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 txt[sizeof(name)-1] = '\0';
249 debug_printf(" %s\n", name);
257 /*************************************************
258 * Callback for verification *
259 *************************************************/
261 /* The SSL library does certificate verification if set up to do so. This
262 callback has the current yes/no state is in "state". If verification succeeded,
263 we set up the tls_peerdn string. If verification failed, what happens depends
264 on whether the client is required to present a verifiable certificate or not.
266 If verification is optional, we change the state to yes, but still log the
267 verification error. For some reason (it really would help to have proper
268 documentation of OpenSSL), this callback function then gets called again, this
269 time with state = 1. In fact, that's useful, because we can set up the peerdn
270 value, but we must take care not to set the private verified flag on the second
273 Note: this function is not called if the client fails to present a certificate
274 when asked. We get here only if a certificate has been received. Handling of
275 optional verification for this case is done when requesting SSL to verify, by
276 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
278 May be called multiple times for different issues with a certificate, even
279 for a given "depth" in the certificate chain.
282 state current yes/no state as 1/0
283 x509ctx certificate information.
284 client TRUE for client startup, FALSE for server startup
286 Returns: 1 if verified, 0 if not
290 verify_callback(int state, X509_STORE_CTX *x509ctx,
291 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
293 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
294 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
295 static uschar txt[256];
296 #ifdef EXPERIMENTAL_EVENT
301 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
302 txt[sizeof(txt)-1] = '\0';
306 log_write(0, LOG_MAIN, "[%s] SSL verify error: depth=%d error=%s cert=%s",
307 tlsp == &tls_out ? deliver_host_address : sender_host_address,
309 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
314 tlsp->peercert = X509_dup(cert);
315 return 0; /* reject */
317 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
318 "tls_try_verify_hosts)\n");
323 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
325 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
326 { /* client, wanting stapling */
327 /* Add the server cert's signing chain as the one
328 for the verification of the OCSP stapled information. */
330 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
335 #ifdef EXPERIMENTAL_EVENT
336 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
339 tlsp->peercert = X509_dup(cert);
340 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
342 log_write(0, LOG_MAIN, "[%s] SSL verify denied by event-action: "
343 "depth=%d cert=%s: %s",
344 tlsp == &tls_out ? deliver_host_address : sender_host_address,
348 return 0; /* reject */
349 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
350 "(host in tls_try_verify_hosts)\n");
352 X509_free(tlsp->peercert);
353 tlsp->peercert = NULL;
359 const uschar * verify_cert_hostnames;
362 tlsp->peercert = X509_dup(cert);
364 if ( tlsp == &tls_out
365 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
366 /* client, wanting hostname check */
368 # if EXIM_HAVE_OPENSSL_CHECKHOST
369 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
370 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
372 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
373 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
377 const uschar * list = verify_cert_hostnames;
380 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
381 if ((rc = X509_check_host(cert, name, 0,
382 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
383 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS)))
387 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error\n",
388 tlsp == &tls_out ? deliver_host_address : sender_host_address);
395 log_write(0, LOG_MAIN,
396 "[%s] SSL verify error: certificate name mismatch: \"%s\"\n",
397 tlsp == &tls_out ? deliver_host_address : sender_host_address,
401 return 0; /* reject */
402 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
403 "tls_try_verify_hosts)\n");
407 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
409 log_write(0, LOG_MAIN,
410 "[%s] SSL verify error: certificate name mismatch: \"%s\"\n",
411 tlsp == &tls_out ? deliver_host_address : sender_host_address,
415 return 0; /* reject */
416 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
417 "tls_try_verify_hosts)\n");
421 #ifdef EXPERIMENTAL_EVENT
422 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
424 if ((yield = event_raise(ev, US"tls:cert", US"0")))
426 log_write(0, LOG_MAIN, "[%s] SSL verify denied by event-action: "
427 "depth=0 cert=%s: %s",
428 tlsp == &tls_out ? deliver_host_address : sender_host_address,
432 return 0; /* reject */
433 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
434 "(host in tls_try_verify_hosts)\n");
438 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
439 *calledp ? "" : " authenticated", txt);
440 if (!*calledp) tlsp->certificate_verified = TRUE;
444 return 1; /* accept, at least for this level */
448 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
450 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
454 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
456 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
460 #ifdef EXPERIMENTAL_DANE
462 /* This gets called *by* the dane library verify callback, which interposes
466 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
468 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
469 static uschar txt[256];
470 #ifdef EXPERIMENTAL_EVENT
471 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
475 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
476 txt[sizeof(txt)-1] = '\0';
478 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
479 tls_out.peerdn = txt;
480 tls_out.peercert = X509_dup(cert);
482 #ifdef EXPERIMENTAL_EVENT
