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);
297 static uschar txt[256];
298 #ifdef EXPERIMENTAL_EVENT
303 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
307 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
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, "SSL verify denied by event-action: "
343 "depth=%d cert=%s: %s", depth, txt, yield);
346 return 0; /* reject */
347 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
348 "(host in tls_try_verify_hosts)\n");
350 X509_free(tlsp->peercert);
351 tlsp->peercert = NULL;
357 #ifdef EXPERIMENTAL_CERTNAMES
358 uschar * verify_cert_hostnames;
362 tlsp->peercert = X509_dup(cert);
364 #ifdef EXPERIMENTAL_CERTNAMES
365 if ( tlsp == &tls_out
366 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
367 /* client, wanting hostname check */
369 # if EXIM_HAVE_OPENSSL_CHECKHOST
370 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
371 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
373 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
374 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
378 uschar * list = verify_cert_hostnames;
381 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
382 if ((rc = X509_check_host(cert, name, 0,
383 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
384 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS)))
388 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
395 log_write(0, LOG_MAIN,
396 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
399 return 0; /* reject */
400 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
401 "tls_try_verify_hosts)\n");
405 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
407 log_write(0, LOG_MAIN,
408 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
411 return 0; /* reject */
412 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
413 "tls_try_verify_hosts)\n");
416 #endif /*EXPERIMENTAL_CERTNAMES*/
418 #ifdef EXPERIMENTAL_EVENT
419 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
421 if ((yield = event_raise(ev, US"tls:cert", US"0")))
423 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
424 "depth=0 cert=%s: %s", txt, yield);
427 return 0; /* reject */
428 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
429 "(host in tls_try_verify_hosts)\n");
433 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
434 *calledp ? "" : " authenticated", txt);
435 if (!*calledp) tlsp->certificate_verified = TRUE;
439 return 1; /* accept, at least for this level */
443 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
445 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
449 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
451 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
455 #ifdef EXPERIMENTAL_DANE
457 /* This gets called *by* the dane library verify callback, which interposes
461 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
463 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
464 static uschar txt[256];
465 #ifdef EXPERIMENTAL_EVENT
466 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
470 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
472 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
473 tls_out.peerdn = txt;
474 tls_out.peercert = X509_dup(cert);
476 #ifdef EXPERIMENTAL_EVENT
477 if (client_static_cbinfo->event_action)
479 if ((yield = event_raise(client_static_cbinfo->event_action,
480 US"tls:cert", string_sprintf("%d", depth))))
482 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
483 "depth=%d cert=%s: %s", depth, txt, yield);
484 tls_out.certificate_verified = FALSE;
485 return 0; /* reject */
489 X509_free(tls_out.peercert);
490 tls_out.peercert = NULL;
496 tls_out.dane_verified =
497 tls_out.certificate_verified = TRUE;
501 #endif /*EXPERIMENTAL_DANE*/
504 /*************************************************
505 * Information callback *
506 *************************************************/
508 /* The SSL library functions call this from time to time to indicate what they
509 are doing. We copy the string to the debugging output when TLS debugging has
521 info_callback(SSL *s, int where, int ret)
525 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
530 /*************************************************
531 * Initialize for DH *
532 *************************************************/
534 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
537 dhparam DH parameter file or fixed parameter identity string
538 host connected host, if client; NULL if server
540 Returns: TRUE if OK (nothing to set up, or setup worked)
544 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
551 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
554 if (!dhexpanded || !*dhexpanded)
555 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
556 else if (dhexpanded[0] == '/')
558 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
560 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
561 host, US strerror(errno));
567 if (Ustrcmp(dhexpanded, "none") == 0)
569 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
573 if (!(pem = std_dh_prime_named(dhexpanded)))
575 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
576 host, US strerror(errno));
579 bio = BIO_new_mem_buf(CS pem, -1);
582 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
585 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
590 /* Even if it is larger, we silently return success rather than cause things
591 * to fail out, so that a too-large DH will not knock out all TLS; it's a
592 * debatable choice. */
593 if ((8*DH_size(dh)) > tls_dh_max_bits)
596 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
597 8*DH_size(dh), tls_dh_max_bits);
601 SSL_CTX_set_tmp_dh(sctx, dh);
603 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
604 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
617 /*************************************************
618 * Load OCSP information into state *
619 *************************************************/
621 /* Called to load the server OCSP response from the given file into memory, once
622 caller has determined this is needed. Checks validity. Debugs a message
625 ASSUMES: single response, for single cert.
628 sctx the SSL_CTX* to update
629 cbinfo various parts of session state
630 expanded the filename putatively holding an OCSP response
635 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
639 OCSP_BASICRESP *basic_response;
640 OCSP_SINGLERESP *single_response;
641 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
643 unsigned long verify_flags;
644 int status, reason, i;
646 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
647 if (cbinfo->u_ocsp.server.response)
649 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
650 cbinfo->u_ocsp.server.response = NULL;
653 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
656 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
657 cbinfo->u_ocsp.server.file_expanded);
661 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
665 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
669 status = OCSP_response_status(resp);
670 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
672 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
673 OCSP_response_status_str(status), status);
677 basic_response = OCSP_response_get1_basic(resp);
681 debug_printf("OCSP response parse error: unable to extract basic response.\n");
685 store = SSL_CTX_get_cert_store(sctx);
686 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
688 /* May need to expose ability to adjust those flags?
