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");
478 if (environ) for (p = USS environ; *p != NULL; p++)
481 cbinfo->ocsp_response = resp;
488 /*************************************************
489 * Expand key and cert file specs *
490 *************************************************/
492 /* Called once during tls_init and possibly againt during TLS setup, for a
493 new context, if Server Name Indication was used and tls_sni was seen in
494 the certificate string.
497 sctx the SSL_CTX* to update
498 cbinfo various parts of session state
500 Returns: OK/DEFER/FAIL
504 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
508 if (cbinfo->certificate == NULL)
511 if (Ustrstr(cbinfo->certificate, US"tls_sni"))
512 reexpand_tls_files_for_sni = TRUE;
514 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
517 if (expanded != NULL)
519 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
520 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
521 return tls_error(string_sprintf(
522 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
526 if (cbinfo->privatekey != NULL &&
527 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
530 /* If expansion was forced to fail, key_expanded will be NULL. If the result
531 of the expansion is an empty string, ignore it also, and assume the private
532 key is in the same file as the certificate. */
534 if (expanded != NULL && *expanded != 0)
536 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
537 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
538 return tls_error(string_sprintf(
539 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
542 #ifdef EXPERIMENTAL_OCSP
543 if (cbinfo->ocsp_file != NULL)
545 if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded))
548 if (expanded != NULL && *expanded != 0)
550 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
551 if (cbinfo->ocsp_file_expanded &&
552 (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0))
555 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
557 ocsp_load_response(sctx, cbinfo, expanded);
569 /*************************************************
570 * Callback to handle SNI *
571 *************************************************/
573 /* Called when acting as server during the TLS session setup if a Server Name
574 Indication extension was sent by the client.
576 API documentation is OpenSSL s_server.c implementation.
579 s SSL* of the current session
580 ad unknown (part of OpenSSL API) (unused)
581 arg Callback of "our" registered data
583 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
586 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
588 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
590 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
591 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
593 int old_pool = store_pool;
596 return SSL_TLSEXT_ERR_OK;
598 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
599 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
601 /* Make the extension value available for expansion */
602 store_pool = POOL_PERM;
603 tls_sni = string_copy(US servername);
604 store_pool = old_pool;
606 if (!reexpand_tls_files_for_sni)
607 return SSL_TLSEXT_ERR_OK;
609 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
610 not confident that memcpy wouldn't break some internal reference counting.
611 Especially since there's a references struct member, which would be off. */
613 ctx_sni = SSL_CTX_new(SSLv23_server_method());
616 ERR_error_string(ERR_get_error(), ssl_errstring);
617 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
618 return SSL_TLSEXT_ERR_NOACK;
621 /* Not sure how many of these are actually needed, since SSL object
622 already exists. Might even need this selfsame callback, for reneg? */
624 SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx));
625 SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx));
626 SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx));
627 SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx));
628 SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb);
629 SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo);
630 if (cbinfo->server_cipher_list)
631 SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list);
632 #ifdef EXPERIMENTAL_OCSP
633 if (cbinfo->ocsp_file)
635 SSL_CTX_set_tlsext_status_cb(ctx_sni, tls_stapling_cb);
636 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
640 rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE);
641 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
643 /* do this after setup_certs, because this can require the certs for verifying
645 rc = tls_expand_session_files(ctx_sni, cbinfo);
646 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
648 rc = init_dh(ctx_sni, cbinfo->dhparam, NULL);
649 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
651 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
652 SSL_set_SSL_CTX(s, ctx_sni);
654 return SSL_TLSEXT_ERR_OK;
656 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
661 #ifdef EXPERIMENTAL_OCSP
662 /*************************************************
663 * Callback to handle OCSP Stapling *
664 *************************************************/
666 /* Called when acting as server during the TLS session setup if the client
667 requests OCSP information with a Certificate Status Request.