483 if (client_static_cbinfo->event_action)
485 if ((yield = event_raise(client_static_cbinfo->event_action,
486 US"tls:cert", string_sprintf("%d", depth))))
488 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
489 "depth=%d cert=%s: %s", depth, txt, yield);
490 tls_out.certificate_verified = FALSE;
491 return 0; /* reject */
495 X509_free(tls_out.peercert);
496 tls_out.peercert = NULL;
502 tls_out.dane_verified =
503 tls_out.certificate_verified = TRUE;
507 #endif /*EXPERIMENTAL_DANE*/
510 /*************************************************
511 * Information callback *
512 *************************************************/
514 /* The SSL library functions call this from time to time to indicate what they
515 are doing. We copy the string to the debugging output when TLS debugging has
527 info_callback(SSL *s, int where, int ret)
531 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
536 /*************************************************
537 * Initialize for DH *
538 *************************************************/
540 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
543 dhparam DH parameter file or fixed parameter identity string
544 host connected host, if client; NULL if server
546 Returns: TRUE if OK (nothing to set up, or setup worked)
550 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host)
557 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
560 if (!dhexpanded || !*dhexpanded)
561 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
562 else if (dhexpanded[0] == '/')
564 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
566 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
567 host, US strerror(errno));
573 if (Ustrcmp(dhexpanded, "none") == 0)
575 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
579 if (!(pem = std_dh_prime_named(dhexpanded)))
581 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
582 host, US strerror(errno));
585 bio = BIO_new_mem_buf(CS pem, -1);
588 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
591 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
596 /* Even if it is larger, we silently return success rather than cause things
597 * to fail out, so that a too-large DH will not knock out all TLS; it's a
598 * debatable choice. */
599 if ((8*DH_size(dh)) > tls_dh_max_bits)
602 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
603 8*DH_size(dh), tls_dh_max_bits);
607 SSL_CTX_set_tmp_dh(sctx, dh);
609 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
610 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
623 /*************************************************
624 * Load OCSP information into state *
625 *************************************************/
627 /* Called to load the server OCSP response from the given file into memory, once
628 caller has determined this is needed. Checks validity. Debugs a message
631 ASSUMES: single response, for single cert.
634 sctx the SSL_CTX* to update
635 cbinfo various parts of session state
636 expanded the filename putatively holding an OCSP response
641 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
645 OCSP_BASICRESP *basic_response;
646 OCSP_SINGLERESP *single_response;
647 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
649 unsigned long verify_flags;
650 int status, reason, i;
652 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
653 if (cbinfo->u_ocsp.server.response)
655 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
656 cbinfo->u_ocsp.server.response = NULL;
659 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
662 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
663 cbinfo->u_ocsp.server.file_expanded);
667 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
671 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
675 status = OCSP_response_status(resp);
676 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
678 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
679 OCSP_response_status_str(status), status);
683 basic_response = OCSP_response_get1_basic(resp);
687 debug_printf("OCSP response parse error: unable to extract basic response.\n");
691 store = SSL_CTX_get_cert_store(sctx);
692 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
694 /* May need to expose ability to adjust those flags?
695 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
696 OCSP_TRUSTOTHER OCSP_NOINTERN */
698 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
702 ERR_error_string(ERR_get_error(), ssl_errstring);
703 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
708 /* Here's the simplifying assumption: there's only one response, for the
709 one certificate we use, and nothing for anything else in a chain. If this
710 proves false, we need to extract a cert id from our issued cert
711 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
712 right cert in the stack and then calls OCSP_single_get0_status()).
714 I'm hoping to avoid reworking a bunch more of how we handle state here. */
715 single_response = OCSP_resp_get0(basic_response, 0);
716 if (!single_response)
719 debug_printf("Unable to get first response from OCSP basic response.\n");
723 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
724 if (status != V_OCSP_CERTSTATUS_GOOD)
726 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
727 OCSP_cert_status_str(status), status,
728 OCSP_crl_reason_str(reason), reason);
732 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
734 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
739 cbinfo->u_ocsp.server.response = resp;
743 if (running_in_test_harness)
745 extern char ** environ;
747 for (p = USS environ; *p != NULL; p++)
748 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
750 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
751 goto supply_response;
756 #endif /*!DISABLE_OCSP*/
761 /*************************************************
762 * Expand key and cert file specs *
763 *************************************************/
765 /* Called once during tls_init and possibly again during TLS setup, for a
766 new context, if Server Name Indication was used and tls_sni was seen in
767 the certificate string.
