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
49 # define OPENSSL_AUTO_SHA256
51 # define EXIM_HAVE_EPHEM_RSA_KEX
52 # define EXIM_HAVE_RAND_PSEUDO
54 #if (OPENSSL_VERSION_NUMBER >= 0x0090800fL) && !defined(OPENSSL_NO_SHA256)
55 # define EXIM_HAVE_SHA256
58 /* X509_check_host provides sane certificate hostname checking, but was added
59 to OpenSSL late, after other projects forked off the code-base. So in
60 addition to guarding against the base version number, beware that LibreSSL
61 does not (at this time) support this function.
63 If LibreSSL gains a different API, perhaps via libtls, then we'll probably
64 opt to disentangle and ask a LibreSSL user to provide glue for a third
65 crypto provider for libtls instead of continuing to tie the OpenSSL glue
66 into even twistier knots. If LibreSSL gains the same API, we can just
67 change this guard and punt the issue for a while longer. */
69 #ifndef LIBRESSL_VERSION_NUMBER
70 # if OPENSSL_VERSION_NUMBER >= 0x010100000L
71 # define EXIM_HAVE_OPENSSL_CHECKHOST
72 # define EXIM_HAVE_OPENSSL_DH_BITS
73 # define EXIM_HAVE_OPENSSL_TLS_METHOD
74 # define EXIM_HAVE_OPENSSL_KEYLOG
75 # define EXIM_HAVE_OPENSSL_CIPHER_GET_ID
76 # define EXIM_HAVE_SESSION_TICKET
77 # define EXIM_HAVE_OPESSL_TRACE
78 # define EXIM_HAVE_OPESSL_GET0_SERIAL
80 # define EXIM_HAVE_OCSP
83 # define EXIM_NEED_OPENSSL_INIT
85 # if OPENSSL_VERSION_NUMBER >= 0x010000000L \
86 && (OPENSSL_VERSION_NUMBER & 0x0000ff000L) >= 0x000002000L
87 # define EXIM_HAVE_OPENSSL_CHECKHOST
91 #if !defined(LIBRESSL_VERSION_NUMBER) \
92 || LIBRESSL_VERSION_NUMBER >= 0x20010000L
93 # if !defined(OPENSSL_NO_ECDH)
94 # if OPENSSL_VERSION_NUMBER >= 0x0090800fL
95 # define EXIM_HAVE_ECDH
97 # if OPENSSL_VERSION_NUMBER >= 0x10002000L
98 # define EXIM_HAVE_OPENSSL_EC_NIST2NID
103 #ifndef LIBRESSL_VERSION_NUMBER
104 # if OPENSSL_VERSION_NUMBER >= 0x010101000L
105 # define OPENSSL_HAVE_KEYLOG_CB
106 # define OPENSSL_HAVE_NUM_TICKETS
107 # define EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
109 # define OPENSSL_BAD_SRVR_OURCERT
113 #if !defined(EXIM_HAVE_OPENSSL_TLSEXT) && !defined(DISABLE_OCSP)
114 # warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
115 # define DISABLE_OCSP
118 #ifdef EXPERIMENTAL_TLS_RESUME
119 # if OPENSSL_VERSION_NUMBER < 0x0101010L
120 # error OpenSSL version too old for session-resumption
124 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
125 # include <openssl/x509v3.h>
128 #ifndef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
129 # ifndef EXIM_HAVE_OPENSSL_CIPHER_GET_ID
130 # define SSL_CIPHER_get_id(c) (c->id)
132 # ifndef MACRO_PREDEF
133 # include "tls-cipher-stdname.c"
137 /*************************************************
138 * OpenSSL option parse *
139 *************************************************/
141 typedef struct exim_openssl_option {
144 } exim_openssl_option;
145 /* We could use a macro to expand, but we need the ifdef and not all the
146 options document which version they were introduced in. Policylet: include
147 all options unless explicitly for DTLS, let the administrator choose which
150 This list is current as of:
152 Plus SSL_OP_SAFARI_ECDHE_ECDSA_BUG from 2013-June patch/discussion on openssl-dev
153 Plus SSL_OP_NO_TLSv1_3 for 1.1.2-dev
154 Plus SSL_OP_NO_RENEGOTIATION for 1.1.1
156 XXX could we autobuild this list, as with predefined-macros?
157 Seems just parsing ssl.h for SSL_OP_.* would be enough.
158 Also allow a numeric literal?
160 static exim_openssl_option exim_openssl_options[] = {
161 /* KEEP SORTED ALPHABETICALLY! */
163 { US"all", (long) SSL_OP_ALL },
165 #ifdef SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
166 { US"allow_unsafe_legacy_renegotiation", SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION },
168 #ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
169 { US"cipher_server_preference", SSL_OP_CIPHER_SERVER_PREFERENCE },
171 #ifdef SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
172 { US"dont_insert_empty_fragments", SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS },
174 #ifdef SSL_OP_EPHEMERAL_RSA
175 { US"ephemeral_rsa", SSL_OP_EPHEMERAL_RSA },
177 #ifdef SSL_OP_LEGACY_SERVER_CONNECT
178 { US"legacy_server_connect", SSL_OP_LEGACY_SERVER_CONNECT },
180 #ifdef SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER
181 { US"microsoft_big_sslv3_buffer", SSL_OP_MICROSOFT_BIG_SSLV3_BUFFER },
183 #ifdef SSL_OP_MICROSOFT_SESS_ID_BUG
184 { US"microsoft_sess_id_bug", SSL_OP_MICROSOFT_SESS_ID_BUG },
186 #ifdef SSL_OP_MSIE_SSLV2_RSA_PADDING
187 { US"msie_sslv2_rsa_padding", SSL_OP_MSIE_SSLV2_RSA_PADDING },
189 #ifdef SSL_OP_NETSCAPE_CHALLENGE_BUG
190 { US"netscape_challenge_bug", SSL_OP_NETSCAPE_CHALLENGE_BUG },
192 #ifdef SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG
193 { US"netscape_reuse_cipher_change_bug", SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG },
195 #ifdef SSL_OP_NO_COMPRESSION
196 { US"no_compression", SSL_OP_NO_COMPRESSION },
198 #ifdef SSL_OP_NO_RENEGOTIATION
199 { US"no_renegotiation", SSL_OP_NO_RENEGOTIATION },
201 #ifdef SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
202 { US"no_session_resumption_on_renegotiation", SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION },
204 #ifdef SSL_OP_NO_SSLv2
205 { US"no_sslv2", SSL_OP_NO_SSLv2 },
207 #ifdef SSL_OP_NO_SSLv3
208 { US"no_sslv3", SSL_OP_NO_SSLv3 },
210 #ifdef SSL_OP_NO_TICKET
211 { US"no_ticket", SSL_OP_NO_TICKET },
213 #ifdef SSL_OP_NO_TLSv1
214 { US"no_tlsv1", SSL_OP_NO_TLSv1 },
216 #ifdef SSL_OP_NO_TLSv1_1
217 #if SSL_OP_NO_TLSv1_1 == 0x00000400L
218 /* Error in chosen value in 1.0.1a; see first item in CHANGES for 1.0.1b */
219 #warning OpenSSL 1.0.1a uses a bad value for SSL_OP_NO_TLSv1_1, ignoring
221 { US"no_tlsv1_1", SSL_OP_NO_TLSv1_1 },
224 #ifdef SSL_OP_NO_TLSv1_2
225 { US"no_tlsv1_2", SSL_OP_NO_TLSv1_2 },
227 #ifdef SSL_OP_NO_TLSv1_3
228 { US"no_tlsv1_3", SSL_OP_NO_TLSv1_3 },
230 #ifdef SSL_OP_SAFARI_ECDHE_ECDSA_BUG
231 { US"safari_ecdhe_ecdsa_bug", SSL_OP_SAFARI_ECDHE_ECDSA_BUG },
233 #ifdef SSL_OP_SINGLE_DH_USE
234 { US"single_dh_use", SSL_OP_SINGLE_DH_USE },
236 #ifdef SSL_OP_SINGLE_ECDH_USE
237 { US"single_ecdh_use", SSL_OP_SINGLE_ECDH_USE },
239 #ifdef SSL_OP_SSLEAY_080_CLIENT_DH_BUG
240 { US"ssleay_080_client_dh_bug", SSL_OP_SSLEAY_080_CLIENT_DH_BUG },
242 #ifdef SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG
243 { US"sslref2_reuse_cert_type_bug", SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG },
245 #ifdef SSL_OP_TLS_BLOCK_PADDING_BUG
246 { US"tls_block_padding_bug", SSL_OP_TLS_BLOCK_PADDING_BUG },
248 #ifdef SSL_OP_TLS_D5_BUG
249 { US"tls_d5_bug", SSL_OP_TLS_D5_BUG },
251 #ifdef SSL_OP_TLS_ROLLBACK_BUG
252 { US"tls_rollback_bug", SSL_OP_TLS_ROLLBACK_BUG },
257 static int exim_openssl_options_size = nelem(exim_openssl_options);
266 for (struct exim_openssl_option * o = exim_openssl_options;
267 o < exim_openssl_options + nelem(exim_openssl_options); o++)
269 /* Trailing X is workaround for problem with _OPT_OPENSSL_NO_TLSV1
270 being a ".ifdef _OPT_OPENSSL_NO_TLSV1_3" match */
272 spf(buf, sizeof(buf), US"_OPT_OPENSSL_%T_X", o->name);
273 builtin_macro_create(buf);
276 # ifdef EXPERIMENTAL_TLS_RESUME
277 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
279 # ifdef SSL_OP_NO_TLSv1_3
280 builtin_macro_create(US"_HAVE_TLS1_3");
282 # ifdef OPENSSL_BAD_SRVR_OURCERT
283 builtin_macro_create(US"_TLS_BAD_MULTICERT_IN_OURCERT");
285 # ifdef EXIM_HAVE_OCSP
286 builtin_macro_create(US"_HAVE_TLS_OCSP");
287 builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
292 /******************************************************************************/
294 /* Structure for collecting random data for seeding. */
296 typedef struct randstuff {
301 /* Local static variables */
303 static BOOL client_verify_callback_called = FALSE;
304 static BOOL server_verify_callback_called = FALSE;
305 static const uschar *sid_ctx = US"exim";
307 /* We have three different contexts to care about.
309 Simple case: client, `client_ctx`
310 As a client, we can be doing a callout or cut-through delivery while receiving
311 a message. So we have a client context, which should have options initialised
312 from the SMTP Transport. We may also concurrently want to make TLS connections
313 to utility daemons, so client-contexts are allocated and passed around in call
314 args rather than using a gobal.
317 There are two cases: with and without ServerNameIndication from the client.
318 Given TLS SNI, we can be using different keys, certs and various other
319 configuration settings, because they're re-expanded with $tls_sni set. This
320 allows vhosting with TLS. This SNI is sent in the handshake.
321 A client might not send SNI, so we need a fallback, and an initial setup too.
322 So as a server, we start out using `server_ctx`.
323 If SNI is sent by the client, then we as server, mid-negotiation, try to clone
324 `server_sni` from `server_ctx` and then initialise settings by re-expanding
332 } exim_openssl_client_tls_ctx;
334 static SSL_CTX *server_ctx = NULL;
335 static SSL *server_ssl = NULL;
337 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
338 static SSL_CTX *server_sni = NULL;
341 static char ssl_errstring[256];
343 static int ssl_session_timeout = 7200; /* Two hours */
344 static BOOL client_verify_optional = FALSE;
345 static BOOL server_verify_optional = FALSE;
347 static BOOL reexpand_tls_files_for_sni = FALSE;
350 typedef struct ocsp_resp {
351 struct ocsp_resp * next;
352 OCSP_RESPONSE * resp;
355 typedef struct tls_ext_ctx_cb {
361 STACK_OF(X509) *verify_stack; /* chain for verifying the proof */
365 const uschar *file_expanded;
366 ocsp_resplist *olist;
369 X509_STORE *verify_store; /* non-null if status requested */
370 BOOL verify_required;
375 /* these are cached from first expand */
376 uschar *server_cipher_list;
377 /* only passed down to tls_error: */
379 const uschar * verify_cert_hostnames;
380 #ifndef DISABLE_EVENT
381 uschar * event_action;
385 /* should figure out a cleanup of API to handle state preserved per
386 implementation, for various reasons, which can be void * in the APIs.
387 For now, we hack around it. */
388 tls_ext_ctx_cb *client_static_cbinfo = NULL; /*XXX should not use static; multiple concurrent clients! */
389 tls_ext_ctx_cb *server_static_cbinfo = NULL;
392 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
393 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr );
396 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
397 static int tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg);
400 static int tls_server_stapling_cb(SSL *s, void *arg);
405 /* Daemon-called, before every connection, key create/rotate */
406 #ifdef EXPERIMENTAL_TLS_RESUME
407 static void tk_init(void);
408 static int tls_exdata_idx = -1;
412 tls_daemon_init(void)
414 #ifdef EXPERIMENTAL_TLS_RESUME
421 /*************************************************
423 *************************************************/
425 /* Called from lots of places when errors occur before actually starting to do
426 the TLS handshake, that is, while the session is still in clear. Always returns
427 DEFER for a server and FAIL for a client so that most calls can use "return
428 tls_error(...)" to do this processing and then give an appropriate return. A
429 single function is used for both server and client, because it is called from
430 some shared functions.
