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
42 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
43 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
47 /* Structure for collecting random data for seeding. */
49 typedef struct randstuff {
54 /* Local static variables */
56 static BOOL client_verify_callback_called = FALSE;
57 static BOOL server_verify_callback_called = FALSE;
58 static const uschar *sid_ctx = US"exim";
60 /* We have three different contexts to care about.
62 Simple case: client, `client_ctx`
63 As a client, we can be doing a callout or cut-through delivery while receiving
64 a message. So we have a client context, which should have options initialised
65 from the SMTP Transport.
68 There are two cases: with and without ServerNameIndication from the client.
69 Given TLS SNI, we can be using different keys, certs and various other
70 configuration settings, because they're re-expanded with $tls_sni set. This
71 allows vhosting with TLS. This SNI is sent in the handshake.
72 A client might not send SNI, so we need a fallback, and an initial setup too.
73 So as a server, we start out using `server_ctx`.
74 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
75 `server_sni` from `server_ctx` and then initialise settings by re-expanding
79 static SSL_CTX *client_ctx = NULL;
80 static SSL_CTX *server_ctx = NULL;
81 static SSL *client_ssl = NULL;
82 static SSL *server_ssl = NULL;
84 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
85 static SSL_CTX *server_sni = NULL;
88 static char ssl_errstring[256];
90 static int ssl_session_timeout = 200;
91 static BOOL client_verify_optional = FALSE;
92 static BOOL server_verify_optional = FALSE;
94 static BOOL reexpand_tls_files_for_sni = FALSE;
97 typedef struct tls_ext_ctx_cb {
105 uschar *file_expanded;
106 OCSP_RESPONSE *response;
109 X509_STORE *verify_store; /* non-null if status requested */
110 BOOL verify_required;
115 /* these are cached from first expand */
116 uschar *server_cipher_list;
117 /* only passed down to tls_error: */
120 #ifdef EXPERIMENTAL_CERTNAMES
121 uschar * verify_cert_hostnames;
123 #ifdef EXPERIMENTAL_TPDA
124 uschar * event_action;
128 /* should figure out a cleanup of API to handle state preserved per
129 implementation, for various reasons, which can be void * in the APIs.
130 For now, we hack around it. */
131 tls_ext_ctx_cb *client_static_cbinfo = NULL;
132 tls_ext_ctx_cb *server_static_cbinfo = NULL;
135 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
136 int (*cert_vfy_cb)(int, X509_STORE_CTX *) );
139 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
140 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
143 static int tls_server_stapling_cb(SSL *s, void *arg);
147 /*************************************************
149 *************************************************/
151 /* Called from lots of places when errors occur before actually starting to do
152 the TLS handshake, that is, while the session is still in clear. Always returns
153 DEFER for a server and FAIL for a client so that most calls can use "return
154 tls_error(...)" to do this processing and then give an appropriate return. A
155 single function is used for both server and client, because it is called from
156 some shared functions.
159 prefix text to include in the logged error
160 host NULL if setting up a server;
161 the connected host if setting up a client
162 msg error message or NULL if we should ask OpenSSL
164 Returns: OK/DEFER/FAIL
168 tls_error(uschar *prefix, host_item *host, uschar *msg)
172 ERR_error_string(ERR_get_error(), ssl_errstring);
173 msg = (uschar *)ssl_errstring;
178 uschar *conn_info = smtp_get_connection_info();
179 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
181 log_write(0, LOG_MAIN, "TLS error on %s (%s): %s",
182 conn_info, prefix, msg);
187 log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s): %s",
188 host->name, host->address, prefix, msg);
195 /*************************************************
196 * Callback to generate RSA key *
197 *************************************************/
205 Returns: pointer to generated key
209 rsa_callback(SSL *s, int export, int keylength)
212 export = export; /* Shut picky compilers up */
213 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
214 rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL);
217 ERR_error_string(ERR_get_error(), ssl_errstring);
218 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
230 x509_store_dump_cert_s_names(X509_STORE * store)
232 STACK_OF(X509_OBJECT) * roots= store->objs;
234 static uschar name[256];
236 for(i= 0; i<sk_X509_OBJECT_num(roots); i++)
238 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
239 if(tmp_obj->type == X509_LU_X509)
241 X509 * current_cert= tmp_obj->data.x509;
242 X509_NAME_oneline(X509_get_subject_name(current_cert), CS name, sizeof(name));
243 debug_printf(" %s\n", name);
251 /*************************************************
252 * Callback for verification *
253 *************************************************/
255 /* The SSL library does certificate verification if set up to do so. This
256 callback has the current yes/no state is in "state". If verification succeeded,
257 we set up the tls_peerdn string. If verification failed, what happens depends
258 on whether the client is required to present a verifiable certificate or not.
260 If verification is optional, we change the state to yes, but still log the
261 verification error. For some reason (it really would help to have proper
262 documentation of OpenSSL), this callback function then gets called again, this
263 time with state = 1. In fact, that's useful, because we can set up the peerdn
264 value, but we must take care not to set the private verified flag on the second
267 Note: this function is not called if the client fails to present a certificate
268 when asked. We get here only if a certificate has been received. Handling of
269 optional verification for this case is done when requesting SSL to verify, by
270 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
272 May be called multiple times for different issues with a certificate, even
273 for a given "depth" in the certificate chain.
276 state current yes/no state as 1/0
277 x509ctx certificate information.