669 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
675 tls_stapling_cb(SSL *s, void *arg)
677 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
678 uschar *response_der;
679 int response_der_len;
681 DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n",
682 cbinfo->ocsp_response ? "have" : "lack");
683 if (!cbinfo->ocsp_response)
684 return SSL_TLSEXT_ERR_NOACK;
687 response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der);
688 if (response_der_len <= 0)
689 return SSL_TLSEXT_ERR_NOACK;
691 SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len);
692 return SSL_TLSEXT_ERR_OK;
695 #endif /* EXPERIMENTAL_OCSP */
700 /*************************************************
701 * Initialize for TLS *
702 *************************************************/
704 /* Called from both server and client code, to do preliminary initialization of
708 host connected host, if client; NULL if server
709 dhparam DH parameter file
710 certificate certificate file
711 privatekey private key
712 addr address if client; NULL if server (for some randomness)
714 Returns: OK/DEFER/FAIL
718 tls_init(host_item *host, uschar *dhparam, uschar *certificate,
720 #ifdef EXPERIMENTAL_OCSP
728 tls_ext_ctx_cb *cbinfo;
730 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
731 cbinfo->certificate = certificate;
732 cbinfo->privatekey = privatekey;
733 #ifdef EXPERIMENTAL_OCSP
734 cbinfo->ocsp_file = ocsp_file;
736 cbinfo->dhparam = dhparam;
739 SSL_load_error_strings(); /* basic set up */
740 OpenSSL_add_ssl_algorithms();
742 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
743 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
744 list of available digests. */
745 EVP_add_digest(EVP_sha256());
749 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
750 negotiation in the different methods; as far as I can tell, the only
751 *_{server,client}_method which allows negotiation is SSLv23, which exists even
752 when OpenSSL is built without SSLv2 support.
753 By disabling with openssl_options, we can let admins re-enable with the
756 ctx = SSL_CTX_new((host == NULL)?
757 SSLv23_server_method() : SSLv23_client_method());
759 if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
761 /* It turns out that we need to seed the random number generator this early in
762 order to get the full complement of ciphers to work. It took me roughly a day
763 of work to discover this by experiment.
765 On systems that have /dev/urandom, SSL may automatically seed itself from
766 there. Otherwise, we have to make something up as best we can. Double check
772 gettimeofday(&r.tv, NULL);
775 RAND_seed((uschar *)(&r), sizeof(r));
776 RAND_seed((uschar *)big_buffer, big_buffer_size);
777 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
780 return tls_error(US"RAND_status", host,
781 US"unable to seed random number generator");
784 /* Set up the information callback, which outputs if debugging is at a suitable
787 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
789 /* Automatically re-try reads/writes after renegotiation. */
790 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
792 /* Apply administrator-supplied work-arounds.
793 Historically we applied just one requested option,
794 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
795 moved to an administrator-controlled list of options to specify and
796 grandfathered in the first one as the default value for "openssl_options".
