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 = 3600;
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 if (preverify_ok == 0)
591 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
592 *verify_mode, sender_host_address)
594 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
595 tlsp == &tls_out ? deliver_host_address : sender_host_address,
597 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
602 tlsp->peercert = X509_dup(cert); /* record failing cert */
603 return 0; /* reject */
605 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
606 "tls_try_verify_hosts)\n");
607 tlsp->verify_override = TRUE;
612 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
614 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
615 { /* client, wanting stapling */
616 /* Add the server cert's signing chain as the one
617 for the verification of the OCSP stapled information. */
619 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
622 sk_X509_push(client_static_cbinfo->verify_stack, cert);
625 #ifndef DISABLE_EVENT
626 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
627 return 0; /* reject, with peercert set */
632 const uschar * verify_cert_hostnames;
634 if ( tlsp == &tls_out
635 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
636 /* client, wanting hostname check */
639 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
640 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
641 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
643 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
644 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
647 const uschar * list = verify_cert_hostnames;
650 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
651 if ((rc = X509_check_host(cert, CCS name, 0,
652 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
653 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
658 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
659 tlsp == &tls_out ? deliver_host_address : sender_host_address);
666 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
669 uschar * extra = verify_mode
670 ? string_sprintf(" (during %c-verify for [%s])",
671 *verify_mode, sender_host_address)
673 log_write(0, LOG_MAIN,
674 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
675 tlsp == &tls_out ? deliver_host_address : sender_host_address,
676 extra, dn, verify_cert_hostnames);
681 tlsp->peercert = X509_dup(cert); /* record failing cert */
682 return 0; /* reject */
684 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
685 "tls_try_verify_hosts)\n");
686 tlsp->verify_override = TRUE;
690 #ifndef DISABLE_EVENT
691 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
692 return 0; /* reject, with peercert set */
695 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
696 *calledp ? "" : " authenticated", dn);
700 return 1; /* accept, at least for this level */
704 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
706 return verify_callback(preverify_ok, x509ctx, &tls_out,
707 &client_verify_callback_called, &client_verify_optional);
711 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
713 return verify_callback(preverify_ok, x509ctx, &tls_in,
714 &server_verify_callback_called, &server_verify_optional);
720 /* This gets called *by* the dane library verify callback, which interposes
724 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
726 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
728 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
729 #ifndef DISABLE_EVENT
730 BOOL dummy_called, optional = FALSE;
733 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
735 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
736 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
737 deliver_host_address);
740 dn[sizeof(dn)-1] = '\0';
742 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
743 preverify_ok ? "ok":"BAD", depth, dn);
745 #ifndef DISABLE_EVENT
746 if (verify_event(&tls_out, cert, depth, dn,
747 &dummy_called, &optional, US"DANE"))
748 return 0; /* reject, with peercert set */
751 if (preverify_ok == 1)
753 tls_out.dane_verified = TRUE;
755 if (client_static_cbinfo->u_ocsp.client.verify_store)
756 { /* client, wanting stapling */
757 /* Add the server cert's signing chain as the one
758 for the verification of the OCSP stapled information. */
760 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
763 sk_X509_push(client_static_cbinfo->verify_stack, cert);
769 int err = X509_STORE_CTX_get_error(x509ctx);
771 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
772 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
778 #endif /*SUPPORT_DANE*/
781 /*************************************************
782 * Information callback *
783 *************************************************/
785 /* The SSL library functions call this from time to time to indicate what they
786 are doing. We copy the string to the debugging output when TLS debugging has
798 info_callback(SSL *s, int where, int ret)
804 if (where & SSL_ST_CONNECT)
805 str = US"SSL_connect";
806 else if (where & SSL_ST_ACCEPT)
807 str = US"SSL_accept";
809 str = US"SSL info (undefined)";
811 if (where & SSL_CB_LOOP)
812 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
813 else if (where & SSL_CB_ALERT)
814 debug_printf("SSL3 alert %s:%s:%s\n",
815 str = where & SSL_CB_READ ? US"read" : US"write",
816 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
817 else if (where & SSL_CB_EXIT)
819 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
821 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
822 else if (where & SSL_CB_HANDSHAKE_START)
823 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
824 else if (where & SSL_CB_HANDSHAKE_DONE)
825 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
829 #ifdef OPENSSL_HAVE_KEYLOG_CB
831 keylog_callback(const SSL *ssl, const char *line)
833 DEBUG(D_tls) debug_printf("%.200s\n", line);
838 #ifdef EXPERIMENTAL_TLS_RESUME
839 /* Manage the keysets used for encrypting the session tickets, on the server. */
841 typedef struct { /* Session ticket encryption key */
844 const EVP_CIPHER * aes_cipher;
845 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
846 const EVP_MD * hmac_hash;
852 static exim_stek exim_tk; /* current key */
853 static exim_stek exim_tk_old; /* previous key */
858 time_t t = time(NULL);
862 if (exim_tk.renew >= t) return;
863 exim_tk_old = exim_tk;
866 if (f.running_in_test_harness) ssl_session_timeout = 6;
868 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
869 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
870 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
871 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
873 exim_tk.name[0] = 'E';
874 exim_tk.aes_cipher = EVP_aes_256_cbc();
875 exim_tk.hmac_hash = EVP_sha256();
876 exim_tk.expire = t + ssl_session_timeout;
877 exim_tk.renew = t + ssl_session_timeout/2;
883 if (!exim_tk.name[0]) return NULL;
888 tk_find(const uschar * name)
890 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
891 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
895 /* Callback for session tickets, on server */
897 ticket_key_callback(SSL * ssl, uschar key_name[16],
898 uschar * iv, EVP_CIPHER_CTX * ctx, HMAC_CTX * hctx, int enc)
900 tls_support * tlsp = server_static_cbinfo->tlsp;
905 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
906 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
908 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
909 return -1; /* insufficient random */
911 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
912 return 0; /* key couldn't be created */
913 memcpy(key_name, key->name, 16);
914 DEBUG(D_tls) debug_printf("STEK expire %ld\n", key->expire - time(NULL));
916 /*XXX will want these dependent on the ssl session strength */
917 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
918 key->hmac_hash, NULL);
919 EVP_EncryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
921 DEBUG(D_tls) debug_printf("ticket created\n");
926 time_t now = time(NULL);
928 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
929 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
931 if (!(key = tk_find(key_name)) || key->expire < now)
935 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
936 if (key) debug_printf("STEK expire %ld\n", key->expire - now);
941 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
942 key->hmac_hash, NULL);
943 EVP_DecryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
945 DEBUG(D_tls) debug_printf("ticket usable, STEK expire %ld\n", key->expire - now);
946 return key->renew < now ? 2 : 1;
953 /*************************************************
954 * Initialize for DH *
955 *************************************************/
957 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
960 sctx The current SSL CTX (inbound or outbound)
961 dhparam DH parameter file or fixed parameter identity string
962 host connected host, if client; NULL if server
963 errstr error string pointer
965 Returns: TRUE if OK (nothing to set up, or setup worked)
969 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
977 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
980 if (!dhexpanded || !*dhexpanded)
981 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
982 else if (dhexpanded[0] == '/')
984 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
986 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
987 host, US strerror(errno), errstr);
993 if (Ustrcmp(dhexpanded, "none") == 0)
995 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
999 if (!(pem = std_dh_prime_named(dhexpanded)))
1001 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
1002 host, US strerror(errno), errstr);
1005 bio = BIO_new_mem_buf(CS pem, -1);
1008 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
1011 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
1012 host, NULL, errstr);
1016 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
1017 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
1018 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
1019 * If someone wants to dance at the edge, then they can raise the limit or use
1020 * current libraries. */
1021 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
1022 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
1023 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
1024 dh_bitsize = DH_bits(dh);
1026 dh_bitsize = 8 * DH_size(dh);
1029 /* Even if it is larger, we silently return success rather than cause things
1030 * to fail out, so that a too-large DH will not knock out all TLS; it's a
1031 * debatable choice. */
1032 if (dh_bitsize > tls_dh_max_bits)
1035 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
1036 dh_bitsize, tls_dh_max_bits);
1040 SSL_CTX_set_tmp_dh(sctx, dh);
1042 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
1043 dhexpanded ? dhexpanded : US"default", dh_bitsize);
1055 /*************************************************
1056 * Initialize for ECDH *
1057 *************************************************/
1059 /* Load parameters for ECDH encryption.
