp_response = resp;
487 /*************************************************
488 * Expand key and cert file specs *
489 *************************************************/
491 /* Called once during tls_init and possibly againt during TLS setup, for a
492 new context, if Server Name Indication was used and tls_sni was seen in
493 the certificate string.
496 sctx the SSL_CTX* to update
497 cbinfo various parts of session state
499 Returns: OK/DEFER/FAIL
503 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
507 if (cbinfo->certificate == NULL)
510 if (Ustrstr(cbinfo->certificate, US"tls_sni"))
511 reexpand_tls_files_for_sni = TRUE;
513 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
516 if (expanded != NULL)
518 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
519 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
520 return tls_error(string_sprintf(
521 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
525 if (cbinfo->privatekey != NULL &&
526 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
529 /* If expansion was forced to fail, key_expanded will be NULL. If the result
530 of the expansion is an empty string, ignore it also, and assume the private
531 key is in the same file as the certificate. */
533 if (expanded != NULL && *expanded != 0)
535 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
536 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
537 return tls_error(string_sprintf(
538 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
541 #ifdef EXPERIMENTAL_OCSP
542 if (cbinfo->ocsp_file != NULL)
544 if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded))
547 if (expanded != NULL && *expanded != 0)
549 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
550 if (cbinfo->ocsp_file_expanded &&
551 (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0))
554 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
556 ocsp_load_response(sctx, cbinfo, expanded);
568 /*************************************************
569 * Callback to handle SNI *
570 *************************************************/
572 /* Called when acting as server during the TLS session setup if a Server Name
573 Indication extension was sent by the client.
575 API documentation is OpenSSL s_server.c implementation.
578 s SSL* of the current session
579 ad unknown (part of OpenSSL API) (unused)
580 arg Callback of "our" registered data
582 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
585 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
587 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
589 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
590 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
592 int old_pool = store_pool;
595 return SSL_TLSEXT_ERR_OK;
597 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
598 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
600 /* Make the extension value available for expansion */
601 store_pool = POOL_PERM;
602 tls_sni = string_copy(US servername);
603 store_pool = old_pool;
605 if (!reexpand_tls_files_for_sni)
606 return SSL_TLSEXT_ERR_OK;
608 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
609 not confident that memcpy wouldn't break some internal reference counting.
610 Especially since there's a references struct member, which would be off. */
612 ctx_sni = SSL_CTX_new(SSLv23_server_method());
615 ERR_error_string(ERR_get_error(), ssl_errstring);
616 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
617 return SSL_TLSEXT_ERR_NOACK;
620 /* Not sure how many of these are actually needed, since SSL object
621 already exists. Might even need this selfsame callback, for reneg? */
623 SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx));
624 SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx));
625 SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx));
626 SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx));
627 SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb);
628 SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo);
629 if (cbinfo->server_cipher_list)
630 SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list);
631 #ifdef EXPERIMENTAL_OCSP
632 if (cbinfo->ocsp_file)
634 SSL_CTX_set_tlsext_status_cb(ctx_sni, tls_stapling_cb);
635 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
639 rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE);
640 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
642 /* do this after setup_certs, because this can require the certs for verifying
644 rc = tls_expand_session_files(ctx_sni, cbinfo);
645 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
647 rc = init_dh(ctx_sni, cbinfo->dhparam, NULL);
648 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
650 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
651 SSL_set_SSL_CTX(s, ctx_sni);
653 return SSL_TLSEXT_ERR_OK;
655 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
660 #ifdef EXPERIMENTAL_OCSP
661 /*************************************************
662 * Callback to handle OCSP Stapling *
663 *************************************************/
665 /* Called when acting as server during the TLS session setup if the client
666 requests OCSP information with a Certificate Status Request.
