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
279 host connected host, if client; NULL if server
281 Returns: TRUE if OK (nothing to set up, or setup worked)
285 init_dh(uschar *dhparam, host_item *host)
292 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
295 if (dhexpanded == NULL) return TRUE;
297 if ((bio = BIO_new_file(CS dhexpanded, "r")) == NULL)
299 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
300 host, (uschar *)strerror(errno));
305 if ((dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)) == NULL)
307 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
313 if ((8*DH_size(dh)) > tls_dh_max_bits)
316 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
317 8*DH_size(dh), tls_dh_max_bits);
321 SSL_CTX_set_tmp_dh(ctx, dh);
323 debug_printf("Diffie-Hellman initialized from %s with %d-bit key\n",
324 dhexpanded, 8*DH_size(dh));
337 #ifdef EXPERIMENTAL_OCSP
338 /*************************************************
339 * Load OCSP information into state *
340 *************************************************/
342 /* Called to load the OCSP response from the given file into memory, once
343 caller has determined this is needed. Checks validity. Debugs a message
346 ASSUMES: single response, for single cert.
349 sctx the SSL_CTX* to update
350 cbinfo various parts of session state
351 expanded the filename putatively holding an OCSP response
356 ocsp_load_response(SSL_CTX *sctx,
357 tls_ext_ctx_cb *cbinfo,
358 const uschar *expanded)
362 OCSP_BASICRESP *basic_response;
363 OCSP_SINGLERESP *single_response;
364 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
366 unsigned long verify_flags;
367 int status, reason, i;
369 cbinfo->ocsp_file_expanded = string_copy(expanded);
370 if (cbinfo->ocsp_response)
372 OCSP_RESPONSE_free(cbinfo->ocsp_response);
373 cbinfo->ocsp_response = NULL;
376 bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb");
379 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
380 cbinfo->ocsp_file_expanded);
384 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
388 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
392 status = OCSP_response_status(resp);
393 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
395 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
396 OCSP_response_status_str(status), status);
400 basic_response = OCSP_response_get1_basic(resp);
404 debug_printf("OCSP response parse error: unable to extract basic response.\n");
408 store = SSL_CTX_get_cert_store(sctx);
409 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
411 /* May need to expose ability to adjust those flags?
412 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
413 OCSP_TRUSTOTHER OCSP_NOINTERN */
415 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
419 ERR_error_string(ERR_get_error(), ssl_errstring);
420 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
425 /* Here's the simplifying assumption: there's only one response, for the
426 one certificate we use, and nothing for anything else in a chain. If this
427 proves false, we need to extract a cert id from our issued cert
428 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
429 right cert in the stack and then calls OCSP_single_get0_status()).
431 I'm hoping to avoid reworking a bunch more of how we handle state here. */
432 single_response = OCSP_resp_get0(basic_response, 0);
433 if (!single_response)
436 debug_printf("Unable to get first response from OCSP basic response.\n");
440 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
441 /* how does this status differ from the one above? */
442 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
444 DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n",
445 OCSP_response_status_str(status), status);
449 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
451 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
455 cbinfo->ocsp_response = resp;
462 /*************************************************
463 * Expand key and cert file specs *
464 *************************************************/
466 /* Called once during tls_init and possibly againt during TLS setup, for a
467 new context, if Server Name Indication was used and tls_sni was seen in
468 the certificate string.
471 sctx the SSL_CTX* to update
472 cbinfo various parts of session state
474 Returns: OK/DEFER/FAIL
478 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
482 if (cbinfo->certificate == NULL)
485 if (Ustrstr(cbinfo->certificate, US"tls_sni"))
486 reexpand_tls_files_for_sni = TRUE;
488 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
491 if (expanded != NULL)
493 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
494 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
495 return tls_error(string_sprintf(
496 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
500 if (cbinfo->privatekey != NULL &&
501 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
504 /* If expansion was forced to fail, key_expanded will be NULL. If the result
505 of the expansion is an empty string, ignore it also, and assume the private
506 key is in the same file as the certificate. */
508 if (expanded != NULL && *expanded != 0)
510 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
511 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
512 return tls_error(string_sprintf(
513 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
516 #ifdef EXPERIMENTAL_OCSP
517 if (cbinfo->ocsp_file != NULL)
519 if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded))
522 if (expanded != NULL && *expanded != 0)
524 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
525 if (cbinfo->ocsp_file_expanded &&
526 (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0))
529 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
531 ocsp_load_response(sctx, cbinfo, expanded);
543 /*************************************************
544 * Callback to handle SNI *
545 *************************************************/
547 /* Called when acting as server during the TLS session setup if a Server Name