1061 For now, we stick to NIST P-256 because: it's simple and easy to configure;
1062 it avoids any patent issues that might bite redistributors; despite events in
1063 the news and concerns over curve choices, we're not cryptographers, we're not
1064 pretending to be, and this is "good enough" to be better than no support,
1065 protecting against most adversaries. Given another year or two, there might
1066 be sufficient clarity about a "right" way forward to let us make an informed
1067 decision, instead of a knee-jerk reaction.
1069 Longer-term, we should look at supporting both various named curves and
1070 external files generated with "openssl ecparam", much as we do for init_dh().
1071 We should also support "none" as a value, to explicitly avoid initialisation.
1076 sctx The current SSL CTX (inbound or outbound)
1077 host connected host, if client; NULL if server
1078 errstr error string pointer
1080 Returns: TRUE if OK (nothing to set up, or setup worked)
1084 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
1086 #ifdef OPENSSL_NO_ECDH
1095 if (host) /* No ECDH setup for clients, only for servers */
1098 # ifndef EXIM_HAVE_ECDH
1100 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
1104 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
1106 if (!exp_curve || !*exp_curve)
1109 /* "auto" needs to be handled carefully.
1110 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
1111 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
1112 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
1113 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
1114 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
1116 if (Ustrcmp(exp_curve, "auto") == 0)
1118 #if OPENSSL_VERSION_NUMBER < 0x10002000L
1119 DEBUG(D_tls) debug_printf(
1120 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
1121 exp_curve = US"prime256v1";
1123 # if defined SSL_CTRL_SET_ECDH_AUTO
1124 DEBUG(D_tls) debug_printf(
1125 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
1126 SSL_CTX_set_ecdh_auto(sctx, 1);
1129 DEBUG(D_tls) debug_printf(
1130 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
1136 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
1137 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
1138 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
1139 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
1143 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
1144 host, NULL, errstr);
1148 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
1150 tls_error(US"Unable to create ec curve", host, NULL, errstr);
1154 /* The "tmp" in the name here refers to setting a temporary key
1155 not to the stability of the interface. */
1157 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
1158 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
1160 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
1165 # endif /*EXIM_HAVE_ECDH*/
1166 #endif /*OPENSSL_NO_ECDH*/
1172 #ifndef DISABLE_OCSP
1173 /*************************************************
1174 * Load OCSP information into state *
1175 *************************************************/
1176 /* Called to load the server OCSP response from the given file into memory, once
1177 caller has determined this is needed. Checks validity. Debugs a message
1180 ASSUMES: single response, for single cert.
1183 sctx the SSL_CTX* to update
1184 cbinfo various parts of session state
1185 expanded the filename putatively holding an OCSP response
1190 ocsp_load_response(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo, const uschar *expanded)
1193 OCSP_RESPONSE * resp;
1194 OCSP_BASICRESP * basic_response;
1195 OCSP_SINGLERESP * single_response;
1196 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1197 STACK_OF(X509) * sk;
1198 unsigned long verify_flags;
1199 int status, reason, i;
1201 cbinfo->u_ocsp.server.file_expanded = string_copy(expanded);
1202 if (cbinfo->u_ocsp.server.response)
1204 OCSP_RESPONSE_free(cbinfo->u_ocsp.server.response);
1205 cbinfo->u_ocsp.server.response = NULL;
1208 if (!(bio = BIO_new_file(CS cbinfo->u_ocsp.server.file_expanded, "rb")))
1210 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
1211 cbinfo->u_ocsp.server.file_expanded);
1215 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1219 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
1223 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1225 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1226 OCSP_response_status_str(status), status);
1230 if (!(basic_response = OCSP_response_get1_basic(resp)))
1233 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1237 sk = cbinfo->verify_stack;
1238 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1240 /* May need to expose ability to adjust those flags?
1241 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1242 OCSP_TRUSTOTHER OCSP_NOINTERN */
1244 /* This does a full verify on the OCSP proof before we load it for serving
1245 up; possibly overkill - just date-checks might be nice enough.
1247 OCSP_basic_verify takes a "store" arg, but does not
1248 use it for the chain verification, which is all we do
1249 when OCSP_NOVERIFY is set. The content from the wire
1250 "basic_response" and a cert-stack "sk" are all that is used.
1252 We have a stack, loaded in setup_certs() if tls_verify_certificates
1253 was a file (not a directory, or "system"). It is unfortunate we
1254 cannot used the connection context store, as that would neatly
1255 handle the "system" case too, but there seems to be no library
1256 function for getting a stack from a store.
1257 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1258 We do not free the stack since it could be needed a second time for
1261 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1262 be a public interface into the OpenSSL library (there's no manual entry) -
1263 But what with? We also use OCSP_basic_verify in the client stapling callback.
1264 And there we NEED it; we must verify that status... unless the
1265 library does it for us anyway? */
1267 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1271 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1272 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1277 /* Here's the simplifying assumption: there's only one response, for the
1278 one certificate we use, and nothing for anything else in a chain. If this
1279 proves false, we need to extract a cert id from our issued cert
1280 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1281 right cert in the stack and then calls OCSP_single_get0_status()).
1283 I'm hoping to avoid reworking a bunch more of how we handle state here. */
1285 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1288 debug_printf("Unable to get first response from OCSP basic response.\n");
1292 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1293 if (status != V_OCSP_CERTSTATUS_GOOD)
1295 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1296 OCSP_cert_status_str(status), status,
1297 OCSP_crl_reason_str(reason), reason);
1301 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1303 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1308 cbinfo->u_ocsp.server.response = resp; /*XXX stack?*/
1312 if (f.running_in_test_harness)
1314 extern char ** environ;
1315 if (environ) for (uschar ** p = USS environ; *p; p++)
1316 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1318 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1319 goto supply_response;
1324 #endif /*!DISABLE_OCSP*/
1329 /* Create and install a selfsigned certificate, for use in server mode */
1332 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
1340 where = US"allocating pkey";
1341 if (!(pkey = EVP_PKEY_new()))
1344 where = US"allocating cert";
1345 if (!(x509 = X509_new()))
1348 where = US"generating pkey";
1349 if (!(rsa = rsa_callback(NULL, 0, 2048)))
1352 where = US"assigning pkey";
1353 if (!EVP_PKEY_assign_RSA(pkey, rsa))
1356 X509_set_version(x509, 2); /* N+1 - version 3 */
1357 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
1358 X509_gmtime_adj(X509_get_notBefore(x509), 0);
1359 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1360 X509_set_pubkey(x509, pkey);
1362 name = X509_get_subject_name(x509);
1363 X509_NAME_add_entry_by_txt(name, "C",
1364 MBSTRING_ASC, CUS "UK", -1, -1, 0);
1365 X509_NAME_add_entry_by_txt(name, "O",
1366 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
1367 X509_NAME_add_entry_by_txt(name, "CN",
1368 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
1369 X509_set_issuer_name(x509, name);
1371 where = US"signing cert";
1372 if (!X509_sign(x509, pkey, EVP_md5()))
1375 where = US"installing selfsign cert";
1376 if (!SSL_CTX_use_certificate(sctx, x509))
1379 where = US"installing selfsign key";
1380 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1386 (void) tls_error(where, NULL, NULL, errstr);
1387 if (x509) X509_free(x509);
1388 if (pkey) EVP_PKEY_free(pkey);
1396 tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1399 DEBUG(D_tls) debug_printf("tls_certificate file %s\n", file);
1400 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1401 return tls_error(string_sprintf(
1402 "SSL_CTX_use_certificate_chain_file file=%s", file),
1403 cbinfo->host, NULL, errstr);
1408 tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1411 DEBUG(D_tls) debug_printf("tls_privatekey file %s\n", file);
1412 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1413 return tls_error(string_sprintf(
1414 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1419 /*************************************************
1420 * Expand key and cert file specs *
1421 *************************************************/
1423 /* Called once during tls_init and possibly again during TLS setup, for a
1424 new context, if Server Name Indication was used and tls_sni was seen in
1425 the certificate string.