798 No OpenSSL version number checks: the options we accept depend upon the
799 availability of the option value macros from OpenSSL. */
801 okay = tls_openssl_options_parse(openssl_options, &init_options);
803 return tls_error(US"openssl_options parsing failed", host, NULL);
807 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
808 if (!(SSL_CTX_set_options(ctx, init_options)))
809 return tls_error(string_sprintf(
810 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
813 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
815 /* Initialize with DH parameters if supplied */
817 if (!init_dh(ctx, dhparam, host)) return DEFER;
819 /* Set up certificate and key (and perhaps OCSP info) */
821 rc = tls_expand_session_files(ctx, cbinfo);
822 if (rc != OK) return rc;
824 /* If we need to handle SNI, do so */
825 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
828 #ifdef EXPERIMENTAL_OCSP
829 /* We check ocsp_file, not ocsp_response, because we care about if
830 the option exists, not what the current expansion might be, as SNI might
831 change the certificate and OCSP file in use between now and the time the
832 callback is invoked. */
833 if (cbinfo->ocsp_file)
835 SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb);
836 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
839 /* We always do this, so that $tls_sni is available even if not used in
841 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
842 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
846 /* Set up the RSA callback */
848 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
850 /* Finally, set the timeout, and we are done */
852 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
853 DEBUG(D_tls) debug_printf("Initialized TLS\n");
855 static_cbinfo = cbinfo;
863 /*************************************************
864 * Get name of cipher in use *
865 *************************************************/
867 /* The answer is left in a static buffer, and tls_cipher is set to point
870 Argument: pointer to an SSL structure for the connection
875 construct_cipher_name(SSL *ssl)
877 static uschar cipherbuf[256];
878 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
879 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
880 the accessor functions use const in the prototype. */
884 switch (ssl->session->ssl_version)
898 #ifdef TLS1_1_VERSION
904 #ifdef TLS1_2_VERSION
914 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
915 SSL_CIPHER_get_bits(c, &tls_bits);
917 string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
918 SSL_CIPHER_get_name(c), tls_bits);
919 tls_cipher = cipherbuf;
921 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
928 /*************************************************
929 * Set up for verifying certificates *
930 *************************************************/
932 /* Called by both client and server startup
935 sctx SSL_CTX* to initialise
936 certs certs file or NULL
938 host NULL in a server; the remote host in a client
939 optional TRUE if called from a server for a host in tls_try_verify_hosts;
940 otherwise passed as FALSE
942 Returns: OK/DEFER/FAIL
946 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional)
948 uschar *expcerts, *expcrl;
950 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
953 if (expcerts != NULL)
956 if (!SSL_CTX_set_default_verify_paths(sctx))
957 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
959 if (Ustat(expcerts, &statbuf) < 0)
961 log_write(0, LOG_MAIN|LOG_PANIC,
962 "failed to stat %s for certificates", expcerts);
968 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
969 { file = NULL; dir = expcerts; }
971 { file = expcerts; dir = NULL; }
973 /* If a certificate file is empty, the next function fails with an
974 unhelpful error message. If we skip it, we get the correct behaviour (no
975 certificates are recognized, but the error message is still misleading (it
976 says no certificate was supplied.) But this is better. */
978 if ((file == NULL || statbuf.st_size > 0) &&
979 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
980 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
984 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
988 /* Handle a certificate revocation list. */
990 #if OPENSSL_VERSION_NUMBER > 0x00907000L
992 /* This bit of code is now the version supplied by Lars Mainka. (I have
993 * merely reformatted it into the Exim code style.)
995 * "From here I changed the code to add support for multiple crl's
996 * in pem format in one file or to support hashed directory entries in
997 * pem format instead of a file. This method now uses the library function
998 * X509_STORE_load_locations to add the CRL location to the SSL context.
999 * OpenSSL will then handle the verify against CA certs and CRLs by
1000 * itself in the verify callback." */
1002 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1003 if (expcrl != NULL && *expcrl != 0)
1005 struct stat statbufcrl;
1006 if (Ustat(expcrl, &statbufcrl) < 0)
1008 log_write(0, LOG_MAIN|LOG_PANIC,
1009 "failed to stat %s for certificates revocation lists", expcrl);
1014 /* is it a file or directory? */
1016 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1017 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1021 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1027 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1029 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1030 return tls_error(US"X509_STORE_load_locations", host, NULL);
1032 /* setting the flags to check against the complete crl chain */
1034 X509_STORE_set_flags(cvstore,
1035 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1039 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1041 /* If verification is optional, don't fail if no certificate */
1043 SSL_CTX_set_verify(sctx,
1044 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1053 /*************************************************
1054 * Start a TLS session in a server *
1055 *************************************************/
1057 /* This is called when Exim is running as a server, after having received
1058 the STARTTLS command. It must respond to that command, and then negotiate
1062 require_ciphers allowed ciphers
1064 Returns: OK on success
1065 DEFER for errors before the start of the negotiation
1066 FAIL for errors during the negotation; the server can't
1071 tls_server_start(const uschar *require_ciphers)
1075 tls_ext_ctx_cb *cbinfo;
1077 /* Check for previous activation */
1079 if (tls_active >= 0)
1081 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1082 smtp_printf("554 Already in TLS\r\n");
1086 /* Initialize the SSL library. If it fails, it will already have logged
1089 rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey,
1090 #ifdef EXPERIMENTAL_OCSP
1094 if (rc != OK) return rc;
1095 cbinfo = static_cbinfo;
1097 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1100 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1101 were historically separated by underscores. So that I can use either form in my
1102 tests, and also for general convenience, we turn underscores into hyphens here.