433 prefix text to include in the logged error
434 host NULL if setting up a server;
435 the connected host if setting up a client
436 msg error message or NULL if we should ask OpenSSL
437 errstr pointer to output error message
439 Returns: OK/DEFER/FAIL
443 tls_error(uschar * prefix, const host_item * host, uschar * msg, uschar ** errstr)
447 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
448 msg = US ssl_errstring;
451 msg = string_sprintf("(%s): %s", prefix, msg);
452 DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
453 if (errstr) *errstr = msg;
454 return host ? FAIL : DEFER;
459 /*************************************************
460 * Callback to generate RSA key *
461 *************************************************/
465 s SSL connection (not used)
469 Returns: pointer to generated key
473 rsa_callback(SSL *s, int export, int keylength)
476 #ifdef EXIM_HAVE_RSA_GENKEY_EX
477 BIGNUM *bn = BN_new();
480 export = export; /* Shut picky compilers up */
481 DEBUG(D_tls) debug_printf("Generating %d bit RSA key...\n", keylength);
483 #ifdef EXIM_HAVE_RSA_GENKEY_EX
484 if ( !BN_set_word(bn, (unsigned long)RSA_F4)
485 || !(rsa_key = RSA_new())
486 || !RSA_generate_key_ex(rsa_key, keylength, bn, NULL)
489 if (!(rsa_key = RSA_generate_key(keylength, RSA_F4, NULL, NULL)))
493 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
494 log_write(0, LOG_MAIN|LOG_PANIC, "TLS error (RSA_generate_key): %s",
506 x509_store_dump_cert_s_names(X509_STORE * store)
508 STACK_OF(X509_OBJECT) * roots= store->objs;
509 static uschar name[256];
511 for (int i= 0; i < sk_X509_OBJECT_num(roots); i++)
513 X509_OBJECT * tmp_obj= sk_X509_OBJECT_value(roots, i);
514 if(tmp_obj->type == X509_LU_X509)
516 X509_NAME * sn = X509_get_subject_name(tmp_obj->data.x509);
517 if (X509_NAME_oneline(sn, CS name, sizeof(name)))
519 name[sizeof(name)-1] = '\0';
520 debug_printf(" %s\n", name);
529 #ifndef DISABLE_EVENT
531 verify_event(tls_support * tlsp, X509 * cert, int depth, const uschar * dn,
532 BOOL *calledp, const BOOL *optionalp, const uschar * what)
538 ev = tlsp == &tls_out ? client_static_cbinfo->event_action : event_action;
541 DEBUG(D_tls) debug_printf("verify_event: %s %d\n", what, depth);
542 old_cert = tlsp->peercert;
543 tlsp->peercert = X509_dup(cert);
544 /* NB we do not bother setting peerdn */
545 if ((yield = event_raise(ev, US"tls:cert", string_sprintf("%d", depth))))
547 log_write(0, LOG_MAIN, "[%s] %s verify denied by event-action: "
548 "depth=%d cert=%s: %s",
549 tlsp == &tls_out ? deliver_host_address : sender_host_address,
550 what, depth, dn, yield);
554 if (old_cert) tlsp->peercert = old_cert; /* restore 1st failing cert */
555 return 1; /* reject (leaving peercert set) */
557 DEBUG(D_tls) debug_printf("Event-action verify failure overridden "
558 "(host in tls_try_verify_hosts)\n");
559 tlsp->verify_override = TRUE;
561 X509_free(tlsp->peercert);
562 tlsp->peercert = old_cert;
568 /*************************************************
569 * Callback for verification *
570 *************************************************/
572 /* The SSL library does certificate verification if set up to do so. This
573 callback has the current yes/no state is in "state". If verification succeeded,
574 we set the certificate-verified flag. If verification failed, what happens
575 depends on whether the client is required to present a verifiable certificate
578 If verification is optional, we change the state to yes, but still log the
579 verification error. For some reason (it really would help to have proper
580 documentation of OpenSSL), this callback function then gets called again, this
581 time with state = 1. We must take care not to set the private verified flag on
582 the second time through.
584 Note: this function is not called if the client fails to present a certificate
585 when asked. We get here only if a certificate has been received. Handling of
586 optional verification for this case is done when requesting SSL to verify, by
587 setting SSL_VERIFY_FAIL_IF_NO_PEER_CERT in the non-optional case.
589 May be called multiple times for different issues with a certificate, even
590 for a given "depth" in the certificate chain.
593 preverify_ok current yes/no state as 1/0
594 x509ctx certificate information.
595 tlsp per-direction (client vs. server) support data
596 calledp has-been-called flag
597 optionalp verification-is-optional flag
599 Returns: 0 if verification should fail, otherwise 1
603 verify_callback(int preverify_ok, X509_STORE_CTX * x509ctx,
604 tls_support * tlsp, BOOL * calledp, BOOL * optionalp)
606 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
607 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
610 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
612 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
613 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
614 tlsp == &tls_out ? deliver_host_address : sender_host_address);
617 dn[sizeof(dn)-1] = '\0';
619 tlsp->verify_override = FALSE;
620 if (preverify_ok == 0)
622 uschar * extra = verify_mode ? string_sprintf(" (during %c-verify for [%s])",
623 *verify_mode, sender_host_address)
625 log_write(0, LOG_MAIN, "[%s] SSL verify error%s: depth=%d error=%s cert=%s",
626 tlsp == &tls_out ? deliver_host_address : sender_host_address,
628 X509_verify_cert_error_string(X509_STORE_CTX_get_error(x509ctx)), dn);
633 tlsp->peercert = X509_dup(cert); /* record failing cert */
634 return 0; /* reject */
636 DEBUG(D_tls) debug_printf("SSL verify failure overridden (host in "
637 "tls_try_verify_hosts)\n");
638 tlsp->verify_override = TRUE;
643 DEBUG(D_tls) debug_printf("SSL verify ok: depth=%d SN=%s\n", depth, dn);
645 if (tlsp == &tls_out && client_static_cbinfo->u_ocsp.client.verify_store)
646 { /* client, wanting stapling */
647 /* Add the server cert's signing chain as the one
648 for the verification of the OCSP stapled information. */
650 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
653 sk_X509_push(client_static_cbinfo->verify_stack, cert);
656 #ifndef DISABLE_EVENT
657 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
658 return 0; /* reject, with peercert set */
663 const uschar * verify_cert_hostnames;
665 if ( tlsp == &tls_out
666 && ((verify_cert_hostnames = client_static_cbinfo->verify_cert_hostnames)))
667 /* client, wanting hostname check */
670 #ifdef EXIM_HAVE_OPENSSL_CHECKHOST
671 # ifndef X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
672 # define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0
674 # ifndef X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS
675 # define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0
678 const uschar * list = verify_cert_hostnames;
681 while ((name = string_nextinlist(&list, &sep, NULL, 0)))
682 if ((rc = X509_check_host(cert, CCS name, 0,
683 X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS
684 | X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS,
689 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
690 tlsp == &tls_out ? deliver_host_address : sender_host_address);
697 if (!tls_is_name_for_cert(verify_cert_hostnames, cert))
700 uschar * extra = verify_mode
701 ? string_sprintf(" (during %c-verify for [%s])",
702 *verify_mode, sender_host_address)
704 log_write(0, LOG_MAIN,
705 "[%s] SSL verify error%s: certificate name mismatch: DN=\"%s\" H=\"%s\"",
706 tlsp == &tls_out ? deliver_host_address : sender_host_address,
707 extra, dn, verify_cert_hostnames);
712 tlsp->peercert = X509_dup(cert); /* record failing cert */
713 return 0; /* reject */
715 DEBUG(D_tls) debug_printf("SSL verify name failure overridden (host in "
716 "tls_try_verify_hosts)\n");
717 tlsp->verify_override = TRUE;
721 #ifndef DISABLE_EVENT
722 if (verify_event(tlsp, cert, depth, dn, calledp, optionalp, US"SSL"))
723 return 0; /* reject, with peercert set */
726 DEBUG(D_tls) debug_printf("SSL%s verify ok: depth=0 SN=%s\n",
727 *calledp ? "" : " authenticated", dn);
731 return 1; /* accept, at least for this level */
735 verify_callback_client(int preverify_ok, X509_STORE_CTX *x509ctx)
737 return verify_callback(preverify_ok, x509ctx, &tls_out,
738 &client_verify_callback_called, &client_verify_optional);
742 verify_callback_server(int preverify_ok, X509_STORE_CTX *x509ctx)
744 return verify_callback(preverify_ok, x509ctx, &tls_in,
745 &server_verify_callback_called, &server_verify_optional);
751 /* This gets called *by* the dane library verify callback, which interposes
755 verify_callback_client_dane(int preverify_ok, X509_STORE_CTX * x509ctx)
757 X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
759 int depth = X509_STORE_CTX_get_error_depth(x509ctx);
760 #ifndef DISABLE_EVENT
761 BOOL dummy_called, optional = FALSE;
764 if (!X509_NAME_oneline(X509_get_subject_name(cert), CS dn, sizeof(dn)))
766 DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n");
767 log_write(0, LOG_MAIN, "[%s] SSL verify error: internal error",
768 deliver_host_address);
771 dn[sizeof(dn)-1] = '\0';
773 DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s depth %d %s\n",
774 preverify_ok ? "ok":"BAD", depth, dn);
776 #ifndef DISABLE_EVENT
777 if (verify_event(&tls_out, cert, depth, dn,
778 &dummy_called, &optional, US"DANE"))
779 return 0; /* reject, with peercert set */
782 if (preverify_ok == 1)
784 tls_out.dane_verified = TRUE;
786 if (client_static_cbinfo->u_ocsp.client.verify_store)
787 { /* client, wanting stapling */
788 /* Add the server cert's signing chain as the one
789 for the verification of the OCSP stapled information. */
791 if (!X509_STORE_add_cert(client_static_cbinfo->u_ocsp.client.verify_store,
794 sk_X509_push(client_static_cbinfo->verify_stack, cert);
800 int err = X509_STORE_CTX_get_error(x509ctx);
802 debug_printf(" - err %d '%s'\n", err, X509_verify_cert_error_string(err));
803 if (err == X509_V_ERR_APPLICATION_VERIFICATION)
809 #endif /*SUPPORT_DANE*/
812 /*************************************************
813 * Information callback *
814 *************************************************/
816 /* The SSL library functions call this from time to time to indicate what they
817 are doing. We copy the string to the debugging output when TLS debugging has
829 info_callback(SSL *s, int where, int ret)
835 if (where & SSL_ST_CONNECT)
836 str = US"SSL_connect";
837 else if (where & SSL_ST_ACCEPT)
838 str = US"SSL_accept";
840 str = US"SSL info (undefined)";
842 if (where & SSL_CB_LOOP)
843 debug_printf("%s: %s\n", str, SSL_state_string_long(s));
844 else if (where & SSL_CB_ALERT)
845 debug_printf("SSL3 alert %s:%s:%s\n",
846 str = where & SSL_CB_READ ? US"read" : US"write",
847 SSL_alert_type_string_long(ret), SSL_alert_desc_string_long(ret));
848 else if (where & SSL_CB_EXIT)
850 debug_printf("%s: failed in %s\n", str, SSL_state_string_long(s));
852 debug_printf("%s: error in %s\n", str, SSL_state_string_long(s));
853 else if (where & SSL_CB_HANDSHAKE_START)
854 debug_printf("%s: hshake start: %s\n", str, SSL_state_string_long(s));
855 else if (where & SSL_CB_HANDSHAKE_DONE)
856 debug_printf("%s: hshake done: %s\n", str, SSL_state_string_long(s));
860 #ifdef OPENSSL_HAVE_KEYLOG_CB
862 keylog_callback(const SSL *ssl, const char *line)
866 DEBUG(D_tls) debug_printf("%.200s\n", line);
867 if (!(filename = getenv("SSLKEYLOGFILE"))) return;
868 if (!(fp = fopen(filename, "a"))) return;
869 fprintf(fp, "%s\n", line);
875 #ifdef EXPERIMENTAL_TLS_RESUME
876 /* Manage the keysets used for encrypting the session tickets, on the server. */
878 typedef struct { /* Session ticket encryption key */
881 const EVP_CIPHER * aes_cipher;
882 uschar aes_key[32]; /* size needed depends on cipher. aes_128 implies 128/8 = 16? */
883 const EVP_MD * hmac_hash;
889 static exim_stek exim_tk; /* current key */
890 static exim_stek exim_tk_old; /* previous key */
895 time_t t = time(NULL);
899 if (exim_tk.renew >= t) return;
900 exim_tk_old = exim_tk;
903 if (f.running_in_test_harness) ssl_session_timeout = 6;
905 DEBUG(D_tls) debug_printf("OpenSSL: %s STEK\n", exim_tk.name[0] ? "rotating" : "creating");
906 if (RAND_bytes(exim_tk.aes_key, sizeof(exim_tk.aes_key)) <= 0) return;
907 if (RAND_bytes(exim_tk.hmac_key, sizeof(exim_tk.hmac_key)) <= 0) return;
908 if (RAND_bytes(exim_tk.name+1, sizeof(exim_tk.name)-1) <= 0) return;
910 exim_tk.name[0] = 'E';
911 exim_tk.aes_cipher = EVP_aes_256_cbc();
912 exim_tk.hmac_hash = EVP_sha256();
913 exim_tk.expire = t + ssl_session_timeout;
914 exim_tk.renew = t + ssl_session_timeout/2;
920 if (!exim_tk.name[0]) return NULL;
925 tk_find(const uschar * name)
927 return memcmp(name, exim_tk.name, sizeof(exim_tk.name)) == 0 ? &exim_tk
928 : memcmp(name, exim_tk_old.name, sizeof(exim_tk_old.name)) == 0 ? &exim_tk_old
932 /* Callback for session tickets, on server */
934 ticket_key_callback(SSL * ssl, uschar key_name[16],
935 uschar * iv, EVP_CIPHER_CTX * ctx, HMAC_CTX * hctx, int enc)
937 tls_support * tlsp = server_static_cbinfo->tlsp;
942 DEBUG(D_tls) debug_printf("ticket_key_callback: create new session\n");
943 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
945 if (RAND_bytes(iv, EVP_MAX_IV_LENGTH) <= 0)
946 return -1; /* insufficient random */
948 if (!(key = tk_current())) /* current key doesn't exist or isn't valid */
949 return 0; /* key couldn't be created */
950 memcpy(key_name, key->name, 16);
951 DEBUG(D_tls) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - time(NULL));
953 /*XXX will want these dependent on the ssl session strength */
954 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
955 key->hmac_hash, NULL);
956 EVP_EncryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
958 DEBUG(D_tls) debug_printf("ticket created\n");
963 time_t now = time(NULL);
965 DEBUG(D_tls) debug_printf("ticket_key_callback: retrieve session\n");
966 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
968 if (!(key = tk_find(key_name)) || key->expire < now)
972 debug_printf("ticket not usable (%s)\n", key ? "expired" : "not found");
973 if (key) debug_printf("STEK expire " TIME_T_FMT "\n", key->expire - now);
978 HMAC_Init_ex(hctx, key->hmac_key, sizeof(key->hmac_key),
979 key->hmac_hash, NULL);
980 EVP_DecryptInit_ex(ctx, key->aes_cipher, NULL, key->aes_key, iv);
982 DEBUG(D_tls) debug_printf("ticket usable, STEK expire " TIME_T_FMT "\n", key->expire - now);
984 /* The ticket lifetime and renewal are the same as the STEK lifetime and
985 renewal, which is overenthusiastic. A factor of, say, 3x longer STEK would
986 be better. To do that we'd have to encode ticket lifetime in the name as
987 we don't yet see the restored session. Could check posthandshake for TLS1.3
988 and trigger a new ticket then, but cannot do that for TLS1.2 */
989 return key->renew < now ? 2 : 1;
996 /*************************************************
997 * Initialize for DH *
998 *************************************************/
1000 /* If dhparam is set, expand it, and load up the parameters for DH encryption.