668 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
674 tls_stapling_cb(SSL *s, void *arg)
676 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
677 uschar *response_der;
678 int response_der_len;
680 DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n",
681 cbinfo->ocsp_response ? "have" : "lack");
682 if (!cbinfo->ocsp_response)
683 return SSL_TLSEXT_ERR_NOACK;
686 response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der);
687 if (response_der_len <= 0)
688 return SSL_TLSEXT_ERR_NOACK;
690 SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len);
691 return SSL_TLSEXT_ERR_OK;
694 #endif /* EXPERIMENTAL_OCSP */
699 /*************************************************
700 * Initialize for TLS *
701 *************************************************/
703 /* Called from both server and client code, to do preliminary initialization of
707 host connected host, if client; NULL if server
708 dhparam DH parameter file
709 certificate certificate file
710 privatekey private key
711 addr address if client; NULL if server (for some randomness)
713 Returns: OK/DEFER/FAIL
717 tls_init(host_item *host, uschar *dhparam, uschar *certificate,
719 #ifdef EXPERIMENTAL_OCSP
727 tls_ext_ctx_cb *cbinfo;
729 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
730 cbinfo->certificate = certificate;
731 cbinfo->privatekey = privatekey;
732 #ifdef EXPERIMENTAL_OCSP
733 cbinfo->ocsp_file = ocsp_file;
735 cbinfo->dhparam = dhparam;
738 SSL_load_error_strings(); /* basic set up */
739 OpenSSL_add_ssl_algorithms();
741 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
742 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
743 list of available digests. */
744 EVP_add_digest(EVP_sha256());
748 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
749 negotiation in the different methods; as far as I can tell, the only
750 *_{server,client}_method which allows negotiation is SSLv23, which exists even
751 when OpenSSL is built without SSLv2 support.
752 By disabling with openssl_options, we can let admins re-enable with the
755 ctx = SSL_CTX_new((host == NULL)?
756 SSLv23_server_method() : SSLv23_client_method());
758 if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
760 /* It turns out that we need to seed the random number generator this early in
761 order to get the full complement of ciphers to work. It took me roughly a day
762 of work to discover this by experiment.
764 On systems that have /dev/urandom, SSL may automatically seed itself from
765 there. Otherwise, we have to make something up as best we can. Double check
771 gettimeofday(&r.tv, NULL);
774 RAND_seed((uschar *)(&r), sizeof(r));
775 RAND_seed((uschar *)big_buffer, big_buffer_size);
776 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
779 return tls_error(US"RAND_status", host,
780 US"unable to seed random number generator");
783 /* Set up the information callback, which outputs if debugging is at a suitable
786 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
788 /* Automatically re-try reads/writes after renegotiation. */
789 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
791 /* Apply administrator-supplied work-arounds.
792 Historically we applied just one requested option,
793 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
794 moved to an administrator-controlled list of options to specify and
795 grandfathered in the first one as the default value for "openssl_options".
