1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2019 */
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>
25 #ifndef OPENSSL_NO_ECDH
26 # include <openssl/ec.h>
29 # include <openssl/ocsp.h>
37 # define EXIM_OCSP_SKEW_SECONDS (300L)
38 # define EXIM_OCSP_MAX_AGE (-1L)
41 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
42 # define EXIM_HAVE_OPENSSL_TLSEXT
44 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
45 # define EXIM_HAVE_RSA_GENKEY_EX
47 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
48 # define EXIM_HAVE_OCSP_RESP_COUNT
50 # define EXIM_HAVE_EPHEM_RSA_KEX
51 # define EXIM_HAVE_RAND_PSEUDO
53 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
54 # define EXIM_HAVE_SHA256
57 /* X509_check_host provides sane certificate hostname checking, but was added
58 to OpenSSL late, after other projects forked off the code-base. So in
59 addition to guarding against the base version number, beware that LibreSSL
60 does not (at this time) support this function.
62 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
63 opt to disentangle and ask a LibreSSL user to provide glue for a third
64 crypto provider for libtls instead of continuing to tie the OpenSSL glue
65 into even twistier knots. If LibreSSL gains the same API, we can just
66 change this guard and punt the issue for a while longer. */
68 #ifndef LIBRESSL_VERSION_NUMBER
69 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
70 # define EXIM_HAVE_OPENSSL_CHECKHOST
71 # define EXIM_HAVE_OPENSSL_DH_BITS
72 # define EXIM_HAVE_OPENSSL_TLS_METHOD
73 # define EXIM_HAVE_OPENSSL_KEYLOG
74 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
75 # define EXIM_HAVE_SESSION_TICKET
76 # define EXIM_HAVE_OPESSL_TRACE
78 # define EXIM_NEED_OPENSSL_INIT
80 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
81 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
82 # define EXIM_HAVE_OPENSSL_CHECKHOST
86 #if !defined(LIBRESSL_VERSION_NUMBER) \
87 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
88 # if !defined(OPENSSL_NO_ECDH)
89 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
90 # define EXIM_HAVE_ECDH
92 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
93 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
98 #ifndef LIBRESSL_VERSION_NUMBER
99 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
100 # define OPENSSL_HAVE_KEYLOG_CB
101 # define OPENSSL_HAVE_NUM_TICKETS
102 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
106 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
107 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
108 # define DISABLE_OCSP
111 #ifdef EXPERIMENTAL_TLS_RESUME
112 # if OPENSSL_VERSION_NUMBER < 0x0101010L
113 # error OpenSSL version too old for session-resumption
117 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
118 # include <openssl/x509v3.h>
121 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
122 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
123 # define SSL_CIPHER_get_id(c) (c->id)
125 # ifndef MACRO_PREDEF
126 # include "tls-cipher-stdname.c"
130 /*************************************************
131 * OpenSSL option parse *
132 *************************************************/
134 typedef struct exim_openssl_option {
137 } exim_openssl_option;
138 /* We could use a macro to expand, but we need the ifdef and not all the
139 options document which version they were introduced in. Policylet: include
140 all options unless explicitly for DTLS, let the administrator choose which
143 This list is current as of:
145 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
146 Plus SSL_OP_NO_TLSv1_3 for 1.1.2-dev
148 static exim_openssl_option exim_openssl_options[] = {
149 /* KEEP SORTED ALPHABETICALLY! */
151 { US"all", SSL_OP_ALL },
153 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
154 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
156 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
157 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
159 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
160 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
162 #ifdef SSL_OP_EPHEMERAL_RSA
163 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
165 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
166 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
168 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
169 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
171 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
172 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
174 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
175 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
177 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
178 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
180 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
181 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
183 #ifdef SSL_OP_NO_COMPRESSION
184 { US"no_compression", SSL_OP_NO_COMPRESSION },
186 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
187 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
189 #ifdef SSL_OP_NO_SSLv2
190 { US"no_sslv2", SSL_OP_NO_SSLv2 },
192 #ifdef SSL_OP_NO_SSLv3
193 { US"no_sslv3", SSL_OP_NO_SSLv3 },
195 #ifdef SSL_OP_NO_TICKET
196 { US"no_ticket", SSL_OP_NO_TICKET },
198 #ifdef SSL_OP_NO_TLSv1
199 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
201 #ifdef SSL_OP_NO_TLSv1_1
202 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
203 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
204 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
206 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
209 #ifdef SSL_OP_NO_TLSv1_2
210 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
212 #ifdef SSL_OP_NO_TLSv1_3
213 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
215 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
216 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
218 #ifdef SSL_OP_SINGLE_DH_USE
219 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
221 #ifdef SSL_OP_SINGLE_ECDH_USE
222 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
224 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
225 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
227 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
228 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
230 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
231 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
233 #ifdef SSL_OP_TLS_D5_BUG
234 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
236 #ifdef SSL_OP_TLS_ROLLBACK_BUG
237 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
242 static int exim_openssl_options_size = nelem(exim_openssl_options);
251 for (struct exim_openssl_option * o = exim_openssl_options;
252 o < exim_openssl_options + nelem(exim_openssl_options); o++)
254 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
255 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
257 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
258 builtin_macro_create(buf);
261 # ifdef EXPERIMENTAL_TLS_RESUME
262 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
267 /******************************************************************************/
269 /* Structure for collecting random data for seeding. */
271 typedef struct randstuff {
276 /* Local static variables */
278 static BOOL client_verify_callback_called = FALSE;
279 static BOOL server_verify_callback_called = FALSE;
280 static const uschar *sid_ctx = US"exim";
282 /* We have three different contexts to care about.
284 Simple case: client, `client_ctx`
285 As a client, we can be doing a callout or cut-through delivery while receiving
286 a message. So we have a client context, which should have options initialised
287 from the SMTP Transport. We may also concurrently want to make TLS connections
288 to utility daemons, so client-contexts are allocated and passed around in call
289 args rather than using a gobal.
292 There are two cases: with and without ServerNameIndication from the client.
293 Given TLS SNI, we can be using different keys, certs and various other
294 configuration settings, because they're re-expanded with $tls_sni set. This
295 allows vhosting with TLS. This SNI is sent in the handshake.
296 A client might not send SNI, so we need a fallback, and an initial setup too.
297 So as a server, we start out using `server_ctx`.
298 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
299 `server_sni` from `server_ctx` and then initialise settings by re-expanding
307 } exim_openssl_client_tls_ctx;
309 static SSL_CTX *server_ctx = NULL;
310 static SSL *server_ssl = NULL;
312 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
313 static SSL_CTX *server_sni = NULL;
316 static char ssl_errstring[256];
318 static int ssl_session_timeout = 7200; /* Two hours */
319 static BOOL client_verify_optional = FALSE;
320 static BOOL server_verify_optional = FALSE;
322 static BOOL reexpand_tls_files_for_sni = FALSE;
325 typedef struct tls_ext_ctx_cb {
331 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
335 uschar *file_expanded;
336 OCSP_RESPONSE *response;
339 X509_STORE *verify_store; /* non-null if status requested */
340 BOOL verify_required;
345 /* these are cached from first expand */
346 uschar *server_cipher_list;
347 /* only passed down to tls_error: */
349 const uschar * verify_cert_hostnames;
350 #ifndef DISABLE_EVENT
351 uschar * event_action;
355 /* should figure out a cleanup of API to handle state preserved per
356 implementation, for various reasons, which can be void * in the APIs.
357 For now, we hack around it. */
358 tls_ext_ctx_cb *client_static_cbinfo = NULL; /*XXX should not use static; multiple concurrent clients! */
359 tls_ext_ctx_cb *server_static_cbinfo = NULL;
362 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
363 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
366 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
367 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
370 static int tls_server_stapling_cb(SSL *s, void *arg);
375 /* Daemon-called, before every connection, key create/rotate */
376 #ifdef EXPERIMENTAL_TLS_RESUME
377 static void tk_init(void);
378 static int tls_exdata_idx = -1;
382 tls_daemon_init(void)
384 #ifdef EXPERIMENTAL_TLS_RESUME
391 /*************************************************
393 *************************************************/
395 /* Called from lots of places when errors occur before actually starting to do
396 the TLS handshake, that is, while the session is still in clear. Always returns
397 DEFER for a server and FAIL for a client so that most calls can use "return
398 tls_error(...)" to do this processing and then give an appropriate return. A
399 single function is used for both server and client, because it is called from
400 some shared functions.