278 client TRUE for client startup, FALSE for server startup
280 Returns: 1 if verified, 0 if not
284 verify_callback(int state, X509_STORE_CTX *x509ctx,
285 tls_support *tlsp, BOOL *calledp, BOOL *optionalp)
287 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
288 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
289 static uschar txt[256];
291 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
295 log_write(0, LOG_MAIN, "SSL verify error: depth=%d error=%s cert=%s",
297 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)),
299 tlsp->certificate_verified = FALSE;
303 tlsp->peercert = X509_dup(cert);
304 return 0; /* reject */
306 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
307 "tls_try_verify_hosts)\n");
312 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, txt);
314 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
315 { /* client, wanting stapling */
316 /* Add the server cert's signing chain as the one
317 for the verification of the OCSP stapled information. */
319 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
324 #ifdef EXPERIMENTAL_TPDA
325 if (tlsp == &tls_out && client_static_cbinfo->event_action)
327 tlsp->peercert = X509_dup(cert);
328 if (tpda_raise_event(client_static_cbinfo->event_action,
329 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
331 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
332 "depth=%d cert=%s", depth, txt);
333 tlsp->certificate_verified = FALSE;
335 return 0; /* reject */
337 X509_free(tlsp->peercert);
338 tlsp->peercert = NULL;
344 #ifdef EXPERIMENTAL_CERTNAMES
345 uschar * verify_cert_hostnames;
349 tlsp->peercert = X509_dup(cert);
351 #ifdef EXPERIMENTAL_CERTNAMES
352 if ( tlsp == &tls_out
353 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
354 /* client, wanting hostname check */
356 # if OPENSSL_VERSION_NUMBER >= 0x010100000L || OPENSSL_VERSION_NUMBER >= 0x010002000L
357 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
358 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
362 uschar * list = verify_cert_hostnames;
365 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
366 if ((rc = X509_check_host(cert, name, 0,
367 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)))
371 log_write(0, LOG_MAIN, "SSL verify error: internal error\n");
378 log_write(0, LOG_MAIN,
379 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
380 return 0; /* reject */
384 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
386 log_write(0, LOG_MAIN,
387 "SSL verify error: certificate name mismatch: \"%s\"\n", txt);
388 return 0; /* reject */
391 #endif /*EXPERIMENTAL_CERTNAMES*/
393 #ifdef EXPERIMENTAL_TPDA
394 if (tlsp == &tls_out)
396 if (tpda_raise_event(client_static_cbinfo->event_action,
397 US"tls:cert", US"0") == DEFER)
399 log_write(0, LOG_MAIN, "SSL verify denied by event-action: "
400 "depth=0 cert=%s", txt);
401 tlsp->certificate_verified = FALSE;
403 return 0; /* reject */
408 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
409 *calledp ? "" : " authenticated", txt);
410 if (!*calledp) tlsp->certificate_verified = TRUE;
414 return 1; /* accept, at least for this level */
418 verify_callback_client(int state, X509_STORE_CTX *x509ctx)
420 return verify_callback(state, x509ctx, &tls_out, &client_verify_callback_called, &client_verify_optional);
424 verify_callback_server(int state, X509_STORE_CTX *x509ctx)
426 return verify_callback(state, x509ctx, &tls_in, &server_verify_callback_called, &server_verify_optional);
430 #ifdef EXPERIMENTAL_DANE
432 /* This gets called *by* the dane library verify callback, which interposes
436 verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
438 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
439 static uschar txt[256];
440 #ifdef EXPERIMENTAL_TPDA
441 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
444 X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
446 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
447 tls_out.peerdn = txt;
448 tls_out.peercert = X509_dup(cert);
450 #ifdef EXPERIMENTAL_TPDA
451 if (client_static_cbinfo->event_action)
453 if (tpda_raise_event(client_static_cbinfo->event_action,
454 US"tls:cert", string_sprintf("%d", depth)) == DEFER)
456 log_write(0, LOG_MAIN, "DANE verify denied by event-action: "
457 "depth=%d cert=%s", depth, txt);
458 tls_out.certificate_verified = FALSE;
459 return 0; /* reject */
463 X509_free(tls_out.peercert);
464 tls_out.peercert = NULL;
470 tls_out.dane_verified =
471 tls_out.certificate_verified = TRUE;
475 #endif /*EXPERIMENTAL_DANE*/
478 /*************************************************
479 * Information callback *
480 *************************************************/
482 /* The SSL library functions call this from time to time to indicate what they
483 are doing. We copy the string to the debugging output when TLS debugging has
495 info_callback(SSL *s, int where, int ret)
499 DEBUG(D_tls) debug_printf("SSL info: %s\n", SSL_state_string_long(s));
504 /*************************************************
505 * Initialize for DH *
506 *************************************************/
508 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
511 dhparam DH parameter file or fixed parameter identity string
512 host connected host, if client; NULL if server
514 Returns: TRUE if OK (nothing to set up, or setup worked)
518 init_dh(SSL_CTX *sctx, uschar *dhparam, host_item *host)
525 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded))
528 if (!dhexpanded || !*dhexpanded)
529 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
530 else if (dhexpanded[0] == '/')
532 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
534 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
535 host, US strerror(errno));
541 if (Ustrcmp(dhexpanded, "none") == 0)
543 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
547 if (!(pem = std_dh_prime_named(dhexpanded)))
549 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
550 host, US strerror(errno));
553 bio = BIO_new_mem_buf(CS pem, -1);
556 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
559 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
564 /* Even if it is larger, we silently return success rather than cause things
565 * to fail out, so that a too-large DH will not knock out all TLS; it's a
566 * debatable choice. */
567 if ((8*DH_size(dh)) > tls_dh_max_bits)
570 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d",
571 8*DH_size(dh), tls_dh_max_bits);
575 SSL_CTX_set_tmp_dh(sctx, dh);
577 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
578 dhexpanded ? dhexpanded : US"default", 8*DH_size(dh));
591 /*************************************************
592 * Load OCSP information into state *
593 *************************************************/
595 /* Called to load the server OCSP response from the given file into memory, once
596 caller has determined this is needed. Checks validity. Debugs a message
599 ASSUMES: single response, for single cert.
602 sctx the SSL_CTX* to update
603 cbinfo various parts of session state
604 expanded the filename putatively holding an OCSP response
609 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
613 OCSP_BASICRESP *basic_response;
614 OCSP_SINGLERESP *single_response;
615 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
617 unsigned long verify_flags;
618 int status, reason, i;
620 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
621 if (cbinfo->u_ocsp.server.response)
623 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
624 cbinfo->u_ocsp.server.response = NULL;
627 bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb");
630 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
631 cbinfo->u_ocsp.server.file_expanded);
635 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
639 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
643 status = OCSP_response_status(resp);
644 if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
646 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
647 OCSP_response_status_str(status), status);
651 basic_response = OCSP_response_get1_basic(resp);
655 debug_printf("OCSP response parse error: unable to extract basic response.\n");
659 store = SSL_CTX_get_cert_store(sctx);
660 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
662 /* May need to expose ability to adjust those flags?
663 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
664 OCSP_TRUSTOTHER OCSP_NOINTERN */
666 i = OCSP_basic_verify(basic_response, NULL, store, verify_flags);
670 ERR_error_string(ERR_get_error(), ssl_errstring);
671 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
676 /* Here's the simplifying assumption: there's only one response, for the
677 one certificate we use, and nothing for anything else in a chain. If this
678 proves false, we need to extract a cert id from our issued cert
679 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
680 right cert in the stack and then calls OCSP_single_get0_status()).
682 I'm hoping to avoid reworking a bunch more of how we handle state here. */
683 single_response = OCSP_resp_get0(basic_response, 0);
684 if (!single_response)
687 debug_printf("Unable to get first response from OCSP basic response.\n");
691 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
692 if (status != V_OCSP_CERTSTATUS_GOOD)
694 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
695 OCSP_cert_status_str(status), status,
696 OCSP_crl_reason_str(reason), reason);
700 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
702 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
707 cbinfo->u_ocsp.server.response = resp;
711 if (running_in_test_harness)
713 extern char ** environ;
715 for (p = USS environ; *p != NULL; p++)
716 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
718 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
719 goto supply_response;
724 #endif /*!DISABLE_OCSP*/
729 /*************************************************
730 * Expand key and cert file specs *
731 *************************************************/
733 /* Called once during tls_init and possibly again during TLS setup, for a
734 new context, if Server Name Indication was used and tls_sni was seen in
735 the certificate string.
