1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2014 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Portions Copyright (c) The OpenSSL Project 1999 */
10 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11 library. It is #included into the tls.c file when that library is used. The
12 code herein is based on a patch that was originally contributed by Steve
13 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
15 No cryptographic code is included in Exim. All this module does is to call
16 functions from the OpenSSL library. */
21 #include <openssl/lhash.h>
22 #include <openssl/ssl.h>
23 #include <openssl/err.h>
24 #include <openssl/rand.h>
26 # include <openssl/ocsp.h>
28 #ifdef EXPERIMENTAL_DANE
34 # define EXIM_OCSP_SKEW_SECONDS (300L)
35 # define EXIM_OCSP_MAX_AGE (-1L)
38 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
39 # define EXIM_HAVE_OPENSSL_TLSEXT
41 #if OPENSSL_VERSION_NUMBER >= 0x010100000L
42 # define EXIM_HAVE_OPENSSL_CHECKHOST
44 #if OPENSSL_VERSION_NUMBER >= 0x010000000L \
45 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
46 # define EXIM_HAVE_OPENSSL_CHECKHOST
49 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
50 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
54 /* Structure for collecting random data for seeding. */
56 typedef struct randstuff {
61 /* Local static variables */
63 static BOOL client_verify_callback_called = FALSE;
64 static BOOL server_verify_callback_called = FALSE;
65 static const uschar *sid_ctx = US"exim";
67 /* We have three different contexts to care about.
69 Simple case: client, `client_ctx`
70 As a client, we can be doing a callout or cut-through delivery while receiving
71 a message. So we have a client context, which should have options initialised
72 from the SMTP Transport.
75 There are two cases: with and without ServerNameIndication from the client.
76 Given TLS SNI, we can be using different keys, certs and various other
77 configuration settings, because they're re-expanded with $tls_sni set. This
78 allows vhosting with TLS. This SNI is sent in the handshake.
79 A client might not send SNI, so we need a fallback, and an initial setup too.
80 So as a server, we start out using `server_ctx`.
81 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
82 `server_sni` from `server_ctx` and then initialise settings by re-expanding
86 static SSL_CTX *client_ctx = NULL;
87 static SSL_CTX *server_ctx = NULL;
88 static SSL *client_ssl = NULL;
89 static SSL *server_ssl = NULL;
91 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
92 static SSL_CTX *server_sni = NULL;
95 static char ssl_errstring[256];
97 static int ssl_session_timeout = 200;
98 static BOOL client_verify_optional = FALSE;
99 static BOOL server_verify_optional = FALSE;
101 static BOOL reexpand_tls_files_for_sni = FALSE;
104 typedef struct tls_ext_ctx_cb {
112 uschar *file_expanded;
113 OCSP_RESPONSE *response;
116 X509_STORE *verify_store; /* non-null if status requested */
117 BOOL verify_required;
122 /* these are cached from first expand */
123 uschar *server_cipher_list;
124 /* only passed down to tls_error: */
126 uschar * verify_cert_hostnames;
127 #ifdef EXPERIMENTAL_EVENT
128 uschar * event_action;
132 /* should figure out a cleanup of API to handle state preserved per
133 implementation, for various reasons, which can be void * in the APIs.
134 For now, we hack around it. */
135 tls_ext_ctx_cb *client_static_cbinfo = NULL;
136 tls_ext_ctx_cb *server_static_cbinfo = NULL;
139 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
140 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
143 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
144 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
147 static int tls_server_stapling_cb(SSL *s, void *arg);
151 /*************************************************
153 *************************************************/
155 /* Called from lots of places when errors occur before actually starting to do
156 the TLS handshake, that is, while the session is still in clear. Always returns
157 DEFER for a server and FAIL for a client so that most calls can use "return
158 tls_error(...)" to do this processing and then give an appropriate return. A
159 single function is used for both server and client, because it is called from
160 some shared functions.
163 prefix text to include in the logged error
164 host NULL if setting up a server;
165 the connected host if setting up a client
166 msg error message or NULL if we should ask OpenSSL
168 Returns: OK/DEFER/FAIL
172 tls_error(uschar * prefix, const host_item * host, uschar * msg)
176 ERR_error_string(ERR_get_error(), ssl_errstring);
177 msg = (uschar *)ssl_errstring;
182 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
183 host->name, host->address, prefix, msg);
188 uschar *conn_info = smtp_get_connection_info();
189 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
191 /* I'd like to get separated H= here, but too hard for now */
192 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
193 conn_info, prefix, msg);
200 /*************************************************
201 * Callback to generate RSA key *
202 *************************************************/
210 Returns: pointer to generated key
214 rsa_callback(SSL *s, int export, int keylength)
217 export = export; /* Shut picky compilers up */
218 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
219 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
222 ERR_error_string(ERR_get_error(), ssl_errstring);
223 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
235 x509_store_dump_cert_s_names(X509_STORE * store)
237 STACK_OF(X509_OBJECT) * roots= store->objs;
239 static uschar name[256];
241 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
243 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
244 if(tmp_obj->type == X509_LU_X509)
246 X509 * current_cert= tmp_obj->data.x509;
247 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
248 debug_printf(" %s\n", name);
256 /*************************************************
257 * Callback for verification *
258 *************************************************/
260 /* The SSL library does certificate verification if set up to do so. This
261 callback has the current yes/no state is in "state". If verification succeeded,
262 we set up the tls_peerdn string. If verification failed, what happens depends
263 on whether the client is required to present a verifiable certificate or not.
265 If verification is optional, we change the state to yes, but still log the
266 verification error. For some reason (it really would help to have proper
267 documentation of OpenSSL), this callback function then gets called again, this
268 time with state = 1. In fact, that's useful, because we can set up the peerdn
269 value, but we must take care not to set the private verified flag on the second
272 Note: this function is not called if the client fails to present a certificate
273 when asked. We get here only if a certificate has been received. Handling of
274 optional verification for this case is done when requesting SSL to verify, by
275 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
277 May be called multiple times for different issues with a certificate, even
278 for a given "depth" in the certificate chain.
281 state current yes/no state as 1/0
282 x509ctx certificate information.