770 sctx the SSL_CTX* to update
771 cbinfo various parts of session state
773 Returns: OK/DEFER/FAIL
777 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
781 if (cbinfo->certificate == NULL)
784 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
785 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
786 Ustrstr(cbinfo->certificate, US"tls_out_sni")
788 reexpand_tls_files_for_sni = TRUE;
790 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
793 if (expanded != NULL)
795 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
796 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
797 return tls_error(string_sprintf(
798 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
802 if (cbinfo->privatekey != NULL &&
803 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
806 /* If expansion was forced to fail, key_expanded will be NULL. If the result
807 of the expansion is an empty string, ignore it also, and assume the private
808 key is in the same file as the certificate. */
810 if (expanded != NULL && *expanded != 0)
812 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
813 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
814 return tls_error(string_sprintf(
815 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
819 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
821 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
824 if (expanded != NULL && *expanded != 0)
826 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
827 if (cbinfo->u_ocsp.server.file_expanded &&
828 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
831 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
833 ocsp_load_response(sctx, cbinfo, expanded);
845 /*************************************************
846 * Callback to handle SNI *
847 *************************************************/
849 /* Called when acting as server during the TLS session setup if a Server Name
850 Indication extension was sent by the client.
852 API documentation is OpenSSL s_server.c implementation.
855 s SSL* of the current session
856 ad unknown (part of OpenSSL API) (unused)
857 arg Callback of "our" registered data
859 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
862 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
864 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
866 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
867 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
869 int old_pool = store_pool;
872 return SSL_TLSEXT_ERR_OK;
874 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
875 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
877 /* Make the extension value available for expansion */
878 store_pool = POOL_PERM;
879 tls_in.sni = string_copy(US servername);
880 store_pool = old_pool;
882 if (!reexpand_tls_files_for_sni)
883 return SSL_TLSEXT_ERR_OK;
885 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
886 not confident that memcpy wouldn't break some internal reference counting.
887 Especially since there's a references struct member, which would be off. */
889 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
891 ERR_error_string(ERR_get_error(), ssl_errstring);
892 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
893 return SSL_TLSEXT_ERR_NOACK;
896 /* Not sure how many of these are actually needed, since SSL object
897 already exists. Might even need this selfsame callback, for reneg? */
899 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
900 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
901 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
902 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
903 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
904 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
905 if (cbinfo->server_cipher_list)
906 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
908 if (cbinfo->u_ocsp.server.file)
910 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
911 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
915 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
916 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
918 /* do this after setup_certs, because this can require the certs for verifying
920 rc = tls_expand_session_files(server_sni, cbinfo);
921 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
923 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
924 return SSL_TLSEXT_ERR_NOACK;
926 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
927 SSL_set_SSL_CTX(s, server_sni);
929 return SSL_TLSEXT_ERR_OK;
931 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
938 /*************************************************
939 * Callback to handle OCSP Stapling *
940 *************************************************/
942 /* Called when acting as server during the TLS session setup if the client
943 requests OCSP information with a Certificate Status Request.