689 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
690 OCSP_TRUSTOTHER OCSP_NOINTERN */
692 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
696 ERR_error_string(ERR_get_error(), ssl_errstring);
697 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
702 /* Here's the simplifying assumption: there's only one response, for the
703 one certificate we use, and nothing for anything else in a chain. If this
704 proves false, we need to extract a cert id from our issued cert
705 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
706 right cert in the stack and then calls OCSP_single_get0_status()).
708 I'm hoping to avoid reworking a bunch more of how we handle state here. */
709 single_response = OCSP_resp_get0(basic_response, 0);
710 if (!single_response)
713 debug_printf("Unable to get first response from OCSP basic response.\n");
717 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
718 if (status != V_OCSP_CERTSTATUS_GOOD)
720 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
721 OCSP_cert_status_str(status), status,
722 OCSP_crl_reason_str(reason), reason);
726 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
728 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
733 cbinfo->u_ocsp.server.response = resp;
737 if (running_in_test_harness)
739 extern char ** environ;
741 for (p = USS environ; *p != NULL; p++)
742 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
744 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
745 goto supply_response;
750 #endif /*!DISABLE_OCSP*/
755 /*************************************************
756 * Expand key and cert file specs *
757 *************************************************/
759 /* Called once during tls_init and possibly again during TLS setup, for a
760 new context, if Server Name Indication was used and tls_sni was seen in
761 the certificate string.
764 sctx the SSL_CTX* to update
765 cbinfo various parts of session state
767 Returns: OK/DEFER/FAIL
771 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
775 if (cbinfo->certificate == NULL)
778 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
779 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
780 Ustrstr(cbinfo->certificate, US"tls_out_sni")
782 reexpand_tls_files_for_sni = TRUE;
784 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
787 if (expanded != NULL)
789 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
790 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
791 return tls_error(string_sprintf(
792 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
796 if (cbinfo->privatekey != NULL &&
797 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
800 /* If expansion was forced to fail, key_expanded will be NULL. If the result
801 of the expansion is an empty string, ignore it also, and assume the private
802 key is in the same file as the certificate. */
804 if (expanded != NULL && *expanded != 0)
806 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
807 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
808 return tls_error(string_sprintf(
809 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
813 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
815 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
818 if (expanded != NULL && *expanded != 0)
820 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
821 if (cbinfo->u_ocsp.server.file_expanded &&
822 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
825 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
827 ocsp_load_response(sctx, cbinfo, expanded);
839 /*************************************************
840 * Callback to handle SNI *
841 *************************************************/
843 /* Called when acting as server during the TLS session setup if a Server Name
844 Indication extension was sent by the client.
846 API documentation is OpenSSL s_server.c implementation.
849 s SSL* of the current session
850 ad unknown (part of OpenSSL API) (unused)
851 arg Callback of "our" registered data
853 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
856 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
858 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
860 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
861 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
863 int old_pool = store_pool;
866 return SSL_TLSEXT_ERR_OK;
868 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
869 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
871 /* Make the extension value available for expansion */
872 store_pool = POOL_PERM;
873 tls_in.sni = string_copy(US servername);
874 store_pool = old_pool;
876 if (!reexpand_tls_files_for_sni)
877 return SSL_TLSEXT_ERR_OK;
879 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
880 not confident that memcpy wouldn't break some internal reference counting.
881 Especially since there's a references struct member, which would be off. */
883 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
885 ERR_error_string(ERR_get_error(), ssl_errstring);
886 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
887 return SSL_TLSEXT_ERR_NOACK;
890 /* Not sure how many of these are actually needed, since SSL object
891 already exists. Might even need this selfsame callback, for reneg? */
893 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
894 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
895 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
896 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
897 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
898 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
899 if (cbinfo->server_cipher_list)
900 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
902 if (cbinfo->u_ocsp.server.file)
904 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
905 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
909 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
910 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
912 /* do this after setup_certs, because this can require the certs for verifying
914 rc = tls_expand_session_files(server_sni, cbinfo);
915 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
917 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
918 return SSL_TLSEXT_ERR_NOACK;
920 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
921 SSL_set_SSL_CTX(s, server_sni);
923 return SSL_TLSEXT_ERR_OK;
925 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
932 /*************************************************
933 * Callback to handle OCSP Stapling *
934 *************************************************/
936 /* Called when acting as server during the TLS session setup if the client
937 requests OCSP information with a Certificate Status Request.