1428 sctx the SSL_CTX* to update
1429 cbinfo various parts of session state
1430 errstr error string pointer
1432 Returns: OK/DEFER/FAIL
1436 tls_expand_session_files(SSL_CTX *sctx, tls_ext_ctx_cb *cbinfo,
1441 if (!cbinfo->certificate)
1443 if (!cbinfo->is_server) /* client */
1446 if (tls_install_selfsign(sctx, errstr) != OK)
1453 if (Ustrstr(cbinfo->certificate, US"tls_sni") ||
1454 Ustrstr(cbinfo->certificate, US"tls_in_sni") ||
1455 Ustrstr(cbinfo->certificate, US"tls_out_sni")
1457 reexpand_tls_files_for_sni = TRUE;
1459 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
1463 if (cbinfo->is_server)
1465 const uschar * file_list = expanded;
1469 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1470 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1473 else /* would there ever be a need for multiple client certs? */
1474 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1477 if ( cbinfo->privatekey
1478 && !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
1481 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1482 of the expansion is an empty string, ignore it also, and assume the private
1483 key is in the same file as the certificate. */
1485 if (expanded && *expanded)
1486 if (cbinfo->is_server)
1488 const uschar * file_list = expanded;
1492 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1493 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1496 else /* would there ever be a need for multiple client certs? */
1497 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1501 #ifndef DISABLE_OCSP
1502 if (cbinfo->is_server && cbinfo->u_ocsp.server.file)
1505 if (!expand_check(cbinfo->u_ocsp.server.file, US"tls_ocsp_file", &expanded, errstr))
1508 if (expanded && *expanded)
1510 DEBUG(D_tls) debug_printf("tls_ocsp_file %s\n", expanded);
1511 if ( cbinfo->u_ocsp.server.file_expanded
1512 && (Ustrcmp(expanded, cbinfo->u_ocsp.server.file_expanded) == 0))
1514 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1517 ocsp_load_response(sctx, cbinfo, expanded);
1528 /*************************************************
1529 * Callback to handle SNI *
1530 *************************************************/
1532 /* Called when acting as server during the TLS session setup if a Server Name
1533 Indication extension was sent by the client.
1535 API documentation is OpenSSL s_server.c implementation.
1538 s SSL* of the current session
1539 ad unknown (part of OpenSSL API) (unused)
1540 arg Callback of "our" registered data
1542 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1544 XXX might need to change to using ClientHello callback,
1545 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
1548 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1550 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1552 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
1553 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1555 int old_pool = store_pool;
1556 uschar * dummy_errstr;
1559 return SSL_TLSEXT_ERR_OK;
1561 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1562 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1564 /* Make the extension value available for expansion */
1565 store_pool = POOL_PERM;
1566 tls_in.sni = string_copy(US servername);
1567 store_pool = old_pool;
1569 if (!reexpand_tls_files_for_sni)
1570 return SSL_TLSEXT_ERR_OK;
1572 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1573 not confident that memcpy wouldn't break some internal reference counting.
1574 Especially since there's a references struct member, which would be off. */
1576 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1577 if (!(server_sni = SSL_CTX_new(TLS_server_method())))
1579 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1582 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1583 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1587 /* Not sure how many of these are actually needed, since SSL object
1588 already exists. Might even need this selfsame callback, for reneg? */
1590 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1591 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1592 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1593 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1594 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1595 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1597 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1598 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1602 if ( cbinfo->server_cipher_list
1603 && !SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list))
1606 #ifndef DISABLE_OCSP
1607 if (cbinfo->u_ocsp.server.file)
1609 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1610 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1614 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1615 verify_callback_server, &dummy_errstr)) != OK)
1618 /* do this after setup_certs, because this can require the certs for verifying
1619 OCSP information. */
1620 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1623 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1624 SSL_set_SSL_CTX(s, server_sni);
1625 return SSL_TLSEXT_ERR_OK;
1627 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
1629 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1634 #ifndef DISABLE_OCSP
1636 /*************************************************
1637 * Callback to handle OCSP Stapling *
1638 *************************************************/
1640 /* Called when acting as server during the TLS session setup if the client
1641 requests OCSP information with a Certificate Status Request.
1643 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1649 tls_server_stapling_cb(SSL *s, void *arg)
1651 const tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1652 uschar *response_der; /*XXX blob */
1653 int response_der_len;
1655 /*XXX stack: use SSL_get_certificate() to see which cert; from that work
1656 out which ocsp blob to send. Unfortunately, SSL_get_certificate is known
1657 buggy in current OpenSSL; it returns the last cert loaded always rather than
1658 the one actually presented. So we can't support a stack of OCSP proofs at
1662 debug_printf("Received TLS status request (OCSP stapling); %s response\n",
1663 cbinfo->u_ocsp.server.response ? "have" : "lack");
1665 tls_in.ocsp = OCSP_NOT_RESP;
1666 if (!cbinfo->u_ocsp.server.response)
1667 return SSL_TLSEXT_ERR_NOACK;
1669 response_der = NULL;
1670 response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, /*XXX stack*/
1672 if (response_der_len <= 0)
1673 return SSL_TLSEXT_ERR_NOACK;
1675 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1676 tls_in.ocsp = OCSP_VFIED;
1677 return SSL_TLSEXT_ERR_OK;
1682 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1684 BIO_printf(bp, "\t%s: ", str);
1685 ASN1_GENERALIZEDTIME_print(bp, time);
1690 tls_client_stapling_cb(SSL *s, void *arg)
1692 tls_ext_ctx_cb * cbinfo = arg;
1693 const unsigned char * p;
1695 OCSP_RESPONSE * rsp;
1696 OCSP_BASICRESP * bs;
1699 DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
1700 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1703 /* Expect this when we requested ocsp but got none */
1704 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1705 log_write(0, LOG_MAIN, "Received TLS status callback, null content");
1707 DEBUG(D_tls) debug_printf(" null\n");
1708 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1711 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1713 tls_out.ocsp = OCSP_FAILED;
1714 if (LOGGING(tls_cipher))
1715 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1717 DEBUG(D_tls) debug_printf(" parse error\n");
1721 if(!(bs = OCSP_response_get1_basic(rsp)))
1723 tls_out.ocsp = OCSP_FAILED;
1724 if (LOGGING(tls_cipher))
1725 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1727 DEBUG(D_tls) debug_printf(" error parsing response\n");
1728 OCSP_RESPONSE_free(rsp);
1732 /* We'd check the nonce here if we'd put one in the request. */
1733 /* However that would defeat cacheability on the server so we don't. */
1735 /* This section of code reworked from OpenSSL apps source;
1736 The OpenSSL Project retains copyright:
1737 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1742 ASN1_GENERALIZEDTIME *rev, *thisupd, *nextupd;
1744 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1746 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1748 /* Use the chain that verified the server cert to verify the stapled info */
1749 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1751 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1752 cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
1754 tls_out.ocsp = OCSP_FAILED;
1755 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1756 "Received TLS cert status response, itself unverifiable: %s",
1757 ERR_reason_error_string(ERR_peek_error()));
1758 BIO_printf(bp, "OCSP response verify failure\n");
1759 ERR_print_errors(bp);
1760 OCSP_RESPONSE_print(bp, rsp, 0);
1764 BIO_printf(bp, "OCSP response well-formed and signed OK\n");
1766 /*XXX So we have a good stapled OCSP status. How do we know
1767 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1768 OCSP_resp_find_status() which matches on a cert id, which presumably
1769 we should use. Making an id needs OCSP_cert_id_new(), which takes
1770 issuerName, issuerKey, serialNumber. Are they all in the cert?
