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: */
127 #ifdef EXPERIMENTAL_CERTNAMES
128 uschar * verify_cert_hostnames;
130 #ifdef EXPERIMENTAL_EVENT
131 uschar * event_action;
135 /* should figure out a cleanup of API to handle state preserved per
136 implementation, for various reasons, which can be void * in the APIs.
137 For now, we hack around it. */
138 tls_ext_ctx_cb *client_static_cbinfo = NULL;
139 tls_ext_ctx_cb *server_static_cbinfo = NULL;
142 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
143 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
146 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
147 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
150 static int tls_server_stapling_cb(SSL *s, void *arg);
154 /*************************************************
156 *************************************************/
158 /* Called from lots of places when errors occur before actually starting to do
159 the TLS handshake, that is, while the session is still in clear. Always returns
160 DEFER for a server and FAIL for a client so that most calls can use "return
161 tls_error(...)" to do this processing and then give an appropriate return. A
162 single function is used for both server and client, because it is called from
163 some shared functions.
166 prefix text to include in the logged error
167 host NULL if setting up a server;
168 the connected host if setting up a client
169 msg error message or NULL if we should ask OpenSSL
171 Returns: OK/DEFER/FAIL
175 tls_error(uschar *prefix, host_item *host, uschar *msg)
179 ERR_error_string(ERR_get_error(), ssl_errstring);
180 msg = (uschar *)ssl_errstring;
185 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
186 host->name, host->address, prefix, msg);
191 uschar *conn_info = smtp_get_connection_info();
192 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
194 /* I'd like to get separated H= here, but too hard for now */
195 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
196 conn_info, prefix, msg);
203 /*************************************************
204 * Callback to generate RSA key *
205 *************************************************/
213 Returns: pointer to generated key
217 rsa_callback(SSL *s, int export, int keylength)
220 export = export; /* Shut picky compilers up */
221 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
222 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
225 ERR_error_string(ERR_get_error(), ssl_errstring);
226 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
238 x509_store_dump_cert_s_names(X509_STORE * store)
240 STACK_OF(X509_OBJECT) * roots= store->objs;
242 static uschar name[256];
244 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
246 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
247 if(tmp_obj->type == X509_LU_X509)
249 X509 * current_cert= tmp_obj->data.x509;
250 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
251 debug_printf(" %s\n", name);
259 /*************************************************
260 * Callback for verification *
261 *************************************************/
263 /* The SSL library does certificate verification if set up to do so. This
264 callback has the current yes/no state is in "state". If verification succeeded,
265 we set up the tls_peerdn string. If verification failed, what happens depends
266 on whether the client is required to present a verifiable certificate or not.
268 If verification is optional, we change the state to yes, but still log the
269 verification error. For some reason (it really would help to have proper
270 documentation of OpenSSL), this callback function then gets called again, this
271 time with state = 1. In fact, that's useful, because we can set up the peerdn
272 value, but we must take care not to set the private verified flag on the second
275 Note: this function is not called if the client fails to present a certificate
276 when asked. We get here only if a certificate has been received. Handling of
277 optional verification for this case is done when requesting SSL to verify, by
278 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
280 May be called multiple times for different issues with a certificate, even
281 for a given "depth" in the certificate chain.
284 state current yes/no state as 1/0
285 x509ctx certificate information.
286 client TRUE for client startup, FALSE for server startup
288 Returns: 1 if verified, 0 if not
292 verify_callback(int state, X509_STORE_CTX *x509ctx,
293 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
295 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
296 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
298 static uschar txt[256];
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)),
308 tlsp->certificate_verified = FALSE;
312 tlsp->peercert = X509_dup(cert);
313 return 0; /* reject */
315 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
316 "tls_try_verify_hosts)\n");
321 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
323 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
324 { /* client, wanting stapling */
325 /* Add the server cert's signing chain as the one
326 for the verification of the OCSP stapled information. */
328 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
333 #ifdef EXPERIMENTAL_EVENT
334 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
337 tlsp->peercert = X509_dup(cert);
338 if (event_raise(ev, US"tls:cert", string_sprintf("%d", depth)) == DEFER)
340 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
341 "depth=%d cert=%s", depth, txt);
342 tlsp->certificate_verified = FALSE;
344 return 0; /* reject */
346 X509_free(tlsp->peercert);
347 tlsp->peercert = NULL;
353 #ifdef EXPERIMENTAL_CERTNAMES
354 uschar * verify_cert_hostnames;
358 tlsp->peercert = X509_dup(cert);
360 #ifdef EXPERIMENTAL_CERTNAMES
361 if ( tlsp == &tls_out
362 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
363 /* client, wanting hostname check */
365 # if EXIM_HAVE_OPENSSL_CHECKHOST
366 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
367 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
369 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
370 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
374 uschar * list = verify_cert_hostnames;
377 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
378 if ((rc = X509_check_host(cert, name, 0,
379 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
380 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS)))
384 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
391 log_write(0, LOG_MAIN,
392 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
393 return 0; /* reject */
397 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
399 log_write(0, LOG_MAIN,
400 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
401 return 0; /* reject */
404 #endif /*EXPERIMENTAL_CERTNAMES*/
406 #ifdef EXPERIMENTAL_EVENT
407 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
409 if (event_raise(ev, US"tls:cert", US"0") == DEFER)
411 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
412 "depth=0 cert=%s", txt);
413 tlsp->certificate_verified = FALSE;
415 return 0; /* reject */
419 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
420 *calledp ? "" : " authenticated", txt);
421 if (!*calledp) tlsp->certificate_verified = TRUE;
425 return 1; /* accept, at least for this level */
429 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
431 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
435 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
437 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
441 #ifdef EXPERIMENTAL_DANE
443 /* This gets called *by* the dane library verify callback, which interposes
447 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
449 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
450 static uschar txt[256];
451 #ifdef EXPERIMENTAL_EVENT
452 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
455 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
457 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
458 tls_out.peerdn = txt;
459 tls_out.peercert = X509_dup(cert);
461 #ifdef EXPERIMENTAL_EVENT
462 if (client_static_cbinfo->event_action)
464 if (event_raise(client_static_cbinfo->event_action,
465 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
467 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
468 "depth=%d cert=%s", depth, txt);
469 tls_out.certificate_verified = FALSE;
470 return 0; /* reject */
474 X509_free(tls_out.peercert);
475 tls_out.peercert = NULL;
481 tls_out.dane_verified =
482 tls_out.certificate_verified = TRUE;