945 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
951 tls_server_stapling_cb(SSL *s, void *arg)
953 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
954 uschar *response_der;
955 int response_der_len;
958 debug_printf("Received TLS status request (OCSP stapling); %s response.",
959 cbinfo->u_ocsp.server.response ? "have" : "lack");
961 tls_in.ocsp = OCSP_NOT_RESP;
962 if (!cbinfo->u_ocsp.server.response)
963 return SSL_TLSEXT_ERR_NOACK;
966 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
968 if (response_der_len <= 0)
969 return SSL_TLSEXT_ERR_NOACK;
971 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
972 tls_in.ocsp = OCSP_VFIED;
973 return SSL_TLSEXT_ERR_OK;
978 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
980 BIO_printf(bp, "\t%s: ", str);
981 ASN1_GENERALIZEDTIME_print(bp, time);
986 tls_client_stapling_cb(SSL *s, void *arg)
988 tls_ext_ctx_cb * cbinfo = arg;
989 const unsigned char * p;
995 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
996 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
999 /* Expect this when we requested ocsp but got none */
1000 if ( cbinfo->u_ocsp.client.verify_required
1001 && log_extra_selector & LX_tls_cipher)
1002 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1004 DEBUG(D_tls) debug_printf(" null\n");
1005 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1008 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1010 tls_out.ocsp = OCSP_FAILED;
1011 if (log_extra_selector & LX_tls_cipher)
1012 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1014 DEBUG(D_tls) debug_printf(" parse error\n");
1018 if(!(bs = OCSP_response_get1_basic(rsp)))
1020 tls_out.ocsp = OCSP_FAILED;
1021 if (log_extra_selector & LX_tls_cipher)
1022 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1024 DEBUG(D_tls) debug_printf(" error parsing response\n");
1025 OCSP_RESPONSE_free(rsp);
1029 /* We'd check the nonce here if we'd put one in the request. */
1030 /* However that would defeat cacheability on the server so we don't. */
1032 /* This section of code reworked from OpenSSL apps source;
1033 The OpenSSL Project retains copyright:
1034 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1039 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1041 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1043 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1045 /* Use the chain that verified the server cert to verify the stapled info */
1046 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1048 if ((i = OCSP_basic_verify(bs, NULL,
1049 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1051 tls_out.ocsp = OCSP_FAILED;
1052 if (log_extra_selector & LX_tls_cipher)
1053 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1054 BIO_printf(bp, "OCSP response verify failure\n");
1055 ERR_print_errors(bp);
1056 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1060 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1063 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1064 OCSP_SINGLERESP * single;
1066 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1068 tls_out.ocsp = OCSP_FAILED;
1069 log_write(0, LOG_MAIN, "OCSP stapling "
1070 "with multiple responses not handled");
1071 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1074 single = OCSP_resp_get0(bs, 0);
1075 status = OCSP_single_get0_status(single, &reason, &rev,
1076 &thisupd, &nextupd);
1079 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1080 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1081 if (!OCSP_check_validity(thisupd, nextupd,
1082 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1084 tls_out.ocsp = OCSP_FAILED;
1085 DEBUG(D_tls) ERR_print_errors(bp);
1086 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1087 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1091 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1092 OCSP_cert_status_str(status));
1095 case V_OCSP_CERTSTATUS_GOOD:
1096 tls_out.ocsp = OCSP_VFIED;
1099 case V_OCSP_CERTSTATUS_REVOKED:
1100 tls_out.ocsp = OCSP_FAILED;
1101 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1102 reason != -1 ? "; reason: " : "",
1103 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1104 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1105 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1108 tls_out.ocsp = OCSP_FAILED;
1109 log_write(0, LOG_MAIN,
1110 "Server certificate status unknown, in OCSP stapling");
1111 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1119 OCSP_RESPONSE_free(rsp);
1122 #endif /*!DISABLE_OCSP*/
1125 /*************************************************
1126 * Initialize for TLS *
1127 *************************************************/
1129 /* Called from both server and client code, to do preliminary initialization
1130 of the library. We allocate and return a context structure.
1133 ctxp returned SSL context
1134 host connected host, if client; NULL if server
1135 dhparam DH parameter file
1136 certificate certificate file
1137 privatekey private key
1138 ocsp_file file of stapling info (server); flag for require ocsp (client)
1139 addr address if client; NULL if server (for some randomness)
1140 cbp place to put allocated callback context
1142 Returns: OK/DEFER/FAIL
1146 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1148 #ifndef DISABLE_OCSP
1151 address_item *addr, tls_ext_ctx_cb ** cbp)
1156 tls_ext_ctx_cb * cbinfo;
1158 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1159 cbinfo->certificate = certificate;
1160 cbinfo->privatekey = privatekey;
1161 #ifndef DISABLE_OCSP
1162 if ((cbinfo->is_server = host==NULL))
1164 cbinfo->u_ocsp.server.file = ocsp_file;
1165 cbinfo->u_ocsp.server.file_expanded = NULL;
1166 cbinfo->u_ocsp.server.response = NULL;
1169 cbinfo->u_ocsp.client.verify_store = NULL;
1171 cbinfo->dhparam = dhparam;
1172 cbinfo->server_cipher_list = NULL;
1173 cbinfo->host = host;
1174 #ifdef EXPERIMENTAL_EVENT
1175 cbinfo->event_action = NULL;
1178 SSL_load_error_strings(); /* basic set up */
1179 OpenSSL_add_ssl_algorithms();
1181 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1182 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1183 list of available digests. */
1184 EVP_add_digest(EVP_sha256());
1187 /* Create a context.
