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 static SSL_CTX *ctx_sni = NULL;
50 static SSL *ssl = NULL;
52 static char ssl_errstring[256];
54 static int ssl_session_timeout = 200;
55 static BOOL verify_optional = FALSE;
57 static BOOL reexpand_tls_files_for_sni = FALSE;
60 typedef struct tls_ext_ctx_cb {
63 #ifdef EXPERIMENTAL_OCSP
65 uschar *ocsp_file_expanded;
66 OCSP_RESPONSE *ocsp_response;
69 /* these are cached from first expand */
70 uschar *server_cipher_list;
71 /* only passed down to tls_error: */
75 /* should figure out a cleanup of API to handle state preserved per
76 implementation, for various reasons, which can be void * in the APIs.
77 For now, we hack around it. */
78 tls_ext_ctx_cb *static_cbinfo = NULL;
81 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional);
84 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
85 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
87 #ifdef EXPERIMENTAL_OCSP
88 static int tls_stapling_cb(SSL *s, void *arg);
92 /*************************************************
94 *************************************************/
96 /* Called from lots of places when errors occur before actually starting to do
97 the TLS handshake, that is, while the session is still in clear. Always returns
98 DEFER for a server and FAIL for a client so that most calls can use "return
99 tls_error(...)" to do this processing and then give an appropriate return. A
100 single function is used for both server and client, because it is called from
101 some shared functions.
104 prefix text to include in the logged error
105 host NULL if setting up a server;
106 the connected host if setting up a client
107 msg error message or NULL if we should ask OpenSSL
109 Returns: OK/DEFER/FAIL
113 tls_error(uschar *prefix, host_item *host, uschar *msg)
117 ERR_error_string(ERR_get_error(), ssl_errstring);
118 msg = (uschar *)ssl_errstring;
123 uschar *conn_info = smtp_get_connection_info();
124 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
126 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
127 conn_info, prefix, msg);
132 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
133 host->name, host->address, prefix, msg);
140 /*************************************************
141 * Callback to generate RSA key *
142 *************************************************/
150 Returns: pointer to generated key
154 rsa_callback(SSL *s, int export, int keylength)
157 export = export; /* Shut picky compilers up */
158 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
159 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
162 ERR_error_string(ERR_get_error(), ssl_errstring);
163 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
173 /*************************************************
174 * Callback for verification *
175 *************************************************/
177 /* The SSL library does certificate verification if set up to do so. This
178 callback has the current yes/no state is in "state". If verification succeeded,
179 we set up the tls_peerdn string. If verification failed, what happens depends
180 on whether the client is required to present a verifiable certificate or not.
182 If verification is optional, we change the state to yes, but still log the
183 verification error. For some reason (it really would help to have proper
184 documentation of OpenSSL), this callback function then gets called again, this
185 time with state = 1. In fact, that's useful, because we can set up the peerdn
186 value, but we must take care not to set the private verified flag on the second
189 Note: this function is not called if the client fails to present a certificate
190 when asked. We get here only if a certificate has been received. Handling of
191 optional verification for this case is done when requesting SSL to verify, by
192 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
195 state current yes/no state as 1/0
196 x509ctx certificate information.
198 Returns: 1 if verified, 0 if not
202 verify_callback(int state, X509_STORE_CTX *x509ctx)
204 static uschar txt[256];
206 X509_NAME_oneline(X509_get_subject_name(x509ctx->current_cert),
207 CS txt, sizeof(txt));
211 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
212 x509ctx->error_depth,
213 X509_verify_cert_error_string(x509ctx->error),
215 tls_certificate_verified = FALSE;
216 verify_callback_called = TRUE;
217 if (!verify_optional) return 0; /* reject */
218 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
219 "tls_try_verify_hosts)\n");
220 return 1; /* accept */
223 if (x509ctx->error_depth != 0)
225 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d cert=%s\n",
226 x509ctx->error_depth, txt);
230 DEBUG(D_tls) debug_printf("SSL%s peer: %s\n",
231 verify_callback_called? "" : " authenticated", txt);
235 if (!verify_callback_called) tls_certificate_verified = TRUE;
236 verify_callback_called = TRUE;
238 return 1; /* accept */
243 /*************************************************
244 * Information callback *
245 *************************************************/
247 /* The SSL library functions call this from time to time to indicate what they
248 are doing. We copy the string to the debugging output when TLS debugging has
260 info_callback(SSL *s, int where, int ret)
264 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
269 /*************************************************
270 * Initialize for DH *
271 *************************************************/
273 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
276 dhparam DH parameter file
277 host connected host, if client; NULL if server
279 Returns: TRUE if OK (nothing to set up, or setup worked)
283 init_dh(uschar *dhparam, host_item *host)
290 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
293 if (dhexpanded == NULL) return TRUE;
295 if ((bio = BIO_new_file(CS dhexpanded, "r")) == NULL)
297 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
298 host, (uschar *)strerror(errno));
303 if ((dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)) == NULL)
305 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
311 if ((8*DH_size(dh)) > tls_dh_max_bits)
314 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
315 8*DH_size(dh), tls_dh_max_bits);
319 SSL_CTX_set_tmp_dh(ctx, dh);
321 debug_printf("Diffie-Hellman initialized from %s with %d-bit key\n",
322 dhexpanded, 8*DH_size(dh));