797 No OpenSSL version number checks: the options we accept depend upon the
798 availability of the option value macros from OpenSSL. */
800 okay = tls_openssl_options_parse(openssl_options, &init_options);
802 return tls_error(US"openssl_options parsing failed", host, NULL);
806 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
807 if (!(SSL_CTX_set_options(ctx, init_options)))
808 return tls_error(string_sprintf(
809 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
812 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
814 /* Initialize with DH parameters if supplied */
816 if (!init_dh(ctx, dhparam, host)) return DEFER;
818 /* Set up certificate and key (and perhaps OCSP info) */
820 rc = tls_expand_session_files(ctx, cbinfo);
821 if (rc != OK) return rc;
823 /* If we need to handle SNI, do so */
824 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
827 #ifdef EXPERIMENTAL_OCSP
828 /* We check ocsp_file, not ocsp_response, because we care about if
829 the option exists, not what the current expansion might be, as SNI might
830 change the certificate and OCSP file in use between now and the time the
831 callback is invoked. */
832 if (cbinfo->ocsp_file)
834 SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb);
835 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
838 /* We always do this, so that $tls_sni is available even if not used in
840 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
841 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
845 /* Set up the RSA callback */
847 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
849 /* Finally, set the timeout, and we are done */
851 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
852 DEBUG(D_tls) debug_printf("Initialized TLS\n");
854 static_cbinfo = cbinfo;
862 /*************************************************
863 * Get name of cipher in use *
864 *************************************************/
866 /* The answer is left in a static buffer, and tls_cipher is set to point
869 Argument: pointer to an SSL structure for the connection
874 construct_cipher_name(SSL *ssl)
876 static uschar cipherbuf[256];
877 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
878 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
879 the accessor functions use const in the prototype. */
883 switch (ssl->session->ssl_version)
897 #ifdef TLS1_1_VERSION
903 #ifdef TLS1_2_VERSION
913 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
914 SSL_CIPHER_get_bits(c, &tls_bits);
916 string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
917 SSL_CIPHER_get_name(c), tls_bits);
918 tls_cipher = cipherbuf;
920 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
927 /*************************************************
928 * Set up for verifying certificates *
929 *************************************************/
931 /* Called by both client and server startup
934 sctx SSL_CTX* to initialise
935 certs certs file or NULL
937 host NULL in a server; the remote host in a client
938 optional TRUE if called from a server for a host in tls_try_verify_hosts;
939 otherwise passed as FALSE
941 Returns: OK/DEFER/FAIL
945 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional)
947 uschar *expcerts, *expcrl;
949 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
952 if (expcerts != NULL)
955 if (!SSL_CTX_set_default_verify_paths(sctx))
956 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
958 if (Ustat(expcerts, &statbuf) < 0)
960 log_write(0, LOG_MAIN|LOG_PANIC,
961 "failed to stat %s for certificates", expcerts);
967 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
968 { file = NULL; dir = expcerts; }
970 { file = expcerts; dir = NULL; }
972 /* If a certificate file is empty, the next function fails with an
973 unhelpful error message. If we skip it, we get the correct behaviour (no
974 certificates are recognized, but the error message is still misleading (it
975 says no certificate was supplied.) But this is better. */
977 if ((file == NULL || statbuf.st_size > 0) &&
978 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
979 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
983 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
987 /* Handle a certificate revocation list. */
989 #if OPENSSL_VERSION_NUMBER > 0x00907000L
991 /* This bit of code is now the version supplied by Lars Mainka. (I have
992 * merely reformatted it into the Exim code style.)
994 * "From here I changed the code to add support for multiple crl's
995 * in pem format in one file or to support hashed directory entries in
996 * pem format instead of a file. This method now uses the library function
997 * X509_STORE_load_locations to add the CRL location to the SSL context.
998 * OpenSSL will then handle the verify against CA certs and CRLs by
999 * itself in the verify callback." */
1001 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1002 if (expcrl != NULL && *expcrl != 0)
1004 struct stat statbufcrl;
1005 if (Ustat(expcrl, &statbufcrl) < 0)
1007 log_write(0, LOG_MAIN|LOG_PANIC,
1008 "failed to stat %s for certificates revocation lists", expcrl);
1013 /* is it a file or directory? */
1015 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1016 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1020 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1026 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1028 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1029 return tls_error(US"X509_STORE_load_locations", host, NULL);
1031 /* setting the flags to check against the complete crl chain */
1033 X509_STORE_set_flags(cvstore,
1034 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1038 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1040 /* If verification is optional, don't fail if no certificate */
1042 SSL_CTX_set_verify(sctx,
1043 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1052 /*************************************************
1053 * Start a TLS session in a server *
1054 *************************************************/
1056 /* This is called when Exim is running as a server, after having received
1057 the STARTTLS command. It must respond to that command, and then negotiate
1061 require_ciphers allowed ciphers
1063 Returns: OK on success
1064 DEFER for errors before the start of the negotiation
1065 FAIL for errors during the negotation; the server can't
1070 tls_server_start(const uschar *require_ciphers)
1074 tls_ext_ctx_cb *cbinfo;
1076 /* Check for previous activation */
1078 if (tls_active >= 0)
1080 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1081 smtp_printf("554 Already in TLS\r\n");
1085 /* Initialize the SSL library. If it fails, it will already have logged
1088 rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey,
1089 #ifdef EXPERIMENTAL_OCSP
1093 if (rc != OK) return rc;
1094 cbinfo = static_cbinfo;
1096 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1099 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1100 were historically separated by underscores. So that I can use either form in my
1101 tests, and also for general convenience, we turn underscores into hyphens here.