738 sctx the SSL_CTX* to update
739 cbinfo various parts of session state
741 Returns: OK/DEFER/FAIL
745 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo)
749 if (cbinfo->certificate == NULL)
752 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
753 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
754 Ustrstr(cbinfo->certificate, US"tls_out_sni")
756 reexpand_tls_files_for_sni = TRUE;
758 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded))
761 if (expanded != NULL)
763 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", expanded);
764 if (!SSL_CTX_use_certificate_chain_file(sctx, CS expanded))
765 return tls_error(string_sprintf(
766 "SSL_CTX_use_certificate_chain_file file=%s", expanded),
770 if (cbinfo->privatekey != NULL &&
771 !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded))
774 /* If expansion was forced to fail, key_expanded will be NULL. If the result
775 of the expansion is an empty string, ignore it also, and assume the private
776 key is in the same file as the certificate. */
778 if (expanded != NULL && *expanded != 0)
780 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", expanded);
781 if (!SSL_CTX_use_PrivateKey_file(sctx, CS expanded, SSL_FILETYPE_PEM))
782 return tls_error(string_sprintf(
783 "SSL_CTX_use_PrivateKey_file file=%s", expanded), cbinfo->host, NULL);
787 if (cbinfo->is_server && cbinfo->u_ocsp.server.file != NULL)
789 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded))
792 if (expanded != NULL && *expanded != 0)
794 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
795 if (cbinfo->u_ocsp.server.file_expanded &&
796 (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
799 debug_printf("tls_ocsp_file value unchanged, using existing values.\n");
801 ocsp_load_response(sctx, cbinfo, expanded);
813 /*************************************************
814 * Callback to handle SNI *
815 *************************************************/
817 /* Called when acting as server during the TLS session setup if a Server Name
818 Indication extension was sent by the client.
820 API documentation is OpenSSL s_server.c implementation.
823 s SSL* of the current session
824 ad unknown (part of OpenSSL API) (unused)
825 arg Callback of "our" registered data
827 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
830 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
832 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
834 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
835 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
837 int old_pool = store_pool;
840 return SSL_TLSEXT_ERR_OK;
842 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
843 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
845 /* Make the extension value available for expansion */
846 store_pool = POOL_PERM;
847 tls_in.sni = string_copy(US servername);
848 store_pool = old_pool;
850 if (!reexpand_tls_files_for_sni)
851 return SSL_TLSEXT_ERR_OK;
853 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
854 not confident that memcpy wouldn't break some internal reference counting.
855 Especially since there's a references struct member, which would be off. */
857 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
859 ERR_error_string(ERR_get_error(), ssl_errstring);
860 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
861 return SSL_TLSEXT_ERR_NOACK;
864 /* Not sure how many of these are actually needed, since SSL object
865 already exists. Might even need this selfsame callback, for reneg? */
867 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
868 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
869 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
870 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
871 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
872 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
873 if (cbinfo->server_cipher_list)
874 SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list);
876 if (cbinfo->u_ocsp.server.file)
878 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
879 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
883 rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE, verify_callback_server);
884 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
886 /* do this after setup_certs, because this can require the certs for verifying
888 rc = tls_expand_session_files(server_sni, cbinfo);
889 if (rc != OK) return SSL_TLSEXT_ERR_NOACK;
891 if (!init_dh(server_sni, cbinfo->dhparam, NULL))
892 return SSL_TLSEXT_ERR_NOACK;
894 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
895 SSL_set_SSL_CTX(s, server_sni);
897 return SSL_TLSEXT_ERR_OK;
899 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
906 /*************************************************
907 * Callback to handle OCSP Stapling *
908 *************************************************/
910 /* Called when acting as server during the TLS session setup if the client
911 requests OCSP information with a Certificate Status Request.
913 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
919 tls_server_stapling_cb(SSL *s, void *arg)
921 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
922 uschar *response_der;
923 int response_der_len;
926 debug_printf("Received TLS status request (OCSP stapling); %s response.",
927 cbinfo->u_ocsp.server.response ? "have" : "lack");
929 tls_in.ocsp = OCSP_NOT_RESP;
930 if (!cbinfo->u_ocsp.server.response)
931 return SSL_TLSEXT_ERR_NOACK;
934 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
936 if (response_der_len <= 0)
937 return SSL_TLSEXT_ERR_NOACK;
939 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
940 tls_in.ocsp = OCSP_VFIED;
941 return SSL_TLSEXT_ERR_OK;
946 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
948 BIO_printf(bp, "\t%s: ", str);
949 ASN1_GENERALIZEDTIME_print(bp, time);
954 tls_client_stapling_cb(SSL *s, void *arg)
956 tls_ext_ctx_cb * cbinfo = arg;
957 const unsigned char * p;
963 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
964 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
967 /* Expect this when we requested ocsp but got none */
968 if ( cbinfo->u_ocsp.client.verify_required
969 && log_extra_selector & LX_tls_cipher)
970 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
972 DEBUG(D_tls) debug_printf(" null\n");
973 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
976 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
978 tls_out.ocsp = OCSP_FAILED;
979 if (log_extra_selector & LX_tls_cipher)
980 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
982 DEBUG(D_tls) debug_printf(" parse error\n");
986 if(!(bs = OCSP_response_get1_basic(rsp)))
988 tls_out.ocsp = OCSP_FAILED;
989 if (log_extra_selector & LX_tls_cipher)
990 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
992 DEBUG(D_tls) debug_printf(" error parsing response\n");
993 OCSP_RESPONSE_free(rsp);
997 /* We'd check the nonce here if we'd put one in the request. */
998 /* However that would defeat cacheability on the server so we don't. */
1000 /* This section of code reworked from OpenSSL apps source;
1001 The OpenSSL Project retains copyright:
1002 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1007 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1009 DEBUG(D_tls) bp = BIO_new_fp(stderr, BIO_NOCLOSE);
1011 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1013 /* Use the chain that verified the server cert to verify the stapled info */
1014 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1016 if ((i = OCSP_basic_verify(bs, NULL,
1017 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1019 tls_out.ocsp = OCSP_FAILED;
1020 if (log_extra_selector & LX_tls_cipher)
1021 log_write(0, LOG_MAIN, "Received TLS cert status response, itself unverifiable");
1022 BIO_printf(bp, "OCSP response verify failure\n");
1023 ERR_print_errors(bp);
1024 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1028 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1031 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1032 OCSP_SINGLERESP * single;
1034 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1036 tls_out.ocsp = OCSP_FAILED;
1037 log_write(0, LOG_MAIN, "OCSP stapling "
1038 "with multiple responses not handled");
1039 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1042 single = OCSP_resp_get0(bs, 0);
1043 status = OCSP_single_get0_status(single, &reason, &rev,
1044 &thisupd, &nextupd);
1047 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1048 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1049 if (!OCSP_check_validity(thisupd, nextupd,
1050 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1052 tls_out.ocsp = OCSP_FAILED;
1053 DEBUG(D_tls) ERR_print_errors(bp);
1054 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1055 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1059 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1060 OCSP_cert_status_str(status));
1063 case V_OCSP_CERTSTATUS_GOOD:
1064 tls_out.ocsp = OCSP_VFIED;
1067 case V_OCSP_CERTSTATUS_REVOKED:
1068 tls_out.ocsp = OCSP_FAILED;
1069 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1070 reason != -1 ? "; reason: " : "",
1071 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1072 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1073 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1076 tls_out.ocsp = OCSP_FAILED;
1077 log_write(0, LOG_MAIN,
1078 "Server certificate status unknown, in OCSP stapling");
1079 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1087 OCSP_RESPONSE_free(rsp);
1090 #endif /*!DISABLE_OCSP*/
1093 /*************************************************
1094 * Initialize for TLS *
1095 *************************************************/
1097 /* Called from both server and client code, to do preliminary initialization
1098 of the library. We allocate and return a context structure.