548 Indication extension was sent by the client.
550 API documentation is OpenSSL s_server.c implementation.
553 s SSL* of the current session
554 ad unknown (part of OpenSSL API) (unused)
555 arg Callback of "our" registered data
557 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
560 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
562 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
564 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
565 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
567 int old_pool = store_pool;
570 return SSL_TLSEXT_ERR_OK;
572 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
573 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
575 /* Make the extension value available for expansion */
576 store_pool = POOL_PERM;
577 tls_sni = string_copy(US servername);
578 store_pool = old_pool;
580 if (!reexpand_tls_files_for_sni)
581 return SSL_TLSEXT_ERR_OK;
583 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
584 not confident that memcpy wouldn't break some internal reference counting.
585 Especially since there's a references struct member, which would be off. */
587 ctx_sni = SSL_CTX_new(SSLv23_server_method());
590 ERR_error_string(ERR_get_error(), ssl_errstring);
591 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
592 return SSL_TLSEXT_ERR_NOACK;
595 /* Not sure how many of these are actually needed, since SSL object
596 already exists. Might even need this selfsame callback, for reneg? */
598 SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx));
599 SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx));
600 SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx));
601 SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx));
602 SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb);
603 SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo);
604 if (cbinfo->server_cipher_list)
605 SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list);
606 #ifdef EXPERIMENTAL_OCSP
607 if (cbinfo->ocsp_file)
609 SSL_CTX_set_tlsext_status_cb(ctx_sni, tls_stapling_cb);
610 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
614 rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE);
615 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
617 /* do this after setup_certs, because this can require the certs for verifying
619 rc = tls_expand_session_files(ctx_sni, cbinfo);
620 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
622 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
623 SSL_set_SSL_CTX(s, ctx_sni);
625 return SSL_TLSEXT_ERR_OK;
627 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
632 #ifdef EXPERIMENTAL_OCSP
633 /*************************************************
634 * Callback to handle OCSP Stapling *
635 *************************************************/
637 /* Called when acting as server during the TLS session setup if the client
638 requests OCSP information with a Certificate Status Request.
640 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
646 tls_stapling_cb(SSL *s, void *arg)
648 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
649 uschar *response_der;
650 int response_der_len;
652 DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n",
653 cbinfo->ocsp_response ? "have" : "lack");
654 if (!cbinfo->ocsp_response)
655 return SSL_TLSEXT_ERR_NOACK;
658 response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der);
659 if (response_der_len <= 0)
660 return SSL_TLSEXT_ERR_NOACK;
662 SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len);
663 return SSL_TLSEXT_ERR_OK;
666 #endif /* EXPERIMENTAL_OCSP */
671 /*************************************************
672 * Initialize for TLS *
673 *************************************************/
675 /* Called from both server and client code, to do preliminary initialization of
679 host connected host, if client; NULL if server
680 dhparam DH parameter file
681 certificate certificate file
682 privatekey private key
683 addr address if client; NULL if server (for some randomness)
685 Returns: OK/DEFER/FAIL
689 tls_init(host_item *host, uschar *dhparam, uschar *certificate,
691 #ifdef EXPERIMENTAL_OCSP
699 tls_ext_ctx_cb *cbinfo;
701 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
702 cbinfo->certificate = certificate;
703 cbinfo->privatekey = privatekey;
704 #ifdef EXPERIMENTAL_OCSP
705 cbinfo->ocsp_file = ocsp_file;
707 cbinfo->dhparam = dhparam;
710 SSL_load_error_strings(); /* basic set up */
711 OpenSSL_add_ssl_algorithms();
713 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
714 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
715 list of available digests. */
716 EVP_add_digest(EVP_sha256());
719 /* Create a context */
721 ctx = SSL_CTX_new((host == NULL)?
722 SSLv23_server_method() : SSLv23_client_method());
724 if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
726 /* It turns out that we need to seed the random number generator this early in
727 order to get the full complement of ciphers to work. It took me roughly a day
728 of work to discover this by experiment.