403 prefix text to include in the logged error
404 host NULL if setting up a server;
405 the connected host if setting up a client
406 msg error message or NULL if we should ask OpenSSL
407 errstr pointer to output error message
409 Returns: OK/DEFER/FAIL
413 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
417 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
418 msg = US ssl_errstring;
421 msg = string_sprintf("(%s): %s", prefix, msg);
422 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
423 if (errstr) *errstr = msg;
424 return host ? FAIL : DEFER;
429 /*************************************************
430 * Callback to generate RSA key *
431 *************************************************/
435 s SSL connection (not used)
439 Returns: pointer to generated key
443 rsa_callback(SSL *s, int export, int keylength)
446 #ifdef EXIM_HAVE_RSA_GENKEY_EX
447 BIGNUM *bn = BN_new();
450 export = export; /* Shut picky compilers up */
451 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
453 #ifdef EXIM_HAVE_RSA_GENKEY_EX
454 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
455 || !(rsa_key = RSA_new())
456 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
459 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
463 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
464 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
476 x509_store_dump_cert_s_names(X509_STORE * store)
478 STACK_OF(X509_OBJECT) * roots= store->objs;
479 static uschar name[256];
481 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
483 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
484 if(tmp_obj->type == X509_LU_X509)
486 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
487 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
489 name[sizeof(name)-1] = '\0';
490 debug_printf(" %s\n", name);
499 #ifndef DISABLE_EVENT
501 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
502 BOOL *calledp, const BOOL *optionalp, const uschar * what)
508 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
511 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
512 old_cert = tlsp->peercert;
513 tlsp->peercert = X509_dup(cert);
514 /* NB we do not bother setting peerdn */
515 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
517 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
518 "depth=%d cert=%s: %s",
519 tlsp == &tls_out ? deliver_host_address : sender_host_address,
520 what, depth, dn, yield);
524 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
525 return 1; /* reject (leaving peercert set) */
527 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
528 "(host in tls_try_verify_hosts)\n");
529 tlsp->verify_override = TRUE;
531 X509_free(tlsp->peercert);
532 tlsp->peercert = old_cert;
538 /*************************************************
539 * Callback for verification *
540 *************************************************/
542 /* The SSL library does certificate verification if set up to do so. This
543 callback has the current yes/no state is in "state". If verification succeeded,
544 we set the certificate-verified flag. If verification failed, what happens
545 depends on whether the client is required to present a verifiable certificate
548 If verification is optional, we change the state to yes, but still log the
549 verification error. For some reason (it really would help to have proper
550 documentation of OpenSSL), this callback function then gets called again, this
551 time with state = 1. We must take care not to set the private verified flag on
552 the second time through.
554 Note: this function is not called if the client fails to present a certificate
555 when asked. We get here only if a certificate has been received. Handling of
556 optional verification for this case is done when requesting SSL to verify, by
557 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
559 May be called multiple times for different issues with a certificate, even
560 for a given "depth" in the certificate chain.
563 preverify_ok current yes/no state as 1/0
564 x509ctx certificate information.
565 tlsp per-direction (client vs. server) support data
566 calledp has-been-called flag
567 optionalp verification-is-optional flag
569 Returns: 0 if verification should fail, otherwise 1
573 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
574 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
576 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
577 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
580 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
582 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
583 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
584 tlsp == &tls_out ? deliver_host_address : sender_host_address);
587 dn[sizeof(dn)-1] = '\0';
589 tlsp->verify_override = FALSE;
590 if (preverify_ok == 0)
592 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
593 *verify_mode, sender_host_address)
595 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
596 tlsp == &tls_out ? deliver_host_address : sender_host_address,
598 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
603 tlsp->peercert = X509_dup(cert); /* record failing cert */
604 return 0; /* reject */
606 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
607 "tls_try_verify_hosts)\n");
608 tlsp->verify_override = TRUE;
613 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
615 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
616 { /* client, wanting stapling */
617 /* Add the server cert's signing chain as the one
618 for the verification of the OCSP stapled information. */
620 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
623 sk_X509_push(client_static_cbinfo->verify_stack, cert);
626 #ifndef DISABLE_EVENT
627 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
628 return 0; /* reject, with peercert set */
633 const uschar * verify_cert_hostnames;
635 if ( tlsp == &tls_out
636 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
637 /* client, wanting hostname check */
640 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
641 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
642 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
644 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
645 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
648 const uschar * list = verify_cert_hostnames;
651 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
652 if ((rc = X509_check_host(cert, CCS name, 0,
653 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
654 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
659 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
660 tlsp == &tls_out ? deliver_host_address : sender_host_address);
667 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
670 uschar * extra = verify_mode
671 ? string_sprintf(" (during %c-verify for [%s])",
672 *verify_mode, sender_host_address)
674 log_write(0, LOG_MAIN,
675 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
676 tlsp == &tls_out ? deliver_host_address : sender_host_address,
677 extra, dn, verify_cert_hostnames);
682 tlsp->peercert = X509_dup(cert); /* record failing cert */
683 return 0; /* reject */
685 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
686 "tls_try_verify_hosts)\n");
687 tlsp->verify_override = TRUE;
691 #ifndef DISABLE_EVENT
692 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
693 return 0; /* reject, with peercert set */
696 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
697 *calledp ? "" : " authenticated", dn);
701 return 1; /* accept, at least for this level */
705 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
707 return verify_callback(preverify_ok, x509ctx, &tls_out,
708 &client_verify_callback_called, &client_verify_optional);
712 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
714 return verify_callback(preverify_ok, x509ctx, &tls_in,
715 &server_verify_callback_called, &server_verify_optional);
721 /* This gets called *by* the dane library verify callback, which interposes
725 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
727 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
729 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
730 #ifndef DISABLE_EVENT
731 BOOL dummy_called, optional = FALSE;
734 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
736 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
737 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
738 deliver_host_address);
741 dn[sizeof(dn)-1] = '\0';
743 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
744 preverify_ok ? "ok":"BAD", depth, dn);
746 #ifndef DISABLE_EVENT
747 if (verify_event(&tls_out, cert, depth, dn,
748 &dummy_called, &optional, US"DANE"))
749 return 0; /* reject, with peercert set */
752 if (preverify_ok == 1)
754 tls_out.dane_verified = TRUE;
756 if (client_static_cbinfo->u_ocsp.client.verify_store)
757 { /* client, wanting stapling */
758 /* Add the server cert's signing chain as the one
759 for the verification of the OCSP stapled information. */
761 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
764 sk_X509_push(client_static_cbinfo->verify_stack, cert);
770 int err = X509_STORE_CTX_get_error(x509ctx);
772 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
773 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
779 #endif /*SUPPORT_DANE*/
782 /*************************************************
783 * Information callback *
784 *************************************************/
786 /* The SSL library functions call this from time to time to indicate what they
787 are doing. We copy the string to the debugging output when TLS debugging has
799 info_callback(SSL *s, int where, int ret)
805 if (where & SSL_ST_CONNECT)
806 str = US"SSL_connect";
807 else if (where & SSL_ST_ACCEPT)
808 str = US"SSL_accept";
810 str = US"SSL info (undefined)";
812 if (where & SSL_CB_LOOP)
813 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
814 else if (where & SSL_CB_ALERT)
815 debug_printf("SSL3 alert %s:%s:%s\n",
816 str = where & SSL_CB_READ ? US"read" : US"write",
817 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
818 else if (where & SSL_CB_EXIT)
820 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
822 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
823 else if (where & SSL_CB_HANDSHAKE_START)
824 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
825 else if (where & SSL_CB_HANDSHAKE_DONE)
826 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
830 #ifdef OPENSSL_HAVE_KEYLOG_CB
832 keylog_callback(const SSL *ssl, const char *line)
834 DEBUG(D_tls) debug_printf("%.200s\n", line);
839 #ifdef EXPERIMENTAL_TLS_RESUME
840 /* Manage the keysets used for encrypting the session tickets, on the server. */
842 typedef struct { /* Session ticket encryption key */
845 const EVP_CIPHER * aes_cipher;
846 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
847 const EVP_MD * hmac_hash;
853 static exim_stek exim_tk; /* current key */
854 static exim_stek exim_tk_old; /* previous key */
859 time_t t = time(NULL);
863 if (exim_tk.renew >= t) return;
864 exim_tk_old = exim_tk;
867 if (f.running_in_test_harness) ssl_session_timeout = 6;
869 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
870 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
871 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
872 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
874 exim_tk.name[0] = 'E';
875 exim_tk.aes_cipher = EVP_aes_256_cbc();
876 exim_tk.hmac_hash = EVP_sha256();
877 exim_tk.expire = t + ssl_session_timeout;
878 exim_tk.renew = t + ssl_session_timeout/2;
884 if (!exim_tk.name[0]) return NULL;
889 tk_find(const uschar * name)
891 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
892 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
896 /* Callback for session tickets, on server */
898 ticket_key_callback(SSL * ssl, uschar key_name[16],
899 uschar * iv, EVP_CIPHER_CTX * ctx, HMAC_CTX * hctx, int enc)
901 tls_support * tlsp = server_static_cbinfo->tlsp;
906 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
907 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
909 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
910 return -1; /* insufficient random */
912 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
913 return 0; /* key couldn't be created */
914 memcpy(key_name, key->name, 16);
915 DEBUG(D_tls) debug_printf("STEK expire %ld\n", key->expire - time(NULL));
917 /*XXX will want these dependent on the ssl session strength */
918 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
919 key->hmac_hash, NULL);
920 EVP_EncryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
922 DEBUG(D_tls) debug_printf("ticket created\n");
927 time_t now = time(NULL);
929 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
930 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
932 if (!(key = tk_find(key_name)) || key->expire < now)
936 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
937 if (key) debug_printf("STEK expire %ld\n", key->expire - now);
942 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
943 key->hmac_hash, NULL);
944 EVP_DecryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
946 DEBUG(D_tls) debug_printf("ticket usable, STEK expire %ld\n", key->expire - now);
948 /* The ticket lifetime and renewal are the same as the STEK lifetime and
949 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
950 be better. To do that we'd have to encode ticket lifetime in the name as
951 we don't yet see the restored session. Could check posthandshake for TLS1.3
952 and trigger a new ticket then, but cannot do that for TLS1.2 */
953 return key->renew < now ? 2 : 1;
960 /*************************************************
961 * Initialize for DH *
962 *************************************************/
964 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
967 sctx The current SSL CTX (inbound or outbound)
968 dhparam DH parameter file or fixed parameter identity string
969 host connected host, if client; NULL if server
970 errstr error string pointer
972 Returns: TRUE if OK (nothing to set up, or setup worked)
976 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
984 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
987 if (!dhexpanded || !*dhexpanded)
988 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
989 else if (dhexpanded[0] == '/')
991 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
993 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
994 host, US strerror(errno), errstr);
1000 if (Ustrcmp(dhexpanded, "none") == 0)
1002 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
1006 if (!(pem = std_dh_prime_named(dhexpanded)))
1008 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
1009 host, US strerror(errno), errstr);
1012 bio = BIO_new_mem_buf(CS pem, -1);
1015 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
1018 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
1019 host, NULL, errstr);
1023 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
1024 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
1025 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
1026 * If someone wants to dance at the edge, then they can raise the limit or use
1027 * current libraries. */
1028 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
1029 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
1030 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
1031 dh_bitsize = DH_bits(dh);
1033 dh_bitsize = 8 * DH_size(dh);
1036 /* Even if it is larger, we silently return success rather than cause things
1037 * to fail out, so that a too-large DH will not knock out all TLS; it's a
1038 * debatable choice. */
1039 if (dh_bitsize > tls_dh_max_bits)
1042 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
1043 dh_bitsize, tls_dh_max_bits);
1047 SSL_CTX_set_tmp_dh(sctx, dh);
1049 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
1050 dhexpanded ? dhexpanded : US"default", dh_bitsize);
1062 /*************************************************
1063 * Initialize for ECDH *
1064 *************************************************/
1066 /* Load parameters for ECDH encryption.
