1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2014 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Portions Copyright (c) The OpenSSL Project 1999 */
10 /* This module provides the TLS (aka SSL) support for Exim using the OpenSSL
11 library. It is #included into the tls.c file when that library is used. The
12 code herein is based on a patch that was originally contributed by Steve
13 Haslam. It was adapted from stunnel, a GPL program by Michal Trojnara.
15 No cryptographic code is included in Exim. All this module does is to call
16 functions from the OpenSSL library. */
21 #include <openssl/lhash.h>
22 #include <openssl/ssl.h>
23 #include <openssl/err.h>
24 #include <openssl/rand.h>
26 # include <openssl/ocsp.h>
28 #ifdef EXPERIMENTAL_DANE
34 # define EXIM_OCSP_SKEW_SECONDS (300L)
35 # define EXIM_OCSP_MAX_AGE (-1L)
38 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
39 # define EXIM_HAVE_OPENSSL_TLSEXT
41 #if OPENSSL_VERSION_NUMBER >= 0x010100000L
42 # define EXIM_HAVE_OPENSSL_CHECKHOST
44 #if OPENSSL_VERSION_NUMBER >= 0x010000000L \
45 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
46 # define EXIM_HAVE_OPENSSL_CHECKHOST
49 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
50 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
54 /* Structure for collecting random data for seeding. */
56 typedef struct randstuff {
61 /* Local static variables */
63 static BOOL client_verify_callback_called = FALSE;
64 static BOOL server_verify_callback_called = FALSE;
65 static const uschar *sid_ctx = US"exim";
67 /* We have three different contexts to care about.
69 Simple case: client, `client_ctx`
70 As a client, we can be doing a callout or cut-through delivery while receiving
71 a message. So we have a client context, which should have options initialised
72 from the SMTP Transport.
75 There are two cases: with and without ServerNameIndication from the client.
76 Given TLS SNI, we can be using different keys, certs and various other
77 configuration settings, because they're re-expanded with $tls_sni set. This
78 allows vhosting with TLS. This SNI is sent in the handshake.
79 A client might not send SNI, so we need a fallback, and an initial setup too.
80 So as a server, we start out using `server_ctx`.
81 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
82 `server_sni` from `server_ctx` and then initialise settings by re-expanding
86 static SSL_CTX *client_ctx = NULL;
87 static SSL_CTX *server_ctx = NULL;
88 static SSL *client_ssl = NULL;
89 static SSL *server_ssl = NULL;
91 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
92 static SSL_CTX *server_sni = NULL;
95 static char ssl_errstring[256];
97 static int ssl_session_timeout = 200;
98 static BOOL client_verify_optional = FALSE;
99 static BOOL server_verify_optional = FALSE;
101 static BOOL reexpand_tls_files_for_sni = FALSE;
104 typedef struct tls_ext_ctx_cb {
112 uschar *file_expanded;
113 OCSP_RESPONSE *response;
116 X509_STORE *verify_store; /* non-null if status requested */
117 BOOL verify_required;
122 /* these are cached from first expand */
123 uschar *server_cipher_list;
124 /* only passed down to tls_error: */
127 #ifdef EXPERIMENTAL_CERTNAMES
128 uschar * verify_cert_hostnames;
130 #ifdef EXPERIMENTAL_EVENT
131 uschar * event_action;
135 /* should figure out a cleanup of API to handle state preserved per
136 implementation, for various reasons, which can be void * in the APIs.
137 For now, we hack around it. */
138 tls_ext_ctx_cb *client_static_cbinfo = NULL;
139 tls_ext_ctx_cb *server_static_cbinfo = NULL;
142 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
143 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
146 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
147 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
150 static int tls_server_stapling_cb(SSL *s, void *arg);
154 /*************************************************
156 *************************************************/
158 /* Called from lots of places when errors occur before actually starting to do
159 the TLS handshake, that is, while the session is still in clear. Always returns
160 DEFER for a server and FAIL for a client so that most calls can use "return
161 tls_error(...)" to do this processing and then give an appropriate return. A
162 single function is used for both server and client, because it is called from
163 some shared functions.
166 prefix text to include in the logged error
167 host NULL if setting up a server;
168 the connected host if setting up a client
169 msg error message or NULL if we should ask OpenSSL
171 Returns: OK/DEFER/FAIL
175 tls_error(uschar *prefix, host_item *host, uschar *msg)
179 ERR_error_string(ERR_get_error(), ssl_errstring);
180 msg = (uschar *)ssl_errstring;
185 log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection (%s): %s",
186 host->name, host->address, prefix, msg);
191 uschar *conn_info = smtp_get_connection_info();
192 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
194 /* I'd like to get separated H= here, but too hard for now */
195 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
196 conn_info, prefix, msg);
203 /*************************************************
204 * Callback to generate RSA key *
205 *************************************************/
213 Returns: pointer to generated key
217 rsa_callback(SSL *s, int export, int keylength)
220 export = export; /* Shut picky compilers up */
221 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
222 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
225 ERR_error_string(ERR_get_error(), ssl_errstring);
226 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
238 x509_store_dump_cert_s_names(X509_STORE * store)
240 STACK_OF(X509_OBJECT) * roots= store->objs;
242 static uschar name[256];
244 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
246 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
247 if(tmp_obj->type == X509_LU_X509)
249 X509 * current_cert= tmp_obj->data.x509;
250 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
251 debug_printf(" %s\n", name);
259 /*************************************************
260 * Callback for verification *
261 *************************************************/
263 /* The SSL library does certificate verification if set up to do so. This
264 callback has the current yes/no state is in "state". If verification succeeded,
265 we set up the tls_peerdn string. If verification failed, what happens depends
266 on whether the client is required to present a verifiable certificate or not.
268 If verification is optional, we change the state to yes, but still log the
269 verification error. For some reason (it really would help to have proper
270 documentation of OpenSSL), this callback function then gets called again, this
271 time with state = 1. In fact, that's useful, because we can set up the peerdn
272 value, but we must take care not to set the private verified flag on the second
275 Note: this function is not called if the client fails to present a certificate
276 when asked. We get here only if a certificate has been received. Handling of
277 optional verification for this case is done when requesting SSL to verify, by
278 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
280 May be called multiple times for different issues with a certificate, even
281 for a given "depth" in the certificate chain.
284 state current yes/no state as 1/0
285 x509ctx certificate information.