939 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
945 tls_server_stapling_cb(SSL *s, void *arg)
947 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
948 uschar *response_der;
949 int response_der_len;
952 debug_printf("Received TLS status request (OCSP stapling); %s response.",
953 cbinfo->u_ocsp.server.response ? "have" : "lack");
955 tls_in.ocsp = OCSP_NOT_RESP;
956 if (!cbinfo->u_ocsp.server.response)
957 return SSL_TLSEXT_ERR_NOACK;
960 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
962 if (response_der_len <= 0)
963 return SSL_TLSEXT_ERR_NOACK;
965 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
966 tls_in.ocsp = OCSP_VFIED;
967 return SSL_TLSEXT_ERR_OK;
972 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
974 BIO_printf(bp, "\t%s: ", str);
975 ASN1_GENERALIZEDTIME_print(bp, time);
980 tls_client_stapling_cb(SSL *s, void *arg)
982 tls_ext_ctx_cb * cbinfo = arg;
983 const unsigned char * p;
989 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
990 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
993 /* Expect this when we requested ocsp but got none */
994 if ( cbinfo->u_ocsp.client.verify_required
995 && log_extra_selector & LX_tls_cipher)
996 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
998 DEBUG(D_tls) debug_printf(" null\n");
999 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1002 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1004 tls_out.ocsp = OCSP_FAILED;
1005 if (log_extra_selector & LX_tls_cipher)
1006 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1008 DEBUG(D_tls) debug_printf(" parse error\n");
1012 if(!(bs = OCSP_response_get1_basic(rsp)))
1014 tls_out.ocsp = OCSP_FAILED;
1015 if (log_extra_selector & LX_tls_cipher)
1016 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1018 DEBUG(D_tls) debug_printf(" error parsing response\n");
1019 OCSP_RESPONSE_free(rsp);
1023 /* We'd check the nonce here if we'd put one in the request. */
1024 /* However that would defeat cacheability on the server so we don't. */
1026 /* This section of code reworked from OpenSSL apps source;
1027 The OpenSSL Project retains copyright:
1028 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1033 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1035 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1037 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1039 /* Use the chain that verified the server cert to verify the stapled info */
1040 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1042 if ((i = OCSP_basic_verify(bs, NULL,
1043 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1045 tls_out.ocsp = OCSP_FAILED;
1046 if (log_extra_selector & LX_tls_cipher)
1047 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1048 BIO_printf(bp, "OCSP response verify failure\n");
1049 ERR_print_errors(bp);
1050 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1054 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1057 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1058 OCSP_SINGLERESP * single;
1060 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1062 tls_out.ocsp = OCSP_FAILED;
1063 log_write(0, LOG_MAIN, "OCSP stapling "
1064 "with multiple responses not handled");
1065 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1068 single = OCSP_resp_get0(bs, 0);
1069 status = OCSP_single_get0_status(single, &reason, &rev,
1070 &thisupd, &nextupd);
1073 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1074 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1075 if (!OCSP_check_validity(thisupd, nextupd,
1076 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1078 tls_out.ocsp = OCSP_FAILED;
1079 DEBUG(D_tls) ERR_print_errors(bp);
1080 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1081 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1085 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1086 OCSP_cert_status_str(status));
1089 case V_OCSP_CERTSTATUS_GOOD:
1090 tls_out.ocsp = OCSP_VFIED;
1093 case V_OCSP_CERTSTATUS_REVOKED:
1094 tls_out.ocsp = OCSP_FAILED;
1095 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1096 reason != -1 ? "; reason: " : "",
1097 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1098 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1099 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1102 tls_out.ocsp = OCSP_FAILED;
1103 log_write(0, LOG_MAIN,
1104 "Server certificate status unknown, in OCSP stapling");
1105 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1113 OCSP_RESPONSE_free(rsp);
1116 #endif /*!DISABLE_OCSP*/
1119 /*************************************************
1120 * Initialize for TLS *
1121 *************************************************/
1123 /* Called from both server and client code, to do preliminary initialization
1124 of the library. We allocate and return a context structure.
1127 ctxp returned SSL context
1128 host connected host, if client; NULL if server
1129 dhparam DH parameter file
1130 certificate certificate file
1131 privatekey private key
1132 ocsp_file file of stapling info (server); flag for require ocsp (client)
1133 addr address if client; NULL if server (for some randomness)
1134 cbp place to put allocated callback context
1136 Returns: OK/DEFER/FAIL
1140 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1142 #ifndef DISABLE_OCSP
1145 address_item *addr, tls_ext_ctx_cb ** cbp)
1150 tls_ext_ctx_cb * cbinfo;
1152 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1153 cbinfo->certificate = certificate;
1154 cbinfo->privatekey = privatekey;
1155 #ifndef DISABLE_OCSP
1156 if ((cbinfo->is_server = host==NULL))
1158 cbinfo->u_ocsp.server.file = ocsp_file;
1159 cbinfo->u_ocsp.server.file_expanded = NULL;
1160 cbinfo->u_ocsp.server.response = NULL;
1163 cbinfo->u_ocsp.client.verify_store = NULL;
1165 cbinfo->dhparam = dhparam;
1166 cbinfo->server_cipher_list = NULL;
1167 cbinfo->host = host;
1168 #ifdef EXPERIMENTAL_EVENT
1169 cbinfo->event_action = NULL;
1172 SSL_load_error_strings(); /* basic set up */
1173 OpenSSL_add_ssl_algorithms();
1175 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1176 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1177 list of available digests. */
1178 EVP_add_digest(EVP_sha256());
1181 /* Create a context.
1182 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1183 negotiation in the different methods; as far as I can tell, the only
1184 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1185 when OpenSSL is built without SSLv2 support.
1186 By disabling with openssl_options, we can let admins re-enable with the
1189 *ctxp = SSL_CTX_new((host == NULL)?
1190 SSLv23_server_method() : SSLv23_client_method());
1192 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1194 /* It turns out that we need to seed the random number generator this early in
1195 order to get the full complement of ciphers to work. It took me roughly a day
1196 of work to discover this by experiment.
1198 On systems that have /dev/urandom, SSL may automatically seed itself from
1199 there. Otherwise, we have to make something up as best we can. Double check
1205 gettimeofday(&r.tv, NULL);
1208 RAND_seed((uschar *)(&r), sizeof(r));
1209 RAND_seed((uschar *)big_buffer, big_buffer_size);
1210 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1213 return tls_error(US"RAND_status", host,
1214 US"unable to seed random number generator");
1217 /* Set up the information callback, which outputs if debugging is at a suitable
1220 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1222 /* Automatically re-try reads/writes after renegotiation. */
1223 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1225 /* Apply administrator-supplied work-arounds.
1226 Historically we applied just one requested option,
1227 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1228 moved to an administrator-controlled list of options to specify and
1229 grandfathered in the first one as the default value for "openssl_options".