486 #endif /*EXPERIMENTAL_DANE*/
489 /*************************************************
490 * Information callback *
491 *************************************************/
493 /* The SSL library functions call this from time to time to indicate what they
494 are doing. We copy the string to the debugging output when TLS debugging has
506 info_callback(SSL *s, int where, int ret)
510 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
515 /*************************************************
516 * Initialize for DH *
517 *************************************************/
519 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
522 dhparam DH parameter file or fixed parameter identity string
523 host connected host, if client; NULL if server
525 Returns: TRUE if OK (nothing to set up, or setup worked)
529 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
536 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
539 if (!dhexpanded || !*dhexpanded)
540 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
541 else if (dhexpanded[0] == '/')
543 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
545 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
546 host, US strerror(errno));
552 if (Ustrcmp(dhexpanded, "none") == 0)
554 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
558 if (!(pem = std_dh_prime_named(dhexpanded)))
560 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
561 host, US strerror(errno));
564 bio = BIO_new_mem_buf(CS pem, -1);
567 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
570 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
575 /* Even if it is larger, we silently return success rather than cause things
576 * to fail out, so that a too-large DH will not knock out all TLS; it's a
577 * debatable choice. */
578 if ((8*DH_size(dh)) > tls_dh_max_bits)
581 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
582 8*DH_size(dh), tls_dh_max_bits);
586 SSL_CTX_set_tmp_dh(sctx, dh);
588 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
589 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
602 /*************************************************
603 * Load OCSP information into state *
604 *************************************************/
606 /* Called to load the server OCSP response from the given file into memory, once
607 caller has determined this is needed. Checks validity. Debugs a message
610 ASSUMES: single response, for single cert.
613 sctx the SSL_CTX* to update
614 cbinfo various parts of session state
615 expanded the filename putatively holding an OCSP response
620 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
624 OCSP_BASICRESP *basic_response;
625 OCSP_SINGLERESP *single_response;
626 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
628 unsigned long verify_flags;
629 int status, reason, i;
631 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
632 if (cbinfo->u_ocsp.server.response)
634 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
635 cbinfo->u_ocsp.server.response = NULL;
638 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
641 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
642 cbinfo->u_ocsp.server.file_expanded);
646 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
650 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
654 status = OCSP_response_status(resp);
655 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
657 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
658 OCSP_response_status_str(status), status);
662 basic_response = OCSP_response_get1_basic(resp);
666 debug_printf("OCSP response parse error: unable to extract basic response.\n");
670 store = SSL_CTX_get_cert_store(sctx);
671 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
673 /* May need to expose ability to adjust those flags?
674 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
675 OCSP_TRUSTOTHER OCSP_NOINTERN */
677 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
681 ERR_error_string(ERR_get_error(), ssl_errstring);
682 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
687 /* Here's the simplifying assumption: there's only one response, for the
688 one certificate we use, and nothing for anything else in a chain. If this
689 proves false, we need to extract a cert id from our issued cert
690 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
691 right cert in the stack and then calls OCSP_single_get0_status()).
693 I'm hoping to avoid reworking a bunch more of how we handle state here. */
694 single_response = OCSP_resp_get0(basic_response, 0);
695 if (!single_response)
698 debug_printf("Unable to get first response from OCSP basic response.\n");
702 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
703 if (status != V_OCSP_CERTSTATUS_GOOD)
705 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
706 OCSP_cert_status_str(status), status,
707 OCSP_crl_reason_str(reason), reason);
711 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
713 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
718 cbinfo->u_ocsp.server.response = resp;
722 if (running_in_test_harness)
724 extern char ** environ;
726 for (p = USS environ; *p != NULL; p++)
727 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
729 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
730 goto supply_response;
735 #endif /*!DISABLE_OCSP*/
740 /*************************************************
741 * Expand key and cert file specs *
742 *************************************************/
744 /* Called once during tls_init and possibly again during TLS setup, for a
745 new context, if Server Name Indication was used and tls_sni was seen in
746 the certificate string.
749 sctx the SSL_CTX* to update
750 cbinfo various parts of session state
752 Returns: OK/DEFER/FAIL
756 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
760 if (cbinfo->certificate == NULL)
763 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
764 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
765 Ustrstr(cbinfo->certificate, US"tls_out_sni")
767 reexpand_tls_files_for_sni = TRUE;
769 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
772 if (expanded != NULL)
774 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
775 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
776 return tls_error(string_sprintf(
777 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
781 if (cbinfo->privatekey != NULL &&
782 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
785 /* If expansion was forced to fail, key_expanded will be NULL. If the result
786 of the expansion is an empty string, ignore it also, and assume the private
787 key is in the same file as the certificate. */
789 if (expanded != NULL && *expanded != 0)
791 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
792 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
793 return tls_error(string_sprintf(
794 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
798 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
800 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
803 if (expanded != NULL && *expanded != 0)
805 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
806 if (cbinfo->u_ocsp.server.file_expanded &&
807 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
810 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
812 ocsp_load_response(sctx, cbinfo, expanded);
824 /*************************************************
825 * Callback to handle SNI *
826 *************************************************/
828 /* Called when acting as server during the TLS session setup if a Server Name
829 Indication extension was sent by the client.
831 API documentation is OpenSSL s_server.c implementation.
834 s SSL* of the current session
835 ad unknown (part of OpenSSL API) (unused)
836 arg Callback of "our" registered data
838 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
841 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
843 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
845 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
846 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
848 int old_pool = store_pool;
851 return SSL_TLSEXT_ERR_OK;
853 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
854 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
856 /* Make the extension value available for expansion */
857 store_pool = POOL_PERM;
858 tls_in.sni = string_copy(US servername);
859 store_pool = old_pool;
861 if (!reexpand_tls_files_for_sni)
862 return SSL_TLSEXT_ERR_OK;
864 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
865 not confident that memcpy wouldn't break some internal reference counting.