283 client TRUE for client startup, FALSE for server startup
285 Returns: 1 if verified, 0 if not
289 verify_callback(int state, X509_STORE_CTX *x509ctx,
290 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
292 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
293 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
294 static uschar txt[256];
295 #ifdef EXPERIMENTAL_EVENT
300 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
304 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
306 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
311 tlsp->peercert = X509_dup(cert);
312 return 0; /* reject */
314 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
315 "tls_try_verify_hosts)\n");
320 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
322 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
323 { /* client, wanting stapling */
324 /* Add the server cert's signing chain as the one
325 for the verification of the OCSP stapled information. */
327 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
332 #ifdef EXPERIMENTAL_EVENT
333 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
336 tlsp->peercert = X509_dup(cert);
337 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
339 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
340 "depth=%d cert=%s: %s", depth, txt, yield);
343 return 0; /* reject */
344 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
345 "(host in tls_try_verify_hosts)\n");
347 X509_free(tlsp->peercert);
348 tlsp->peercert = NULL;
354 uschar * verify_cert_hostnames;
357 tlsp->peercert = X509_dup(cert);
359 if ( tlsp == &tls_out
360 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
361 /* client, wanting hostname check */
363 # if EXIM_HAVE_OPENSSL_CHECKHOST
364 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
365 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
367 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
368 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
372 uschar * list = verify_cert_hostnames;
375 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
376 if ((rc = X509_check_host(cert, name, 0,
377 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
378 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS)))
382 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
389 log_write(0, LOG_MAIN,
390 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
393 return 0; /* reject */
394 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
395 "tls_try_verify_hosts)\n");
399 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
401 log_write(0, LOG_MAIN,
402 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
405 return 0; /* reject */
406 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
407 "tls_try_verify_hosts)\n");
411 #ifdef EXPERIMENTAL_EVENT
412 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
414 if ((yield = event_raise(ev, US"tls:cert", US"0")))
416 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
417 "depth=0 cert=%s: %s", txt, yield);
420 return 0; /* reject */
421 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
422 "(host in tls_try_verify_hosts)\n");
426 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
427 *calledp ? "" : " authenticated", txt);
428 if (!*calledp) tlsp->certificate_verified = TRUE;
432 return 1; /* accept, at least for this level */
436 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
438 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
442 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
444 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
448 #ifdef EXPERIMENTAL_DANE
450 /* This gets called *by* the dane library verify callback, which interposes
454 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
456 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
457 static uschar txt[256];
458 #ifdef EXPERIMENTAL_EVENT
459 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
463 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
465 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
466 tls_out.peerdn = txt;
467 tls_out.peercert = X509_dup(cert);
469 #ifdef EXPERIMENTAL_EVENT
470 if (client_static_cbinfo->event_action)
472 if ((yield = event_raise(client_static_cbinfo->event_action,
473 US"tls:cert", string_sprintf("%d", depth))))
475 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
476 "depth=%d cert=%s: %s", depth, txt, yield);
477 tls_out.certificate_verified = FALSE;
478 return 0; /* reject */
482 X509_free(tls_out.peercert);
483 tls_out.peercert = NULL;
489 tls_out.dane_verified =
490 tls_out.certificate_verified = TRUE;
494 #endif /*EXPERIMENTAL_DANE*/
497 /*************************************************
498 * Information callback *
499 *************************************************/
501 /* The SSL library functions call this from time to time to indicate what they
502 are doing. We copy the string to the debugging output when TLS debugging has
514 info_callback(SSL *s, int where, int ret)
518 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
523 /*************************************************
524 * Initialize for DH *
525 *************************************************/
527 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
530 dhparam DH parameter file or fixed parameter identity string
531 host connected host, if client; NULL if server
533 Returns: TRUE if OK (nothing to set up, or setup worked)
537 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host)
544 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
547 if (!dhexpanded || !*dhexpanded)
548 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
549 else if (dhexpanded[0] == '/')
551 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
553 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
554 host, US strerror(errno));
560 if (Ustrcmp(dhexpanded, "none") == 0)
562 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
566 if (!(pem = std_dh_prime_named(dhexpanded)))
568 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
569 host, US strerror(errno));
572 bio = BIO_new_mem_buf(CS pem, -1);
575 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
578 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
583 /* Even if it is larger, we silently return success rather than cause things
584 * to fail out, so that a too-large DH will not knock out all TLS; it's a
585 * debatable choice. */
586 if ((8*DH_size(dh)) > tls_dh_max_bits)
589 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
590 8*DH_size(dh), tls_dh_max_bits);
594 SSL_CTX_set_tmp_dh(sctx, dh);
596 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
597 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
610 /*************************************************
611 * Load OCSP information into state *
612 *************************************************/
614 /* Called to load the server OCSP response from the given file into memory, once
615 caller has determined this is needed. Checks validity. Debugs a message
618 ASSUMES: single response, for single cert.
621 sctx the SSL_CTX* to update
622 cbinfo various parts of session state
623 expanded the filename putatively holding an OCSP response
628 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
632 OCSP_BASICRESP *basic_response;
633 OCSP_SINGLERESP *single_response;
634 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
636 unsigned long verify_flags;
637 int status, reason, i;
639 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
640 if (cbinfo->u_ocsp.server.response)
642 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
643 cbinfo->u_ocsp.server.response = NULL;
646 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
649 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
650 cbinfo->u_ocsp.server.file_expanded);
654 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
658 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
662 status = OCSP_response_status(resp);
663 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
665 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
666 OCSP_response_status_str(status), status);
670 basic_response = OCSP_response_get1_basic(resp);
674 debug_printf("OCSP response parse error: unable to extract basic response.\n");
678 store = SSL_CTX_get_cert_store(sctx);
679 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
681 /* May need to expose ability to adjust those flags?
682 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
683 OCSP_TRUSTOTHER OCSP_NOINTERN */
685 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
689 ERR_error_string(ERR_get_error(), ssl_errstring);
690 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
695 /* Here's the simplifying assumption: there's only one response, for the
696 one certificate we use, and nothing for anything else in a chain. If this
697 proves false, we need to extract a cert id from our issued cert
698 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
699 right cert in the stack and then calls OCSP_single_get0_status()).