286 client TRUE for client startup, FALSE for server startup
288 Returns: 1 if verified, 0 if not
292 verify_callback(int state, X509_STORE_CTX *x509ctx,
293 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
295 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
296 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
298 static uschar txt[256];
300 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
304 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
306 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
308 tlsp->certificate_verified = FALSE;
312 tlsp->peercert = X509_dup(cert);
313 return 0; /* reject */
315 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
316 "tls_try_verify_hosts)\n");
321 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
323 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
324 { /* client, wanting stapling */
325 /* Add the server cert's signing chain as the one
326 for the verification of the OCSP stapled information. */
328 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
333 #ifdef EXPERIMENTAL_EVENT
334 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
337 tlsp->peercert = X509_dup(cert);
338 if (event_raise(ev, US"tls:cert", string_sprintf("%d", depth)) == DEFER)
340 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
341 "depth=%d cert=%s", depth, txt);
342 tlsp->certificate_verified = FALSE;
344 return 0; /* reject */
346 X509_free(tlsp->peercert);
347 tlsp->peercert = NULL;
353 #ifdef EXPERIMENTAL_CERTNAMES
354 uschar * verify_cert_hostnames;
358 tlsp->peercert = X509_dup(cert);
360 #ifdef EXPERIMENTAL_CERTNAMES
361 if ( tlsp == &tls_out
362 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
363 /* client, wanting hostname check */
365 # if EXIM_HAVE_OPENSSL_CHECKHOST
366 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
367 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
371 uschar * list = verify_cert_hostnames;
374 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
375 if ((rc = X509_check_host(cert, name, 0,
376 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)))
380 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
387 log_write(0, LOG_MAIN,
388 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
389 return 0; /* reject */
393 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
395 log_write(0, LOG_MAIN,
396 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
397 return 0; /* reject */
400 #endif /*EXPERIMENTAL_CERTNAMES*/
402 #ifdef EXPERIMENTAL_EVENT
403 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
405 if (event_raise(ev, US"tls:cert", US"0") == DEFER)
407 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
408 "depth=0 cert=%s", txt);
409 tlsp->certificate_verified = FALSE;
411 return 0; /* reject */
415 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
416 *calledp ? "" : " authenticated", txt);
417 if (!*calledp) tlsp->certificate_verified = TRUE;
421 return 1; /* accept, at least for this level */
425 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
427 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
431 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
433 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
437 #ifdef EXPERIMENTAL_DANE
439 /* This gets called *by* the dane library verify callback, which interposes
443 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
445 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
446 static uschar txt[256];
447 #ifdef EXPERIMENTAL_EVENT
448 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
451 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
453 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
454 tls_out.peerdn = txt;
455 tls_out.peercert = X509_dup(cert);
457 #ifdef EXPERIMENTAL_EVENT
458 if (client_static_cbinfo->event_action)
460 if (event_raise(client_static_cbinfo->event_action,
461 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
463 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
464 "depth=%d cert=%s", depth, txt);
465 tls_out.certificate_verified = FALSE;
466 return 0; /* reject */
470 X509_free(tls_out.peercert);
471 tls_out.peercert = NULL;
477 tls_out.dane_verified =
478 tls_out.certificate_verified = TRUE;
482 #endif /*EXPERIMENTAL_DANE*/
485 /*************************************************
486 * Information callback *
487 *************************************************/
489 /* The SSL library functions call this from time to time to indicate what they
490 are doing. We copy the string to the debugging output when TLS debugging has
502 info_callback(SSL *s, int where, int ret)
506 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
511 /*************************************************
512 * Initialize for DH *
513 *************************************************/
515 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
518 dhparam DH parameter file or fixed parameter identity string
519 host connected host, if client; NULL if server
521 Returns: TRUE if OK (nothing to set up, or setup worked)
525 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
532 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
535 if (!dhexpanded || !*dhexpanded)
536 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
537 else if (dhexpanded[0] == '/')
539 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
541 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
542 host, US strerror(errno));
548 if (Ustrcmp(dhexpanded, "none") == 0)
550 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
554 if (!(pem = std_dh_prime_named(dhexpanded)))
556 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
557 host, US strerror(errno));
560 bio = BIO_new_mem_buf(CS pem, -1);
563 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
566 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
571 /* Even if it is larger, we silently return success rather than cause things
572 * to fail out, so that a too-large DH will not knock out all TLS; it's a
573 * debatable choice. */
574 if ((8*DH_size(dh)) > tls_dh_max_bits)
577 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
578 8*DH_size(dh), tls_dh_max_bits);
582 SSL_CTX_set_tmp_dh(sctx, dh);
584 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
585 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
598 /*************************************************
599 * Load OCSP information into state *
600 *************************************************/
602 /* Called to load the server OCSP response from the given file into memory, once
603 caller has determined this is needed. Checks validity. Debugs a message
606 ASSUMES: single response, for single cert.
609 sctx the SSL_CTX* to update
610 cbinfo various parts of session state
611 expanded the filename putatively holding an OCSP response
616 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
620 OCSP_BASICRESP *basic_response;
621 OCSP_SINGLERESP *single_response;
622 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
624 unsigned long verify_flags;
625 int status, reason, i;
627 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
628 if (cbinfo->u_ocsp.server.response)
630 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
631 cbinfo->u_ocsp.server.response = NULL;
634 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
637 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
638 cbinfo->u_ocsp.server.file_expanded);
642 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
646 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
650 status = OCSP_response_status(resp);
651 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
653 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
654 OCSP_response_status_str(status), status);
658 basic_response = OCSP_response_get1_basic(resp);
662 debug_printf("OCSP response parse error: unable to extract basic response.\n");
666 store = SSL_CTX_get_cert_store(sctx);
667 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
669 /* May need to expose ability to adjust those flags?
670 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
671 OCSP_TRUSTOTHER OCSP_NOINTERN */
673 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
677 ERR_error_string(ERR_get_error(), ssl_errstring);
678 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
683 /* Here's the simplifying assumption: there's only one response, for the
684 one certificate we use, and nothing for anything else in a chain. If this
685 proves false, we need to extract a cert id from our issued cert
686 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
687 right cert in the stack and then calls OCSP_single_get0_status()).