1101 ctxp returned SSL context
1102 host connected host, if client; NULL if server
1103 dhparam DH parameter file
1104 certificate certificate file
1105 privatekey private key
1106 ocsp_file file of stapling info (server); flag for require ocsp (client)
1107 addr address if client; NULL if server (for some randomness)
1108 cbp place to put allocated callback context
1110 Returns: OK/DEFER/FAIL
1114 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1116 #ifndef DISABLE_OCSP
1119 address_item *addr, tls_ext_ctx_cb ** cbp)
1124 tls_ext_ctx_cb * cbinfo;
1126 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1127 cbinfo->certificate = certificate;
1128 cbinfo->privatekey = privatekey;
1129 #ifndef DISABLE_OCSP
1130 if ((cbinfo->is_server = host==NULL))
1132 cbinfo->u_ocsp.server.file = ocsp_file;
1133 cbinfo->u_ocsp.server.file_expanded = NULL;
1134 cbinfo->u_ocsp.server.response = NULL;
1137 cbinfo->u_ocsp.client.verify_store = NULL;
1139 cbinfo->dhparam = dhparam;
1140 cbinfo->server_cipher_list = NULL;
1141 cbinfo->host = host;
1142 #ifdef EXPERIMENTAL_TPDA
1143 cbinfo->event_action = NULL;
1146 SSL_load_error_strings(); /* basic set up */
1147 OpenSSL_add_ssl_algorithms();
1149 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
1150 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1151 list of available digests. */
1152 EVP_add_digest(EVP_sha256());
1155 /* Create a context.
1156 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1157 negotiation in the different methods; as far as I can tell, the only
1158 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1159 when OpenSSL is built without SSLv2 support.
1160 By disabling with openssl_options, we can let admins re-enable with the
1163 *ctxp = SSL_CTX_new((host == NULL)?
1164 SSLv23_server_method() : SSLv23_client_method());
1166 if (*ctxp == NULL) return tls_error(US"SSL_CTX_new", host, NULL);
1168 /* It turns out that we need to seed the random number generator this early in
1169 order to get the full complement of ciphers to work. It took me roughly a day
1170 of work to discover this by experiment.
1172 On systems that have /dev/urandom, SSL may automatically seed itself from
1173 there. Otherwise, we have to make something up as best we can. Double check
1179 gettimeofday(&r.tv, NULL);
1182 RAND_seed((uschar *)(&r), sizeof(r));
1183 RAND_seed((uschar *)big_buffer, big_buffer_size);
1184 if (addr != NULL) RAND_seed((uschar *)addr, sizeof(addr));
1187 return tls_error(US"RAND_status", host,
1188 US"unable to seed random number generator");
1191 /* Set up the information callback, which outputs if debugging is at a suitable
1194 SSL_CTX_set_info_callback(*ctxp, (void (*)())info_callback);
1196 /* Automatically re-try reads/writes after renegotiation. */
1197 (void) SSL_CTX_set_mode(*ctxp, SSL_MODE_AUTO_RETRY);
1199 /* Apply administrator-supplied work-arounds.
1200 Historically we applied just one requested option,
1201 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1202 moved to an administrator-controlled list of options to specify and
1203 grandfathered in the first one as the default value for "openssl_options".
1205 No OpenSSL version number checks: the options we accept depend upon the
1206 availability of the option value macros from OpenSSL. */
1208 okay = tls_openssl_options_parse(openssl_options, &init_options);
1210 return tls_error(US"openssl_options parsing failed", host, NULL);
1214 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1215 if (!(SSL_CTX_set_options(*ctxp, init_options)))
1216 return tls_error(string_sprintf(
1217 "SSL_CTX_set_option(%#lx)", init_options), host, NULL);
1220 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
1222 /* Initialize with DH parameters if supplied */
1224 if (!init_dh(*ctxp, dhparam, host)) return DEFER;
1226 /* Set up certificate and key (and perhaps OCSP info) */
1228 rc = tls_expand_session_files(*ctxp, cbinfo);
1229 if (rc != OK) return rc;
1231 /* If we need to handle SNI, do so */
1232 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1233 if (host == NULL) /* server */
1235 # ifndef DISABLE_OCSP
1236 /* We check u_ocsp.server.file, not server.response, because we care about if
1237 the option exists, not what the current expansion might be, as SNI might
1238 change the certificate and OCSP file in use between now and the time the
1239 callback is invoked. */
1240 if (cbinfo->u_ocsp.server.file)
1242 SSL_CTX_set_tlsext_status_cb(server_ctx, tls_server_stapling_cb);
1243 SSL_CTX_set_tlsext_status_arg(server_ctx, cbinfo);
1246 /* We always do this, so that $tls_sni is available even if not used in
1248 SSL_CTX_set_tlsext_servername_callback(*ctxp, tls_servername_cb);
1249 SSL_CTX_set_tlsext_servername_arg(*ctxp, cbinfo);
1251 # ifndef DISABLE_OCSP
1253 if(ocsp_file) /* wanting stapling */
1255 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
1257 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
1260 SSL_CTX_set_tlsext_status_cb(*ctxp, tls_client_stapling_cb);
1261 SSL_CTX_set_tlsext_status_arg(*ctxp, cbinfo);
1266 #ifdef EXPERIMENTAL_CERTNAMES
1267 cbinfo->verify_cert_hostnames = NULL;
1270 /* Set up the RSA callback */
1272 SSL_CTX_set_tmp_rsa_callback(*ctxp, rsa_callback);
1274 /* Finally, set the timeout, and we are done */
1276 SSL_CTX_set_timeout(*ctxp, ssl_session_timeout);
1277 DEBUG(D_tls) debug_printf("Initialized TLS\n");
1287 /*************************************************
1288 * Get name of cipher in use *
1289 *************************************************/
1292 Argument: pointer to an SSL structure for the connection
1293 buffer to use for answer
1295 pointer to number of bits for cipher
1300 construct_cipher_name(SSL *ssl, uschar *cipherbuf, int bsize, int *bits)
1302 /* With OpenSSL 1.0.0a, this needs to be const but the documentation doesn't
1303 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
1304 the accessor functions use const in the prototype. */
1305 const SSL_CIPHER *c;
1308 ver = (const uschar *)SSL_get_version(ssl);
1310 c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
1311 SSL_CIPHER_get_bits(c, bits);
1313 string_format(cipherbuf, bsize, "%s:%s:%u", ver,
1314 SSL_CIPHER_get_name(c), *bits);
1316 DEBUG(D_tls) debug_printf("Cipher: %s\n", cipherbuf);
1323 /*************************************************
1324 * Set up for verifying certificates *
1325 *************************************************/
1327 /* Called by both client and server startup
1330 sctx SSL_CTX* to initialise
1331 certs certs file or NULL
1332 crl CRL file or NULL
1333 host NULL in a server; the remote host in a client
1334 optional TRUE if called from a server for a host in tls_try_verify_hosts;
1335 otherwise passed as FALSE
1336 cert_vfy_cb Callback function for certificate verification
1338 Returns: OK/DEFER/FAIL
1342 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
1343 int (*cert_vfy_cb)(int, X509_STORE_CTX *) )
1345 uschar *expcerts, *expcrl;
1347 if (!expand_check(certs, US"tls_verify_certificates", &expcerts))
1350 if (expcerts != NULL && *expcerts != '\0')
1352 struct stat statbuf;
1353 if (!SSL_CTX_set_default_verify_paths(sctx))
1354 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL);
1356 if (Ustat(expcerts, &statbuf) < 0)
1358 log_write(0, LOG_MAIN|LOG_PANIC,
1359 "failed to stat %s for certificates", expcerts);
1365 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
1366 { file = NULL; dir = expcerts; }
1368 { file = expcerts; dir = NULL; }
1370 /* If a certificate file is empty, the next function fails with an
1371 unhelpful error message. If we skip it, we get the correct behaviour (no
1372 certificates are recognized, but the error message is still misleading (it
1373 says no certificate was supplied.) But this is better. */
1375 if ((file == NULL || statbuf.st_size > 0) &&
1376 !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
1377 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL);
1381 SSL_CTX_set_client_CA_list(sctx, SSL_load_client_CA_file(CS file));
1385 /* Handle a certificate revocation list. */
1387 #if OPENSSL_VERSION_NUMBER > 0x00907000L
1389 /* This bit of code is now the version supplied by Lars Mainka. (I have
1390 * merely reformatted it into the Exim code style.)