866 Especially since there's a references struct member, which would be off. */
868 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
870 ERR_error_string(ERR_get_error(), ssl_errstring);
871 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
872 return SSL_TLSEXT_ERR_NOACK;
875 /* Not sure how many of these are actually needed, since SSL object
876 already exists. Might even need this selfsame callback, for reneg? */
878 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
879 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
880 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
881 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
882 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
883 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
884 if (cbinfo->server_cipher_list)
885 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
887 if (cbinfo->u_ocsp.server.file)
889 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
890 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
894 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
895 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
897 /* do this after setup_certs, because this can require the certs for verifying
899 rc = tls_expand_session_files(server_sni, cbinfo);
900 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
902 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
903 return SSL_TLSEXT_ERR_NOACK;
905 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
906 SSL_set_SSL_CTX(s, server_sni);
908 return SSL_TLSEXT_ERR_OK;
910 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
917 /*************************************************
918 * Callback to handle OCSP Stapling *
919 *************************************************/
921 /* Called when acting as server during the TLS session setup if the client
922 requests OCSP information with a Certificate Status Request.
924 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
930 tls_server_stapling_cb(SSL *s, void *arg)
932 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
933 uschar *response_der;
934 int response_der_len;
937 debug_printf("Received TLS status request (OCSP stapling); %s response.",
938 cbinfo->u_ocsp.server.response ? "have" : "lack");
940 tls_in.ocsp = OCSP_NOT_RESP;
941 if (!cbinfo->u_ocsp.server.response)
942 return SSL_TLSEXT_ERR_NOACK;
945 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
947 if (response_der_len <= 0)
948 return SSL_TLSEXT_ERR_NOACK;
950 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
951 tls_in.ocsp = OCSP_VFIED;
952 return SSL_TLSEXT_ERR_OK;
957 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
959 BIO_printf(bp, "\t%s: ", str);
960 ASN1_GENERALIZEDTIME_print(bp, time);
965 tls_client_stapling_cb(SSL *s, void *arg)
967 tls_ext_ctx_cb * cbinfo = arg;
968 const unsigned char * p;
974 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
975 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
978 /* Expect this when we requested ocsp but got none */
979 if ( cbinfo->u_ocsp.client.verify_required
980 && log_extra_selector & LX_tls_cipher)
981 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
983 DEBUG(D_tls) debug_printf(" null\n");
984 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
987 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
989 tls_out.ocsp = OCSP_FAILED;
990 if (log_extra_selector & LX_tls_cipher)
991 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
993 DEBUG(D_tls) debug_printf(" parse error\n");
997 if(!(bs = OCSP_response_get1_basic(rsp)))
999 tls_out.ocsp = OCSP_FAILED;
1000 if (log_extra_selector & LX_tls_cipher)
1001 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1003 DEBUG(D_tls) debug_printf(" error parsing response\n");
1004 OCSP_RESPONSE_free(rsp);
1008 /* We'd check the nonce here if we'd put one in the request. */
1009 /* However that would defeat cacheability on the server so we don't. */
1011 /* This section of code reworked from OpenSSL apps source;
1012 The OpenSSL Project retains copyright:
1013 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1018 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1020 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1022 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1024 /* Use the chain that verified the server cert to verify the stapled info */
1025 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1027 if ((i = OCSP_basic_verify(bs, NULL,
1028 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1030 tls_out.ocsp = OCSP_FAILED;
1031 if (log_extra_selector & LX_tls_cipher)
1032 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1033 BIO_printf(bp, "OCSP response verify failure\n");
1034 ERR_print_errors(bp);
1035 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1039 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1042 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1043 OCSP_SINGLERESP * single;
1045 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1047 tls_out.ocsp = OCSP_FAILED;
1048 log_write(0, LOG_MAIN, "OCSP stapling "
1049 "with multiple responses not handled");
1050 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1053 single = OCSP_resp_get0(bs, 0);
1054 status = OCSP_single_get0_status(single, &reason, &rev,
1055 &thisupd, &nextupd);
1058 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1059 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1060 if (!OCSP_check_validity(thisupd, nextupd,
1061 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1063 tls_out.ocsp = OCSP_FAILED;
1064 DEBUG(D_tls) ERR_print_errors(bp);
1065 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1066 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1070 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1071 OCSP_cert_status_str(status));
1074 case V_OCSP_CERTSTATUS_GOOD:
1075 tls_out.ocsp = OCSP_VFIED;
1078 case V_OCSP_CERTSTATUS_REVOKED:
1079 tls_out.ocsp = OCSP_FAILED;
1080 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1081 reason != -1 ? "; reason: " : "",
1082 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1083 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1084 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1087 tls_out.ocsp = OCSP_FAILED;
1088 log_write(0, LOG_MAIN,
1089 "Server certificate status unknown, in OCSP stapling");
1090 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1098 OCSP_RESPONSE_free(rsp);
1101 #endif /*!DISABLE_OCSP*/
1104 /*************************************************
1105 * Initialize for TLS *
1106 *************************************************/
1108 /* Called from both server and client code, to do preliminary initialization
1109 of the library. We allocate and return a context structure.