1772 For now, carry on blindly accepting the resp. */
1775 OCSP_SINGLERESP * single;
1777 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1778 if (OCSP_resp_count(bs) != 1)
1780 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1781 if (sk_OCSP_SINGLERESP_num(sresp) != 1)
1784 tls_out.ocsp = OCSP_FAILED;
1785 log_write(0, LOG_MAIN, "OCSP stapling "
1786 "with multiple responses not handled");
1789 single = OCSP_resp_get0(bs, 0);
1790 status = OCSP_single_get0_status(single, &reason, &rev,
1791 &thisupd, &nextupd);
1794 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1795 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1796 if (!OCSP_check_validity(thisupd, nextupd,
1797 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1799 tls_out.ocsp = OCSP_FAILED;
1800 DEBUG(D_tls) ERR_print_errors(bp);
1801 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1805 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1806 OCSP_cert_status_str(status));
1809 case V_OCSP_CERTSTATUS_GOOD:
1810 tls_out.ocsp = OCSP_VFIED;
1813 case V_OCSP_CERTSTATUS_REVOKED:
1814 tls_out.ocsp = OCSP_FAILED;
1815 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1816 reason != -1 ? "; reason: " : "",
1817 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1818 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1821 tls_out.ocsp = OCSP_FAILED;
1822 log_write(0, LOG_MAIN,
1823 "Server certificate status unknown, in OCSP stapling");
1828 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1833 OCSP_RESPONSE_free(rsp);
1836 #endif /*!DISABLE_OCSP*/
1839 /*************************************************
1840 * Initialize for TLS *
1841 *************************************************/
1843 /* Called from both server and client code, to do preliminary initialization
1844 of the library. We allocate and return a context structure.
1847 ctxp returned SSL context
1848 host connected host, if client; NULL if server
1849 dhparam DH parameter file
1850 certificate certificate file
1851 privatekey private key
1852 ocsp_file file of stapling info (server); flag for require ocsp (client)
1853 addr address if client; NULL if server (for some randomness)
1854 cbp place to put allocated callback context
1855 errstr error string pointer
1857 Returns: OK/DEFER/FAIL
1861 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
1863 #ifndef DISABLE_OCSP
1864 uschar *ocsp_file, /*XXX stack, in server*/
1866 address_item *addr, tls_ext_ctx_cb ** cbp,
1873 tls_ext_ctx_cb * cbinfo;
1875 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
1876 cbinfo->tlsp = tlsp;
1877 cbinfo->certificate = certificate;
1878 cbinfo->privatekey = privatekey;
1879 cbinfo->is_server = host==NULL;
1880 #ifndef DISABLE_OCSP
1881 cbinfo->verify_stack = NULL;
1884 cbinfo->u_ocsp.server.file = ocsp_file;
1885 cbinfo->u_ocsp.server.file_expanded = NULL;
1886 cbinfo->u_ocsp.server.response = NULL;
1889 cbinfo->u_ocsp.client.verify_store = NULL;
1891 cbinfo->dhparam = dhparam;
1892 cbinfo->server_cipher_list = NULL;
1893 cbinfo->host = host;
1894 #ifndef DISABLE_EVENT
1895 cbinfo->event_action = NULL;
1898 #ifdef EXIM_NEED_OPENSSL_INIT
1899 SSL_load_error_strings(); /* basic set up */
1900 OpenSSL_add_ssl_algorithms();
1903 #ifdef EXIM_HAVE_SHA256
1904 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
1905 list of available digests. */
1906 EVP_add_digest(EVP_sha256());
1909 /* Create a context.
1910 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
1911 negotiation in the different methods; as far as I can tell, the only
1912 *_{server,client}_method which allows negotiation is SSLv23, which exists even
1913 when OpenSSL is built without SSLv2 support.
1914 By disabling with openssl_options, we can let admins re-enable with the
1917 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1918 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
1920 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
1922 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
1924 /* It turns out that we need to seed the random number generator this early in
1925 order to get the full complement of ciphers to work. It took me roughly a day
1926 of work to discover this by experiment.
1928 On systems that have /dev/urandom, SSL may automatically seed itself from
1929 there. Otherwise, we have to make something up as best we can. Double check
1935 gettimeofday(&r.tv, NULL);
1938 RAND_seed(US (&r), sizeof(r));
1939 RAND_seed(US big_buffer, big_buffer_size);
1940 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
1943 return tls_error(US"RAND_status", host,
1944 US"unable to seed random number generator", errstr);
1947 /* Set up the information callback, which outputs if debugging is at a suitable
1952 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
1953 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
1954 /* this needs a debug build of OpenSSL */
1955 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
1957 #ifdef OPENSSL_HAVE_KEYLOG_CB
1958 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
1962 /* Automatically re-try reads/writes after renegotiation. */
1963 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
1965 /* Apply administrator-supplied work-arounds.
1966 Historically we applied just one requested option,
1967 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
1968 moved to an administrator-controlled list of options to specify and
1969 grandfathered in the first one as the default value for "openssl_options".
1971 No OpenSSL version number checks: the options we accept depend upon the
1972 availability of the option value macros from OpenSSL. */
1974 if (!tls_openssl_options_parse(openssl_options, &init_options))
1975 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
1977 #ifdef EXPERIMENTAL_TLS_RESUME
1978 tlsp->resumption = RESUME_SUPPORTED;
1982 #ifdef EXPERIMENTAL_TLS_RESUME
1983 /* Should the server offer session resumption? */
1984 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
1986 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
1987 init_options &= ~SSL_OP_NO_TICKET;
1988 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
1989 tlsp->host_resumable = TRUE;
1993 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
1994 if (!(SSL_CTX_set_options(ctx, init_options)))
1995 return tls_error(string_sprintf(
1996 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
1999 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2001 /* We'd like to disable session cache unconditionally, but foolish Outlook
2002 Express clients then give up the first TLS connection and make a second one
2003 (which works). Only when there is an IMAP service on the same machine.
2004 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2005 now, until we work out a decent way of presenting control to the config. It
2006 will never be used because we use a new context every time. */
2008 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2011 /* Initialize with DH parameters if supplied */
2012 /* Initialize ECDH temp key parameter selection */
2014 if ( !init_dh(ctx, dhparam, host, errstr)
2015 || !init_ecdh(ctx, host, errstr)
2019 /* Set up certificate and key (and perhaps OCSP info) */
2021 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
2024 /* If we need to handle SNI or OCSP, do so */
2026 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2027 # ifndef DISABLE_OCSP
2028 if (!(cbinfo->verify_stack = sk_X509_new_null()))
2030 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2035 if (!host) /* server */
2037 # ifndef DISABLE_OCSP
2038 /* We check u_ocsp.server.file, not server.response, because we care about if
2039 the option exists, not what the current expansion might be, as SNI might
2040 change the certificate and OCSP file in use between now and the time the
2041 callback is invoked. */
2042 if (cbinfo->u_ocsp.server.file)
2044 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2045 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2048 /* We always do this, so that $tls_sni is available even if not used in
2050 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2051 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
2053 # ifndef DISABLE_OCSP
2055 if(ocsp_file) /* wanting stapling */
2057 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
2059 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2062 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2063 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2068 cbinfo->verify_cert_hostnames = NULL;
2070 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2071 /* Set up the RSA callback */
2072 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2075 /* Finally, set the session cache timeout, and we are done.
2076 The period appears to be also used for (server-generated) session tickets */
2078 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2079 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2090 /*************************************************
2091 * Get name of cipher in use *
2092 *************************************************/
2095 Argument: pointer to an SSL structure for the connection
2096 pointer to number of bits for cipher
2097 Returns: pointer to allocated string in perm-pool
2101 construct_cipher_name(SSL * ssl, int * bits)
2103 int pool = store_pool;
2104 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2105 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2106 the accessor functions use const in the prototype. */
2108 const uschar * ver = CUS SSL_get_version(ssl);
2109 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2112 SSL_CIPHER_get_bits(c, bits);
2114 store_pool = POOL_PERM;
2115 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2117 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2122 /* Get IETF-standard name for ciphersuite.
2123 Argument: pointer to an SSL structure for the connection
2124 Returns: pointer to string
2127 static const uschar *
2128 cipher_stdname_ssl(SSL * ssl)
2130 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2131 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2133 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2134 return cipher_stdname(id >> 8, id & 0xff);
2140 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2142 /*XXX we might consider a list-of-certs variable for the cert chain.
2143 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2144 in list-handling functions, also consider the difference between the entire
2145 chain and the elements sent by the peer. */
2147 tlsp->peerdn = NULL;
2149 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2150 if (!tlsp->peercert)
2151 tlsp->peercert = SSL_get_peer_certificate(ssl);
2152 /* Beware anonymous ciphers which lead to server_cert being NULL */
2154 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2155 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2158 int oldpool = store_pool;
2160 peerdn[siz-1] = '\0'; /* paranoia */
2161 store_pool = POOL_PERM;
2162 tlsp->peerdn = string_copy(peerdn);
2163 store_pool = oldpool;
2165 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2166 but they don't get called on session-resumption. So use the official
2167 interface, which uses the resumed value. Unfortunately this claims verified
2168 when it actually failed but we're in try-verify mode, due to us wanting the
2169 knowlege that it failed so needing to have the callback and forcing a
2170 permissive return. If we don't force it, the TLS startup is failed.