730 On systems that have /dev/urandom, SSL may automatically seed itself from
731 there. Otherwise, we have to make something up as best we can. Double check
737 gettimeofday(&r.tv, NULL);
740 RAND_seed((uschar *)(&r), sizeof(r));
741 RAND_seed((uschar *)big_buffer, big_buffer_size);
742 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
745 return tls_error(US"RAND_status", host,
746 US"unable to seed random number generator");
749 /* Set up the information callback, which outputs if debugging is at a suitable
752 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
754 /* Automatically re-try reads/writes after renegotiation. */
755 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
757 /* Apply administrator-supplied work-arounds.
758 Historically we applied just one requested option,
759 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
760 moved to an administrator-controlled list of options to specify and
761 grandfathered in the first one as the default value for "openssl_options".
763 No OpenSSL version number checks: the options we accept depend upon the
764 availability of the option value macros from OpenSSL. */
766 okay = tls_openssl_options_parse(openssl_options, &init_options);
768 return tls_error(US"openssl_options parsing failed", host, NULL);
772 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
773 if (!(SSL_CTX_set_options(ctx, init_options)))
774 return tls_error(string_sprintf(
775 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
778 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
780 /* Initialize with DH parameters if supplied */
782 if (!init_dh(dhparam, host)) return DEFER;
784 /* Set up certificate and key (and perhaps OCSP info) */
786 rc = tls_expand_session_files(ctx, cbinfo);
787 if (rc != OK) return rc;
789 /* If we need to handle SNI, do so */
790 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
793 #ifdef EXPERIMENTAL_OCSP
794 /* We check ocsp_file, not ocsp_response, because we care about if
795 the option exists, not what the current expansion might be, as SNI might
796 change the certificate and OCSP file in use between now and the time the
797 callback is invoked. */
798 if (cbinfo->ocsp_file)
800 SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb);
801 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
804 /* We always do this, so that $tls_sni is available even if not used in
806 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
807 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
811 /* Set up the RSA callback */
813 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
815 /* Finally, set the timeout, and we are done */
817 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
818 DEBUG(D_tls) debug_printf("Initialized TLS\n");
820 static_cbinfo = cbinfo;
828 /*************************************************
829 * Get name of cipher in use *
830 *************************************************/
832 /* The answer is left in a static buffer, and tls_cipher is set to point
835 Argument: pointer to an SSL structure for the connection
840 construct_cipher_name(SSL *ssl)
842 static uschar cipherbuf[256];
843 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
844 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
845 the accessor functions use const in the prototype. */
849 switch (ssl->session->ssl_version)
863 #ifdef TLS1_1_VERSION
869 #ifdef TLS1_2_VERSION
879 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
880 SSL_CIPHER_get_bits(c, &tls_bits);
882 string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
883 SSL_CIPHER_get_name(c), tls_bits);
884 tls_cipher = cipherbuf;
886 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
893 /*************************************************
894 * Set up for verifying certificates *
895 *************************************************/
897 /* Called by both client and server startup
900 sctx SSL_CTX* to initialise
901 certs certs file or NULL
903 host NULL in a server; the remote host in a client
904 optional TRUE if called from a server for a host in tls_try_verify_hosts;
905 otherwise passed as FALSE
907 Returns: OK/DEFER/FAIL
911 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional)
913 uschar *expcerts, *expcrl;
915 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
918 if (expcerts != NULL)
921 if (!SSL_CTX_set_default_verify_paths(sctx))
922 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
924 if (Ustat(expcerts, &statbuf) < 0)
926 log_write(0, LOG_MAIN|LOG_PANIC,
927 "failed to stat %s for certificates", expcerts);
933 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
934 { file = NULL; dir = expcerts; }
936 { file = expcerts; dir = NULL; }
938 /* If a certificate file is empty, the next function fails with an
939 unhelpful error message. If we skip it, we get the correct behaviour (no
940 certificates are recognized, but the error message is still misleading (it
941 says no certificate was supplied.) But this is better. */
943 if ((file == NULL || statbuf.st_size > 0) &&
944 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
945 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
949 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
953 /* Handle a certificate revocation list. */
955 #if OPENSSL_VERSION_NUMBER > 0x00907000L
957 /* This bit of code is now the version supplied by Lars Mainka. (I have
958 * merely reformatted it into the Exim code style.)
