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 const 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 name[sizeof(name)-1] = '\0';
249 debug_printf(" %s\n", name);
257 #ifdef EXPERIMENTAL_EVENT
259 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
260 BOOL *calledp, const BOOL *optionalp, const uschar * what)
266 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
269 old_cert = tlsp->peercert;
270 tlsp->peercert = X509_dup(cert);
271 /* NB we do not bother setting peerdn */
272 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
274 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
275 "depth=%d cert=%s: %s",
276 tlsp == &tls_out ? deliver_host_address : sender_host_address,
277 what, depth, dn, yield);
281 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
282 return 1; /* reject (leaving peercert set) */
284 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
285 "(host in tls_try_verify_hosts)\n");
287 X509_free(tlsp->peercert);
288 tlsp->peercert = old_cert;
294 /*************************************************
295 * Callback for verification *
296 *************************************************/
298 /* The SSL library does certificate verification if set up to do so. This
299 callback has the current yes/no state is in "state". If verification succeeded,
300 we set the certificate-verified flag. If verification failed, what happens
301 depends on whether the client is required to present a verifiable certificate
304 If verification is optional, we change the state to yes, but still log the
305 verification error. For some reason (it really would help to have proper
306 documentation of OpenSSL), this callback function then gets called again, this
307 time with state = 1. We must take care not to set the private verified flag on
308 the second time through.
310 Note: this function is not called if the client fails to present a certificate
311 when asked. We get here only if a certificate has been received. Handling of
312 optional verification for this case is done when requesting SSL to verify, by
313 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
315 May be called multiple times for different issues with a certificate, even
316 for a given "depth" in the certificate chain.
319 state current yes/no state as 1/0
320 x509ctx certificate information.
321 client TRUE for client startup, FALSE for server startup
323 Returns: 1 if verified, 0 if not
327 verify_callback(int state, X509_STORE_CTX *x509ctx,
328 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
330 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
331 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
334 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
335 dn[sizeof(dn)-1] = '\0';
339 log_write(0, LOG_MAIN, "[%s] SSL verify error: depth=%d error=%s cert=%s",
340 tlsp == &tls_out ? deliver_host_address : sender_host_address,
342 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
348 tlsp->peercert = X509_dup(cert); /* record failing cert */
349 return 0; /* reject */
351 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
352 "tls_try_verify_hosts)\n");
357 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
359 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
360 { /* client, wanting stapling */
361 /* Add the server cert's signing chain as the one
362 for the verification of the OCSP stapled information. */
364 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
369 #ifdef EXPERIMENTAL_EVENT
370 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
371 return 0; /* reject, with peercert set */
376 const uschar * verify_cert_hostnames;
378 if ( tlsp == &tls_out
379 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
380 /* client, wanting hostname check */
383 #if EXIM_HAVE_OPENSSL_CHECKHOST
384 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
385 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
387 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
388 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
391 const uschar * list = verify_cert_hostnames;
394 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
395 if ((rc = X509_check_host(cert, name, 0,
396 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
397 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS)))
401 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
402 tlsp == &tls_out ? deliver_host_address : sender_host_address);
409 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
412 log_write(0, LOG_MAIN,
413 "[%s] SSL verify error: certificate name mismatch: \"%s\"",
414 tlsp == &tls_out ? deliver_host_address : sender_host_address,
420 tlsp->peercert = X509_dup(cert); /* record failing cert */
421 return 0; /* reject */
423 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
424 "tls_try_verify_hosts)\n");
428 #ifdef EXPERIMENTAL_EVENT
429 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
430 return 0; /* reject, with peercert set */
433 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
434 *calledp ? "" : " authenticated", dn);
435 if (!*calledp) tlsp->certificate_verified = TRUE;
439 return 1; /* accept, at least for this level */
443 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
445 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
449 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
451 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
455 #ifdef EXPERIMENTAL_DANE
457 /* This gets called *by* the dane library verify callback, which interposes
461 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
463 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
465 #ifdef EXPERIMENTAL_EVENT
466 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
468 BOOL dummy_called, optional = FALSE;
471 X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn));
472 dn[sizeof(dn)-1] = '\0';
474 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", dn);
476 #ifdef EXPERIMENTAL_EVENT
477 if (verify_event(&tls_out, cert, depth, dn,
478 &dummy_called, &optional, US"DANE"))
479 return 0; /* reject, with peercert set */
483 tls_out.dane_verified =
484 tls_out.certificate_verified = TRUE;
488 #endif /*EXPERIMENTAL_DANE*/
491 /*************************************************
492 * Information callback *
493 *************************************************/
495 /* The SSL library functions call this from time to time to indicate what they
496 are doing. We copy the string to the debugging output when TLS debugging has
508 info_callback(SSL *s, int where, int ret)
512 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
517 /*************************************************
518 * Initialize for DH *
519 *************************************************/
521 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
524 dhparam DH parameter file or fixed parameter identity string
525 host connected host, if client; NULL if server
527 Returns: TRUE if OK (nothing to set up, or setup worked)
531 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host)
538 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
541 if (!dhexpanded || !*dhexpanded)
542 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
543 else if (dhexpanded[0] == '/')
545 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
547 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
548 host, US strerror(errno));
554 if (Ustrcmp(dhexpanded, "none") == 0)
556 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
560 if (!(pem = std_dh_prime_named(dhexpanded)))
562 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
563 host, US strerror(errno));
566 bio = BIO_new_mem_buf(CS pem, -1);
569 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
572 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
577 /* Even if it is larger, we silently return success rather than cause things
578 * to fail out, so that a too-large DH will not knock out all TLS; it's a
579 * debatable choice. */
580 if ((8*DH_size(dh)) > tls_dh_max_bits)
583 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
584 8*DH_size(dh), tls_dh_max_bits);
588 SSL_CTX_set_tmp_dh(sctx, dh);
590 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
591 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
604 /*************************************************
605 * Load OCSP information into state *
606 *************************************************/
608 /* Called to load the server OCSP response from the given file into memory, once