2171 Hence the verify_override bodge - though still a problem for resumption. */
2173 if (!tlsp->verify_override)
2174 tlsp->certificate_verified = SSL_get_verify_result(ssl) == X509_V_OK;
2182 /*************************************************
2183 * Set up for verifying certificates *
2184 *************************************************/
2186 #ifndef DISABLE_OCSP
2187 /* Load certs from file, return TRUE on success */
2190 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
2195 while (sk_X509_num(verify_stack) > 0)
2196 X509_free(sk_X509_pop(verify_stack));
2198 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2199 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
2200 sk_X509_push(verify_stack, x);
2208 /* Called by both client and server startup; on the server possibly
2209 repeated after a Server Name Indication.
2212 sctx SSL_CTX* to initialise
2213 certs certs file or NULL
2214 crl CRL file or NULL
2215 host NULL in a server; the remote host in a client
2216 optional TRUE if called from a server for a host in tls_try_verify_hosts;
2217 otherwise passed as FALSE
2218 cert_vfy_cb Callback function for certificate verification
2219 errstr error string pointer
2221 Returns: OK/DEFER/FAIL
2225 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
2226 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
2228 uschar *expcerts, *expcrl;
2230 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2232 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2234 if (expcerts && *expcerts)
2236 /* Tell the library to use its compiled-in location for the system default
2237 CA bundle. Then add the ones specified in the config, if any. */
2239 if (!SSL_CTX_set_default_verify_paths(sctx))
2240 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2242 if (Ustrcmp(expcerts, "system") != 0)
2244 struct stat statbuf;
2246 if (Ustat(expcerts, &statbuf) < 0)
2248 log_write(0, LOG_MAIN|LOG_PANIC,
2249 "failed to stat %s for certificates", expcerts);
2255 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2256 { file = NULL; dir = expcerts; }
2259 file = expcerts; dir = NULL;
2260 #ifndef DISABLE_OCSP
2261 /* In the server if we will be offering an OCSP proof, load chain from
2262 file for verifying the OCSP proof at load time. */
2265 && statbuf.st_size > 0
2266 && server_static_cbinfo->u_ocsp.server.file
2267 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
2270 log_write(0, LOG_MAIN|LOG_PANIC,
2271 "failed to load cert chain from %s", file);
2277 /* If a certificate file is empty, the next function fails with an
2278 unhelpful error message. If we skip it, we get the correct behaviour (no
2279 certificates are recognized, but the error message is still misleading (it
2280 says no certificate was supplied). But this is better. */
2282 if ( (!file || statbuf.st_size > 0)
2283 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2284 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
2286 /* Load the list of CAs for which we will accept certs, for sending
2287 to the client. This is only for the one-file tls_verify_certificates
2289 If a list isn't loaded into the server, but some verify locations are set,
2290 the server end appears to make a wildcard request for client certs.
2291 Meanwhile, the client library as default behaviour *ignores* the list
2292 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2293 Because of this, and that the dir variant is likely only used for
2294 the public-CA bundle (not for a private CA), not worth fixing. */
2298 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2300 SSL_CTX_set_client_CA_list(sctx, names);
2301 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
2302 sk_X509_NAME_num(names));
2307 /* Handle a certificate revocation list. */
2309 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2311 /* This bit of code is now the version supplied by Lars Mainka. (I have
2312 merely reformatted it into the Exim code style.)
2314 "From here I changed the code to add support for multiple crl's
2315 in pem format in one file or to support hashed directory entries in
2316 pem format instead of a file. This method now uses the library function
2317 X509_STORE_load_locations to add the CRL location to the SSL context.
2318 OpenSSL will then handle the verify against CA certs and CRLs by
2319 itself in the verify callback." */
2321 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
2322 if (expcrl && *expcrl)
2324 struct stat statbufcrl;
2325 if (Ustat(expcrl, &statbufcrl) < 0)
2327 log_write(0, LOG_MAIN|LOG_PANIC,
2328 "failed to stat %s for certificates revocation lists", expcrl);
2333 /* is it a file or directory? */
2335 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
2336 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
2340 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
2346 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
2348 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
2349 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
2351 /* setting the flags to check against the complete crl chain */
2353 X509_STORE_set_flags(cvstore,
2354 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
2358 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2360 /* If verification is optional, don't fail if no certificate */
2362 SSL_CTX_set_verify(sctx,
2363 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2372 /*************************************************
2373 * Start a TLS session in a server *
2374 *************************************************/
2376 /* This is called when Exim is running as a server, after having received
2377 the STARTTLS command. It must respond to that command, and then negotiate
2381 require_ciphers allowed ciphers
2382 errstr pointer to error message
2384 Returns: OK on success
2385 DEFER for errors before the start of the negotiation
2386 FAIL for errors during the negotiation; the server can't
2391 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2394 uschar * expciphers;
2395 tls_ext_ctx_cb * cbinfo;
2396 static uschar peerdn[256];
2398 /* Check for previous activation */
2400 if (tls_in.active.sock >= 0)
2402 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
2403 smtp_printf("554 Already in TLS\r\n", FALSE);
2407 /* Initialize the SSL library. If it fails, it will already have logged
2410 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
2411 #ifndef DISABLE_OCSP
2412 tls_ocsp_file, /*XXX stack*/
2414 NULL, &server_static_cbinfo, &tls_in, errstr);
2415 if (rc != OK) return rc;
2416 cbinfo = server_static_cbinfo;
2418 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2421 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2422 were historically separated by underscores. So that I can use either form in my
2423 tests, and also for general convenience, we turn underscores into hyphens here.
2425 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2426 for TLS 1.3 . Since we do not call it at present we get the default list:
2427 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2432 for (uschar * s = expciphers; *s; s++ ) if (*s == '_') *s = '-';
2433 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2434 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2435 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2436 cbinfo->server_cipher_list = expciphers;
2439 /* If this is a host for which certificate verification is mandatory or
2440 optional, set up appropriately. */
2442 tls_in.certificate_verified = FALSE;
2444 tls_in.dane_verified = FALSE;
2446 server_verify_callback_called = FALSE;
2448 if (verify_check_host(&tls_verify_hosts) == OK)
2450 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2451 FALSE, verify_callback_server, errstr);
2452 if (rc != OK) return rc;
2453 server_verify_optional = FALSE;
2455 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2457 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2458 TRUE, verify_callback_server, errstr);
2459 if (rc != OK) return rc;
2460 server_verify_optional = TRUE;
2463 #ifdef EXPERIMENTAL_TLS_RESUME
2464 SSL_CTX_set_tlsext_ticket_key_cb(server_ctx, ticket_key_callback);
2465 /* despite working, appears to always return failure, so ignoring */
2467 #ifdef OPENSSL_HAVE_NUM_TICKETS
2468 # ifdef EXPERIMENTAL_TLS_RESUME
2469 SSL_CTX_set_num_tickets(server_ctx, tls_in.host_resumable ? 1 : 0);
2471 SSL_CTX_set_num_tickets(server_ctx, 0); /* send no TLS1.3 stateful-tickets */
2476 /* Prepare for new connection */
2478 if (!(server_ssl = SSL_new(server_ctx)))
2479 return tls_error(US"SSL_new", NULL, NULL, errstr);
2481 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2483 * With the SSL_clear(), we get strange interoperability bugs with
2484 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2485 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2487 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2488 * session shutdown. In this case, we have a brand new object and there's no
2489 * obvious reason to immediately clear it. I'm guessing that this was
2490 * originally added because of incomplete initialisation which the clear fixed,
2491 * in some historic release.