335 #ifdef EXPERIMENTAL_OCSP
336 /*************************************************
337 * Load OCSP information into state *
338 *************************************************/
340 /* Called to load the OCSP response from the given file into memory, once
341 caller has determined this is needed. Checks validity. Debugs a message
344 ASSUMES: single response, for single cert.
347 sctx the SSL_CTX* to update
348 cbinfo various parts of session state
349 expanded the filename putatively holding an OCSP response
354 ocsp_load_response(SSL_CTX *sctx,
355 tls_ext_ctx_cb *cbinfo,
356 const uschar *expanded)
360 OCSP_BASICRESP *basic_response;
361 OCSP_SINGLERESP *single_response;
362 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
364 unsigned long verify_flags;
365 int status, reason, i;
367 cbinfo->ocsp_file_expanded = string_copy(expanded);
368 if (cbinfo->ocsp_response)
370 OCSP_RESPONSE_free(cbinfo->ocsp_response);
371 cbinfo->ocsp_response = NULL;
374 bio = BIO_new_file(CS cbinfo->ocsp_file_expanded, "rb");
377 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
378 cbinfo->ocsp_file_expanded);
382 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
386 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
390 status = OCSP_response_status(resp);
391 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
393 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
394 OCSP_response_status_str(status), status);
398 basic_response = OCSP_response_get1_basic(resp);
402 debug_printf("OCSP response parse error: unable to extract basic response.\n");
406 store = SSL_CTX_get_cert_store(sctx);
407 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
409 /* May need to expose ability to adjust those flags?
410 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
411 OCSP_TRUSTOTHER OCSP_NOINTERN */
413 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
417 ERR_error_string(ERR_get_error(), ssl_errstring);
418 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
423 /* Here's the simplifying assumption: there's only one response, for the
424 one certificate we use, and nothing for anything else in a chain. If this
425 proves false, we need to extract a cert id from our issued cert
426 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
427 right cert in the stack and then calls OCSP_single_get0_status()).
429 I'm hoping to avoid reworking a bunch more of how we handle state here. */
430 single_response = OCSP_resp_get0(basic_response, 0);
431 if (!single_response)
434 debug_printf("Unable to get first response from OCSP basic response.\n");
438 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
439 /* how does this status differ from the one above? */
440 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
442 DEBUG(D_tls) debug_printf("OCSP response not valid (take 2): %s (%d)\n",
443 OCSP_response_status_str(status), status);
447 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
449 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
453 cbinfo->ocsp_response = resp;
460 /*************************************************
461 * Expand key and cert file specs *
462 *************************************************/
464 /* Called once during tls_init and possibly againt during TLS setup, for a
465 new context, if Server Name Indication was used and tls_sni was seen in
466 the certificate string.
469 sctx the SSL_CTX* to update
470 cbinfo various parts of session state
472 Returns: OK/DEFER/FAIL
476 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
480 if (cbinfo->certificate == NULL)
483 if (Ustrstr(cbinfo->certificate, US"tls_sni"))
484 reexpand_tls_files_for_sni = TRUE;
486 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
489 if (expanded != NULL)
491 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
492 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
493 return tls_error(string_sprintf(
494 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
498 if (cbinfo->privatekey != NULL &&
499 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
502 /* If expansion was forced to fail, key_expanded will be NULL. If the result
503 of the expansion is an empty string, ignore it also, and assume the private
504 key is in the same file as the certificate. */
506 if (expanded != NULL && *expanded != 0)
508 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
509 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
510 return tls_error(string_sprintf(
511 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
514 #ifdef EXPERIMENTAL_OCSP
515 if (cbinfo->ocsp_file != NULL)
517 if (!expand_check(cbinfo->ocsp_file, US"tls_ocsp_file", &expanded))
520 if (expanded != NULL && *expanded != 0)
522 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
523 if (cbinfo->ocsp_file_expanded &&
524 (Ustrcmp(expanded, cbinfo->ocsp_file_expanded) == 0))
527 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
529 ocsp_load_response(sctx, cbinfo, expanded);
541 /*************************************************
542 * Callback to handle SNI *
543 *************************************************/
545 /* Called when acting as server during the TLS session setup if a Server Name