1112 ctxp returned SSL context
1113 host connected host, if client; NULL if server
1114 dhparam DH parameter file
1115 certificate certificate file
1116 privatekey private key
1117 ocsp_file file of stapling info (server); flag for require ocsp (client)
1118 addr address if client; NULL if server (for some randomness)
1119 cbp place to put allocated callback context
1121 Returns: OK/DEFER/FAIL
1125 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1127 #ifndef DISABLE_OCSP
1130 address_item *addr, tls_ext_ctx_cb ** cbp)
1135 tls_ext_ctx_cb * cbinfo;
1137 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1138 cbinfo->certificate = certificate;
1139 cbinfo->privatekey = privatekey;
1140 #ifndef DISABLE_OCSP
1141 if ((cbinfo->is_server = host==NULL))
1143 cbinfo->u_ocsp.server.file = ocsp_file;
1144 cbinfo->u_ocsp.server.file_expanded = NULL;
1145 cbinfo->u_ocsp.server.response = NULL;
1148 cbinfo->u_ocsp.client.verify_store = NULL;
1150 cbinfo->dhparam = dhparam;
1151 cbinfo->server_cipher_list = NULL;
1152 cbinfo->host = host;
1153 #ifdef EXPERIMENTAL_EVENT
1154 cbinfo->event_action = NULL;
1157 SSL_load_error_strings(); /* basic set up */
1158 OpenSSL_add_ssl_algorithms();
1160 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1161 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1162 list of available digests. */
1163 EVP_add_digest(EVP_sha256());
1166 /* Create a context.
1167 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1168 negotiation in the different methods; as far as I can tell, the only
1169 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1170 when OpenSSL is built without SSLv2 support.
1171 By disabling with openssl_options, we can let admins re-enable with the
1174 *ctxp = SSL_CTX_new((host == NULL)?
1175 SSLv23_server_method() : SSLv23_client_method());
1177 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1179 /* It turns out that we need to seed the random number generator this early in
1180 order to get the full complement of ciphers to work. It took me roughly a day
1181 of work to discover this by experiment.
1183 On systems that have /dev/urandom, SSL may automatically seed itself from
1184 there. Otherwise, we have to make something up as best we can. Double check
1190 gettimeofday(&r.tv, NULL);
1193 RAND_seed((uschar *)(&r), sizeof(r));
1194 RAND_seed((uschar *)big_buffer, big_buffer_size);
1195 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1198 return tls_error(US"RAND_status", host,
1199 US"unable to seed random number generator");
1202 /* Set up the information callback, which outputs if debugging is at a suitable
1205 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1207 /* Automatically re-try reads/writes after renegotiation. */
1208 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1210 /* Apply administrator-supplied work-arounds.
1211 Historically we applied just one requested option,
1212 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1213 moved to an administrator-controlled list of options to specify and
1214 grandfathered in the first one as the default value for "openssl_options".
1216 No OpenSSL version number checks: the options we accept depend upon the
1217 availability of the option value macros from OpenSSL. */
1219 okay = tls_openssl_options_parse(openssl_options, &init_options);
1221 return tls_error(US"openssl_options parsing failed", host, NULL);
1225 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1226 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1227 return tls_error(string_sprintf(
1228 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1231 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1233 /* Initialize with DH parameters if supplied */
1235 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1237 /* Set up certificate and key (and perhaps OCSP info) */
1239 rc = tls_expand_session_files(*ctxp, cbinfo);
1240 if (rc != OK) return rc;
1242 /* If we need to handle SNI, do so */
1243 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1244 if (host == NULL) /* server */
1246 # ifndef DISABLE_OCSP
1247 /* We check u_ocsp.server.file, not server.response, because we care about if
1248 the option exists, not what the current expansion might be, as SNI might
1249 change the certificate and OCSP file in use between now and the time the
1250 callback is invoked. */
1251 if (cbinfo->u_ocsp.server.file)
1253 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1254 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1257 /* We always do this, so that $tls_sni is available even if not used in
1259 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1260 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1262 # ifndef DISABLE_OCSP
1264 if(ocsp_file) /* wanting stapling */
1266 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1268 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1271 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1272 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1277 #ifdef EXPERIMENTAL_CERTNAMES
1278 cbinfo->verify_cert_hostnames = NULL;
1281 /* Set up the RSA callback */
1283 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1285 /* Finally, set the timeout, and we are done */
1287 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1288 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1298 /*************************************************
1299 * Get name of cipher in use *
1300 *************************************************/
1303 Argument: pointer to an SSL structure for the connection
1304 buffer to use for answer
1306 pointer to number of bits for cipher
1311 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1313 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1314 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1315 the accessor functions use const in the prototype. */
1316 const SSL_CIPHER *c;
1319 ver = (const uschar *)SSL_get_version(ssl);
1321 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1322 SSL_CIPHER_get_bits(c, bits);
1324 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1325 SSL_CIPHER_get_name(c), *bits);
1327 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1334 /*************************************************
1335 * Set up for verifying certificates *
1336 *************************************************/
1338 /* Called by both client and server startup
1341 sctx SSL_CTX* to initialise
1342 certs certs file or NULL
1343 crl CRL file or NULL
1344 host NULL in a server; the remote host in a client
1345 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1346 otherwise passed as FALSE
1347 cert_vfy_cb Callback function for certificate verification
1349 Returns: OK/DEFER/FAIL
1353 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1354 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1356 uschar *expcerts, *expcrl;
1358 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1361 if (expcerts != NULL && *expcerts != '\0')
1363 struct stat statbuf;
1364 if (!SSL_CTX_set_default_verify_paths(sctx))
1365 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1367 if (Ustat(expcerts, &statbuf) < 0)
1369 log_write(0, LOG_MAIN|LOG_PANIC,
1370 "failed to stat %s for certificates", expcerts);
1376 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1377 { file = NULL; dir = expcerts; }
1379 { file = expcerts; dir = NULL; }
1381 /* If a certificate file is empty, the next function fails with an
1382 unhelpful error message. If we skip it, we get the correct behaviour (no
1383 certificates are recognized, but the error message is still misleading (it
1384 says no certificate was supplied.) But this is better. */
1386 if ((file == NULL || statbuf.st_size > 0) &&
1387 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1388 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1390 /* Load the list of CAs for which we will accept certs, for sending
1391 to the client. This is only for the one-file tls_verify_certificates
1393 If a list isn't loaded into the server, but
1394 some verify locations are set, the server end appears to make
1395 a wildcard reqest for client certs.