1392 * "From here I changed the code to add support for multiple crl's
1393 * in pem format in one file or to support hashed directory entries in
1394 * pem format instead of a file. This method now uses the library function
1395 * X509_STORE_load_locations to add the CRL location to the SSL context.
1396 * OpenSSL will then handle the verify against CA certs and CRLs by
1397 * itself in the verify callback." */
1399 if (!expand_check(crl, US"tls_crl", &expcrl)) return DEFER;
1400 if (expcrl != NULL && *expcrl != 0)
1402 struct stat statbufcrl;
1403 if (Ustat(expcrl, &statbufcrl) < 0)
1405 log_write(0, LOG_MAIN|LOG_PANIC,
1406 "failed to stat %s for certificates revocation lists", expcrl);
1411 /* is it a file or directory? */
1413 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
1414 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
1418 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
1424 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
1426 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
1427 return tls_error(US"X509_STORE_load_locations", host, NULL);
1429 /* setting the flags to check against the complete crl chain */
1431 X509_STORE_set_flags(cvstore,
1432 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
1436 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
1438 /* If verification is optional, don't fail if no certificate */
1440 SSL_CTX_set_verify(sctx,
1441 SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
1450 /*************************************************
1451 * Start a TLS session in a server *
1452 *************************************************/
1454 /* This is called when Exim is running as a server, after having received
1455 the STARTTLS command. It must respond to that command, and then negotiate
1459 require_ciphers allowed ciphers
1461 Returns: OK on success
1462 DEFER for errors before the start of the negotiation
1463 FAIL for errors during the negotation; the server can't
1468 tls_server_start(const uschar *require_ciphers)
1472 tls_ext_ctx_cb *cbinfo;
1473 static uschar cipherbuf[256];
1475 /* Check for previous activation */
1477 if (tls_in.active >= 0)
1479 tls_error(US"STARTTLS received after TLS started", NULL, US"");
1480 smtp_printf("554 Already in TLS\r\n");
1484 /* Initialize the SSL library. If it fails, it will already have logged
1487 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
1488 #ifndef DISABLE_OCSP
1491 NULL, &server_static_cbinfo);
1492 if (rc != OK) return rc;
1493 cbinfo = server_static_cbinfo;
1495 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers))
1498 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1499 were historically separated by underscores. So that I can use either form in my
1500 tests, and also for general convenience, we turn underscores into hyphens here.
1503 if (expciphers != NULL)
1505 uschar *s = expciphers;
1506 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1507 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1508 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
1509 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL);
1510 cbinfo->server_cipher_list = expciphers;
1513 /* If this is a host for which certificate verification is mandatory or
1514 optional, set up appropriately. */
1516 tls_in.certificate_verified = FALSE;
1517 #ifdef EXPERIMENTAL_DANE
1518 tls_in.dane_verified = FALSE;
1520 server_verify_callback_called = FALSE;
1522 if (verify_check_host(&tls_verify_hosts) == OK)
1524 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1525 FALSE, verify_callback_server);
1526 if (rc != OK) return rc;
1527 server_verify_optional = FALSE;
1529 else if (verify_check_host(&tls_try_verify_hosts) == OK)
1531 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
1532 TRUE, verify_callback_server);
1533 if (rc != OK) return rc;
1534 server_verify_optional = TRUE;
1537 /* Prepare for new connection */
1539 if ((server_ssl = SSL_new(server_ctx)) == NULL) return tls_error(US"SSL_new", NULL, NULL);
1541 /* Warning: we used to SSL_clear(ssl) here, it was removed.
1543 * With the SSL_clear(), we get strange interoperability bugs with
1544 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
1545 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
1547 * The SSL_clear() call is to let an existing SSL* be reused, typically after
1548 * session shutdown. In this case, we have a brand new object and there's no
1549 * obvious reason to immediately clear it. I'm guessing that this was
1550 * originally added because of incomplete initialisation which the clear fixed,
1551 * in some historic release.
1554 /* Set context and tell client to go ahead, except in the case of TLS startup
1555 on connection, where outputting anything now upsets the clients and tends to
1556 make them disconnect. We need to have an explicit fflush() here, to force out
1557 the response. Other smtp_printf() calls do not need it, because in non-TLS
1558 mode, the fflush() happens when smtp_getc() is called. */
1560 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
1561 if (!tls_in.on_connect)
1563 smtp_printf("220 TLS go ahead\r\n");
1567 /* Now negotiate the TLS session. We put our own timer on it, since it seems
1568 that the OpenSSL library doesn't. */
1570 SSL_set_wfd(server_ssl, fileno(smtp_out));
1571 SSL_set_rfd(server_ssl, fileno(smtp_in));
1572 SSL_set_accept_state(server_ssl);
1574 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
1576 sigalrm_seen = FALSE;
1577 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
1578 rc = SSL_accept(server_ssl);
1583 tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL);
1584 if (ERR_get_error() == 0)
1585 log_write(0, LOG_MAIN,
1586 "TLS client disconnected cleanly (rejected our certificate?)");
1590 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
1592 /* TLS has been set up. Adjust the input functions to read via TLS,
1593 and initialize things. */
1595 construct_cipher_name(server_ssl, cipherbuf, sizeof(cipherbuf), &tls_in.bits);
1596 tls_in.cipher = cipherbuf;
1601 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)) != NULL)
1602 debug_printf("Shared ciphers: %s\n", buf);
1605 /* Record the certificate we presented */
1607 X509 * crt = SSL_get_certificate(server_ssl);
1608 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
1611 /* Only used by the server-side tls (tls_in), including tls_getc.
1612 Client-side (tls_out) reads (seem to?) go via
1613 smtp_read_response()/ip_recv().