701 I'm hoping to avoid reworking a bunch more of how we handle state here. */
702 single_response = OCSP_resp_get0(basic_response, 0);
703 if (!single_response)
706 debug_printf("Unable to get first response from OCSP basic response.\n");
710 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
711 if (status != V_OCSP_CERTSTATUS_GOOD)
713 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
714 OCSP_cert_status_str(status), status,
715 OCSP_crl_reason_str(reason), reason);
719 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
721 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
726 cbinfo->u_ocsp.server.response = resp;
730 if (running_in_test_harness)
732 extern char ** environ;
734 for (p = USS environ; *p != NULL; p++)
735 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
737 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
738 goto supply_response;
743 #endif /*!DISABLE_OCSP*/
748 /*************************************************
749 * Expand key and cert file specs *
750 *************************************************/
752 /* Called once during tls_init and possibly again during TLS setup, for a
753 new context, if Server Name Indication was used and tls_sni was seen in
754 the certificate string.
757 sctx the SSL_CTX* to update
758 cbinfo various parts of session state
760 Returns: OK/DEFER/FAIL
764 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
768 if (cbinfo->certificate == NULL)
771 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
772 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
773 Ustrstr(cbinfo->certificate, US"tls_out_sni")
775 reexpand_tls_files_for_sni = TRUE;
777 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
780 if (expanded != NULL)
782 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
783 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
784 return tls_error(string_sprintf(
785 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
789 if (cbinfo->privatekey != NULL &&
790 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
793 /* If expansion was forced to fail, key_expanded will be NULL. If the result
794 of the expansion is an empty string, ignore it also, and assume the private
795 key is in the same file as the certificate. */
797 if (expanded != NULL && *expanded != 0)
799 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
800 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
801 return tls_error(string_sprintf(
802 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
806 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
808 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
811 if (expanded != NULL && *expanded != 0)
813 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
814 if (cbinfo->u_ocsp.server.file_expanded &&
815 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
818 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
820 ocsp_load_response(sctx, cbinfo, expanded);
832 /*************************************************
833 * Callback to handle SNI *
834 *************************************************/
836 /* Called when acting as server during the TLS session setup if a Server Name
837 Indication extension was sent by the client.
839 API documentation is OpenSSL s_server.c implementation.
842 s SSL* of the current session
843 ad unknown (part of OpenSSL API) (unused)
844 arg Callback of "our" registered data
846 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
849 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
851 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
853 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
854 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
856 int old_pool = store_pool;
859 return SSL_TLSEXT_ERR_OK;
861 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
862 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
864 /* Make the extension value available for expansion */
865 store_pool = POOL_PERM;
866 tls_in.sni = string_copy(US servername);
867 store_pool = old_pool;
869 if (!reexpand_tls_files_for_sni)
870 return SSL_TLSEXT_ERR_OK;
872 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
873 not confident that memcpy wouldn't break some internal reference counting.
874 Especially since there's a references struct member, which would be off. */
876 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
878 ERR_error_string(ERR_get_error(), ssl_errstring);
879 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
880 return SSL_TLSEXT_ERR_NOACK;
883 /* Not sure how many of these are actually needed, since SSL object
884 already exists. Might even need this selfsame callback, for reneg? */
886 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
887 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
888 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
889 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
890 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
891 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
892 if (cbinfo->server_cipher_list)
893 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
895 if (cbinfo->u_ocsp.server.file)
897 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
898 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
902 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
903 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
905 /* do this after setup_certs, because this can require the certs for verifying
907 rc = tls_expand_session_files(server_sni, cbinfo);
908 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
910 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
911 return SSL_TLSEXT_ERR_NOACK;
913 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
914 SSL_set_SSL_CTX(s, server_sni);
916 return SSL_TLSEXT_ERR_OK;
918 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
925 /*************************************************
926 * Callback to handle OCSP Stapling *
927 *************************************************/
929 /* Called when acting as server during the TLS session setup if the client
930 requests OCSP information with a Certificate Status Request.
932 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
938 tls_server_stapling_cb(SSL *s, void *arg)
940 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
941 uschar *response_der;
942 int response_der_len;
945 debug_printf("Received TLS status request (OCSP stapling); %s response.",
946 cbinfo->u_ocsp.server.response ? "have" : "lack");
948 tls_in.ocsp = OCSP_NOT_RESP;
949 if (!cbinfo->u_ocsp.server.response)
950 return SSL_TLSEXT_ERR_NOACK;
953 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
955 if (response_der_len <= 0)
956 return SSL_TLSEXT_ERR_NOACK;
958 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
959 tls_in.ocsp = OCSP_VFIED;
960 return SSL_TLSEXT_ERR_OK;
965 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
967 BIO_printf(bp, "\t%s: ", str);
968 ASN1_GENERALIZEDTIME_print(bp, time);
973 tls_client_stapling_cb(SSL *s, void *arg)
975 tls_ext_ctx_cb * cbinfo = arg;
976 const unsigned char * p;
982 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
983 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
986 /* Expect this when we requested ocsp but got none */
987 if ( cbinfo->u_ocsp.client.verify_required
988 && log_extra_selector & LX_tls_cipher)
989 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
991 DEBUG(D_tls) debug_printf(" null\n");
992 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
995 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
997 tls_out.ocsp = OCSP_FAILED;
998 if (log_extra_selector & LX_tls_cipher)
999 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1001 DEBUG(D_tls) debug_printf(" parse error\n");
1005 if(!(bs = OCSP_response_get1_basic(rsp)))
1007 tls_out.ocsp = OCSP_FAILED;
1008 if (log_extra_selector & LX_tls_cipher)
1009 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1011 DEBUG(D_tls) debug_printf(" error parsing response\n");
1012 OCSP_RESPONSE_free(rsp);
1016 /* We'd check the nonce here if we'd put one in the request. */
1017 /* However that would defeat cacheability on the server so we don't. */
1019 /* This section of code reworked from OpenSSL apps source;
1020 The OpenSSL Project retains copyright:
1021 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1026 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1028 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1030 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1032 /* Use the chain that verified the server cert to verify the stapled info */
1033 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1035 if ((i = OCSP_basic_verify(bs, NULL,
1036 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1038 tls_out.ocsp = OCSP_FAILED;
1039 if (log_extra_selector & LX_tls_cipher)
1040 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1041 BIO_printf(bp, "OCSP response verify failure\n");
1042 ERR_print_errors(bp);
1043 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1047 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1050 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1051 OCSP_SINGLERESP * single;
1053 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1055 tls_out.ocsp = OCSP_FAILED;
1056 log_write(0, LOG_MAIN, "OCSP stapling "
1057 "with multiple responses not handled");
1058 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1061 single = OCSP_resp_get0(bs, 0);
1062 status = OCSP_single_get0_status(single, &reason, &rev,
1063 &thisupd, &nextupd);
1066 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1067 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1068 if (!OCSP_check_validity(thisupd, nextupd,
1069 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1071 tls_out.ocsp = OCSP_FAILED;
1072 DEBUG(D_tls) ERR_print_errors(bp);
1073 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1074 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1078 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1079 OCSP_cert_status_str(status));
1082 case V_OCSP_CERTSTATUS_GOOD:
1083 tls_out.ocsp = OCSP_VFIED;
1086 case V_OCSP_CERTSTATUS_REVOKED:
1087 tls_out.ocsp = OCSP_FAILED;
1088 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1089 reason != -1 ? "; reason: " : "",
1090 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1091 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1092 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1095 tls_out.ocsp = OCSP_FAILED;
1096 log_write(0, LOG_MAIN,
1097 "Server certificate status unknown, in OCSP stapling");
1098 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1106 OCSP_RESPONSE_free(rsp);
1109 #endif /*!DISABLE_OCSP*/
1112 /*************************************************
1113 * Initialize for TLS *
1114 *************************************************/
1116 /* Called from both server and client code, to do preliminary initialization
1117 of the library. We allocate and return a context structure.
