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 #ifdef 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,
402 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
403 tlsp == &tls_out ? deliver_host_address : sender_host_address);
410 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
413 log_write(0, LOG_MAIN,
414 "[%s] SSL verify error: certificate name mismatch: \"%s\"",
415 tlsp == &tls_out ? deliver_host_address : sender_host_address,
421 tlsp->peercert = X509_dup(cert); /* record failing cert */
422 return 0; /* reject */
424 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
425 "tls_try_verify_hosts)\n");
429 #ifdef EXPERIMENTAL_EVENT
430 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
431 return 0; /* reject, with peercert set */
434 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
435 *calledp ? "" : " authenticated", dn);
436 if (!*calledp) tlsp->certificate_verified = TRUE;
440 return 1; /* accept, at least for this level */
444 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
446 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
450 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
452 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
456 #ifdef EXPERIMENTAL_DANE
458 /* This gets called *by* the dane library verify callback, which interposes
462 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
464 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
466 #ifdef EXPERIMENTAL_EVENT
467 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;
1536 static uschar peerdn[256];
1537 static uschar cipherbuf[256];
1539 /* Check for previous activation */
1541 if (tls_in.active >= 0)
1543 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1544 smtp_printf("554 Already in TLS\r\n");
1548 /* Initialize the SSL library. If it fails, it will already have logged
1551 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1552 #ifndef DISABLE_OCSP
1555 NULL, &server_static_cbinfo);
1556 if (rc != OK) return rc;
1557 cbinfo = server_static_cbinfo;
1559 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1562 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1563 were historically separated by underscores. So that I can use either form in my
1564 tests, and also for general convenience, we turn underscores into hyphens here.
1567 if (expciphers != NULL)
1569 uschar *s = expciphers;
1570 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1571 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1572 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1573 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1574 cbinfo->server_cipher_list = expciphers;
1577 /* If this is a host for which certificate verification is mandatory or
1578 optional, set up appropriately. */
1580 tls_in.certificate_verified = FALSE;
1581 #ifdef EXPERIMENTAL_DANE
1582 tls_in.dane_verified = FALSE;
1584 server_verify_callback_called = FALSE;
1586 if (verify_check_host(&tls_verify_hosts) == OK)
1588 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1589 FALSE, verify_callback_server);
1590 if (rc != OK) return rc;
1591 server_verify_optional = FALSE;
1593 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1595 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1596 TRUE, verify_callback_server);
1597 if (rc != OK) return rc;
1598 server_verify_optional = TRUE;
1601 /* Prepare for new connection */
1603 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1605 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1607 * With the SSL_clear(), we get strange interoperability bugs with
1608 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1609 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1611 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1612 * session shutdown. In this case, we have a brand new object and there's no
1613 * obvious reason to immediately clear it. I'm guessing that this was
1614 * originally added because of incomplete initialisation which the clear fixed,
1615 * in some historic release.
1618 /* Set context and tell client to go ahead, except in the case of TLS startup
1619 on connection, where outputting anything now upsets the clients and tends to
1620 make them disconnect. We need to have an explicit fflush() here, to force out
1621 the response. Other smtp_printf() calls do not need it, because in non-TLS
1622 mode, the fflush() happens when smtp_getc() is called. */
1624 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1625 if (!tls_in.on_connect)
1627 smtp_printf("220 TLS go ahead\r\n");
1631 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1632 that the OpenSSL library doesn't. */
1634 SSL_set_wfd(server_ssl, fileno(smtp_out));
1635 SSL_set_rfd(server_ssl, fileno(smtp_in));
1636 SSL_set_accept_state(server_ssl);
1638 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1640 sigalrm_seen = FALSE;
1641 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1642 rc = SSL_accept(server_ssl);
1647 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1648 if (ERR_get_error() == 0)
1649 log_write(0, LOG_MAIN,
1650 "TLS client disconnected cleanly (rejected our certificate?)");
1654 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1656 /* TLS has been set up. Adjust the input functions to read via TLS,
1657 and initialize things. */
1659 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
1661 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1662 tls_in.cipher = cipherbuf;
1667 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1668 debug_printf("Shared ciphers: %s\n", buf);
1671 /* Record the certificate we presented */
1673 X509 * crt = SSL_get_certificate(server_ssl);
1674 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1677 /* Only used by the server-side tls (tls_in), including tls_getc.