1614 Hence no need to duplicate for _in and _out.
1616 ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
1617 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
1618 ssl_xfer_eof = ssl_xfer_error = 0;
1620 receive_getc = tls_getc;
1621 receive_ungetc = tls_ungetc;
1622 receive_feof = tls_feof;
1623 receive_ferror = tls_ferror;
1624 receive_smtp_buffered = tls_smtp_buffered;
1626 tls_in.active = fileno(smtp_out);
1634 tls_client_basic_ctx_init(SSL_CTX * ctx,
1635 host_item * host, smtp_transport_options_block * ob
1636 #ifdef EXPERIMENTAL_CERTNAMES
1637 , tls_ext_ctx_cb * cbinfo
1642 /* stick to the old behaviour for compatibility if tls_verify_certificates is
1643 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
1644 the specified host patterns if one of them is defined */
1646 if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
1647 (verify_check_host(&ob->tls_verify_hosts) == OK))
1649 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1650 ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
1652 client_verify_optional = FALSE;
1654 #ifdef EXPERIMENTAL_CERTNAMES
1655 if (ob->tls_verify_cert_hostnames)
1657 if (!expand_check(ob->tls_verify_cert_hostnames,
1658 US"tls_verify_cert_hostnames",
1659 &cbinfo->verify_cert_hostnames))
1661 if (cbinfo->verify_cert_hostnames)
1662 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
1663 cbinfo->verify_cert_hostnames);
1667 else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
1669 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
1670 ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
1672 client_verify_optional = TRUE;
1679 #ifdef EXPERIMENTAL_DANE
1681 tlsa_lookup(host_item * host, dns_answer * dnsa,
1682 BOOL dane_required, BOOL * dane)
1684 /* move this out to host.c given the similarity to dns_lookup() ? */
1686 uschar * fullname = buffer;
1688 /* TLSA lookup string */
1689 (void)sprintf(CS buffer, "_%d._tcp.%.256s", host->port, host->name);
1691 switch (dns_lookup(dnsa, buffer, T_TLSA, &fullname))
1694 return DEFER; /* just defer this TLS'd conn */
1700 log_write(0, LOG_MAIN, "DANE error: TLSA lookup failed");
1706 if (!dns_is_secure(dnsa))
1708 log_write(0, LOG_MAIN, "DANE error: TLSA lookup not DNSSEC");
1719 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
1723 const char * hostnames[2] = { CS host->name, NULL };
1726 if (DANESSL_init(ssl, NULL, hostnames) != 1)
1727 return tls_error(US"hostnames load", host, NULL);
1729 for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
1731 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
1732 ) if (rr->type == T_TLSA)
1734 uschar * p = rr->data;
1735 uint8_t usage, selector, mtype;
1736 const char * mdname;
1746 log_write(0, LOG_MAIN,
1747 "DANE error: TLSA record w/bad mtype 0x%x", mtype);
1749 case 0: mdname = NULL; break;
1750 case 1: mdname = "sha256"; break;
1751 case 2: mdname = "sha512"; break;
1754 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
1757 case 0: /* action not taken */
1758 return tls_error(US"tlsa load", host, NULL);
1762 tls_out.tlsa_usage |= 1<<usage;
1768 log_write(0, LOG_MAIN, "DANE error: No TLSA records");
1771 #endif /*EXPERIMENTAL_DANE*/
1775 /*************************************************
1776 * Start a TLS session in a client *
1777 *************************************************/
1779 /* Called from the smtp transport after STARTTLS has been accepted.
1782 fd the fd of the connection
1783 host connected host (for messages)
1784 addr the first address
1785 tb transport (always smtp)
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)
1796 smtp_transport_options_block * ob =
1797 (smtp_transport_options_block *)tb->options_block;
1798 static uschar txt[256];
1799 uschar * expciphers;
1802 static uschar cipherbuf[256];
1804 #ifndef DISABLE_OCSP
1805 BOOL request_ocsp = FALSE;
1806 BOOL require_ocsp = FALSE;
1808 #ifdef EXPERIMENTAL_DANE
1809 dns_answer tlsa_dnsa;
1814 #ifdef EXPERIMENTAL_DANE
1815 tls_out.dane_verified = FALSE;
1816 tls_out.tlsa_usage = 0;
1817 dane_required = verify_check_this_host(&ob->hosts_require_dane, NULL,
1818 host->name, host->address, NULL) == OK;
1820 if (host->dnssec == DS_YES)
1823 || verify_check_this_host(&ob->hosts_try_dane, NULL,
1824 host->name, host->address, NULL) == OK
1826 if ((rc = tlsa_lookup(host, &tlsa_dnsa, dane_required, &dane)) != OK)
1829 else if (dane_required)
1831 /*XXX a shame we only find this after making tcp & smtp connection */
1832 /* move the test earlier? */
1833 log_write(0, LOG_MAIN, "DANE error: previous lookup not DNSSEC");
1838 #ifndef DISABLE_OCSP
1840 if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1841 NULL, host->name, host->address, NULL) == OK))
1842 request_ocsp = TRUE;
1845 # ifdef EXPERIMENTAL_DANE
1847 && ob->hosts_request_ocsp[0] == '*'
1848 && ob->hosts_request_ocsp[1] == '\0'
1851 /* Unchanged from default. Use a safer one under DANE */
1852 request_ocsp = TRUE;
1853 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
1854 " {= {4}{$tls_out_tlsa_usage}} } "
1859 request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
1860 NULL, host->name, host->address, NULL) == OK;
1865 rc = tls_init(&client_ctx, host, NULL,
1866 ob->tls_certificate, ob->tls_privatekey,
1867 #ifndef DISABLE_OCSP
1868 (void *)(long)request_ocsp,
1870 addr, &client_static_cbinfo);
1871 if (rc != OK) return rc;
1873 tls_out.certificate_verified = FALSE;
1874 client_verify_callback_called = FALSE;
1876 if (!expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
1880 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
1881 are separated by underscores. So that I can use either form in my tests, and
1882 also for general convenience, we turn underscores into hyphens here. */
1884 if (expciphers != NULL)
1886 uschar *s = expciphers;
1887 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
1888 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
1889 if (!SSL_CTX_set_cipher_list(client_ctx, CS expciphers))
1890 return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
1893 #ifdef EXPERIMENTAL_DANE
1896 SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
1898 if (!DANESSL_library_init())
1899 return tls_error(US"library init", host, NULL);
1900 if (DANESSL_CTX_init(client_ctx) <= 0)
1901 return tls_error(US"context init", host, NULL);
1907 if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
1908 #ifdef EXPERIMENTAL_CERTNAMES
1909 , client_static_cbinfo
1914 if ((client_ssl = SSL_new(client_ctx)) == NULL)
1915 return tls_error(US"SSL_new", host, NULL);
1916 SSL_set_session_id_context(client_ssl, sid_ctx, Ustrlen(sid_ctx));
1917 SSL_set_fd(client_ssl, fd);
1918 SSL_set_connect_state(client_ssl);
1922 if (!expand_check(ob->tls_sni, US"tls_sni", &tls_out.sni))
1924 if (tls_out.sni == NULL)
1926 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
1928 else if (!Ustrlen(tls_out.sni))
1932 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1933 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tls_out.sni);
1934 SSL_set_tlsext_host_name(client_ssl, tls_out.sni);
1937 debug_printf("OpenSSL at build-time lacked SNI support, ignoring \"%s\"\n",
1943 #ifdef EXPERIMENTAL_DANE
1945 if ((rc = dane_tlsa_load(client_ssl, host, &tlsa_dnsa)) != OK)
1949 #ifndef DISABLE_OCSP
1950 /* Request certificate status at connection-time. If the server
1951 does OCSP stapling we will get the callback (set in tls_init()) */
1952 # ifdef EXPERIMENTAL_DANE
1956 if ( (s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")
1957 || (s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")
1959 { /* Re-eval now $tls_out_tlsa_usage is populated. If
1960 this means we avoid the OCSP request, we wasted the setup
1961 cost in tls_init(). */
1962 require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
1963 NULL, host->name, host->address, NULL) == OK;
1964 request_ocsp = require_ocsp ? TRUE
1965 : verify_check_this_host(&ob->hosts_request_ocsp,