1104 if (expciphers != NULL)
1106 uschar *s = expciphers;
1107 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1108 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1109 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1110 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1111 cbinfo->server_cipher_list = expciphers;
1114 /* If this is a host for which certificate verification is mandatory or
1115 optional, set up appropriately. */
1117 tls_certificate_verified = FALSE;
1118 verify_callback_called = FALSE;
1120 if (verify_check_host(&tls_verify_hosts) == OK)
1122 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE);
1123 if (rc != OK) return rc;
1124 verify_optional = FALSE;
1126 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1128 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE);
1129 if (rc != OK) return rc;
1130 verify_optional = TRUE;
1133 /* Prepare for new connection */
1135 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1137 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1139 * With the SSL_clear(), we get strange interoperability bugs with
1140 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1141 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1143 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1144 * session shutdown. In this case, we have a brand new object and there's no
1145 * obvious reason to immediately clear it. I'm guessing that this was
1146 * originally added because of incomplete initialisation which the clear fixed,
1147 * in some historic release.
1150 /* Set context and tell client to go ahead, except in the case of TLS startup
1151 on connection, where outputting anything now upsets the clients and tends to
1152 make them disconnect. We need to have an explicit fflush() here, to force out
1153 the response. Other smtp_printf() calls do not need it, because in non-TLS
1154 mode, the fflush() happens when smtp_getc() is called. */
1156 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1157 if (!tls_on_connect)
1159 smtp_printf("220 TLS go ahead\r\n");
1163 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1164 that the OpenSSL library doesn't. */
1166 SSL_set_wfd(ssl, fileno(smtp_out));
1167 SSL_set_rfd(ssl, fileno(smtp_in));
1168 SSL_set_accept_state(ssl);
1170 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1172 sigalrm_seen = FALSE;
1173 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1174 rc = SSL_accept(ssl);
1179 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1180 if (ERR_get_error() == 0)
1181 log_write(0, LOG_MAIN,
1182 "TLS client disconnected cleanly (rejected our certificate?)");
1186 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1188 /* TLS has been set up. Adjust the input functions to read via TLS,
1189 and initialize things. */
1191 construct_cipher_name(ssl);
1196 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL)
1197 debug_printf("Shared ciphers: %s\n", buf);
1201 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1202 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1203 ssl_xfer_eof = ssl_xfer_error = 0;
1205 receive_getc = tls_getc;
1206 receive_ungetc = tls_ungetc;
1207 receive_feof = tls_feof;
1208 receive_ferror = tls_ferror;
1209 receive_smtp_buffered = tls_smtp_buffered;
1211 tls_active = fileno(smtp_out);
1219 /*************************************************
1220 * Start a TLS session in a client *
1221 *************************************************/
1223 /* Called from the smtp transport after STARTTLS has been accepted.