1003 sctx The current SSL CTX (inbound or outbound)
1004 dhparam DH parameter file or fixed parameter identity string
1005 host connected host, if client; NULL if server
1006 errstr error string pointer
1008 Returns: TRUE if OK (nothing to set up, or setup worked)
1012 init_dh(SSL_CTX *sctx, uschar *dhparam, const host_item *host, uschar ** errstr)
1020 if (!expand_check(dhparam, US"tls_dhparam", &dhexpanded, errstr))
1023 if (!dhexpanded || !*dhexpanded)
1024 bio = BIO_new_mem_buf(CS std_dh_prime_default(), -1);
1025 else if (dhexpanded[0] == '/')
1027 if (!(bio = BIO_new_file(CS dhexpanded, "r")))
1029 tls_error(string_sprintf("could not read dhparams file %s", dhexpanded),
1030 host, US strerror(errno), errstr);
1036 if (Ustrcmp(dhexpanded, "none") == 0)
1038 DEBUG(D_tls) debug_printf("Requested no DH parameters.\n");
1042 if (!(pem = std_dh_prime_named(dhexpanded)))
1044 tls_error(string_sprintf("Unknown standard DH prime \"%s\"", dhexpanded),
1045 host, US strerror(errno), errstr);
1048 bio = BIO_new_mem_buf(CS pem, -1);
1051 if (!(dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL)))
1054 tls_error(string_sprintf("Could not read tls_dhparams \"%s\"", dhexpanded),
1055 host, NULL, errstr);
1059 /* note: our default limit of 2236 is not a multiple of 8; the limit comes from
1060 * an NSS limit, and the GnuTLS APIs handle bit-sizes fine, so we went with
1061 * 2236. But older OpenSSL can only report in bytes (octets), not bits.
1062 * If someone wants to dance at the edge, then they can raise the limit or use
1063 * current libraries. */
1064 #ifdef EXIM_HAVE_OPENSSL_DH_BITS
1065 /* Added in commit 26c79d5641d; `git describe --contains` says OpenSSL_1_1_0-pre1~1022
1066 * This predates OpenSSL_1_1_0 (before a, b, ...) so is in all 1.1.0 */
1067 dh_bitsize = DH_bits(dh);
1069 dh_bitsize = 8 * DH_size(dh);
1072 /* Even if it is larger, we silently return success rather than cause things
1073 * to fail out, so that a too-large DH will not knock out all TLS; it's a
1074 * debatable choice. */
1075 if (dh_bitsize > tls_dh_max_bits)
1078 debug_printf("dhparams file %d bits, is > tls_dh_max_bits limit of %d\n",
1079 dh_bitsize, tls_dh_max_bits);
1083 SSL_CTX_set_tmp_dh(sctx, dh);
1085 debug_printf("Diffie-Hellman initialized from %s with %d-bit prime\n",
1086 dhexpanded ? dhexpanded : US"default", dh_bitsize);
1098 /*************************************************
1099 * Initialize for ECDH *
1100 *************************************************/
1102 /* Load parameters for ECDH encryption.
1104 For now, we stick to NIST P-256 because: it's simple and easy to configure;
1105 it avoids any patent issues that might bite redistributors; despite events in
1106 the news and concerns over curve choices, we're not cryptographers, we're not
1107 pretending to be, and this is "good enough" to be better than no support,
1108 protecting against most adversaries. Given another year or two, there might
1109 be sufficient clarity about a "right" way forward to let us make an informed
1110 decision, instead of a knee-jerk reaction.
1112 Longer-term, we should look at supporting both various named curves and
1113 external files generated with "openssl ecparam", much as we do for init_dh().
1114 We should also support "none" as a value, to explicitly avoid initialisation.
1119 sctx The current SSL CTX (inbound or outbound)
1120 host connected host, if client; NULL if server
1121 errstr error string pointer
1123 Returns: TRUE if OK (nothing to set up, or setup worked)
1127 init_ecdh(SSL_CTX * sctx, host_item * host, uschar ** errstr)
1129 #ifdef OPENSSL_NO_ECDH
1138 if (host) /* No ECDH setup for clients, only for servers */
1141 # ifndef EXIM_HAVE_ECDH
1143 debug_printf("No OpenSSL API to define ECDH parameters, skipping\n");
1147 if (!expand_check(tls_eccurve, US"tls_eccurve", &exp_curve, errstr))
1149 if (!exp_curve || !*exp_curve)
1152 /* "auto" needs to be handled carefully.
1153 * OpenSSL < 1.0.2: we do not select anything, but fallback to prime256v1
1154 * OpenSSL < 1.1.0: we have to call SSL_CTX_set_ecdh_auto
1155 * (openssl/ssl.h defines SSL_CTRL_SET_ECDH_AUTO)
1156 * OpenSSL >= 1.1.0: we do not set anything, the libray does autoselection
1157 * https://github.com/openssl/openssl/commit/fe6ef2472db933f01b59cad82aa925736935984b
1159 if (Ustrcmp(exp_curve, "auto") == 0)
1161 #if OPENSSL_VERSION_NUMBER < 0x10002000L
1162 DEBUG(D_tls) debug_printf(
1163 "ECDH OpenSSL < 1.0.2: temp key parameter settings: overriding \"auto\" with \"prime256v1\"\n");
1164 exp_curve = US"prime256v1";
1166 # if defined SSL_CTRL_SET_ECDH_AUTO
1167 DEBUG(D_tls) debug_printf(
1168 "ECDH OpenSSL 1.0.2+ temp key parameter settings: autoselection\n");
1169 SSL_CTX_set_ecdh_auto(sctx, 1);
1172 DEBUG(D_tls) debug_printf(
1173 "ECDH OpenSSL 1.1.0+ temp key parameter settings: default selection\n");
1179 DEBUG(D_tls) debug_printf("ECDH: curve '%s'\n", exp_curve);
1180 if ( (nid = OBJ_sn2nid (CCS exp_curve)) == NID_undef
1181 # ifdef EXIM_HAVE_OPENSSL_EC_NIST2NID
1182 && (nid = EC_curve_nist2nid(CCS exp_curve)) == NID_undef
1186 tls_error(string_sprintf("Unknown curve name tls_eccurve '%s'", exp_curve),
1187 host, NULL, errstr);
1191 if (!(ecdh = EC_KEY_new_by_curve_name(nid)))
1193 tls_error(US"Unable to create ec curve", host, NULL, errstr);
1197 /* The "tmp" in the name here refers to setting a temporary key
1198 not to the stability of the interface. */
1200 if ((rv = SSL_CTX_set_tmp_ecdh(sctx, ecdh) == 0))
1201 tls_error(string_sprintf("Error enabling '%s' curve", exp_curve), host, NULL, errstr);
1203 DEBUG(D_tls) debug_printf("ECDH: enabled '%s' curve\n", exp_curve);
1208 # endif /*EXIM_HAVE_ECDH*/
1209 #endif /*OPENSSL_NO_ECDH*/
1215 #ifndef DISABLE_OCSP
1216 /*************************************************
1217 * Load OCSP information into state *
1218 *************************************************/
1219 /* Called to load the server OCSP response from the given file into memory, once
1220 caller has determined this is needed. Checks validity. Debugs a message
1223 ASSUMES: single response, for single cert.
1226 sctx the SSL_CTX* to update
1227 cbinfo various parts of session state
1228 filename the filename putatively holding an OCSP response
1229 is_pem file is PEM format; otherwise is DER
1234 ocsp_load_response(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo,
1235 const uschar * filename, BOOL is_pem)
1238 OCSP_RESPONSE * resp;
1239 OCSP_BASICRESP * basic_response;
1240 OCSP_SINGLERESP * single_response;
1241 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1242 STACK_OF(X509) * sk;
1243 unsigned long verify_flags;
1244 int status, reason, i;
1247 debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
1249 if (!(bio = BIO_new_file(CS filename, "rb")))
1251 DEBUG(D_tls) debug_printf("Failed to open OCSP response file \"%s\"\n",
1258 uschar * data, * freep;
1261 if (!PEM_read_bio(bio, &dummy, &dummy, &data, &len))
1263 DEBUG(D_tls) debug_printf("Failed to read PEM file \"%s\"\n",
1267 debug_printf("read pem file\n");
1269 resp = d2i_OCSP_RESPONSE(NULL, CUSS &data, len);
1270 OPENSSL_free(freep);
1273 resp = d2i_OCSP_RESPONSE_bio(bio, NULL);
1278 DEBUG(D_tls) debug_printf("Error reading OCSP response.\n");
1282 if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
1284 DEBUG(D_tls) debug_printf("OCSP response not valid: %s (%d)\n",
1285 OCSP_response_status_str(status), status);
1291 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1292 OCSP_RESPONSE_print(bp, resp, 0); /* extreme debug: stapling content */
1297 if (!(basic_response = OCSP_response_get1_basic(resp)))
1300 debug_printf("OCSP response parse error: unable to extract basic response.\n");
1304 sk = cbinfo->verify_stack;
1305 verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
1307 /* May need to expose ability to adjust those flags?
1308 OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
1309 OCSP_TRUSTOTHER OCSP_NOINTERN */
1311 /* This does a full verify on the OCSP proof before we load it for serving
1312 up; possibly overkill - just date-checks might be nice enough.
1314 OCSP_basic_verify takes a "store" arg, but does not
1315 use it for the chain verification, which is all we do
1316 when OCSP_NOVERIFY is set. The content from the wire
1317 "basic_response" and a cert-stack "sk" are all that is used.
1319 We have a stack, loaded in setup_certs() if tls_verify_certificates
1320 was a file (not a directory, or "system"). It is unfortunate we
1321 cannot used the connection context store, as that would neatly
1322 handle the "system" case too, but there seems to be no library
1323 function for getting a stack from a store.
1324 [ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
1325 We do not free the stack since it could be needed a second time for
1328 Separately we might try to replace using OCSP_basic_verify() - which seems to not
1329 be a public interface into the OpenSSL library (there's no manual entry) -
1330 But what with? We also use OCSP_basic_verify in the client stapling callback.
1331 And there we NEED it; we must verify that status... unless the
1332 library does it for us anyway? */
1334 if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
1338 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1339 debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
1344 /* Here's the simplifying assumption: there's only one response, for the
1345 one certificate we use, and nothing for anything else in a chain. If this
1346 proves false, we need to extract a cert id from our issued cert
1347 (tls_certificate) and use that for OCSP_resp_find_status() (which finds the
1348 right cert in the stack and then calls OCSP_single_get0_status()).
1350 I'm hoping to avoid reworking a bunch more of how we handle state here.
1352 XXX that will change when we add support for (TLS1.3) whole-chain stapling
1355 if (!(single_response = OCSP_resp_get0(basic_response, 0)))
1358 debug_printf("Unable to get first response from OCSP basic response.\n");
1362 status = OCSP_single_get0_status(single_response, &reason, &rev, &thisupd, &nextupd);
1363 if (status != V_OCSP_CERTSTATUS_GOOD)
1365 DEBUG(D_tls) debug_printf("OCSP response bad cert status: %s (%d) %s (%d)\n",
1366 OCSP_cert_status_str(status), status,
1367 OCSP_crl_reason_str(reason), reason);
1371 if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1373 DEBUG(D_tls) debug_printf("OCSP status invalid times.\n");
1378 /* Add the resp to the list used by tls_server_stapling_cb() */
1380 ocsp_resplist ** op = &cbinfo->u_ocsp.server.olist, * oentry;
1381 while (oentry = *op)
1383 *op = oentry = store_get(sizeof(ocsp_resplist), FALSE);
1384 oentry->next = NULL;
1385 oentry->resp = resp;
1390 if (f.running_in_test_harness)
1392 extern char ** environ;
1393 if (environ) for (uschar ** p = USS environ; *p; p++)
1394 if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
1396 DEBUG(D_tls) debug_printf("Supplying known bad OCSP response\n");
1397 goto supply_response;
1405 ocsp_free_response_list(tls_ext_ctx_cb * cbinfo)
1407 for (ocsp_resplist * olist = cbinfo->u_ocsp.server.olist; olist;
1408 olist = olist->next)
1409 OCSP_RESPONSE_free(olist->resp);
1410 cbinfo->u_ocsp.server.olist = NULL;
1412 #endif /*!DISABLE_OCSP*/
1417 /* Create and install a selfsigned certificate, for use in server mode */
1420 tls_install_selfsign(SSL_CTX * sctx, uschar ** errstr)
1428 where = US"allocating pkey";
1429 if (!(pkey = EVP_PKEY_new()))
1432 where = US"allocating cert";
1433 if (!(x509 = X509_new()))
1436 where = US"generating pkey";
1437 if (!(rsa = rsa_callback(NULL, 0, 2048)))
1440 where = US"assigning pkey";
1441 if (!EVP_PKEY_assign_RSA(pkey, rsa))
1444 X509_set_version(x509, 2); /* N+1 - version 3 */
1445 ASN1_INTEGER_set(X509_get_serialNumber(x509), 1);
1446 X509_gmtime_adj(X509_get_notBefore(x509), 0);
1447 X509_gmtime_adj(X509_get_notAfter(x509), (long)60 * 60); /* 1 hour */
1448 X509_set_pubkey(x509, pkey);
1450 name = X509_get_subject_name(x509);
1451 X509_NAME_add_entry_by_txt(name, "C",
1452 MBSTRING_ASC, CUS "UK", -1, -1, 0);
1453 X509_NAME_add_entry_by_txt(name, "O",
1454 MBSTRING_ASC, CUS "Exim Developers", -1, -1, 0);
1455 X509_NAME_add_entry_by_txt(name, "CN",
1456 MBSTRING_ASC, CUS smtp_active_hostname, -1, -1, 0);
1457 X509_set_issuer_name(x509, name);
1459 where = US"signing cert";
1460 if (!X509_sign(x509, pkey, EVP_md5()))
1463 where = US"installing selfsign cert";
1464 if (!SSL_CTX_use_certificate(sctx, x509))
1467 where = US"installing selfsign key";
1468 if (!SSL_CTX_use_PrivateKey(sctx, pkey))
1474 (void) tls_error(where, NULL, NULL, errstr);
1475 if (x509) X509_free(x509);
1476 if (pkey) EVP_PKEY_free(pkey);
1484 tls_add_certfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1487 DEBUG(D_tls) debug_printf("tls_certificate file '%s'\n", file);
1488 if (!SSL_CTX_use_certificate_chain_file(sctx, CS file))
1489 return tls_error(string_sprintf(
1490 "SSL_CTX_use_certificate_chain_file file=%s", file),
1491 cbinfo->host, NULL, errstr);
1496 tls_add_pkeyfile(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo, uschar * file,
1499 DEBUG(D_tls) debug_printf("tls_privatekey file '%s'\n", file);
1500 if (!SSL_CTX_use_PrivateKey_file(sctx, CS file, SSL_FILETYPE_PEM))
1501 return tls_error(string_sprintf(
1502 "SSL_CTX_use_PrivateKey_file file=%s", file), cbinfo->host, NULL, errstr);
1507 /*************************************************
1508 * Expand key and cert file specs *
1509 *************************************************/
1511 /* Called once during tls_init and possibly again during TLS setup, for a
1512 new context, if Server Name Indication was used and tls_sni was seen in
1513 the certificate string.