1068 For now, we stick to NIST P-256 because: it's simple and easy to configure;
1069 it avoids any patent issues that might bite redistributors; despite events in
1070 the news and concerns over curve choices, we're not cryptographers, we're not
1071 pretending to be, and this is "good enough" to be better than no support,
1072 protecting against most adversaries. Given another year or two, there might
1073 be sufficient clarity about a "right" way forward to let us make an informed
1074 decision, instead of a knee-jerk reaction.
1076 Longer-term, we should look at supporting both various named curves and
1077 external files generated with "openssl ecparam", much as we do for init_dh().
1078 We should also support "none" as a value, to explicitly avoid initialisation.
1083 sctx The current SSL CTX (inbound or outbound)
1084 host connected host, if client; NULL if server
1085 errstr error string pointer
1087 Returns: TRUE if OK (nothing to set up, or setup worked)
1091 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
1093 #ifdef OPENSSL_NO_ECDH
1102 if (host) /* No ECDH setup for clients, only for servers */
1105 # ifndef EXIM_HAVE_ECDH
1107 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
1111 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
1113 if (!exp_curve || !*exp_curve)
1116 /* "auto" needs to be handled carefully.
1117 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
1118 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
1119 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
1120 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
1121 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
1123 if (Ustrcmp(exp_curve, "auto") == 0)
1125 #if OPENSSL_VERSION_NUMBER < 0x10002000L
1126 DEBUG(D_tls) debug_printf(
1127 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
1128 exp_curve = US"prime256v1";
1130 # if defined SSL_CTRL_SET_ECDH_AUTO
1131 DEBUG(D_tls) debug_printf(
1132 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
1133 SSL_CTX_set_ecdh_auto(sctx, 1);
1136 DEBUG(D_tls) debug_printf(
1137 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
1143 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
1144 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
1145 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
1146 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
1150 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
1151 host, NULL, errstr);
1155 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
1157 tls_error(US"Unable to create ec curve", host, NULL, errstr);
1161 /* The "tmp" in the name here refers to setting a temporary key
1162 not to the stability of the interface. */
1164 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
1165 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
1167 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
1172 # endif /*EXIM_HAVE_ECDH*/
1173 #endif /*OPENSSL_NO_ECDH*/
1179 #ifndef DISABLE_OCSP
1180 /*************************************************
1181 * Load OCSP information into state *
1182 *************************************************/
1183 /* Called to load the server OCSP response from the given file into memory, once
1184 caller has determined this is needed. Checks validity. Debugs a message
1187 ASSUMES: single response, for single cert.
1190 sctx the SSL_CTX* to update
1191 cbinfo various parts of session state
1192 expanded the filename putatively holding an OCSP response
1197 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
1200 OCSP_RESPONSE * resp;
1201 OCSP_BASICRESP * basic_response;
1202 OCSP_SINGLERESP * single_response;
1203 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1204 STACK_OF(X509) * sk;
1205 unsigned long verify_flags;
1206 int status, reason, i;
1208 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
1209 if (cbinfo->u_ocsp.server.response)
1211 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
1212 cbinfo->u_ocsp.server.response = NULL;
1215 if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb")))
1217 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
1218 cbinfo->u_ocsp.server.file_expanded);
1222 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1226 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
1230 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1232 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1233 OCSP_response_status_str(status), status);
1237 if (!(basic_response = OCSP_response_get1_basic(resp)))
1240 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1244 sk = cbinfo->verify_stack;
1245 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1247 /* May need to expose ability to adjust those flags?
1248 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1249 OCSP_TRUSTOTHER OCSP_NOINTERN */
1251 /* This does a full verify on the OCSP proof before we load it for serving
1252 up; possibly overkill - just date-checks might be nice enough.
1254 OCSP_basic_verify takes a "store" arg, but does not
1255 use it for the chain verification, which is all we do
1256 when OCSP_NOVERIFY is set. The content from the wire
1257 "basic_response" and a cert-stack "sk" are all that is used.
1259 We have a stack, loaded in setup_certs() if tls_verify_certificates
1260 was a file (not a directory, or "system"). It is unfortunate we
1261 cannot used the connection context store, as that would neatly
1262 handle the "system" case too, but there seems to be no library
1263 function for getting a stack from a store.
1264 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1265 We do not free the stack since it could be needed a second time for
1268 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1269 be a public interface into the OpenSSL library (there's no manual entry) -
1270 But what with? We also use OCSP_basic_verify in the client stapling callback.
1271 And there we NEED it; we must verify that status... unless the
1272 library does it for us anyway? */
1274 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1278 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1279 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1284 /* Here's the simplifying assumption: there's only one response, for the
1285 one certificate we use, and nothing for anything else in a chain. If this
1286 proves false, we need to extract a cert id from our issued cert
1287 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1288 right cert in the stack and then calls OCSP_single_get0_status()).
1290 I'm hoping to avoid reworking a bunch more of how we handle state here. */
1292 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1295 debug_printf("Unable to get first response from OCSP basic response.\n");
1299 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1300 if (status != V_OCSP_CERTSTATUS_GOOD)
1302 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1303 OCSP_cert_status_str(status), status,
1304 OCSP_crl_reason_str(reason), reason);
1308 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1310 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1315 cbinfo->u_ocsp.server.response = resp; /*XXX stack?*/
1319 if (f.running_in_test_harness)
1321 extern char ** environ;
1322 if (environ) for (uschar ** p = USS environ; *p; p++)
1323 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1325 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1326 goto supply_response;
1331 #endif /*!DISABLE_OCSP*/
1336 /* Create and install a selfsigned certificate, for use in server mode */
1339 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
1347 where = US"allocating pkey";
1348 if (!(pkey = EVP_PKEY_new()))
1351 where = US"allocating cert";
1352 if (!(x509 = X509_new()))
1355 where = US"generating pkey";
1356 if (!(rsa = rsa_callback(NULL, 0, 2048)))
1359 where = US"assigning pkey";
1360 if (!EVP_PKEY_assign_RSA(pkey, rsa))
1363 X509_set_version(x509, 2); /* N+1 - version 3 */
1364 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
1365 X509_gmtime_adj(X509_get_notBefore(x509), 0);
1366 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1367 X509_set_pubkey(x509, pkey);
1369 name = X509_get_subject_name(x509);
1370 X509_NAME_add_entry_by_txt(name, "C",
1371 MBSTRING_ASC, CUS "UK", -1, -1, 0);
1372 X509_NAME_add_entry_by_txt(name, "O",
1373 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
1374 X509_NAME_add_entry_by_txt(name, "CN",
1375 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
1376 X509_set_issuer_name(x509, name);
1378 where = US"signing cert";
1379 if (!X509_sign(x509, pkey, EVP_md5()))
1382 where = US"installing selfsign cert";
1383 if (!SSL_CTX_use_certificate(sctx, x509))
1386 where = US"installing selfsign key";
1387 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1393 (void) tls_error(where, NULL, NULL, errstr);
1394 if (x509) X509_free(x509);
1395 if (pkey) EVP_PKEY_free(pkey);
1403 tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1406 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file);
1407 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1408 return tls_error(string_sprintf(
1409 "SSL_CTX_use_certificate_chain_file file=%s", file),
1410 cbinfo->host, NULL, errstr);
1415 tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1418 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file);
1419 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1420 return tls_error(string_sprintf(
1421 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1426 /*************************************************
1427 * Expand key and cert file specs *
1428 *************************************************/
1430 /* Called once during tls_init and possibly again during TLS setup, for a
1431 new context, if Server Name Indication was used and tls_sni was seen in
1432 the certificate string.