1396 Meanwhile, the client library as deafult behaviour *ignores* the list
1397 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1398 Because of this, and that the dir variant is likely only used for
1399 the public-CA bundle (not for a private CA), not worth fixing.
1403 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1404 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1405 sk_X509_NAME_num(names));
1406 SSL_CTX_set_client_CA_list(sctx, names);
1410 /* Handle a certificate revocation list. */
1412 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1414 /* This bit of code is now the version supplied by Lars Mainka. (I have
1415 * merely reformatted it into the Exim code style.)
1417 * "From here I changed the code to add support for multiple crl's
1418 * in pem format in one file or to support hashed directory entries in
1419 * pem format instead of a file. This method now uses the library function
1420 * X509_STORE_load_locations to add the CRL location to the SSL context.
1421 * OpenSSL will then handle the verify against CA certs and CRLs by
1422 * itself in the verify callback." */
1424 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1425 if (expcrl != NULL && *expcrl != 0)
1427 struct stat statbufcrl;
1428 if (Ustat(expcrl, &statbufcrl) < 0)
1430 log_write(0, LOG_MAIN|LOG_PANIC,
1431 "failed to stat %s for certificates revocation lists", expcrl);
1436 /* is it a file or directory? */
1438 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1439 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1443 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1449 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1451 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1452 return tls_error(US"X509_STORE_load_locations", host, NULL);
1454 /* setting the flags to check against the complete crl chain */
1456 X509_STORE_set_flags(cvstore,
1457 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1461 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1463 /* If verification is optional, don't fail if no certificate */
1465 SSL_CTX_set_verify(sctx,
1466 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1475 /*************************************************
1476 * Start a TLS session in a server *
1477 *************************************************/
1479 /* This is called when Exim is running as a server, after having received
1480 the STARTTLS command. It must respond to that command, and then negotiate
1484 require_ciphers allowed ciphers
1486 Returns: OK on success
1487 DEFER for errors before the start of the negotiation
1488 FAIL for errors during the negotation; the server can't
1493 tls_server_start(const uschar *require_ciphers)
1497 tls_ext_ctx_cb *cbinfo;
1498 static uschar cipherbuf[256];
1500 /* Check for previous activation */
1502 if (tls_in.active >= 0)
1504 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1505 smtp_printf("554 Already in TLS\r\n");
1509 /* Initialize the SSL library. If it fails, it will already have logged
1512 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1513 #ifndef DISABLE_OCSP
1516 NULL, &server_static_cbinfo);
1517 if (rc != OK) return rc;
1518 cbinfo = server_static_cbinfo;
1520 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1523 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1524 were historically separated by underscores. So that I can use either form in my
1525 tests, and also for general convenience, we turn underscores into hyphens here.
1528 if (expciphers != NULL)
1530 uschar *s = expciphers;
1531 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1532 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1533 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1534 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1535 cbinfo->server_cipher_list = expciphers;
1538 /* If this is a host for which certificate verification is mandatory or
1539 optional, set up appropriately. */
1541 tls_in.certificate_verified = FALSE;
1542 #ifdef EXPERIMENTAL_DANE
1543 tls_in.dane_verified = FALSE;
1545 server_verify_callback_called = FALSE;
1547 if (verify_check_host(&tls_verify_hosts) == OK)
1549 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1550 FALSE, verify_callback_server);
1551 if (rc != OK) return rc;
1552 server_verify_optional = FALSE;
1554 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1556 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1557 TRUE, verify_callback_server);
1558 if (rc != OK) return rc;
1559 server_verify_optional = TRUE;
1562 /* Prepare for new connection */
1564 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1566 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1568 * With the SSL_clear(), we get strange interoperability bugs with
1569 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1570 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1572 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1573 * session shutdown. In this case, we have a brand new object and there's no
1574 * obvious reason to immediately clear it. I'm guessing that this was
1575 * originally added because of incomplete initialisation which the clear fixed,
1576 * in some historic release.
1579 /* Set context and tell client to go ahead, except in the case of TLS startup
1580 on connection, where outputting anything now upsets the clients and tends to
1581 make them disconnect. We need to have an explicit fflush() here, to force out
1582 the response. Other smtp_printf() calls do not need it, because in non-TLS
1583 mode, the fflush() happens when smtp_getc() is called. */
1585 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1586 if (!tls_in.on_connect)
1588 smtp_printf("220 TLS go ahead\r\n");
1592 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1593 that the OpenSSL library doesn't. */
1595 SSL_set_wfd(server_ssl, fileno(smtp_out));
1596 SSL_set_rfd(server_ssl, fileno(smtp_in));
1597 SSL_set_accept_state(server_ssl);
1599 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1601 sigalrm_seen = FALSE;
1602 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1603 rc = SSL_accept(server_ssl);
1608 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1609 if (ERR_get_error() == 0)
1610 log_write(0, LOG_MAIN,
1611 "TLS client disconnected cleanly (rejected our certificate?)");
1615 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1617 /* TLS has been set up. Adjust the input functions to read via TLS,
1618 and initialize things. */
1620 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1621 tls_in.cipher = cipherbuf;
1626 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1627 debug_printf("Shared ciphers: %s\n", buf);
1630 /* Record the certificate we presented */
1632 X509 * crt = SSL_get_certificate(server_ssl);
1633 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1636 /* Only used by the server-side tls (tls_in), including tls_getc.
1637 Client-side (tls_out) reads (seem to?) go via
1638 smtp_read_response()/ip_recv().