1105 if (expciphers != NULL)
1107 uschar *s = expciphers;
1108 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1109 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1110 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1111 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1112 cbinfo->server_cipher_list = expciphers;
1115 /* If this is a host for which certificate verification is mandatory or
1116 optional, set up appropriately. */
1118 tls_certificate_verified = FALSE;
1119 verify_callback_called = FALSE;
1121 if (verify_check_host(&tls_verify_hosts) == OK)
1123 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE);
1124 if (rc != OK) return rc;
1125 verify_optional = FALSE;
1127 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1129 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE);
1130 if (rc != OK) return rc;
1131 verify_optional = TRUE;
1134 /* Prepare for new connection */
1136 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1138 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1140 * With the SSL_clear(), we get strange interoperability bugs with
1141 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1142 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1144 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1145 * session shutdown. In this case, we have a brand new object and there's no
1146 * obvious reason to immediately clear it. I'm guessing that this was
1147 * originally added because of incomplete initialisation which the clear fixed,
1148 * in some historic release.
1151 /* Set context and tell client to go ahead, except in the case of TLS startup
1152 on connection, where outputting anything now upsets the clients and tends to
1153 make them disconnect. We need to have an explicit fflush() here, to force out
1154 the response. Other smtp_printf() calls do not need it, because in non-TLS
1155 mode, the fflush() happens when smtp_getc() is called. */
1157 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1158 if (!tls_on_connect)
1160 smtp_printf("220 TLS go ahead\r\n");
1164 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1165 that the OpenSSL library doesn't. */
1167 SSL_set_wfd(ssl, fileno(smtp_out));
1168 SSL_set_rfd(ssl, fileno(smtp_in));
1169 SSL_set_accept_state(ssl);
1171 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1173 sigalrm_seen = FALSE;
1174 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1175 rc = SSL_accept(ssl);
1180 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1181 if (ERR_get_error() == 0)
1182 log_write(0, LOG_MAIN,
1183 "TLS client disconnected cleanly (rejected our certificate?)");
1187 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1189 /* TLS has been set up. Adjust the input functions to read via TLS,
1190 and initialize things. */
1192 construct_cipher_name(ssl);
1197 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL)
1198 debug_printf("Shared ciphers: %s\n", buf);
1202 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1203 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1204 ssl_xfer_eof = ssl_xfer_error = 0;
1206 receive_getc = tls_getc;
1207 receive_ungetc = tls_ungetc;
1208 receive_feof = tls_feof;
1209 receive_ferror = tls_ferror;
1210 receive_smtp_buffered = tls_smtp_buffered;
1212 tls_active = fileno(smtp_out);
1220 /*************************************************
1221 * Start a TLS session in a client *
1222 *************************************************/
1224 /* Called from the smtp transport after STARTTLS has been accepted.