1120 ctxp returned SSL context
1121 host connected host, if client; NULL if server
1122 dhparam DH parameter file
1123 certificate certificate file
1124 privatekey private key
1125 ocsp_file file of stapling info (server); flag for require ocsp (client)
1126 addr address if client; NULL if server (for some randomness)
1127 cbp place to put allocated callback context
1129 Returns: OK/DEFER/FAIL
1133 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1135 #ifndef DISABLE_OCSP
1138 address_item *addr, tls_ext_ctx_cb ** cbp)
1143 tls_ext_ctx_cb * cbinfo;
1145 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1146 cbinfo->certificate = certificate;
1147 cbinfo->privatekey = privatekey;
1148 #ifndef DISABLE_OCSP
1149 if ((cbinfo->is_server = host==NULL))
1151 cbinfo->u_ocsp.server.file = ocsp_file;
1152 cbinfo->u_ocsp.server.file_expanded = NULL;
1153 cbinfo->u_ocsp.server.response = NULL;
1156 cbinfo->u_ocsp.client.verify_store = NULL;
1158 cbinfo->dhparam = dhparam;
1159 cbinfo->server_cipher_list = NULL;
1160 cbinfo->host = host;
1161 #ifdef EXPERIMENTAL_EVENT
1162 cbinfo->event_action = NULL;
1165 SSL_load_error_strings(); /* basic set up */
1166 OpenSSL_add_ssl_algorithms();
1168 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1169 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1170 list of available digests. */
1171 EVP_add_digest(EVP_sha256());
1174 /* Create a context.
1175 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1176 negotiation in the different methods; as far as I can tell, the only
1177 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1178 when OpenSSL is built without SSLv2 support.
1179 By disabling with openssl_options, we can let admins re-enable with the
1182 *ctxp = SSL_CTX_new((host == NULL)?
1183 SSLv23_server_method() : SSLv23_client_method());
1185 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1187 /* It turns out that we need to seed the random number generator this early in
1188 order to get the full complement of ciphers to work. It took me roughly a day
1189 of work to discover this by experiment.
1191 On systems that have /dev/urandom, SSL may automatically seed itself from
1192 there. Otherwise, we have to make something up as best we can. Double check
1198 gettimeofday(&r.tv, NULL);
1201 RAND_seed((uschar *)(&r), sizeof(r));
1202 RAND_seed((uschar *)big_buffer, big_buffer_size);
1203 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1206 return tls_error(US"RAND_status", host,
1207 US"unable to seed random number generator");
1210 /* Set up the information callback, which outputs if debugging is at a suitable
1213 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1215 /* Automatically re-try reads/writes after renegotiation. */
1216 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1218 /* Apply administrator-supplied work-arounds.
1219 Historically we applied just one requested option,
1220 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1221 moved to an administrator-controlled list of options to specify and
1222 grandfathered in the first one as the default value for "openssl_options".