546 Indication extension was sent by the client.
548 API documentation is OpenSSL s_server.c implementation.
551 s SSL* of the current session
552 ad unknown (part of OpenSSL API) (unused)
553 arg Callback of "our" registered data
555 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
558 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
560 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
562 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
563 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
565 int old_pool = store_pool;
568 return SSL_TLSEXT_ERR_OK;
570 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
571 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
573 /* Make the extension value available for expansion */
574 store_pool = POOL_PERM;
575 tls_sni = string_copy(US servername);
576 store_pool = old_pool;
578 if (!reexpand_tls_files_for_sni)
579 return SSL_TLSEXT_ERR_OK;
581 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
582 not confident that memcpy wouldn't break some internal reference counting.
583 Especially since there's a references struct member, which would be off. */
585 ctx_sni = SSL_CTX_new(SSLv23_server_method());
588 ERR_error_string(ERR_get_error(), ssl_errstring);
589 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
590 return SSL_TLSEXT_ERR_NOACK;
593 /* Not sure how many of these are actually needed, since SSL object
594 already exists. Might even need this selfsame callback, for reneg? */
596 SSL_CTX_set_info_callback(ctx_sni, SSL_CTX_get_info_callback(ctx));
597 SSL_CTX_set_mode(ctx_sni, SSL_CTX_get_mode(ctx));
598 SSL_CTX_set_options(ctx_sni, SSL_CTX_get_options(ctx));
599 SSL_CTX_set_timeout(ctx_sni, SSL_CTX_get_timeout(ctx));
600 SSL_CTX_set_tlsext_servername_callback(ctx_sni, tls_servername_cb);
601 SSL_CTX_set_tlsext_servername_arg(ctx_sni, cbinfo);
602 if (cbinfo->server_cipher_list)
603 SSL_CTX_set_cipher_list(ctx_sni, CS cbinfo->server_cipher_list);
604 #ifdef EXPERIMENTAL_OCSP
605 if (cbinfo->ocsp_file)
607 SSL_CTX_set_tlsext_status_cb(ctx_sni, tls_stapling_cb);
608 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
612 rc = setup_certs(ctx_sni, tls_verify_certificates, tls_crl, NULL, FALSE);
613 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
615 /* do this after setup_certs, because this can require the certs for verifying
617 rc = tls_expand_session_files(ctx_sni, cbinfo);
618 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
620 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
621 SSL_set_SSL_CTX(s, ctx_sni);
623 return SSL_TLSEXT_ERR_OK;
625 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
630 #ifdef EXPERIMENTAL_OCSP
631 /*************************************************
632 * Callback to handle OCSP Stapling *
633 *************************************************/
635 /* Called when acting as server during the TLS session setup if the client
636 requests OCSP information with a Certificate Status Request.
638 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
644 tls_stapling_cb(SSL *s, void *arg)
646 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
647 uschar *response_der;
648 int response_der_len;
650 DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.\n",
651 cbinfo->ocsp_response ? "have" : "lack");
652 if (!cbinfo->ocsp_response)
653 return SSL_TLSEXT_ERR_NOACK;
656 response_der_len = i2d_OCSP_RESPONSE(cbinfo->ocsp_response, &response_der);
657 if (response_der_len <= 0)
658 return SSL_TLSEXT_ERR_NOACK;
660 SSL_set_tlsext_status_ocsp_resp(ssl, response_der, response_der_len);
661 return SSL_TLSEXT_ERR_OK;
664 #endif /* EXPERIMENTAL_OCSP */
669 /*************************************************
670 * Initialize for TLS *
671 *************************************************/
673 /* Called from both server and client code, to do preliminary initialization of
677 host connected host, if client; NULL if server
678 dhparam DH parameter file
679 certificate certificate file
680 privatekey private key
681 addr address if client; NULL if server (for some randomness)
683 Returns: OK/DEFER/FAIL
687 tls_init(host_item *host, uschar *dhparam, uschar *certificate,
689 #ifdef EXPERIMENTAL_OCSP
697 tls_ext_ctx_cb *cbinfo;
699 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
700 cbinfo->certificate = certificate;
701 cbinfo->privatekey = privatekey;
702 #ifdef EXPERIMENTAL_OCSP
703 cbinfo->ocsp_file = ocsp_file;
705 cbinfo->dhparam = dhparam;
708 SSL_load_error_strings(); /* basic set up */
709 OpenSSL_add_ssl_algorithms();
711 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
712 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
713 list of available digests. */
714 EVP_add_digest(EVP_sha256());
717 /* Create a context */
719 ctx = SSL_CTX_new((host == NULL)?