689 I'm hoping to avoid reworking a bunch more of how we handle state here. */
690 single_response = OCSP_resp_get0(basic_response, 0);
691 if (!single_response)
694 debug_printf("Unable to get first response from OCSP basic response.\n");
698 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
699 if (status != V_OCSP_CERTSTATUS_GOOD)
701 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
702 OCSP_cert_status_str(status), status,
703 OCSP_crl_reason_str(reason), reason);
707 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
709 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
714 cbinfo->u_ocsp.server.response = resp;
718 if (running_in_test_harness)
720 extern char ** environ;
722 for (p = USS environ; *p != NULL; p++)
723 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
725 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
726 goto supply_response;
731 #endif /*!DISABLE_OCSP*/
736 /*************************************************
737 * Expand key and cert file specs *
738 *************************************************/
740 /* Called once during tls_init and possibly again during TLS setup, for a
741 new context, if Server Name Indication was used and tls_sni was seen in
742 the certificate string.
745 sctx the SSL_CTX* to update
746 cbinfo various parts of session state
748 Returns: OK/DEFER/FAIL
752 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
756 if (cbinfo->certificate == NULL)
759 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
760 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
761 Ustrstr(cbinfo->certificate, US"tls_out_sni")
763 reexpand_tls_files_for_sni = TRUE;
765 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
768 if (expanded != NULL)
770 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
771 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
772 return tls_error(string_sprintf(
773 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
777 if (cbinfo->privatekey != NULL &&
778 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
781 /* If expansion was forced to fail, key_expanded will be NULL. If the result
782 of the expansion is an empty string, ignore it also, and assume the private
783 key is in the same file as the certificate. */
785 if (expanded != NULL && *expanded != 0)
787 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
788 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
789 return tls_error(string_sprintf(
790 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
794 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
796 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
799 if (expanded != NULL && *expanded != 0)
801 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
802 if (cbinfo->u_ocsp.server.file_expanded &&
803 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
806 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
808 ocsp_load_response(sctx, cbinfo, expanded);
820 /*************************************************
821 * Callback to handle SNI *
822 *************************************************/
824 /* Called when acting as server during the TLS session setup if a Server Name
825 Indication extension was sent by the client.
827 API documentation is OpenSSL s_server.c implementation.
830 s SSL* of the current session
831 ad unknown (part of OpenSSL API) (unused)
832 arg Callback of "our" registered data
834 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
837 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
839 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
841 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
842 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
844 int old_pool = store_pool;
847 return SSL_TLSEXT_ERR_OK;
849 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
850 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
852 /* Make the extension value available for expansion */
853 store_pool = POOL_PERM;
854 tls_in.sni = string_copy(US servername);
855 store_pool = old_pool;
857 if (!reexpand_tls_files_for_sni)
858 return SSL_TLSEXT_ERR_OK;
860 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
861 not confident that memcpy wouldn't break some internal reference counting.
862 Especially since there's a references struct member, which would be off. */
864 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
866 ERR_error_string(ERR_get_error(), ssl_errstring);
867 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
868 return SSL_TLSEXT_ERR_NOACK;
871 /* Not sure how many of these are actually needed, since SSL object
872 already exists. Might even need this selfsame callback, for reneg? */
874 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
875 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
876 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
877 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
878 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
879 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
880 if (cbinfo->server_cipher_list)
881 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
883 if (cbinfo->u_ocsp.server.file)
885 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
886 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
890 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
891 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
893 /* do this after setup_certs, because this can require the certs for verifying
895 rc = tls_expand_session_files(server_sni, cbinfo);
896 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
898 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
899 return SSL_TLSEXT_ERR_NOACK;
901 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
902 SSL_set_SSL_CTX(s, server_sni);
904 return SSL_TLSEXT_ERR_OK;
906 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
913 /*************************************************
914 * Callback to handle OCSP Stapling *
915 *************************************************/
917 /* Called when acting as server during the TLS session setup if the client
918 requests OCSP information with a Certificate Status Request.
920 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
926 tls_server_stapling_cb(SSL *s, void *arg)
928 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
929 uschar *response_der;
930 int response_der_len;
933 debug_printf("Received TLS status request (OCSP stapling); %s response.",
934 cbinfo->u_ocsp.server.response ? "have" : "lack");
936 tls_in.ocsp = OCSP_NOT_RESP;
937 if (!cbinfo->u_ocsp.server.response)
938 return SSL_TLSEXT_ERR_NOACK;
941 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
943 if (response_der_len <= 0)
944 return SSL_TLSEXT_ERR_NOACK;
946 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
947 tls_in.ocsp = OCSP_VFIED;
948 return SSL_TLSEXT_ERR_OK;
953 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
955 BIO_printf(bp, "\t%s: ", str);
956 ASN1_GENERALIZEDTIME_print(bp, time);
961 tls_client_stapling_cb(SSL *s, void *arg)
963 tls_ext_ctx_cb * cbinfo = arg;
964 const unsigned char * p;
970 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
971 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
974 /* Expect this when we requested ocsp but got none */
975 if ( cbinfo->u_ocsp.client.verify_required
976 && log_extra_selector & LX_tls_cipher)
977 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
979 DEBUG(D_tls) debug_printf(" null\n");
980 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
983 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
985 tls_out.ocsp = OCSP_FAILED;
986 if (log_extra_selector & LX_tls_cipher)
987 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
989 DEBUG(D_tls) debug_printf(" parse error\n");
993 if(!(bs = OCSP_response_get1_basic(rsp)))
995 tls_out.ocsp = OCSP_FAILED;
996 if (log_extra_selector & LX_tls_cipher)
997 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
999 DEBUG(D_tls) debug_printf(" error parsing response\n");
1000 OCSP_RESPONSE_free(rsp);
1004 /* We'd check the nonce here if we'd put one in the request. */
1005 /* However that would defeat cacheability on the server so we don't. */
1007 /* This section of code reworked from OpenSSL apps source;
1008 The OpenSSL Project retains copyright:
1009 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1014 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1016 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1018 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1020 /* Use the chain that verified the server cert to verify the stapled info */
1021 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1023 if ((i = OCSP_basic_verify(bs, NULL,
1024 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1026 tls_out.ocsp = OCSP_FAILED;
1027 if (log_extra_selector & LX_tls_cipher)
1028 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1029 BIO_printf(bp, "OCSP response verify failure\n");
1030 ERR_print_errors(bp);
1031 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1035 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1038 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1039 OCSP_SINGLERESP * single;
1041 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1043 tls_out.ocsp = OCSP_FAILED;
1044 log_write(0, LOG_MAIN, "OCSP stapling "
1045 "with multiple responses not handled");
1046 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1049 single = OCSP_resp_get0(bs, 0);
1050 status = OCSP_single_get0_status(single, &reason, &rev,
1051 &thisupd, &nextupd);
1054 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1055 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1056 if (!OCSP_check_validity(thisupd, nextupd,
1057 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1059 tls_out.ocsp = OCSP_FAILED;
1060 DEBUG(D_tls) ERR_print_errors(bp);
1061 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1062 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1066 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1067 OCSP_cert_status_str(status));
1070 case V_OCSP_CERTSTATUS_GOOD:
1071 tls_out.ocsp = OCSP_VFIED;
1074 case V_OCSP_CERTSTATUS_REVOKED:
1075 tls_out.ocsp = OCSP_FAILED;
1076 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1077 reason != -1 ? "; reason: " : "",
1078 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1079 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1080 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1083 tls_out.ocsp = OCSP_FAILED;
1084 log_write(0, LOG_MAIN,
1085 "Server certificate status unknown, in OCSP stapling");
1086 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1094 OCSP_RESPONSE_free(rsp);
1097 #endif /*!DISABLE_OCSP*/
1100 /*************************************************
1101 * Initialize for TLS *
1102 *************************************************/
1104 /* Called from both server and client code, to do preliminary initialization
1105 of the library. We allocate and return a context structure.