1678 Client-side (tls_out) reads (seem to?) go via
1679 smtp_read_response()/ip_recv().
1680 Hence no need to duplicate for _in and _out.
1682 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1683 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1684 ssl_xfer_eof = ssl_xfer_error = 0;
1686 receive_getc = tls_getc;
1687 receive_ungetc = tls_ungetc;
1688 receive_feof = tls_feof;
1689 receive_ferror = tls_ferror;
1690 receive_smtp_buffered = tls_smtp_buffered;
1692 tls_in.active = fileno(smtp_out);
1700 tls_client_basic_ctx_init(SSL_CTX * ctx,
1701 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo
1705 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1706 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1707 the specified host patterns if one of them is defined */
1709 if ( ( !ob->tls_verify_hosts
1710 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
1712 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
1714 client_verify_optional = FALSE;
1715 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
1716 client_verify_optional = TRUE;
1720 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1721 ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK)
1724 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
1726 cbinfo->verify_cert_hostnames =
1727 #ifdef EXPERIMENTAL_INTERNATIONAL
1728 string_domain_utf8_to_alabel(host->name, NULL);
1732 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1733 cbinfo->verify_cert_hostnames);
1739 #ifdef EXPERIMENTAL_DANE
1741 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1745 const char * hostnames[2] = { CS host->name, NULL };
1748 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1749 return tls_error(US"hostnames load", host, NULL);
1751 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1753 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1754 ) if (rr->type == T_TLSA)
1756 uschar * p = rr->data;
1757 uint8_t usage, selector, mtype;
1758 const char * mdname;
1762 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1763 if (usage != 2 && usage != 3) continue;
1770 default: continue; /* Only match-types 0, 1, 2 are supported */
1771 case 0: mdname = NULL; break;
1772 case 1: mdname = "sha256"; break;
1773 case 2: mdname = "sha512"; break;
1777 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1780 case 0: /* action not taken */
1781 return tls_error(US"tlsa load", host, NULL);
1785 tls_out.tlsa_usage |= 1<<usage;
1791 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1794 #endif /*EXPERIMENTAL_DANE*/
1798 /*************************************************
1799 * Start a TLS session in a client *
1800 *************************************************/
1802 /* Called from the smtp transport after STARTTLS has been accepted.
1805 fd the fd of the connection
1806 host connected host (for messages)
1807 addr the first address
1808 tb transport (always smtp)
1809 tlsa_dnsa tlsa lookup, if DANE, else null
1811 Returns: OK on success
1812 FAIL otherwise - note that tls_error() will not give DEFER
1813 because this is not a server
1817 tls_client_start(int fd, host_item *host, address_item *addr,
1818 transport_instance *tb
1819 #ifdef EXPERIMENTAL_DANE
1820 , dns_answer * tlsa_dnsa
1824 smtp_transport_options_block * ob =
1825 (smtp_transport_options_block *)tb->options_block;
1826 static uschar peerdn[256];
1827 uschar * expciphers;
1829 static uschar cipherbuf[256];
1831 #ifndef DISABLE_OCSP
1832 BOOL request_ocsp = FALSE;
1833 BOOL require_ocsp = FALSE;
1836 #ifdef EXPERIMENTAL_DANE
1837 tls_out.tlsa_usage = 0;
1840 #ifndef DISABLE_OCSP
1842 # ifdef EXPERIMENTAL_DANE
1844 && ob->hosts_request_ocsp[0] == '*'
1845 && ob->hosts_request_ocsp[1] == '\0'
1848 /* Unchanged from default. Use a safer one under DANE */
1849 request_ocsp = TRUE;
1850 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1851 " {= {4}{$tls_out_tlsa_usage}} } "
1857 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
1858 request_ocsp = TRUE;
1860 # ifdef EXPERIMENTAL_DANE
1864 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1868 rc = tls_init(&client_ctx, host, NULL,
1869 ob->tls_certificate, ob->tls_privatekey,
1870 #ifndef DISABLE_OCSP
1871 (void *)(long)request_ocsp,
1873 addr, &client_static_cbinfo);
1874 if (rc != OK) return rc;
1876 tls_out.certificate_verified = FALSE;
1877 client_verify_callback_called = FALSE;
1879 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1883 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1884 are separated by underscores. So that I can use either form in my tests, and
1885 also for general convenience, we turn underscores into hyphens here. */
1887 if (expciphers != NULL)
1889 uschar *s = expciphers;
1890 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1891 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1892 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1893 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1896 #ifdef EXPERIMENTAL_DANE
1899 SSL_CTX_set_verify(client_ctx,