720 SSLv23_server_method() : SSLv23_client_method());
722 if (ctx == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
724 /* It turns out that we need to seed the random number generator this early in
725 order to get the full complement of ciphers to work. It took me roughly a day
726 of work to discover this by experiment.
728 On systems that have /dev/urandom, SSL may automatically seed itself from
729 there. Otherwise, we have to make something up as best we can. Double check
735 gettimeofday(&r.tv, NULL);
738 RAND_seed((uschar *)(&r), sizeof(r));
739 RAND_seed((uschar *)big_buffer, big_buffer_size);
740 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
743 return tls_error(US"RAND_status", host,
744 US"unable to seed random number generator");
747 /* Set up the information callback, which outputs if debugging is at a suitable
750 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
752 /* Automatically re-try reads/writes after renegotiation. */
753 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
755 /* Apply administrator-supplied work-arounds.
756 Historically we applied just one requested option,
757 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
758 moved to an administrator-controlled list of options to specify and
759 grandfathered in the first one as the default value for "openssl_options".
761 No OpenSSL version number checks: the options we accept depend upon the
762 availability of the option value macros from OpenSSL. */
764 okay = tls_openssl_options_parse(openssl_options, &init_options);
766 return tls_error(US"openssl_options parsing failed", host, NULL);
770 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
771 if (!(SSL_CTX_set_options(ctx, init_options)))
772 return tls_error(string_sprintf(
773 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
776 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
778 /* Initialize with DH parameters if supplied */
780 if (!init_dh(dhparam, host)) return DEFER;
782 /* Set up certificate and key (and perhaps OCSP info) */
784 rc = tls_expand_session_files(ctx, cbinfo);
785 if (rc != OK) return rc;
787 /* If we need to handle SNI, do so */
788 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
791 #ifdef EXPERIMENTAL_OCSP
792 /* We check ocsp_file, not ocsp_response, because we care about if
793 the option exists, not what the current expansion might be, as SNI might
794 change the certificate and OCSP file in use between now and the time the
795 callback is invoked. */
796 if (cbinfo->ocsp_file)
798 SSL_CTX_set_tlsext_status_cb(ctx, tls_stapling_cb);
799 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
802 /* We always do this, so that $tls_sni is available even if not used in
804 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
805 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
809 /* Set up the RSA callback */
811 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
813 /* Finally, set the timeout, and we are done */
815 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
816 DEBUG(D_tls) debug_printf("Initialized TLS\n");
818 static_cbinfo = cbinfo;
826 /*************************************************
827 * Get name of cipher in use *
828 *************************************************/
830 /* The answer is left in a static buffer, and tls_cipher is set to point
833 Argument: pointer to an SSL structure for the connection
838 construct_cipher_name(SSL *ssl)
840 static uschar cipherbuf[256];
841 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
842 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
843 the accessor functions use const in the prototype. */
847 switch (ssl->session->ssl_version)
861 #ifdef TLS1_1_VERSION
867 #ifdef TLS1_2_VERSION
877 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
878 SSL_CIPHER_get_bits(c, &tls_bits);
880 string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
881 SSL_CIPHER_get_name(c), tls_bits);
882 tls_cipher = cipherbuf;
884 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
891 /*************************************************
892 * Set up for verifying certificates *
893 *************************************************/
895 /* Called by both client and server startup
898 sctx SSL_CTX* to initialise
899 certs certs file or NULL
901 host NULL in a server; the remote host in a client
902 optional TRUE if called from a server for a host in tls_try_verify_hosts;
903 otherwise passed as FALSE
905 Returns: OK/DEFER/FAIL
909 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional)
911 uschar *expcerts, *expcrl;
913 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
916 if (expcerts != NULL)
919 if (!SSL_CTX_set_default_verify_paths(sctx))
920 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
922 if (Ustat(expcerts, &statbuf) < 0)
924 log_write(0, LOG_MAIN|LOG_PANIC,
925 "failed to stat %s for certificates", expcerts);
931 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
932 { file = NULL; dir = expcerts; }
934 { file = expcerts; dir = NULL; }
936 /* If a certificate file is empty, the next function fails with an
937 unhelpful error message. If we skip it, we get the correct behaviour (no
938 certificates are recognized, but the error message is still misleading (it
939 says no certificate was supplied.) But this is better. */
941 if ((file == NULL || statbuf.st_size > 0) &&
942 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
943 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
947 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
951 /* Handle a certificate revocation list. */
953 #if OPENSSL_VERSION_NUMBER > 0x00907000L
955 /* This bit of code is now the version supplied by Lars Mainka. (I have
956 * merely reformatted it into the Exim code style.)