1231 No OpenSSL version number checks: the options we accept depend upon the
1232 availability of the option value macros from OpenSSL. */
1234 okay = tls_openssl_options_parse(openssl_options, &init_options);
1236 return tls_error(US"openssl_options parsing failed", host, NULL);
1240 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1241 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1242 return tls_error(string_sprintf(
1243 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1246 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1248 /* Initialize with DH parameters if supplied */
1250 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1252 /* Set up certificate and key (and perhaps OCSP info) */
1254 rc = tls_expand_session_files(*ctxp, cbinfo);
1255 if (rc != OK) return rc;
1257 /* If we need to handle SNI, do so */
1258 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1259 if (host == NULL) /* server */
1261 # ifndef DISABLE_OCSP
1262 /* We check u_ocsp.server.file, not server.response, because we care about if
1263 the option exists, not what the current expansion might be, as SNI might
1264 change the certificate and OCSP file in use between now and the time the
1265 callback is invoked. */
1266 if (cbinfo->u_ocsp.server.file)
1268 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1269 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1272 /* We always do this, so that $tls_sni is available even if not used in
1274 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1275 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1277 # ifndef DISABLE_OCSP
1279 if(ocsp_file) /* wanting stapling */
1281 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1283 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1286 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1287 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1292 #ifdef EXPERIMENTAL_CERTNAMES
1293 cbinfo->verify_cert_hostnames = NULL;
1296 /* Set up the RSA callback */
1298 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1300 /* Finally, set the timeout, and we are done */
1302 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1303 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1313 /*************************************************
1314 * Get name of cipher in use *
1315 *************************************************/
1318 Argument: pointer to an SSL structure for the connection
1319 buffer to use for answer
1321 pointer to number of bits for cipher
1326 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1328 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1329 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1330 the accessor functions use const in the prototype. */
1331 const SSL_CIPHER *c;
1334 ver = (const uschar *)SSL_get_version(ssl);
1336 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1337 SSL_CIPHER_get_bits(c, bits);
1339 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1340 SSL_CIPHER_get_name(c), *bits);
1342 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1349 /*************************************************
1350 * Set up for verifying certificates *
1351 *************************************************/
1353 /* Called by both client and server startup
1356 sctx SSL_CTX* to initialise
1357 certs certs file or NULL
1358 crl CRL file or NULL
1359 host NULL in a server; the remote host in a client
1360 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1361 otherwise passed as FALSE
1362 cert_vfy_cb Callback function for certificate verification
1364 Returns: OK/DEFER/FAIL
1368 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1369 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1371 uschar *expcerts, *expcrl;
1373 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1376 if (expcerts != NULL && *expcerts != '\0')
1378 struct stat statbuf;
1379 if (!SSL_CTX_set_default_verify_paths(sctx))
1380 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1382 if (Ustat(expcerts, &statbuf) < 0)
1384 log_write(0, LOG_MAIN|LOG_PANIC,
1385 "failed to stat %s for certificates", expcerts);
1391 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1392 { file = NULL; dir = expcerts; }
1394 { file = expcerts; dir = NULL; }
1396 /* If a certificate file is empty, the next function fails with an
1397 unhelpful error message. If we skip it, we get the correct behaviour (no
1398 certificates are recognized, but the error message is still misleading (it
1399 says no certificate was supplied.) But this is better. */
1401 if ((file == NULL || statbuf.st_size > 0) &&
1402 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1403 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1405 /* Load the list of CAs for which we will accept certs, for sending
1406 to the client. This is only for the one-file tls_verify_certificates
1408 If a list isn't loaded into the server, but
1409 some verify locations are set, the server end appears to make
1410 a wildcard reqest for client certs.
1411 Meanwhile, the client library as deafult behaviour *ignores* the list
1412 we send over the wire - see man SSL_CTX_set_client_cert_cb.
1413 Because of this, and that the dir variant is likely only used for
1414 the public-CA bundle (not for a private CA), not worth fixing.
1418 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
1419 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
1420 sk_X509_NAME_num(names));
1421 SSL_CTX_set_client_CA_list(sctx, names);
1425 /* Handle a certificate revocation list. */
1427 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1429 /* This bit of code is now the version supplied by Lars Mainka. (I have
1430 * merely reformatted it into the Exim code style.)
1432 * "From here I changed the code to add support for multiple crl's
1433 * in pem format in one file or to support hashed directory entries in
1434 * pem format instead of a file. This method now uses the library function
1435 * X509_STORE_load_locations to add the CRL location to the SSL context.