1900 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1901 verify_callback_client_dane);
1903 if (!DANESSL_library_init())
1904 return tls_error(US"library init", host, NULL);
1905 if (DANESSL_CTX_init(client_ctx) <= 0)
1906 return tls_error(US"context init", host, NULL);
1912 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo))
1916 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1917 return tls_error(US"SSL_new", host, NULL);
1918 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1919 SSL_set_fd(client_ssl, fd);
1920 SSL_set_connect_state(client_ssl);
1924 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1926 if (tls_out.sni == NULL)
1928 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1930 else if (!Ustrlen(tls_out.sni))
1934 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1935 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1936 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1939 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1945 #ifdef EXPERIMENTAL_DANE
1947 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1951 #ifndef DISABLE_OCSP
1952 /* Request certificate status at connection-time. If the server
1953 does OCSP stapling we will get the callback (set in tls_init()) */
1954 # ifdef EXPERIMENTAL_DANE
1958 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1959 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1961 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1962 this means we avoid the OCSP request, we wasted the setup
1963 cost in tls_init(). */
1964 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
1965 request_ocsp = require_ocsp
1966 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1973 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1974 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1975 tls_out.ocsp = OCSP_NOT_RESP;
1979 #ifdef EXPERIMENTAL_EVENT
1980 client_static_cbinfo->event_action = tb->event_action;
1983 /* There doesn't seem to be a built-in timeout on connection. */
1985 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1986 sigalrm_seen = FALSE;
1987 alarm(ob->command_timeout);
1988 rc = SSL_connect(client_ssl);
1991 #ifdef EXPERIMENTAL_DANE
1993 DANESSL_cleanup(client_ssl);
1997 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1999 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2001 peer_cert(client_ssl, &tls_out, peerdn, sizeof(peerdn));
2003 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2004 tls_out.cipher = cipherbuf;
2006 /* Record the certificate we presented */
2008 X509 * crt = SSL_get_certificate(client_ssl);
2009 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2012 tls_out.active = fd;
2020 /*************************************************
2021 * TLS version of getc *
2022 *************************************************/
2024 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2025 it refills the buffer via the SSL reading function.
2028 Returns: the next character or EOF
2030 Only used by the server-side TLS.
2036 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2041 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2042 ssl_xfer_buffer, ssl_xfer_buffer_size);
2044 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2045 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2046 error = SSL_get_error(server_ssl, inbytes);
2049 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2050 closed down, not that the socket itself has been closed down. Revert to
2051 non-SSL handling. */
2053 if (error == SSL_ERROR_ZERO_RETURN)
2055 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2057 receive_getc = smtp_getc;
2058 receive_ungetc = smtp_ungetc;
2059 receive_feof = smtp_feof;
2060 receive_ferror = smtp_ferror;
2061 receive_smtp_buffered = smtp_buffered;
2063 SSL_free(server_ssl);
2067 tls_in.cipher = NULL;
2068 tls_in.peerdn = NULL;
2074 /* Handle genuine errors */
2076 else if (error == SSL_ERROR_SSL)
2078 ERR_error_string(ERR_get_error(), ssl_errstring);
2079 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2084 else if (error != SSL_ERROR_NONE)
2086 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2091 #ifndef DISABLE_DKIM
2092 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2094 ssl_xfer_buffer_hwm = inbytes;
2095 ssl_xfer_buffer_lwm = 0;
2098 /* Something in the buffer; return next uschar */
2100 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2105 /*************************************************
2106 * Read bytes from TLS channel *
2107 *************************************************/
2114 Returns: the number of bytes read
2115 -1 after a failed read
2117 Only used by the client-side TLS.
2121 tls_read(BOOL is_server, uschar *buff, size_t len)
2123 SSL *ssl = is_server ? server_ssl : client_ssl;
2127 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2128 buff, (unsigned int)len);
2130 inbytes = SSL_read(ssl, CS buff, len);
2131 error = SSL_get_error(ssl, inbytes);
2133 if (error == SSL_ERROR_ZERO_RETURN)
2135 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2138 else if (error != SSL_ERROR_NONE)