958 * "From here I changed the code to add support for multiple crl's
959 * in pem format in one file or to support hashed directory entries in
960 * pem format instead of a file. This method now uses the library function
961 * X509_STORE_load_locations to add the CRL location to the SSL context.
962 * OpenSSL will then handle the verify against CA certs and CRLs by
963 * itself in the verify callback." */
965 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
966 if (expcrl != NULL && *expcrl != 0)
968 struct stat statbufcrl;
969 if (Ustat(expcrl, &statbufcrl) < 0)
971 log_write(0, LOG_MAIN|LOG_PANIC,
972 "failed to stat %s for certificates revocation lists", expcrl);
977 /* is it a file or directory? */
979 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
980 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
984 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
990 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
992 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
993 return tls_error(US"X509_STORE_load_locations", host, NULL);
995 /* setting the flags to check against the complete crl chain */
997 X509_STORE_set_flags(cvstore,
998 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1002 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1004 /* If verification is optional, don't fail if no certificate */
1006 SSL_CTX_set_verify(sctx,
1007 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1016 /*************************************************
1017 * Start a TLS session in a server *
1018 *************************************************/
1020 /* This is called when Exim is running as a server, after having received
1021 the STARTTLS command. It must respond to that command, and then negotiate
1025 require_ciphers allowed ciphers
1027 Returns: OK on success
1028 DEFER for errors before the start of the negotiation
1029 FAIL for errors during the negotation; the server can't
1034 tls_server_start(const uschar *require_ciphers)
1038 tls_ext_ctx_cb *cbinfo;
1040 /* Check for previous activation */
1042 if (tls_active >= 0)
1044 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1045 smtp_printf("554 Already in TLS\r\n");
1049 /* Initialize the SSL library. If it fails, it will already have logged
1052 rc = tls_init(NULL, tls_dhparam, tls_certificate, tls_privatekey,
1053 #ifdef EXPERIMENTAL_OCSP
1057 if (rc != OK) return rc;
1058 cbinfo = static_cbinfo;
1060 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1063 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1064 were historically separated by underscores. So that I can use either form in my
1065 tests, and also for general convenience, we turn underscores into hyphens here.
1068 if (expciphers != NULL)
1070 uschar *s = expciphers;
1071 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1072 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1073 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1074 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1075 cbinfo->server_cipher_list = expciphers;
1078 /* If this is a host for which certificate verification is mandatory or
1079 optional, set up appropriately. */
1081 tls_certificate_verified = FALSE;
1082 verify_callback_called = FALSE;
1084 if (verify_check_host(&tls_verify_hosts) == OK)
1086 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, FALSE);
1087 if (rc != OK) return rc;
1088 verify_optional = FALSE;
1090 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1092 rc = setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, TRUE);
1093 if (rc != OK) return rc;
1094 verify_optional = TRUE;
1097 /* Prepare for new connection */
1099 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1101 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1103 * With the SSL_clear(), we get strange interoperability bugs with
1104 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1105 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1107 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1108 * session shutdown. In this case, we have a brand new object and there's no
1109 * obvious reason to immediately clear it. I'm guessing that this was
1110 * originally added because of incomplete initialisation which the clear fixed,
1111 * in some historic release.