1226 fd the fd of the connection
1227 host connected host (for messages)
1228 addr the first address
1229 dhparam DH parameter file
1230 certificate certificate file
1231 privatekey private key file
1232 sni TLS SNI to send to remote host
1233 verify_certs file for certificate verify
1234 crl file containing CRL
1235 require_ciphers list of allowed ciphers
1236 dh_min_bits minimum number of bits acceptable in server's DH prime
1238 timeout startup timeout
1240 Returns: OK on success
1241 FAIL otherwise - note that tls_error() will not give DEFER
1242 because this is not a server
1246 tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
1247 uschar *certificate, uschar *privatekey, uschar *sni,
1248 uschar *verify_certs, uschar *crl,
1249 uschar *require_ciphers, int dh_min_bits ARG_UNUSED, int timeout)
1251 static uschar txt[256];
1256 rc = tls_init(host, dhparam, certificate, privatekey,
1257 #ifdef EXPERIMENTAL_OCSP
1261 if (rc != OK) return rc;
1263 tls_certificate_verified = FALSE;
1264 verify_callback_called = FALSE;
1266 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1269 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1270 are separated by underscores. So that I can use either form in my tests, and
1271 also for general convenience, we turn underscores into hyphens here. */
1273 if (expciphers != NULL)
1275 uschar *s = expciphers;
1276 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1277 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1278 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1279 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1282 rc = setup_certs(ctx, verify_certs, crl, host, FALSE);
1283 if (rc != OK) return rc;
1285 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1286 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1287 SSL_set_fd(ssl, fd);
1288 SSL_set_connect_state(ssl);
1292 if (!expand_check(sni, US"tls_sni", &tls_sni))
1294 if (!Ustrlen(tls_sni))
1298 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1299 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni);
1300 SSL_set_tlsext_host_name(ssl, tls_sni);
1303 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1309 /* There doesn't seem to be a built-in timeout on connection. */
1311 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1312 sigalrm_seen = FALSE;
1314 rc = SSL_connect(ssl);
1318 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1320 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1322 /* Beware anonymous ciphers which lead to server_cert being NULL */
1323 server_cert = SSL_get_peer_certificate (ssl);
1326 tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1327 CS txt, sizeof(txt));
1333 construct_cipher_name(ssl); /* Sets tls_cipher */
1343 /*************************************************
1344 * TLS version of getc *
1345 *************************************************/
1347 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1348 it refills the buffer via the SSL reading function.
1351 Returns: the next character or EOF
1357 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1362 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1363 ssl_xfer_buffer, ssl_xfer_buffer_size);
1365 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1366 inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1367 error = SSL_get_error(ssl, inbytes);
1370 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1371 closed down, not that the socket itself has been closed down. Revert to
1372 non-SSL handling. */
1374 if (error == SSL_ERROR_ZERO_RETURN)
1376 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1378 receive_getc = smtp_getc;
1379 receive_ungetc = smtp_ungetc;
1380 receive_feof = smtp_feof;
1381 receive_ferror = smtp_ferror;
1382 receive_smtp_buffered = smtp_buffered;
1395 /* Handle genuine errors */
1397 else if (error == SSL_ERROR_SSL)
1399 ERR_error_string(ERR_get_error(), ssl_errstring);
1400 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
1405 else if (error != SSL_ERROR_NONE)
1407 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1412 #ifndef DISABLE_DKIM
1413 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1415 ssl_xfer_buffer_hwm = inbytes;
1416 ssl_xfer_buffer_lwm = 0;
1419 /* Something in the buffer; return next uschar */
1421 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1426 /*************************************************
1427 * Read bytes from TLS channel *
1428 *************************************************/
1435 Returns: the number of bytes read
1436 -1 after a failed read
1440 tls_read(uschar *buff, size_t len)
1445 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1446 buff, (unsigned int)len);
1448 inbytes = SSL_read(ssl, CS buff, len);
1449 error = SSL_get_error(ssl, inbytes);
1451 if (error == SSL_ERROR_ZERO_RETURN)
1453 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1456 else if (error != SSL_ERROR_NONE)
1468 /*************************************************
1469 * Write bytes down TLS channel *
1470 *************************************************/
1477 Returns: the number of bytes after a successful write,
1478 -1 after a failed write
1482 tls_write(const uschar *buff, size_t len)
1488 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
1491 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
1492 outbytes = SSL_write(ssl, CS buff, left);
1493 error = SSL_get_error(ssl, outbytes);
1494 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1498 ERR_error_string(ERR_get_error(), ssl_errstring);
1499 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1502 case SSL_ERROR_NONE:
1507 case SSL_ERROR_ZERO_RETURN:
1508 log_write(0, LOG_MAIN, "SSL channel closed on write");
1512 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1521 /*************************************************
1522 * Close down a TLS session *
1523 *************************************************/
1525 /* This is also called from within a delivery subprocess forked from the
1526 daemon, to shut down the TLS library, without actually doing a shutdown (which
1527 would tamper with the SSL session in the parent process).