1108 ctxp returned SSL context
1109 host connected host, if client; NULL if server
1110 dhparam DH parameter file
1111 certificate certificate file
1112 privatekey private key
1113 ocsp_file file of stapling info (server); flag for require ocsp (client)
1114 addr address if client; NULL if server (for some randomness)
1115 cbp place to put allocated callback context
1117 Returns: OK/DEFER/FAIL
1121 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1123 #ifndef DISABLE_OCSP
1126 address_item *addr, tls_ext_ctx_cb ** cbp)
1131 tls_ext_ctx_cb * cbinfo;
1133 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1134 cbinfo->certificate = certificate;
1135 cbinfo->privatekey = privatekey;
1136 #ifndef DISABLE_OCSP
1137 if ((cbinfo->is_server = host==NULL))
1139 cbinfo->u_ocsp.server.file = ocsp_file;
1140 cbinfo->u_ocsp.server.file_expanded = NULL;
1141 cbinfo->u_ocsp.server.response = NULL;
1144 cbinfo->u_ocsp.client.verify_store = NULL;
1146 cbinfo->dhparam = dhparam;
1147 cbinfo->server_cipher_list = NULL;
1148 cbinfo->host = host;
1149 #ifdef EXPERIMENTAL_EVENT
1150 cbinfo->event_action = NULL;
1153 SSL_load_error_strings(); /* basic set up */
1154 OpenSSL_add_ssl_algorithms();
1156 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1157 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1158 list of available digests. */
1159 EVP_add_digest(EVP_sha256());
1162 /* Create a context.
1163 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1164 negotiation in the different methods; as far as I can tell, the only
1165 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1166 when OpenSSL is built without SSLv2 support.
1167 By disabling with openssl_options, we can let admins re-enable with the
1170 *ctxp = SSL_CTX_new((host == NULL)?
1171 SSLv23_server_method() : SSLv23_client_method());
1173 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1175 /* It turns out that we need to seed the random number generator this early in
1176 order to get the full complement of ciphers to work. It took me roughly a day
1177 of work to discover this by experiment.
1179 On systems that have /dev/urandom, SSL may automatically seed itself from
1180 there. Otherwise, we have to make something up as best we can. Double check
1186 gettimeofday(&r.tv, NULL);
1189 RAND_seed((uschar *)(&r), sizeof(r));
1190 RAND_seed((uschar *)big_buffer, big_buffer_size);
1191 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1194 return tls_error(US"RAND_status", host,
1195 US"unable to seed random number generator");
1198 /* Set up the information callback, which outputs if debugging is at a suitable
1201 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1203 /* Automatically re-try reads/writes after renegotiation. */
1204 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1206 /* Apply administrator-supplied work-arounds.
1207 Historically we applied just one requested option,
1208 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1209 moved to an administrator-controlled list of options to specify and
1210 grandfathered in the first one as the default value for "openssl_options".
1212 No OpenSSL version number checks: the options we accept depend upon the
1213 availability of the option value macros from OpenSSL. */
1215 okay = tls_openssl_options_parse(openssl_options, &init_options);
1217 return tls_error(US"openssl_options parsing failed", host, NULL);
1221 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1222 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1223 return tls_error(string_sprintf(
1224 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1227 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1229 /* Initialize with DH parameters if supplied */
1231 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1233 /* Set up certificate and key (and perhaps OCSP info) */
1235 rc = tls_expand_session_files(*ctxp, cbinfo);
1236 if (rc != OK) return rc;
1238 /* If we need to handle SNI, do so */
1239 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1240 if (host == NULL) /* server */
1242 # ifndef DISABLE_OCSP
1243 /* We check u_ocsp.server.file, not server.response, because we care about if
1244 the option exists, not what the current expansion might be, as SNI might
1245 change the certificate and OCSP file in use between now and the time the
1246 callback is invoked. */
1247 if (cbinfo->u_ocsp.server.file)
1249 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1250 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1253 /* We always do this, so that $tls_sni is available even if not used in
1255 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1256 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1258 # ifndef DISABLE_OCSP
1260 if(ocsp_file) /* wanting stapling */
1262 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1264 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1267 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1268 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1273 #ifdef EXPERIMENTAL_CERTNAMES
1274 cbinfo->verify_cert_hostnames = NULL;
1277 /* Set up the RSA callback */
1279 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1281 /* Finally, set the timeout, and we are done */
1283 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1284 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1294 /*************************************************
1295 * Get name of cipher in use *
1296 *************************************************/
1299 Argument: pointer to an SSL structure for the connection
1300 buffer to use for answer
1302 pointer to number of bits for cipher
1307 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1309 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1310 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1311 the accessor functions use const in the prototype. */
1312 const SSL_CIPHER *c;
1315 ver = (const uschar *)SSL_get_version(ssl);
1317 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1318 SSL_CIPHER_get_bits(c, bits);
1320 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1321 SSL_CIPHER_get_name(c), *bits);
1323 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1330 /*************************************************
1331 * Set up for verifying certificates *
1332 *************************************************/
1334 /* Called by both client and server startup
1337 sctx SSL_CTX* to initialise
1338 certs certs file or NULL
1339 crl CRL file or NULL
1340 host NULL in a server; the remote host in a client
1341 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1342 otherwise passed as FALSE
1343 cert_vfy_cb Callback function for certificate verification
1345 Returns: OK/DEFER/FAIL
1349 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1350 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1352 uschar *expcerts, *expcrl;
1354 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1357 if (expcerts != NULL && *expcerts != '\0')
1359 struct stat statbuf;
1360 if (!SSL_CTX_set_default_verify_paths(sctx))
1361 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1363 if (Ustat(expcerts, &statbuf) < 0)
1365 log_write(0, LOG_MAIN|LOG_PANIC,
1366 "failed to stat %s for certificates", expcerts);
1372 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1373 { file = NULL; dir = expcerts; }
1375 { file = expcerts; dir = NULL; }
1377 /* If a certificate file is empty, the next function fails with an
1378 unhelpful error message. If we skip it, we get the correct behaviour (no
1379 certificates are recognized, but the error message is still misleading (it
1380 says no certificate was supplied.) But this is better. */
1382 if ((file == NULL || statbuf.st_size > 0) &&
1383 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1384 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1386 /* Load the list of CAs for which we will accept certs, for sending
1387 to the client. This is only for the one-file tls_verify_certificates
1389 If a list isn't loaded into the server, but
1390 some verify locations are set, the server end appears to make
1391 a wildcard reqest for client certs.