1435 sctx the SSL_CTX* to update
1436 cbinfo various parts of session state
1437 errstr error string pointer
1439 Returns: OK/DEFER/FAIL
1443 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo,
1448 if (!cbinfo->certificate)
1450 if (!cbinfo->is_server) /* client */
1453 if (tls_install_selfsign(sctx, errstr) != OK)
1460 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
1461 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
1462 Ustrstr(cbinfo->certificate, US"tls_out_sni")
1464 reexpand_tls_files_for_sni = TRUE;
1466 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
1470 if (cbinfo->is_server)
1472 const uschar * file_list = expanded;
1476 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1477 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1480 else /* would there ever be a need for multiple client certs? */
1481 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1484 if ( cbinfo->privatekey
1485 && !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
1488 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1489 of the expansion is an empty string, ignore it also, and assume the private
1490 key is in the same file as the certificate. */
1492 if (expanded && *expanded)
1493 if (cbinfo->is_server)
1495 const uschar * file_list = expanded;
1499 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1500 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1503 else /* would there ever be a need for multiple client certs? */
1504 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1508 #ifndef DISABLE_OCSP
1509 if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
1512 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr))
1515 if (expanded && *expanded)
1517 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
1518 if ( cbinfo->u_ocsp.server.file_expanded
1519 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
1521 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1524 ocsp_load_response(sctx, cbinfo, expanded);
1535 /*************************************************
1536 * Callback to handle SNI *
1537 *************************************************/
1539 /* Called when acting as server during the TLS session setup if a Server Name
1540 Indication extension was sent by the client.
1542 API documentation is OpenSSL s_server.c implementation.
1545 s SSL* of the current session
1546 ad unknown (part of OpenSSL API) (unused)
1547 arg Callback of "our" registered data
1549 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1551 XXX might need to change to using ClientHello callback,
1552 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
1555 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1557 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1559 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
1560 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1562 int old_pool = store_pool;
1563 uschar * dummy_errstr;
1566 return SSL_TLSEXT_ERR_OK;
1568 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1569 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1571 /* Make the extension value available for expansion */
1572 store_pool = POOL_PERM;
1573 tls_in.sni = string_copy(US servername);
1574 store_pool = old_pool;
1576 if (!reexpand_tls_files_for_sni)
1577 return SSL_TLSEXT_ERR_OK;
1579 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1580 not confident that memcpy wouldn't break some internal reference counting.
1581 Especially since there's a references struct member, which would be off. */
1583 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1584 if (!(server_sni = SSL_CTX_new(TLS_server_method())))
1586 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1589 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1590 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1594 /* Not sure how many of these are actually needed, since SSL object
1595 already exists. Might even need this selfsame callback, for reneg? */
1597 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1598 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1599 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1600 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1601 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1602 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1604 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1605 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1609 if ( cbinfo->server_cipher_list
1610 && !SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list))
1613 #ifndef DISABLE_OCSP
1614 if (cbinfo->u_ocsp.server.file)
1616 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1617 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1621 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1622 verify_callback_server, &dummy_errstr)) != OK)
1625 /* do this after setup_certs, because this can require the certs for verifying
1626 OCSP information. */
1627 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1630 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1631 SSL_set_SSL_CTX(s, server_sni);
1632 return SSL_TLSEXT_ERR_OK;
1634 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
1636 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1641 #ifndef DISABLE_OCSP
1643 /*************************************************
1644 * Callback to handle OCSP Stapling *
1645 *************************************************/
1647 /* Called when acting as server during the TLS session setup if the client
1648 requests OCSP information with a Certificate Status Request.
1650 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1656 tls_server_stapling_cb(SSL *s, void *arg)
1658 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1659 uschar *response_der; /*XXX blob */
1660 int response_der_len;
1662 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1663 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1664 buggy in current OpenSSL; it returns the last cert loaded always rather than
1665 the one actually presented. So we can't support a stack of OCSP proofs at
1669 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1670 cbinfo->u_ocsp.server.response ? "have" : "lack");
1672 tls_in.ocsp = OCSP_NOT_RESP;
1673 if (!cbinfo->u_ocsp.server.response)
1674 return SSL_TLSEXT_ERR_NOACK;
1676 response_der = NULL;
1677 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
1679 if (response_der_len <= 0)
1680 return SSL_TLSEXT_ERR_NOACK;
1682 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1683 tls_in.ocsp = OCSP_VFIED;
1684 return SSL_TLSEXT_ERR_OK;
1689 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1691 BIO_printf(bp, "\t%s: ", str);
1692 ASN1_GENERALIZEDTIME_print(bp, time);
1697 tls_client_stapling_cb(SSL *s, void *arg)
1699 tls_ext_ctx_cb * cbinfo = arg;
1700 const unsigned char * p;
1702 OCSP_RESPONSE * rsp;
1703 OCSP_BASICRESP * bs;
1706 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1707 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1710 /* Expect this when we requested ocsp but got none */
1711 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1712 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1714 DEBUG(D_tls) debug_printf(" null\n");
1715 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1718 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1720 tls_out.ocsp = OCSP_FAILED;
1721 if (LOGGING(tls_cipher))
1722 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1724 DEBUG(D_tls) debug_printf(" parse error\n");
1728 if(!(bs = OCSP_response_get1_basic(rsp)))
1730 tls_out.ocsp = OCSP_FAILED;
1731 if (LOGGING(tls_cipher))
1732 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1734 DEBUG(D_tls) debug_printf(" error parsing response\n");
1735 OCSP_RESPONSE_free(rsp);
1739 /* We'd check the nonce here if we'd put one in the request. */
1740 /* However that would defeat cacheability on the server so we don't. */
1742 /* This section of code reworked from OpenSSL apps source;
1743 The OpenSSL Project retains copyright:
1744 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1749 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1751 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1753 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1755 /* Use the chain that verified the server cert to verify the stapled info */
1756 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1758 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1759 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1761 tls_out.ocsp = OCSP_FAILED;
1762 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1763 "Received TLS cert status response, itself unverifiable: %s",
1764 ERR_reason_error_string(ERR_peek_error()));
1765 BIO_printf(bp, "OCSP response verify failure\n");
1766 ERR_print_errors(bp);
1767 OCSP_RESPONSE_print(bp, rsp, 0);
1771 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1773 /*XXX So we have a good stapled OCSP status. How do we know
1774 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1775 OCSP_resp_find_status() which matches on a cert id, which presumably
1776 we should use. Making an id needs OCSP_cert_id_new(), which takes
1777 issuerName, issuerKey, serialNumber. Are they all in the cert?
1779 For now, carry on blindly accepting the resp. */
1782 OCSP_SINGLERESP * single;
1784 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1785 if (OCSP_resp_count(bs) != 1)
1787 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1788 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1791 tls_out.ocsp = OCSP_FAILED;
1792 log_write(0, LOG_MAIN, "OCSP stapling "
1793 "with multiple responses not handled");
1796 single = OCSP_resp_get0(bs, 0);
1797 status = OCSP_single_get0_status(single, &reason, &rev,
1798 &thisupd, &nextupd);
1801 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1802 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1803 if (!OCSP_check_validity(thisupd, nextupd,
1804 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1806 tls_out.ocsp = OCSP_FAILED;
1807 DEBUG(D_tls) ERR_print_errors(bp);
1808 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1812 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1813 OCSP_cert_status_str(status));
1816 case V_OCSP_CERTSTATUS_GOOD:
1817 tls_out.ocsp = OCSP_VFIED;
1820 case V_OCSP_CERTSTATUS_REVOKED:
1821 tls_out.ocsp = OCSP_FAILED;
1822 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1823 reason != -1 ? "; reason: " : "",
1824 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1825 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1828 tls_out.ocsp = OCSP_FAILED;
1829 log_write(0, LOG_MAIN,
1830 "Server certificate status unknown, in OCSP stapling");
1835 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1840 OCSP_RESPONSE_free(rsp);
1843 #endif /*!DISABLE_OCSP*/
1846 /*************************************************
1847 * Initialize for TLS *
1848 *************************************************/
1850 /* Called from both server and client code, to do preliminary initialization
1851 of the library. We allocate and return a context structure.
1854 ctxp returned SSL context
1855 host connected host, if client; NULL if server
1856 dhparam DH parameter file
1857 certificate certificate file
1858 privatekey private key
1859 ocsp_file file of stapling info (server); flag for require ocsp (client)
1860 addr address if client; NULL if server (for some randomness)
1861 cbp place to put allocated callback context
1862 errstr error string pointer
1864 Returns: OK/DEFER/FAIL
1868 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1870 #ifndef DISABLE_OCSP
1871 uschar *ocsp_file, /*XXX stack, in server*/
1873 address_item *addr, tls_ext_ctx_cb ** cbp,
1880 tls_ext_ctx_cb * cbinfo;
1882 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1883 cbinfo->tlsp = tlsp;
1884 cbinfo->certificate = certificate;
1885 cbinfo->privatekey = privatekey;
1886 cbinfo->is_server = host==NULL;
1887 #ifndef DISABLE_OCSP
1888 cbinfo->verify_stack = NULL;
1891 cbinfo->u_ocsp.server.file = ocsp_file;
1892 cbinfo->u_ocsp.server.file_expanded = NULL;
1893 cbinfo->u_ocsp.server.response = NULL;
1896 cbinfo->u_ocsp.client.verify_store = NULL;
1898 cbinfo->dhparam = dhparam;
1899 cbinfo->server_cipher_list = NULL;
1900 cbinfo->host = host;
1901 #ifndef DISABLE_EVENT
1902 cbinfo->event_action = NULL;
1905 #ifdef EXIM_NEED_OPENSSL_INIT
1906 SSL_load_error_strings(); /* basic set up */
1907 OpenSSL_add_ssl_algorithms();
1910 #ifdef EXIM_HAVE_SHA256
1911 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1912 list of available digests. */
1913 EVP_add_digest(EVP_sha256());
1916 /* Create a context.
1917 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1918 negotiation in the different methods; as far as I can tell, the only
1919 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1920 when OpenSSL is built without SSLv2 support.
1921 By disabling with openssl_options, we can let admins re-enable with the
1924 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1925 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1927 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1929 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1931 /* It turns out that we need to seed the random number generator this early in
1932 order to get the full complement of ciphers to work. It took me roughly a day
1933 of work to discover this by experiment.