2494 /* Set context and tell client to go ahead, except in the case of TLS startup
2495 on connection, where outputting anything now upsets the clients and tends to
2496 make them disconnect. We need to have an explicit fflush() here, to force out
2497 the response. Other smtp_printf() calls do not need it, because in non-TLS
2498 mode, the fflush() happens when smtp_getc() is called. */
2500 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2501 if (!tls_in.on_connect)
2503 smtp_printf("220 TLS go ahead\r\n", FALSE);
2507 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2508 that the OpenSSL library doesn't. */
2510 SSL_set_wfd(server_ssl, fileno(smtp_out));
2511 SSL_set_rfd(server_ssl, fileno(smtp_in));
2512 SSL_set_accept_state(server_ssl);
2514 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2516 sigalrm_seen = FALSE;
2517 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2518 rc = SSL_accept(server_ssl);
2523 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2527 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2528 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
2529 anon-authentication ciphersuite negotiated. */
2531 #ifdef EXPERIMENTAL_TLS_RESUME
2532 if (SSL_session_reused(server_ssl))
2534 tls_in.resumption |= RESUME_USED;
2535 DEBUG(D_tls) debug_printf("Session reused\n");
2539 /* TLS has been set up. Adjust the input functions to read via TLS,
2540 and initialize things. */
2542 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2544 tls_in.cipher = construct_cipher_name(server_ssl, &tls_in.bits);
2545 tls_in.cipher_stdname = cipher_stdname_ssl(server_ssl);
2550 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)))
2551 debug_printf("Shared ciphers: %s\n", buf);
2553 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
2555 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2556 SSL_SESSION_print_keylog(bp, SSL_get_session(server_ssl));
2561 #ifdef EXIM_HAVE_SESSION_TICKET
2563 SSL_SESSION * ss = SSL_get_session(server_ssl);
2564 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
2565 debug_printf("The session has a ticket, life %lu seconds\n",
2566 SSL_SESSION_get_ticket_lifetime_hint(ss));
2571 /* Record the certificate we presented */
2573 X509 * crt = SSL_get_certificate(server_ssl);
2574 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2577 /* Only used by the server-side tls (tls_in), including tls_getc.
2578 Client-side (tls_out) reads (seem to?) go via
2579 smtp_read_response()/ip_recv().
2580 Hence no need to duplicate for _in and _out.
2582 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2583 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2584 ssl_xfer_eof = ssl_xfer_error = FALSE;
2586 receive_getc = tls_getc;
2587 receive_getbuf = tls_getbuf;
2588 receive_get_cache = tls_get_cache;
2589 receive_ungetc = tls_ungetc;
2590 receive_feof = tls_feof;
2591 receive_ferror = tls_ferror;
2592 receive_smtp_buffered = tls_smtp_buffered;
2594 tls_in.active.sock = fileno(smtp_out);
2595 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
2603 tls_client_basic_ctx_init(SSL_CTX * ctx,
2604 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2608 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2609 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2610 the specified host patterns if one of them is defined */
2612 if ( ( !ob->tls_verify_hosts
2613 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2615 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2617 client_verify_optional = FALSE;
2618 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2619 client_verify_optional = TRUE;
2623 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2624 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2628 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2630 cbinfo->verify_cert_hostnames =
2632 string_domain_utf8_to_alabel(host->name, NULL);
2636 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2637 cbinfo->verify_cert_hostnames);
2645 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2648 const char * hostnames[2] = { CS host->name, NULL };
2651 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2652 return tls_error(US"hostnames load", host, NULL, errstr);
2654 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2655 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2656 ) if (rr->type == T_TLSA && rr->size > 3)
2658 const uschar * p = rr->data;
2659 uint8_t usage, selector, mtype;
2660 const char * mdname;
2664 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2665 if (usage != 2 && usage != 3) continue;
2672 default: continue; /* Only match-types 0, 1, 2 are supported */
2673 case 0: mdname = NULL; break;
2674 case 1: mdname = "sha256"; break;
2675 case 2: mdname = "sha512"; break;
2679 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2682 return tls_error(US"tlsa load", host, NULL, errstr);
2683 case 0: /* action not taken */
2687 tls_out.tlsa_usage |= 1<<usage;
2693 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2696 #endif /*SUPPORT_DANE*/
2700 #ifdef EXPERIMENTAL_TLS_RESUME
2701 /* On the client, get any stashed session for the given IP from hints db
2702 and apply it to the ssl-connection for attempted resumption. */
2705 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
2707 tlsp->resumption |= RESUME_SUPPORTED;
2708 if (tlsp->host_resumable)
2710 dbdata_tls_session * dt;
2712 open_db dbblock, * dbm_file;
2714 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2715 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
2716 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
2718 /* key for the db is the IP */
2719 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
2721 SSL_SESSION * ss = NULL;
2722 const uschar * sess_asn1 = dt->session;
2724 len -= sizeof(dbdata_tls_session);
2725 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
2729 ERR_error_string_n(ERR_get_error(),
2730 ssl_errstring, sizeof(ssl_errstring));
2731 debug_printf("decoding session: %s\n", ssl_errstring);
2734 else if (!SSL_set_session(ssl, ss))
2738 ERR_error_string_n(ERR_get_error(),
2739 ssl_errstring, sizeof(ssl_errstring));
2740 debug_printf("applying session to ssl: %s\n", ssl_errstring);
2745 DEBUG(D_tls) debug_printf("good session\n");
2746 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2750 DEBUG(D_tls) debug_printf("no session record\n");
2751 dbfn_close(dbm_file);
2757 /* On the client, save the session for later resumption */
2760 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
2762 tls_ext_ctx_cb * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
2765 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
2767 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
2769 # ifdef OPENSSL_HAVE_NUM_TICKETS
2770 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
2773 int len = i2d_SSL_SESSION(ss, NULL);
2774 int dlen = sizeof(dbdata_tls_session) + len;
2775 dbdata_tls_session * dt = store_get(dlen);
2776 uschar * s = dt->session;
2777 open_db dbblock, * dbm_file;
2779 DEBUG(D_tls) debug_printf("session is resumable\n");
2780 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
2782 len = i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
2784 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
2786 const uschar * key = cbinfo->host->address;
2787 dbfn_delete(dbm_file, key);
2788 dbfn_write(dbm_file, key, dt, dlen);
2789 dbfn_close(dbm_file);
2790 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
2799 tls_client_ctx_resume_prehandshake(
2800 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
2801 smtp_transport_options_block * ob, host_item * host)
2803 /* Should the client request a session resumption ticket? */
2804 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
2806 tlsp->host_resumable = TRUE;
2808 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
2809 SSL_SESS_CACHE_CLIENT
2810 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
2811 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
2816 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
2817 host_item * host, uschar ** errstr)
2819 if (tlsp->host_resumable)
2822 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
2823 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
2825 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
2826 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_cbinfo))
2828 tls_error(US"set ex_data", host, NULL, errstr);
2831 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_cbinfo);
2834 tlsp->resumption = RESUME_SUPPORTED;
2835 /* Pick up a previous session, saved on an old ticket */
2836 tls_retrieve_session(tlsp, ssl, host->address);
2841 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
2844 if (SSL_session_reused(exim_client_ctx->ssl))
2846 DEBUG(D_tls) debug_printf("The session was reused\n");
2847 tlsp->resumption |= RESUME_USED;
2850 #endif /* EXPERIMENTAL_TLS_RESUME */
2853 /*************************************************
2854 * Start a TLS session in a client *
2855 *************************************************/
2857 /* Called from the smtp transport after STARTTLS has been accepted.