1392 Meanwhile, the client library as deafult behaviour *ignores* the list
1393 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1394 Because of this, and that the dir variant is likely only used for
1395 the public-CA bundle (not for a private CA), not worth fixing.
1399 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1400 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1401 sk_X509_NAME_num(names));
1402 SSL_CTX_set_client_CA_list(sctx, names);
1406 /* Handle a certificate revocation list. */
1408 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1410 /* This bit of code is now the version supplied by Lars Mainka. (I have
1411 * merely reformatted it into the Exim code style.)
1413 * "From here I changed the code to add support for multiple crl's
1414 * in pem format in one file or to support hashed directory entries in
1415 * pem format instead of a file. This method now uses the library function
1416 * X509_STORE_load_locations to add the CRL location to the SSL context.
1417 * OpenSSL will then handle the verify against CA certs and CRLs by
1418 * itself in the verify callback." */
1420 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1421 if (expcrl != NULL && *expcrl != 0)
1423 struct stat statbufcrl;
1424 if (Ustat(expcrl, &statbufcrl) < 0)
1426 log_write(0, LOG_MAIN|LOG_PANIC,
1427 "failed to stat %s for certificates revocation lists", expcrl);
1432 /* is it a file or directory? */
1434 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1435 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1439 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1445 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1447 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1448 return tls_error(US"X509_STORE_load_locations", host, NULL);
1450 /* setting the flags to check against the complete crl chain */
1452 X509_STORE_set_flags(cvstore,
1453 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1457 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1459 /* If verification is optional, don't fail if no certificate */
1461 SSL_CTX_set_verify(sctx,
1462 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1471 /*************************************************
1472 * Start a TLS session in a server *
1473 *************************************************/
1475 /* This is called when Exim is running as a server, after having received
1476 the STARTTLS command. It must respond to that command, and then negotiate
1480 require_ciphers allowed ciphers
1482 Returns: OK on success
1483 DEFER for errors before the start of the negotiation
1484 FAIL for errors during the negotation; the server can't
1489 tls_server_start(const uschar *require_ciphers)
1493 tls_ext_ctx_cb *cbinfo;
1494 static uschar cipherbuf[256];
1496 /* Check for previous activation */
1498 if (tls_in.active >= 0)
1500 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1501 smtp_printf("554 Already in TLS\r\n");
1505 /* Initialize the SSL library. If it fails, it will already have logged
1508 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1509 #ifndef DISABLE_OCSP
1512 NULL, &server_static_cbinfo);
1513 if (rc != OK) return rc;
1514 cbinfo = server_static_cbinfo;
1516 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1519 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1520 were historically separated by underscores. So that I can use either form in my
1521 tests, and also for general convenience, we turn underscores into hyphens here.
1524 if (expciphers != NULL)
1526 uschar *s = expciphers;
1527 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1528 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1529 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1530 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1531 cbinfo->server_cipher_list = expciphers;
1534 /* If this is a host for which certificate verification is mandatory or
1535 optional, set up appropriately. */
1537 tls_in.certificate_verified = FALSE;
1538 #ifdef EXPERIMENTAL_DANE
1539 tls_in.dane_verified = FALSE;
1541 server_verify_callback_called = FALSE;
1543 if (verify_check_host(&tls_verify_hosts) == OK)
1545 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1546 FALSE, verify_callback_server);
1547 if (rc != OK) return rc;
1548 server_verify_optional = FALSE;
1550 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1552 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1553 TRUE, verify_callback_server);
1554 if (rc != OK) return rc;
1555 server_verify_optional = TRUE;
1558 /* Prepare for new connection */
1560 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1562 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1564 * With the SSL_clear(), we get strange interoperability bugs with
1565 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1566 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1568 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1569 * session shutdown. In this case, we have a brand new object and there's no
1570 * obvious reason to immediately clear it. I'm guessing that this was
1571 * originally added because of incomplete initialisation which the clear fixed,
1572 * in some historic release.
1575 /* Set context and tell client to go ahead, except in the case of TLS startup
1576 on connection, where outputting anything now upsets the clients and tends to
1577 make them disconnect. We need to have an explicit fflush() here, to force out
1578 the response. Other smtp_printf() calls do not need it, because in non-TLS
1579 mode, the fflush() happens when smtp_getc() is called. */
1581 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1582 if (!tls_in.on_connect)
1584 smtp_printf("220 TLS go ahead\r\n");
1588 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1589 that the OpenSSL library doesn't. */
1591 SSL_set_wfd(server_ssl, fileno(smtp_out));
1592 SSL_set_rfd(server_ssl, fileno(smtp_in));
1593 SSL_set_accept_state(server_ssl);
1595 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1597 sigalrm_seen = FALSE;
1598 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1599 rc = SSL_accept(server_ssl);
1604 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1605 if (ERR_get_error() == 0)
1606 log_write(0, LOG_MAIN,
1607 "TLS client disconnected cleanly (rejected our certificate?)");
1611 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1613 /* TLS has been set up. Adjust the input functions to read via TLS,
1614 and initialize things. */
1616 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1617 tls_in.cipher = cipherbuf;
1622 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1623 debug_printf("Shared ciphers: %s\n", buf);
1626 /* Record the certificate we presented */
1628 X509 * crt = SSL_get_certificate(server_ssl);
1629 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1632 /* Only used by the server-side tls (tls_in), including tls_getc.