609 caller has determined this is needed. Checks validity. Debugs a message
612 ASSUMES: single response, for single cert.
615 sctx the SSL_CTX* to update
616 cbinfo various parts of session state
617 expanded the filename putatively holding an OCSP response
622 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
626 OCSP_BASICRESP *basic_response;
627 OCSP_SINGLERESP *single_response;
628 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
630 unsigned long verify_flags;
631 int status, reason, i;
633 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
634 if (cbinfo->u_ocsp.server.response)
636 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
637 cbinfo->u_ocsp.server.response = NULL;
640 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
643 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
644 cbinfo->u_ocsp.server.file_expanded);
648 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
652 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
656 status = OCSP_response_status(resp);
657 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
659 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
660 OCSP_response_status_str(status), status);
664 basic_response = OCSP_response_get1_basic(resp);
668 debug_printf("OCSP response parse error: unable to extract basic response.\n");
672 store = SSL_CTX_get_cert_store(sctx);
673 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
675 /* May need to expose ability to adjust those flags?
676 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
677 OCSP_TRUSTOTHER OCSP_NOINTERN */
679 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
683 ERR_error_string(ERR_get_error(), ssl_errstring);
684 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
689 /* Here's the simplifying assumption: there's only one response, for the
690 one certificate we use, and nothing for anything else in a chain. If this
691 proves false, we need to extract a cert id from our issued cert
692 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
693 right cert in the stack and then calls OCSP_single_get0_status()).
695 I'm hoping to avoid reworking a bunch more of how we handle state here. */
696 single_response = OCSP_resp_get0(basic_response, 0);
697 if (!single_response)
700 debug_printf("Unable to get first response from OCSP basic response.\n");
704 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
705 if (status != V_OCSP_CERTSTATUS_GOOD)
707 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
708 OCSP_cert_status_str(status), status,
709 OCSP_crl_reason_str(reason), reason);
713 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
715 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
720 cbinfo->u_ocsp.server.response = resp;
724 if (running_in_test_harness)
726 extern char ** environ;
728 for (p = USS environ; *p != NULL; p++)
729 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
731 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
732 goto supply_response;
737 #endif /*!DISABLE_OCSP*/
742 /*************************************************
743 * Expand key and cert file specs *
744 *************************************************/
746 /* Called once during tls_init and possibly again during TLS setup, for a
747 new context, if Server Name Indication was used and tls_sni was seen in
748 the certificate string.
751 sctx the SSL_CTX* to update
752 cbinfo various parts of session state
754 Returns: OK/DEFER/FAIL
758 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
762 if (cbinfo->certificate == NULL)
765 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
766 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
767 Ustrstr(cbinfo->certificate, US"tls_out_sni")
769 reexpand_tls_files_for_sni = TRUE;
771 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
774 if (expanded != NULL)
776 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
777 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
778 return tls_error(string_sprintf(
779 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
783 if (cbinfo->privatekey != NULL &&
784 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
787 /* If expansion was forced to fail, key_expanded will be NULL. If the result
788 of the expansion is an empty string, ignore it also, and assume the private
789 key is in the same file as the certificate. */
791 if (expanded != NULL && *expanded != 0)
793 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
794 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
795 return tls_error(string_sprintf(
796 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
800 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
802 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
805 if (expanded != NULL && *expanded != 0)
807 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
808 if (cbinfo->u_ocsp.server.file_expanded &&
809 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
812 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
814 ocsp_load_response(sctx, cbinfo, expanded);
826 /*************************************************
827 * Callback to handle SNI *
828 *************************************************/
830 /* Called when acting as server during the TLS session setup if a Server Name
831 Indication extension was sent by the client.
833 API documentation is OpenSSL s_server.c implementation.
836 s SSL* of the current session
837 ad unknown (part of OpenSSL API) (unused)
838 arg Callback of "our" registered data
840 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
843 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
845 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
847 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
848 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
850 int old_pool = store_pool;
853 return SSL_TLSEXT_ERR_OK;
855 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
856 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
858 /* Make the extension value available for expansion */
859 store_pool = POOL_PERM;
860 tls_in.sni = string_copy(US servername);
861 store_pool = old_pool;
863 if (!reexpand_tls_files_for_sni)
864 return SSL_TLSEXT_ERR_OK;
866 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
867 not confident that memcpy wouldn't break some internal reference counting.
868 Especially since there's a references struct member, which would be off. */
870 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
872 ERR_error_string(ERR_get_error(), ssl_errstring);
873 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
874 return SSL_TLSEXT_ERR_NOACK;
877 /* Not sure how many of these are actually needed, since SSL object
878 already exists. Might even need this selfsame callback, for reneg? */
880 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
881 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
882 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
883 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
884 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
885 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
886 if (cbinfo->server_cipher_list)
887 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
889 if (cbinfo->u_ocsp.server.file)
891 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
892 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
896 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
897 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
899 /* do this after setup_certs, because this can require the certs for verifying
901 rc = tls_expand_session_files(server_sni, cbinfo);
902 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
904 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
905 return SSL_TLSEXT_ERR_NOACK;
907 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
908 SSL_set_SSL_CTX(s, server_sni);
910 return SSL_TLSEXT_ERR_OK;
912 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
919 /*************************************************
920 * Callback to handle OCSP Stapling *
921 *************************************************/
923 /* Called when acting as server during the TLS session setup if the client
924 requests OCSP information with a Certificate Status Request.