1966 NULL, host->name, host->address, NULL) == OK;
1973 SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
1974 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
1975 tls_out.ocsp = OCSP_NOT_RESP;
1979 #ifdef EXPERIMENTAL_TPDA
1980 client_static_cbinfo->event_action = tb->tpda_event_action;
1983 #ifdef EXPERIMENTAL_TPDA
1984 client_static_cbinfo->event_action = tb->tpda_event_action;
1987 /* There doesn't seem to be a built-in timeout on connection. */
1989 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
1990 sigalrm_seen = FALSE;
1991 alarm(ob->command_timeout);
1992 rc = SSL_connect(client_ssl);
1995 #ifdef EXPERIMENTAL_DANE
1997 DANESSL_cleanup(client_ssl);
2001 return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
2003 DEBUG(D_tls) debug_printf("SSL_connect succeeded\n");
2005 /* Beware anonymous ciphers which lead to server_cert being NULL */
2006 /*XXX server_cert is never freed... use X509_free() */
2007 server_cert = SSL_get_peer_certificate (client_ssl);
2010 tls_out.peerdn = US X509_NAME_oneline(X509_get_subject_name(server_cert),
2011 CS txt, sizeof(txt));
2012 tls_out.peerdn = txt; /*XXX a static buffer... */
2015 tls_out.peerdn = NULL;
2017 construct_cipher_name(client_ssl, cipherbuf, sizeof(cipherbuf), &tls_out.bits);
2018 tls_out.cipher = cipherbuf;
2020 /* Record the certificate we presented */
2022 X509 * crt = SSL_get_certificate(client_ssl);
2023 tls_out.ourcert = crt ? X509_dup(crt) : NULL;
2026 tls_out.active = fd;
2034 /*************************************************
2035 * TLS version of getc *
2036 *************************************************/
2038 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
2039 it refills the buffer via the SSL reading function.
2042 Returns: the next character or EOF
2044 Only used by the server-side TLS.
2050 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
2055 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
2056 ssl_xfer_buffer, ssl_xfer_buffer_size);
2058 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
2059 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer, ssl_xfer_buffer_size);
2060 error = SSL_get_error(server_ssl, inbytes);
2063 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
2064 closed down, not that the socket itself has been closed down. Revert to
2065 non-SSL handling. */
2067 if (error == SSL_ERROR_ZERO_RETURN)
2069 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2071 receive_getc = smtp_getc;
2072 receive_ungetc = smtp_ungetc;
2073 receive_feof = smtp_feof;
2074 receive_ferror = smtp_ferror;
2075 receive_smtp_buffered = smtp_buffered;
2077 SSL_free(server_ssl);
2081 tls_in.cipher = NULL;
2082 tls_in.peerdn = NULL;
2088 /* Handle genuine errors */
2090 else if (error == SSL_ERROR_SSL)
2092 ERR_error_string(ERR_get_error(), ssl_errstring);
2093 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
2098 else if (error != SSL_ERROR_NONE)
2100 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2105 #ifndef DISABLE_DKIM
2106 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
2108 ssl_xfer_buffer_hwm = inbytes;
2109 ssl_xfer_buffer_lwm = 0;
2112 /* Something in the buffer; return next uschar */
2114 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
2119 /*************************************************
2120 * Read bytes from TLS channel *
2121 *************************************************/
2128 Returns: the number of bytes read
2129 -1 after a failed read
2131 Only used by the client-side TLS.
2135 tls_read(BOOL is_server, uschar *buff, size_t len)
2137 SSL *ssl = is_server ? server_ssl : client_ssl;
2141 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
2142 buff, (unsigned int)len);
2144 inbytes = SSL_read(ssl, CS buff, len);
2145 error = SSL_get_error(ssl, inbytes);
2147 if (error == SSL_ERROR_ZERO_RETURN)
2149 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2152 else if (error != SSL_ERROR_NONE)
2164 /*************************************************
2165 * Write bytes down TLS channel *
2166 *************************************************/
2170 is_server channel specifier
2174 Returns: the number of bytes after a successful write,
2175 -1 after a failed write
2177 Used by both server-side and client-side TLS.
2181 tls_write(BOOL is_server, const uschar *buff, size_t len)
2186 SSL *ssl = is_server ? server_ssl : client_ssl;
2188 DEBUG(D_tls) debug_printf("tls_do_write(%p, %d)\n", buff, left);
2191 DEBUG(D_tls) debug_printf("SSL_write(SSL, %p, %d)\n", buff, left);
2192 outbytes = SSL_write(ssl, CS buff, left);
2193 error = SSL_get_error(ssl, outbytes);
2194 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
2198 ERR_error_string(ERR_get_error(), ssl_errstring);
2199 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
2202 case SSL_ERROR_NONE:
2207 case SSL_ERROR_ZERO_RETURN:
2208 log_write(0, LOG_MAIN, "SSL channel closed on write");
2211 case SSL_ERROR_SYSCALL:
2212 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
2213 sender_fullhost ? sender_fullhost : US"<unknown>",
2217 log_write(0, LOG_MAIN, "SSL_write error %d", error);
2226 /*************************************************
2227 * Close down a TLS session *
2228 *************************************************/
2230 /* This is also called from within a delivery subprocess forked from the
2231 daemon, to shut down the TLS library, without actually doing a shutdown (which
2232 would tamper with the SSL session in the parent process).
2234 Arguments: TRUE if SSL_shutdown is to be called
2237 Used by both server-side and client-side TLS.
2241 tls_close(BOOL is_server, BOOL shutdown)
2243 SSL **sslp = is_server ? &server_ssl : &client_ssl;
2244 int *fdp = is_server ? &tls_in.active : &tls_out.active;
2246 if (*fdp < 0) return; /* TLS was not active */
2250 DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
2251 SSL_shutdown(*sslp);
2263 /*************************************************
2264 * Let tls_require_ciphers be checked at startup *
2265 *************************************************/
2267 /* The tls_require_ciphers option, if set, must be something which the
2270 Returns: NULL on success, or error message
2274 tls_validate_require_cipher(void)
2277 uschar *s, *expciphers, *err;
2279 /* this duplicates from tls_init(), we need a better "init just global
2280 state, for no specific purpose" singleton function of our own */
2282 SSL_load_error_strings();
2283 OpenSSL_add_ssl_algorithms();
2284 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
2285 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2286 list of available digests. */
2287 EVP_add_digest(EVP_sha256());
2290 if (!(tls_require_ciphers && *tls_require_ciphers))
2293 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers))
2294 return US"failed to expand tls_require_ciphers";
2296 if (!(expciphers && *expciphers))
2299 /* normalisation ripped from above */
2301 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
2305 ctx = SSL_CTX_new(SSLv23_server_method());
2308 ERR_error_string(ERR_get_error(), ssl_errstring);
2309 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
2313 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
2315 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
2317 ERR_error_string(ERR_get_error(), ssl_errstring);
2318 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed", expciphers);
2329 /*************************************************
2330 * Report the library versions. *
2331 *************************************************/
2333 /* There have historically been some issues with binary compatibility in
2334 OpenSSL libraries; if Exim (like many other applications) is built against
2335 one version of OpenSSL but the run-time linker picks up another version,
2336 it can result in serious failures, including crashing with a SIGSEGV. So
2337 report the version found by the compiler and the run-time version.