1633 Client-side (tls_out) reads (seem to?) go via
1634 smtp_read_response()/ip_recv().
1635 Hence no need to duplicate for _in and _out.
1637 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1638 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1639 ssl_xfer_eof = ssl_xfer_error = 0;
1641 receive_getc = tls_getc;
1642 receive_ungetc = tls_ungetc;
1643 receive_feof = tls_feof;
1644 receive_ferror = tls_ferror;
1645 receive_smtp_buffered = tls_smtp_buffered;
1647 tls_in.active = fileno(smtp_out);
1655 tls_client_basic_ctx_init(SSL_CTX * ctx,
1656 host_item * host, smtp_transport_options_block * ob
1657 #ifdef EXPERIMENTAL_CERTNAMES
1658 , tls_ext_ctx_cb * cbinfo
1663 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1664 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1665 the specified host patterns if one of them is defined */
1667 if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1668 (verify_check_host(&ob->tls_verify_hosts) == OK))
1670 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1671 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1673 client_verify_optional = FALSE;
1675 #ifdef EXPERIMENTAL_CERTNAMES
1676 if (ob->tls_verify_cert_hostnames)
1678 if (!expand_check(ob->tls_verify_cert_hostnames,
1679 US"tls_verify_cert_hostnames",
1680 &cbinfo->verify_cert_hostnames))
1682 if (cbinfo->verify_cert_hostnames)
1683 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1684 cbinfo->verify_cert_hostnames);
1688 else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1690 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1691 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1693 client_verify_optional = TRUE;
1700 #ifdef EXPERIMENTAL_DANE
1702 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1706 const char * hostnames[2] = { CS host->name, NULL };
1709 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1710 return tls_error(US"hostnames load", host, NULL);
1712 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1714 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1715 ) if (rr->type == T_TLSA)
1717 uschar * p = rr->data;
1718 uint8_t usage, selector, mtype;
1719 const char * mdname;
1723 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1724 if (usage != 2 && usage != 3) continue;
1731 default: continue; /* Only match-types 0, 1, 2 are supported */
1732 case 0: mdname = NULL; break;
1733 case 1: mdname = "sha256"; break;
1734 case 2: mdname = "sha512"; break;
1738 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1741 case 0: /* action not taken */
1742 return tls_error(US"tlsa load", host, NULL);
1746 tls_out.tlsa_usage |= 1<<usage;
1752 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1755 #endif /*EXPERIMENTAL_DANE*/
1759 /*************************************************
1760 * Start a TLS session in a client *
1761 *************************************************/
1763 /* Called from the smtp transport after STARTTLS has been accepted.
1766 fd the fd of the connection
1767 host connected host (for messages)
1768 addr the first address
1769 tb transport (always smtp)
1770 tlsa_dnsa tlsa lookup, if DANE, else null
1772 Returns: OK on success
1773 FAIL otherwise - note that tls_error() will not give DEFER
1774 because this is not a server
1778 tls_client_start(int fd, host_item *host, address_item *addr,
1779 transport_instance *tb
1780 #ifdef EXPERIMENTAL_DANE
1781 , dns_answer * tlsa_dnsa
1785 smtp_transport_options_block * ob =
1786 (smtp_transport_options_block *)tb->options_block;
1787 static uschar txt[256];
1788 uschar * expciphers;
1791 static uschar cipherbuf[256];
1793 #ifndef DISABLE_OCSP
1794 BOOL request_ocsp = FALSE;
1795 BOOL require_ocsp = FALSE;
1798 #ifdef EXPERIMENTAL_DANE
1799 tls_out.tlsa_usage = 0;
1802 #ifndef DISABLE_OCSP
1804 # ifdef EXPERIMENTAL_DANE
1806 && ob->hosts_request_ocsp[0] == '*'
1807 && ob->hosts_request_ocsp[1] == '\0'
1810 /* Unchanged from default. Use a safer one under DANE */
1811 request_ocsp = TRUE;
1812 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1813 " {= {4}{$tls_out_tlsa_usage}} } "
1818 if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1819 NULL, host->name, host->address, NULL) == OK))
1820 request_ocsp = TRUE;
1822 # ifdef EXPERIMENTAL_DANE
1825 request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
1826 NULL, host->name, host->address, NULL) == OK;
1830 rc = tls_init(&client_ctx, host, NULL,
1831 ob->tls_certificate, ob->tls_privatekey,
1832 #ifndef DISABLE_OCSP
1833 (void *)(long)request_ocsp,
1835 addr, &client_static_cbinfo);
1836 if (rc != OK) return rc;
1838 tls_out.certificate_verified = FALSE;
1839 client_verify_callback_called = FALSE;
1841 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1845 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1846 are separated by underscores. So that I can use either form in my tests, and
1847 also for general convenience, we turn underscores into hyphens here. */
1849 if (expciphers != NULL)
1851 uschar *s = expciphers;
1852 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1853 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1854 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1855 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1858 #ifdef EXPERIMENTAL_DANE
1861 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1863 if (!DANESSL_library_init())
1864 return tls_error(US"library init", host, NULL);
1865 if (DANESSL_CTX_init(client_ctx) <= 0)
1866 return tls_error(US"context init", host, NULL);
1872 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
1873 #ifdef EXPERIMENTAL_CERTNAMES
1874 , client_static_cbinfo
1879 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1880 return tls_error(US"SSL_new", host, NULL);
1881 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1882 SSL_set_fd(client_ssl, fd);
1883 SSL_set_connect_state(client_ssl);
1887 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1889 if (tls_out.sni == NULL)
1891 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1893 else if (!Ustrlen(tls_out.sni))
1897 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1898 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1899 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1902 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1908 #ifdef EXPERIMENTAL_DANE
1910 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1914 #ifndef DISABLE_OCSP
1915 /* Request certificate status at connection-time. If the server
1916 does OCSP stapling we will get the callback (set in tls_init()) */
1917 # ifdef EXPERIMENTAL_DANE
1921 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1922 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1924 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1925 this means we avoid the OCSP request, we wasted the setup
1926 cost in tls_init(). */
1927 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1928 NULL, host->name, host->address, NULL) == OK;
1929 request_ocsp = require_ocsp ? TRUE
1930 : verify_check_this_host(&ob->hosts_request_ocsp,
1931 NULL, host->name, host->address, NULL) == OK;
1938 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1939 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1940 tls_out.ocsp = OCSP_NOT_RESP;
1944 #ifdef EXPERIMENTAL_EVENT
1945 client_static_cbinfo->event_action = tb->event_action;