926 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
932 tls_server_stapling_cb(SSL *s, void *arg)
934 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
935 uschar *response_der;
936 int response_der_len;
939 debug_printf("Received TLS status request (OCSP stapling); %s response.",
940 cbinfo->u_ocsp.server.response ? "have" : "lack");
942 tls_in.ocsp = OCSP_NOT_RESP;
943 if (!cbinfo->u_ocsp.server.response)
944 return SSL_TLSEXT_ERR_NOACK;
947 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
949 if (response_der_len <= 0)
950 return SSL_TLSEXT_ERR_NOACK;
952 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
953 tls_in.ocsp = OCSP_VFIED;
954 return SSL_TLSEXT_ERR_OK;
959 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
961 BIO_printf(bp, "\t%s: ", str);
962 ASN1_GENERALIZEDTIME_print(bp, time);
967 tls_client_stapling_cb(SSL *s, void *arg)
969 tls_ext_ctx_cb * cbinfo = arg;
970 const unsigned char * p;
976 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
977 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
980 /* Expect this when we requested ocsp but got none */
981 if ( cbinfo->u_ocsp.client.verify_required
982 && log_extra_selector & LX_tls_cipher)
983 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
985 DEBUG(D_tls) debug_printf(" null\n");
986 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
989 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
991 tls_out.ocsp = OCSP_FAILED;
992 if (log_extra_selector & LX_tls_cipher)
993 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
995 DEBUG(D_tls) debug_printf(" parse error\n");
999 if(!(bs = OCSP_response_get1_basic(rsp)))
1001 tls_out.ocsp = OCSP_FAILED;
1002 if (log_extra_selector & LX_tls_cipher)
1003 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1005 DEBUG(D_tls) debug_printf(" error parsing response\n");
1006 OCSP_RESPONSE_free(rsp);
1010 /* We'd check the nonce here if we'd put one in the request. */
1011 /* However that would defeat cacheability on the server so we don't. */
1013 /* This section of code reworked from OpenSSL apps source;
1014 The OpenSSL Project retains copyright:
1015 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1020 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1022 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1024 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1026 /* Use the chain that verified the server cert to verify the stapled info */
1027 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1029 if ((i = OCSP_basic_verify(bs, NULL,
1030 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1032 tls_out.ocsp = OCSP_FAILED;
1033 if (log_extra_selector & LX_tls_cipher)
1034 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1035 BIO_printf(bp, "OCSP response verify failure\n");
1036 ERR_print_errors(bp);
1037 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1041 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1044 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1045 OCSP_SINGLERESP * single;
1047 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1049 tls_out.ocsp = OCSP_FAILED;
1050 log_write(0, LOG_MAIN, "OCSP stapling "
1051 "with multiple responses not handled");
1052 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1055 single = OCSP_resp_get0(bs, 0);
1056 status = OCSP_single_get0_status(single, &reason, &rev,
1057 &thisupd, &nextupd);
1060 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1061 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1062 if (!OCSP_check_validity(thisupd, nextupd,
1063 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1065 tls_out.ocsp = OCSP_FAILED;
1066 DEBUG(D_tls) ERR_print_errors(bp);
1067 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1068 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1072 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1073 OCSP_cert_status_str(status));
1076 case V_OCSP_CERTSTATUS_GOOD:
1077 tls_out.ocsp = OCSP_VFIED;
1080 case V_OCSP_CERTSTATUS_REVOKED:
1081 tls_out.ocsp = OCSP_FAILED;
1082 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1083 reason != -1 ? "; reason: " : "",
1084 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1085 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1086 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1089 tls_out.ocsp = OCSP_FAILED;
1090 log_write(0, LOG_MAIN,
1091 "Server certificate status unknown, in OCSP stapling");
1092 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1100 OCSP_RESPONSE_free(rsp);
1103 #endif /*!DISABLE_OCSP*/
1106 /*************************************************
1107 * Initialize for TLS *
1108 *************************************************/
1110 /* Called from both server and client code, to do preliminary initialization
1111 of the library. We allocate and return a context structure.
1114 ctxp returned SSL context
1115 host connected host, if client; NULL if server
1116 dhparam DH parameter file
1117 certificate certificate file
1118 privatekey private key
1119 ocsp_file file of stapling info (server); flag for require ocsp (client)
1120 addr address if client; NULL if server (for some randomness)
1121 cbp place to put allocated callback context
1123 Returns: OK/DEFER/FAIL
1127 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1129 #ifndef DISABLE_OCSP
1132 address_item *addr, tls_ext_ctx_cb ** cbp)
1137 tls_ext_ctx_cb * cbinfo;
1139 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1140 cbinfo->certificate = certificate;
1141 cbinfo->privatekey = privatekey;
1142 #ifndef DISABLE_OCSP
1143 if ((cbinfo->is_server = host==NULL))
1145 cbinfo->u_ocsp.server.file = ocsp_file;
1146 cbinfo->u_ocsp.server.file_expanded = NULL;
1147 cbinfo->u_ocsp.server.response = NULL;
1150 cbinfo->u_ocsp.client.verify_store = NULL;
1152 cbinfo->dhparam = dhparam;
1153 cbinfo->server_cipher_list = NULL;
1154 cbinfo->host = host;
1155 #ifdef EXPERIMENTAL_EVENT
1156 cbinfo->event_action = NULL;
1159 SSL_load_error_strings(); /* basic set up */
1160 OpenSSL_add_ssl_algorithms();
1162 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1163 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1164 list of available digests. */
1165 EVP_add_digest(EVP_sha256());
1168 /* Create a context.