1436 * OpenSSL will then handle the verify against CA certs and CRLs by
1437 * itself in the verify callback." */
1439 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1440 if (expcrl != NULL && *expcrl != 0)
1442 struct stat statbufcrl;
1443 if (Ustat(expcrl, &statbufcrl) < 0)
1445 log_write(0, LOG_MAIN|LOG_PANIC,
1446 "failed to stat %s for certificates revocation lists", expcrl);
1451 /* is it a file or directory? */
1453 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1454 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1458 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1464 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1466 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1467 return tls_error(US"X509_STORE_load_locations", host, NULL);
1469 /* setting the flags to check against the complete crl chain */
1471 X509_STORE_set_flags(cvstore,
1472 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1476 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1478 /* If verification is optional, don't fail if no certificate */
1480 SSL_CTX_set_verify(sctx,
1481 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1490 /*************************************************
1491 * Start a TLS session in a server *
1492 *************************************************/
1494 /* This is called when Exim is running as a server, after having received
1495 the STARTTLS command. It must respond to that command, and then negotiate
1499 require_ciphers allowed ciphers
1501 Returns: OK on success
1502 DEFER for errors before the start of the negotiation
1503 FAIL for errors during the negotation; the server can't
1508 tls_server_start(const uschar *require_ciphers)
1512 tls_ext_ctx_cb *cbinfo;
1513 static uschar cipherbuf[256];
1515 /* Check for previous activation */
1517 if (tls_in.active >= 0)
1519 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1520 smtp_printf("554 Already in TLS\r\n");
1524 /* Initialize the SSL library. If it fails, it will already have logged
1527 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1528 #ifndef DISABLE_OCSP
1531 NULL, &server_static_cbinfo);
1532 if (rc != OK) return rc;
1533 cbinfo = server_static_cbinfo;
1535 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1538 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1539 were historically separated by underscores. So that I can use either form in my
1540 tests, and also for general convenience, we turn underscores into hyphens here.
1543 if (expciphers != NULL)
1545 uschar *s = expciphers;
1546 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1547 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1548 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1549 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1550 cbinfo->server_cipher_list = expciphers;
1553 /* If this is a host for which certificate verification is mandatory or
1554 optional, set up appropriately. */
1556 tls_in.certificate_verified = FALSE;
1557 #ifdef EXPERIMENTAL_DANE
1558 tls_in.dane_verified = FALSE;
1560 server_verify_callback_called = FALSE;
1562 if (verify_check_host(&tls_verify_hosts) == OK)
1564 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1565 FALSE, verify_callback_server);
1566 if (rc != OK) return rc;
1567 server_verify_optional = FALSE;
1569 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1571 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1572 TRUE, verify_callback_server);
1573 if (rc != OK) return rc;
1574 server_verify_optional = TRUE;
1577 /* Prepare for new connection */
1579 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1581 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1583 * With the SSL_clear(), we get strange interoperability bugs with
1584 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1585 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1587 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1588 * session shutdown. In this case, we have a brand new object and there's no
1589 * obvious reason to immediately clear it. I'm guessing that this was
1590 * originally added because of incomplete initialisation which the clear fixed,
1591 * in some historic release.
1594 /* Set context and tell client to go ahead, except in the case of TLS startup
1595 on connection, where outputting anything now upsets the clients and tends to
1596 make them disconnect. We need to have an explicit fflush() here, to force out
1597 the response. Other smtp_printf() calls do not need it, because in non-TLS
1598 mode, the fflush() happens when smtp_getc() is called. */
1600 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1601 if (!tls_in.on_connect)
1603 smtp_printf("220 TLS go ahead\r\n");
1607 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1608 that the OpenSSL library doesn't. */
1610 SSL_set_wfd(server_ssl, fileno(smtp_out));
1611 SSL_set_rfd(server_ssl, fileno(smtp_in));
1612 SSL_set_accept_state(server_ssl);
1614 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1616 sigalrm_seen = FALSE;
1617 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1618 rc = SSL_accept(server_ssl);
1623 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1624 if (ERR_get_error() == 0)
1625 log_write(0, LOG_MAIN,
1626 "TLS client disconnected cleanly (rejected our certificate?)");
1630 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1632 /* TLS has been set up. Adjust the input functions to read via TLS,
1633 and initialize things. */
1635 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1636 tls_in.cipher = cipherbuf;
1641 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1642 debug_printf("Shared ciphers: %s\n", buf);
1645 /* Record the certificate we presented */
1647 X509 * crt = SSL_get_certificate(server_ssl);
1648 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1651 /* Only used by the server-side tls (tls_in), including tls_getc.
1652 Client-side (tls_out) reads (seem to?) go via
1653 smtp_read_response()/ip_recv().
1654 Hence no need to duplicate for _in and _out.
1656 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1657 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1658 ssl_xfer_eof = ssl_xfer_error = 0;
1660 receive_getc = tls_getc;
1661 receive_ungetc = tls_ungetc;
1662 receive_feof = tls_feof;
1663 receive_ferror = tls_ferror;
1664 receive_smtp_buffered = tls_smtp_buffered;
1666 tls_in.active = fileno(smtp_out);
1674 tls_client_basic_ctx_init(SSL_CTX * ctx,
1675 host_item * host, smtp_transport_options_block * ob
1676 #ifdef EXPERIMENTAL_CERTNAMES
1677 , tls_ext_ctx_cb * cbinfo
1682 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1683 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1684 the specified host patterns if one of them is defined */
1686 if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1687 (verify_check_host(&ob->tls_verify_hosts) == OK))
1689 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1690 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1692 client_verify_optional = FALSE;
1694 #ifdef EXPERIMENTAL_CERTNAMES
1695 if (verify_check_host(&ob->tls_verify_cert_hostnames) == OK)
1697 cbinfo->verify_cert_hostnames = host->name;
1698 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1699 cbinfo->verify_cert_hostnames);
1703 else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1705 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1706 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1708 client_verify_optional = TRUE;
1715 #ifdef EXPERIMENTAL_DANE
1717 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1721 const char * hostnames[2] = { CS host->name, NULL };
1724 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1725 return tls_error(US"hostnames load", host, NULL);
1727 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1729 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1730 ) if (rr->type == T_TLSA)
1732 uschar * p = rr->data;
1733 uint8_t usage, selector, mtype;
1734 const char * mdname;
1738 /* Only DANE-TA(2) and DANE-EE(3) are supported */
1739 if (usage != 2 && usage != 3) continue;
1746 default: continue; /* Only match-types 0, 1, 2 are supported */
1747 case 0: mdname = NULL; break;
1748 case 1: mdname = "sha256"; break;
1749 case 2: mdname = "sha512"; break;
1753 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1756 case 0: /* action not taken */
1757 return tls_error(US"tlsa load", host, NULL);
1761 tls_out.tlsa_usage |= 1<<usage;
1767 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
1770 #endif /*EXPERIMENTAL_DANE*/
1774 /*************************************************
1775 * Start a TLS session in a client *
1776 *************************************************/
1778 /* Called from the smtp transport after STARTTLS has been accepted.