2150 /*************************************************
2151 * Write bytes down TLS channel *
2152 *************************************************/
2156 is_server channel specifier
2160 Returns: the number of bytes after a successful write,
2161 -1 after a failed write
2163 Used by both server-side and client-side TLS.
2167 tls_write(BOOL is_server, const uschar *buff, size_t len)
2172 SSL *ssl = is_server ? server_ssl : client_ssl;
2174 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2177 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2178 outbytes = SSL_write(ssl, CS buff, left);
2179 error = SSL_get_error(ssl, outbytes);
2180 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2184 ERR_error_string(ERR_get_error(), ssl_errstring);
2185 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2188 case SSL_ERROR_NONE:
2193 case SSL_ERROR_ZERO_RETURN:
2194 log_write(0, LOG_MAIN, "SSL channel closed on write");
2197 case SSL_ERROR_SYSCALL:
2198 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2199 sender_fullhost ? sender_fullhost : US"<unknown>",
2203 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2212 /*************************************************
2213 * Close down a TLS session *
2214 *************************************************/
2216 /* This is also called from within a delivery subprocess forked from the
2217 daemon, to shut down the TLS library, without actually doing a shutdown (which
2218 would tamper with the SSL session in the parent process).
2220 Arguments: TRUE if SSL_shutdown is to be called
2223 Used by both server-side and client-side TLS.
2227 tls_close(BOOL is_server, BOOL shutdown)
2229 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2230 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2232 if (*fdp < 0) return; /* TLS was not active */
2236 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2237 SSL_shutdown(*sslp);
2249 /*************************************************
2250 * Let tls_require_ciphers be checked at startup *
2251 *************************************************/
2253 /* The tls_require_ciphers option, if set, must be something which the
2256 Returns: NULL on success, or error message
2260 tls_validate_require_cipher(void)
2263 uschar *s, *expciphers, *err;
2265 /* this duplicates from tls_init(), we need a better "init just global
2266 state, for no specific purpose" singleton function of our own */
2268 SSL_load_error_strings();
2269 OpenSSL_add_ssl_algorithms();
2270 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2271 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2272 list of available digests. */
2273 EVP_add_digest(EVP_sha256());
2276 if (!(tls_require_ciphers && *tls_require_ciphers))
2279 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2280 return US"failed to expand tls_require_ciphers";
2282 if (!(expciphers && *expciphers))
2285 /* normalisation ripped from above */
2287 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2291 ctx = SSL_CTX_new(SSLv23_server_method());
2294 ERR_error_string(ERR_get_error(), ssl_errstring);
2295 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2299 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2301 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2303 ERR_error_string(ERR_get_error(), ssl_errstring);
2304 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2315 /*************************************************
2316 * Report the library versions. *
2317 *************************************************/
2319 /* There have historically been some issues with binary compatibility in
2320 OpenSSL libraries; if Exim (like many other applications) is built against
2321 one version of OpenSSL but the run-time linker picks up another version,
2322 it can result in serious failures, including crashing with a SIGSEGV. So
2323 report the version found by the compiler and the run-time version.
2325 Note: some OS vendors backport security fixes without changing the version
2326 number/string, and the version date remains unchanged. The _build_ date
2327 will change, so we can more usefully assist with version diagnosis by also
2328 reporting the build date.
2330 Arguments: a FILE* to print the results to
2335 tls_version_report(FILE *f)
2337 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2340 OPENSSL_VERSION_TEXT,
2341 SSLeay_version(SSLEAY_VERSION),
2342 SSLeay_version(SSLEAY_BUILT_ON));
2343 /* third line is 38 characters for the %s and the line is 73 chars long;
2344 the OpenSSL output includes a "built on: " prefix already. */
2350 /*************************************************
2351 * Random number generation *
2352 *************************************************/
2354 /* Pseudo-random number generation. The result is not expected to be
2355 cryptographically strong but not so weak that someone will shoot themselves
2356 in the foot using it as a nonce in input in some email header scheme or
2357 whatever weirdness they'll twist this into. The result should handle fork()
2358 and avoid repeating sequences. OpenSSL handles that for us.
2362 Returns a random number in range [0, max-1]
2366 vaguely_random_number(int max)
2370 static pid_t pidlast = 0;
2373 uschar smallbuf[sizeof(r)];
2379 if (pidnow != pidlast)
2381 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2382 is unique for each thread", this doesn't apparently apply across processes,
2383 so our own warning from vaguely_random_number_fallback() applies here too.