1516 sctx the SSL_CTX* to update
1517 cbinfo various parts of session state
1518 errstr error string pointer
1520 Returns: OK/DEFER/FAIL
1524 tls_expand_session_files(SSL_CTX * sctx, tls_ext_ctx_cb * cbinfo,
1529 if (!cbinfo->certificate)
1531 if (!cbinfo->is_server) /* client */
1534 if (tls_install_selfsign(sctx, errstr) != OK)
1541 if ( !reexpand_tls_files_for_sni
1542 && ( Ustrstr(cbinfo->certificate, US"tls_sni")
1543 || Ustrstr(cbinfo->certificate, US"tls_in_sni")
1544 || Ustrstr(cbinfo->certificate, US"tls_out_sni")
1546 reexpand_tls_files_for_sni = TRUE;
1548 if (!expand_check(cbinfo->certificate, US"tls_certificate", &expanded, errstr))
1552 if (cbinfo->is_server)
1554 const uschar * file_list = expanded;
1557 #ifndef DISABLE_OCSP
1558 const uschar * olist = cbinfo->u_ocsp.server.file;
1561 BOOL fmt_pem = FALSE;
1564 if (!expand_check(olist, US"tls_ocsp_file", USS &olist, errstr))
1566 if (olist && !*olist)
1569 if ( cbinfo->u_ocsp.server.file_expanded && olist
1570 && (Ustrcmp(olist, cbinfo->u_ocsp.server.file_expanded) == 0))
1572 DEBUG(D_tls) debug_printf(" - value unchanged, using existing values\n");
1577 ocsp_free_response_list(cbinfo);
1578 cbinfo->u_ocsp.server.file_expanded = olist;
1582 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1584 if ((err = tls_add_certfile(sctx, cbinfo, file, errstr)))
1587 #ifndef DISABLE_OCSP
1589 if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
1591 if (Ustrncmp(ofile, US"PEM ", 4) == 0)
1596 else if (Ustrncmp(ofile, US"DER ", 4) == 0)
1601 ocsp_load_response(sctx, cbinfo, ofile, fmt_pem);
1604 DEBUG(D_tls) debug_printf("ran out of ocsp file list\n");
1608 else /* would there ever be a need for multiple client certs? */
1609 if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
1612 if ( cbinfo->privatekey
1613 && !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
1616 /* If expansion was forced to fail, key_expanded will be NULL. If the result
1617 of the expansion is an empty string, ignore it also, and assume the private
1618 key is in the same file as the certificate. */
1620 if (expanded && *expanded)
1621 if (cbinfo->is_server)
1623 const uschar * file_list = expanded;
1627 while (file = string_nextinlist(&file_list, &sep, NULL, 0))
1628 if ((err = tls_add_pkeyfile(sctx, cbinfo, file, errstr)))
1631 else /* would there ever be a need for multiple client certs? */
1632 if ((err = tls_add_pkeyfile(sctx, cbinfo, expanded, errstr)))
1642 /*************************************************
1643 * Callback to handle SNI *
1644 *************************************************/
1646 /* Called when acting as server during the TLS session setup if a Server Name
1647 Indication extension was sent by the client.
1649 API documentation is OpenSSL s_server.c implementation.
1652 s SSL* of the current session
1653 ad unknown (part of OpenSSL API) (unused)
1654 arg Callback of "our" registered data
1656 Returns: SSL_TLSEXT_ERR_{OK,ALERT_WARNING,ALERT_FATAL,NOACK}
1658 XXX might need to change to using ClientHello callback,
1659 per https://www.openssl.org/docs/manmaster/man3/SSL_client_hello_cb_fn.html
1662 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
1664 tls_servername_cb(SSL *s, int *ad ARG_UNUSED, void *arg)
1666 const char *servername = SSL_get_servername(s, TLSEXT_NAMETYPE_host_name);
1667 tls_ext_ctx_cb *cbinfo = (tls_ext_ctx_cb *) arg;
1669 int old_pool = store_pool;
1670 uschar * dummy_errstr;
1673 return SSL_TLSEXT_ERR_OK;
1675 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", servername,
1676 reexpand_tls_files_for_sni ? "" : " (unused for certificate selection)");
1678 /* Make the extension value available for expansion */
1679 store_pool = POOL_PERM;
1680 tls_in.sni = string_copy_taint(US servername, TRUE);
1681 store_pool = old_pool;
1683 if (!reexpand_tls_files_for_sni)
1684 return SSL_TLSEXT_ERR_OK;
1686 /* Can't find an SSL_CTX_clone() or equivalent, so we do it manually;
1687 not confident that memcpy wouldn't break some internal reference counting.
1688 Especially since there's a references struct member, which would be off. */
1690 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
1691 if (!(server_sni = SSL_CTX_new(TLS_server_method())))
1693 if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
1696 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
1697 DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
1701 /* Not sure how many of these are actually needed, since SSL object
1702 already exists. Might even need this selfsame callback, for reneg? */
1704 SSL_CTX_set_info_callback(server_sni, SSL_CTX_get_info_callback(server_ctx));
1705 SSL_CTX_set_mode(server_sni, SSL_CTX_get_mode(server_ctx));
1706 SSL_CTX_set_options(server_sni, SSL_CTX_get_options(server_ctx));
1707 SSL_CTX_set_timeout(server_sni, SSL_CTX_get_timeout(server_ctx));
1708 SSL_CTX_set_tlsext_servername_callback(server_sni, tls_servername_cb);
1709 SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
1711 if ( !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
1712 || !init_ecdh(server_sni, NULL, &dummy_errstr)
1716 if ( cbinfo->server_cipher_list
1717 && !SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list))
1720 #ifndef DISABLE_OCSP
1721 if (cbinfo->u_ocsp.server.file)
1723 SSL_CTX_set_tlsext_status_cb(server_sni, tls_server_stapling_cb);
1724 SSL_CTX_set_tlsext_status_arg(server_sni, cbinfo);
1728 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
1729 verify_callback_server, &dummy_errstr)) != OK)
1732 /* do this after setup_certs, because this can require the certs for verifying
1733 OCSP information. */
1734 if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
1737 DEBUG(D_tls) debug_printf("Switching SSL context.\n");
1738 SSL_set_SSL_CTX(s, server_sni);
1739 return SSL_TLSEXT_ERR_OK;
1741 bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
1743 #endif /* EXIM_HAVE_OPENSSL_TLSEXT */
1748 #ifndef DISABLE_OCSP
1750 /*************************************************
1751 * Callback to handle OCSP Stapling *
1752 *************************************************/
1754 /* Called when acting as server during the TLS session setup if the client
1755 requests OCSP information with a Certificate Status Request.
1757 Documentation via openssl s_server.c and the Apache patch from the OpenSSL
1763 tls_server_stapling_cb(SSL *s, void *arg)
1765 const tls_ext_ctx_cb * cbinfo = (tls_ext_ctx_cb *) arg;
1766 ocsp_resplist * olist = cbinfo->u_ocsp.server.olist;
1767 uschar * response_der; /*XXX blob */
1768 int response_der_len;
1771 debug_printf("Received TLS status request (OCSP stapling); %s response list\n",
1772 olist ? "have" : "lack");
1774 tls_in.ocsp = OCSP_NOT_RESP;
1776 return SSL_TLSEXT_ERR_NOACK;
1778 #ifdef EXIM_HAVE_OPESSL_GET0_SERIAL
1780 const X509 * cert_sent = SSL_get_certificate(s);
1781 const ASN1_INTEGER * cert_serial = X509_get0_serialNumber(cert_sent);
1782 const BIGNUM * cert_bn = ASN1_INTEGER_to_BN(cert_serial, NULL);
1783 const X509_NAME * cert_issuer = X509_get_issuer_name(cert_sent);
1787 for (; olist; olist = olist->next)
1789 OCSP_BASICRESP * bs = OCSP_response_get1_basic(olist->resp);
1790 const OCSP_SINGLERESP * single = OCSP_resp_get0(bs, 0);
1791 const OCSP_CERTID * cid = OCSP_SINGLERESP_get0_id(single);
1792 ASN1_INTEGER * res_cert_serial;
1793 const BIGNUM * resp_bn;
1794 ASN1_OCTET_STRING * res_cert_iNameHash;
1797 (void) OCSP_id_get0_info(&res_cert_iNameHash, NULL, NULL, &res_cert_serial,
1798 (OCSP_CERTID *) cid);
1799 resp_bn = ASN1_INTEGER_to_BN(res_cert_serial, NULL);
1803 debug_printf("cert serial: %s\n", BN_bn2hex(cert_bn));
1804 debug_printf("resp serial: %s\n", BN_bn2hex(resp_bn));
1807 if (BN_cmp(cert_bn, resp_bn) == 0)
1809 DEBUG(D_tls) debug_printf("matched serial for ocsp\n");
1811 /*XXX TODO: check the rest of the list for duplicate matches.
1812 If any, need to also check the Issuer Name hash.
1813 Without this, we will provide the wrong status in the case of
1818 DEBUG(D_tls) debug_printf("not match serial for ocsp\n");
1822 DEBUG(D_tls) debug_printf("failed to find match for ocsp\n");
1823 return SSL_TLSEXT_ERR_NOACK;
1829 DEBUG(D_tls) debug_printf("OpenSSL version too early to support multi-leaf OCSP\n");
1830 return SSL_TLSEXT_ERR_NOACK;
1834 /*XXX could we do the i2d earlier, rather than during the callback? */
1835 response_der = NULL;
1836 response_der_len = i2d_OCSP_RESPONSE(olist->resp, &response_der);
1837 if (response_der_len <= 0)
1838 return SSL_TLSEXT_ERR_NOACK;
1840 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
1841 tls_in.ocsp = OCSP_VFIED;
1842 return SSL_TLSEXT_ERR_OK;
1847 time_print(BIO * bp, const char * str, ASN1_GENERALIZEDTIME * time)
1849 BIO_printf(bp, "\t%s: ", str);
1850 ASN1_GENERALIZEDTIME_print(bp, time);
1855 tls_client_stapling_cb(SSL *s, void *arg)
1857 tls_ext_ctx_cb * cbinfo = arg;
1858 const unsigned char * p;
1860 OCSP_RESPONSE * rsp;
1861 OCSP_BASICRESP * bs;
1864 DEBUG(D_tls) debug_printf("Received TLS status callback (OCSP stapling):\n");
1865 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
1868 /* Expect this when we requested ocsp but got none */
1869 if (cbinfo->u_ocsp.client.verify_required && LOGGING(tls_cipher))
1870 log_write(0, LOG_MAIN, "Required TLS certificate status not received");
1872 DEBUG(D_tls) debug_printf(" null\n");
1873 return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
1876 if (!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
1878 tls_out.ocsp = OCSP_FAILED; /*XXX should use tlsp-> to permit concurrent outbound */
1879 if (LOGGING(tls_cipher))
1880 log_write(0, LOG_MAIN, "Received TLS cert status response, parse error");
1882 DEBUG(D_tls) debug_printf(" parse error\n");
1886 if (!(bs = OCSP_response_get1_basic(rsp)))
1888 tls_out.ocsp = OCSP_FAILED;
1889 if (LOGGING(tls_cipher))
1890 log_write(0, LOG_MAIN, "Received TLS cert status response, error parsing response");
1892 DEBUG(D_tls) debug_printf(" error parsing response\n");
1893 OCSP_RESPONSE_free(rsp);
1897 /* We'd check the nonce here if we'd put one in the request. */
1898 /* However that would defeat cacheability on the server so we don't. */
1900 /* This section of code reworked from OpenSSL apps source;
1901 The OpenSSL Project retains copyright:
1902 Copyright (c) 1999 The OpenSSL Project. All rights reserved.
1906 #ifndef EXIM_HAVE_OCSP_RESP_COUNT
1907 STACK_OF(OCSP_SINGLERESP) * sresp = bs->tbsResponseData->responses;
1910 DEBUG(D_tls) bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
1912 /*OCSP_RESPONSE_print(bp, rsp, 0); extreme debug: stapling content */
1914 /* Use the chain that verified the server cert to verify the stapled info */
1915 /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
1917 if ((i = OCSP_basic_verify(bs, cbinfo->verify_stack,
1918 cbinfo->u_ocsp.client.verify_store, OCSP_NOEXPLICIT)) <= 0)
1919 if (ERR_peek_error())
1921 tls_out.ocsp = OCSP_FAILED;
1922 if (LOGGING(tls_cipher)) log_write(0, LOG_MAIN,
1923 "Received TLS cert status response, itself unverifiable: %s",
1924 ERR_reason_error_string(ERR_peek_error()));
1925 BIO_printf(bp, "OCSP response verify failure\n");
1926 ERR_print_errors(bp);
1927 OCSP_RESPONSE_print(bp, rsp, 0);
1931 DEBUG(D_tls) debug_printf("no explicit trust for OCSP signing"
1932 " in the root CA certificate; ignoring\n");
1934 DEBUG(D_tls) debug_printf("OCSP response well-formed and signed OK\n");
1936 /*XXX So we have a good stapled OCSP status. How do we know
1937 it is for the cert of interest? OpenSSL 1.1.0 has a routine
1938 OCSP_resp_find_status() which matches on a cert id, which presumably
1939 we should use. Making an id needs OCSP_cert_id_new(), which takes
1940 issuerName, issuerKey, serialNumber. Are they all in the cert?
1942 For now, carry on blindly accepting the resp. */
1945 #ifdef EXIM_HAVE_OCSP_RESP_COUNT
1946 OCSP_resp_count(bs) - 1;
1948 sk_OCSP_SINGLERESP_num(sresp) - 1;
1952 OCSP_SINGLERESP * single = OCSP_resp_get0(bs, idx);
1954 ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
1956 /*XXX so I can see putting a loop in here to handle a rsp with >1 singleresp
1957 - but what happens with a GnuTLS-style input?