1188 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1189 negotiation in the different methods; as far as I can tell, the only
1190 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1191 when OpenSSL is built without SSLv2 support.
1192 By disabling with openssl_options, we can let admins re-enable with the
1195 *ctxp = SSL_CTX_new((host == NULL)?
1196 SSLv23_server_method() : SSLv23_client_method());
1198 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1200 /* It turns out that we need to seed the random number generator this early in
1201 order to get the full complement of ciphers to work. It took me roughly a day
1202 of work to discover this by experiment.
1204 On systems that have /dev/urandom, SSL may automatically seed itself from
1205 there. Otherwise, we have to make something up as best we can. Double check
1211 gettimeofday(&r.tv, NULL);
1214 RAND_seed((uschar *)(&r), sizeof(r));
1215 RAND_seed((uschar *)big_buffer, big_buffer_size);
1216 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1219 return tls_error(US"RAND_status", host,
1220 US"unable to seed random number generator");
1223 /* Set up the information callback, which outputs if debugging is at a suitable
1226 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1228 /* Automatically re-try reads/writes after renegotiation. */
1229 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1231 /* Apply administrator-supplied work-arounds.
1232 Historically we applied just one requested option,
1233 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1234 moved to an administrator-controlled list of options to specify and
1235 grandfathered in the first one as the default value for "openssl_options".
1237 No OpenSSL version number checks: the options we accept depend upon the
1238 availability of the option value macros from OpenSSL. */
1240 okay = tls_openssl_options_parse(openssl_options, &init_options);
1242 return tls_error(US"openssl_options parsing failed", host, NULL);
1246 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1247 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1248 return tls_error(string_sprintf(
1249 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1252 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1254 /* Initialize with DH parameters if supplied */
1256 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1258 /* Set up certificate and key (and perhaps OCSP info) */
1260 rc = tls_expand_session_files(*ctxp, cbinfo);
1261 if (rc != OK) return rc;
1263 /* If we need to handle SNI, do so */
1264 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1265 if (host == NULL) /* server */
1267 # ifndef DISABLE_OCSP
1268 /* We check u_ocsp.server.file, not server.response, because we care about if
1269 the option exists, not what the current expansion might be, as SNI might
1270 change the certificate and OCSP file in use between now and the time the
1271 callback is invoked. */
1272 if (cbinfo->u_ocsp.server.file)
1274 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1275 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1278 /* We always do this, so that $tls_sni is available even if not used in
1280 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1281 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1283 # ifndef DISABLE_OCSP
1285 if(ocsp_file) /* wanting stapling */
1287 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1289 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1292 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1293 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1298 cbinfo->verify_cert_hostnames = NULL;
1300 /* Set up the RSA callback */
1302 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1304 /* Finally, set the timeout, and we are done */
1306 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1307 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1317 /*************************************************
1318 * Get name of cipher in use *
1319 *************************************************/
1322 Argument: pointer to an SSL structure for the connection
1323 buffer to use for answer
1325 pointer to number of bits for cipher
1330 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1332 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1333 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1334 the accessor functions use const in the prototype. */
1335 const SSL_CIPHER *c;
1338 ver = (const uschar *)SSL_get_version(ssl);
1340 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1341 SSL_CIPHER_get_bits(c, bits);
1343 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1344 SSL_CIPHER_get_name(c), *bits);
1346 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1353 /*************************************************
1354 * Set up for verifying certificates *
1355 *************************************************/
1357 /* Called by both client and server startup
1360 sctx SSL_CTX* to initialise
1361 certs certs file or NULL
1362 crl CRL file or NULL
1363 host NULL in a server; the remote host in a client
1364 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1365 otherwise passed as FALSE
1366 cert_vfy_cb Callback function for certificate verification
1368 Returns: OK/DEFER/FAIL
1372 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1373 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1375 uschar *expcerts, *expcrl;
1377 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1380 if (expcerts != NULL && *expcerts != '\0')
1382 if (Ustrcmp(expcerts, "system") == 0)
1384 /* Tell the library to use its compiled-in location for the system default
1387 if (!SSL_CTX_set_default_verify_paths(sctx))
1388 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1392 struct stat statbuf;
1394 /* Tell the library to use its compiled-in location for the system default
1395 CA bundle. Those given by the exim config are additional to these */
1397 if (!SSL_CTX_set_default_verify_paths(sctx))
1398 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1400 if (Ustat(expcerts, &statbuf) < 0)
1402 log_write(0, LOG_MAIN|LOG_PANIC,
1403 "failed to stat %s for certificates", expcerts);
1409 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1410 { file = NULL; dir = expcerts; }
1412 { file = expcerts; dir = NULL; }
1414 /* If a certificate file is empty, the next function fails with an
1415 unhelpful error message. If we skip it, we get the correct behaviour (no
1416 certificates are recognized, but the error message is still misleading (it
1417 says no certificate was supplied.) But this is better. */
1419 if ((file == NULL || statbuf.st_size > 0) &&
1420 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1421 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1423 /* Load the list of CAs for which we will accept certs, for sending
1424 to the client. This is only for the one-file tls_verify_certificates
1426 If a list isn't loaded into the server, but
1427 some verify locations are set, the server end appears to make
1428 a wildcard reqest for client certs.