1169 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1170 negotiation in the different methods; as far as I can tell, the only
1171 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1172 when OpenSSL is built without SSLv2 support.
1173 By disabling with openssl_options, we can let admins re-enable with the
1176 *ctxp = SSL_CTX_new((host == NULL)?
1177 SSLv23_server_method() : SSLv23_client_method());
1179 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1181 /* It turns out that we need to seed the random number generator this early in
1182 order to get the full complement of ciphers to work. It took me roughly a day
1183 of work to discover this by experiment.
1185 On systems that have /dev/urandom, SSL may automatically seed itself from
1186 there. Otherwise, we have to make something up as best we can. Double check
1192 gettimeofday(&r.tv, NULL);
1195 RAND_seed((uschar *)(&r), sizeof(r));
1196 RAND_seed((uschar *)big_buffer, big_buffer_size);
1197 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1200 return tls_error(US"RAND_status", host,
1201 US"unable to seed random number generator");
1204 /* Set up the information callback, which outputs if debugging is at a suitable
1207 DEBUG(D_tls) SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1209 /* Automatically re-try reads/writes after renegotiation. */
1210 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1212 /* Apply administrator-supplied work-arounds.
1213 Historically we applied just one requested option,
1214 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1215 moved to an administrator-controlled list of options to specify and
1216 grandfathered in the first one as the default value for "openssl_options".
1218 No OpenSSL version number checks: the options we accept depend upon the
1219 availability of the option value macros from OpenSSL. */
1221 okay = tls_openssl_options_parse(openssl_options, &init_options);
1223 return tls_error(US"openssl_options parsing failed", host, NULL);
1227 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1228 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1229 return tls_error(string_sprintf(
1230 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1233 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1235 /* Initialize with DH parameters if supplied */
1237 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1239 /* Set up certificate and key (and perhaps OCSP info) */
1241 rc = tls_expand_session_files(*ctxp, cbinfo);
1242 if (rc != OK) return rc;
1244 /* If we need to handle SNI, do so */
1245 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1246 if (host == NULL) /* server */
1248 # ifndef DISABLE_OCSP
1249 /* We check u_ocsp.server.file, not server.response, because we care about if
1250 the option exists, not what the current expansion might be, as SNI might
1251 change the certificate and OCSP file in use between now and the time the
1252 callback is invoked. */
1253 if (cbinfo->u_ocsp.server.file)
1255 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1256 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1259 /* We always do this, so that $tls_sni is available even if not used in
1261 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1262 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1264 # ifndef DISABLE_OCSP
1266 if(ocsp_file) /* wanting stapling */
1268 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1270 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1273 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1274 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1279 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);
1332 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned bsize)
1334 /*XXX we might consider a list-of-certs variable for the cert chain.
1335 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
1336 in list-handling functions, also consider the difference between the entire
1337 chain and the elements sent by the peer. */
1339 /* Will have already noted peercert on a verify fail; possibly not the leaf */
1340 if (!tlsp->peercert)
1341 tlsp->peercert = SSL_get_peer_certificate(ssl);
1342 /* Beware anonymous ciphers which lead to server_cert being NULL */
1345 X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, bsize);
1346 peerdn[bsize-1] = '\0';
1347 tlsp->peerdn = peerdn; /*XXX a static buffer... */
1350 tlsp->peerdn = NULL;
1357 /*************************************************
1358 * Set up for verifying certificates *
1359 *************************************************/
1361 /* Called by both client and server startup
1364 sctx SSL_CTX* to initialise
1365 certs certs file or NULL
1366 crl CRL file or NULL
1367 host NULL in a server; the remote host in a client
1368 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1369 otherwise passed as FALSE
1370 cert_vfy_cb Callback function for certificate verification
1372 Returns: OK/DEFER/FAIL
1376 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1377 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1379 uschar *expcerts, *expcrl;
1381 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1384 if (expcerts != NULL && *expcerts != '\0')
1386 if (Ustrcmp(expcerts, "system") == 0)
1388 /* Tell the library to use its compiled-in location for the system default
1391 if (!SSL_CTX_set_default_verify_paths(sctx))
1392 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1396 struct stat statbuf;
1398 /* Tell the library to use its compiled-in location for the system default
1399 CA bundle. Those given by the exim config are additional to these */
1401 if (!SSL_CTX_set_default_verify_paths(sctx))
1402 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1404 if (Ustat(expcerts, &statbuf) < 0)
1406 log_write(0, LOG_MAIN|LOG_PANIC,
1407 "failed to stat %s for certificates", expcerts);
1413 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1414 { file = NULL; dir = expcerts; }
1416 { file = expcerts; dir = NULL; }
1418 /* If a certificate file is empty, the next function fails with an
1419 unhelpful error message. If we skip it, we get the correct behaviour (no
1420 certificates are recognized, but the error message is still misleading (it
1421 says no certificate was supplied.) But this is better. */
1423 if ((file == NULL || statbuf.st_size > 0) &&
1424 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1425 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1427 /* Load the list of CAs for which we will accept certs, for sending
1428 to the client. This is only for the one-file tls_verify_certificates
1430 If a list isn't loaded into the server, but
1431 some verify locations are set, the server end appears to make
1432 a wildcard reqest for client certs.
1433 Meanwhile, the client library as deafult behaviour *ignores* the list
1434 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1435 Because of this, and that the dir variant is likely only used for
1436 the public-CA bundle (not for a private CA), not worth fixing.