1224 No OpenSSL version number checks: the options we accept depend upon the
1225 availability of the option value macros from OpenSSL. */
1227 okay = tls_openssl_options_parse(openssl_options, &init_options);
1229 return tls_error(US"openssl_options parsing failed", host, NULL);
1233 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1234 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1235 return tls_error(string_sprintf(
1236 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1239 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1241 /* Initialize with DH parameters if supplied */
1243 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1245 /* Set up certificate and key (and perhaps OCSP info) */
1247 rc = tls_expand_session_files(*ctxp, cbinfo);
1248 if (rc != OK) return rc;
1250 /* If we need to handle SNI, do so */
1251 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1252 if (host == NULL) /* server */
1254 # ifndef DISABLE_OCSP
1255 /* We check u_ocsp.server.file, not server.response, because we care about if
1256 the option exists, not what the current expansion might be, as SNI might
1257 change the certificate and OCSP file in use between now and the time the
1258 callback is invoked. */
1259 if (cbinfo->u_ocsp.server.file)
1261 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1262 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1265 /* We always do this, so that $tls_sni is available even if not used in
1267 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1268 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1270 # ifndef DISABLE_OCSP
1272 if(ocsp_file) /* wanting stapling */
1274 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1276 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1279 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1280 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1285 cbinfo->verify_cert_hostnames = NULL;
1287 /* Set up the RSA callback */
1289 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1291 /* Finally, set the timeout, and we are done */
1293 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1294 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1304 /*************************************************
1305 * Get name of cipher in use *
1306 *************************************************/
1309 Argument: pointer to an SSL structure for the connection
1310 buffer to use for answer
1312 pointer to number of bits for cipher
1317 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1319 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1320 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1321 the accessor functions use const in the prototype. */
1322 const SSL_CIPHER *c;
1325 ver = (const uschar *)SSL_get_version(ssl);
1327 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1328 SSL_CIPHER_get_bits(c, bits);
1330 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1331 SSL_CIPHER_get_name(c), *bits);
1333 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1340 /*************************************************
1341 * Set up for verifying certificates *
1342 *************************************************/
1344 /* Called by both client and server startup
1347 sctx SSL_CTX* to initialise
1348 certs certs file or NULL
1349 crl CRL file or NULL
1350 host NULL in a server; the remote host in a client
1351 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1352 otherwise passed as FALSE
1353 cert_vfy_cb Callback function for certificate verification
1355 Returns: OK/DEFER/FAIL
1359 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1360 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1362 uschar *expcerts, *expcrl;
1364 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1367 if (expcerts != NULL && *expcerts != '\0')
1369 struct stat statbuf;
1370 if (!SSL_CTX_set_default_verify_paths(sctx))
1371 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1373 if (Ustat(expcerts, &statbuf) < 0)
1375 log_write(0, LOG_MAIN|LOG_PANIC,
1376 "failed to stat %s for certificates", expcerts);
1382 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1383 { file = NULL; dir = expcerts; }
1385 { file = expcerts; dir = NULL; }
1387 /* If a certificate file is empty, the next function fails with an
1388 unhelpful error message. If we skip it, we get the correct behaviour (no
1389 certificates are recognized, but the error message is still misleading (it
1390 says no certificate was supplied.) But this is better. */
1392 if ((file == NULL || statbuf.st_size > 0) &&
1393 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1394 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1396 /* Load the list of CAs for which we will accept certs, for sending
1397 to the client. This is only for the one-file tls_verify_certificates
1399 If a list isn't loaded into the server, but
1400 some verify locations are set, the server end appears to make
1401 a wildcard reqest for client certs.
1402 Meanwhile, the client library as deafult behaviour *ignores* the list
1403 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1404 Because of this, and that the dir variant is likely only used for
1405 the public-CA bundle (not for a private CA), not worth fixing.
1409 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1410 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1411 sk_X509_NAME_num(names));
1412 SSL_CTX_set_client_CA_list(sctx, names);
1416 /* Handle a certificate revocation list. */
1418 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1420 /* This bit of code is now the version supplied by Lars Mainka. (I have
1421 * merely reformatted it into the Exim code style.)
1423 * "From here I changed the code to add support for multiple crl's
1424 * in pem format in one file or to support hashed directory entries in
1425 * pem format instead of a file. This method now uses the library function
1426 * X509_STORE_load_locations to add the CRL location to the SSL context.
1427 * OpenSSL will then handle the verify against CA certs and CRLs by
1428 * itself in the verify callback." */
1430 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1431 if (expcrl != NULL && *expcrl != 0)
1433 struct stat statbufcrl;
1434 if (Ustat(expcrl, &statbufcrl) < 0)
1436 log_write(0, LOG_MAIN|LOG_PANIC,
1437 "failed to stat %s for certificates revocation lists", expcrl);
1442 /* is it a file or directory? */
1444 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1445 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1449 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1455 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1457 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1458 return tls_error(US"X509_STORE_load_locations", host, NULL);
1460 /* setting the flags to check against the complete crl chain */
1462 X509_STORE_set_flags(cvstore,
1463 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1467 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1469 /* If verification is optional, don't fail if no certificate */
1471 SSL_CTX_set_verify(sctx,
1472 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1481 /*************************************************
1482 * Start a TLS session in a server *
1483 *************************************************/
1485 /* This is called when Exim is running as a server, after having received
1486 the STARTTLS command. It must respond to that command, and then negotiate
1490 require_ciphers allowed ciphers
1492 Returns: OK on success
1493 DEFER for errors before the start of the negotiation
1494 FAIL for errors during the negotation; the server can't
1499 tls_server_start(const uschar *require_ciphers)
1503 tls_ext_ctx_cb *cbinfo;
1504 static uschar cipherbuf[256];
1506 /* Check for previous activation */
1508 if (tls_in.active >= 0)
1510 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1511 smtp_printf("554 Already in TLS\r\n");
1515 /* Initialize the SSL library. If it fails, it will already have logged
1518 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1519 #ifndef DISABLE_OCSP
1522 NULL, &server_static_cbinfo);
1523 if (rc != OK) return rc;
1524 cbinfo = server_static_cbinfo;
1526 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1529 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1530 were historically separated by underscores. So that I can use either form in my
1531 tests, and also for general convenience, we turn underscores into hyphens here.
1534 if (expciphers != NULL)
1536 uschar *s = expciphers;
1537 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1538 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1539 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1540 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1541 cbinfo->server_cipher_list = expciphers;
1544 /* If this is a host for which certificate verification is mandatory or
1545 optional, set up appropriately. */
1547 tls_in.certificate_verified = FALSE;
1548 #ifdef EXPERIMENTAL_DANE
1549 tls_in.dane_verified = FALSE;
1551 server_verify_callback_called = FALSE;
1553 if (verify_check_host(&tls_verify_hosts) == OK)
1555 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1556 FALSE, verify_callback_server);
1557 if (rc != OK) return rc;
1558 server_verify_optional = FALSE;
1560 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1562 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1563 TRUE, verify_callback_server);
1564 if (rc != OK) return rc;
1565 server_verify_optional = TRUE;
1568 /* Prepare for new connection */
1570 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1572 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1574 * With the SSL_clear(), we get strange interoperability bugs with
1575 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1576 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1578 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1579 * session shutdown. In this case, we have a brand new object and there's no
1580 * obvious reason to immediately clear it. I'm guessing that this was
1581 * originally added because of incomplete initialisation which the clear fixed,
1582 * in some historic release.