2384 Fix per PostgreSQL. */
2390 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2394 gettimeofday(&r.tv, NULL);
2397 RAND_seed((uschar *)(&r), sizeof(r));
2399 /* We're after pseudo-random, not random; if we still don't have enough data
2400 in the internal PRNG then our options are limited. We could sleep and hope
2401 for entropy to come along (prayer technique) but if the system is so depleted
2402 in the first place then something is likely to just keep taking it. Instead,
2403 we'll just take whatever little bit of pseudo-random we can still manage to
2406 needed_len = sizeof(r);
2407 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2408 asked for a number less than 10. */
2409 for (r = max, i = 0; r; ++i)
2415 /* We do not care if crypto-strong */
2416 i = RAND_pseudo_bytes(smallbuf, needed_len);
2420 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2421 return vaguely_random_number_fallback(max);
2425 for (p = smallbuf; needed_len; --needed_len, ++p)
2431 /* We don't particularly care about weighted results; if someone wants
2432 smooth distribution and cares enough then they should submit a patch then. */
2439 /*************************************************
2440 * OpenSSL option parse *
2441 *************************************************/
2443 /* Parse one option for tls_openssl_options_parse below
2446 name one option name
2447 value place to store a value for it
2448 Returns success or failure in parsing
2451 struct exim_openssl_option {
2455 /* We could use a macro to expand, but we need the ifdef and not all the
2456 options document which version they were introduced in. Policylet: include
2457 all options unless explicitly for DTLS, let the administrator choose which
2460 This list is current as of:
2462 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2464 static struct exim_openssl_option exim_openssl_options[] = {
2465 /* KEEP SORTED ALPHABETICALLY! */
2467 { US"all", SSL_OP_ALL },
2469 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2470 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2472 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2473 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2475 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2476 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2478 #ifdef SSL_OP_EPHEMERAL_RSA
2479 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2481 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2482 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2484 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2485 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2487 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2488 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2490 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2491 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2493 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2494 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2496 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2497 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2499 #ifdef SSL_OP_NO_COMPRESSION
2500 { US"no_compression", SSL_OP_NO_COMPRESSION },
2502 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2503 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2505 #ifdef SSL_OP_NO_SSLv2
2506 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2508 #ifdef SSL_OP_NO_SSLv3
2509 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2511 #ifdef SSL_OP_NO_TICKET
2512 { US"no_ticket", SSL_OP_NO_TICKET },
2514 #ifdef SSL_OP_NO_TLSv1
2515 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2517 #ifdef SSL_OP_NO_TLSv1_1
2518 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2519 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2520 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2522 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2525 #ifdef SSL_OP_NO_TLSv1_2
2526 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2528 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2529 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2531 #ifdef SSL_OP_SINGLE_DH_USE
2532 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2534 #ifdef SSL_OP_SINGLE_ECDH_USE
2535 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2537 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2538 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2540 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2541 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2543 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2544 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2546 #ifdef SSL_OP_TLS_D5_BUG
2547 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2549 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2550 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2553 static int exim_openssl_options_size =
2554 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2558 tls_openssl_one_option_parse(uschar *name, long *value)
2561 int last = exim_openssl_options_size;
2562 while (last > first)
2564 int middle = (first + last)/2;
2565 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2568 *value = exim_openssl_options[middle].value;
2582 /*************************************************
2583 * OpenSSL option parsing logic *
2584 *************************************************/
2586 /* OpenSSL has a number of compatibility options which an administrator might
2587 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2588 we look like log_selector.
2591 option_spec the administrator-supplied string of options
2592 results ptr to long storage for the options bitmap
2593 Returns success or failure
2597 tls_openssl_options_parse(uschar *option_spec, long *results)
2602 BOOL adding, item_parsed;
2605 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2606 * from default because it increases BEAST susceptibility. */
2607 #ifdef SSL_OP_NO_SSLv2
2608 result |= SSL_OP_NO_SSLv2;
2611 if (option_spec == NULL)
2617 for (s=option_spec; *s != '\0'; /**/)
2619 while (isspace(*s)) ++s;
2622 if (*s != '+' && *s != '-')
2624 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2625 "+ or - expected but found \"%s\"\n", s);
2628 adding = *s++ == '+';
2629 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2632 item_parsed = tls_openssl_one_option_parse(s, &item);
2635 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2638 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2639 adding ? "adding" : "removing", result, item, s);
2654 /* End of tls-openssl.c */