1440 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1441 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1442 sk_X509_NAME_num(names));
1443 SSL_CTX_set_client_CA_list(sctx, names);
1448 /* Handle a certificate revocation list. */
1450 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1452 /* This bit of code is now the version supplied by Lars Mainka. (I have
1453 * merely reformatted it into the Exim code style.)
1455 * "From here I changed the code to add support for multiple crl's
1456 * in pem format in one file or to support hashed directory entries in
1457 * pem format instead of a file. This method now uses the library function
1458 * X509_STORE_load_locations to add the CRL location to the SSL context.
1459 * OpenSSL will then handle the verify against CA certs and CRLs by
1460 * itself in the verify callback." */
1462 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1463 if (expcrl != NULL && *expcrl != 0)
1465 struct stat statbufcrl;
1466 if (Ustat(expcrl, &statbufcrl) < 0)
1468 log_write(0, LOG_MAIN|LOG_PANIC,
1469 "failed to stat %s for certificates revocation lists", expcrl);
1474 /* is it a file or directory? */
1476 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1477 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1481 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1487 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1489 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1490 return tls_error(US"X509_STORE_load_locations", host, NULL);
1492 /* setting the flags to check against the complete crl chain */
1494 X509_STORE_set_flags(cvstore,
1495 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1499 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1501 /* If verification is optional, don't fail if no certificate */
1503 SSL_CTX_set_verify(sctx,
1504 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1513 /*************************************************
1514 * Start a TLS session in a server *
1515 *************************************************/
1517 /* This is called when Exim is running as a server, after having received
1518 the STARTTLS command. It must respond to that command, and then negotiate
1522 require_ciphers allowed ciphers
1524 Returns: OK on success
1525 DEFER for errors before the start of the negotiation
1526 FAIL for errors during the negotation; the server can't
1531 tls_server_start(const uschar *require_ciphers)
1535 tls_ext_ctx_cb *cbinfo;
1537 static uschar peerdn[256];
1538 static uschar cipherbuf[256];
1540 /* Check for previous activation */
1542 if (tls_in.active >= 0)
1544 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1545 smtp_printf("554 Already in TLS\r\n");
1549 /* Initialize the SSL library. If it fails, it will already have logged
1552 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1553 #ifndef DISABLE_OCSP
1556 NULL, &server_static_cbinfo);
1557 if (rc != OK) return rc;
1558 cbinfo = server_static_cbinfo;
1560 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1563 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1564 were historically separated by underscores. So that I can use either form in my
1565 tests, and also for general convenience, we turn underscores into hyphens here.
1568 if (expciphers != NULL)
1570 uschar *s = expciphers;
1571 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1572 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1573 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1574 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1575 cbinfo->server_cipher_list = expciphers;
1578 /* If this is a host for which certificate verification is mandatory or
1579 optional, set up appropriately. */
1581 tls_in.certificate_verified = FALSE;
1582 #ifdef EXPERIMENTAL_DANE
1583 tls_in.dane_verified = FALSE;
1585 server_verify_callback_called = FALSE;
1587 if (verify_check_host(&tls_verify_hosts) == OK)
1589 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1590 FALSE, verify_callback_server);
1591 if (rc != OK) return rc;
1592 server_verify_optional = FALSE;
1594 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1596 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1597 TRUE, verify_callback_server);
1598 if (rc != OK) return rc;
1599 server_verify_optional = TRUE;
1602 /* Prepare for new connection */
1604 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1606 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1608 * With the SSL_clear(), we get strange interoperability bugs with
1609 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1610 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1612 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1613 * session shutdown. In this case, we have a brand new object and there's no
1614 * obvious reason to immediately clear it. I'm guessing that this was
1615 * originally added because of incomplete initialisation which the clear fixed,
1616 * in some historic release.
1619 /* Set context and tell client to go ahead, except in the case of TLS startup
1620 on connection, where outputting anything now upsets the clients and tends to
1621 make them disconnect. We need to have an explicit fflush() here, to force out
1622 the response. Other smtp_printf() calls do not need it, because in non-TLS
1623 mode, the fflush() happens when smtp_getc() is called. */
1625 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1626 if (!tls_in.on_connect)
1628 smtp_printf("220 TLS go ahead\r\n");
1632 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1633 that the OpenSSL library doesn't. */
1635 SSL_set_wfd(server_ssl, fileno(smtp_out));
1636 SSL_set_rfd(server_ssl, fileno(smtp_in));
1637 SSL_set_accept_state(server_ssl);
1639 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1641 sigalrm_seen = FALSE;
1642 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1643 rc = SSL_accept(server_ssl);
1648 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1649 if (ERR_get_error() == 0)
1650 log_write(0, LOG_MAIN,
1651 "TLS client disconnected cleanly (rejected our certificate?)");
1655 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1657 /* TLS has been set up. Adjust the input functions to read via TLS,
1658 and initialize things. */
1660 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
1662 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1663 tls_in.cipher = cipherbuf;
1668 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1669 debug_printf("Shared ciphers: %s\n", buf);
1672 /* Record the certificate we presented */
1674 X509 * crt = SSL_get_certificate(server_ssl);
1675 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1678 /* Only used by the server-side tls (tls_in), including tls_getc.
1679 Client-side (tls_out) reads (seem to?) go via
1680 smtp_read_response()/ip_recv().