1114 /* Set context and tell client to go ahead, except in the case of TLS startup
1115 on connection, where outputting anything now upsets the clients and tends to
1116 make them disconnect. We need to have an explicit fflush() here, to force out
1117 the response. Other smtp_printf() calls do not need it, because in non-TLS
1118 mode, the fflush() happens when smtp_getc() is called. */
1120 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1121 if (!tls_on_connect)
1123 smtp_printf("220 TLS go ahead\r\n");
1127 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1128 that the OpenSSL library doesn't. */
1130 SSL_set_wfd(ssl, fileno(smtp_out));
1131 SSL_set_rfd(ssl, fileno(smtp_in));
1132 SSL_set_accept_state(ssl);
1134 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1136 sigalrm_seen = FALSE;
1137 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1138 rc = SSL_accept(ssl);
1143 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1144 if (ERR_get_error() == 0)
1145 log_write(0, LOG_MAIN,
1146 "TLS client disconnected cleanly (rejected our certificate?)");
1150 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1152 /* TLS has been set up. Adjust the input functions to read via TLS,
1153 and initialize things. */
1155 construct_cipher_name(ssl);
1160 if (SSL_get_shared_ciphers(ssl, CS buf, sizeof(buf)) != NULL)
1161 debug_printf("Shared ciphers: %s\n", buf);
1165 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1166 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1167 ssl_xfer_eof = ssl_xfer_error = 0;
1169 receive_getc = tls_getc;
1170 receive_ungetc = tls_ungetc;
1171 receive_feof = tls_feof;
1172 receive_ferror = tls_ferror;
1173 receive_smtp_buffered = tls_smtp_buffered;
1175 tls_active = fileno(smtp_out);
1183 /*************************************************
1184 * Start a TLS session in a client *
1185 *************************************************/
1187 /* Called from the smtp transport after STARTTLS has been accepted.
1190 fd the fd of the connection
1191 host connected host (for messages)
1192 addr the first address
1193 dhparam DH parameter file
1194 certificate certificate file
1195 privatekey private key file
1196 sni TLS SNI to send to remote host
1197 verify_certs file for certificate verify
1198 crl file containing CRL
1199 require_ciphers list of allowed ciphers
1200 timeout startup timeout
1202 Returns: OK on success
1203 FAIL otherwise - note that tls_error() will not give DEFER
1204 because this is not a server
1208 tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
1209 uschar *certificate, uschar *privatekey, uschar *sni,
1210 uschar *verify_certs, uschar *crl,
1211 uschar *require_ciphers, int timeout)
1213 static uschar txt[256];
1218 rc = tls_init(host, dhparam, certificate, privatekey,
1219 #ifdef EXPERIMENTAL_OCSP
1223 if (rc != OK) return rc;
1225 tls_certificate_verified = FALSE;
1226 verify_callback_called = FALSE;
1228 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1231 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1232 are separated by underscores. So that I can use either form in my tests, and
1233 also for general convenience, we turn underscores into hyphens here. */
1235 if (expciphers != NULL)
1237 uschar *s = expciphers;
1238 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1239 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1240 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1241 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1244 rc = setup_certs(ctx, verify_certs, crl, host, FALSE);
1245 if (rc != OK) return rc;
1247 if ((ssl = SSL_new(ctx)) == NULL) return tls_error(US"SSL_new", host, NULL);
1248 SSL_set_session_id_context(ssl, sid_ctx, Ustrlen(sid_ctx));
1249 SSL_set_fd(ssl, fd);
1250 SSL_set_connect_state(ssl);
1254 if (!expand_check(sni, US"tls_sni", &tls_sni))
1256 if (!Ustrlen(tls_sni))
1260 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_sni);
1261 SSL_set_tlsext_host_name(ssl, tls_sni);
1265 /* There doesn't seem to be a built-in timeout on connection. */
1267 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1268 sigalrm_seen = FALSE;
1270 rc = SSL_connect(ssl);
1274 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1276 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1278 /* Beware anonymous ciphers which lead to server_cert being NULL */
1279 server_cert = SSL_get_peer_certificate (ssl);
1282 tls_peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1283 CS txt, sizeof(txt));
1289 construct_cipher_name(ssl); /* Sets tls_cipher */
1299 /*************************************************
1300 * TLS version of getc *
1301 *************************************************/
1303 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1304 it refills the buffer via the SSL reading function.