1529 Arguments: TRUE if SSL_shutdown is to be called
1534 tls_close(BOOL shutdown)
1536 if (tls_active < 0) return; /* TLS was not active */
1540 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
1553 /*************************************************
1554 * Let tls_require_ciphers be checked at startup *
1555 *************************************************/
1557 /* The tls_require_ciphers option, if set, must be something which the
1560 Returns: NULL on success, or error message
1564 tls_validate_require_cipher(void)
1567 uschar *s, *expciphers, *err;
1569 /* this duplicates from tls_init(), we need a better "init just global
1570 state, for no specific purpose" singleton function of our own */
1572 SSL_load_error_strings();
1573 OpenSSL_add_ssl_algorithms();
1574 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1575 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1576 list of available digests. */
1577 EVP_add_digest(EVP_sha256());
1580 if (!(tls_require_ciphers && *tls_require_ciphers))
1583 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1584 return US"failed to expand tls_require_ciphers";
1586 if (!(expciphers && *expciphers))
1589 /* normalisation ripped from above */
1591 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1595 ctx = SSL_CTX_new(SSLv23_server_method());
1598 ERR_error_string(ERR_get_error(), ssl_errstring);
1599 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1603 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1605 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1607 ERR_error_string(ERR_get_error(), ssl_errstring);
1608 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1619 /*************************************************
1620 * Report the library versions. *
1621 *************************************************/
1623 /* There have historically been some issues with binary compatibility in
1624 OpenSSL libraries; if Exim (like many other applications) is built against
1625 one version of OpenSSL but the run-time linker picks up another version,
1626 it can result in serious failures, including crashing with a SIGSEGV. So
1627 report the version found by the compiler and the run-time version.
1629 Arguments: a FILE* to print the results to
1634 tls_version_report(FILE *f)
1636 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1638 OPENSSL_VERSION_TEXT,
1639 SSLeay_version(SSLEAY_VERSION));
1645 /*************************************************
1646 * Random number generation *
1647 *************************************************/
1649 /* Pseudo-random number generation. The result is not expected to be
1650 cryptographically strong but not so weak that someone will shoot themselves
1651 in the foot using it as a nonce in input in some email header scheme or
1652 whatever weirdness they'll twist this into. The result should handle fork()
1653 and avoid repeating sequences. OpenSSL handles that for us.