1227 fd the fd of the connection
1228 host connected host (for messages)
1229 addr the first address
1230 dhparam DH parameter file
1231 certificate certificate file
1232 privatekey private key file
1233 sni TLS SNI to send to remote host
1234 verify_certs file for certificate verify
1235 crl file containing CRL
1236 require_ciphers list of allowed ciphers
1237 timeout startup timeout
1239 Returns: OK on success
1240 FAIL otherwise - note that tls_error() will not give DEFER
1241 because this is not a server
1245 tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
1246 uschar *certificate, uschar *privatekey, uschar *sni,
1247 uschar *verify_certs, uschar *crl,
1248 uschar *require_ciphers, int timeout)
1250 static uschar txt[256];
1255 rc = tls_init(host, dhparam, certificate, privatekey,
1256 #ifdef EXPERIMENTAL_OCSP
1260 if (rc != OK) return rc;
1262 tls_certificate_verified = FALSE;
1263 verify_callback_called = FALSE;
1265 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1268 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1269 are separated by underscores. So that I can use either form in my tests, and
1270 also for general convenience, we turn underscores into hyphens here. */
1272 if (expciphers != NULL)
1274 uschar *s = expciphers;
1275 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1276 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1277 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1278 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1281 rc = setup_certs(ctx, verify_certs, crl, host, FALSE);
1282 if (rc != OK) return rc;
1284 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1285 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1286 SSL_set_fd(ssl, fd);
1287 SSL_set_connect_state(ssl);
1291 if (!expand_check(sni, US"tls_sni", &tls_sni))
1293 if (!Ustrlen(tls_sni))
1297 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1298 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni);
1299 SSL_set_tlsext_host_name(ssl, tls_sni);
1302 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1308 /* There doesn't seem to be a built-in timeout on connection. */
1310 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1311 sigalrm_seen = FALSE;
1313 rc = SSL_connect(ssl);
1317 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1319 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1321 /* Beware anonymous ciphers which lead to server_cert being NULL */
1322 server_cert = SSL_get_peer_certificate (ssl);
1325 tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1326 CS txt, sizeof(txt));
1332 construct_cipher_name(ssl); /* Sets tls_cipher */
1342 /*************************************************
1343 * TLS version of getc *
1344 *************************************************/
1346 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1347 it refills the buffer via the SSL reading function.
1350 Returns: the next character or EOF
1356 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1361 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1362 ssl_xfer_buffer, ssl_xfer_buffer_size);
1364 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1365 inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1366 error = SSL_get_error(ssl, inbytes);
1369 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1370 closed down, not that the socket itself has been closed down. Revert to
1371 non-SSL handling. */
1373 if (error == SSL_ERROR_ZERO_RETURN)
1375 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1377 receive_getc = smtp_getc;
1378 receive_ungetc = smtp_ungetc;
1379 receive_feof = smtp_feof;
1380 receive_ferror = smtp_ferror;
1381 receive_smtp_buffered = smtp_buffered;
1394 /* Handle genuine errors */
1396 else if (error == SSL_ERROR_SSL)
1398 ERR_error_string(ERR_get_error(), ssl_errstring);
1399 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
1404 else if (error != SSL_ERROR_NONE)
1406 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1411 #ifndef DISABLE_DKIM
1412 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1414 ssl_xfer_buffer_hwm = inbytes;
1415 ssl_xfer_buffer_lwm = 0;
1418 /* Something in the buffer; return next uschar */
1420 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1425 /*************************************************
1426 * Read bytes from TLS channel *
1427 *************************************************/
1434 Returns: the number of bytes read
1435 -1 after a failed read
1439 tls_read(uschar *buff, size_t len)
1444 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1445 buff, (unsigned int)len);
1447 inbytes = SSL_read(ssl, CS buff, len);
1448 error = SSL_get_error(ssl, inbytes);
1450 if (error == SSL_ERROR_ZERO_RETURN)
1452 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1455 else if (error != SSL_ERROR_NONE)
1467 /*************************************************
1468 * Write bytes down TLS channel *
1469 *************************************************/
1476 Returns: the number of bytes after a successful write,
1477 -1 after a failed write
1481 tls_write(const uschar *buff, size_t len)
1487 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
1490 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
1491 outbytes = SSL_write(ssl, CS buff, left);
1492 error = SSL_get_error(ssl, outbytes);
1493 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1497 ERR_error_string(ERR_get_error(), ssl_errstring);
1498 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1501 case SSL_ERROR_NONE:
1506 case SSL_ERROR_ZERO_RETURN:
1507 log_write(0, LOG_MAIN, "SSL channel closed on write");
1511 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1520 /*************************************************
1521 * Close down a TLS session *
1522 *************************************************/
1524 /* This is also called from within a delivery subprocess forked from the
1525 daemon, to shut down the TLS library, without actually doing a shutdown (which
1526 would tamper with the SSL session in the parent process).