1307 Returns: the next character or EOF
1313 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
1318 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1319 ssl_xfer_buffer, ssl_xfer_buffer_size);
1321 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1322 inbytes = SSL_read(ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
1323 error = SSL_get_error(ssl, inbytes);
1326 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
1327 closed down, not that the socket itself has been closed down. Revert to
1328 non-SSL handling. */
1330 if (error == SSL_ERROR_ZERO_RETURN)
1332 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1334 receive_getc = smtp_getc;
1335 receive_ungetc = smtp_ungetc;
1336 receive_feof = smtp_feof;
1337 receive_ferror = smtp_ferror;
1338 receive_smtp_buffered = smtp_buffered;
1351 /* Handle genuine errors */
1353 else if (error == SSL_ERROR_SSL)
1355 ERR_error_string(ERR_get_error(), ssl_errstring);
1356 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
1361 else if (error != SSL_ERROR_NONE)
1363 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
1368 #ifndef DISABLE_DKIM
1369 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
1371 ssl_xfer_buffer_hwm = inbytes;
1372 ssl_xfer_buffer_lwm = 0;
1375 /* Something in the buffer; return next uschar */
1377 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
1382 /*************************************************
1383 * Read bytes from TLS channel *
1384 *************************************************/
1391 Returns: the number of bytes read
1392 -1 after a failed read
1396 tls_read(uschar *buff, size_t len)
1401 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
1402 buff, (unsigned int)len);
1404 inbytes = SSL_read(ssl, CS buff, len);
1405 error = SSL_get_error(ssl, inbytes);
1407 if (error == SSL_ERROR_ZERO_RETURN)
1409 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
1412 else if (error != SSL_ERROR_NONE)
1424 /*************************************************
1425 * Write bytes down TLS channel *
1426 *************************************************/
1433 Returns: the number of bytes after a successful write,
1434 -1 after a failed write
1438 tls_write(const uschar *buff, size_t len)
1444 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
1447 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
1448 outbytes = SSL_write(ssl, CS buff, left);
1449 error = SSL_get_error(ssl, outbytes);
1450 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
1454 ERR_error_string(ERR_get_error(), ssl_errstring);
1455 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
1458 case SSL_ERROR_NONE:
1463 case SSL_ERROR_ZERO_RETURN:
1464 log_write(0, LOG_MAIN, "SSL channel closed on write");
1468 log_write(0, LOG_MAIN, "SSL_write error %d", error);
1477 /*************************************************
1478 * Close down a TLS session *
1479 *************************************************/
1481 /* This is also called from within a delivery subprocess forked from the
1482 daemon, to shut down the TLS library, without actually doing a shutdown (which
1483 would tamper with the SSL session in the parent process).
1485 Arguments: TRUE if SSL_shutdown is to be called
1490 tls_close(BOOL shutdown)
1492 if (tls_active < 0) return; /* TLS was not active */
1496 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
1509 /*************************************************
1510 * Let tls_require_ciphers be checked at startup *
1511 *************************************************/
1513 /* The tls_require_ciphers option, if set, must be something which the
1516 Returns: NULL on success, or error message
1520 tls_validate_require_cipher(void)
1523 uschar *s, *expciphers, *err;
1525 /* this duplicates from tls_init(), we need a better "init just global
1526 state, for no specific purpose" singleton function of our own */
1528 SSL_load_error_strings();
1529 OpenSSL_add_ssl_algorithms();
1530 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1531 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1532 list of available digests. */
1533 EVP_add_digest(EVP_sha256());
1536 if (!(tls_require_ciphers && *tls_require_ciphers))
1539 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
1540 return US"failed to expand tls_require_ciphers";
1542 if (!(expciphers && *expciphers))
1545 /* normalisation ripped from above */
1547 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1551 ctx = SSL_CTX_new(SSLv23_server_method());
1554 ERR_error_string(ERR_get_error(), ssl_errstring);
1555 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
1559 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
1561 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
1563 ERR_error_string(ERR_get_error(), ssl_errstring);
1564 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
1575 /*************************************************
1576 * Report the library versions. *
1577 *************************************************/
1579 /* There have historically been some issues with binary compatibility in
1580 OpenSSL libraries; if Exim (like many other applications) is built against
1581 one version of OpenSSL but the run-time linker picks up another version,
1582 it can result in serious failures, including crashing with a SIGSEGV. So
1583 report the version found by the compiler and the run-time version.
1585 Arguments: a FILE* to print the results to
1590 tls_version_report(FILE *f)
1592 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
1594 OPENSSL_VERSION_TEXT,
1595 SSLeay_version(SSLEAY_VERSION));
1601 /*************************************************
1602 * Random number generation *
1603 *************************************************/
1605 /* Pseudo-random number generation. The result is not expected to be
1606 cryptographically strong but not so weak that someone will shoot themselves
1607 in the foot using it as a nonce in input in some email header scheme or
1608 whatever weirdness they'll twist this into. The result should handle fork()
1609 and avoid repeating sequences. OpenSSL handles that for us.