1781 fd the fd of the connection
1782 host connected host (for messages)
1783 addr the first address
1784 tb transport (always smtp)
1785 tlsa_dnsa tlsa lookup, if DANE, else null
1787 Returns: OK on success
1788 FAIL otherwise - note that tls_error() will not give DEFER
1789 because this is not a server
1793 tls_client_start(int fd, host_item *host, address_item *addr,
1794 transport_instance *tb
1795 #ifdef EXPERIMENTAL_DANE
1796 , dns_answer * tlsa_dnsa
1800 smtp_transport_options_block * ob =
1801 (smtp_transport_options_block *)tb->options_block;
1802 static uschar txt[256];
1803 uschar * expciphers;
1806 static uschar cipherbuf[256];
1808 #ifndef DISABLE_OCSP
1809 BOOL request_ocsp = FALSE;
1810 BOOL require_ocsp = FALSE;
1813 #ifdef EXPERIMENTAL_DANE
1814 tls_out.tlsa_usage = 0;
1817 #ifndef DISABLE_OCSP
1819 # ifdef EXPERIMENTAL_DANE
1821 && ob->hosts_request_ocsp[0] == '*'
1822 && ob->hosts_request_ocsp[1] == '\0'
1825 /* Unchanged from default. Use a safer one under DANE */
1826 request_ocsp = TRUE;
1827 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1828 " {= {4}{$tls_out_tlsa_usage}} } "
1833 if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1834 NULL, host->name, host->address, NULL) == OK))
1835 request_ocsp = TRUE;
1837 # ifdef EXPERIMENTAL_DANE
1840 request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
1841 NULL, host->name, host->address, NULL) == OK;
1845 rc = tls_init(&client_ctx, host, NULL,
1846 ob->tls_certificate, ob->tls_privatekey,
1847 #ifndef DISABLE_OCSP
1848 (void *)(long)request_ocsp,
1850 addr, &client_static_cbinfo);
1851 if (rc != OK) return rc;
1853 tls_out.certificate_verified = FALSE;
1854 client_verify_callback_called = FALSE;
1856 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1860 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1861 are separated by underscores. So that I can use either form in my tests, and
1862 also for general convenience, we turn underscores into hyphens here. */
1864 if (expciphers != NULL)
1866 uschar *s = expciphers;
1867 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1868 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1869 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1870 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1873 #ifdef EXPERIMENTAL_DANE
1876 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1878 if (!DANESSL_library_init())
1879 return tls_error(US"library init", host, NULL);
1880 if (DANESSL_CTX_init(client_ctx) <= 0)
1881 return tls_error(US"context init", host, NULL);
1887 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
1888 #ifdef EXPERIMENTAL_CERTNAMES
1889 , client_static_cbinfo
1894 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1895 return tls_error(US"SSL_new", host, NULL);
1896 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1897 SSL_set_fd(client_ssl, fd);
1898 SSL_set_connect_state(client_ssl);
1902 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1904 if (tls_out.sni == NULL)
1906 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1908 else if (!Ustrlen(tls_out.sni))
1912 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1913 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1914 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1917 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1923 #ifdef EXPERIMENTAL_DANE
1925 if ((rc = dane_tlsa_load(client_ssl, host, tlsa_dnsa)) != OK)
1929 #ifndef DISABLE_OCSP
1930 /* Request certificate status at connection-time. If the server
1931 does OCSP stapling we will get the callback (set in tls_init()) */
1932 # ifdef EXPERIMENTAL_DANE
1936 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1937 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
1939 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1940 this means we avoid the OCSP request, we wasted the setup
1941 cost in tls_init(). */
1942 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1943 NULL, host->name, host->address, NULL) == OK;
1944 request_ocsp = require_ocsp ? TRUE
1945 : verify_check_this_host(&ob->hosts_request_ocsp,
1946 NULL, host->name, host->address, NULL) == OK;
1953 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1954 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1955 tls_out.ocsp = OCSP_NOT_RESP;
1959 #ifdef EXPERIMENTAL_EVENT
1960 client_static_cbinfo->event_action = tb->event_action;
1963 /* There doesn't seem to be a built-in timeout on connection. */
1965 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1966 sigalrm_seen = FALSE;
1967 alarm(ob->command_timeout);
1968 rc = SSL_connect(client_ssl);
1971 #ifdef EXPERIMENTAL_DANE
1973 DANESSL_cleanup(client_ssl);
1977 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
1979 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
1981 /* Beware anonymous ciphers which lead to server_cert being NULL */
1982 /*XXX server_cert is never freed... use X509_free() */
1983 server_cert = SSL_get_peer_certificate (client_ssl);
1986 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
1987 CS txt, sizeof(txt));
1988 tls_out.peerdn = txt; /*XXX a static buffer... */
1991 tls_out.peerdn = NULL;
1993 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
1994 tls_out.cipher = cipherbuf;
1996 /* Record the certificate we presented */
1998 X509 * crt = SSL_get_certificate(client_ssl);
1999 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2002 tls_out.active = fd;
2010 /*************************************************
2011 * TLS version of getc *
2012 *************************************************/
2014 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2015 it refills the buffer via the SSL reading function.