1639 Hence no need to duplicate for _in and _out.
1641 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1642 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1643 ssl_xfer_eof = ssl_xfer_error = 0;
1645 receive_getc = tls_getc;
1646 receive_ungetc = tls_ungetc;
1647 receive_feof = tls_feof;
1648 receive_ferror = tls_ferror;
1649 receive_smtp_buffered = tls_smtp_buffered;
1651 tls_in.active = fileno(smtp_out);
1659 tls_client_basic_ctx_init(SSL_CTX * ctx,
1660 host_item * host, smtp_transport_options_block * ob
1661 #ifdef EXPERIMENTAL_CERTNAMES
1662 , tls_ext_ctx_cb * cbinfo
1667 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1668 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1669 the specified host patterns if one of them is defined */
1671 if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1672 (verify_check_host(&ob->tls_verify_hosts) == OK))
1674 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1675 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1677 client_verify_optional = FALSE;
1679 #ifdef EXPERIMENTAL_CERTNAMES
1680 if (ob->tls_verify_cert_hostnames)
1682 if (!expand_check(ob->tls_verify_cert_hostnames,
1683 US"tls_verify_cert_hostnames",
1684 &cbinfo->verify_cert_hostnames))
1686 if (cbinfo->verify_cert_hostnames)
1687 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1688 cbinfo->verify_cert_hostnames);
1692 else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1694 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1695 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1697 client_verify_optional = TRUE;
1704 #ifdef EXPERIMENTAL_DANE
1706 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1710 const char * hostnames[2] = { CS host->name, NULL };
1713 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1714 return tls_error(US"hostnames load", host, NULL);
1716 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1718 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1719 ) if (rr->type == T_TLSA)
1721 uschar * p = rr->data;
1722 uint8_t usage, selector, mtype;
1723 const char * mdname;
1727 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1728 if (usage != 2 && usage != 3) continue;
1735 default: continue; /* Only match-types 0, 1, 2 are supported */
1736 case 0: mdname = NULL; break;
1737 case 1: mdname = "sha256"; break;
1738 case 2: mdname = "sha512"; break;
1742 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1745 case 0: /* action not taken */
1746 return tls_error(US"tlsa load", host, NULL);
1750 tls_out.tlsa_usage |= 1<<usage;
1756 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1759 #endif /*EXPERIMENTAL_DANE*/
1763 /*************************************************
1764 * Start a TLS session in a client *
1765 *************************************************/
1767 /* Called from the smtp transport after STARTTLS has been accepted.
1770 fd the fd of the connection
1771 host connected host (for messages)
1772 addr the first address
1773 tb transport (always smtp)
1774 tlsa_dnsa tlsa lookup, if DANE, else null
1776 Returns: OK on success
1777 FAIL otherwise - note that tls_error() will not give DEFER
1778 because this is not a server
1782 tls_client_start(int fd, host_item *host, address_item *addr,
1783 transport_instance *tb
1784 #ifdef EXPERIMENTAL_DANE
1785 , dns_answer * tlsa_dnsa
1789 smtp_transport_options_block * ob =
1790 (smtp_transport_options_block *)tb->options_block;
1791 static uschar txt[256];
1792 uschar * expciphers;
1795 static uschar cipherbuf[256];
1797 #ifndef DISABLE_OCSP
1798 BOOL request_ocsp = FALSE;
1799 BOOL require_ocsp = FALSE;
1802 #ifdef EXPERIMENTAL_DANE
1803 tls_out.tlsa_usage = 0;
1806 #ifndef DISABLE_OCSP
1808 # ifdef EXPERIMENTAL_DANE
1810 && ob->hosts_request_ocsp[0] == '*'
1811 && ob->hosts_request_ocsp[1] == '\0'
1814 /* Unchanged from default. Use a safer one under DANE */
1815 request_ocsp = TRUE;
1816 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1817 " {= {4}{$tls_out_tlsa_usage}} } "
1822 if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1823 NULL, host->name, host->address, NULL) == OK))
1824 request_ocsp = TRUE;
1826 # ifdef EXPERIMENTAL_DANE
1829 request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
1830 NULL, host->name, host->address, NULL) == OK;
1834 rc = tls_init(&client_ctx, host, NULL,
1835 ob->tls_certificate, ob->tls_privatekey,
1836 #ifndef DISABLE_OCSP
1837 (void *)(long)request_ocsp,
1839 addr, &client_static_cbinfo);
1840 if (rc != OK) return rc;
1842 tls_out.certificate_verified = FALSE;
1843 client_verify_callback_called = FALSE;
1845 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1849 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1850 are separated by underscores. So that I can use either form in my tests, and
1851 also for general convenience, we turn underscores into hyphens here. */
1853 if (expciphers != NULL)
1855 uschar *s = expciphers;
1856 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1857 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1858 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1859 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1862 #ifdef EXPERIMENTAL_DANE
1865 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1867 if (!DANESSL_library_init())
1868 return tls_error(US"library init", host, NULL);
1869 if (DANESSL_CTX_init(client_ctx) <= 0)
1870 return tls_error(US"context init", host, NULL);
1876 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
1877 #ifdef EXPERIMENTAL_CERTNAMES
1878 , client_static_cbinfo
1883 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1884 return tls_error(US"SSL_new", host, NULL);
1885 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1886 SSL_set_fd(client_ssl, fd);
1887 SSL_set_connect_state(client_ssl);
1891 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1893 if (tls_out.sni == NULL)
1895 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1897 else if (!Ustrlen(tls_out.sni))
1901 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1902 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1903 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1906 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1912 #ifdef EXPERIMENTAL_DANE
1914 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1918 #ifndef DISABLE_OCSP
1919 /* Request certificate status at connection-time. If the server
1920 does OCSP stapling we will get the callback (set in tls_init()) */
1921 # ifdef EXPERIMENTAL_DANE
1925 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1926 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1928 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1929 this means we avoid the OCSP request, we wasted the setup
1930 cost in tls_init(). */
1931 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1932 NULL, host->name, host->address, NULL) == OK;
1933 request_ocsp = require_ocsp ? TRUE
1934 : verify_check_this_host(&ob->hosts_request_ocsp,
1935 NULL, host->name, host->address, NULL) == OK;
1942 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1943 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1944 tls_out.ocsp = OCSP_NOT_RESP;
1948 #ifdef EXPERIMENTAL_EVENT
1949 client_static_cbinfo->event_action = tb->event_action;
1952 /* There doesn't seem to be a built-in timeout on connection. */
1954 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1955 sigalrm_seen = FALSE;
1956 alarm(ob->command_timeout);
1957 rc = SSL_connect(client_ssl);
1960 #ifdef EXPERIMENTAL_DANE
1962 DANESSL_cleanup(client_ssl);
1966 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1968 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1970 /* Beware anonymous ciphers which lead to server_cert being NULL */
1971 /*XXX server_cert is never freed... use X509_free() */
1972 server_cert = SSL_get_peer_certificate (client_ssl);
1975 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1976 CS txt, sizeof(txt));
1977 tls_out.peerdn = txt; /*XXX a static buffer... */
1980 tls_out.peerdn = NULL;
1982 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1983 tls_out.cipher = cipherbuf;
1985 /* Record the certificate we presented */
1987 X509 * crt = SSL_get_certificate(client_ssl);
1988 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1991 tls_out.active = fd;
1999 /*************************************************
2000 * TLS version of getc *
2001 *************************************************/
2003 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2004 it refills the buffer via the SSL reading function.