1681 Hence no need to duplicate for _in and _out.
1683 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1684 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1685 ssl_xfer_eof = ssl_xfer_error = 0;
1687 receive_getc = tls_getc;
1688 receive_ungetc = tls_ungetc;
1689 receive_feof = tls_feof;
1690 receive_ferror = tls_ferror;
1691 receive_smtp_buffered = tls_smtp_buffered;
1693 tls_in.active = fileno(smtp_out);
1701 tls_client_basic_ctx_init(SSL_CTX * ctx,
1702 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo
1706 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1707 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1708 the specified host patterns if one of them is defined */
1710 if ( ( !ob->tls_verify_hosts
1711 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
1713 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
1715 client_verify_optional = FALSE;
1716 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
1717 client_verify_optional = TRUE;
1721 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1722 ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK)
1725 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
1727 cbinfo->verify_cert_hostnames = host->name;
1728 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1729 cbinfo->verify_cert_hostnames);
1735 #ifdef EXPERIMENTAL_DANE
1737 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1741 const char * hostnames[2] = { CS host->name, NULL };
1744 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1745 return tls_error(US"hostnames load", host, NULL);
1747 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1749 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1750 ) if (rr->type == T_TLSA)
1752 uschar * p = rr->data;
1753 uint8_t usage, selector, mtype;
1754 const char * mdname;
1758 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1759 if (usage != 2 && usage != 3) continue;
1766 default: continue; /* Only match-types 0, 1, 2 are supported */
1767 case 0: mdname = NULL; break;
1768 case 1: mdname = "sha256"; break;
1769 case 2: mdname = "sha512"; break;
1773 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1776 case 0: /* action not taken */
1777 return tls_error(US"tlsa load", host, NULL);
1781 tls_out.tlsa_usage |= 1<<usage;
1787 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1790 #endif /*EXPERIMENTAL_DANE*/
1794 /*************************************************
1795 * Start a TLS session in a client *
1796 *************************************************/
1798 /* Called from the smtp transport after STARTTLS has been accepted.
1801 fd the fd of the connection
1802 host connected host (for messages)
1803 addr the first address
1804 tb transport (always smtp)
1805 tlsa_dnsa tlsa lookup, if DANE, else null
1807 Returns: OK on success
1808 FAIL otherwise - note that tls_error() will not give DEFER
1809 because this is not a server
1813 tls_client_start(int fd, host_item *host, address_item *addr,
1814 transport_instance *tb
1815 #ifdef EXPERIMENTAL_DANE
1816 , dns_answer * tlsa_dnsa
1820 smtp_transport_options_block * ob =
1821 (smtp_transport_options_block *)tb->options_block;
1822 static uschar peerdn[256];
1823 uschar * expciphers;
1825 static uschar cipherbuf[256];
1827 #ifndef DISABLE_OCSP
1828 BOOL request_ocsp = FALSE;
1829 BOOL require_ocsp = FALSE;
1832 #ifdef EXPERIMENTAL_DANE
1833 tls_out.tlsa_usage = 0;
1836 #ifndef DISABLE_OCSP
1838 # ifdef EXPERIMENTAL_DANE
1840 && ob->hosts_request_ocsp[0] == '*'
1841 && ob->hosts_request_ocsp[1] == '\0'
1844 /* Unchanged from default. Use a safer one under DANE */
1845 request_ocsp = TRUE;
1846 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1847 " {= {4}{$tls_out_tlsa_usage}} } "
1853 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
1854 request_ocsp = TRUE;
1856 # ifdef EXPERIMENTAL_DANE
1860 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1864 rc = tls_init(&client_ctx, host, NULL,
1865 ob->tls_certificate, ob->tls_privatekey,
1866 #ifndef DISABLE_OCSP
1867 (void *)(long)request_ocsp,
1869 addr, &client_static_cbinfo);
1870 if (rc != OK) return rc;
1872 tls_out.certificate_verified = FALSE;
1873 client_verify_callback_called = FALSE;
1875 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1879 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1880 are separated by underscores. So that I can use either form in my tests, and
1881 also for general convenience, we turn underscores into hyphens here. */
1883 if (expciphers != NULL)
1885 uschar *s = expciphers;
1886 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1887 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1888 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1889 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1892 #ifdef EXPERIMENTAL_DANE
1895 SSL_CTX_set_verify(client_ctx,
1896 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1897 verify_callback_client_dane);
1899 if (!DANESSL_library_init())
1900 return tls_error(US"library init", host, NULL);
1901 if (DANESSL_CTX_init(client_ctx) <= 0)
1902 return tls_error(US"context init", host, NULL);
1908 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo))
1912 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1913 return tls_error(US"SSL_new", host, NULL);
1914 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1915 SSL_set_fd(client_ssl, fd);
1916 SSL_set_connect_state(client_ssl);
1920 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1922 if (tls_out.sni == NULL)
1924 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1926 else if (!Ustrlen(tls_out.sni))
1930 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1931 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1932 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1935 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1941 #ifdef EXPERIMENTAL_DANE
1943 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1947 #ifndef DISABLE_OCSP
1948 /* Request certificate status at connection-time. If the server
1949 does OCSP stapling we will get the callback (set in tls_init()) */
1950 # ifdef EXPERIMENTAL_DANE
1954 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1955 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1957 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1958 this means we avoid the OCSP request, we wasted the setup
1959 cost in tls_init(). */
1960 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
1961 request_ocsp = require_ocsp
1962 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1969 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1970 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1971 tls_out.ocsp = OCSP_NOT_RESP;
1975 #ifdef EXPERIMENTAL_EVENT
1976 client_static_cbinfo->event_action = tb->event_action;
1979 /* There doesn't seem to be a built-in timeout on connection. */
1981 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1982 sigalrm_seen = FALSE;
1983 alarm(ob->command_timeout);
1984 rc = SSL_connect(client_ssl);
1987 #ifdef EXPERIMENTAL_DANE
1989 DANESSL_cleanup(client_ssl);
1993 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1995 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1997 peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
1999 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2000 tls_out.cipher = cipherbuf;
2002 /* Record the certificate we presented */
2004 X509 * crt = SSL_get_certificate(client_ssl);
2005 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2008 tls_out.active = fd;
2016 /*************************************************
2017 * TLS version of getc *
2018 *************************************************/
2020 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2021 it refills the buffer via the SSL reading function.