1959 we could do with a debug label for each singleresp
1960 - it has a certID with a serialNumber, but I see no API to get that
1962 status = OCSP_single_get0_status(single, &reason, &rev,
1963 &thisupd, &nextupd);
1965 DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
1966 DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
1967 if (!OCSP_check_validity(thisupd, nextupd,
1968 EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
1970 tls_out.ocsp = OCSP_FAILED;
1971 DEBUG(D_tls) ERR_print_errors(bp);
1972 log_write(0, LOG_MAIN, "Server OSCP dates invalid");
1976 DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
1977 OCSP_cert_status_str(status));
1980 case V_OCSP_CERTSTATUS_GOOD:
1981 continue; /* the idx loop */
1982 case V_OCSP_CERTSTATUS_REVOKED:
1983 log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
1984 reason != -1 ? "; reason: " : "",
1985 reason != -1 ? OCSP_crl_reason_str(reason) : "");
1986 DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
1989 log_write(0, LOG_MAIN,
1990 "Server certificate status unknown, in OCSP stapling");
1998 tls_out.ocsp = OCSP_VFIED;
2002 tls_out.ocsp = OCSP_FAILED;
2003 i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
2008 OCSP_RESPONSE_free(rsp);
2011 #endif /*!DISABLE_OCSP*/
2014 /*************************************************
2015 * Initialize for TLS *
2016 *************************************************/
2019 tls_openssl_init(void)
2021 #ifdef EXIM_NEED_OPENSSL_INIT
2022 SSL_load_error_strings(); /* basic set up */
2023 OpenSSL_add_ssl_algorithms();
2026 #if defined(EXIM_HAVE_SHA256) && !defined(OPENSSL_AUTO_SHA256)
2027 /* SHA256 is becoming ever more popular. This makes sure it gets added to the
2028 list of available digests. */
2029 EVP_add_digest(EVP_sha256());
2035 /* Called from both server and client code, to do preliminary initialization
2036 of the library. We allocate and return a context structure.
2039 ctxp returned SSL context
2040 host connected host, if client; NULL if server
2041 dhparam DH parameter file
2042 certificate certificate file
2043 privatekey private key
2044 ocsp_file file of stapling info (server); flag for require ocsp (client)
2045 addr address if client; NULL if server (for some randomness)
2046 cbp place to put allocated callback context
2047 errstr error string pointer
2049 Returns: OK/DEFER/FAIL
2053 tls_init(SSL_CTX **ctxp, host_item *host, uschar *dhparam, uschar *certificate,
2055 #ifndef DISABLE_OCSP
2058 address_item *addr, tls_ext_ctx_cb ** cbp,
2065 tls_ext_ctx_cb * cbinfo;
2067 cbinfo = store_malloc(sizeof(tls_ext_ctx_cb));
2068 cbinfo->tlsp = tlsp;
2069 cbinfo->certificate = certificate;
2070 cbinfo->privatekey = privatekey;
2071 cbinfo->is_server = host==NULL;
2072 #ifndef DISABLE_OCSP
2073 cbinfo->verify_stack = NULL;
2076 cbinfo->u_ocsp.server.file = ocsp_file;
2077 cbinfo->u_ocsp.server.file_expanded = NULL;
2078 cbinfo->u_ocsp.server.olist = NULL;
2081 cbinfo->u_ocsp.client.verify_store = NULL;
2083 cbinfo->dhparam = dhparam;
2084 cbinfo->server_cipher_list = NULL;
2085 cbinfo->host = host;
2086 #ifndef DISABLE_EVENT
2087 cbinfo->event_action = NULL;
2092 /* Create a context.
2093 The OpenSSL docs in 1.0.1b have not been updated to clarify TLS variant
2094 negotiation in the different methods; as far as I can tell, the only
2095 *_{server,client}_method which allows negotiation is SSLv23, which exists even
2096 when OpenSSL is built without SSLv2 support.
2097 By disabling with openssl_options, we can let admins re-enable with the
2100 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
2101 if (!(ctx = SSL_CTX_new(host ? TLS_client_method() : TLS_server_method())))
2103 if (!(ctx = SSL_CTX_new(host ? SSLv23_client_method() : SSLv23_server_method())))
2105 return tls_error(US"SSL_CTX_new", host, NULL, errstr);
2107 /* It turns out that we need to seed the random number generator this early in
2108 order to get the full complement of ciphers to work. It took me roughly a day
2109 of work to discover this by experiment.
2111 On systems that have /dev/urandom, SSL may automatically seed itself from
2112 there. Otherwise, we have to make something up as best we can. Double check
2118 gettimeofday(&r.tv, NULL);
2121 RAND_seed(US (&r), sizeof(r));
2122 RAND_seed(US big_buffer, big_buffer_size);
2123 if (addr != NULL) RAND_seed(US addr, sizeof(addr));
2126 return tls_error(US"RAND_status", host,
2127 US"unable to seed random number generator", errstr);
2130 /* Set up the information callback, which outputs if debugging is at a suitable
2135 SSL_CTX_set_info_callback(ctx, (void (*)())info_callback);
2136 #if defined(EXIM_HAVE_OPESSL_TRACE) && !defined(OPENSSL_NO_SSL_TRACE)
2137 /* this needs a debug build of OpenSSL */
2138 SSL_CTX_set_msg_callback(ctx, (void (*)())SSL_trace);
2140 #ifdef OPENSSL_HAVE_KEYLOG_CB
2141 SSL_CTX_set_keylog_callback(ctx, (void (*)())keylog_callback);
2145 /* Automatically re-try reads/writes after renegotiation. */
2146 (void) SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
2148 /* Apply administrator-supplied work-arounds.
2149 Historically we applied just one requested option,
2150 SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS, but when bug 994 requested a second, we
2151 moved to an administrator-controlled list of options to specify and
2152 grandfathered in the first one as the default value for "openssl_options".
2154 No OpenSSL version number checks: the options we accept depend upon the
2155 availability of the option value macros from OpenSSL. */
2157 if (!tls_openssl_options_parse(openssl_options, &init_options))
2158 return tls_error(US"openssl_options parsing failed", host, NULL, errstr);
2160 #ifdef EXPERIMENTAL_TLS_RESUME
2161 tlsp->resumption = RESUME_SUPPORTED;
2165 #ifdef EXPERIMENTAL_TLS_RESUME
2166 /* Should the server offer session resumption? */
2167 if (!host && verify_check_host(&tls_resumption_hosts) == OK)
2169 DEBUG(D_tls) debug_printf("tls_resumption_hosts overrides openssl_options\n");
2170 init_options &= ~SSL_OP_NO_TICKET;
2171 tlsp->resumption |= RESUME_SERVER_TICKET; /* server will give ticket on request */
2172 tlsp->host_resumable = TRUE;
2176 DEBUG(D_tls) debug_printf("setting SSL CTX options: %#lx\n", init_options);
2177 if (!(SSL_CTX_set_options(ctx, init_options)))
2178 return tls_error(string_sprintf(
2179 "SSL_CTX_set_option(%#lx)", init_options), host, NULL, errstr);
2182 DEBUG(D_tls) debug_printf("no SSL CTX options to set\n");
2184 /* We'd like to disable session cache unconditionally, but foolish Outlook
2185 Express clients then give up the first TLS connection and make a second one
2186 (which works). Only when there is an IMAP service on the same machine.
2187 Presumably OE is trying to use the cache for A on B. Leave it enabled for
2188 now, until we work out a decent way of presenting control to the config. It
2189 will never be used because we use a new context every time. */
2191 (void) SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_OFF);
2194 /* Initialize with DH parameters if supplied */
2195 /* Initialize ECDH temp key parameter selection */
2197 if ( !init_dh(ctx, dhparam, host, errstr)
2198 || !init_ecdh(ctx, host, errstr)
2202 /* Set up certificate and key (and perhaps OCSP info) */
2204 if ((rc = tls_expand_session_files(ctx, cbinfo, errstr)) != OK)
2207 /* If we need to handle SNI or OCSP, do so */
2209 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
2210 # ifndef DISABLE_OCSP
2211 if (!(cbinfo->verify_stack = sk_X509_new_null()))
2213 DEBUG(D_tls) debug_printf("failed to create stack for stapling verify\n");
2218 if (!host) /* server */
2220 # ifndef DISABLE_OCSP
2221 /* We check u_ocsp.server.file, not server.olist, because we care about if
2222 the option exists, not what the current expansion might be, as SNI might
2223 change the certificate and OCSP file in use between now and the time the
2224 callback is invoked. */
2225 if (cbinfo->u_ocsp.server.file)
2227 SSL_CTX_set_tlsext_status_cb(ctx, tls_server_stapling_cb);
2228 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2231 /* We always do this, so that $tls_sni is available even if not used in
2233 SSL_CTX_set_tlsext_servername_callback(ctx, tls_servername_cb);
2234 SSL_CTX_set_tlsext_servername_arg(ctx, cbinfo);
2236 # ifndef DISABLE_OCSP
2238 if(ocsp_file) /* wanting stapling */
2240 if (!(cbinfo->u_ocsp.client.verify_store = X509_STORE_new()))
2242 DEBUG(D_tls) debug_printf("failed to create store for stapling verify\n");
2245 SSL_CTX_set_tlsext_status_cb(ctx, tls_client_stapling_cb);
2246 SSL_CTX_set_tlsext_status_arg(ctx, cbinfo);
2251 cbinfo->verify_cert_hostnames = NULL;
2253 #ifdef EXIM_HAVE_EPHEM_RSA_KEX
2254 /* Set up the RSA callback */
2255 SSL_CTX_set_tmp_rsa_callback(ctx, rsa_callback);
2258 /* Finally, set the session cache timeout, and we are done.
2259 The period appears to be also used for (server-generated) session tickets */
2261 SSL_CTX_set_timeout(ctx, ssl_session_timeout);
2262 DEBUG(D_tls) debug_printf("Initialized TLS\n");
2273 /*************************************************
2274 * Get name of cipher in use *
2275 *************************************************/
2278 Argument: pointer to an SSL structure for the connection
2279 pointer to number of bits for cipher
2280 Returns: pointer to allocated string in perm-pool
2284 construct_cipher_name(SSL * ssl, int * bits)
2286 int pool = store_pool;
2287 /* With OpenSSL 1.0.0a, 'c' needs to be const but the documentation doesn't
2288 yet reflect that. It should be a safe change anyway, even 0.9.8 versions have
2289 the accessor functions use const in the prototype. */
2291 const uschar * ver = CUS SSL_get_version(ssl);
2292 const SSL_CIPHER * c = (const SSL_CIPHER *) SSL_get_current_cipher(ssl);
2295 SSL_CIPHER_get_bits(c, bits);
2297 store_pool = POOL_PERM;
2298 s = string_sprintf("%s:%s:%u", ver, SSL_CIPHER_get_name(c), *bits);
2300 DEBUG(D_tls) debug_printf("Cipher: %s\n", s);
2305 /* Get IETF-standard name for ciphersuite.
2306 Argument: pointer to an SSL structure for the connection
2307 Returns: pointer to string
2310 static const uschar *
2311 cipher_stdname_ssl(SSL * ssl)
2313 #ifdef EXIM_HAVE_OPENSSL_CIPHER_STD_NAME
2314 return CUS SSL_CIPHER_standard_name(SSL_get_current_cipher(ssl));
2316 ushort id = 0xffff & SSL_CIPHER_get_id(SSL_get_current_cipher(ssl));
2317 return cipher_stdname(id >> 8, id & 0xff);
2323 peer_cert(SSL * ssl, tls_support * tlsp, uschar * peerdn, unsigned siz)
2325 /*XXX we might consider a list-of-certs variable for the cert chain.
2326 SSL_get_peer_cert_chain(SSL*). We'd need a new variable type and support
2327 in list-handling functions, also consider the difference between the entire
2328 chain and the elements sent by the peer. */
2330 tlsp->peerdn = NULL;
2332 /* Will have already noted peercert on a verify fail; possibly not the leaf */
2333 if (!tlsp->peercert)
2334 tlsp->peercert = SSL_get_peer_certificate(ssl);
2335 /* Beware anonymous ciphers which lead to server_cert being NULL */
2337 if (!X509_NAME_oneline(X509_get_subject_name(tlsp->peercert), CS peerdn, siz))
2338 { DEBUG(D_tls) debug_printf("X509_NAME_oneline() error\n"); }
2341 int oldpool = store_pool;
2343 peerdn[siz-1] = '\0'; /* paranoia */
2344 store_pool = POOL_PERM;
2345 tlsp->peerdn = string_copy(peerdn);
2346 store_pool = oldpool;
2348 /* We used to set CV in the cert-verify callbacks (either plain or dane)
2349 but they don't get called on session-resumption. So use the official
2350 interface, which uses the resumed value. Unfortunately this claims verified
2351 when it actually failed but we're in try-verify mode, due to us wanting the
2352 knowlege that it failed so needing to have the callback and forcing a
2353 permissive return. If we don't force it, the TLS startup is failed.
2354 The extra bit of information is set in verify_override in the cb, stashed
2355 for resumption next to the TLS session, and used here. */
2357 if (!tlsp->verify_override)
2358 tlsp->certificate_verified =
2360 tlsp->dane_verified ||
2362 SSL_get_verify_result(ssl) == X509_V_OK;
2370 /*************************************************
2371 * Set up for verifying certificates *
2372 *************************************************/
2374 #ifndef DISABLE_OCSP
2375 /* Load certs from file, return TRUE on success */
2378 chain_from_pem_file(const uschar * file, STACK_OF(X509) * verify_stack)
2383 while (sk_X509_num(verify_stack) > 0)
2384 X509_free(sk_X509_pop(verify_stack));
2386 if (!(bp = BIO_new_file(CS file, "r"))) return FALSE;
2387 while ((x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
2388 sk_X509_push(verify_stack, x);
2396 /* Called by both client and server startup; on the server possibly
2397 repeated after a Server Name Indication.
2400 sctx SSL_CTX* to initialise
2401 certs certs file or NULL
2402 crl CRL file or NULL
2403 host NULL in a server; the remote host in a client
2404 optional TRUE if called from a server for a host in tls_try_verify_hosts;
2405 otherwise passed as FALSE
2406 cert_vfy_cb Callback function for certificate verification
2407 errstr error string pointer
2409 Returns: OK/DEFER/FAIL
2413 setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host, BOOL optional,
2414 int (*cert_vfy_cb)(int, X509_STORE_CTX *), uschar ** errstr)
2416 uschar *expcerts, *expcrl;
2418 if (!expand_check(certs, US"tls_verify_certificates", &expcerts, errstr))
2420 DEBUG(D_tls) debug_printf("tls_verify_certificates: %s\n", expcerts);
2422 if (expcerts && *expcerts)
2424 /* Tell the library to use its compiled-in location for the system default
2425 CA bundle. Then add the ones specified in the config, if any. */
2427 if (!SSL_CTX_set_default_verify_paths(sctx))
2428 return tls_error(US"SSL_CTX_set_default_verify_paths", host, NULL, errstr);
2430 if (Ustrcmp(expcerts, "system") != 0)
2432 struct stat statbuf;
2434 if (Ustat(expcerts, &statbuf) < 0)
2436 log_write(0, LOG_MAIN|LOG_PANIC,
2437 "failed to stat %s for certificates", expcerts);
2443 if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
2444 { file = NULL; dir = expcerts; }
2447 file = expcerts; dir = NULL;
2448 #ifndef DISABLE_OCSP
2449 /* In the server if we will be offering an OCSP proof, load chain from
2450 file for verifying the OCSP proof at load time. */
2452 /*XXX Glitch! The file here is tls_verify_certs: the chain for verifying the client cert.