2018 Returns: the next character or EOF
2020 Only used by the server-side TLS.
2026 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2031 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2032 ssl_xfer_buffer, ssl_xfer_buffer_size);
2034 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2035 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2036 error = SSL_get_error(server_ssl, inbytes);
2039 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2040 closed down, not that the socket itself has been closed down. Revert to
2041 non-SSL handling. */
2043 if (error == SSL_ERROR_ZERO_RETURN)
2045 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2047 receive_getc = smtp_getc;
2048 receive_ungetc = smtp_ungetc;
2049 receive_feof = smtp_feof;
2050 receive_ferror = smtp_ferror;
2051 receive_smtp_buffered = smtp_buffered;
2053 SSL_free(server_ssl);
2057 tls_in.cipher = NULL;
2058 tls_in.peerdn = NULL;
2064 /* Handle genuine errors */
2066 else if (error == SSL_ERROR_SSL)
2068 ERR_error_string(ERR_get_error(), ssl_errstring);
2069 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2074 else if (error != SSL_ERROR_NONE)
2076 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2081 #ifndef DISABLE_DKIM
2082 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2084 ssl_xfer_buffer_hwm = inbytes;
2085 ssl_xfer_buffer_lwm = 0;
2088 /* Something in the buffer; return next uschar */
2090 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2095 /*************************************************
2096 * Read bytes from TLS channel *
2097 *************************************************/
2104 Returns: the number of bytes read
2105 -1 after a failed read
2107 Only used by the client-side TLS.
2111 tls_read(BOOL is_server, uschar *buff, size_t len)
2113 SSL *ssl = is_server ? server_ssl : client_ssl;
2117 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2118 buff, (unsigned int)len);
2120 inbytes = SSL_read(ssl, CS buff, len);
2121 error = SSL_get_error(ssl, inbytes);
2123 if (error == SSL_ERROR_ZERO_RETURN)
2125 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2128 else if (error != SSL_ERROR_NONE)
2140 /*************************************************
2141 * Write bytes down TLS channel *
2142 *************************************************/
2146 is_server channel specifier
2150 Returns: the number of bytes after a successful write,
2151 -1 after a failed write
2153 Used by both server-side and client-side TLS.
2157 tls_write(BOOL is_server, const uschar *buff, size_t len)
2162 SSL *ssl = is_server ? server_ssl : client_ssl;
2164 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2167 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2168 outbytes = SSL_write(ssl, CS buff, left);
2169 error = SSL_get_error(ssl, outbytes);
2170 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2174 ERR_error_string(ERR_get_error(), ssl_errstring);
2175 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2178 case SSL_ERROR_NONE:
2183 case SSL_ERROR_ZERO_RETURN:
2184 log_write(0, LOG_MAIN, "SSL channel closed on write");
2187 case SSL_ERROR_SYSCALL:
2188 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2189 sender_fullhost ? sender_fullhost : US"<unknown>",
2193 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2202 /*************************************************
2203 * Close down a TLS session *
2204 *************************************************/
2206 /* This is also called from within a delivery subprocess forked from the
2207 daemon, to shut down the TLS library, without actually doing a shutdown (which
2208 would tamper with the SSL session in the parent process).
2210 Arguments: TRUE if SSL_shutdown is to be called
2213 Used by both server-side and client-side TLS.
2217 tls_close(BOOL is_server, BOOL shutdown)
2219 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2220 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2222 if (*fdp < 0) return; /* TLS was not active */
2226 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2227 SSL_shutdown(*sslp);
2239 /*************************************************
2240 * Let tls_require_ciphers be checked at startup *
2241 *************************************************/
2243 /* The tls_require_ciphers option, if set, must be something which the
2246 Returns: NULL on success, or error message
2250 tls_validate_require_cipher(void)
2253 uschar *s, *expciphers, *err;
2255 /* this duplicates from tls_init(), we need a better "init just global
2256 state, for no specific purpose" singleton function of our own */
2258 SSL_load_error_strings();
2259 OpenSSL_add_ssl_algorithms();
2260 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2261 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2262 list of available digests. */
2263 EVP_add_digest(EVP_sha256());
2266 if (!(tls_require_ciphers && *tls_require_ciphers))
2269 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2270 return US"failed to expand tls_require_ciphers";
2272 if (!(expciphers && *expciphers))
2275 /* normalisation ripped from above */
2277 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2281 ctx = SSL_CTX_new(SSLv23_server_method());
2284 ERR_error_string(ERR_get_error(), ssl_errstring);
2285 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2289 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2291 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2293 ERR_error_string(ERR_get_error(), ssl_errstring);
2294 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2305 /*************************************************
2306 * Report the library versions. *
2307 *************************************************/
2309 /* There have historically been some issues with binary compatibility in
2310 OpenSSL libraries; if Exim (like many other applications) is built against
2311 one version of OpenSSL but the run-time linker picks up another version,
2312 it can result in serious failures, including crashing with a SIGSEGV. So
2313 report the version found by the compiler and the run-time version.
2315 Note: some OS vendors backport security fixes without changing the version
2316 number/string, and the version date remains unchanged. The _build_ date
2317 will change, so we can more usefully assist with version diagnosis by also
2318 reporting the build date.