1948 /* There doesn't seem to be a built-in timeout on connection. */
1950 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1951 sigalrm_seen = FALSE;
1952 alarm(ob->command_timeout);
1953 rc = SSL_connect(client_ssl);
1956 #ifdef EXPERIMENTAL_DANE
1958 DANESSL_cleanup(client_ssl);
1962 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1964 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1966 /* Beware anonymous ciphers which lead to server_cert being NULL */
1967 /*XXX server_cert is never freed... use X509_free() */
1968 server_cert = SSL_get_peer_certificate (client_ssl);
1971 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1972 CS txt, sizeof(txt));
1973 tls_out.peerdn = txt; /*XXX a static buffer... */
1976 tls_out.peerdn = NULL;
1978 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1979 tls_out.cipher = cipherbuf;
1981 /* Record the certificate we presented */
1983 X509 * crt = SSL_get_certificate(client_ssl);
1984 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
1987 tls_out.active = fd;
1995 /*************************************************
1996 * TLS version of getc *
1997 *************************************************/
1999 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2000 it refills the buffer via the SSL reading function.
2003 Returns: the next character or EOF
2005 Only used by the server-side TLS.
2011 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2016 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2017 ssl_xfer_buffer, ssl_xfer_buffer_size);
2019 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2020 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2021 error = SSL_get_error(server_ssl, inbytes);
2024 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2025 closed down, not that the socket itself has been closed down. Revert to
2026 non-SSL handling. */
2028 if (error == SSL_ERROR_ZERO_RETURN)
2030 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2032 receive_getc = smtp_getc;
2033 receive_ungetc = smtp_ungetc;
2034 receive_feof = smtp_feof;
2035 receive_ferror = smtp_ferror;
2036 receive_smtp_buffered = smtp_buffered;
2038 SSL_free(server_ssl);
2042 tls_in.cipher = NULL;
2043 tls_in.peerdn = NULL;
2049 /* Handle genuine errors */
2051 else if (error == SSL_ERROR_SSL)
2053 ERR_error_string(ERR_get_error(), ssl_errstring);
2054 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2059 else if (error != SSL_ERROR_NONE)
2061 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2066 #ifndef DISABLE_DKIM
2067 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2069 ssl_xfer_buffer_hwm = inbytes;
2070 ssl_xfer_buffer_lwm = 0;
2073 /* Something in the buffer; return next uschar */
2075 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2080 /*************************************************
2081 * Read bytes from TLS channel *
2082 *************************************************/
2089 Returns: the number of bytes read
2090 -1 after a failed read
2092 Only used by the client-side TLS.
2096 tls_read(BOOL is_server, uschar *buff, size_t len)
2098 SSL *ssl = is_server ? server_ssl : client_ssl;
2102 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2103 buff, (unsigned int)len);
2105 inbytes = SSL_read(ssl, CS buff, len);
2106 error = SSL_get_error(ssl, inbytes);
2108 if (error == SSL_ERROR_ZERO_RETURN)
2110 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2113 else if (error != SSL_ERROR_NONE)
2125 /*************************************************
2126 * Write bytes down TLS channel *
2127 *************************************************/
2131 is_server channel specifier
2135 Returns: the number of bytes after a successful write,
2136 -1 after a failed write
2138 Used by both server-side and client-side TLS.
2142 tls_write(BOOL is_server, const uschar *buff, size_t len)
2147 SSL *ssl = is_server ? server_ssl : client_ssl;
2149 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2152 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2153 outbytes = SSL_write(ssl, CS buff, left);
2154 error = SSL_get_error(ssl, outbytes);
2155 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2159 ERR_error_string(ERR_get_error(), ssl_errstring);
2160 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2163 case SSL_ERROR_NONE:
2168 case SSL_ERROR_ZERO_RETURN:
2169 log_write(0, LOG_MAIN, "SSL channel closed on write");
2172 case SSL_ERROR_SYSCALL:
2173 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2174 sender_fullhost ? sender_fullhost : US"<unknown>",
2178 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2187 /*************************************************
2188 * Close down a TLS session *
2189 *************************************************/
2191 /* This is also called from within a delivery subprocess forked from the
2192 daemon, to shut down the TLS library, without actually doing a shutdown (which
2193 would tamper with the SSL session in the parent process).
2195 Arguments: TRUE if SSL_shutdown is to be called
2198 Used by both server-side and client-side TLS.
2202 tls_close(BOOL is_server, BOOL shutdown)
2204 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2205 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2207 if (*fdp < 0) return; /* TLS was not active */
2211 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2212 SSL_shutdown(*sslp);
2224 /*************************************************
2225 * Let tls_require_ciphers be checked at startup *
2226 *************************************************/
2228 /* The tls_require_ciphers option, if set, must be something which the
2231 Returns: NULL on success, or error message
2235 tls_validate_require_cipher(void)
2238 uschar *s, *expciphers, *err;
2240 /* this duplicates from tls_init(), we need a better "init just global
2241 state, for no specific purpose" singleton function of our own */
2243 SSL_load_error_strings();
2244 OpenSSL_add_ssl_algorithms();
2245 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2246 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2247 list of available digests. */
2248 EVP_add_digest(EVP_sha256());
2251 if (!(tls_require_ciphers && *tls_require_ciphers))
2254 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2255 return US"failed to expand tls_require_ciphers";
2257 if (!(expciphers && *expciphers))
2260 /* normalisation ripped from above */
2262 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2266 ctx = SSL_CTX_new(SSLv23_server_method());
2269 ERR_error_string(ERR_get_error(), ssl_errstring);
2270 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2274 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2276 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2278 ERR_error_string(ERR_get_error(), ssl_errstring);
2279 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2290 /*************************************************
2291 * Report the library versions. *
2292 *************************************************/
2294 /* There have historically been some issues with binary compatibility in
2295 OpenSSL libraries; if Exim (like many other applications) is built against
2296 one version of OpenSSL but the run-time linker picks up another version,
2297 it can result in serious failures, including crashing with a SIGSEGV. So
2298 report the version found by the compiler and the run-time version.