1585 /* Set context and tell client to go ahead, except in the case of TLS startup
1586 on connection, where outputting anything now upsets the clients and tends to
1587 make them disconnect. We need to have an explicit fflush() here, to force out
1588 the response. Other smtp_printf() calls do not need it, because in non-TLS
1589 mode, the fflush() happens when smtp_getc() is called. */
1591 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1592 if (!tls_in.on_connect)
1594 smtp_printf("220 TLS go ahead\r\n");
1598 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1599 that the OpenSSL library doesn't. */
1601 SSL_set_wfd(server_ssl, fileno(smtp_out));
1602 SSL_set_rfd(server_ssl, fileno(smtp_in));
1603 SSL_set_accept_state(server_ssl);
1605 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1607 sigalrm_seen = FALSE;
1608 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1609 rc = SSL_accept(server_ssl);
1614 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1615 if (ERR_get_error() == 0)
1616 log_write(0, LOG_MAIN,
1617 "TLS client disconnected cleanly (rejected our certificate?)");
1621 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1623 /* TLS has been set up. Adjust the input functions to read via TLS,
1624 and initialize things. */
1626 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1627 tls_in.cipher = cipherbuf;
1632 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1633 debug_printf("Shared ciphers: %s\n", buf);
1636 /* Record the certificate we presented */
1638 X509 * crt = SSL_get_certificate(server_ssl);
1639 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1642 /* Only used by the server-side tls (tls_in), including tls_getc.
1643 Client-side (tls_out) reads (seem to?) go via
1644 smtp_read_response()/ip_recv().
1645 Hence no need to duplicate for _in and _out.
1647 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1648 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1649 ssl_xfer_eof = ssl_xfer_error = 0;
1651 receive_getc = tls_getc;
1652 receive_ungetc = tls_ungetc;
1653 receive_feof = tls_feof;
1654 receive_ferror = tls_ferror;
1655 receive_smtp_buffered = tls_smtp_buffered;
1657 tls_in.active = fileno(smtp_out);
1665 tls_client_basic_ctx_init(SSL_CTX * ctx,
1666 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo
1670 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1671 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1672 the specified host patterns if one of them is defined */
1674 if ( (!ob->tls_verify_hosts && !ob->tls_try_verify_hosts)
1675 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
1677 client_verify_optional = FALSE;
1678 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
1679 client_verify_optional = TRUE;
1683 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1684 ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK)
1687 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
1689 cbinfo->verify_cert_hostnames = host->name;
1690 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1691 cbinfo->verify_cert_hostnames);
1697 #ifdef EXPERIMENTAL_DANE
1699 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1703 const char * hostnames[2] = { CS host->name, NULL };
1706 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1707 return tls_error(US"hostnames load", host, NULL);
1709 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1711 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1712 ) if (rr->type == T_TLSA)
1714 uschar * p = rr->data;
1715 uint8_t usage, selector, mtype;
1716 const char * mdname;
1720 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1721 if (usage != 2 && usage != 3) continue;
1728 default: continue; /* Only match-types 0, 1, 2 are supported */
1729 case 0: mdname = NULL; break;
1730 case 1: mdname = "sha256"; break;
1731 case 2: mdname = "sha512"; break;
1735 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1738 case 0: /* action not taken */
1739 return tls_error(US"tlsa load", host, NULL);
1743 tls_out.tlsa_usage |= 1<<usage;
1749 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1752 #endif /*EXPERIMENTAL_DANE*/
1756 /*************************************************
1757 * Start a TLS session in a client *
1758 *************************************************/
1760 /* Called from the smtp transport after STARTTLS has been accepted.
1763 fd the fd of the connection
1764 host connected host (for messages)
1765 addr the first address
1766 tb transport (always smtp)
1767 tlsa_dnsa tlsa lookup, if DANE, else null
1769 Returns: OK on success
1770 FAIL otherwise - note that tls_error() will not give DEFER
1771 because this is not a server
1775 tls_client_start(int fd, host_item *host, address_item *addr,
1776 transport_instance *tb
1777 #ifdef EXPERIMENTAL_DANE
1778 , dns_answer * tlsa_dnsa
1782 smtp_transport_options_block * ob =
1783 (smtp_transport_options_block *)tb->options_block;
1784 static uschar txt[256];
1785 uschar * expciphers;
1788 static uschar cipherbuf[256];
1790 #ifndef DISABLE_OCSP
1791 BOOL request_ocsp = FALSE;
1792 BOOL require_ocsp = FALSE;
1795 #ifdef EXPERIMENTAL_DANE
1796 tls_out.tlsa_usage = 0;
1799 #ifndef DISABLE_OCSP
1801 # ifdef EXPERIMENTAL_DANE
1803 && ob->hosts_request_ocsp[0] == '*'
1804 && ob->hosts_request_ocsp[1] == '\0'
1807 /* Unchanged from default. Use a safer one under DANE */
1808 request_ocsp = TRUE;
1809 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1810 " {= {4}{$tls_out_tlsa_usage}} } "
1816 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
1817 request_ocsp = TRUE;
1819 # ifdef EXPERIMENTAL_DANE
1823 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1827 rc = tls_init(&client_ctx, host, NULL,
1828 ob->tls_certificate, ob->tls_privatekey,
1829 #ifndef DISABLE_OCSP
1830 (void *)(long)request_ocsp,
1832 addr, &client_static_cbinfo);
1833 if (rc != OK) return rc;
1835 tls_out.certificate_verified = FALSE;
1836 client_verify_callback_called = FALSE;
1838 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1842 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1843 are separated by underscores. So that I can use either form in my tests, and
1844 also for general convenience, we turn underscores into hyphens here. */
1846 if (expciphers != NULL)
1848 uschar *s = expciphers;
1849 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1850 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1851 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1852 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1855 #ifdef EXPERIMENTAL_DANE
1858 SSL_CTX_set_verify(client_ctx,
1859 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1860 verify_callback_client_dane);
1862 if (!DANESSL_library_init())
1863 return tls_error(US"library init", host, NULL);
1864 if (DANESSL_CTX_init(client_ctx) <= 0)
1865 return tls_error(US"context init", host, NULL);
1871 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo))
1875 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1876 return tls_error(US"SSL_new", host, NULL);
1877 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1878 SSL_set_fd(client_ssl, fd);
1879 SSL_set_connect_state(client_ssl);
1883 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1885 if (tls_out.sni == NULL)
1887 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1889 else if (!Ustrlen(tls_out.sni))
1893 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1894 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1895 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1898 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1904 #ifdef EXPERIMENTAL_DANE
1906 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1910 #ifndef DISABLE_OCSP
1911 /* Request certificate status at connection-time. If the server
1912 does OCSP stapling we will get the callback (set in tls_init()) */
1913 # ifdef EXPERIMENTAL_DANE
1917 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1918 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1920 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1921 this means we avoid the OCSP request, we wasted the setup
1922 cost in tls_init(). */
1923 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
1924 request_ocsp = require_ocsp
1925 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1932 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1933 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1934 tls_out.ocsp = OCSP_NOT_RESP;
1938 #ifdef EXPERIMENTAL_EVENT
1939 client_static_cbinfo->event_action = tb->event_action;
1942 /* There doesn't seem to be a built-in timeout on connection. */
1944 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1945 sigalrm_seen = FALSE;
1946 alarm(ob->command_timeout);
1947 rc = SSL_connect(client_ssl);
1950 #ifdef EXPERIMENTAL_DANE
1952 DANESSL_cleanup(client_ssl);
1956 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1958 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1960 /* Beware anonymous ciphers which lead to server_cert being NULL */
1961 /*XXX server_cert is never freed... use X509_free() */
1962 server_cert = SSL_get_peer_certificate (client_ssl);
1965 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1966 CS txt, sizeof(txt));
1967 tls_out.peerdn = txt; /*XXX a static buffer... */
1970 tls_out.peerdn = NULL;
1972 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1973 tls_out.cipher = cipherbuf;
1975 /* Record the certificate we presented */
1977 X509 * crt = SSL_get_certificate(client_ssl);
1978 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1981 tls_out.active = fd;
1989 /*************************************************
1990 * TLS version of getc *
1991 *************************************************/
1993 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
1994 it refills the buffer via the SSL reading function.