1935 On systems that have /dev/urandom, SSL may automatically seed itself from
1936 there. Otherwise, we have to make something up as best we can. Double check
1942 gettimeofday(&r.tv, NULL);
1945 RAND_seed(US (&r), sizeof(r));
1946 RAND_seed(US big_buffer, big_buffer_size);
1947 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
1950 return tls_error(US"RAND_status", host,
1951 US"unable to seed random number generator", errstr);
1954 /* Set up the information callback, which outputs if debugging is at a suitable
1959 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1960 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1961 /* this needs a debug build of OpenSSL */
1962 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1964 #ifdef OPENSSL_HAVE_KEYLOG_CB
1965 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1969 /* Automatically re-try reads/writes after renegotiation. */
1970 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1972 /* Apply administrator-supplied work-arounds.
1973 Historically we applied just one requested option,
1974 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1975 moved to an administrator-controlled list of options to specify and
1976 grandfathered in the first one as the default value for "openssl_options".
1978 No OpenSSL version number checks: the options we accept depend upon the
1979 availability of the option value macros from OpenSSL. */
1981 if (!tls_openssl_options_parse(openssl_options, &init_options))
1982 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
1984 #ifdef EXPERIMENTAL_TLS_RESUME
1985 tlsp->resumption = RESUME_SUPPORTED;
1989 #ifdef EXPERIMENTAL_TLS_RESUME
1990 /* Should the server offer session resumption? */
1991 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
1993 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
1994 init_options &= ~SSL_OP_NO_TICKET;
1995 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
1996 tlsp->host_resumable = TRUE;
2000 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2001 if (!(SSL_CTX_set_options(ctx, init_options)))
2002 return tls_error(string_sprintf(
2003 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2006 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2008 /* We'd like to disable session cache unconditionally, but foolish Outlook
2009 Express clients then give up the first TLS connection and make a second one
2010 (which works). Only when there is an IMAP service on the same machine.
2011 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2012 now, until we work out a decent way of presenting control to the config. It
2013 will never be used because we use a new context every time. */
2015 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2018 /* Initialize with DH parameters if supplied */
2019 /* Initialize ECDH temp key parameter selection */
2021 if ( !init_dh(ctx, dhparam, host, errstr)
2022 || !init_ecdh(ctx, host, errstr)
2026 /* Set up certificate and key (and perhaps OCSP info) */
2028 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
2031 /* If we need to handle SNI or OCSP, do so */
2033 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2034 # ifndef DISABLE_OCSP
2035 if (!(cbinfo->verify_stack = sk_X509_new_null()))
2037 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2042 if (!host) /* server */
2044 # ifndef DISABLE_OCSP
2045 /* We check u_ocsp.server.file, not server.response, because we care about if
2046 the option exists, not what the current expansion might be, as SNI might
2047 change the certificate and OCSP file in use between now and the time the
2048 callback is invoked. */
2049 if (cbinfo->u_ocsp.server.file)
2051 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2052 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2055 /* We always do this, so that $tls_sni is available even if not used in
2057 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2058 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
2060 # ifndef DISABLE_OCSP
2062 if(ocsp_file) /* wanting stapling */
2064 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
2066 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2069 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2070 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2075 cbinfo->verify_cert_hostnames = NULL;
2077 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2078 /* Set up the RSA callback */
2079 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2082 /* Finally, set the session cache timeout, and we are done.
2083 The period appears to be also used for (server-generated) session tickets */
2085 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2086 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2097 /*************************************************
2098 * Get name of cipher in use *
2099 *************************************************/
2102 Argument: pointer to an SSL structure for the connection
2103 pointer to number of bits for cipher
2104 Returns: pointer to allocated string in perm-pool
2108 construct_cipher_name(SSL * ssl, int * bits)
2110 int pool = store_pool;
2111 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2112 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2113 the accessor functions use const in the prototype. */
2115 const uschar * ver = CUS SSL_get_version(ssl);
2116 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2119 SSL_CIPHER_get_bits(c, bits);
2121 store_pool = POOL_PERM;
2122 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2124 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2129 /* Get IETF-standard name for ciphersuite.
2130 Argument: pointer to an SSL structure for the connection
2131 Returns: pointer to string
2134 static const uschar *
2135 cipher_stdname_ssl(SSL * ssl)
2137 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2138 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2140 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2141 return cipher_stdname(id >> 8, id & 0xff);
2147 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2149 /*XXX we might consider a list-of-certs variable for the cert chain.
2150 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2151 in list-handling functions, also consider the difference between the entire
2152 chain and the elements sent by the peer. */
2154 tlsp->peerdn = NULL;
2156 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2157 if (!tlsp->peercert)
2158 tlsp->peercert = SSL_get_peer_certificate(ssl);
2159 /* Beware anonymous ciphers which lead to server_cert being NULL */
2161 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2162 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2165 int oldpool = store_pool;
2167 peerdn[siz-1] = '\0'; /* paranoia */
2168 store_pool = POOL_PERM;
2169 tlsp->peerdn = string_copy(peerdn);
2170 store_pool = oldpool;
2172 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2173 but they don't get called on session-resumption. So use the official
2174 interface, which uses the resumed value. Unfortunately this claims verified
2175 when it actually failed but we're in try-verify mode, due to us wanting the
2176 knowlege that it failed so needing to have the callback and forcing a
2177 permissive return. If we don't force it, the TLS startup is failed.
2178 The extra bit of information is set in verify_override in the cb, stashed
2179 for resumption next to the TLS session, and used here. */
2181 if (!tlsp->verify_override)
2182 tlsp->certificate_verified = SSL_get_verify_result(ssl) == X509_V_OK;
2190 /*************************************************
2191 * Set up for verifying certificates *
2192 *************************************************/
2194 #ifndef DISABLE_OCSP
2195 /* Load certs from file, return TRUE on success */
2198 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
2203 while (sk_X509_num(verify_stack) > 0)
2204 X509_free(sk_X509_pop(verify_stack));
2206 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2207 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
2208 sk_X509_push(verify_stack, x);
2216 /* Called by both client and server startup; on the server possibly
2217 repeated after a Server Name Indication.
2220 sctx SSL_CTX* to initialise
2221 certs certs file or NULL
2222 crl CRL file or NULL
2223 host NULL in a server; the remote host in a client
2224 optional TRUE if called from a server for a host in tls_try_verify_hosts;
2225 otherwise passed as FALSE
2226 cert_vfy_cb Callback function for certificate verification
2227 errstr error string pointer
2229 Returns: OK/DEFER/FAIL
2233 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
2234 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
2236 uschar *expcerts, *expcrl;
2238 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2240 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2242 if (expcerts && *expcerts)
2244 /* Tell the library to use its compiled-in location for the system default
2245 CA bundle. Then add the ones specified in the config, if any. */
2247 if (!SSL_CTX_set_default_verify_paths(sctx))
2248 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2250 if (Ustrcmp(expcerts, "system") != 0)
2252 struct stat statbuf;
2254 if (Ustat(expcerts, &statbuf) < 0)
2256 log_write(0, LOG_MAIN|LOG_PANIC,
2257 "failed to stat %s for certificates", expcerts);
2263 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2264 { file = NULL; dir = expcerts; }
2267 file = expcerts; dir = NULL;
2268 #ifndef DISABLE_OCSP
2269 /* In the server if we will be offering an OCSP proof, load chain from
2270 file for verifying the OCSP proof at load time. */
2273 && statbuf.st_size > 0
2274 && server_static_cbinfo->u_ocsp.server.file
2275 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
2278 log_write(0, LOG_MAIN|LOG_PANIC,
2279 "failed to load cert chain from %s", file);
2285 /* If a certificate file is empty, the next function fails with an
2286 unhelpful error message. If we skip it, we get the correct behaviour (no
2287 certificates are recognized, but the error message is still misleading (it
2288 says no certificate was supplied). But this is better. */
2290 if ( (!file || statbuf.st_size > 0)
2291 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2292 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
2294 /* Load the list of CAs for which we will accept certs, for sending
2295 to the client. This is only for the one-file tls_verify_certificates
2297 If a list isn't loaded into the server, but some verify locations are set,
2298 the server end appears to make a wildcard request for client certs.
2299 Meanwhile, the client library as default behaviour *ignores* the list
2300 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2301 Because of this, and that the dir variant is likely only used for
2302 the public-CA bundle (not for a private CA), not worth fixing. */
2306 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2308 SSL_CTX_set_client_CA_list(sctx, names);
2309 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
2310 sk_X509_NAME_num(names));
2315 /* Handle a certificate revocation list. */
2317 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2319 /* This bit of code is now the version supplied by Lars Mainka. (I have
2320 merely reformatted it into the Exim code style.)