2320 Arguments: a FILE* to print the results to
2325 tls_version_report(FILE *f)
2327 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2330 OPENSSL_VERSION_TEXT,
2331 SSLeay_version(SSLEAY_VERSION),
2332 SSLeay_version(SSLEAY_BUILT_ON));
2333 /* third line is 38 characters for the %s and the line is 73 chars long;
2334 the OpenSSL output includes a "built on: " prefix already. */
2340 /*************************************************
2341 * Random number generation *
2342 *************************************************/
2344 /* Pseudo-random number generation. The result is not expected to be
2345 cryptographically strong but not so weak that someone will shoot themselves
2346 in the foot using it as a nonce in input in some email header scheme or
2347 whatever weirdness they'll twist this into. The result should handle fork()
2348 and avoid repeating sequences. OpenSSL handles that for us.
2352 Returns a random number in range [0, max-1]
2356 vaguely_random_number(int max)
2360 static pid_t pidlast = 0;
2363 uschar smallbuf[sizeof(r)];
2369 if (pidnow != pidlast)
2371 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2372 is unique for each thread", this doesn't apparently apply across processes,
2373 so our own warning from vaguely_random_number_fallback() applies here too.
2374 Fix per PostgreSQL. */
2380 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2384 gettimeofday(&r.tv, NULL);
2387 RAND_seed((uschar *)(&r), sizeof(r));
2389 /* We're after pseudo-random, not random; if we still don't have enough data
2390 in the internal PRNG then our options are limited. We could sleep and hope
2391 for entropy to come along (prayer technique) but if the system is so depleted
2392 in the first place then something is likely to just keep taking it. Instead,
2393 we'll just take whatever little bit of pseudo-random we can still manage to
2396 needed_len = sizeof(r);
2397 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2398 asked for a number less than 10. */
2399 for (r = max, i = 0; r; ++i)
2405 /* We do not care if crypto-strong */
2406 i = RAND_pseudo_bytes(smallbuf, needed_len);
2410 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2411 return vaguely_random_number_fallback(max);
2415 for (p = smallbuf; needed_len; --needed_len, ++p)
2421 /* We don't particularly care about weighted results; if someone wants
2422 smooth distribution and cares enough then they should submit a patch then. */
2429 /*************************************************
2430 * OpenSSL option parse *
2431 *************************************************/
2433 /* Parse one option for tls_openssl_options_parse below
2436 name one option name
2437 value place to store a value for it
2438 Returns success or failure in parsing
2441 struct exim_openssl_option {
2445 /* We could use a macro to expand, but we need the ifdef and not all the
2446 options document which version they were introduced in. Policylet: include
2447 all options unless explicitly for DTLS, let the administrator choose which
2450 This list is current as of:
2452 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2454 static struct exim_openssl_option exim_openssl_options[] = {
2455 /* KEEP SORTED ALPHABETICALLY! */
2457 { US"all", SSL_OP_ALL },
2459 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2460 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2462 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2463 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2465 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2466 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2468 #ifdef SSL_OP_EPHEMERAL_RSA
2469 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2471 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2472 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2474 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2475 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2477 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2478 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2480 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2481 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2483 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2484 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2486 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2487 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2489 #ifdef SSL_OP_NO_COMPRESSION
2490 { US"no_compression", SSL_OP_NO_COMPRESSION },
2492 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2493 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2495 #ifdef SSL_OP_NO_SSLv2
2496 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2498 #ifdef SSL_OP_NO_SSLv3
2499 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2501 #ifdef SSL_OP_NO_TICKET
2502 { US"no_ticket", SSL_OP_NO_TICKET },
2504 #ifdef SSL_OP_NO_TLSv1
2505 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2507 #ifdef SSL_OP_NO_TLSv1_1
2508 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2509 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2510 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2512 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2515 #ifdef SSL_OP_NO_TLSv1_2
2516 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2518 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2519 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2521 #ifdef SSL_OP_SINGLE_DH_USE
2522 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2524 #ifdef SSL_OP_SINGLE_ECDH_USE
2525 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2527 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2528 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2530 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2531 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2533 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2534 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2536 #ifdef SSL_OP_TLS_D5_BUG
2537 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2539 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2540 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2543 static int exim_openssl_options_size =
2544 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2548 tls_openssl_one_option_parse(uschar *name, long *value)
2551 int last = exim_openssl_options_size;
2552 while (last > first)
2554 int middle = (first + last)/2;
2555 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2558 *value = exim_openssl_options[middle].value;
2572 /*************************************************
2573 * OpenSSL option parsing logic *
2574 *************************************************/
2576 /* OpenSSL has a number of compatibility options which an administrator might
2577 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2578 we look like log_selector.
2581 option_spec the administrator-supplied string of options
2582 results ptr to long storage for the options bitmap
2583 Returns success or failure
2587 tls_openssl_options_parse(uschar *option_spec, long *results)
2592 BOOL adding, item_parsed;
2595 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2596 * from default because it increases BEAST susceptibility. */
2597 #ifdef SSL_OP_NO_SSLv2
2598 result |= SSL_OP_NO_SSLv2;
2601 if (option_spec == NULL)
2607 for (s=option_spec; *s != '\0'; /**/)
2609 while (isspace(*s)) ++s;
2612 if (*s != '+' && *s != '-')
2614 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2615 "+ or - expected but found \"%s\"\n", s);
2618 adding = *s++ == '+';
2619 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2622 item_parsed = tls_openssl_one_option_parse(s, &item);
2625 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2628 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2629 adding ? "adding" : "removing", result, item, s);
2644 /* End of tls-openssl.c */