2007 Returns: the next character or EOF
2009 Only used by the server-side TLS.
2015 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2020 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2021 ssl_xfer_buffer, ssl_xfer_buffer_size);
2023 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2024 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2025 error = SSL_get_error(server_ssl, inbytes);
2028 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2029 closed down, not that the socket itself has been closed down. Revert to
2030 non-SSL handling. */
2032 if (error == SSL_ERROR_ZERO_RETURN)
2034 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2036 receive_getc = smtp_getc;
2037 receive_ungetc = smtp_ungetc;
2038 receive_feof = smtp_feof;
2039 receive_ferror = smtp_ferror;
2040 receive_smtp_buffered = smtp_buffered;
2042 SSL_free(server_ssl);
2046 tls_in.cipher = NULL;
2047 tls_in.peerdn = NULL;
2053 /* Handle genuine errors */
2055 else if (error == SSL_ERROR_SSL)
2057 ERR_error_string(ERR_get_error(), ssl_errstring);
2058 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2063 else if (error != SSL_ERROR_NONE)
2065 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2070 #ifndef DISABLE_DKIM
2071 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2073 ssl_xfer_buffer_hwm = inbytes;
2074 ssl_xfer_buffer_lwm = 0;
2077 /* Something in the buffer; return next uschar */
2079 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2084 /*************************************************
2085 * Read bytes from TLS channel *
2086 *************************************************/
2093 Returns: the number of bytes read
2094 -1 after a failed read
2096 Only used by the client-side TLS.
2100 tls_read(BOOL is_server, uschar *buff, size_t len)
2102 SSL *ssl = is_server ? server_ssl : client_ssl;
2106 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2107 buff, (unsigned int)len);
2109 inbytes = SSL_read(ssl, CS buff, len);
2110 error = SSL_get_error(ssl, inbytes);
2112 if (error == SSL_ERROR_ZERO_RETURN)
2114 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2117 else if (error != SSL_ERROR_NONE)
2129 /*************************************************
2130 * Write bytes down TLS channel *
2131 *************************************************/
2135 is_server channel specifier
2139 Returns: the number of bytes after a successful write,
2140 -1 after a failed write
2142 Used by both server-side and client-side TLS.
2146 tls_write(BOOL is_server, const uschar *buff, size_t len)
2151 SSL *ssl = is_server ? server_ssl : client_ssl;
2153 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2156 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2157 outbytes = SSL_write(ssl, CS buff, left);
2158 error = SSL_get_error(ssl, outbytes);
2159 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2163 ERR_error_string(ERR_get_error(), ssl_errstring);
2164 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2167 case SSL_ERROR_NONE:
2172 case SSL_ERROR_ZERO_RETURN:
2173 log_write(0, LOG_MAIN, "SSL channel closed on write");
2176 case SSL_ERROR_SYSCALL:
2177 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2178 sender_fullhost ? sender_fullhost : US"<unknown>",
2182 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2191 /*************************************************
2192 * Close down a TLS session *
2193 *************************************************/
2195 /* This is also called from within a delivery subprocess forked from the
2196 daemon, to shut down the TLS library, without actually doing a shutdown (which
2197 would tamper with the SSL session in the parent process).
2199 Arguments: TRUE if SSL_shutdown is to be called
2202 Used by both server-side and client-side TLS.
2206 tls_close(BOOL is_server, BOOL shutdown)
2208 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2209 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2211 if (*fdp < 0) return; /* TLS was not active */
2215 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2216 SSL_shutdown(*sslp);
2228 /*************************************************
2229 * Let tls_require_ciphers be checked at startup *
2230 *************************************************/
2232 /* The tls_require_ciphers option, if set, must be something which the
2235 Returns: NULL on success, or error message
2239 tls_validate_require_cipher(void)
2242 uschar *s, *expciphers, *err;
2244 /* this duplicates from tls_init(), we need a better "init just global
2245 state, for no specific purpose" singleton function of our own */
2247 SSL_load_error_strings();
2248 OpenSSL_add_ssl_algorithms();
2249 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2250 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2251 list of available digests. */
2252 EVP_add_digest(EVP_sha256());
2255 if (!(tls_require_ciphers && *tls_require_ciphers))
2258 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2259 return US"failed to expand tls_require_ciphers";
2261 if (!(expciphers && *expciphers))
2264 /* normalisation ripped from above */
2266 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2270 ctx = SSL_CTX_new(SSLv23_server_method());
2273 ERR_error_string(ERR_get_error(), ssl_errstring);
2274 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2278 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2280 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2282 ERR_error_string(ERR_get_error(), ssl_errstring);
2283 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2294 /*************************************************
2295 * Report the library versions. *
2296 *************************************************/
2298 /* There have historically been some issues with binary compatibility in
2299 OpenSSL libraries; if Exim (like many other applications) is built against
2300 one version of OpenSSL but the run-time linker picks up another version,
2301 it can result in serious failures, including crashing with a SIGSEGV. So
2302 report the version found by the compiler and the run-time version.