2860 cctx connection context
2861 conn_args connection details
2862 cookie datum for randomness; can be NULL
2863 tlsp record details of TLS channel configuration here; must be non-NULL
2864 errstr error string pointer
2866 Returns: TRUE for success with TLS session context set in connection context,
2871 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
2872 void * cookie, tls_support * tlsp, uschar ** errstr)
2874 host_item * host = conn_args->host; /* for msgs and option-tests */
2875 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
2876 smtp_transport_options_block * ob = tb
2877 ? (smtp_transport_options_block *)tb->options_block
2878 : &smtp_transport_option_defaults;
2879 exim_openssl_client_tls_ctx * exim_client_ctx;
2880 uschar * expciphers;
2882 static uschar peerdn[256];
2884 #ifndef DISABLE_OCSP
2885 BOOL request_ocsp = FALSE;
2886 BOOL require_ocsp = FALSE;
2890 store_pool = POOL_PERM;
2891 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx));
2892 exim_client_ctx->corked = NULL;
2896 tlsp->tlsa_usage = 0;
2899 #ifndef DISABLE_OCSP
2901 # ifdef SUPPORT_DANE
2902 if ( conn_args->dane
2903 && ob->hosts_request_ocsp[0] == '*'
2904 && ob->hosts_request_ocsp[1] == '\0'
2907 /* Unchanged from default. Use a safer one under DANE */
2908 request_ocsp = TRUE;
2909 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
2910 " {= {4}{$tls_out_tlsa_usage}} } "
2916 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
2917 request_ocsp = TRUE;
2919 # ifdef SUPPORT_DANE
2923 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
2927 rc = tls_init(&exim_client_ctx->ctx, host, NULL,
2928 ob->tls_certificate, ob->tls_privatekey,
2929 #ifndef DISABLE_OCSP
2930 (void *)(long)request_ocsp,
2932 cookie, &client_static_cbinfo, tlsp, errstr);
2933 if (rc != OK) return FALSE;
2935 tlsp->certificate_verified = FALSE;
2936 client_verify_callback_called = FALSE;
2940 if (conn_args->dane)
2942 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
2943 other failures should be treated as problems. */
2944 if (ob->dane_require_tls_ciphers &&
2945 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
2946 &expciphers, errstr))
2948 if (expciphers && *expciphers == '\0')
2953 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
2954 &expciphers, errstr))
2957 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2958 are separated by underscores. So that I can use either form in my tests, and
2959 also for general convenience, we turn underscores into hyphens here. */
2963 uschar *s = expciphers;
2964 while (*s) { if (*s == '_') *s = '-'; s++; }
2965 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2966 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
2968 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
2974 if (conn_args->dane)
2976 SSL_CTX_set_verify(exim_client_ctx->ctx,
2977 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
2978 verify_callback_client_dane);
2980 if (!DANESSL_library_init())
2982 tls_error(US"library init", host, NULL, errstr);
2985 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
2987 tls_error(US"context init", host, NULL, errstr);
2995 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
2996 client_static_cbinfo, errstr) != OK)
2999 #ifdef EXPERIMENTAL_TLS_RESUME
3000 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3004 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3006 tls_error(US"SSL_new", host, NULL, errstr);
3009 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3011 #ifdef EXPERIMENTAL_TLS_RESUME
3012 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3017 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3018 SSL_set_connect_state(exim_client_ctx->ssl);
3022 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3026 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3028 else if (!Ustrlen(tlsp->sni))
3032 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3033 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3034 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3036 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3043 if (conn_args->dane)
3044 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3048 #ifndef DISABLE_OCSP
3049 /* Request certificate status at connection-time. If the server
3050 does OCSP stapling we will get the callback (set in tls_init()) */
3051 # ifdef SUPPORT_DANE
3055 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3056 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3058 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3059 this means we avoid the OCSP request, we wasted the setup
3060 cost in tls_init(). */
3061 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3062 request_ocsp = require_ocsp
3063 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3070 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3071 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
3072 tlsp->ocsp = OCSP_NOT_RESP;
3076 #ifndef DISABLE_EVENT
3077 client_static_cbinfo->event_action = tb ? tb->event_action : NULL;
3080 /* There doesn't seem to be a built-in timeout on connection. */
3082 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3083 sigalrm_seen = FALSE;
3084 ALARM(ob->command_timeout);
3085 rc = SSL_connect(exim_client_ctx->ssl);
3089 if (conn_args->dane)
3090 DANESSL_cleanup(exim_client_ctx->ssl);
3095 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
3101 debug_printf("SSL_connect succeeded\n");
3102 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3104 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3105 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
3111 #ifdef EXPERIMENTAL_TLS_RESUME
3112 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
3115 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
3117 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, &tlsp->bits);
3118 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
3120 /* Record the certificate we presented */
3122 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
3123 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
3126 tlsp->active.sock = cctx->sock;
3127 tlsp->active.tls_ctx = exim_client_ctx;
3128 cctx->tls_ctx = exim_client_ctx;
3137 tls_refill(unsigned lim)
3142 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
3143 ssl_xfer_buffer, ssl_xfer_buffer_size);
3145 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3146 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
3147 MIN(ssl_xfer_buffer_size, lim));
3148 error = SSL_get_error(server_ssl, inbytes);
3149 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3151 if (had_command_timeout) /* set by signal handler */
3152 smtp_command_timeout_exit(); /* does not return */
3153 if (had_command_sigterm)
3154 smtp_command_sigterm_exit();
3155 if (had_data_timeout)
3156 smtp_data_timeout_exit();
3157 if (had_data_sigint)
3158 smtp_data_sigint_exit();
3160 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3161 closed down, not that the socket itself has been closed down. Revert to
3162 non-SSL handling. */
3166 case SSL_ERROR_NONE:
3169 case SSL_ERROR_ZERO_RETURN:
3170 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3172 receive_getc = smtp_getc;
3173 receive_getbuf = smtp_getbuf;
3174 receive_get_cache = smtp_get_cache;
3175 receive_ungetc = smtp_ungetc;
3176 receive_feof = smtp_feof;
3177 receive_ferror = smtp_ferror;
3178 receive_smtp_buffered = smtp_buffered;
3180 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
3181 SSL_shutdown(server_ssl);
3183 #ifndef DISABLE_OCSP
3184 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
3185 server_static_cbinfo->verify_stack = NULL;
3187 SSL_free(server_ssl);
3188 SSL_CTX_free(server_ctx);
3191 tls_in.active.sock = -1;
3192 tls_in.active.tls_ctx = NULL;
3194 tls_in.cipher = NULL;
3195 tls_in.peerdn = NULL;
3200 /* Handle genuine errors */
3202 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3203 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
3204 ssl_xfer_error = TRUE;
3208 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3209 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
3210 debug_printf(" - syscall %s\n", strerror(errno));
3211 ssl_xfer_error = TRUE;
3215 #ifndef DISABLE_DKIM
3216 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
3218 ssl_xfer_buffer_hwm = inbytes;
3219 ssl_xfer_buffer_lwm = 0;
3224 /*************************************************
3225 * TLS version of getc *
3226 *************************************************/
3228 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3229 it refills the buffer via the SSL reading function.
3231 Arguments: lim Maximum amount to read/buffer
3232 Returns: the next character or EOF
3234 Only used by the server-side TLS.
3238 tls_getc(unsigned lim)
3240 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3241 if (!tls_refill(lim))
3242 return ssl_xfer_error ? EOF : smtp_getc(lim);
3244 /* Something in the buffer; return next uschar */
3246 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
3250 tls_getbuf(unsigned * len)
3255 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3256 if (!tls_refill(*len))
3258 if (!ssl_xfer_error) return smtp_getbuf(len);
3263 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
3265 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
3266 ssl_xfer_buffer_lwm += size;
3275 #ifndef DISABLE_DKIM
3276 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
3278 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
3284 tls_could_read(void)
3286 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
3290 /*************************************************
3291 * Read bytes from TLS channel *
3292 *************************************************/
3296 ct_ctx client context pointer, or NULL for the one global server context
3300 Returns: the number of bytes read
3301 -1 after a failed read, including EOF
3303 Only used by the client-side TLS.
3307 tls_read(void * ct_ctx, uschar *buff, size_t len)
3309 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3313 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3314 buff, (unsigned int)len);
3316 inbytes = SSL_read(ssl, CS buff, len);
3317 error = SSL_get_error(ssl, inbytes);
3319 if (error == SSL_ERROR_ZERO_RETURN)
3321 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3324 else if (error != SSL_ERROR_NONE)