960 * "From here I changed the code to add support for multiple crl's
961 * in pem format in one file or to support hashed directory entries in
962 * pem format instead of a file. This method now uses the library function
963 * X509_STORE_load_locations to add the CRL location to the SSL context.
964 * OpenSSL will then handle the verify against CA certs and CRLs by
965 * itself in the verify callback." */
967 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
968 if (expcrl != NULL && *expcrl != 0)
970 struct stat statbufcrl;
971 if (Ustat(expcrl, &statbufcrl) < 0)
973 log_write(0, LOG_MAIN|LOG_PANIC,
974 "failed to stat %s for certificates revocation lists", expcrl);
979 /* is it a file or directory? */
981 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
982 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
986 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
992 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
994 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
995 return tls_error(US"X509_STORE_load_locations", host, NULL);
997 /* setting the flags to check against the complete crl chain */
999 X509_STORE_set_flags(cvstore,
1000 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1004 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1006 /* If verification is optional, don't fail if no certificate */
1008 SSL_CTX_set_verify(sctx,
1009 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1018 /*************************************************
1019 * Start a TLS session in a server *
1020 *************************************************/
1022 /* This is called when Exim is running as a server, after having received
1023 the STARTTLS command. It must respond to that command, and then negotiate
1027 require_ciphers allowed ciphers
1029 Returns: OK on success
1030 DEFER for errors before the start of the negotiation
1031 FAIL for errors during the negotation; the server can't
1036 tls_server_start(const uschar *require_ciphers)
1040 tls_ext_ctx_cb *cbinfo;
1042 /* Check for previous activation */
1044 if (tls_active >= 0)
1046 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1047 smtp_printf("554 Already in TLS\r\n");
1051 /* Initialize the SSL library. If it fails, it will already have logged
1054 rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey,
1055 #ifdef EXPERIMENTAL_OCSP
1059 if (rc != OK) return rc;
1060 cbinfo = static_cbinfo;
1062 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1065 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1066 were historically separated by underscores. So that I can use either form in my
1067 tests, and also for general convenience, we turn underscores into hyphens here.
1070 if (expciphers != NULL)
1072 uschar *s = expciphers;
1073 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1074 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1075 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1076 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1077 cbinfo->server_cipher_list = expciphers;
1080 /* If this is a host for which certificate verification is mandatory or
1081 optional, set up appropriately. */
1083 tls_certificate_verified = FALSE;
1084 verify_callback_called = FALSE;
1086 if (verify_check_host(&tls_verify_hosts) == OK)
1088 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE);
1089 if (rc != OK) return rc;
1090 verify_optional = FALSE;
1092 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1094 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE);
1095 if (rc != OK) return rc;
1096 verify_optional = TRUE;
1099 /* Prepare for new connection */
1101 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1103 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1105 * With the SSL_clear(), we get strange interoperability bugs with
1106 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1107 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1109 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1110 * session shutdown. In this case, we have a brand new object and there's no
1111 * obvious reason to immediately clear it. I'm guessing that this was
1112 * originally added because of incomplete initialisation which the clear fixed,
1113 * in some historic release.
1116 /* Set context and tell client to go ahead, except in the case of TLS startup
1117 on connection, where outputting anything now upsets the clients and tends to
1118 make them disconnect. We need to have an explicit fflush() here, to force out
1119 the response. Other smtp_printf() calls do not need it, because in non-TLS
1120 mode, the fflush() happens when smtp_getc() is called. */
1122 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1123 if (!tls_on_connect)
1125 smtp_printf("220 TLS go ahead\r\n");
1129 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1130 that the OpenSSL library doesn't. */
1132 SSL_set_wfd(ssl, fileno(smtp_out));
1133 SSL_set_rfd(ssl, fileno(smtp_in));
1134 SSL_set_accept_state(ssl);
1136 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1138 sigalrm_seen = FALSE;
1139 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1140 rc = SSL_accept(ssl);
1145 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1146 if (ERR_get_error() == 0)
1147 log_write(0, LOG_MAIN,
1148 "TLS client disconnected cleanly (rejected our certificate?)");
1152 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1154 /* TLS has been set up. Adjust the input functions to read via TLS,
1155 and initialize things. */
1157 construct_cipher_name(ssl);
1162 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL)
1163 debug_printf("Shared ciphers: %s\n", buf);
1167 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1168 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1169 ssl_xfer_eof = ssl_xfer_error = 0;
1171 receive_getc = tls_getc;
1172 receive_ungetc = tls_ungetc;
1173 receive_feof = tls_feof;
1174 receive_ferror = tls_ferror;
1175 receive_smtp_buffered = tls_smtp_buffered;
1177 tls_active = fileno(smtp_out);
1185 /*************************************************
1186 * Start a TLS session in a client *
1187 *************************************************/
1189 /* Called from the smtp transport after STARTTLS has been accepted.