1528 Arguments: TRUE if SSL_shutdown is to be called
1533 tls_close(BOOL shutdown)
1535 if (tls_active < 0) return; /* TLS was not active */
1539 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
1552 /*************************************************
1553 * Let tls_require_ciphers be checked at startup *
1554 *************************************************/
1556 /* The tls_require_ciphers option, if set, must be something which the
1559 Returns: NULL on success, or error message
1563 tls_validate_require_cipher(void)
1566 uschar *s, *expciphers, *err;
1568 /* this duplicates from tls_init(), we need a better "init just global
1569 state, for no specific purpose" singleton function of our own */
1571 SSL_load_error_strings();
1572 OpenSSL_add_ssl_algorithms();
1573 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1574 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1575 list of available digests. */
1576 EVP_add_digest(EVP_sha256());
1579 if (!(tls_require_ciphers && *tls_require_ciphers))
1582 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1583 return US"failed to expand tls_require_ciphers";
1585 if (!(expciphers && *expciphers))
1588 /* normalisation ripped from above */
1590 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1594 ctx = SSL_CTX_new(SSLv23_server_method());
1597 ERR_error_string(ERR_get_error(), ssl_errstring);
1598 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1602 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1604 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1606 ERR_error_string(ERR_get_error(), ssl_errstring);
1607 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1618 /*************************************************
1619 * Report the library versions. *
1620 *************************************************/
1622 /* There have historically been some issues with binary compatibility in
1623 OpenSSL libraries; if Exim (like many other applications) is built against
1624 one version of OpenSSL but the run-time linker picks up another version,
1625 it can result in serious failures, including crashing with a SIGSEGV. So
1626 report the version found by the compiler and the run-time version.
1628 Arguments: a FILE* to print the results to
1633 tls_version_report(FILE *f)
1635 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1637 OPENSSL_VERSION_TEXT,
1638 SSLeay_version(SSLEAY_VERSION));
1644 /*************************************************
1645 * Random number generation *
1646 *************************************************/
1648 /* Pseudo-random number generation. The result is not expected to be
1649 cryptographically strong but not so weak that someone will shoot themselves
1650 in the foot using it as a nonce in input in some email header scheme or
1651 whatever weirdness they'll twist this into. The result should handle fork()
1652 and avoid repeating sequences. OpenSSL handles that for us.