3334 /*************************************************
3335 * Write bytes down TLS channel *
3336 *************************************************/
3340 ct_ctx client context pointer, or NULL for the one global server context
3343 more further data expected soon
3345 Returns: the number of bytes after a successful write,
3346 -1 after a failed write
3348 Used by both server-side and client-side TLS.
3352 tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more)
3355 int outbytes, error;
3357 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3358 static gstring * server_corked = NULL;
3359 gstring ** corkedp = ct_ctx
3360 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
3361 gstring * corked = *corkedp;
3363 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
3364 buff, (unsigned long)len, more ? ", more" : "");
3366 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
3367 "more" is notified. This hack is only ok if small amounts are involved AND only
3368 one stream does it, in one context (i.e. no store reset). Currently it is used
3369 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
3370 We support callouts done by the server process by using a separate client
3371 context for the stashed information. */
3372 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
3373 a store reset there, so use POOL_PERM. */
3374 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
3376 if ((more || corked))
3378 #ifdef EXPERIMENTAL_PIPE_CONNECT
3379 int save_pool = store_pool;
3380 store_pool = POOL_PERM;
3383 corked = string_catn(corked, buff, len);
3385 #ifdef EXPERIMENTAL_PIPE_CONNECT
3386 store_pool = save_pool;
3394 buff = CUS corked->s;
3399 for (int left = len; left > 0;)
3401 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
3402 outbytes = SSL_write(ssl, CS buff, left);
3403 error = SSL_get_error(ssl, outbytes);
3404 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
3408 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3409 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
3412 case SSL_ERROR_NONE:
3417 case SSL_ERROR_ZERO_RETURN:
3418 log_write(0, LOG_MAIN, "SSL channel closed on write");
3421 case SSL_ERROR_SYSCALL:
3422 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
3423 sender_fullhost ? sender_fullhost : US"<unknown>",
3428 log_write(0, LOG_MAIN, "SSL_write error %d", error);
3437 /*************************************************
3438 * Close down a TLS session *
3439 *************************************************/
3441 /* This is also called from within a delivery subprocess forked from the
3442 daemon, to shut down the TLS library, without actually doing a shutdown (which
3443 would tamper with the SSL session in the parent process).
3446 ct_ctx client TLS context pointer, or NULL for the one global server context
3447 shutdown 1 if TLS close-alert is to be sent,
3448 2 if also response to be waited for
3452 Used by both server-side and client-side TLS.
3456 tls_close(void * ct_ctx, int shutdown)
3458 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
3459 SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx;
3460 SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl;
3461 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
3463 if (*fdp < 0) return; /* TLS was not active */
3468 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3469 shutdown > 1 ? " (with response-wait)" : "");
3471 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
3475 rc = SSL_shutdown(*sslp); /* wait for response */
3479 if (rc < 0) DEBUG(D_tls)
3481 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3482 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
3486 #ifndef DISABLE_OCSP
3487 if (!o_ctx) /* server side */
3489 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
3490 server_static_cbinfo->verify_stack = NULL;
3494 SSL_CTX_free(*ctxp);
3504 /*************************************************
3505 * Let tls_require_ciphers be checked at startup *
3506 *************************************************/
3508 /* The tls_require_ciphers option, if set, must be something which the
3511 Returns: NULL on success, or error message
3515 tls_validate_require_cipher(void)
3518 uschar *s, *expciphers, *err;
3520 /* this duplicates from tls_init(), we need a better "init just global
3521 state, for no specific purpose" singleton function of our own */
3523 #ifdef EXIM_NEED_OPENSSL_INIT
3524 SSL_load_error_strings();
3525 OpenSSL_add_ssl_algorithms();
3527 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
3528 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
3529 list of available digests. */
3530 EVP_add_digest(EVP_sha256());
3533 if (!(tls_require_ciphers && *tls_require_ciphers))
3536 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3538 return US"failed to expand tls_require_ciphers";
3540 if (!(expciphers && *expciphers))
3543 /* normalisation ripped from above */
3545 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
3549 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3550 if (!(ctx = SSL_CTX_new(TLS_server_method())))
3552 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
3555 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3556 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
3560 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3562 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
3564 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3565 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3566 expciphers, ssl_errstring);
3577 /*************************************************
3578 * Report the library versions. *
3579 *************************************************/
3581 /* There have historically been some issues with binary compatibility in
3582 OpenSSL libraries; if Exim (like many other applications) is built against
3583 one version of OpenSSL but the run-time linker picks up another version,
3584 it can result in serious failures, including crashing with a SIGSEGV. So
3585 report the version found by the compiler and the run-time version.
3587 Note: some OS vendors backport security fixes without changing the version
3588 number/string, and the version date remains unchanged. The _build_ date
3589 will change, so we can more usefully assist with version diagnosis by also
3590 reporting the build date.
3592 Arguments: a FILE* to print the results to
3597 tls_version_report(FILE *f)
3599 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
3602 OPENSSL_VERSION_TEXT,
3603 SSLeay_version(SSLEAY_VERSION),
3604 SSLeay_version(SSLEAY_BUILT_ON));
3605 /* third line is 38 characters for the %s and the line is 73 chars long;
3606 the OpenSSL output includes a "built on: " prefix already. */
3612 /*************************************************
3613 * Random number generation *
3614 *************************************************/
3616 /* Pseudo-random number generation. The result is not expected to be
3617 cryptographically strong but not so weak that someone will shoot themselves
3618 in the foot using it as a nonce in input in some email header scheme or
3619 whatever weirdness they'll twist this into. The result should handle fork()
3620 and avoid repeating sequences. OpenSSL handles that for us.
3624 Returns a random number in range [0, max-1]
3628 vaguely_random_number(int max)
3632 static pid_t pidlast = 0;
3634 uschar smallbuf[sizeof(r)];
3640 if (pidnow != pidlast)
3642 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3643 is unique for each thread", this doesn't apparently apply across processes,
3644 so our own warning from vaguely_random_number_fallback() applies here too.
3645 Fix per PostgreSQL. */
3651 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3655 gettimeofday(&r.tv, NULL);
3658 RAND_seed(US (&r), sizeof(r));
3660 /* We're after pseudo-random, not random; if we still don't have enough data
3661 in the internal PRNG then our options are limited. We could sleep and hope
3662 for entropy to come along (prayer technique) but if the system is so depleted
3663 in the first place then something is likely to just keep taking it. Instead,
3664 we'll just take whatever little bit of pseudo-random we can still manage to
3667 needed_len = sizeof(r);
3668 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3669 asked for a number less than 10. */
3670 for (r = max, i = 0; r; ++i)
3676 #ifdef EXIM_HAVE_RAND_PSEUDO
3677 /* We do not care if crypto-strong */
3678 i = RAND_pseudo_bytes(smallbuf, needed_len);
3680 i = RAND_bytes(smallbuf, needed_len);
3686 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3687 return vaguely_random_number_fallback(max);
3691 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3694 /* We don't particularly care about weighted results; if someone wants
3695 smooth distribution and cares enough then they should submit a patch then. */
3702 /*************************************************
3703 * OpenSSL option parse *
3704 *************************************************/
3706 /* Parse one option for tls_openssl_options_parse below
3709 name one option name
3710 value place to store a value for it
3711 Returns success or failure in parsing
3717 tls_openssl_one_option_parse(uschar *name, long *value)
3720 int last = exim_openssl_options_size;
3721 while (last > first)
3723 int middle = (first + last)/2;
3724 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3727 *value = exim_openssl_options[middle].value;
3741 /*************************************************
3742 * OpenSSL option parsing logic *
3743 *************************************************/
3745 /* OpenSSL has a number of compatibility options which an administrator might
3746 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3747 we look like log_selector.
3750 option_spec the administrator-supplied string of options
3751 results ptr to long storage for the options bitmap
3752 Returns success or failure
3756 tls_openssl_options_parse(uschar *option_spec, long *results)
3761 BOOL adding, item_parsed;
3763 /* Server: send no (<= TLS1.2) session tickets */
3764 result = SSL_OP_NO_TICKET;
3766 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3767 * from default because it increases BEAST susceptibility. */
3768 #ifdef SSL_OP_NO_SSLv2
3769 result |= SSL_OP_NO_SSLv2;
3771 #ifdef SSL_OP_NO_SSLv3
3772 result |= SSL_OP_NO_SSLv3;
3774 #ifdef SSL_OP_SINGLE_DH_USE
3775 result |= SSL_OP_SINGLE_DH_USE;
3784 for (uschar * s = option_spec; *s; /**/)
3786 while (isspace(*s)) ++s;
3789 if (*s != '+' && *s != '-')
3791 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
3792 "+ or - expected but found \"%s\"\n", s);
3795 adding = *s++ == '+';
3796 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
3799 item_parsed = tls_openssl_one_option_parse(s, &item);
3803 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
3806 DEBUG(D_tls) debug_printf("openssl option, %s %8lx: %lx (%s)\n",
3807 adding ? "adding to " : "removing from", result, item, s);
3819 #endif /*!MACRO_PREDEF*/
3822 /* End of tls-openssl.c */