2304 Note: some OS vendors backport security fixes without changing the version
2305 number/string, and the version date remains unchanged. The _build_ date
2306 will change, so we can more usefully assist with version diagnosis by also
2307 reporting the build date.
2309 Arguments: a FILE* to print the results to
2314 tls_version_report(FILE *f)
2316 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2319 OPENSSL_VERSION_TEXT,
2320 SSLeay_version(SSLEAY_VERSION),
2321 SSLeay_version(SSLEAY_BUILT_ON));
2322 /* third line is 38 characters for the %s and the line is 73 chars long;
2323 the OpenSSL output includes a "built on: " prefix already. */
2329 /*************************************************
2330 * Random number generation *
2331 *************************************************/
2333 /* Pseudo-random number generation. The result is not expected to be
2334 cryptographically strong but not so weak that someone will shoot themselves
2335 in the foot using it as a nonce in input in some email header scheme or
2336 whatever weirdness they'll twist this into. The result should handle fork()
2337 and avoid repeating sequences. OpenSSL handles that for us.
2341 Returns a random number in range [0, max-1]
2345 vaguely_random_number(int max)
2349 static pid_t pidlast = 0;
2352 uschar smallbuf[sizeof(r)];
2358 if (pidnow != pidlast)
2360 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2361 is unique for each thread", this doesn't apparently apply across processes,
2362 so our own warning from vaguely_random_number_fallback() applies here too.
2363 Fix per PostgreSQL. */
2369 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2373 gettimeofday(&r.tv, NULL);
2376 RAND_seed((uschar *)(&r), sizeof(r));
2378 /* We're after pseudo-random, not random; if we still don't have enough data
2379 in the internal PRNG then our options are limited. We could sleep and hope
2380 for entropy to come along (prayer technique) but if the system is so depleted
2381 in the first place then something is likely to just keep taking it. Instead,
2382 we'll just take whatever little bit of pseudo-random we can still manage to
2385 needed_len = sizeof(r);
2386 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2387 asked for a number less than 10. */
2388 for (r = max, i = 0; r; ++i)
2394 /* We do not care if crypto-strong */
2395 i = RAND_pseudo_bytes(smallbuf, needed_len);
2399 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2400 return vaguely_random_number_fallback(max);
2404 for (p = smallbuf; needed_len; --needed_len, ++p)
2410 /* We don't particularly care about weighted results; if someone wants
2411 smooth distribution and cares enough then they should submit a patch then. */
2418 /*************************************************
2419 * OpenSSL option parse *
2420 *************************************************/
2422 /* Parse one option for tls_openssl_options_parse below
2425 name one option name
2426 value place to store a value for it
2427 Returns success or failure in parsing
2430 struct exim_openssl_option {
2434 /* We could use a macro to expand, but we need the ifdef and not all the
2435 options document which version they were introduced in. Policylet: include
2436 all options unless explicitly for DTLS, let the administrator choose which
2439 This list is current as of:
2441 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2443 static struct exim_openssl_option exim_openssl_options[] = {
2444 /* KEEP SORTED ALPHABETICALLY! */
2446 { US"all", SSL_OP_ALL },
2448 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2449 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2451 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2452 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2454 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2455 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2457 #ifdef SSL_OP_EPHEMERAL_RSA
2458 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2460 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2461 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2463 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2464 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2466 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2467 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2469 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2470 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2472 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2473 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2475 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2476 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2478 #ifdef SSL_OP_NO_COMPRESSION
2479 { US"no_compression", SSL_OP_NO_COMPRESSION },
2481 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2482 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2484 #ifdef SSL_OP_NO_SSLv2
2485 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2487 #ifdef SSL_OP_NO_SSLv3
2488 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2490 #ifdef SSL_OP_NO_TICKET
2491 { US"no_ticket", SSL_OP_NO_TICKET },
2493 #ifdef SSL_OP_NO_TLSv1
2494 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2496 #ifdef SSL_OP_NO_TLSv1_1
2497 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2498 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2499 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2501 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2504 #ifdef SSL_OP_NO_TLSv1_2
2505 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2507 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2508 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2510 #ifdef SSL_OP_SINGLE_DH_USE
2511 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2513 #ifdef SSL_OP_SINGLE_ECDH_USE
2514 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2516 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2517 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2519 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2520 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2522 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2523 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2525 #ifdef SSL_OP_TLS_D5_BUG
2526 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2528 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2529 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2532 static int exim_openssl_options_size =
2533 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2537 tls_openssl_one_option_parse(uschar *name, long *value)
2540 int last = exim_openssl_options_size;
2541 while (last > first)
2543 int middle = (first + last)/2;
2544 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2547 *value = exim_openssl_options[middle].value;
2561 /*************************************************
2562 * OpenSSL option parsing logic *
2563 *************************************************/
2565 /* OpenSSL has a number of compatibility options which an administrator might
2566 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2567 we look like log_selector.
2570 option_spec the administrator-supplied string of options
2571 results ptr to long storage for the options bitmap
2572 Returns success or failure
2576 tls_openssl_options_parse(uschar *option_spec, long *results)
2581 BOOL adding, item_parsed;
2584 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2585 * from default because it increases BEAST susceptibility. */
2586 #ifdef SSL_OP_NO_SSLv2
2587 result |= SSL_OP_NO_SSLv2;
2590 if (option_spec == NULL)
2596 for (s=option_spec; *s != '\0'; /**/)
2598 while (isspace(*s)) ++s;
2601 if (*s != '+' && *s != '-')
2603 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2604 "+ or - expected but found \"%s\"\n", s);
2607 adding = *s++ == '+';
2608 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2611 item_parsed = tls_openssl_one_option_parse(s, &item);
2614 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2617 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2618 adding ? "adding" : "removing", result, item, s);
2633 /* End of tls-openssl.c */