2024 Returns: the next character or EOF
2026 Only used by the server-side TLS.
2032 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2037 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2038 ssl_xfer_buffer, ssl_xfer_buffer_size);
2040 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2041 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2042 error = SSL_get_error(server_ssl, inbytes);
2045 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2046 closed down, not that the socket itself has been closed down. Revert to
2047 non-SSL handling. */
2049 if (error == SSL_ERROR_ZERO_RETURN)
2051 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2053 receive_getc = smtp_getc;
2054 receive_ungetc = smtp_ungetc;
2055 receive_feof = smtp_feof;
2056 receive_ferror = smtp_ferror;
2057 receive_smtp_buffered = smtp_buffered;
2059 SSL_free(server_ssl);
2063 tls_in.cipher = NULL;
2064 tls_in.peerdn = NULL;
2070 /* Handle genuine errors */
2072 else if (error == SSL_ERROR_SSL)
2074 ERR_error_string(ERR_get_error(), ssl_errstring);
2075 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2080 else if (error != SSL_ERROR_NONE)
2082 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2087 #ifndef DISABLE_DKIM
2088 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2090 ssl_xfer_buffer_hwm = inbytes;
2091 ssl_xfer_buffer_lwm = 0;
2094 /* Something in the buffer; return next uschar */
2096 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2101 /*************************************************
2102 * Read bytes from TLS channel *
2103 *************************************************/
2110 Returns: the number of bytes read
2111 -1 after a failed read
2113 Only used by the client-side TLS.
2117 tls_read(BOOL is_server, uschar *buff, size_t len)
2119 SSL *ssl = is_server ? server_ssl : client_ssl;
2123 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2124 buff, (unsigned int)len);
2126 inbytes = SSL_read(ssl, CS buff, len);
2127 error = SSL_get_error(ssl, inbytes);
2129 if (error == SSL_ERROR_ZERO_RETURN)
2131 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2134 else if (error != SSL_ERROR_NONE)
2146 /*************************************************
2147 * Write bytes down TLS channel *
2148 *************************************************/
2152 is_server channel specifier
2156 Returns: the number of bytes after a successful write,
2157 -1 after a failed write
2159 Used by both server-side and client-side TLS.
2163 tls_write(BOOL is_server, const uschar *buff, size_t len)
2168 SSL *ssl = is_server ? server_ssl : client_ssl;
2170 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2173 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2174 outbytes = SSL_write(ssl, CS buff, left);
2175 error = SSL_get_error(ssl, outbytes);
2176 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2180 ERR_error_string(ERR_get_error(), ssl_errstring);
2181 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2184 case SSL_ERROR_NONE:
2189 case SSL_ERROR_ZERO_RETURN:
2190 log_write(0, LOG_MAIN, "SSL channel closed on write");
2193 case SSL_ERROR_SYSCALL:
2194 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2195 sender_fullhost ? sender_fullhost : US"<unknown>",
2199 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2208 /*************************************************
2209 * Close down a TLS session *
2210 *************************************************/
2212 /* This is also called from within a delivery subprocess forked from the
2213 daemon, to shut down the TLS library, without actually doing a shutdown (which
2214 would tamper with the SSL session in the parent process).
2216 Arguments: TRUE if SSL_shutdown is to be called
2219 Used by both server-side and client-side TLS.
2223 tls_close(BOOL is_server, BOOL shutdown)
2225 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2226 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2228 if (*fdp < 0) return; /* TLS was not active */
2232 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2233 SSL_shutdown(*sslp);
2245 /*************************************************
2246 * Let tls_require_ciphers be checked at startup *
2247 *************************************************/
2249 /* The tls_require_ciphers option, if set, must be something which the
2252 Returns: NULL on success, or error message
2256 tls_validate_require_cipher(void)
2259 uschar *s, *expciphers, *err;
2261 /* this duplicates from tls_init(), we need a better "init just global
2262 state, for no specific purpose" singleton function of our own */
2264 SSL_load_error_strings();
2265 OpenSSL_add_ssl_algorithms();
2266 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2267 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2268 list of available digests. */
2269 EVP_add_digest(EVP_sha256());
2272 if (!(tls_require_ciphers && *tls_require_ciphers))
2275 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2276 return US"failed to expand tls_require_ciphers";
2278 if (!(expciphers && *expciphers))
2281 /* normalisation ripped from above */
2283 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2287 ctx = SSL_CTX_new(SSLv23_server_method());
2290 ERR_error_string(ERR_get_error(), ssl_errstring);
2291 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2295 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2297 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2299 ERR_error_string(ERR_get_error(), ssl_errstring);
2300 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2311 /*************************************************
2312 * Report the library versions. *
2313 *************************************************/
2315 /* There have historically been some issues with binary compatibility in
2316 OpenSSL libraries; if Exim (like many other applications) is built against
2317 one version of OpenSSL but the run-time linker picks up another version,
2318 it can result in serious failures, including crashing with a SIGSEGV. So
2319 report the version found by the compiler and the run-time version.
2321 Note: some OS vendors backport security fixes without changing the version
2322 number/string, and the version date remains unchanged. The _build_ date
2323 will change, so we can more usefully assist with version diagnosis by also
2324 reporting the build date.