1997 Returns: the next character or EOF
1999 Only used by the server-side TLS.
2005 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2010 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2011 ssl_xfer_buffer, ssl_xfer_buffer_size);
2013 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2014 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2015 error = SSL_get_error(server_ssl, inbytes);
2018 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2019 closed down, not that the socket itself has been closed down. Revert to
2020 non-SSL handling. */
2022 if (error == SSL_ERROR_ZERO_RETURN)
2024 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2026 receive_getc = smtp_getc;
2027 receive_ungetc = smtp_ungetc;
2028 receive_feof = smtp_feof;
2029 receive_ferror = smtp_ferror;
2030 receive_smtp_buffered = smtp_buffered;
2032 SSL_free(server_ssl);
2036 tls_in.cipher = NULL;
2037 tls_in.peerdn = NULL;
2043 /* Handle genuine errors */
2045 else if (error == SSL_ERROR_SSL)
2047 ERR_error_string(ERR_get_error(), ssl_errstring);
2048 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2053 else if (error != SSL_ERROR_NONE)
2055 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2060 #ifndef DISABLE_DKIM
2061 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2063 ssl_xfer_buffer_hwm = inbytes;
2064 ssl_xfer_buffer_lwm = 0;
2067 /* Something in the buffer; return next uschar */
2069 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2074 /*************************************************
2075 * Read bytes from TLS channel *
2076 *************************************************/
2083 Returns: the number of bytes read
2084 -1 after a failed read
2086 Only used by the client-side TLS.
2090 tls_read(BOOL is_server, uschar *buff, size_t len)
2092 SSL *ssl = is_server ? server_ssl : client_ssl;
2096 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2097 buff, (unsigned int)len);
2099 inbytes = SSL_read(ssl, CS buff, len);
2100 error = SSL_get_error(ssl, inbytes);
2102 if (error == SSL_ERROR_ZERO_RETURN)
2104 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2107 else if (error != SSL_ERROR_NONE)
2119 /*************************************************
2120 * Write bytes down TLS channel *
2121 *************************************************/
2125 is_server channel specifier
2129 Returns: the number of bytes after a successful write,
2130 -1 after a failed write
2132 Used by both server-side and client-side TLS.
2136 tls_write(BOOL is_server, const uschar *buff, size_t len)
2141 SSL *ssl = is_server ? server_ssl : client_ssl;
2143 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2146 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2147 outbytes = SSL_write(ssl, CS buff, left);
2148 error = SSL_get_error(ssl, outbytes);
2149 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2153 ERR_error_string(ERR_get_error(), ssl_errstring);
2154 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2157 case SSL_ERROR_NONE:
2162 case SSL_ERROR_ZERO_RETURN:
2163 log_write(0, LOG_MAIN, "SSL channel closed on write");
2166 case SSL_ERROR_SYSCALL:
2167 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2168 sender_fullhost ? sender_fullhost : US"<unknown>",
2172 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2181 /*************************************************
2182 * Close down a TLS session *
2183 *************************************************/
2185 /* This is also called from within a delivery subprocess forked from the
2186 daemon, to shut down the TLS library, without actually doing a shutdown (which
2187 would tamper with the SSL session in the parent process).
2189 Arguments: TRUE if SSL_shutdown is to be called
2192 Used by both server-side and client-side TLS.
2196 tls_close(BOOL is_server, BOOL shutdown)
2198 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2199 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2201 if (*fdp < 0) return; /* TLS was not active */
2205 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2206 SSL_shutdown(*sslp);
2218 /*************************************************
2219 * Let tls_require_ciphers be checked at startup *
2220 *************************************************/
2222 /* The tls_require_ciphers option, if set, must be something which the
2225 Returns: NULL on success, or error message
2229 tls_validate_require_cipher(void)
2232 uschar *s, *expciphers, *err;
2234 /* this duplicates from tls_init(), we need a better "init just global
2235 state, for no specific purpose" singleton function of our own */
2237 SSL_load_error_strings();
2238 OpenSSL_add_ssl_algorithms();
2239 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2240 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2241 list of available digests. */
2242 EVP_add_digest(EVP_sha256());
2245 if (!(tls_require_ciphers && *tls_require_ciphers))
2248 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2249 return US"failed to expand tls_require_ciphers";
2251 if (!(expciphers && *expciphers))
2254 /* normalisation ripped from above */
2256 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2260 ctx = SSL_CTX_new(SSLv23_server_method());
2263 ERR_error_string(ERR_get_error(), ssl_errstring);
2264 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2268 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2270 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2272 ERR_error_string(ERR_get_error(), ssl_errstring);
2273 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2284 /*************************************************
2285 * Report the library versions. *
2286 *************************************************/
2288 /* There have historically been some issues with binary compatibility in
2289 OpenSSL libraries; if Exim (like many other applications) is built against
2290 one version of OpenSSL but the run-time linker picks up another version,
2291 it can result in serious failures, including crashing with a SIGSEGV. So
2292 report the version found by the compiler and the run-time version.