1657 Returns a random number in range [0, max-1]
1661 vaguely_random_number(int max)
1666 uschar smallbuf[sizeof(r)];
1671 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1675 gettimeofday(&r.tv, NULL);
1678 RAND_seed((uschar *)(&r), sizeof(r));
1680 /* We're after pseudo-random, not random; if we still don't have enough data
1681 in the internal PRNG then our options are limited. We could sleep and hope
1682 for entropy to come along (prayer technique) but if the system is so depleted
1683 in the first place then something is likely to just keep taking it. Instead,
1684 we'll just take whatever little bit of pseudo-random we can still manage to
1687 needed_len = sizeof(r);
1688 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1689 asked for a number less than 10. */
1690 for (r = max, i = 0; r; ++i)
1696 /* We do not care if crypto-strong */
1697 i = RAND_pseudo_bytes(smallbuf, needed_len);
1701 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
1702 return vaguely_random_number_fallback(max);
1706 for (p = smallbuf; needed_len; --needed_len, ++p)
1712 /* We don't particularly care about weighted results; if someone wants
1713 smooth distribution and cares enough then they should submit a patch then. */
1720 /*************************************************
1721 * OpenSSL option parse *
1722 *************************************************/
1724 /* Parse one option for tls_openssl_options_parse below
1727 name one option name
1728 value place to store a value for it
1729 Returns success or failure in parsing
1732 struct exim_openssl_option {
1736 /* We could use a macro to expand, but we need the ifdef and not all the
1737 options document which version they were introduced in. Policylet: include
1738 all options unless explicitly for DTLS, let the administrator choose which
1741 This list is current as of:
1743 static struct exim_openssl_option exim_openssl_options[] = {
1744 /* KEEP SORTED ALPHABETICALLY! */
1746 { US"all", SSL_OP_ALL },
1748 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
1749 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
1751 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
1752 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
1754 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1755 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
1757 #ifdef SSL_OP_EPHEMERAL_RSA
1758 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
1760 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
1761 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
1763 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
1764 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
1766 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
1767 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
1769 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
1770 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
1772 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
1773 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
1775 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
1776 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
1778 #ifdef SSL_OP_NO_COMPRESSION
1779 { US"no_compression", SSL_OP_NO_COMPRESSION },
1781 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
1782 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
1784 #ifdef SSL_OP_NO_SSLv2
1785 { US"no_sslv2", SSL_OP_NO_SSLv2 },
1787 #ifdef SSL_OP_NO_SSLv3
1788 { US"no_sslv3", SSL_OP_NO_SSLv3 },
1790 #ifdef SSL_OP_NO_TICKET
1791 { US"no_ticket", SSL_OP_NO_TICKET },
1793 #ifdef SSL_OP_NO_TLSv1
1794 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
1796 #ifdef SSL_OP_NO_TLSv1_1
1797 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
1798 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
1799 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
1801 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
1804 #ifdef SSL_OP_NO_TLSv1_2
1805 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
1807 #ifdef SSL_OP_SINGLE_DH_USE
1808 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
1810 #ifdef SSL_OP_SINGLE_ECDH_USE
1811 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
1813 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
1814 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
1816 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
1817 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
1819 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
1820 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
1822 #ifdef SSL_OP_TLS_D5_BUG
1823 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
1825 #ifdef SSL_OP_TLS_ROLLBACK_BUG
1826 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
1829 static int exim_openssl_options_size =
1830 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
1834 tls_openssl_one_option_parse(uschar *name, long *value)
1837 int last = exim_openssl_options_size;
1838 while (last > first)
1840 int middle = (first + last)/2;
1841 int c = Ustrcmp(name, exim_openssl_options[middle].name);
1844 *value = exim_openssl_options[middle].value;
1858 /*************************************************
1859 * OpenSSL option parsing logic *
1860 *************************************************/
1862 /* OpenSSL has a number of compatibility options which an administrator might
1863 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
1864 we look like log_selector.
1867 option_spec the administrator-supplied string of options
1868 results ptr to long storage for the options bitmap
1869 Returns success or failure
1873 tls_openssl_options_parse(uschar *option_spec, long *results)
1878 BOOL adding, item_parsed;
1881 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
1882 * from default because it increases BEAST susceptibility. */
1883 #ifdef SSL_OP_NO_SSLv2
1884 result |= SSL_OP_NO_SSLv2;
1887 if (option_spec == NULL)
1893 for (s=option_spec; *s != '\0'; /**/)
1895 while (isspace(*s)) ++s;
1898 if (*s != '+' && *s != '-')
1900 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
1901 "+ or - expected but found \"%s\"\n", s);
1904 adding = *s++ == '+';
1905 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
1908 item_parsed = tls_openssl_one_option_parse(s, &item);
1911 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
1914 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
1915 adding ? "adding" : "removing", result, item, s);
1928 /* End of tls-openssl.c */