1429 Meanwhile, the client library as deafult behaviour *ignores* the list
1430 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1431 Because of this, and that the dir variant is likely only used for
1432 the public-CA bundle (not for a private CA), not worth fixing.
1436 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1437 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1438 sk_X509_NAME_num(names));
1439 SSL_CTX_set_client_CA_list(sctx, names);
1444 /* Handle a certificate revocation list. */
1446 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1448 /* This bit of code is now the version supplied by Lars Mainka. (I have
1449 * merely reformatted it into the Exim code style.)
1451 * "From here I changed the code to add support for multiple crl's
1452 * in pem format in one file or to support hashed directory entries in
1453 * pem format instead of a file. This method now uses the library function
1454 * X509_STORE_load_locations to add the CRL location to the SSL context.
1455 * OpenSSL will then handle the verify against CA certs and CRLs by
1456 * itself in the verify callback." */
1458 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1459 if (expcrl != NULL && *expcrl != 0)
1461 struct stat statbufcrl;
1462 if (Ustat(expcrl, &statbufcrl) < 0)
1464 log_write(0, LOG_MAIN|LOG_PANIC,
1465 "failed to stat %s for certificates revocation lists", expcrl);
1470 /* is it a file or directory? */
1472 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1473 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1477 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1483 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1485 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1486 return tls_error(US"X509_STORE_load_locations", host, NULL);
1488 /* setting the flags to check against the complete crl chain */
1490 X509_STORE_set_flags(cvstore,
1491 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1495 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1497 /* If verification is optional, don't fail if no certificate */
1499 SSL_CTX_set_verify(sctx,
1500 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1509 /*************************************************
1510 * Start a TLS session in a server *
1511 *************************************************/
1513 /* This is called when Exim is running as a server, after having received
1514 the STARTTLS command. It must respond to that command, and then negotiate
1518 require_ciphers allowed ciphers
1520 Returns: OK on success
1521 DEFER for errors before the start of the negotiation
1522 FAIL for errors during the negotation; the server can't
1527 tls_server_start(const uschar *require_ciphers)
1531 tls_ext_ctx_cb *cbinfo;
1532 static uschar cipherbuf[256];
1534 /* Check for previous activation */
1536 if (tls_in.active >= 0)
1538 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1539 smtp_printf("554 Already in TLS\r\n");
1543 /* Initialize the SSL library. If it fails, it will already have logged
1546 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1547 #ifndef DISABLE_OCSP
1550 NULL, &server_static_cbinfo);
1551 if (rc != OK) return rc;
1552 cbinfo = server_static_cbinfo;
1554 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1557 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1558 were historically separated by underscores. So that I can use either form in my
1559 tests, and also for general convenience, we turn underscores into hyphens here.
1562 if (expciphers != NULL)
1564 uschar *s = expciphers;
1565 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1566 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1567 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1568 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1569 cbinfo->server_cipher_list = expciphers;
1572 /* If this is a host for which certificate verification is mandatory or
1573 optional, set up appropriately. */
1575 tls_in.certificate_verified = FALSE;
1576 #ifdef EXPERIMENTAL_DANE
1577 tls_in.dane_verified = FALSE;
1579 server_verify_callback_called = FALSE;
1581 if (verify_check_host(&tls_verify_hosts) == OK)
1583 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1584 FALSE, verify_callback_server);
1585 if (rc != OK) return rc;
1586 server_verify_optional = FALSE;
1588 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1590 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1591 TRUE, verify_callback_server);
1592 if (rc != OK) return rc;
1593 server_verify_optional = TRUE;
1596 /* Prepare for new connection */
1598 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1600 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1602 * With the SSL_clear(), we get strange interoperability bugs with
1603 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1604 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1606 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1607 * session shutdown. In this case, we have a brand new object and there's no
1608 * obvious reason to immediately clear it. I'm guessing that this was
1609 * originally added because of incomplete initialisation which the clear fixed,
1610 * in some historic release.