1656 Returns a random number in range [0, max-1]
1660 vaguely_random_number(int max)
1665 uschar smallbuf[sizeof(r)];
1670 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1674 gettimeofday(&r.tv, NULL);
1677 RAND_seed((uschar *)(&r), sizeof(r));
1679 /* We're after pseudo-random, not random; if we still don't have enough data
1680 in the internal PRNG then our options are limited. We could sleep and hope
1681 for entropy to come along (prayer technique) but if the system is so depleted
1682 in the first place then something is likely to just keep taking it. Instead,
1683 we'll just take whatever little bit of pseudo-random we can still manage to
1686 needed_len = sizeof(r);
1687 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1688 asked for a number less than 10. */
1689 for (r = max, i = 0; r; ++i)
1695 /* We do not care if crypto-strong */
1696 i = RAND_pseudo_bytes(smallbuf, needed_len);
1700 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
1701 return vaguely_random_number_fallback(max);
1705 for (p = smallbuf; needed_len; --needed_len, ++p)
1711 /* We don't particularly care about weighted results; if someone wants
1712 smooth distribution and cares enough then they should submit a patch then. */
1719 /*************************************************
1720 * OpenSSL option parse *
1721 *************************************************/
1723 /* Parse one option for tls_openssl_options_parse below
1726 name one option name
1727 value place to store a value for it
1728 Returns success or failure in parsing
1731 struct exim_openssl_option {
1735 /* We could use a macro to expand, but we need the ifdef and not all the
1736 options document which version they were introduced in. Policylet: include
1737 all options unless explicitly for DTLS, let the administrator choose which
1740 This list is current as of:
1742 static struct exim_openssl_option exim_openssl_options[] = {
1743 /* KEEP SORTED ALPHABETICALLY! */
1745 { US"all", SSL_OP_ALL },
1747 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
1748 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
1750 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
1751 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
1753 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1754 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
1756 #ifdef SSL_OP_EPHEMERAL_RSA
1757 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
1759 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
1760 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
1762 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
1763 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
1765 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
1766 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
1768 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
1769 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
1771 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
1772 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
1774 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
1775 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
1777 #ifdef SSL_OP_NO_COMPRESSION
1778 { US"no_compression", SSL_OP_NO_COMPRESSION },
1780 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
1781 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
1783 #ifdef SSL_OP_NO_SSLv2
1784 { US"no_sslv2", SSL_OP_NO_SSLv2 },
1786 #ifdef SSL_OP_NO_SSLv3
1787 { US"no_sslv3", SSL_OP_NO_SSLv3 },
1789 #ifdef SSL_OP_NO_TICKET
1790 { US"no_ticket", SSL_OP_NO_TICKET },
1792 #ifdef SSL_OP_NO_TLSv1
1793 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
1795 #ifdef SSL_OP_NO_TLSv1_1
1796 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
1797 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
1798 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
1800 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
1803 #ifdef SSL_OP_NO_TLSv1_2
1804 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
1806 #ifdef SSL_OP_SINGLE_DH_USE
1807 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
1809 #ifdef SSL_OP_SINGLE_ECDH_USE
1810 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
1812 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
1813 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
1815 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
1816 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
1818 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
1819 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
1821 #ifdef SSL_OP_TLS_D5_BUG
1822 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
1824 #ifdef SSL_OP_TLS_ROLLBACK_BUG
1825 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
1828 static int exim_openssl_options_size =
1829 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
1833 tls_openssl_one_option_parse(uschar *name, long *value)
1836 int last = exim_openssl_options_size;
1837 while (last > first)
1839 int middle = (first + last)/2;
1840 int c = Ustrcmp(name, exim_openssl_options[middle].name);
1843 *value = exim_openssl_options[middle].value;
1857 /*************************************************
1858 * OpenSSL option parsing logic *
1859 *************************************************/
1861 /* OpenSSL has a number of compatibility options which an administrator might
1862 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
1863 we look like log_selector.
1866 option_spec the administrator-supplied string of options
1867 results ptr to long storage for the options bitmap
1868 Returns success or failure
1872 tls_openssl_options_parse(uschar *option_spec, long *results)
1877 BOOL adding, item_parsed;
1880 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
1881 * from default because it increases BEAST susceptibility. */
1882 #ifdef SSL_OP_NO_SSLv2
1883 result |= SSL_OP_NO_SSLv2;
1886 if (option_spec == NULL)
1892 for (s=option_spec; *s != '\0'; /**/)
1894 while (isspace(*s)) ++s;
1897 if (*s != '+' && *s != '-')
1899 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
1900 "+ or - expected but found \"%s\"\n", s);
1903 adding = *s++ == '+';
1904 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
1907 item_parsed = tls_openssl_one_option_parse(s, &item);
1910 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
1913 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
1914 adding ? "adding" : "removing", result, item, s);
1927 /* End of tls-openssl.c */