2339 Note: some OS vendors backport security fixes without changing the version
2340 number/string, and the version date remains unchanged. The _build_ date
2341 will change, so we can more usefully assist with version diagnosis by also
2342 reporting the build date.
2344 Arguments: a FILE* to print the results to
2349 tls_version_report(FILE *f)
2351 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
2354 OPENSSL_VERSION_TEXT,
2355 SSLeay_version(SSLEAY_VERSION),
2356 SSLeay_version(SSLEAY_BUILT_ON));
2357 /* third line is 38 characters for the %s and the line is 73 chars long;
2358 the OpenSSL output includes a "built on: " prefix already. */
2364 /*************************************************
2365 * Random number generation *
2366 *************************************************/
2368 /* Pseudo-random number generation. The result is not expected to be
2369 cryptographically strong but not so weak that someone will shoot themselves
2370 in the foot using it as a nonce in input in some email header scheme or
2371 whatever weirdness they'll twist this into. The result should handle fork()
2372 and avoid repeating sequences. OpenSSL handles that for us.
2376 Returns a random number in range [0, max-1]
2380 vaguely_random_number(int max)
2384 static pid_t pidlast = 0;
2387 uschar smallbuf[sizeof(r)];
2393 if (pidnow != pidlast)
2395 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
2396 is unique for each thread", this doesn't apparently apply across processes,
2397 so our own warning from vaguely_random_number_fallback() applies here too.
2398 Fix per PostgreSQL. */
2404 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
2408 gettimeofday(&r.tv, NULL);
2411 RAND_seed((uschar *)(&r), sizeof(r));
2413 /* We're after pseudo-random, not random; if we still don't have enough data
2414 in the internal PRNG then our options are limited. We could sleep and hope
2415 for entropy to come along (prayer technique) but if the system is so depleted
2416 in the first place then something is likely to just keep taking it. Instead,
2417 we'll just take whatever little bit of pseudo-random we can still manage to
2420 needed_len = sizeof(r);
2421 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
2422 asked for a number less than 10. */
2423 for (r = max, i = 0; r; ++i)
2429 /* We do not care if crypto-strong */
2430 i = RAND_pseudo_bytes(smallbuf, needed_len);
2434 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
2435 return vaguely_random_number_fallback(max);
2439 for (p = smallbuf; needed_len; --needed_len, ++p)
2445 /* We don't particularly care about weighted results; if someone wants
2446 smooth distribution and cares enough then they should submit a patch then. */
2453 /*************************************************
2454 * OpenSSL option parse *
2455 *************************************************/
2457 /* Parse one option for tls_openssl_options_parse below
2460 name one option name
2461 value place to store a value for it
2462 Returns success or failure in parsing
2465 struct exim_openssl_option {
2469 /* We could use a macro to expand, but we need the ifdef and not all the
2470 options document which version they were introduced in. Policylet: include
2471 all options unless explicitly for DTLS, let the administrator choose which
2474 This list is current as of:
2476 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
2478 static struct exim_openssl_option exim_openssl_options[] = {
2479 /* KEEP SORTED ALPHABETICALLY! */
2481 { US"all", SSL_OP_ALL },
2483 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
2484 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
2486 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
2487 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
2489 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
2490 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
2492 #ifdef SSL_OP_EPHEMERAL_RSA
2493 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
2495 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
2496 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
2498 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
2499 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
2501 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
2502 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
2504 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
2505 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
2507 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
2508 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
2510 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
2511 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
2513 #ifdef SSL_OP_NO_COMPRESSION
2514 { US"no_compression", SSL_OP_NO_COMPRESSION },
2516 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
2517 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
2519 #ifdef SSL_OP_NO_SSLv2
2520 { US"no_sslv2", SSL_OP_NO_SSLv2 },
2522 #ifdef SSL_OP_NO_SSLv3
2523 { US"no_sslv3", SSL_OP_NO_SSLv3 },
2525 #ifdef SSL_OP_NO_TICKET
2526 { US"no_ticket", SSL_OP_NO_TICKET },
2528 #ifdef SSL_OP_NO_TLSv1
2529 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
2531 #ifdef SSL_OP_NO_TLSv1_1
2532 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
2533 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
2534 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
2536 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
2539 #ifdef SSL_OP_NO_TLSv1_2
2540 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
2542 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
2543 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
2545 #ifdef SSL_OP_SINGLE_DH_USE
2546 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
2548 #ifdef SSL_OP_SINGLE_ECDH_USE
2549 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
2551 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
2552 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
2554 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
2555 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
2557 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
2558 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
2560 #ifdef SSL_OP_TLS_D5_BUG
2561 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
2563 #ifdef SSL_OP_TLS_ROLLBACK_BUG
2564 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
2567 static int exim_openssl_options_size =
2568 sizeof(exim_openssl_options)/sizeof(struct exim_openssl_option);
2572 tls_openssl_one_option_parse(uschar *name, long *value)
2575 int last = exim_openssl_options_size;
2576 while (last > first)
2578 int middle = (first + last)/2;
2579 int c = Ustrcmp(name, exim_openssl_options[middle].name);
2582 *value = exim_openssl_options[middle].value;
2596 /*************************************************
2597 * OpenSSL option parsing logic *
2598 *************************************************/
2600 /* OpenSSL has a number of compatibility options which an administrator might
2601 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
2602 we look like log_selector.
2605 option_spec the administrator-supplied string of options
2606 results ptr to long storage for the options bitmap
2607 Returns success or failure
2611 tls_openssl_options_parse(uschar *option_spec, long *results)
2616 BOOL adding, item_parsed;
2619 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
2620 * from default because it increases BEAST susceptibility. */
2621 #ifdef SSL_OP_NO_SSLv2
2622 result |= SSL_OP_NO_SSLv2;
2625 if (option_spec == NULL)
2631 for (s=option_spec; *s != '\0'; /**/)
2633 while (isspace(*s)) ++s;
2636 if (*s != '+' && *s != '-')
2638 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
2639 "+ or - expected but found \"%s\"\n", s);
2642 adding = *s++ == '+';
2643 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
2646 item_parsed = tls_openssl_one_option_parse(s, &item);
2649 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
2652 DEBUG(D_tls) debug_printf("openssl option, %s from %lx: %lx (%s)\n",
2653 adding ? "adding" : "removing", result, item, s);
2668 /* End of tls-openssl.c */