2294 Note: some OS vendors backport security fixes without changing the version
2295 number/string, and the version date remains unchanged. The _build_ date
2296 will change, so we can more usefully assist with version diagnosis by also
2297 reporting the build date.
2299 Arguments: a FILE* to print the results to
2304 tls_version_report(FILE *f)
2306 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2309 OPENSSL_VERSION_TEXT,
2310 SSLeay_version(SSLEAY_VERSION),
2311 SSLeay_version(SSLEAY_BUILT_ON));
2312 /* third line is 38 characters for the %s and the line is 73 chars long;
2313 the OpenSSL output includes a "built on: " prefix already. */
2319 /*************************************************
2320 * Random number generation *
2321 *************************************************/
2323 /* Pseudo-random number generation. The result is not expected to be
2324 cryptographically strong but not so weak that someone will shoot themselves
2325 in the foot using it as a nonce in input in some email header scheme or
2326 whatever weirdness they'll twist this into. The result should handle fork()
2327 and avoid repeating sequences. OpenSSL handles that for us.
2331 Returns a random number in range [0, max-1]
2335 vaguely_random_number(int max)
2339 static pid_t pidlast = 0;
2342 uschar smallbuf[sizeof(r)];
2348 if (pidnow != pidlast)
2350 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2351 is unique for each thread", this doesn't apparently apply across processes,
2352 so our own warning from vaguely_random_number_fallback() applies here too.
2353 Fix per PostgreSQL. */
2359 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2363 gettimeofday(&r.tv, NULL);
2366 RAND_seed((uschar *)(&r), sizeof(r));
2368 /* We're after pseudo-random, not random; if we still don't have enough data
2369 in the internal PRNG then our options are limited. We could sleep and hope
2370 for entropy to come along (prayer technique) but if the system is so depleted
2371 in the first place then something is likely to just keep taking it. Instead,
2372 we'll just take whatever little bit of pseudo-random we can still manage to
2375 needed_len = sizeof(r);
2376 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2377 asked for a number less than 10. */
2378 for (r = max, i = 0; r; ++i)
2384 /* We do not care if crypto-strong */
2385 i = RAND_pseudo_bytes(smallbuf, needed_len);
2389 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2390 return vaguely_random_number_fallback(max);
2394 for (p = smallbuf; needed_len; --needed_len, ++p)
2400 /* We don't particularly care about weighted results; if someone wants
2401 smooth distribution and cares enough then they should submit a patch then. */
2408 /*************************************************
2409 * OpenSSL option parse *
2410 *************************************************/
2412 /* Parse one option for tls_openssl_options_parse below
2415 name one option name
2416 value place to store a value for it
2417 Returns success or failure in parsing
2420 struct exim_openssl_option {
2424 /* We could use a macro to expand, but we need the ifdef and not all the
2425 options document which version they were introduced in. Policylet: include
2426 all options unless explicitly for DTLS, let the administrator choose which
2429 This list is current as of:
2431 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2433 static struct exim_openssl_option exim_openssl_options[] = {
2434 /* KEEP SORTED ALPHABETICALLY! */
2436 { US"all", SSL_OP_ALL },
2438 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2439 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2441 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2442 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2444 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2445 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2447 #ifdef SSL_OP_EPHEMERAL_RSA
2448 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2450 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2451 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2453 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2454 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2456 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2457 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2459 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2460 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2462 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2463 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2465 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2466 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2468 #ifdef SSL_OP_NO_COMPRESSION
2469 { US"no_compression", SSL_OP_NO_COMPRESSION },
2471 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2472 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2474 #ifdef SSL_OP_NO_SSLv2
2475 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2477 #ifdef SSL_OP_NO_SSLv3
2478 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2480 #ifdef SSL_OP_NO_TICKET
2481 { US"no_ticket", SSL_OP_NO_TICKET },
2483 #ifdef SSL_OP_NO_TLSv1
2484 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2486 #ifdef SSL_OP_NO_TLSv1_1
2487 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2488 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2489 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2491 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2494 #ifdef SSL_OP_NO_TLSv1_2
2495 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2497 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2498 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2500 #ifdef SSL_OP_SINGLE_DH_USE
2501 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2503 #ifdef SSL_OP_SINGLE_ECDH_USE
2504 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2506 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2507 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2509 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2510 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2512 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2513 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2515 #ifdef SSL_OP_TLS_D5_BUG
2516 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2518 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2519 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2522 static int exim_openssl_options_size =
2523 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2527 tls_openssl_one_option_parse(uschar *name, long *value)
2530 int last = exim_openssl_options_size;
2531 while (last > first)
2533 int middle = (first + last)/2;
2534 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2537 *value = exim_openssl_options[middle].value;
2551 /*************************************************
2552 * OpenSSL option parsing logic *
2553 *************************************************/
2555 /* OpenSSL has a number of compatibility options which an administrator might
2556 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2557 we look like log_selector.
2560 option_spec the administrator-supplied string of options
2561 results ptr to long storage for the options bitmap
2562 Returns success or failure
2566 tls_openssl_options_parse(uschar *option_spec, long *results)
2571 BOOL adding, item_parsed;
2574 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2575 * from default because it increases BEAST susceptibility. */
2576 #ifdef SSL_OP_NO_SSLv2
2577 result |= SSL_OP_NO_SSLv2;
2580 if (option_spec == NULL)
2586 for (s=option_spec; *s != '\0'; /**/)
2588 while (isspace(*s)) ++s;
2591 if (*s != '+' && *s != '-')
2593 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2594 "+ or - expected but found \"%s\"\n", s);
2597 adding = *s++ == '+';
2598 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2601 item_parsed = tls_openssl_one_option_parse(s, &item);
2604 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2607 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2608 adding ? "adding" : "removing", result, item, s);
2623 /* End of tls-openssl.c */