2322 "From here I changed the code to add support for multiple crl's
2323 in pem format in one file or to support hashed directory entries in
2324 pem format instead of a file. This method now uses the library function
2325 X509_STORE_load_locations to add the CRL location to the SSL context.
2326 OpenSSL will then handle the verify against CA certs and CRLs by
2327 itself in the verify callback." */
2329 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
2330 if (expcrl && *expcrl)
2332 struct stat statbufcrl;
2333 if (Ustat(expcrl, &statbufcrl) < 0)
2335 log_write(0, LOG_MAIN|LOG_PANIC,
2336 "failed to stat %s for certificates revocation lists", expcrl);
2341 /* is it a file or directory? */
2343 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
2344 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
2348 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
2354 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
2356 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
2357 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
2359 /* setting the flags to check against the complete crl chain */
2361 X509_STORE_set_flags(cvstore,
2362 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
2366 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2368 /* If verification is optional, don't fail if no certificate */
2370 SSL_CTX_set_verify(sctx,
2371 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2380 /*************************************************
2381 * Start a TLS session in a server *
2382 *************************************************/
2384 /* This is called when Exim is running as a server, after having received
2385 the STARTTLS command. It must respond to that command, and then negotiate
2389 require_ciphers allowed ciphers
2390 errstr pointer to error message
2392 Returns: OK on success
2393 DEFER for errors before the start of the negotiation
2394 FAIL for errors during the negotiation; the server can't
2399 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2402 uschar * expciphers;
2403 tls_ext_ctx_cb * cbinfo;
2404 static uschar peerdn[256];
2406 /* Check for previous activation */
2408 if (tls_in.active.sock >= 0)
2410 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
2411 smtp_printf("554 Already in TLS\r\n", FALSE);
2415 /* Initialize the SSL library. If it fails, it will already have logged
2418 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
2419 #ifndef DISABLE_OCSP
2420 tls_ocsp_file, /*XXX stack*/
2422 NULL, &server_static_cbinfo, &tls_in, errstr);
2423 if (rc != OK) return rc;
2424 cbinfo = server_static_cbinfo;
2426 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2429 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2430 were historically separated by underscores. So that I can use either form in my
2431 tests, and also for general convenience, we turn underscores into hyphens here.
2433 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2434 for TLS 1.3 . Since we do not call it at present we get the default list:
2435 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2440 for (uschar * s = expciphers; *s; s++ ) if (*s == '_') *s = '-';
2441 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2442 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2443 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2444 cbinfo->server_cipher_list = expciphers;
2447 /* If this is a host for which certificate verification is mandatory or
2448 optional, set up appropriately. */
2450 tls_in.certificate_verified = FALSE;
2452 tls_in.dane_verified = FALSE;
2454 server_verify_callback_called = FALSE;
2456 if (verify_check_host(&tls_verify_hosts) == OK)
2458 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2459 FALSE, verify_callback_server, errstr);
2460 if (rc != OK) return rc;
2461 server_verify_optional = FALSE;
2463 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2465 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2466 TRUE, verify_callback_server, errstr);
2467 if (rc != OK) return rc;
2468 server_verify_optional = TRUE;
2471 #ifdef EXPERIMENTAL_TLS_RESUME
2472 SSL_CTX_set_tlsext_ticket_key_cb(server_ctx, ticket_key_callback);
2473 /* despite working, appears to always return failure, so ignoring */
2475 #ifdef OPENSSL_HAVE_NUM_TICKETS
2476 # ifdef EXPERIMENTAL_TLS_RESUME
2477 SSL_CTX_set_num_tickets(server_ctx, tls_in.host_resumable ? 1 : 0);
2479 SSL_CTX_set_num_tickets(server_ctx, 0); /* send no TLS1.3 stateful-tickets */
2484 /* Prepare for new connection */
2486 if (!(server_ssl = SSL_new(server_ctx)))
2487 return tls_error(US"SSL_new", NULL, NULL, errstr);
2489 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2491 * With the SSL_clear(), we get strange interoperability bugs with
2492 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2493 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2495 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2496 * session shutdown. In this case, we have a brand new object and there's no
2497 * obvious reason to immediately clear it. I'm guessing that this was
2498 * originally added because of incomplete initialisation which the clear fixed,
2499 * in some historic release.
2502 /* Set context and tell client to go ahead, except in the case of TLS startup
2503 on connection, where outputting anything now upsets the clients and tends to
2504 make them disconnect. We need to have an explicit fflush() here, to force out
2505 the response. Other smtp_printf() calls do not need it, because in non-TLS
2506 mode, the fflush() happens when smtp_getc() is called. */
2508 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2509 if (!tls_in.on_connect)
2511 smtp_printf("220 TLS go ahead\r\n", FALSE);
2515 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2516 that the OpenSSL library doesn't. */
2518 SSL_set_wfd(server_ssl, fileno(smtp_out));
2519 SSL_set_rfd(server_ssl, fileno(smtp_in));
2520 SSL_set_accept_state(server_ssl);
2522 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2524 sigalrm_seen = FALSE;
2525 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2526 rc = SSL_accept(server_ssl);
2531 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2535 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2536 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
2537 anon-authentication ciphersuite negotiated. */
2539 #ifdef EXPERIMENTAL_TLS_RESUME
2540 if (SSL_session_reused(server_ssl))
2542 tls_in.resumption |= RESUME_USED;
2543 DEBUG(D_tls) debug_printf("Session reused\n");
2547 /* TLS has been set up. Adjust the input functions to read via TLS,
2548 and initialize things. */
2550 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2552 tls_in.cipher = construct_cipher_name(server_ssl, &tls_in.bits);
2553 tls_in.cipher_stdname = cipher_stdname_ssl(server_ssl);
2558 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)))
2559 debug_printf("Shared ciphers: %s\n", buf);
2561 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
2563 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2564 SSL_SESSION_print_keylog(bp, SSL_get_session(server_ssl));
2569 #ifdef EXIM_HAVE_SESSION_TICKET
2571 SSL_SESSION * ss = SSL_get_session(server_ssl);
2572 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
2573 debug_printf("The session has a ticket, life %lu seconds\n",
2574 SSL_SESSION_get_ticket_lifetime_hint(ss));
2579 /* Record the certificate we presented */
2581 X509 * crt = SSL_get_certificate(server_ssl);
2582 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2585 /* Only used by the server-side tls (tls_in), including tls_getc.
2586 Client-side (tls_out) reads (seem to?) go via
2587 smtp_read_response()/ip_recv().
2588 Hence no need to duplicate for _in and _out.
2590 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2591 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2592 ssl_xfer_eof = ssl_xfer_error = FALSE;
2594 receive_getc = tls_getc;
2595 receive_getbuf = tls_getbuf;
2596 receive_get_cache = tls_get_cache;
2597 receive_ungetc = tls_ungetc;
2598 receive_feof = tls_feof;
2599 receive_ferror = tls_ferror;
2600 receive_smtp_buffered = tls_smtp_buffered;
2602 tls_in.active.sock = fileno(smtp_out);
2603 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
2611 tls_client_basic_ctx_init(SSL_CTX * ctx,
2612 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2616 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2617 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2618 the specified host patterns if one of them is defined */
2620 if ( ( !ob->tls_verify_hosts
2621 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2623 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2625 client_verify_optional = FALSE;
2626 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2627 client_verify_optional = TRUE;
2631 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2632 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2636 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2638 cbinfo->verify_cert_hostnames =
2640 string_domain_utf8_to_alabel(host->name, NULL);
2644 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2645 cbinfo->verify_cert_hostnames);
2653 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2656 const char * hostnames[2] = { CS host->name, NULL };
2659 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2660 return tls_error(US"hostnames load", host, NULL, errstr);
2662 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2663 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2664 ) if (rr->type == T_TLSA && rr->size > 3)
2666 const uschar * p = rr->data;
2667 uint8_t usage, selector, mtype;
2668 const char * mdname;
2672 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2673 if (usage != 2 && usage != 3) continue;
2680 default: continue; /* Only match-types 0, 1, 2 are supported */
2681 case 0: mdname = NULL; break;
2682 case 1: mdname = "sha256"; break;
2683 case 2: mdname = "sha512"; break;
2687 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2690 return tls_error(US"tlsa load", host, NULL, errstr);
2691 case 0: /* action not taken */
2695 tls_out.tlsa_usage |= 1<<usage;
2701 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2704 #endif /*SUPPORT_DANE*/
2708 #ifdef EXPERIMENTAL_TLS_RESUME
2709 /* On the client, get any stashed session for the given IP from hints db
2710 and apply it to the ssl-connection for attempted resumption. */
2713 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
2715 tlsp->resumption |= RESUME_SUPPORTED;
2716 if (tlsp->host_resumable)
2718 dbdata_tls_session * dt;
2720 open_db dbblock, * dbm_file;
2722 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2723 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
2724 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
2726 /* key for the db is the IP */
2727 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
2729 SSL_SESSION * ss = NULL;
2730 const uschar * sess_asn1 = dt->session;
2732 len -= sizeof(dbdata_tls_session);
2733 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
2737 ERR_error_string_n(ERR_get_error(),
2738 ssl_errstring, sizeof(ssl_errstring));
2739 debug_printf("decoding session: %s\n", ssl_errstring);
2742 else if ( SSL_SESSION_get_ticket_lifetime_hint(ss) + dt->time_stamp
2745 DEBUG(D_tls) debug_printf("session expired\n");
2746 dbfn_delete(dbm_file, key);
2748 else if (!SSL_set_session(ssl, ss))
2752 ERR_error_string_n(ERR_get_error(),
2753 ssl_errstring, sizeof(ssl_errstring));
2754 debug_printf("applying session to ssl: %s\n", ssl_errstring);
2759 DEBUG(D_tls) debug_printf("good session\n");
2760 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2761 tlsp->verify_override = dt->verify_override;
2765 DEBUG(D_tls) debug_printf("no session record\n");
2766 dbfn_close(dbm_file);
2772 /* On the client, save the session for later resumption */
2775 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
2777 tls_ext_ctx_cb * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
2780 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
2782 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
2784 # ifdef OPENSSL_HAVE_NUM_TICKETS
2785 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
2788 int len = i2d_SSL_SESSION(ss, NULL);
2789 int dlen = sizeof(dbdata_tls_session) + len;
2790 dbdata_tls_session * dt = store_get(dlen);
2791 uschar * s = dt->session;
2792 open_db dbblock, * dbm_file;
2794 DEBUG(D_tls) debug_printf("session is resumable\n");
2795 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
2797 dt->verify_override = tlsp->verify_override;
2798 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
2800 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
2802 const uschar * key = cbinfo->host->address;
2803 dbfn_delete(dbm_file, key);
2804 dbfn_write(dbm_file, key, dt, dlen);
2805 dbfn_close(dbm_file);
2806 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
2815 tls_client_ctx_resume_prehandshake(
2816 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
2817 smtp_transport_options_block * ob, host_item * host)
2819 /* Should the client request a session resumption ticket? */
2820 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
2822 tlsp->host_resumable = TRUE;
2824 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
2825 SSL_SESS_CACHE_CLIENT
2826 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
2827 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
2832 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
2833 host_item * host, uschar ** errstr)
2835 if (tlsp->host_resumable)
2838 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
2839 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
2841 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
2842 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_cbinfo))
2844 tls_error(US"set ex_data", host, NULL, errstr);
2847 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_cbinfo);
2850 tlsp->resumption = RESUME_SUPPORTED;
2851 /* Pick up a previous session, saved on an old ticket */
2852 tls_retrieve_session(tlsp, ssl, host->address);
2857 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
2860 if (SSL_session_reused(exim_client_ctx->ssl))
2862 DEBUG(D_tls) debug_printf("The session was reused\n");
2863 tlsp->resumption |= RESUME_USED;
2866 #endif /* EXPERIMENTAL_TLS_RESUME */
2869 /*************************************************
2870 * Start a TLS session in a client *
2871 *************************************************/
2873 /* Called from the smtp transport after STARTTLS has been accepted.