2300 Note: some OS vendors backport security fixes without changing the version
2301 number/string, and the version date remains unchanged. The _build_ date
2302 will change, so we can more usefully assist with version diagnosis by also
2303 reporting the build date.
2305 Arguments: a FILE* to print the results to
2310 tls_version_report(FILE *f)
2312 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2315 OPENSSL_VERSION_TEXT,
2316 SSLeay_version(SSLEAY_VERSION),
2317 SSLeay_version(SSLEAY_BUILT_ON));
2318 /* third line is 38 characters for the %s and the line is 73 chars long;
2319 the OpenSSL output includes a "built on: " prefix already. */
2325 /*************************************************
2326 * Random number generation *
2327 *************************************************/
2329 /* Pseudo-random number generation. The result is not expected to be
2330 cryptographically strong but not so weak that someone will shoot themselves
2331 in the foot using it as a nonce in input in some email header scheme or
2332 whatever weirdness they'll twist this into. The result should handle fork()
2333 and avoid repeating sequences. OpenSSL handles that for us.
2337 Returns a random number in range [0, max-1]
2341 vaguely_random_number(int max)
2345 static pid_t pidlast = 0;
2348 uschar smallbuf[sizeof(r)];
2354 if (pidnow != pidlast)
2356 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2357 is unique for each thread", this doesn't apparently apply across processes,
2358 so our own warning from vaguely_random_number_fallback() applies here too.
2359 Fix per PostgreSQL. */
2365 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2369 gettimeofday(&r.tv, NULL);
2372 RAND_seed((uschar *)(&r), sizeof(r));
2374 /* We're after pseudo-random, not random; if we still don't have enough data
2375 in the internal PRNG then our options are limited. We could sleep and hope
2376 for entropy to come along (prayer technique) but if the system is so depleted
2377 in the first place then something is likely to just keep taking it. Instead,
2378 we'll just take whatever little bit of pseudo-random we can still manage to
2381 needed_len = sizeof(r);
2382 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2383 asked for a number less than 10. */
2384 for (r = max, i = 0; r; ++i)
2390 /* We do not care if crypto-strong */
2391 i = RAND_pseudo_bytes(smallbuf, needed_len);
2395 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2396 return vaguely_random_number_fallback(max);
2400 for (p = smallbuf; needed_len; --needed_len, ++p)
2406 /* We don't particularly care about weighted results; if someone wants
2407 smooth distribution and cares enough then they should submit a patch then. */
2414 /*************************************************
2415 * OpenSSL option parse *
2416 *************************************************/
2418 /* Parse one option for tls_openssl_options_parse below
2421 name one option name
2422 value place to store a value for it
2423 Returns success or failure in parsing
2426 struct exim_openssl_option {
2430 /* We could use a macro to expand, but we need the ifdef and not all the
2431 options document which version they were introduced in. Policylet: include
2432 all options unless explicitly for DTLS, let the administrator choose which
2435 This list is current as of:
2437 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2439 static struct exim_openssl_option exim_openssl_options[] = {
2440 /* KEEP SORTED ALPHABETICALLY! */
2442 { US"all", SSL_OP_ALL },
2444 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2445 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2447 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2448 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2450 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2451 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2453 #ifdef SSL_OP_EPHEMERAL_RSA
2454 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2456 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2457 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2459 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2460 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2462 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2463 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2465 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2466 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2468 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2469 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2471 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2472 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2474 #ifdef SSL_OP_NO_COMPRESSION
2475 { US"no_compression", SSL_OP_NO_COMPRESSION },
2477 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2478 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2480 #ifdef SSL_OP_NO_SSLv2
2481 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2483 #ifdef SSL_OP_NO_SSLv3
2484 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2486 #ifdef SSL_OP_NO_TICKET
2487 { US"no_ticket", SSL_OP_NO_TICKET },
2489 #ifdef SSL_OP_NO_TLSv1
2490 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2492 #ifdef SSL_OP_NO_TLSv1_1
2493 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2494 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2495 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2497 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2500 #ifdef SSL_OP_NO_TLSv1_2
2501 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2503 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2504 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2506 #ifdef SSL_OP_SINGLE_DH_USE
2507 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2509 #ifdef SSL_OP_SINGLE_ECDH_USE
2510 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2512 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2513 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2515 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2516 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2518 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2519 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2521 #ifdef SSL_OP_TLS_D5_BUG
2522 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2524 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2525 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2528 static int exim_openssl_options_size =
2529 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2533 tls_openssl_one_option_parse(uschar *name, long *value)
2536 int last = exim_openssl_options_size;
2537 while (last > first)
2539 int middle = (first + last)/2;
2540 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2543 *value = exim_openssl_options[middle].value;
2557 /*************************************************
2558 * OpenSSL option parsing logic *
2559 *************************************************/
2561 /* OpenSSL has a number of compatibility options which an administrator might
2562 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2563 we look like log_selector.
2566 option_spec the administrator-supplied string of options
2567 results ptr to long storage for the options bitmap
2568 Returns success or failure
2572 tls_openssl_options_parse(uschar *option_spec, long *results)
2577 BOOL adding, item_parsed;
2580 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2581 * from default because it increases BEAST susceptibility. */
2582 #ifdef SSL_OP_NO_SSLv2
2583 result |= SSL_OP_NO_SSLv2;
2586 if (option_spec == NULL)
2592 for (s=option_spec; *s != '\0'; /**/)
2594 while (isspace(*s)) ++s;
2597 if (*s != '+' && *s != '-')
2599 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2600 "+ or - expected but found \"%s\"\n", s);
2603 adding = *s++ == '+';
2604 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2607 item_parsed = tls_openssl_one_option_parse(s, &item);
2610 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2613 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2614 adding ? "adding" : "removing", result, item, s);
2629 /* End of tls-openssl.c */