2453 This is inconsistent with the need to verify the OCSP proof of the server cert.
2457 && statbuf.st_size > 0
2458 && server_static_cbinfo->u_ocsp.server.file
2459 && !chain_from_pem_file(file, server_static_cbinfo->verify_stack)
2462 log_write(0, LOG_MAIN|LOG_PANIC,
2463 "failed to load cert chain from %s", file);
2469 /* If a certificate file is empty, the next function fails with an
2470 unhelpful error message. If we skip it, we get the correct behaviour (no
2471 certificates are recognized, but the error message is still misleading (it
2472 says no certificate was supplied). But this is better. */
2474 if ( (!file || statbuf.st_size > 0)
2475 && !SSL_CTX_load_verify_locations(sctx, CS file, CS dir))
2476 return tls_error(US"SSL_CTX_load_verify_locations", host, NULL, errstr);
2478 /* Load the list of CAs for which we will accept certs, for sending
2479 to the client. This is only for the one-file tls_verify_certificates
2481 If a list isn't loaded into the server, but some verify locations are set,
2482 the server end appears to make a wildcard request for client certs.
2483 Meanwhile, the client library as default behaviour *ignores* the list
2484 we send over the wire - see man SSL_CTX_set_client_cert_cb.
2485 Because of this, and that the dir variant is likely only used for
2486 the public-CA bundle (not for a private CA), not worth fixing. */
2490 STACK_OF(X509_NAME) * names = SSL_load_client_CA_file(CS file);
2492 SSL_CTX_set_client_CA_list(sctx, names);
2493 DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n",
2494 sk_X509_NAME_num(names));
2499 /* Handle a certificate revocation list. */
2501 #if OPENSSL_VERSION_NUMBER > 0x00907000L
2503 /* This bit of code is now the version supplied by Lars Mainka. (I have
2504 merely reformatted it into the Exim code style.)
2506 "From here I changed the code to add support for multiple crl's
2507 in pem format in one file or to support hashed directory entries in
2508 pem format instead of a file. This method now uses the library function
2509 X509_STORE_load_locations to add the CRL location to the SSL context.
2510 OpenSSL will then handle the verify against CA certs and CRLs by
2511 itself in the verify callback." */
2513 if (!expand_check(crl, US"tls_crl", &expcrl, errstr)) return DEFER;
2514 if (expcrl && *expcrl)
2516 struct stat statbufcrl;
2517 if (Ustat(expcrl, &statbufcrl) < 0)
2519 log_write(0, LOG_MAIN|LOG_PANIC,
2520 "failed to stat %s for certificates revocation lists", expcrl);
2525 /* is it a file or directory? */
2527 X509_STORE *cvstore = SSL_CTX_get_cert_store(sctx);
2528 if ((statbufcrl.st_mode & S_IFMT) == S_IFDIR)
2532 DEBUG(D_tls) debug_printf("SSL CRL value is a directory %s\n", dir);
2538 DEBUG(D_tls) debug_printf("SSL CRL value is a file %s\n", file);
2540 if (X509_STORE_load_locations(cvstore, CS file, CS dir) == 0)
2541 return tls_error(US"X509_STORE_load_locations", host, NULL, errstr);
2543 /* setting the flags to check against the complete crl chain */
2545 X509_STORE_set_flags(cvstore,
2546 X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
2550 #endif /* OPENSSL_VERSION_NUMBER > 0x00907000L */
2552 /* If verification is optional, don't fail if no certificate */
2554 SSL_CTX_set_verify(sctx,
2555 SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
2564 /*************************************************
2565 * Start a TLS session in a server *
2566 *************************************************/
2568 /* This is called when Exim is running as a server, after having received
2569 the STARTTLS command. It must respond to that command, and then negotiate
2573 require_ciphers allowed ciphers
2574 errstr pointer to error message
2576 Returns: OK on success
2577 DEFER for errors before the start of the negotiation
2578 FAIL for errors during the negotiation; the server can't
2583 tls_server_start(const uschar * require_ciphers, uschar ** errstr)
2586 uschar * expciphers;
2587 tls_ext_ctx_cb * cbinfo;
2588 static uschar peerdn[256];
2590 /* Check for previous activation */
2592 if (tls_in.active.sock >= 0)
2594 tls_error(US"STARTTLS received after TLS started", NULL, US"", errstr);
2595 smtp_printf("554 Already in TLS\r\n", FALSE);
2599 /* Initialize the SSL library. If it fails, it will already have logged
2602 rc = tls_init(&server_ctx, NULL, tls_dhparam, tls_certificate, tls_privatekey,
2603 #ifndef DISABLE_OCSP
2606 NULL, &server_static_cbinfo, &tls_in, errstr);
2607 if (rc != OK) return rc;
2608 cbinfo = server_static_cbinfo;
2610 if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers, errstr))
2613 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
2614 were historically separated by underscores. So that I can use either form in my
2615 tests, and also for general convenience, we turn underscores into hyphens here.
2617 XXX SSL_CTX_set_cipher_list() is replaced by SSL_CTX_set_ciphersuites()
2618 for TLS 1.3 . Since we do not call it at present we get the default list:
2619 TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256
2624 for (uschar * s = expciphers; *s; s++ ) if (*s == '_') *s = '-';
2625 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
2626 if (!SSL_CTX_set_cipher_list(server_ctx, CS expciphers))
2627 return tls_error(US"SSL_CTX_set_cipher_list", NULL, NULL, errstr);
2628 cbinfo->server_cipher_list = expciphers;
2631 /* If this is a host for which certificate verification is mandatory or
2632 optional, set up appropriately. */
2634 tls_in.certificate_verified = FALSE;
2636 tls_in.dane_verified = FALSE;
2638 server_verify_callback_called = FALSE;
2640 if (verify_check_host(&tls_verify_hosts) == OK)
2642 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2643 FALSE, verify_callback_server, errstr);
2644 if (rc != OK) return rc;
2645 server_verify_optional = FALSE;
2647 else if (verify_check_host(&tls_try_verify_hosts) == OK)
2649 rc = setup_certs(server_ctx, tls_verify_certificates, tls_crl, NULL,
2650 TRUE, verify_callback_server, errstr);
2651 if (rc != OK) return rc;
2652 server_verify_optional = TRUE;
2655 #ifdef EXPERIMENTAL_TLS_RESUME
2656 SSL_CTX_set_tlsext_ticket_key_cb(server_ctx, ticket_key_callback);
2657 /* despite working, appears to always return failure, so ignoring */
2659 #ifdef OPENSSL_HAVE_NUM_TICKETS
2660 # ifdef EXPERIMENTAL_TLS_RESUME
2661 SSL_CTX_set_num_tickets(server_ctx, tls_in.host_resumable ? 1 : 0);
2663 SSL_CTX_set_num_tickets(server_ctx, 0); /* send no TLS1.3 stateful-tickets */
2668 /* Prepare for new connection */
2670 if (!(server_ssl = SSL_new(server_ctx)))
2671 return tls_error(US"SSL_new", NULL, NULL, errstr);
2673 /* Warning: we used to SSL_clear(ssl) here, it was removed.
2675 * With the SSL_clear(), we get strange interoperability bugs with
2676 * OpenSSL 1.0.1b and TLS1.1/1.2. It looks as though this may be a bug in
2677 * OpenSSL itself, as a clear should not lead to inability to follow protocols.
2679 * The SSL_clear() call is to let an existing SSL* be reused, typically after
2680 * session shutdown. In this case, we have a brand new object and there's no
2681 * obvious reason to immediately clear it. I'm guessing that this was
2682 * originally added because of incomplete initialisation which the clear fixed,
2683 * in some historic release.
2686 /* Set context and tell client to go ahead, except in the case of TLS startup
2687 on connection, where outputting anything now upsets the clients and tends to
2688 make them disconnect. We need to have an explicit fflush() here, to force out
2689 the response. Other smtp_printf() calls do not need it, because in non-TLS
2690 mode, the fflush() happens when smtp_getc() is called. */
2692 SSL_set_session_id_context(server_ssl, sid_ctx, Ustrlen(sid_ctx));
2693 if (!tls_in.on_connect)
2695 smtp_printf("220 TLS go ahead\r\n", FALSE);
2699 /* Now negotiate the TLS session. We put our own timer on it, since it seems
2700 that the OpenSSL library doesn't. */
2702 SSL_set_wfd(server_ssl, fileno(smtp_out));
2703 SSL_set_rfd(server_ssl, fileno(smtp_in));
2704 SSL_set_accept_state(server_ssl);
2706 DEBUG(D_tls) debug_printf("Calling SSL_accept\n");
2708 sigalrm_seen = FALSE;
2709 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
2710 rc = SSL_accept(server_ssl);
2715 int error = SSL_get_error(server_ssl, rc);
2718 case SSL_ERROR_NONE:
2721 case SSL_ERROR_ZERO_RETURN:
2722 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
2723 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2725 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
2726 SSL_shutdown(server_ssl);
2728 tls_close(NULL, TLS_NO_SHUTDOWN);
2731 /* Handle genuine errors */
2734 uschar * s = US"SSL_accept";
2735 unsigned long e = ERR_peek_error();
2736 if (ERR_GET_REASON(e) == SSL_R_WRONG_VERSION_NUMBER)
2737 s = string_sprintf("%s (%s)", s, SSL_get_version(server_ssl));
2738 (void) tls_error(s, NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2743 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
2744 if (error == SSL_ERROR_SYSCALL)
2748 *errstr = US"SSL_accept: TCP connection closed by peer";
2751 DEBUG(D_tls) debug_printf(" - syscall %s\n", strerror(errno));
2753 (void) tls_error(US"SSL_accept", NULL, sigalrm_seen ? US"timed out" : NULL, errstr);
2758 DEBUG(D_tls) debug_printf("SSL_accept was successful\n");
2759 ERR_clear_error(); /* Even success can leave errors in the stack. Seen with
2760 anon-authentication ciphersuite negotiated. */
2762 #ifdef EXPERIMENTAL_TLS_RESUME
2763 if (SSL_session_reused(server_ssl))
2765 tls_in.resumption |= RESUME_USED;
2766 DEBUG(D_tls) debug_printf("Session reused\n");
2770 /* TLS has been set up. Adjust the input functions to read via TLS,
2771 and initialize things. */
2773 peer_cert(server_ssl, &tls_in, peerdn, sizeof(peerdn));
2775 tls_in.cipher = construct_cipher_name(server_ssl, &tls_in.bits);
2776 tls_in.cipher_stdname = cipher_stdname_ssl(server_ssl);
2781 if (SSL_get_shared_ciphers(server_ssl, CS buf, sizeof(buf)))
2782 debug_printf("Shared ciphers: %s\n", buf);
2784 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
2786 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
2787 SSL_SESSION_print_keylog(bp, SSL_get_session(server_ssl));
2792 #ifdef EXIM_HAVE_SESSION_TICKET
2794 SSL_SESSION * ss = SSL_get_session(server_ssl);
2795 if (SSL_SESSION_has_ticket(ss)) /* 1.1.0 */
2796 debug_printf("The session has a ticket, life %lu seconds\n",
2797 SSL_SESSION_get_ticket_lifetime_hint(ss));
2802 /* Record the certificate we presented */
2804 X509 * crt = SSL_get_certificate(server_ssl);
2805 tls_in.ourcert = crt ? X509_dup(crt) : NULL;
2808 /* Only used by the server-side tls (tls_in), including tls_getc.
2809 Client-side (tls_out) reads (seem to?) go via
2810 smtp_read_response()/ip_recv().