1613 /* Set context and tell client to go ahead, except in the case of TLS startup
1614 on connection, where outputting anything now upsets the clients and tends to
1615 make them disconnect. We need to have an explicit fflush() here, to force out
1616 the response. Other smtp_printf() calls do not need it, because in non-TLS
1617 mode, the fflush() happens when smtp_getc() is called. */
1619 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1620 if (!tls_in.on_connect)
1622 smtp_printf("220 TLS go ahead\r\n");
1626 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1627 that the OpenSSL library doesn't. */
1629 SSL_set_wfd(server_ssl, fileno(smtp_out));
1630 SSL_set_rfd(server_ssl, fileno(smtp_in));
1631 SSL_set_accept_state(server_ssl);
1633 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1635 sigalrm_seen = FALSE;
1636 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1637 rc = SSL_accept(server_ssl);
1642 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1643 if (ERR_get_error() == 0)
1644 log_write(0, LOG_MAIN,
1645 "TLS client disconnected cleanly (rejected our certificate?)");
1649 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1651 /* TLS has been set up. Adjust the input functions to read via TLS,
1652 and initialize things. */
1654 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1655 tls_in.cipher = cipherbuf;
1660 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1661 debug_printf("Shared ciphers: %s\n", buf);
1664 /* Record the certificate we presented */
1666 X509 * crt = SSL_get_certificate(server_ssl);
1667 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1670 /* Only used by the server-side tls (tls_in), including tls_getc.
1671 Client-side (tls_out) reads (seem to?) go via
1672 smtp_read_response()/ip_recv().
1673 Hence no need to duplicate for _in and _out.
1675 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1676 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1677 ssl_xfer_eof = ssl_xfer_error = 0;
1679 receive_getc = tls_getc;
1680 receive_ungetc = tls_ungetc;
1681 receive_feof = tls_feof;
1682 receive_ferror = tls_ferror;
1683 receive_smtp_buffered = tls_smtp_buffered;
1685 tls_in.active = fileno(smtp_out);
1693 tls_client_basic_ctx_init(SSL_CTX * ctx,
1694 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo
1698 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1699 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1700 the specified host patterns if one of them is defined */
1702 if ( ( !ob->tls_verify_hosts
1703 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
1705 || (verify_check_given_host(&ob->tls_verify_hosts, host) == OK)
1707 client_verify_optional = FALSE;
1708 else if (verify_check_given_host(&ob->tls_try_verify_hosts, host) == OK)
1709 client_verify_optional = TRUE;
1713 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1714 ob->tls_crl, host, client_verify_optional, verify_callback_client)) != OK)
1717 if (verify_check_given_host(&ob->tls_verify_cert_hostnames, host) == OK)
1719 cbinfo->verify_cert_hostnames = host->name;
1720 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1721 cbinfo->verify_cert_hostnames);
1727 #ifdef EXPERIMENTAL_DANE
1729 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1733 const char * hostnames[2] = { CS host->name, NULL };
1736 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1737 return tls_error(US"hostnames load", host, NULL);
1739 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1741 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1742 ) if (rr->type == T_TLSA)
1744 uschar * p = rr->data;
1745 uint8_t usage, selector, mtype;
1746 const char * mdname;
1750 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1751 if (usage != 2 && usage != 3) continue;
1758 default: continue; /* Only match-types 0, 1, 2 are supported */
1759 case 0: mdname = NULL; break;
1760 case 1: mdname = "sha256"; break;
1761 case 2: mdname = "sha512"; break;
1765 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1768 case 0: /* action not taken */
1769 return tls_error(US"tlsa load", host, NULL);
1773 tls_out.tlsa_usage |= 1<<usage;
1779 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1782 #endif /*EXPERIMENTAL_DANE*/
1786 /*************************************************
1787 * Start a TLS session in a client *
1788 *************************************************/
1790 /* Called from the smtp transport after STARTTLS has been accepted.