2876 cctx connection context
2877 conn_args connection details
2878 cookie datum for randomness; can be NULL
2879 tlsp record details of TLS channel configuration here; must be non-NULL
2880 errstr error string pointer
2882 Returns: TRUE for success with TLS session context set in connection context,
2887 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
2888 void * cookie, tls_support * tlsp, uschar ** errstr)
2890 host_item * host = conn_args->host; /* for msgs and option-tests */
2891 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
2892 smtp_transport_options_block * ob = tb
2893 ? (smtp_transport_options_block *)tb->options_block
2894 : &smtp_transport_option_defaults;
2895 exim_openssl_client_tls_ctx * exim_client_ctx;
2896 uschar * expciphers;
2898 static uschar peerdn[256];
2900 #ifndef DISABLE_OCSP
2901 BOOL request_ocsp = FALSE;
2902 BOOL require_ocsp = FALSE;
2906 store_pool = POOL_PERM;
2907 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx));
2908 exim_client_ctx->corked = NULL;
2912 tlsp->tlsa_usage = 0;
2915 #ifndef DISABLE_OCSP
2917 # ifdef SUPPORT_DANE
2918 if ( conn_args->dane
2919 && ob->hosts_request_ocsp[0] == '*'
2920 && ob->hosts_request_ocsp[1] == '\0'
2923 /* Unchanged from default. Use a safer one under DANE */
2924 request_ocsp = TRUE;
2925 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2926 " {= {4}{$tls_out_tlsa_usage}} } "
2932 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
2933 request_ocsp = TRUE;
2935 # ifdef SUPPORT_DANE
2939 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2943 rc = tls_init(&exim_client_ctx->ctx, host, NULL,
2944 ob->tls_certificate, ob->tls_privatekey,
2945 #ifndef DISABLE_OCSP
2946 (void *)(long)request_ocsp,
2948 cookie, &client_static_cbinfo, tlsp, errstr);
2949 if (rc != OK) return FALSE;
2951 tlsp->certificate_verified = FALSE;
2952 client_verify_callback_called = FALSE;
2956 if (conn_args->dane)
2958 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2959 other failures should be treated as problems. */
2960 if (ob->dane_require_tls_ciphers &&
2961 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2962 &expciphers, errstr))
2964 if (expciphers && *expciphers == '\0')
2969 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2970 &expciphers, errstr))
2973 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2974 are separated by underscores. So that I can use either form in my tests, and
2975 also for general convenience, we turn underscores into hyphens here. */
2979 uschar *s = expciphers;
2980 while (*s) { if (*s == '_') *s = '-'; s++; }
2981 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2982 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
2984 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
2990 if (conn_args->dane)
2992 SSL_CTX_set_verify(exim_client_ctx->ctx,
2993 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2994 verify_callback_client_dane);
2996 if (!DANESSL_library_init())
2998 tls_error(US"library init", host, NULL, errstr);
3001 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3003 tls_error(US"context init", host, NULL, errstr);
3011 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3012 client_static_cbinfo, errstr) != OK)
3015 #ifdef EXPERIMENTAL_TLS_RESUME
3016 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3020 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3022 tls_error(US"SSL_new", host, NULL, errstr);
3025 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3027 #ifdef EXPERIMENTAL_TLS_RESUME
3028 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3033 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3034 SSL_set_connect_state(exim_client_ctx->ssl);
3038 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3042 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3044 else if (!Ustrlen(tlsp->sni))
3048 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3049 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3050 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3052 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3059 if (conn_args->dane)
3060 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3064 #ifndef DISABLE_OCSP
3065 /* Request certificate status at connection-time. If the server
3066 does OCSP stapling we will get the callback (set in tls_init()) */
3067 # ifdef SUPPORT_DANE
3071 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3072 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3074 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3075 this means we avoid the OCSP request, we wasted the setup
3076 cost in tls_init(). */
3077 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3078 request_ocsp = require_ocsp
3079 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3086 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3087 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
3088 tlsp->ocsp = OCSP_NOT_RESP;
3092 #ifndef DISABLE_EVENT
3093 client_static_cbinfo->event_action = tb ? tb->event_action : NULL;
3096 /* There doesn't seem to be a built-in timeout on connection. */
3098 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3099 sigalrm_seen = FALSE;
3100 ALARM(ob->command_timeout);
3101 rc = SSL_connect(exim_client_ctx->ssl);
3105 if (conn_args->dane)
3106 DANESSL_cleanup(exim_client_ctx->ssl);
3111 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
3117 debug_printf("SSL_connect succeeded\n");
3118 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3120 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3121 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
3127 #ifdef EXPERIMENTAL_TLS_RESUME
3128 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
3131 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
3133 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, &tlsp->bits);
3134 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
3136 /* Record the certificate we presented */
3138 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
3139 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
3142 tlsp->active.sock = cctx->sock;
3143 tlsp->active.tls_ctx = exim_client_ctx;
3144 cctx->tls_ctx = exim_client_ctx;
3153 tls_refill(unsigned lim)
3158 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
3159 ssl_xfer_buffer, ssl_xfer_buffer_size);
3161 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3162 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
3163 MIN(ssl_xfer_buffer_size, lim));
3164 error = SSL_get_error(server_ssl, inbytes);
3165 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3167 if (had_command_timeout) /* set by signal handler */
3168 smtp_command_timeout_exit(); /* does not return */
3169 if (had_command_sigterm)
3170 smtp_command_sigterm_exit();
3171 if (had_data_timeout)
3172 smtp_data_timeout_exit();
3173 if (had_data_sigint)
3174 smtp_data_sigint_exit();
3176 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3177 closed down, not that the socket itself has been closed down. Revert to
3178 non-SSL handling. */
3182 case SSL_ERROR_NONE:
3185 case SSL_ERROR_ZERO_RETURN:
3186 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3188 receive_getc = smtp_getc;
3189 receive_getbuf = smtp_getbuf;
3190 receive_get_cache = smtp_get_cache;
3191 receive_ungetc = smtp_ungetc;
3192 receive_feof = smtp_feof;
3193 receive_ferror = smtp_ferror;
3194 receive_smtp_buffered = smtp_buffered;
3196 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
3197 SSL_shutdown(server_ssl);
3199 #ifndef DISABLE_OCSP
3200 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
3201 server_static_cbinfo->verify_stack = NULL;
3203 SSL_free(server_ssl);
3204 SSL_CTX_free(server_ctx);
3207 tls_in.active.sock = -1;
3208 tls_in.active.tls_ctx = NULL;
3210 tls_in.cipher = NULL;
3211 tls_in.peerdn = NULL;
3216 /* Handle genuine errors */
3218 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3219 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
3220 ssl_xfer_error = TRUE;
3224 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3225 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
3226 debug_printf(" - syscall %s\n", strerror(errno));
3227 ssl_xfer_error = TRUE;
3231 #ifndef DISABLE_DKIM
3232 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
3234 ssl_xfer_buffer_hwm = inbytes;
3235 ssl_xfer_buffer_lwm = 0;
3240 /*************************************************
3241 * TLS version of getc *
3242 *************************************************/
3244 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3245 it refills the buffer via the SSL reading function.