2811 Hence no need to duplicate for _in and _out.
2813 if (!ssl_xfer_buffer) ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
2814 ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
2815 ssl_xfer_eof = ssl_xfer_error = FALSE;
2817 receive_getc = tls_getc;
2818 receive_getbuf = tls_getbuf;
2819 receive_get_cache = tls_get_cache;
2820 receive_ungetc = tls_ungetc;
2821 receive_feof = tls_feof;
2822 receive_ferror = tls_ferror;
2823 receive_smtp_buffered = tls_smtp_buffered;
2825 tls_in.active.sock = fileno(smtp_out);
2826 tls_in.active.tls_ctx = NULL; /* not using explicit ctx for server-side */
2834 tls_client_basic_ctx_init(SSL_CTX * ctx,
2835 host_item * host, smtp_transport_options_block * ob, tls_ext_ctx_cb * cbinfo,
2839 /* stick to the old behaviour for compatibility if tls_verify_certificates is
2840 set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
2841 the specified host patterns if one of them is defined */
2843 if ( ( !ob->tls_verify_hosts
2844 && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
2846 || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
2848 client_verify_optional = FALSE;
2849 else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
2850 client_verify_optional = TRUE;
2854 if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
2855 ob->tls_crl, host, client_verify_optional, verify_callback_client,
2859 if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
2861 cbinfo->verify_cert_hostnames =
2863 string_domain_utf8_to_alabel(host->name, NULL);
2867 DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
2868 cbinfo->verify_cert_hostnames);
2876 dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa, uschar ** errstr)
2879 const char * hostnames[2] = { CS host->name, NULL };
2882 if (DANESSL_init(ssl, NULL, hostnames) != 1)
2883 return tls_error(US"hostnames load", host, NULL, errstr);
2885 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
2886 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
2887 ) if (rr->type == T_TLSA && rr->size > 3)
2889 const uschar * p = rr->data;
2890 uint8_t usage, selector, mtype;
2891 const char * mdname;
2895 /* Only DANE-TA(2) and DANE-EE(3) are supported */
2896 if (usage != 2 && usage != 3) continue;
2903 default: continue; /* Only match-types 0, 1, 2 are supported */
2904 case 0: mdname = NULL; break;
2905 case 1: mdname = "sha256"; break;
2906 case 2: mdname = "sha512"; break;
2910 switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
2913 return tls_error(US"tlsa load", host, NULL, errstr);
2914 case 0: /* action not taken */
2918 tls_out.tlsa_usage |= 1<<usage;
2924 log_write(0, LOG_MAIN, "DANE error: No usable TLSA records");
2927 #endif /*SUPPORT_DANE*/
2931 #ifdef EXPERIMENTAL_TLS_RESUME
2932 /* On the client, get any stashed session for the given IP from hints db
2933 and apply it to the ssl-connection for attempted resumption. */
2936 tls_retrieve_session(tls_support * tlsp, SSL * ssl, const uschar * key)
2938 tlsp->resumption |= RESUME_SUPPORTED;
2939 if (tlsp->host_resumable)
2941 dbdata_tls_session * dt;
2943 open_db dbblock, * dbm_file;
2945 tlsp->resumption |= RESUME_CLIENT_REQUESTED;
2946 DEBUG(D_tls) debug_printf("checking for resumable session for %s\n", key);
2947 if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
2949 /* key for the db is the IP */
2950 if ((dt = dbfn_read_with_length(dbm_file, key, &len)))
2952 SSL_SESSION * ss = NULL;
2953 const uschar * sess_asn1 = dt->session;
2955 len -= sizeof(dbdata_tls_session);
2956 if (!(d2i_SSL_SESSION(&ss, &sess_asn1, (long)len)))
2960 ERR_error_string_n(ERR_get_error(),
2961 ssl_errstring, sizeof(ssl_errstring));
2962 debug_printf("decoding session: %s\n", ssl_errstring);
2965 #ifdef EXIM_HAVE_SESSION_TICKET
2966 else if ( SSL_SESSION_get_ticket_lifetime_hint(ss) + dt->time_stamp
2969 DEBUG(D_tls) debug_printf("session expired\n");
2970 dbfn_delete(dbm_file, key);
2973 else if (!SSL_set_session(ssl, ss))
2977 ERR_error_string_n(ERR_get_error(),
2978 ssl_errstring, sizeof(ssl_errstring));
2979 debug_printf("applying session to ssl: %s\n", ssl_errstring);
2984 DEBUG(D_tls) debug_printf("good session\n");
2985 tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
2986 tlsp->verify_override = dt->verify_override;
2987 tlsp->ocsp = dt->ocsp;
2991 DEBUG(D_tls) debug_printf("no session record\n");
2992 dbfn_close(dbm_file);
2998 /* On the client, save the session for later resumption */
3001 tls_save_session_cb(SSL * ssl, SSL_SESSION * ss)
3003 tls_ext_ctx_cb * cbinfo = SSL_get_ex_data(ssl, tls_exdata_idx);
3006 DEBUG(D_tls) debug_printf("tls_save_session_cb\n");
3008 if (!cbinfo || !(tlsp = cbinfo->tlsp)->host_resumable) return 0;
3010 # ifdef OPENSSL_HAVE_NUM_TICKETS
3011 if (SSL_SESSION_is_resumable(ss)) /* 1.1.1 */
3014 int len = i2d_SSL_SESSION(ss, NULL);
3015 int dlen = sizeof(dbdata_tls_session) + len;
3016 dbdata_tls_session * dt = store_get(dlen, TRUE);
3017 uschar * s = dt->session;
3018 open_db dbblock, * dbm_file;
3020 DEBUG(D_tls) debug_printf("session is resumable\n");
3021 tlsp->resumption |= RESUME_SERVER_TICKET; /* server gave us a ticket */
3023 dt->verify_override = tlsp->verify_override;
3024 dt->ocsp = tlsp->ocsp;
3025 (void) i2d_SSL_SESSION(ss, &s); /* s gets bumped to end */
3027 if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
3029 const uschar * key = cbinfo->host->address;
3030 dbfn_delete(dbm_file, key);
3031 dbfn_write(dbm_file, key, dt, dlen);
3032 dbfn_close(dbm_file);
3033 DEBUG(D_tls) debug_printf("wrote session (len %u) to db\n",
3042 tls_client_ctx_resume_prehandshake(
3043 exim_openssl_client_tls_ctx * exim_client_ctx, tls_support * tlsp,
3044 smtp_transport_options_block * ob, host_item * host)
3046 /* Should the client request a session resumption ticket? */
3047 if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
3049 tlsp->host_resumable = TRUE;
3051 SSL_CTX_set_session_cache_mode(exim_client_ctx->ctx,
3052 SSL_SESS_CACHE_CLIENT
3053 | SSL_SESS_CACHE_NO_INTERNAL | SSL_SESS_CACHE_NO_AUTO_CLEAR);
3054 SSL_CTX_sess_set_new_cb(exim_client_ctx->ctx, tls_save_session_cb);
3059 tls_client_ssl_resume_prehandshake(SSL * ssl, tls_support * tlsp,
3060 host_item * host, uschar ** errstr)
3062 if (tlsp->host_resumable)
3065 debug_printf("tls_resumption_hosts overrides openssl_options, enabling tickets\n");
3066 SSL_clear_options(ssl, SSL_OP_NO_TICKET);
3068 tls_exdata_idx = SSL_get_ex_new_index(0, 0, 0, 0, 0);
3069 if (!SSL_set_ex_data(ssl, tls_exdata_idx, client_static_cbinfo))
3071 tls_error(US"set ex_data", host, NULL, errstr);
3074 debug_printf("tls_exdata_idx %d cbinfo %p\n", tls_exdata_idx, client_static_cbinfo);
3077 tlsp->resumption = RESUME_SUPPORTED;
3078 /* Pick up a previous session, saved on an old ticket */
3079 tls_retrieve_session(tlsp, ssl, host->address);
3084 tls_client_resume_posthandshake(exim_openssl_client_tls_ctx * exim_client_ctx,
3087 if (SSL_session_reused(exim_client_ctx->ssl))
3089 DEBUG(D_tls) debug_printf("The session was reused\n");
3090 tlsp->resumption |= RESUME_USED;
3093 #endif /* EXPERIMENTAL_TLS_RESUME */
3096 /*************************************************
3097 * Start a TLS session in a client *
3098 *************************************************/
3100 /* Called from the smtp transport after STARTTLS has been accepted.
3103 cctx connection context
3104 conn_args connection details
3105 cookie datum for randomness; can be NULL
3106 tlsp record details of TLS channel configuration here; must be non-NULL
3107 errstr error string pointer
3109 Returns: TRUE for success with TLS session context set in connection context,
3114 tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
3115 void * cookie, tls_support * tlsp, uschar ** errstr)
3117 host_item * host = conn_args->host; /* for msgs and option-tests */
3118 transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
3119 smtp_transport_options_block * ob = tb
3120 ? (smtp_transport_options_block *)tb->options_block
3121 : &smtp_transport_option_defaults;
3122 exim_openssl_client_tls_ctx * exim_client_ctx;
3123 uschar * expciphers;
3125 static uschar peerdn[256];
3127 #ifndef DISABLE_OCSP
3128 BOOL request_ocsp = FALSE;
3129 BOOL require_ocsp = FALSE;
3133 store_pool = POOL_PERM;
3134 exim_client_ctx = store_get(sizeof(exim_openssl_client_tls_ctx), FALSE);
3135 exim_client_ctx->corked = NULL;
3139 tlsp->tlsa_usage = 0;
3142 #ifndef DISABLE_OCSP
3144 # ifdef SUPPORT_DANE
3145 if ( conn_args->dane
3146 && ob->hosts_request_ocsp[0] == '*'
3147 && ob->hosts_request_ocsp[1] == '\0'
3150 /* Unchanged from default. Use a safer one under DANE */
3151 request_ocsp = TRUE;
3152 ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
3153 " {= {4}{$tls_out_tlsa_usage}} } "
3159 verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK))
3160 request_ocsp = TRUE;
3162 # ifdef SUPPORT_DANE
3166 verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3170 rc = tls_init(&exim_client_ctx->ctx, host, NULL,
3171 ob->tls_certificate, ob->tls_privatekey,
3172 #ifndef DISABLE_OCSP
3173 (void *)(long)request_ocsp,
3175 cookie, &client_static_cbinfo, tlsp, errstr);
3176 if (rc != OK) return FALSE;
3178 tlsp->certificate_verified = FALSE;
3179 client_verify_callback_called = FALSE;
3183 if (conn_args->dane)
3185 /* We fall back to tls_require_ciphers if unset, empty or forced failure, but
3186 other failures should be treated as problems. */
3187 if (ob->dane_require_tls_ciphers &&
3188 !expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
3189 &expciphers, errstr))
3191 if (expciphers && *expciphers == '\0')
3196 !expand_check(ob->tls_require_ciphers, US"tls_require_ciphers",
3197 &expciphers, errstr))
3200 /* In OpenSSL, cipher components are separated by hyphens. In GnuTLS, they
3201 are separated by underscores. So that I can use either form in my tests, and
3202 also for general convenience, we turn underscores into hyphens here. */
3206 uschar *s = expciphers;
3207 while (*s) { if (*s == '_') *s = '-'; s++; }
3208 DEBUG(D_tls) debug_printf("required ciphers: %s\n", expciphers);
3209 if (!SSL_CTX_set_cipher_list(exim_client_ctx->ctx, CS expciphers))
3211 tls_error(US"SSL_CTX_set_cipher_list", host, NULL, errstr);
3217 if (conn_args->dane)
3219 SSL_CTX_set_verify(exim_client_ctx->ctx,
3220 SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
3221 verify_callback_client_dane);
3223 if (!DANESSL_library_init())
3225 tls_error(US"library init", host, NULL, errstr);
3228 if (DANESSL_CTX_init(exim_client_ctx->ctx) <= 0)
3230 tls_error(US"context init", host, NULL, errstr);
3238 if (tls_client_basic_ctx_init(exim_client_ctx->ctx, host, ob,
3239 client_static_cbinfo, errstr) != OK)
3242 #ifdef EXPERIMENTAL_TLS_RESUME
3243 tls_client_ctx_resume_prehandshake(exim_client_ctx, tlsp, ob, host);
3247 if (!(exim_client_ctx->ssl = SSL_new(exim_client_ctx->ctx)))
3249 tls_error(US"SSL_new", host, NULL, errstr);
3252 SSL_set_session_id_context(exim_client_ctx->ssl, sid_ctx, Ustrlen(sid_ctx));
3254 SSL_set_fd(exim_client_ctx->ssl, cctx->sock);
3255 SSL_set_connect_state(exim_client_ctx->ssl);
3259 if (!expand_check(ob->tls_sni, US"tls_sni", &tlsp->sni, errstr))
3263 DEBUG(D_tls) debug_printf("Setting TLS SNI forced to fail, not sending\n");
3265 else if (!Ustrlen(tlsp->sni))
3269 #ifdef EXIM_HAVE_OPENSSL_TLSEXT
3270 DEBUG(D_tls) debug_printf("Setting TLS SNI \"%s\"\n", tlsp->sni);
3271 SSL_set_tlsext_host_name(exim_client_ctx->ssl, tlsp->sni);
3273 log_write(0, LOG_MAIN, "SNI unusable with this OpenSSL library version; ignoring \"%s\"\n",
3280 if (conn_args->dane)
3281 if (dane_tlsa_load(exim_client_ctx->ssl, host, &conn_args->tlsa_dnsa, errstr) != OK)
3285 #ifndef DISABLE_OCSP
3286 /* Request certificate status at connection-time. If the server
3287 does OCSP stapling we will get the callback (set in tls_init()) */
3288 # ifdef SUPPORT_DANE
3292 if ( ((s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3293 || ((s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage"))
3295 { /* Re-eval now $tls_out_tlsa_usage is populated. If
3296 this means we avoid the OCSP request, we wasted the setup
3297 cost in tls_init(). */
3298 require_ocsp = verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
3299 request_ocsp = require_ocsp
3300 || verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
3307 SSL_set_tlsext_status_type(exim_client_ctx->ssl, TLSEXT_STATUSTYPE_ocsp);
3308 client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
3309 tlsp->ocsp = OCSP_NOT_RESP;
3313 #ifdef EXPERIMENTAL_TLS_RESUME
3314 if (!tls_client_ssl_resume_prehandshake(exim_client_ctx->ssl, tlsp, host,
3319 #ifndef DISABLE_EVENT
3320 client_static_cbinfo->event_action = tb ? tb->event_action : NULL;
3323 /* There doesn't seem to be a built-in timeout on connection. */
3325 DEBUG(D_tls) debug_printf("Calling SSL_connect\n");
3326 sigalrm_seen = FALSE;
3327 ALARM(ob->command_timeout);
3328 rc = SSL_connect(exim_client_ctx->ssl);
3332 if (conn_args->dane)
3333 DANESSL_cleanup(exim_client_ctx->ssl);
3338 tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL, errstr);
3344 debug_printf("SSL_connect succeeded\n");
3345 #ifdef EXIM_HAVE_OPENSSL_KEYLOG
3347 BIO * bp = BIO_new_fp(debug_file, BIO_NOCLOSE);
3348 SSL_SESSION_print_keylog(bp, SSL_get_session(exim_client_ctx->ssl));
3354 #ifdef EXPERIMENTAL_TLS_RESUME
3355 tls_client_resume_posthandshake(exim_client_ctx, tlsp);
3358 peer_cert(exim_client_ctx->ssl, tlsp, peerdn, sizeof(peerdn));
3360 tlsp->cipher = construct_cipher_name(exim_client_ctx->ssl, &tlsp->bits);
3361 tlsp->cipher_stdname = cipher_stdname_ssl(exim_client_ctx->ssl);
3363 /* Record the certificate we presented */
3365 X509 * crt = SSL_get_certificate(exim_client_ctx->ssl);
3366 tlsp->ourcert = crt ? X509_dup(crt) : NULL;
3369 tlsp->active.sock = cctx->sock;
3370 tlsp->active.tls_ctx = exim_client_ctx;
3371 cctx->tls_ctx = exim_client_ctx;
3380 tls_refill(unsigned lim)
3385 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", server_ssl,
3386 ssl_xfer_buffer, ssl_xfer_buffer_size);
3388 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
3389 inbytes = SSL_read(server_ssl, CS ssl_xfer_buffer,
3390 MIN(ssl_xfer_buffer_size, lim));
3391 error = SSL_get_error(server_ssl, inbytes);
3392 if (smtp_receive_timeout > 0) ALARM_CLR(0);
3394 if (had_command_timeout) /* set by signal handler */
3395 smtp_command_timeout_exit(); /* does not return */
3396 if (had_command_sigterm)
3397 smtp_command_sigterm_exit();
3398 if (had_data_timeout)
3399 smtp_data_timeout_exit();
3400 if (had_data_sigint)
3401 smtp_data_sigint_exit();
3403 /* SSL_ERROR_ZERO_RETURN appears to mean that the SSL session has been
3404 closed down, not that the socket itself has been closed down. Revert to
3405 non-SSL handling. */
3409 case SSL_ERROR_NONE:
3412 case SSL_ERROR_ZERO_RETURN:
3413 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3415 if (SSL_get_shutdown(server_ssl) == SSL_RECEIVED_SHUTDOWN)
3416 SSL_shutdown(server_ssl);
3418 tls_close(NULL, TLS_NO_SHUTDOWN);
3421 /* Handle genuine errors */
3423 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3424 log_write(0, LOG_MAIN, "TLS error (SSL_read): %s", ssl_errstring);
3425 ssl_xfer_error = TRUE;
3429 DEBUG(D_tls) debug_printf("Got SSL error %d\n", error);
3430 DEBUG(D_tls) if (error == SSL_ERROR_SYSCALL)
3431 debug_printf(" - syscall %s\n", strerror(errno));
3432 ssl_xfer_error = TRUE;
3436 #ifndef DISABLE_DKIM
3437 dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
3439 ssl_xfer_buffer_hwm = inbytes;
3440 ssl_xfer_buffer_lwm = 0;
3445 /*************************************************
3446 * TLS version of getc *
3447 *************************************************/
3449 /* This gets the next byte from the TLS input buffer. If the buffer is empty,
3450 it refills the buffer via the SSL reading function.