1192 fd the fd of the connection
1193 host connected host (for messages)
1194 addr the first address
1195 dhparam DH parameter file
1196 certificate certificate file
1197 privatekey private key file
1198 sni TLS SNI to send to remote host
1199 verify_certs file for certificate verify
1200 crl file containing CRL
1201 require_ciphers list of allowed ciphers
1202 timeout startup timeout
1204 Returns: OK on success
1205 FAIL otherwise - note that tls_error() will not give DEFER
1206 because this is not a server
1210 tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
1211 uschar *certificate, uschar *privatekey, uschar *sni,
1212 uschar *verify_certs, uschar *crl,
1213 uschar *require_ciphers, int timeout)
1215 static uschar txt[256];
1220 rc = tls_init(host, dhparam, certificate, privatekey,
1221 #ifdef EXPERIMENTAL_OCSP
1225 if (rc != OK) return rc;
1227 tls_certificate_verified = FALSE;
1228 verify_callback_called = FALSE;
1230 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1233 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1234 are separated by underscores. So that I can use either form in my tests, and
1235 also for general convenience, we turn underscores into hyphens here. */
1237 if (expciphers != NULL)
1239 uschar *s = expciphers;
1240 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1241 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1242 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1243 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1246 rc = setup_certs(ctx, verify_certs, crl, host, FALSE);
1247 if (rc != OK) return rc;
1249 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1250 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1251 SSL_set_fd(ssl, fd);
1252 SSL_set_connect_state(ssl);
1256 if (!expand_check(sni, US"tls_sni", &tls_sni))
1258 if (!Ustrlen(tls_sni))
1262 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1263 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni);
1264 SSL_set_tlsext_host_name(ssl, tls_sni);
1267 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1273 /* There doesn't seem to be a built-in timeout on connection. */
1275 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1276 sigalrm_seen = FALSE;
1278 rc = SSL_connect(ssl);
1282 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1284 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1286 /* Beware anonymous ciphers which lead to server_cert being NULL */
1287 server_cert = SSL_get_peer_certificate (ssl);
1290 tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1291 CS txt, sizeof(txt));
1297 construct_cipher_name(ssl); /* Sets tls_cipher */
1307 /*************************************************
1308 * TLS version of getc *
1309 *************************************************/
1311 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1312 it refills the buffer via the SSL reading function.