3247 Arguments: lim Maximum amount to read/buffer
3248 Returns: the next character or EOF
3250 Only used by the server-side TLS.
3254 tls_getc(unsigned lim)
3256 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3257 if (!tls_refill(lim))
3258 return ssl_xfer_error ? EOF : smtp_getc(lim);
3260 /* Something in the buffer; return next uschar */
3262 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
3266 tls_getbuf(unsigned * len)
3271 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3272 if (!tls_refill(*len))
3274 if (!ssl_xfer_error) return smtp_getbuf(len);
3279 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
3281 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
3282 ssl_xfer_buffer_lwm += size;
3291 #ifndef DISABLE_DKIM
3292 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
3294 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
3300 tls_could_read(void)
3302 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
3306 /*************************************************
3307 * Read bytes from TLS channel *
3308 *************************************************/
3312 ct_ctx client context pointer, or NULL for the one global server context
3316 Returns: the number of bytes read
3317 -1 after a failed read, including EOF
3319 Only used by the client-side TLS.
3323 tls_read(void * ct_ctx, uschar *buff, size_t len)
3325 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3329 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3330 buff, (unsigned int)len);
3332 inbytes = SSL_read(ssl, CS buff, len);
3333 error = SSL_get_error(ssl, inbytes);
3335 if (error == SSL_ERROR_ZERO_RETURN)
3337 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3340 else if (error != SSL_ERROR_NONE)
3350 /*************************************************
3351 * Write bytes down TLS channel *
3352 *************************************************/
3356 ct_ctx client context pointer, or NULL for the one global server context
3359 more further data expected soon
3361 Returns: the number of bytes after a successful write,
3362 -1 after a failed write
3364 Used by both server-side and client-side TLS.
3368 tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more)
3371 int outbytes, error;
3373 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3374 static gstring * server_corked = NULL;
3375 gstring ** corkedp = ct_ctx
3376 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
3377 gstring * corked = *corkedp;
3379 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
3380 buff, (unsigned long)len, more ? ", more" : "");
3382 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
3383 "more" is notified. This hack is only ok if small amounts are involved AND only
3384 one stream does it, in one context (i.e. no store reset). Currently it is used
3385 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
3386 We support callouts done by the server process by using a separate client
3387 context for the stashed information. */
3388 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
3389 a store reset there, so use POOL_PERM. */
3390 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
3392 if ((more || corked))
3394 #ifdef EXPERIMENTAL_PIPE_CONNECT
3395 int save_pool = store_pool;
3396 store_pool = POOL_PERM;
3399 corked = string_catn(corked, buff, len);
3401 #ifdef EXPERIMENTAL_PIPE_CONNECT
3402 store_pool = save_pool;
3410 buff = CUS corked->s;
3415 for (int left = len; left > 0;)
3417 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
3418 outbytes = SSL_write(ssl, CS buff, left);
3419 error = SSL_get_error(ssl, outbytes);
3420 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
3424 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3425 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
3428 case SSL_ERROR_NONE:
3433 case SSL_ERROR_ZERO_RETURN:
3434 log_write(0, LOG_MAIN, "SSL channel closed on write");
3437 case SSL_ERROR_SYSCALL:
3438 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
3439 sender_fullhost ? sender_fullhost : US"<unknown>",
3444 log_write(0, LOG_MAIN, "SSL_write error %d", error);
3453 /*************************************************
3454 * Close down a TLS session *
3455 *************************************************/
3457 /* This is also called from within a delivery subprocess forked from the
3458 daemon, to shut down the TLS library, without actually doing a shutdown (which
3459 would tamper with the SSL session in the parent process).
3462 ct_ctx client TLS context pointer, or NULL for the one global server context
3463 shutdown 1 if TLS close-alert is to be sent,
3464 2 if also response to be waited for
3468 Used by both server-side and client-side TLS.
3472 tls_close(void * ct_ctx, int shutdown)
3474 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
3475 SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx;
3476 SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl;
3477 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
3479 if (*fdp < 0) return; /* TLS was not active */
3484 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3485 shutdown > 1 ? " (with response-wait)" : "");
3487 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
3491 rc = SSL_shutdown(*sslp); /* wait for response */
3495 if (rc < 0) DEBUG(D_tls)
3497 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3498 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
3502 #ifndef DISABLE_OCSP
3503 if (!o_ctx) /* server side */
3505 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
3506 server_static_cbinfo->verify_stack = NULL;
3510 SSL_CTX_free(*ctxp);
3520 /*************************************************
3521 * Let tls_require_ciphers be checked at startup *
3522 *************************************************/
3524 /* The tls_require_ciphers option, if set, must be something which the
3527 Returns: NULL on success, or error message
3531 tls_validate_require_cipher(void)
3534 uschar *s, *expciphers, *err;
3536 /* this duplicates from tls_init(), we need a better "init just global
3537 state, for no specific purpose" singleton function of our own */
3539 #ifdef EXIM_NEED_OPENSSL_INIT
3540 SSL_load_error_strings();
3541 OpenSSL_add_ssl_algorithms();
3543 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
3544 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
3545 list of available digests. */
3546 EVP_add_digest(EVP_sha256());
3549 if (!(tls_require_ciphers && *tls_require_ciphers))
3552 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3554 return US"failed to expand tls_require_ciphers";
3556 if (!(expciphers && *expciphers))
3559 /* normalisation ripped from above */
3561 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
3565 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3566 if (!(ctx = SSL_CTX_new(TLS_server_method())))
3568 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
3571 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3572 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
3576 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3578 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
3580 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3581 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3582 expciphers, ssl_errstring);
3593 /*************************************************
3594 * Report the library versions. *
3595 *************************************************/
3597 /* There have historically been some issues with binary compatibility in
3598 OpenSSL libraries; if Exim (like many other applications) is built against
3599 one version of OpenSSL but the run-time linker picks up another version,
3600 it can result in serious failures, including crashing with a SIGSEGV. So
3601 report the version found by the compiler and the run-time version.
3603 Note: some OS vendors backport security fixes without changing the version
3604 number/string, and the version date remains unchanged. The _build_ date
3605 will change, so we can more usefully assist with version diagnosis by also
3606 reporting the build date.
3608 Arguments: a FILE* to print the results to
3613 tls_version_report(FILE *f)
3615 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
3618 OPENSSL_VERSION_TEXT,
3619 SSLeay_version(SSLEAY_VERSION),
3620 SSLeay_version(SSLEAY_BUILT_ON));
3621 /* third line is 38 characters for the %s and the line is 73 chars long;
3622 the OpenSSL output includes a "built on: " prefix already. */
3628 /*************************************************
3629 * Random number generation *
3630 *************************************************/
3632 /* Pseudo-random number generation. The result is not expected to be
3633 cryptographically strong but not so weak that someone will shoot themselves
3634 in the foot using it as a nonce in input in some email header scheme or
3635 whatever weirdness they'll twist this into. The result should handle fork()
3636 and avoid repeating sequences. OpenSSL handles that for us.
3640 Returns a random number in range [0, max-1]
3644 vaguely_random_number(int max)
3648 static pid_t pidlast = 0;
3650 uschar smallbuf[sizeof(r)];
3656 if (pidnow != pidlast)
3658 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3659 is unique for each thread", this doesn't apparently apply across processes,
3660 so our own warning from vaguely_random_number_fallback() applies here too.
3661 Fix per PostgreSQL. */
3667 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3671 gettimeofday(&r.tv, NULL);
3674 RAND_seed(US (&r), sizeof(r));
3676 /* We're after pseudo-random, not random; if we still don't have enough data
3677 in the internal PRNG then our options are limited. We could sleep and hope
3678 for entropy to come along (prayer technique) but if the system is so depleted
3679 in the first place then something is likely to just keep taking it. Instead,
3680 we'll just take whatever little bit of pseudo-random we can still manage to
3683 needed_len = sizeof(r);
3684 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3685 asked for a number less than 10. */
3686 for (r = max, i = 0; r; ++i)
3692 #ifdef EXIM_HAVE_RAND_PSEUDO
3693 /* We do not care if crypto-strong */
3694 i = RAND_pseudo_bytes(smallbuf, needed_len);
3696 i = RAND_bytes(smallbuf, needed_len);
3702 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3703 return vaguely_random_number_fallback(max);
3707 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3710 /* We don't particularly care about weighted results; if someone wants
3711 smooth distribution and cares enough then they should submit a patch then. */
3718 /*************************************************
3719 * OpenSSL option parse *
3720 *************************************************/
3722 /* Parse one option for tls_openssl_options_parse below
3725 name one option name
3726 value place to store a value for it
3727 Returns success or failure in parsing
3733 tls_openssl_one_option_parse(uschar *name, long *value)
3736 int last = exim_openssl_options_size;
3737 while (last > first)
3739 int middle = (first + last)/2;
3740 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3743 *value = exim_openssl_options[middle].value;
3757 /*************************************************
3758 * OpenSSL option parsing logic *
3759 *************************************************/
3761 /* OpenSSL has a number of compatibility options which an administrator might
3762 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3763 we look like log_selector.
3766 option_spec the administrator-supplied string of options
3767 results ptr to long storage for the options bitmap
3768 Returns success or failure
3772 tls_openssl_options_parse(uschar *option_spec, long *results)
3777 BOOL adding, item_parsed;
3779 /* Server: send no (<= TLS1.2) session tickets */
3780 result = SSL_OP_NO_TICKET;
3782 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3783 * from default because it increases BEAST susceptibility. */
3784 #ifdef SSL_OP_NO_SSLv2
3785 result |= SSL_OP_NO_SSLv2;
3787 #ifdef SSL_OP_NO_SSLv3
3788 result |= SSL_OP_NO_SSLv3;
3790 #ifdef SSL_OP_SINGLE_DH_USE
3791 result |= SSL_OP_SINGLE_DH_USE;
3800 for (uschar * s = option_spec; *s; /**/)
3802 while (isspace(*s)) ++s;
3805 if (*s != '+' && *s != '-')
3807 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3808 "+ or - expected but found \"%s\"\n", s);
3811 adding = *s++ == '+';
3812 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3815 item_parsed = tls_openssl_one_option_parse(s, &item);
3819 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3822 DEBUG(D_tls) debug_printf("openssl option, %s %8lx: %lx (%s)\n",
3823 adding ? "adding to " : "removing from", result, item, s);
3835 #endif /*!MACRO_PREDEF*/
3838 /* End of tls-openssl.c */