3452 Arguments: lim Maximum amount to read/buffer
3453 Returns: the next character or EOF
3455 Only used by the server-side TLS.
3459 tls_getc(unsigned lim)
3461 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3462 if (!tls_refill(lim))
3463 return ssl_xfer_error ? EOF : smtp_getc(lim);
3465 /* Something in the buffer; return next uschar */
3467 return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
3471 tls_getbuf(unsigned * len)
3476 if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
3477 if (!tls_refill(*len))
3479 if (!ssl_xfer_error) return smtp_getbuf(len);
3484 if ((size = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm) > *len)
3486 buf = &ssl_xfer_buffer[ssl_xfer_buffer_lwm];
3487 ssl_xfer_buffer_lwm += size;
3496 #ifndef DISABLE_DKIM
3497 int n = ssl_xfer_buffer_hwm - ssl_xfer_buffer_lwm;
3499 dkim_exim_verify_feed(ssl_xfer_buffer+ssl_xfer_buffer_lwm, n);
3505 tls_could_read(void)
3507 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm || SSL_pending(server_ssl) > 0;
3511 /*************************************************
3512 * Read bytes from TLS channel *
3513 *************************************************/
3517 ct_ctx client context pointer, or NULL for the one global server context
3521 Returns: the number of bytes read
3522 -1 after a failed read, including EOF
3524 Only used by the client-side TLS.
3528 tls_read(void * ct_ctx, uschar *buff, size_t len)
3530 SSL * ssl = ct_ctx ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3534 DEBUG(D_tls) debug_printf("Calling SSL_read(%p, %p, %u)\n", ssl,
3535 buff, (unsigned int)len);
3537 inbytes = SSL_read(ssl, CS buff, len);
3538 error = SSL_get_error(ssl, inbytes);
3540 if (error == SSL_ERROR_ZERO_RETURN)
3542 DEBUG(D_tls) debug_printf("Got SSL_ERROR_ZERO_RETURN\n");
3545 else if (error != SSL_ERROR_NONE)
3555 /*************************************************
3556 * Write bytes down TLS channel *
3557 *************************************************/
3561 ct_ctx client context pointer, or NULL for the one global server context
3564 more further data expected soon
3566 Returns: the number of bytes after a successful write,
3567 -1 after a failed write
3569 Used by both server-side and client-side TLS.
3573 tls_write(void * ct_ctx, const uschar *buff, size_t len, BOOL more)
3576 int outbytes, error;
3578 ? ((exim_openssl_client_tls_ctx *)ct_ctx)->ssl : server_ssl;
3579 static gstring * server_corked = NULL;
3580 gstring ** corkedp = ct_ctx
3581 ? &((exim_openssl_client_tls_ctx *)ct_ctx)->corked : &server_corked;
3582 gstring * corked = *corkedp;
3584 DEBUG(D_tls) debug_printf("%s(%p, %lu%s)\n", __FUNCTION__,
3585 buff, (unsigned long)len, more ? ", more" : "");
3587 /* Lacking a CORK or MSG_MORE facility (such as GnuTLS has) we copy data when
3588 "more" is notified. This hack is only ok if small amounts are involved AND only
3589 one stream does it, in one context (i.e. no store reset). Currently it is used
3590 for the responses to the received SMTP MAIL , RCPT, DATA sequence, only.
3591 We support callouts done by the server process by using a separate client
3592 context for the stashed information. */
3593 /* + if PIPE_COMMAND, banner & ehlo-resp for smmtp-on-connect. Suspect there's
3594 a store reset there, so use POOL_PERM. */
3595 /* + if CHUNKING, cmds EHLO,MAIL,RCPT(s),BDAT */
3597 if ((more || corked))
3599 #ifdef SUPPORT_PIPE_CONNECT
3600 int save_pool = store_pool;
3601 store_pool = POOL_PERM;
3604 corked = string_catn(corked, buff, len);
3606 #ifdef SUPPORT_PIPE_CONNECT
3607 store_pool = save_pool;
3615 buff = CUS corked->s;
3620 for (int left = len; left > 0;)
3622 DEBUG(D_tls) debug_printf("SSL_write(%p, %p, %d)\n", ssl, buff, left);
3623 outbytes = SSL_write(ssl, CS buff, left);
3624 error = SSL_get_error(ssl, outbytes);
3625 DEBUG(D_tls) debug_printf("outbytes=%d error=%d\n", outbytes, error);
3629 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3630 log_write(0, LOG_MAIN, "TLS error (SSL_write): %s", ssl_errstring);
3633 case SSL_ERROR_NONE:
3638 case SSL_ERROR_ZERO_RETURN:
3639 log_write(0, LOG_MAIN, "SSL channel closed on write");
3642 case SSL_ERROR_SYSCALL:
3643 log_write(0, LOG_MAIN, "SSL_write: (from %s) syscall: %s",
3644 sender_fullhost ? sender_fullhost : US"<unknown>",
3649 log_write(0, LOG_MAIN, "SSL_write error %d", error);
3658 /*************************************************
3659 * Close down a TLS session *
3660 *************************************************/
3662 /* This is also called from within a delivery subprocess forked from the
3663 daemon, to shut down the TLS library, without actually doing a shutdown (which
3664 would tamper with the SSL session in the parent process).
3667 ct_ctx client TLS context pointer, or NULL for the one global server context
3668 shutdown 1 if TLS close-alert is to be sent,
3669 2 if also response to be waited for
3673 Used by both server-side and client-side TLS.
3677 tls_close(void * ct_ctx, int shutdown)
3679 exim_openssl_client_tls_ctx * o_ctx = ct_ctx;
3680 SSL_CTX **ctxp = o_ctx ? &o_ctx->ctx : &server_ctx;
3681 SSL **sslp = o_ctx ? &o_ctx->ssl : &server_ssl;
3682 int *fdp = o_ctx ? &tls_out.active.sock : &tls_in.active.sock;
3684 if (*fdp < 0) return; /* TLS was not active */
3689 DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
3690 shutdown > 1 ? " (with response-wait)" : "");
3692 if ( (rc = SSL_shutdown(*sslp)) == 0 /* send "close notify" alert */
3696 rc = SSL_shutdown(*sslp); /* wait for response */
3700 if (rc < 0) DEBUG(D_tls)
3702 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3703 debug_printf("SSL_shutdown: %s\n", ssl_errstring);
3707 if (!o_ctx) /* server side */
3709 #ifndef DISABLE_OCSP
3710 sk_X509_pop_free(server_static_cbinfo->verify_stack, X509_free);
3711 server_static_cbinfo->verify_stack = NULL;
3714 receive_getc = smtp_getc;
3715 receive_getbuf = smtp_getbuf;
3716 receive_get_cache = smtp_get_cache;
3717 receive_ungetc = smtp_ungetc;
3718 receive_feof = smtp_feof;
3719 receive_ferror = smtp_ferror;
3720 receive_smtp_buffered = smtp_buffered;
3721 tls_in.active.tls_ctx = NULL;
3723 /* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
3726 SSL_CTX_free(*ctxp);
3736 /*************************************************
3737 * Let tls_require_ciphers be checked at startup *
3738 *************************************************/
3740 /* The tls_require_ciphers option, if set, must be something which the
3743 Returns: NULL on success, or error message
3747 tls_validate_require_cipher(void)
3750 uschar *s, *expciphers, *err;
3754 if (!(tls_require_ciphers && *tls_require_ciphers))
3757 if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
3759 return US"failed to expand tls_require_ciphers";
3761 if (!(expciphers && *expciphers))
3764 /* normalisation ripped from above */
3766 while (*s != 0) { if (*s == '_') *s = '-'; s++; }
3770 #ifdef EXIM_HAVE_OPENSSL_TLS_METHOD
3771 if (!(ctx = SSL_CTX_new(TLS_server_method())))
3773 if (!(ctx = SSL_CTX_new(SSLv23_server_method())))
3776 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3777 return string_sprintf("SSL_CTX_new() failed: %s", ssl_errstring);
3781 debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
3783 if (!SSL_CTX_set_cipher_list(ctx, CS expciphers))
3785 ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
3786 err = string_sprintf("SSL_CTX_set_cipher_list(%s) failed: %s",
3787 expciphers, ssl_errstring);
3798 /*************************************************
3799 * Report the library versions. *
3800 *************************************************/
3802 /* There have historically been some issues with binary compatibility in
3803 OpenSSL libraries; if Exim (like many other applications) is built against
3804 one version of OpenSSL but the run-time linker picks up another version,
3805 it can result in serious failures, including crashing with a SIGSEGV. So
3806 report the version found by the compiler and the run-time version.
3808 Note: some OS vendors backport security fixes without changing the version
3809 number/string, and the version date remains unchanged. The _build_ date
3810 will change, so we can more usefully assist with version diagnosis by also
3811 reporting the build date.
3813 Arguments: a FILE* to print the results to
3818 tls_version_report(FILE *f)
3820 fprintf(f, "Library version: OpenSSL: Compile: %s\n"
3823 OPENSSL_VERSION_TEXT,
3824 SSLeay_version(SSLEAY_VERSION),
3825 SSLeay_version(SSLEAY_BUILT_ON));
3826 /* third line is 38 characters for the %s and the line is 73 chars long;
3827 the OpenSSL output includes a "built on: " prefix already. */
3833 /*************************************************
3834 * Random number generation *
3835 *************************************************/
3837 /* Pseudo-random number generation. The result is not expected to be
3838 cryptographically strong but not so weak that someone will shoot themselves
3839 in the foot using it as a nonce in input in some email header scheme or
3840 whatever weirdness they'll twist this into. The result should handle fork()
3841 and avoid repeating sequences. OpenSSL handles that for us.
3845 Returns a random number in range [0, max-1]
3849 vaguely_random_number(int max)
3853 static pid_t pidlast = 0;
3855 uschar smallbuf[sizeof(r)];
3861 if (pidnow != pidlast)
3863 /* Although OpenSSL documents that "OpenSSL makes sure that the PRNG state
3864 is unique for each thread", this doesn't apparently apply across processes,
3865 so our own warning from vaguely_random_number_fallback() applies here too.
3866 Fix per PostgreSQL. */
3872 /* OpenSSL auto-seeds from /dev/random, etc, but this a double-check. */
3876 gettimeofday(&r.tv, NULL);
3879 RAND_seed(US (&r), sizeof(r));
3881 /* We're after pseudo-random, not random; if we still don't have enough data
3882 in the internal PRNG then our options are limited. We could sleep and hope
3883 for entropy to come along (prayer technique) but if the system is so depleted
3884 in the first place then something is likely to just keep taking it. Instead,
3885 we'll just take whatever little bit of pseudo-random we can still manage to
3888 needed_len = sizeof(r);
3889 /* Don't take 8 times more entropy than needed if int is 8 octets and we were
3890 asked for a number less than 10. */
3891 for (r = max, i = 0; r; ++i)
3897 #ifdef EXIM_HAVE_RAND_PSEUDO
3898 /* We do not care if crypto-strong */
3899 i = RAND_pseudo_bytes(smallbuf, needed_len);
3901 i = RAND_bytes(smallbuf, needed_len);
3907 debug_printf("OpenSSL RAND_pseudo_bytes() not supported by RAND method, using fallback.\n");
3908 return vaguely_random_number_fallback(max);
3912 for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
3915 /* We don't particularly care about weighted results; if someone wants
3916 smooth distribution and cares enough then they should submit a patch then. */
3923 /*************************************************
3924 * OpenSSL option parse *
3925 *************************************************/
3927 /* Parse one option for tls_openssl_options_parse below
3930 name one option name
3931 value place to store a value for it
3932 Returns success or failure in parsing
3938 tls_openssl_one_option_parse(uschar *name, long *value)
3941 int last = exim_openssl_options_size;
3942 while (last > first)
3944 int middle = (first + last)/2;
3945 int c = Ustrcmp(name, exim_openssl_options[middle].name);
3948 *value = exim_openssl_options[middle].value;
3962 /*************************************************
3963 * OpenSSL option parsing logic *
3964 *************************************************/
3966 /* OpenSSL has a number of compatibility options which an administrator might
3967 reasonably wish to set. Interpret a list similarly to decode_bits(), so that
3968 we look like log_selector.
3971 option_spec the administrator-supplied string of options
3972 results ptr to long storage for the options bitmap
3973 Returns success or failure
3977 tls_openssl_options_parse(uschar *option_spec, long *results)
3980 uschar * exp, * end;
3982 BOOL adding, item_parsed;
3984 /* Server: send no (<= TLS1.2) session tickets */
3985 result = SSL_OP_NO_TICKET;
3987 /* Prior to 4.80 we or'd in SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS; removed
3988 from default because it increases BEAST susceptibility. */
3989 #ifdef SSL_OP_NO_SSLv2
3990 result |= SSL_OP_NO_SSLv2;
3992 #ifdef SSL_OP_NO_SSLv3
3993 result |= SSL_OP_NO_SSLv3;
3995 #ifdef SSL_OP_SINGLE_DH_USE
3996 result |= SSL_OP_SINGLE_DH_USE;
3998 #ifdef SSL_OP_NO_RENEGOTIATION
3999 result |= SSL_OP_NO_RENEGOTIATION;
4008 if (!expand_check(option_spec, US"openssl_options", &exp, &end))
4011 for (uschar * s = exp; *s; /**/)
4013 while (isspace(*s)) ++s;
4016 if (*s != '+' && *s != '-')
4018 DEBUG(D_tls) debug_printf("malformed openssl option setting: "
4019 "+ or - expected but found \"%s\"\n", s);
4022 adding = *s++ == '+';
4023 for (end = s; (*end != '\0') && !isspace(*end); ++end) /**/ ;
4026 item_parsed = tls_openssl_one_option_parse(s, &item);
4030 DEBUG(D_tls) debug_printf("openssl option setting unrecognised: \"%s\"\n", s);
4033 DEBUG(D_tls) debug_printf("openssl option, %s %08lx: %08lx (%s)\n",
4034 adding ? "adding to " : "removing from", result, item, s);
4046 #endif /*!MACRO_PREDEF*/
4049 /* End of tls-openssl.c */