1613 Returns a random number in range [0, max-1]
1617 vaguely_random_number(int max)
1622 uschar smallbuf[sizeof(r)];
1627 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
1631 gettimeofday(&r.tv, NULL);
1634 RAND_seed((uschar *)(&r), sizeof(r));
1636 /* We're after pseudo-random, not random; if we still don't have enough data
1637 in the internal PRNG then our options are limited. We could sleep and hope
1638 for entropy to come along (prayer technique) but if the system is so depleted
1639 in the first place then something is likely to just keep taking it. Instead,
1640 we'll just take whatever little bit of pseudo-random we can still manage to
1643 needed_len = sizeof(r);
1644 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
1645 asked for a number less than 10. */
1646 for (r = max, i = 0; r; ++i)
1652 /* We do not care if crypto-strong */
1653 i = RAND_pseudo_bytes(smallbuf, needed_len);
1657 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
1658 return vaguely_random_number_fallback(max);
1662 for (p = smallbuf; needed_len; --needed_len, ++p)
1668 /* We don't particularly care about weighted results; if someone wants
1669 smooth distribution and cares enough then they should submit a patch then. */
1676 /*************************************************
1677 * OpenSSL option parse *
1678 *************************************************/
1680 /* Parse one option for tls_openssl_options_parse below
1683 name one option name
1684 value place to store a value for it
1685 Returns success or failure in parsing
1688 struct exim_openssl_option {
1692 /* We could use a macro to expand, but we need the ifdef and not all the
1693 options document which version they were introduced in. Policylet: include
1694 all options unless explicitly for DTLS, let the administrator choose which
1697 This list is current as of:
1699 static struct exim_openssl_option exim_openssl_options[] = {
1700 /* KEEP SORTED ALPHABETICALLY! */
1702 { US"all", SSL_OP_ALL },
1704 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
1705 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
1707 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
1708 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
1710 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
1711 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
1713 #ifdef SSL_OP_EPHEMERAL_RSA
1714 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
1716 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
1717 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
1719 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
1720 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
1722 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
1723 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
1725 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
1726 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
1728 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
1729 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
1731 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
1732 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
1734 #ifdef SSL_OP_NO_COMPRESSION
1735 { US"no_compression", SSL_OP_NO_COMPRESSION },
1737 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
1738 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
1740 #ifdef SSL_OP_NO_SSLv2
1741 { US"no_sslv2", SSL_OP_NO_SSLv2 },
1743 #ifdef SSL_OP_NO_SSLv3
1744 { US"no_sslv3", SSL_OP_NO_SSLv3 },
1746 #ifdef SSL_OP_NO_TICKET
1747 { US"no_ticket", SSL_OP_NO_TICKET },
1749 #ifdef SSL_OP_NO_TLSv1
1750 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
1752 #ifdef SSL_OP_NO_TLSv1_1
1753 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
1754 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
1755 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
1757 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
1760 #ifdef SSL_OP_NO_TLSv1_2
1761 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
1763 #ifdef SSL_OP_SINGLE_DH_USE
1764 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
1766 #ifdef SSL_OP_SINGLE_ECDH_USE
1767 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
1769 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
1770 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
1772 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
1773 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
1775 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
1776 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
1778 #ifdef SSL_OP_TLS_D5_BUG
1779 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
1781 #ifdef SSL_OP_TLS_ROLLBACK_BUG
1782 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
1785 static int exim_openssl_options_size =
1786 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
1790 tls_openssl_one_option_parse(uschar *name, long *value)
1793 int last = exim_openssl_options_size;
1794 while (last > first)
1796 int middle = (first + last)/2;
1797 int c = Ustrcmp(name, exim_openssl_options[middle].name);
1800 *value = exim_openssl_options[middle].value;
1814 /*************************************************
1815 * OpenSSL option parsing logic *
1816 *************************************************/
1818 /* OpenSSL has a number of compatibility options which an administrator might
1819 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
1820 we look like log_selector.
1823 option_spec the administrator-supplied string of options
1824 results ptr to long storage for the options bitmap
1825 Returns success or failure
1829 tls_openssl_options_parse(uschar *option_spec, long *results)
1834 BOOL adding, item_parsed;
1837 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
1838 * from default because it increases BEAST susceptibility. */
1840 if (option_spec == NULL)
1846 for (s=option_spec; *s != '\0'; /**/)
1848 while (isspace(*s)) ++s;
1851 if (*s != '+' && *s != '-')
1853 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
1854 "+ or - expected but found \"%s\"\n", s);
1857 adding = *s++ == '+';
1858 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
1861 item_parsed = tls_openssl_one_option_parse(s, &item);
1864 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
1867 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
1868 adding ? "adding" : "removing", result, item, s);
1881 /* End of tls-openssl.c */