1315 Returns: the next character or EOF
1321 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1326 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1327 ssl_xfer_buffer, ssl_xfer_buffer_size);
1329 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1330 inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1331 error = SSL_get_error(ssl, inbytes);
1334 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1335 closed down, not that the socket itself has been closed down. Revert to
1336 non-SSL handling. */
1338 if (error == SSL_ERROR_ZERO_RETURN)
1340 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1342 receive_getc = smtp_getc;
1343 receive_ungetc = smtp_ungetc;
1344 receive_feof = smtp_feof;
1345 receive_ferror = smtp_ferror;
1346 receive_smtp_buffered = smtp_buffered;
1359 /* Handle genuine errors */
1361 else if (error == SSL_ERROR_SSL)
1363 ERR_error_string(ERR_get_error(), ssl_errstring);
1364 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
1369 else if (error != SSL_ERROR_NONE)
1371 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1376 #ifndef DISABLE_DKIM
1377 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1379 ssl_xfer_buffer_hwm = inbytes;
1380 ssl_xfer_buffer_lwm = 0;
1383 /* Something in the buffer; return next uschar */
1385 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1390 /*************************************************
1391 * Read bytes from TLS channel *
1392 *************************************************/
1399 Returns: the number of bytes read
1400 -1 after a failed read
1404 tls_read(uschar *buff, size_t len)
1409 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1410 buff, (unsigned int)len);
1412 inbytes = SSL_read(ssl, CS buff, len);
1413 error = SSL_get_error(ssl, inbytes);
1415 if (error == SSL_ERROR_ZERO_RETURN)
1417 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1420 else if (error != SSL_ERROR_NONE)
1432 /*************************************************
1433 * Write bytes down TLS channel *
1434 *************************************************/
1441 Returns: the number of bytes after a successful write,
1442 -1 after a failed write
1446 tls_write(const uschar *buff, size_t len)
1452 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
1455 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
1456 outbytes = SSL_write(ssl, CS buff, left);
1457 error = SSL_get_error(ssl, outbytes);
1458 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1462 ERR_error_string(ERR_get_error(), ssl_errstring);
1463 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1466 case SSL_ERROR_NONE:
1471 case SSL_ERROR_ZERO_RETURN:
1472 log_write(0, LOG_MAIN, "SSL channel closed on write");
1476 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1485 /*************************************************
1486 * Close down a TLS session *
1487 *************************************************/
1489 /* This is also called from within a delivery subprocess forked from the
1490 daemon, to shut down the TLS library, without actually doing a shutdown (which
1491 would tamper with the SSL session in the parent process).
1493 Arguments: TRUE if SSL_shutdown is to be called
1498 tls_close(BOOL shutdown)
1500 if (tls_active < 0) return; /* TLS was not active */
1504 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
1517 /*************************************************
1518 * Let tls_require_ciphers be checked at startup *
1519 *************************************************/
1521 /* The tls_require_ciphers option, if set, must be something which the
1524 Returns: NULL on success, or error message
1528 tls_validate_require_cipher(void)
1531 uschar *s, *expciphers, *err;
1533 /* this duplicates from tls_init(), we need a better "init just global
1534 state, for no specific purpose" singleton function of our own */
1536 SSL_load_error_strings();
1537 OpenSSL_add_ssl_algorithms();
1538 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1539 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1540 list of available digests. */
1541 EVP_add_digest(EVP_sha256());
1544 if (!(tls_require_ciphers && *tls_require_ciphers))
1547 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1548 return US"failed to expand tls_require_ciphers";
1550 if (!(expciphers && *expciphers))
1553 /* normalisation ripped from above */
1555 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1559 ctx = SSL_CTX_new(SSLv23_server_method());
1562 ERR_error_string(ERR_get_error(), ssl_errstring);
1563 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1567 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1569 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1571 ERR_error_string(ERR_get_error(), ssl_errstring);
1572 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1583 /*************************************************
1584 * Report the library versions. *
1585 *************************************************/
1587 /* There have historically been some issues with binary compatibility in
1588 OpenSSL libraries; if Exim (like many other applications) is built against
1589 one version of OpenSSL but the run-time linker picks up another version,
1590 it can result in serious failures, including crashing with a SIGSEGV. So
1591 report the version found by the compiler and the run-time version.
1593 Arguments: a FILE* to print the results to
1598 tls_version_report(FILE *f)
1600 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1602 OPENSSL_VERSION_TEXT,
1603 SSLeay_version(SSLEAY_VERSION));
1609 /*************************************************
1610 * Random number generation *
1611 *************************************************/
1613 /* Pseudo-random number generation. The result is not expected to be
1614 cryptographically strong but not so weak that someone will shoot themselves
1615 in the foot using it as a nonce in input in some email header scheme or
1616 whatever weirdness they'll twist this into. The result should handle fork()
1617 and avoid repeating sequences. OpenSSL handles that for us.