2326 Arguments: a FILE* to print the results to
2331 tls_version_report(FILE *f)
2333 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2336 OPENSSL_VERSION_TEXT,
2337 SSLeay_version(SSLEAY_VERSION),
2338 SSLeay_version(SSLEAY_BUILT_ON));
2339 /* third line is 38 characters for the %s and the line is 73 chars long;
2340 the OpenSSL output includes a "built on: " prefix already. */
2346 /*************************************************
2347 * Random number generation *
2348 *************************************************/
2350 /* Pseudo-random number generation. The result is not expected to be
2351 cryptographically strong but not so weak that someone will shoot themselves
2352 in the foot using it as a nonce in input in some email header scheme or
2353 whatever weirdness they'll twist this into. The result should handle fork()
2354 and avoid repeating sequences. OpenSSL handles that for us.
2358 Returns a random number in range [0, max-1]
2362 vaguely_random_number(int max)
2366 static pid_t pidlast = 0;
2369 uschar smallbuf[sizeof(r)];
2375 if (pidnow != pidlast)
2377 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2378 is unique for each thread", this doesn't apparently apply across processes,
2379 so our own warning from vaguely_random_number_fallback() applies here too.
2380 Fix per PostgreSQL. */
2386 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2390 gettimeofday(&r.tv, NULL);
2393 RAND_seed((uschar *)(&r), sizeof(r));
2395 /* We're after pseudo-random, not random; if we still don't have enough data
2396 in the internal PRNG then our options are limited. We could sleep and hope
2397 for entropy to come along (prayer technique) but if the system is so depleted
2398 in the first place then something is likely to just keep taking it. Instead,
2399 we'll just take whatever little bit of pseudo-random we can still manage to
2402 needed_len = sizeof(r);
2403 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2404 asked for a number less than 10. */
2405 for (r = max, i = 0; r; ++i)
2411 /* We do not care if crypto-strong */
2412 i = RAND_pseudo_bytes(smallbuf, needed_len);
2416 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2417 return vaguely_random_number_fallback(max);
2421 for (p = smallbuf; needed_len; --needed_len, ++p)
2427 /* We don't particularly care about weighted results; if someone wants
2428 smooth distribution and cares enough then they should submit a patch then. */
2435 /*************************************************
2436 * OpenSSL option parse *
2437 *************************************************/
2439 /* Parse one option for tls_openssl_options_parse below
2442 name one option name
2443 value place to store a value for it
2444 Returns success or failure in parsing
2447 struct exim_openssl_option {
2451 /* We could use a macro to expand, but we need the ifdef and not all the
2452 options document which version they were introduced in. Policylet: include
2453 all options unless explicitly for DTLS, let the administrator choose which
2456 This list is current as of:
2458 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2460 static struct exim_openssl_option exim_openssl_options[] = {
2461 /* KEEP SORTED ALPHABETICALLY! */
2463 { US"all", SSL_OP_ALL },
2465 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2466 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2468 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2469 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2471 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2472 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2474 #ifdef SSL_OP_EPHEMERAL_RSA
2475 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2477 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2478 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2480 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2481 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2483 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2484 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2486 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2487 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2489 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2490 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2492 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2493 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2495 #ifdef SSL_OP_NO_COMPRESSION
2496 { US"no_compression", SSL_OP_NO_COMPRESSION },
2498 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2499 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2501 #ifdef SSL_OP_NO_SSLv2
2502 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2504 #ifdef SSL_OP_NO_SSLv3
2505 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2507 #ifdef SSL_OP_NO_TICKET
2508 { US"no_ticket", SSL_OP_NO_TICKET },
2510 #ifdef SSL_OP_NO_TLSv1
2511 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2513 #ifdef SSL_OP_NO_TLSv1_1
2514 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2515 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2516 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2518 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2521 #ifdef SSL_OP_NO_TLSv1_2
2522 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2524 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2525 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2527 #ifdef SSL_OP_SINGLE_DH_USE
2528 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2530 #ifdef SSL_OP_SINGLE_ECDH_USE
2531 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2533 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2534 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2536 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2537 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2539 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2540 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2542 #ifdef SSL_OP_TLS_D5_BUG
2543 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2545 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2546 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2549 static int exim_openssl_options_size =
2550 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2554 tls_openssl_one_option_parse(uschar *name, long *value)
2557 int last = exim_openssl_options_size;
2558 while (last > first)
2560 int middle = (first + last)/2;
2561 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2564 *value = exim_openssl_options[middle].value;
2578 /*************************************************
2579 * OpenSSL option parsing logic *
2580 *************************************************/
2582 /* OpenSSL has a number of compatibility options which an administrator might
2583 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2584 we look like log_selector.
2587 option_spec the administrator-supplied string of options
2588 results ptr to long storage for the options bitmap
2589 Returns success or failure
2593 tls_openssl_options_parse(uschar *option_spec, long *results)
2598 BOOL adding, item_parsed;
2601 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2602 * from default because it increases BEAST susceptibility. */
2603 #ifdef SSL_OP_NO_SSLv2
2604 result |= SSL_OP_NO_SSLv2;
2607 if (option_spec == NULL)
2613 for (s=option_spec; *s != '\0'; /**/)
2615 while (isspace(*s)) ++s;
2618 if (*s != '+' && *s != '-')
2620 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2621 "+ or - expected but found \"%s\"\n", s);
2624 adding = *s++ == '+';
2625 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2628 item_parsed = tls_openssl_one_option_parse(s, &item);
2631 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2634 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2635 adding ? "adding" : "removing", result, item, s);
2650 /* End of tls-openssl.c */