1793 fd the fd of the connection
1794 host connected host (for messages)
1795 addr the first address
1796 tb transport (always smtp)
1797 tlsa_dnsa tlsa lookup, if DANE, else null
1799 Returns: OK on success
1800 FAIL otherwise - note that tls_error() will not give DEFER
1801 because this is not a server
1805 tls_client_start(int fd, host_item *host, address_item *addr,
1806 transport_instance *tb
1807 #ifdef EXPERIMENTAL_DANE
1808 , dns_answer * tlsa_dnsa
1812 smtp_transport_options_block * ob =
1813 (smtp_transport_options_block *)tb->options_block;
1814 static uschar txt[256];
1815 uschar * expciphers;
1818 static uschar cipherbuf[256];
1820 #ifndef DISABLE_OCSP
1821 BOOL request_ocsp = FALSE;
1822 BOOL require_ocsp = FALSE;
1825 #ifdef EXPERIMENTAL_DANE
1826 tls_out.tlsa_usage = 0;
1829 #ifndef DISABLE_OCSP
1831 # ifdef EXPERIMENTAL_DANE
1833 && ob->hosts_request_ocsp[0] == '*'
1834 && ob->hosts_request_ocsp[1] == '\0'
1837 /* Unchanged from default. Use a safer one under DANE */
1838 request_ocsp = TRUE;
1839 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1840 " {= {4}{$tls_out_tlsa_usage}} } "
1846 verify_check_given_host(&ob->hosts_require_ocsp, host) == OK))
1847 request_ocsp = TRUE;
1849 # ifdef EXPERIMENTAL_DANE
1853 verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1857 rc = tls_init(&client_ctx, host, NULL,
1858 ob->tls_certificate, ob->tls_privatekey,
1859 #ifndef DISABLE_OCSP
1860 (void *)(long)request_ocsp,
1862 addr, &client_static_cbinfo);
1863 if (rc != OK) return rc;
1865 tls_out.certificate_verified = FALSE;
1866 client_verify_callback_called = FALSE;
1868 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1872 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1873 are separated by underscores. So that I can use either form in my tests, and
1874 also for general convenience, we turn underscores into hyphens here. */
1876 if (expciphers != NULL)
1878 uschar *s = expciphers;
1879 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1880 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1881 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1882 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1885 #ifdef EXPERIMENTAL_DANE
1888 SSL_CTX_set_verify(client_ctx,
1889 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
1890 verify_callback_client_dane);
1892 if (!DANESSL_library_init())
1893 return tls_error(US"library init", host, NULL);
1894 if (DANESSL_CTX_init(client_ctx) <= 0)
1895 return tls_error(US"context init", host, NULL);
1901 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob, client_static_cbinfo))
1905 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1906 return tls_error(US"SSL_new", host, NULL);
1907 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1908 SSL_set_fd(client_ssl, fd);
1909 SSL_set_connect_state(client_ssl);
1913 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1915 if (tls_out.sni == NULL)
1917 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1919 else if (!Ustrlen(tls_out.sni))
1923 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1924 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1925 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1928 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1934 #ifdef EXPERIMENTAL_DANE
1936 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1940 #ifndef DISABLE_OCSP
1941 /* Request certificate status at connection-time. If the server
1942 does OCSP stapling we will get the callback (set in tls_init()) */
1943 # ifdef EXPERIMENTAL_DANE
1947 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1948 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1950 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1951 this means we avoid the OCSP request, we wasted the setup
1952 cost in tls_init(). */
1953 require_ocsp = verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
1954 request_ocsp = require_ocsp
1955 || verify_check_given_host(&ob->hosts_request_ocsp, host) == OK;
1962 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1963 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1964 tls_out.ocsp = OCSP_NOT_RESP;
1968 #ifdef EXPERIMENTAL_EVENT
1969 client_static_cbinfo->event_action = tb->event_action;
1972 /* There doesn't seem to be a built-in timeout on connection. */
1974 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1975 sigalrm_seen = FALSE;
1976 alarm(ob->command_timeout);
1977 rc = SSL_connect(client_ssl);
1980 #ifdef EXPERIMENTAL_DANE
1982 DANESSL_cleanup(client_ssl);
1986 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1988 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1990 /* Beware anonymous ciphers which lead to server_cert being NULL */
1991 /*XXX server_cert is never freed... use X509_free() */
1992 server_cert = SSL_get_peer_certificate (client_ssl);
1995 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1996 CS txt, sizeof(txt));
1997 txt[sizeof(txt)-1] = '\0';
1998 tls_out.peerdn = txt; /*XXX a static buffer... */
2001 tls_out.peerdn = NULL;
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 */