1621 Returns a random number in range [0, max-1]
1625 vaguely_random_number(int max)
1630 uschar smallbuf[sizeof(r)];
1635 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1639 gettimeofday(&r.tv, NULL);
1642 RAND_seed((uschar *)(&r), sizeof(r));
1644 /* We're after pseudo-random, not random; if we still don't have enough data
1645 in the internal PRNG then our options are limited. We could sleep and hope
1646 for entropy to come along (prayer technique) but if the system is so depleted
1647 in the first place then something is likely to just keep taking it. Instead,
1648 we'll just take whatever little bit of pseudo-random we can still manage to
1651 needed_len = sizeof(r);
1652 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1653 asked for a number less than 10. */
1654 for (r = max, i = 0; r; ++i)
1660 /* We do not care if crypto-strong */
1661 i = RAND_pseudo_bytes(smallbuf, needed_len);
1665 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
1666 return vaguely_random_number_fallback(max);
1670 for (p = smallbuf; needed_len; --needed_len, ++p)
1676 /* We don't particularly care about weighted results; if someone wants
1677 smooth distribution and cares enough then they should submit a patch then. */
1684 /*************************************************
1685 * OpenSSL option parse *
1686 *************************************************/
1688 /* Parse one option for tls_openssl_options_parse below
1691 name one option name
1692 value place to store a value for it
1693 Returns success or failure in parsing
1696 struct exim_openssl_option {
1700 /* We could use a macro to expand, but we need the ifdef and not all the
1701 options document which version they were introduced in. Policylet: include
1702 all options unless explicitly for DTLS, let the administrator choose which
1705 This list is current as of:
1707 static struct exim_openssl_option exim_openssl_options[] = {
1708 /* KEEP SORTED ALPHABETICALLY! */
1710 { US"all", SSL_OP_ALL },
1712 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
1713 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
1715 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
1716 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
1718 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1719 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
1721 #ifdef SSL_OP_EPHEMERAL_RSA
1722 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
1724 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
1725 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
1727 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
1728 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
1730 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
1731 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
1733 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
1734 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
1736 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
1737 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
1739 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
1740 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
1742 #ifdef SSL_OP_NO_COMPRESSION
1743 { US"no_compression", SSL_OP_NO_COMPRESSION },
1745 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
1746 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
1748 #ifdef SSL_OP_NO_SSLv2
1749 { US"no_sslv2", SSL_OP_NO_SSLv2 },
1751 #ifdef SSL_OP_NO_SSLv3
1752 { US"no_sslv3", SSL_OP_NO_SSLv3 },
1754 #ifdef SSL_OP_NO_TICKET
1755 { US"no_ticket", SSL_OP_NO_TICKET },
1757 #ifdef SSL_OP_NO_TLSv1
1758 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
1760 #ifdef SSL_OP_NO_TLSv1_1
1761 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
1762 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
1763 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
1765 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
1768 #ifdef SSL_OP_NO_TLSv1_2
1769 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
1771 #ifdef SSL_OP_SINGLE_DH_USE
1772 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
1774 #ifdef SSL_OP_SINGLE_ECDH_USE
1775 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
1777 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
1778 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
1780 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
1781 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
1783 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
1784 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
1786 #ifdef SSL_OP_TLS_D5_BUG
1787 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
1789 #ifdef SSL_OP_TLS_ROLLBACK_BUG
1790 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
1793 static int exim_openssl_options_size =
1794 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
1798 tls_openssl_one_option_parse(uschar *name, long *value)
1801 int last = exim_openssl_options_size;
1802 while (last > first)
1804 int middle = (first + last)/2;
1805 int c = Ustrcmp(name, exim_openssl_options[middle].name);
1808 *value = exim_openssl_options[middle].value;
1822 /*************************************************
1823 * OpenSSL option parsing logic *
1824 *************************************************/
1826 /* OpenSSL has a number of compatibility options which an administrator might
1827 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
1828 we look like log_selector.
1831 option_spec the administrator-supplied string of options
1832 results ptr to long storage for the options bitmap
1833 Returns success or failure
1837 tls_openssl_options_parse(uschar *option_spec, long *results)
1842 BOOL adding, item_parsed;
1845 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
1846 * from default because it increases BEAST susceptibility. */
1848 if (option_spec == NULL)
1854 for (s=option_spec; *s != '\0'; /**/)
1856 while (isspace(*s)) ++s;
1859 if (*s != '+' && *s != '-')
1861 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
1862 "+ or - expected but found \"%s\"\n", s);
1865 adding = *s++ == '+';
1866 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
1869 item_parsed = tls_openssl_one_option_parse(s, &item);
1872 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
1875 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
1876 adding ? "adding" : "removing", result, item, s);
1889 /* End of tls-openssl.c */